Updated on 2024/04/16

写真a

 
Ikeda Tomiki
 
Organization
Research and Development Initiative Institute Professor
External link

Degree

  • 工学博士 ( 京都大学 )

Education

  • 1978.3
     

    Kyoto University   doctor course   completed

Research History

  • 2011 -  

    Aoyama Gakuin University

  • 2011 -  

    Chuo University   Research and Development Initiative   Professor

  • 2009 -  

    Tokyo Institute of Technology   Chemical Resources Laboratory   Director in General

  • 1994 -  

    Tokyo Institute of Technology   Chemical Resources Laboratory

  • 1992 -  

    Tokyo Institute of Technology   Chemical Resources Laboratory

  • 1986 -  

    Tokyo Institute of Technology   Chemical Resources Laboratory

  • 1981 -  

    Tokyo Institute of Technology   Chemical Resources Laboratory

  • 1978 -  

    英国リバプール大学 博士研究員

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Professional Memberships

  •   - Now

    Royal Sciety of Chemistry, UK

  • アメリカ化学会

  • 電気化学会

  • 応用物理学会

  • 光化学協会

  • 日本液晶学会

  • 高分子学会

  • 日本化学会

  • The Americal Chemical Society

  • The Electrochemical Society of Japan

  • The Japan Society of Applied Physics

  • Japanese Photochemistry Association

  • Japanese Liquid Crystal Society

  • The Society of Polymer Science, Japan

  • Chemical Society of Japan

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Research Areas

  • Nanotechnology/Materials / Functional solid state chemistry  / 高分子化学

Papers

  • Can sunlight drive the photoinduced bending of polymer films?

    Ruoyuan Yin, Wanxian Xu, Mizuho Kondo, Chu-Chun Yen, Jun-ichi Mamiya, Tomiki Ikeda, Yanlei Yu

    JOURNAL OF MATERIALS CHEMISTRY   19 ( 20 )   3141 - 3143   2009

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

    Photoinduced bending and unbending behavior of crosslinked liquid-crystalline polymers containing azotolane moieties in side chains occurred upon irradiation with sunlight, according to the trans-cis photoisomerization of the azotolane moieties.

    DOI: 10.1039/b904973h

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  • Photomechanics: directed bending of a polymer film by light. Reviewed International journal

    Yanlei Yu, Makoto Nakano, Tomiki Ikeda

    Nature   425 ( 6954 )   145 - 145   2003.9

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    Language:English   Publisher:NATURE PUBLISHING GROUP  

    Polymer solutions and solids that contain light-sensitive molecules can undergo photo-contraction, whereby light energy is converted into mechanical energy. Here we show that a single film of a liquid-crystal network containing an azobenzene chromophore can be repeatedly and precisely bent along any chosen direction by using linearly polarized light. This striking photomechanical effect results from a photoselective volume contraction and may be useful in the development of high-speed actuators for microscale or nanoscale applications, for example in microrobots in medicine or optical microtweezers.

    DOI: 10.1038/425145a

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  • Inducing Motions of Polymers in Liquid Nitrogen with Light

    Toru Ube, Ikumi Suka, Shunya Ogikubo, Gaku Hashimoto, Masayuki Suda, Hiroshi M. Yamamoto, Tomiki Ikeda

    Advanced Materials   2023.10

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    Publishing type:Research paper (scientific journal)   Publisher:Wiley  

    Abstract

    Polymer materials that show macroscopic deformation in response to external stimuli are feasible for novel soft actuators including microactuators. Incorporation of photochromic moieties, such as azobenzenes, into polymer networks enables macroscopic deformation under irradiation with light through photoisomerization. Under cryogenic conditions, however, it has been difficult to induce macroscopic deformation as polymers lose their soft nature due to the severe restrictions of molecular motions. Here, activation of molecular motions and macroscopic deformation in liquid nitrogen only with light for polymers containing photochromic moieties is reported. Photoinduced bending of polymer networks with normal azobenzenes in liquid nitrogen is enabled by preliminary UV irradiation at room temperature to produce cis‐isomers. To realize photoinduced deformation directly in liquid nitrogen, polymer networks are functionalized with bridged azobenzenes, which exist as cis‐isomers in thermodynamic equilibrium. The films with bridged azobenzenes exhibit reversible photoisomerization and bending upon irradiation with light in liquid nitrogen without the need of preliminary irradiation, implying that the change in conformation of polymer chains can be isothermally induced even under cryogenic conditions. Achievement of flexible motions under cryogenic conditions through isothermal processes will greatly expand the operating temperature range of soft actuators.

    DOI: 10.1002/adma.202306402

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  • Shape programming and photoactuation of interpenetrating polymer networks containing azobenzene moieties Reviewed

    Toru Ube, Keigo Naito, Tomiki Ikeda

    JOURNAL OF MATERIALS CHEMISTRY C   11 ( 24 )   8100 - 8106   2023.6

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

    Crosslinked liquid-crystalline polymers (LCPs) with photochromic moieties exhibit macroscopic deformation upon irradiation with light. Controlling the 3D shapes of crosslinked LCPs leads to fabrication of photoactuators with desired structures and functions. Here, we investigate the shape memory effects and photoinduced deformation of interpenetrating polymer network (IPN) films composed of azobenzene LCP (PAzo) and poly(methyl methacrylate) (PMMA). PAzo/PMMA IPN films could be temporarily programmed into desired 3D structures with the aid of glass transition. The IPN films with temporary shapes showed high thermal stability compared to pristine PAzo films, which is ascribed to the gradual glass transition behaviour over a wide temperature range. The shape-programmed IPN samples showed various reversible deformation behaviours depending on the programmed shapes upon irradiation with UV and visible light. Furthermore, the thermal stability of temporary shapes allowed reversible photoactuation of shape-programmed samples at elevated temperatures as high as 100 degrees C. Formation of IPN films is a promising approach to enhance the design and functions of photoactuators consisting of crosslinked LCPs.

    DOI: 10.1039/d2tc04067k

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  • Photo/heat/electricity/pressure-driven photonic pattern with multimode memory effect Reviewed

    Yuanyuan Shang, Junchao Liu, Bo Guan, Jinbao Guo, Tomiki Ikeda, Jingxia Wang, Lei Jiang

    CHEMICAL ENGINEERING JOURNAL   457   2023.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCIENCE SA  

    The multimode memory effect of cholesteric liquid crystals (CLCs) photonic patterns has promising applications for the development of optical sensors, responsive colour decors, and camouflaging techniques. The present memory pattern is mainly aroused from the elastic effect of the polymer network or bistability of the CLC, it is desired for the development of alternative memory mode in non-polymerizable system, which may be helpful for the recyclable use of LC materials for the expired pattern. There remains a challenge for designing photonic patterns with multimode memory effects in a non-polymerized system owing to the limited availability of responsive materials. Herein, photo/heat/electricity/pressure multimode photonic memory pattern was firstly fabricated from non-polymerized cholesteric LC by mixing host LC E7, axially chiral azobenzene-based molecules (ACAMP), and S-form chiral dopants (S5011) based on the combination of PVA alignment layer and photoisomerization of ACAMP. The formed photonic patterns can be reversibly hidden/reappear by controlling the ambient temperature above/below the isotropic temperature or applying combined stimuli of electricity/pressure. The multi-memory pattern from the non-polymerizable system is friendly-environmental (recyclable use) with the simultaneous colour-change of the pattern and background under external stimulus. This study provides new insights into the development of multiresponsive nanostructures with tailorable functionalities, thus presenting new applications in diverse fields ranging from display technologies to information communication.

    DOI: 10.1016/j.cej.2022.141215

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  • Sunlight-driven smart windows with polymer/liquid crystal composites for autonomous control of optical properties Reviewed

    Toru Ube, Jumpei Imai, Marie Yoshida, Toru Fujisawa, Hiroshi Hasebe, Haruyoshi Takatsu, Tomiki Ikeda

    JOURNAL OF MATERIALS CHEMISTRY C   10 ( 35 )   12789 - 12794   2022.9

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

    We developed optically switchable smart windows driven by sunlight with polymer/liquid crystal (LC) composites containing azobenzene derivatives, which undergo trans-cis isomerization with high efficiency under sunlight. The composites exhibited high transparency in the initial state owing to homeotropic alignment of LCs, which was stabilized by polymer networks. Optical switching from the tranparent state to a light-scattering state was induced isothermally upon exposure to sunlight due to smectic A (SmA) to chiral nematic (N*) phase transition of LCs, triggered by trans-cis photoisomerization of the azobenzenes. The initial transparent state was restored in the absence of sunlight, resulting from N* to SmA phase transition induced by thermal cis-trans back isomerization of the azobenzenes. These autonomic smart windows utilizing only sunlight can be ubiquitously installed without additional artificial sources of energy.

    DOI: 10.1039/d2tc02754b

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  • High-Resolution Erasable "Live" Patterns Based on Controllable Ink Diffusion on the 3D Blue-Phase Liquid Crystal Networks Reviewed

    Fanshu Meng, Chenglin Zheng, Wenjie Yang, Bo Guan, Jingxia Wang, Tomiki Ikeda, Lei Jiang

    ADVANCED FUNCTIONAL MATERIALS   32 ( 15 )   2022.4

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    Colorful blue phase liquid crystal (BPLC) patterns have attracted wide research attention owing to their intriguing and advantageous properties and promising applications. However, it remains a challenge to develop novel and high-resolution patterns from BPLC owing to the complicated synthetic procedure for the functional molecules. This study reports a high-resolution "live" pattern by well-designed diffusion of 5CB ink on the wettability-modified BPLC networks. Interestingly, the shape and color of the as-prepared pattern change with time, which results in unique spectra change of the printed pattern, "first red-shift and subsequent blue-shift of the stopband position" and "continuous growth in reflectivity intensity" with time. The hydrophobic substrate greatly suppresses the random spreading and diffusion of ink, contributing to high-resolution patterns. The promising applications of live patterns for program display and active labels are demonstrated. Various high-resolution erasable colorful patterns are obtained. The structure reconfiguration of the writing and erasing processes is proved by transmitted electronic microscope images and Kossel diffraction diagrams, which ensures the reversible writing/erasing of the pattern on the membrane. This work is of significance for the development of novel rewritable paper and high-quality optic devices based on BPLC materials.

    DOI: 10.1002/adfm.202110985

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  • Single-, Dual-, Triple, and Quadruple-Wavelength Surface-Emitting Lasing in Blue-Phase Liquid Crystal Reviewed

    Jie Liu, Yujie Chen, Feng Jin, Jingxia Wang, Tomiki Ikeda, Lei Jiang

    ADVANCED MATERIALS   34 ( 9 )   2022.3

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    Soft organic lasers with multiwavelength output and high spectral purity are of crucial importance for versatile photonic devices, owing to their monochromaticity, coherence, and high intensity. However, there remain challenges for the achievement of surface-emitting multiwavelength lasing in soft photonic crystals, and the relative mechanisms need to be investigated. Herein, single-, dual-, triple-, and quadruple-wavelength lasers are successfully achieved in dye-doped blue-phase liquid crystal (BPLC) film. The number and wavelength of the lasing peaks can be manipulated by tuning the center of the bandgap, the order parameter of the laser dye, the quality of the resonance cavity, and even the pump energy. For single-wavelength lasing, a lasing peak with an ultranarrow linewidth of 0.04 nm (Q-factor of 13 454) is achieved. Multiwavelength lasing is attained based on the following aspects: i) the narrow bandgaps of the BPLCs with full width at half maximum of 14-20 nm; ii) a laser dye with high gain over a wide wavelength band, having a low-order parameter in the liquid crystal matrix; iii) appropriate relative positions between the reflection and fluorescence peaks; and iv) the highly ordered crystal lattice of BPLC film. The proposed single-to-quadruple-wavelength surface-emitting lasers can be employed as coherent light sources for next-generation optical devices.

    DOI: 10.1002/adma.202108330

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  • Janus Photochemical/Photothermal Azobenzene Inverse Opal Actuator with Shape Self-Recovery toward Sophisticated Motion Reviewed

    Junchao Liu, Yuanyuan Shang, Jie Liu, Jingxia Wang, Tomiki Ikeda, Lei Jiang

    ACS APPLIED MATERIALS & INTERFACES   14 ( 1 )   1727 - 1739   2022.1

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    Azobenzene actuators have aroused enormous research interest due to their excellent performance and promising applications in the fields of soft robots, artificial muscles, etc. However, there are still challenges for the fabrication of azobenzene actuators with a sophisticated actuation mode owing to the unitary actuation direction and slow thermal relaxation of cis-to trans-azobenzene mesogens. To solve these problems, this paper presents a facile fabrication method of a Janus azobenzene inverse opal actuator with one side made of the monodomain azobenzene polymer and the other side made of the polydomain azobenzene inverse opal structure. Gradient-layer spacing structure of the film in its cross section is proven by synchrotron small-angle X-ray diffraction. The introduction of the inverse opal structure mainly provides a polydomain mesogen alignment, large specific surface area, low elastic modulus, and structure color. The synergetic actuation of the photochemical/photothermal mode produces multiple actuation directions, a larger actuation force, and an alteration of the structure color. Shape self-recovery of this Janus azobenzene actuator contributes to some promising applications, such as crawling on a smooth surface, driving an engine axis, and logic electric circuit for the coding technique. This work is of great significance for the design and fabrication of novel-type photoactuators.

    DOI: 10.1021/acsami.1c19826

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  • Photoinduced Motions of Thermoplastic Polyurethanes Containing Azobenzene Moieties in Main Chains Reviewed

    Toru Ube, Romu Nakayama, Tomiki Ikeda

    MACROMOLECULES   55 ( 2 )   413 - 420   2022.1

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    Thermoplastic polyurethane containing azobenzene moieties in main chains was developed for photomobile materials capable of reversible photoactuation and shape programming, and was characterized for phase transition properties, microstructures, and photoinduced deformation behaviors. Photomobile films with glassy nature could be fabricated using both melt- and solution-processing methods, in contrast with conventional photomobile materials consisting of chemically cross-linked networks. The alignment of azobenzene moieties and macroscopic shapes in the initial states were controlled by external force under heating above glass transition temperature, which were stabilized by the formation of physical cross-links through hydrogen bonding interactions. The films with uniaxial alignment of azobenzene moieties showed reversible bending upon irradiation with UV and visible light, which could be repeated for 100 cycles. Physical cross-links in the present system can be an alternative for covalent cross-links in photomobile polymer materials, expanding the variety of designs with superior processability.

    DOI: 10.1021/acs.macromol.1c01827

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  • Liquid-Phase Super Photoactuator through the Synergetic Effects of a Janus Structure and Solvent/Thermal/Photo Responses Reviewed

    Junchao Liu, Jingxia Wang, Tomiki Ikeda, Lei Jiang

    ADVANCED FUNCTIONAL MATERIALS   31 ( 48 )   2021.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    Azobenzene actuator has attracted wide research attention in the fields of soft robots, artificial muscles, etc., owing to the typical photoresponsive material based on its reversible trans-cis isomerization. However, it remains challenging to enhance the actuation performance of azobenzene actuators through simple methods and can work in complex and variable environments. In contrast to complex molecular functional design, this study presents a Janus azobenzene inverse opal actuator: one side of a monodomain azobenzene polymer and the other side of a polydomain azobenzene inverse opal structure. The proposed design can significantly enhance the photoactuation performance in the liquid phase based on the synergetic effects of the Janus structure and the plastic influence of solvent/thermal/photo responses on the polymer segment. Promising applications of photo-driven ring rolling in the liquid phase are demonstrated. The results of this study are of great significance for the design and fabrication of novel-type azobenzene actuators in the liquid phase.

    DOI: 10.1002/adfm.202105728

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  • Diffusionless transformation of soft cubic superstructure from amorphous to simple cubic and body-centered cubic phases Reviewed

    Jie Liu, Wenzhe Liu, Bo Guan, Bo Wang, Lei Shi, Feng Jin, Zhigang Zheng, Jingxia Wang, Tomiki Ikeda, Lei Jiang

    NATURE COMMUNICATIONS   12 ( 1 )   2021.6

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:NATURE PORTFOLIO  

    In a narrow temperature window in going from the isotropic to highly chiral orders, cholesteric liquid crystals exhibit so-called blue phases, consisting of different morphologies of long, space-filling double twisted cylinders. Those of cubic spatial symmetry have attracted considerable attention in recent years as templates for soft photonic materials. The latter often requires the creation of monodomains of predefined orientation and size, but their engineering is complicated by a lack of comprehensive understanding of how blue phases nucleate and transform into each other at a submicrometer length scale. In this work, we accomplish this by intercepting nucleation processes at intermediate stages with fast cross-linking of a stabilizing polymer matrix. We reveal using transmission electron microscopy, synchrotron small-angle X-ray diffraction, and angle-resolved microspectroscopy that the grid of double-twisted cylinders undergoes highly coordinated, diffusionless transformations. In light of our findings, the implementation of several applications is discussed, such as temperature-switchable QR codes, micro-area lasing, and fabrication of blue phase liquid crystals with large domain sizes. The arrangements of defect lines in liquid crystal blue phases provide promising templates for photonic crystals. Here Liu et al. investigate in detail how inter-phase transitions proceed, by intercepting nucleation with on-demand cross linking of a supporting polymer matrix.

    DOI: 10.1038/s41467-021-23631-w

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  • Photoalignment in Polysiloxane Liquid-Crystalline Elastomers with Rearrangeable Networks Reviewed

    Toru Ube, Haruna Tsunoda, Kyohei Kawasaki, Tomiki Ikeda

    ADVANCED OPTICAL MATERIALS   9 ( 9 )   2021.5

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    Molecular alignment in liquid-crystalline elastomers with polysiloxane backbone is controlled with the aid of photoalignment and exchangeable links to enhance performance as photoactuators. The photoalignment is triggered by trans-cis-trans isomerization of azobenzene moieties, which are introduced at crosslinking points, upon irradiation with linearly polarized UV (LPUV) light under heating. The induced alignment is memorized by rearrangement of network structures through exchange reactions of covalent bonds. When irradiated with LPUV light, freestanding films show bending along with the alignment change in surface regions. Macroscopic shapes are also rememorized by exchange reactions at crosslinks. Combination of photoalignment and network rearrangement allows continuous deformation of freestanding films upon exposure to LPUV light with varying polarization directions. This approach enhances the degree of freedom in alignment control, photoactuation, and reshaping of polysiloxane-based liquid-crystalline elastomers, which are feasible as soft actuators.

    DOI: 10.1002/adom.202100053

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  • Inkless Rewritable Photonic Crystals Paper Enabled by a Light-Driven Azobenzene Mesogen Switch Reviewed

    Junchao Liu, Yao Wang, Jingxia Wang, Guofu Zhou, Tomiki Ikeda, Lei Jiang

    ACS APPLIED MATERIALS & INTERFACES   13 ( 10 )   12383 - 12392   2021.3

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    Rewritable paper, as an environment-friendly approach of information transmission, has potential possibility to conserve energy and promote a sustainable development of our society. Recently, photonic crystals (PCs) have become a research hotspot in the development of rewritable paper. However, there are still many shortcomings that limit the further application of PC paper, such as slow response sensitivity, short-cycle lifetime, poor storage stability, and so on. Herein, we constructed an optically rewritable azobenzene inverse opals (AZOIOs) with a thin film (ca. 1 mu m) plated on an inverse opal structure based on the UV/vis switchable structure color of the sample. The top thin film acts as a protective layer to avoid the large deformation of the pore structure and the bottom inverse opal structure with refractive index/pore structure change that provides reversible structure color. Large, reversible, and rapid bandgap shift (ca. 60 nm, 2 s) of AZOIOs can be repeated more than 100 times under alternating UV/vis irradiation based on isomerization of high content of the azobenzene group. On-demand long-time preservation pattern can be obtained by the appearance of azobenzene's intrinsic color. The proof of concept for rewritable PC paper is demonstrated herein. Such inkless rewritable colorful paper paves a way for developing novel display technology.

    DOI: 10.1021/acsami.0c22668

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  • Photonic Shape Memory Polymer Based on Liquid Crystalline Blue Phase Films Reviewed

    Jiajia Yang, Weidong Zhao, Zhou Yang, Wanli He, Jingxia Wang, Tomiki Ikeda, Lei Jiang

    ACS APPLIED MATERIALS & INTERFACES   11 ( 49 )   46124 - 46131   2019.12

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    Photonic shape memory (SM) polymers based on liquid crystalline blue phase (BP) films have been fabricated by self-assembly and subsequent photo polymerization of liquid-crystal mixtures. These freestanding BP films exhibit narrow photonic band gaps and high reflectivity in the visible wavelength range. Multiple blue-shift colors are achieved by SM programming process at different mechanical pressures. The blue-shift colors can be attributed to a decrease of effective BP pitch along the viewing direction caused by the compressed deformation of the BP films, which are confirmed by a three-dimensional interometric profile. The deformed BP films can recover to their original shapes and reflecting colors by heating the polymer films to temperatures above the glass-transition temperature. Quantitative relationships between the shape change and optical response are established for understanding this SM effect. What is more, the temporary photonic patterns can be reversibly written and erased for dozens of cycles without apparent degradation, making these freestanding BP films appealing as rewritable photonic papers and optical sensors.

    DOI: 10.1021/acsami.9b14202

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  • Printable photonic polymer coating based on a monodomain blue phase liquid crystal network Reviewed

    Jiajia Yang, Weidong Zhao, Zhou Yang, Wanli He, Jingxia Wang, Tomiki Ikeda, Lei Jiang

    JOURNAL OF MATERIALS CHEMISTRY C   7 ( 44 )   13764 - 13769   2019.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

    Fabrication of liquid-crystalline polymer networks with periodic nanoscale features is highly desired for photonic applications. Here, a printable photonic polymer coating has been fabricated from a monodomain liquid crystalline blue phase (BP) network. The BP polymer coating with high reflectivity is covalently linked to the glass substrate, which can be patterned by using an LC-ink to swell the network. The degree of swelling depends on the printed amount of LC-ink which can be controlled through adjusting the voltages of the inkjet printer. Arbitrary multicolour patterns covering the visible spectrum from 451 to 618 nm can be printed and erased multiple times, making these BP polymer coatings promising as rewritable photonic papers and responsive photonic materials.

    DOI: 10.1039/c9tc05052c

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  • Photomobile Polymer Materials with Complex 3D Deformation, Continuous Motions, Self-Regulation, and Enhanced Processability Reviewed

    Toru Ube, Tomiki Ikeda

    ADVANCED OPTICAL MATERIALS   7 ( 16 )   2019.8

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    Language:English   Publisher:WILEY-V C H VERLAG GMBH  

    Liquid-crystalline polymers with photodeformable properties have been extensively studied due to their ability of wireless conversion of light energy into mechanical work. With the development of crosslinked liquid-crystalline polymers, various 3D motions, such as bending, twisting, oscillation, rotation, and translational motion have been successfully induced. Recent trends for developing soft robots and microrobots accelerate the progress of photomobile polymer materials. This review is focused on recent advances in the field of photomobile materials based on liquid-crystalline polymers. The structure-function relationship in photomobile polymer materials is overviewed, and the progress in recent years is detailed in terms of complex 3D deformation, continuous motions, self-regulation, and processability.

    DOI: 10.1002/adom.201900380

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  • Fabrication and photonic applications of large-domain blue phase films Reviewed

    Jiajia Yang, Jie Liu, Bo Guan, Wanli He, Zhou Yang, Jingxia Wang, Tomiki Ikeda, Lei Jiang

    JOURNAL OF MATERIALS CHEMISTRY C   7 ( 31 )   9460 - 9466   2019.8

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

    Here, a facile method is put forward to fabricate freestanding, large-domain blue phase (BP) films based on self-assembly technology. This fabrication method enables the formation of BP domains with large-scale lateral dimensions of similar to 230 mu m, which exhibit sharp photonic bandgaps with high reflectivity. In addition, the large-domain BP structures with good optical performances can be preserved after photopolymerization. What is more, the long-range periodic nanostructures of double-twist cylinders can be directly visualized through transmission electron microscopy, providing a powerful tool to investigate BP structures at the nanoscale. Furthermore, dual-wavelength lasing is achieved by doping the large-domain BP films with fluorescent dyes, which is firstly observed in BP materials.

    DOI: 10.1039/c9tc02938a

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  • Bio-inspired liquid crystal actuator materials Reviewed

    Yuanyuan Shang, Jingxia Wang, Tomiki Ikeda, Lei Jiang

    JOURNAL OF MATERIALS CHEMISTRY C   7 ( 12 )   3413 - 3428   2019.3

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    Language:English   Publisher:ROYAL SOC CHEMISTRY  

    Liquid crystal elastomers, serving as a new kind of intelligent material, have demonstrated important application in the fields of microactuators, artificial muscles, microfluid transportation and intelligent sensors by virtue of their characteristics of spontaneous reversible deformation under external field stimulation. In this paper, we have reviewed the recent research progress of liquid crystal actuator materials, including of phototropic, thermotropic, photothermal and solvent/humidity-based liquid crystal actuators. The processing techniques, deformation response and actuation mechanism of liquid crystal elastomers were discussed and the relative application prospects were put forward. This work will provide important insights for the construction and development of novel liquid crystal optical devices.

    DOI: 10.1039/c9tc00107g

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  • A UV-Responsive Multifunctional Photoelectric Device Based on Discotic Columnar Nanostructures and Molecular Motors Reviewed

    Cheng Zou, Jian Sun, Meng Wang, Jingxia Wang, Yuchen Wu, Lanying Zhang, Zhongpeng Zhu, Guirong Xiong, Lei Jiang, Tomiki Ikeda, Huai Yang

    ADVANCED MATERIALS   31 ( 8 )   2019.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    Orientation control of ordered materials would not only produce new physical phenomenon but also facilitate the development of fancy devices. Discotic liquid crystals (DLCs) form 1D charge transport pathway by self-organizing into columnar nanostructures via pi-pi stacking. However, controlling the electrical properties in such nanostructures with some direct and instant way is a formidable task for their high viscosity and insensitivity to external stimuli. Herein, the arbitrary control over electrical conductivity of such columnar nanostructures is achieved with UV light by incorporating DLCs with molecular motors. Highly ordered DLC microstripe arrays are generated on desired substrate through a capillary bridge dewetting strategy. The conductivity of the microstripes could be continuously modulated by 365 nm light due to the influence of molecular motion under UV irradiation on the electron orbital overlap of columnar nanostructures. This is so because the disorder degree of the DLC molecules is associated with the intensity of UV light and the doping concentration of molecular motors. Moreover, the device shows memory effect and reversible conductivity change. The DLC microstripe arrays are very promising for the applications in UV detectors, memory devices, optical switches, and so on.

    DOI: 10.1002/adma.201806016

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  • Patterning Smectic Liquid Crystals for OFETs at Low Temperature Reviewed

    Cheng Zou, Naoto Yanahashi, Yuchen Wu, Jingxia Wang, Cuihong Zhang, Guirong Xiong, Huai Yang, Lei Jiang, Tomiki Ikeda

    ADVANCED FUNCTIONAL MATERIALS   29 ( 7 )   2019.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    The preparation of regular microstructures with liquid crystalline materials for organic field effect transistors (OFETs) is an attractive but challenging issue. However, it is usually limited by the difficulty of forming large-area single crystals aligned in a desirable direction. Herein, several terthiophene (TTP) smectic liquid crystals such as 8-TTP-8 and 12-TTP-11OH are patterned into highly crystalline microstripes by a sandwich system through a dewetting method. Morphology and orientation of the microstripes strongly depend on preparation temperature. Microstripes prepared below crystalline temperature are uniform, well-ordered, and show high field effect transistor (FET) mobility. Meanwhile, pi-pi stacking direction of the TTP backbone is perpendicular to the microstripe and the molecules stack in layer structure, standing up on the SiO2/Si substrate, which would provide an effective pathway for p-type charge transport. However, higher preparation temperatures at liquid crystalline or isotropic liquid range induce many defects in the crystal formation process and cause incline of the unit cell, thus leading to a sharp decrease in FET mobility. A possible mechanism of molecular stacking at different temperature range is proposed. This strategy promised to provide a new opportunity for the high cost-efficiency fabrication of OFETs.

    DOI: 10.1002/adfm.201804838

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  • Fabrication of photomobile polymer materials with phase-separated structure of crosslinked azobenzene liquid-crystalline polymer and poly(dimethylsiloxane) Reviewed

    Toru Ube, Takuya Yoda, Tomiki Ikeda

    LIQUID CRYSTALS   45 ( 13-15 )   2269 - 2273   2018.12

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    Composite systems of liquid crystals (LCs) and polymers have been extensively studied in various forms such as polymer-dispersed LCs and polymer-stabilised LCs. Blending LCs and polymers is an effective approach to design functional materials with stimuli responsiveness and durability. Here, we show the development of a novel composite material with crosslinked azobenzene LC polymer (PAzo) and poly (dimethylsiloxane) (PDMS) aiming at the improvement of photomobile polymer materials in mechanical properties. The composite films were prepared by photopolymerisation of azobenzene monomers in PDMS elastomers. By forming phase separated structure, in which PAzo chains were dispersed in PDMS matrix, fracture strain of photomobile polymer materials was significantly enhanced. The composite film showed macroscopic bending upon irradiation with UV light. This result implies that PAzo domains in polymer matrix can work as microactuators to afford macroscopic deformation of the whole film. The further improvement of this system in photomechanical properties would be feasible through adequate control of composition and the alignment of mesogens.[GRAPHICS].

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  • A Hydrophilic/Hydrophobic Janus Inverse-Opal Actuator via Gradient Infiltration Reviewed

    Dajie Zhang, Jie Liu, Bo Chen, Yong Zhao, Jingxia Wang, Tomiki Ikeda, Lei Jiang

    ACS NANO   12 ( 12 )   12149 - 12158   2018.12

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    Janus/gradient actuating materials have become promising candidates for actuating devices. The fabrication of functional Janus gradient actuators remains a challenge. This paper presents a facile fabrication of a hydrophilic/hydrophobic Janus inverse opal actuator via gradient infiltration. The Janus characteristics of the fabricated actuator were attributed to gradient infiltration along the thickness of the film caused by the gradient light intensity and the distinct polymerization behavior of ionic liquids and methyl methacrylate in the methanol system. The Janus film demonstrated directional bending upon water vapor adsorption, with a bending angle approaching 1440 in 4 s, accompanied by structure color/optic signal alteration. The actuating behaviors were effectively modulated by changing the composition of the film and the solvent system. Promising applications of this Janus solvent actuator were demonstrated in two sets of tests: driving an engine and lifting cargo. This work provides insight into the design and fabrication of multifunctional humidity-actuating materials.

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  • Photoinduced deformation and isomerization of azobenzene liquid-crystalline polymer films at cryogenic temperature Reviewed

    Shunya Ogikubo, Gaku Hashimoto, Toru Ube, Masayuki Suda, Hiroshi Yamamoto, Tomiki Ikeda

    Molecular Crystals and Liquid Crystals   676 ( 1 )   30 - 35   2018.11

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    We prepared 2 types of crosslinked liquid-crystalline polymers (CLCPs) (polyacrylates) with the same side-chain length but a different position of an azobenzene moiety in the side chain. We evaluated photoinduced deformation behavior of the CLCP films and photoisomerization behavior of azobenzene in the films at cryogenic temperature. Azobenzene moieties in both CLCP films showed no trans-cis isomerization and neither film exhibited bending behavior upon irradiation with UV light in liquid nitrogen [77 K]. On the other hand, when the film included azobenzene with a long spacer and a short tail, cis-trans isomerization of azobenzene and photoinduced deformation were observed in liquid nitrogen.

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  • Supramolecular assemblies composed of polymer brushes and conjugated molecules for organic photovoltaics Reviewed

    Romu Nakayama, Toru Ube, Kenji Katayama, Masa-aki Haga, Tomiki Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   676 ( 1 )   24 - 29   2018.11

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    Poly(4-vinylpyridine) (P4VP) brushes were grafted onto a substrate via Cu(0)-mediated atom transfer radical polymerization and 1-pyrenebutyric acid (PBA) was incorporated into the brushes through hydrogen bonding interactions with P4VP by immersing the resulting substrate in PBA solution. Fluorescence measurements performed on the substrate after immersion showed that PBA units formed excimers even after the substrate was rinsed with dichloromethane, which confirms the formation of hydrogen bonds between pyridyl groups in the P4VP brushes and carboxyl groups of PBAs.

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  • Remolding of Photoresponsive Polymer Materials by Means of Dynamic Covalent Bonds In a Main Chain Reviewed

    Masaya Matsushita, Kyohei Kawasaki, Toru Ube, Tomiki Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   676 ( 1 )   17 - 23   2018.11

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    We prepared crosslinked azobenzene main-chain liquid-crystalline polymers (MCLCPs), in which the exchange of crosslinks can be brought about by transesterification reactions. The exchangeable crosslinks enable reshaping and self-healing of the MCLCPs upon heating. Furthermore, the stress generated by stretching the MCLCP film is completely relaxed at 180 degrees C through rearrangement of networks. The film after hot-drawing shows reversible bending behavior upon irradiation with UV and visible light.

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  • Reversible solvent- sensitive actuator with continuous bending/ debending process from liquid crystal elastomer- colloidal material Reviewed

    Yuanyuan Shang, Junchao Liu, Manbo Zhang, Wanli He, Xinyu Cao, Jingxia Wang, Tomiki Ikeda, Lei Jiang

    SOFT MATTER   14 ( 27 )   5547 - 5553   2018.7

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    A reversible solvent-sensitive actuator with a continuous bending/debending process is fabricated by over-infiltration of liquid crystal monomers into a colloidal template and subsequent photopolymerization. The fabricated actuator exhibits a maximum bending angle of 1080 degrees in 1.58 s in dichloromethane, accompanied with successive debending in 0.32 s. The behavior of the actuator can be modulated by changing the solvent type, film thickness/length and molar ratio of A6OCB/C6M. This study will provide an important experimental and theoretical basis for the development of novel actuators.

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  • Patterning of Discotic Liquid Crystals with Tunable Molecular Orientation for Electronic Applications Reviewed

    Cheng Zou, Jingxia Wang, Meng Wang, Yuchen Wu, Kehua Gu, Zhihao Shen, Guirong Xiong, Huai Yang, Lei Jiang, Tomiki Ikeda

    SMALL   14 ( 21 )   2018.5

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    The large-area formation of functional micropatterns with liquid crystals is of great significance for diversified applications in interdisciplinary fields. Meanwhile, the control of molecular alignment in the patterns is fundamental and prerequisite for the adequate exploitation of their photoelectric properties. However, it would be extremely complicated and challenging for discotic liquid crystals (DLCs) to achieve the goal, because they are insensitive to external fields and surface chemistry. Herein, a simple method of patterning and aligning DLCs on flat substrates is disclosed through precise control of the formation and dewetting of the capillary liquid bridges, within which the DLC molecules are confined. Large-area uniform alignment occurs spontaneously due to directional shearing force when the solvent is slowly evaporated and programmable patterns could be directly generated on desired substrates. Moreover, the in-plane column direction of DLCs is tunable by slightly tailoring their chemical structures which changes their self-assembly behaviors in liquid bridges. The patterned DLCs show molecular orientation-dependent charge transport properties and are promising for templating self-assembly of other materials. The study provides a facile method for manipulation of the macroscopic patterns and microscopic molecular orientation which opens up new opportunities for electronic applications of DLCs.

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  • Multi-functional organosilane-polymerized carbon dot inverse opals Reviewed

    Junchao Liu, Junkai Ren, Zheng Xie, Bo Guan, Jingxia Wang, Tomiki Ikeda, Lei Jiang

    NANOSCALE   10 ( 10 )   4642 - 4649   2018.3

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    This paper demonstrates multi-functional optical properties of organosilane-polymerized carbon dot inverse opals, such as tricolor-fluorescence, fluorescence enhancement, multi-color micro-patterns for anti-fake applications and a thermally-induced blueshift of bandgaps. It is of significance for the design and fabrication of novel optical devices.

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  • Liquid-crystalline elastomer photoactuator with photorearrangeable network structures Reviewed

    Haruna Tsunoda, Kyohei Kawasaki, Toru Ube, Tomiki Ikeda

    Molecular Crystals and Liquid Crystals   662 ( 1 )   61 - 67   2018.2

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    Crosslinked liquid-crystalline polymers (CLCPs) containing azobenzene moieties show reversible macroscopic deformation upon irradiation with light. The deformation of CLCPs strongly depends on alignment of mesogens. Therefore, it is desirable that the alignment of mesogens in CLCPs can be freely controlled even after crosslinking. We successfully realigned the mesogens in CLCPs with the aid of dynamic covalent bonds to accomplish this challenge. In this study, we prepared CLCP films containing dynamic covalent bonds and photoalignable azobenzene moieties. Photoalignment of the films was performed by irradiation with linearly polarized UV light at 120°C. The films after photoalignment showed bending behavior along the direction in which the mesogens had been realigned by photoalignment when irradiated with unpolarized UV light. This result indicates that alignment of mesogens in the films changes before and after photoalignment even after crosslinking.

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  • Formation of ordered nanostructures in liquid-crystalline block copolymers with side-chain semiconductor materials Reviewed

    Naoto Yanahashi, Toru Ube, Tomiki Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   662 ( 1 )   68 - 74   2018

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    We developed a novel block copolymer composed of poly(ethylene oxide) (PEO) and polymethacrylate functionalized with liquid-cryst-alline oligothiophene by using the atom transfer radical polymerization (ATRP), aiming at application to organic photovoltaic (OPV) cells. Thermal investigation showed that the resultant polymer exhibits liquid-crystalline phases both on heating and cooling. Morphologies of the thin films of the block copolymer were investigated by atomic force microscopy (AFM). Microphase separation with a small size of almost 10nm (nano-phase-separated structures) was observed upon annealing.

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  • Electrowetting-Induced Morphological Evolution of Metal-Organic Inverse Opals toward a Water-Lithography Approach Reviewed

    Junchao Liu, Lun Wan, Manbo Zhang, Kejian Jiang, Kai Song, Jingxia Wang, Tomiki Ikeda, Lei Jiang

    ADVANCED FUNCTIONAL MATERIALS   27 ( 7 )   2017.2

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    This paper presents a unique morphological evolution of metal-organic inverse opals (Pb(NO3)(2)-poly(St-MMA-AA)) subjected to an electrowetting process. The morphology of the building blocks changes from interconnected pores to separated hollow spheres during the electrowetting process, accompanied by an unusual blue-shift of the stopband position and the decreased wettability of the film. This morphology evolution is attributed to the simultaneous collapse/reconstruction of the metal-organic frame owing to the partial dissolution of the metal salt and the interfacial assembly of the metal-organic coordination around the skeleton. The adjustable morphology can be developed as a novel and simple water-lithography approach for the creation of the photonic crystal pattern.

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  • Interpenetrating polymer networks of liquid-crystalline azobenzene polymers and poly(dimethylsiloxane) as photomobile materials Reviewed

    T. Ube, K. Minagawa, T. Ikeda

    Soft Matter   13 ( 35 )   5820 - 5823   2017

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    We developed photomobile polymer materials with interpenetrating polymer network (IPN) structures composed of crosslinked liquid-crystalline azobenzene polymer (PAzo) and poly(dimethylsiloxane) (PDMS). By introducing PDMS into a PAzo template network, IPN was formed without disturbing the alignment of mesogens in the PAzo network. The films showed macroscopic bending behavior upon irradiation with UV and visible light. Although the IPN film showed a phase separated structure, the bending speed was significantly enhanced compared with the pristine film of PAzo, thanks to the soft nature of PDMS. The present method of preparing IPNs can be a promising approach to combine PAzo with various polymers and enhance the mechanical and photoresponsive properties.

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  • Photomobile Liquid-Crystalline Elastomers with Rearrangeable Networks Reviewed

    Toru Ube, Kyohei Kawasaki, Tomiki Ikeda

    ADVANCED MATERIALS   28 ( 37 )   8212 - 8217   2016.10

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    Incorporation of dynamic covalent bonds into photomobile liquid-crystalline elastomers with a polysiloxane backbone enables the alignment of mesogens and macroscopic shapes to be controlled through the rearrangement of the network topology, even after the formation of chemically crosslinked networks. The reshaped samples show various sophisticated 3D motions upon irradiation with UV and visible light, depending on their initial shapes.

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  • Nano Structures of Thin Films of Block Copolymers with Oligothiophene Side Chains Reviewed

    Masahiro Kaneko, Nana Takayanagi, Toru Ube, Masa-Aki Haga, Tomiki Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   617 ( 1 )   58 - 66   2015.8

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  • Synthesis of Polythiophene with a Photo-Crosslinkable Side Chain Reviewed

    Takahito Kosaka, Toru Ube, Masa-Aki Haga, Tomiki Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   617 ( 1 )   67 - 72   2015.8

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  • Remoldable Crosslinked Liquid-Crystalline Polysiloxane with Side Chain Mesogens Based on Exchangeable Crosslinks Reviewed

    Kyohei Kawasaki, Toru Ube, Tomiki Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   614 ( 1 )   62 - 66   2015.6

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    Crosslinked liquid-crystalline polymers (CLCPs) show unique behavior of deforming macroscopically when stimulated with heat, electricity and light. However, they cannot be remolded and reshaped once prepared. Here, we designed crosslinked polysiloxane with side chain mesogens that contain exchangeable crosslinking points based on transesterification between phenyl benzoates and hydroxy groups. After the formation of a polymer network, a base catalyst was introduced into the CLCP. When heated at 80 degrees C, a piece of the CLCP was reshaped into a film and separate pieces of the CLCP were fused together, indicating that the CLCP is remoldable.

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  • Photomobile Polymer Materials: Photoresponsive Behavior of Cross-Linked Liquid-Crystalline Polymers with Mesomorphic Diarylethenes Reviewed

    Jun-ichi Mamiya, Akito Kuriyama, Naoki Yokota, Munenori Yamada, Tomiki Ikeda

    CHEMISTRY-A EUROPEAN JOURNAL   21 ( 8 )   3174 - 3177   2015.2

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    Cross-linked liquid-crystalline (LC) polymers with a mesomorphic diarylethene were prepared to demonstrate a versatile strategy for cross-linked photochromic LC polymers as photomobile materials. Upon exposure to UV light to cause photocyclization of the diarylethene chromophore, the cross-linked polymer films bend toward an actinic light source. By irradiation with visible light to cause a closed-ring to open-ring isomerization, the bent films revert to the initial flat state. Without visible-light irradiation, the bent films remain bent even at 120 degrees C, indicating high thermal stability of the cross-linked diarylethene LC polymers.

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  • Structural dynamics in azobenzene liquid crystal polymer films studied by microscopic time-resolved technique Reviewed

    Kenji Katayama, Shota Kuwahara, Tomiki Ikeda

    LIQUID CRYSTALS XIX   9565   2015

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    We studied the photo-induced dynamics in a LC polymer film including azobenzene by using a time-resolved and a microscopic technique. The film was confined in a liquid crystal cell, while it is a photomobile film under a free standing condition, which is triggered by the photoisomerization of azobenezene. From the result of the time-resolved measurements, the change inside the film induced by UV irradiation was highly anisotropic polarization change. Microscopic observation revealed that the film was consisted of ordered and disordered region with a patched structure, and the UV induced change was travelled in the ordered region on the order of seconds.

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  • Photomobile Polymer Materials with Crosslinked Liquid-Crystalline Structures: Molecular Design, Fabrication, and Functions Reviewed

    Toru Ube, Tomiki Ikeda

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   53 ( 39 )   10290 - 10299   2014.9

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    Crosslinked liquid-crystalline polymer materials that macroscopically deform when irradiated with light have been extensively studied in the past decade because of their potential in various applications, such as microactuators and microfluidic devices. The basic motions of these materials are contraction-expansion and bending-unbending, which are observed mainly in polysiloxanes and polyacrylates that contain photochromic moieties. Other sophisticated motions such as twisting, oscillation, rotation, and translational motion have also been achieved. In recent years, efforts have been made to improve the photoresponsive and mechanical properties of this novel class of materials through the modification of molecular structures, development of new fabrication methods, and construction of composite structures. Herein, we review structures, functions, and working mechanisms of photomobile materials and recent advances in this field.

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  • Photomobile Polymer Materials with Double Network Structures: Crosslinked Azobenzene Liquid-Crystalline Polymer/Methacrylate Composites Reviewed

    Kiyohide Takado, Toru Ube, Tomiki Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   601 ( 1 )   43 - 48   2014.9

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    We prepared photomobile polymer materials composed of crosslinked azobenzene liquid-crystalline polymers (LCPs) and methacrylates with interpenetrating polymer network (IPN) structures, and explored their photoresponsive behavior. The IPN films exhibited reversible bending upon photoirradiation. In addition, the durability of the IPN films was much higher than that of the pristine crosslinked azobenzene LCP films.

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  • Photoinduced Bending Behavior of Cross-linked Azobenzene Liquid-Crystalline Polymer Films with a Poly(oxyethylene) Backbone Reviewed

    Jiu-an Lv, Weiru Wang, Jixiang Xu, Tomiki Ikeda, Yanlei Yu

    MACROMOLECULAR RAPID COMMUNICATIONS   35 ( 14 )   1266 - 1272   2014.7

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    Cross-linked azobenzene liquid-crystalline polymer films with a poly(oxyethylene) backbone are synthesized by photoinitiated cationic copolymerization. Azobenzene moieties in the film surface toward the light source are simultaneously photoaligned during photopolymerization with unpolarized 436 nm light and thus form a splayed alignment in the whole film. The prepared films show reversible photoinduced bending behavior with opposite bending directions when different surfaces of one film face to ultraviolet light irradiation.

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  • Facile strain analysis of largely bending films by a surface-labelled grating method Reviewed

    Norihisa Akamatsu, Wataru Tashiro, Keisuke Saito, Jun-ichi Mamiya, Motoi Kinoshita, Tomiki Ikeda, Jun Takeya, Shigenori Fujikawa, Arri Priimagi, Atsushi Shishido

    SCIENTIFIC REPORTS   4   2014.6

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    Mechanical properties of flexible films, for example surface strain of largely bending films, are key to design of stretchable electronic devices, wearable biointegrated devices, and soft microactuators/robots. However, existing methods are mainly based on strain-gauge measurements that require miniaturized array sensors, lead wires, and complicated calibrations. Here we introduce a facile method, based on surface-labelled gratings, for two-dimensional evaluation of surface strains in largely bending films. With this technique, we demonstrate that soft-matter mechanics can be distinct from the mechanics of hard materials. In particular, liquid-crystalline elastomers may undergo unconventional bending in three dimensions, in which both the inner and outer surfaces of the bending film are compressed. We also show that this method can be applied to amorphous elastomeric films, which highlights the general importance of this new mechanical evaluation tool in designing soft-matter-based electronic/photonic as well as biointegrated materials.

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  • Photomobile Properties of Interpenetrating Polymer Network Films Composed of Azobenzene Liquid Crystalline Polymer and Polymethacrylates Reviewed

    Toru Ube, Kiyohide Takado, Tomiki Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   594 ( 1 )   86 - 91   2014.5

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    Various fabrication methods of photomobile polymer materials containing photochromic moieties have been developed to improve their photoresponsive and mechanical properties. Here, we newly prepared photomobile polymer materials with interpenetrating polymer network (IPN) structures. The IPN films, which are composed of azobenzene liquid crystalline polymer (LCP) and polymethacrylates, showed reversible bending behavior upon exposure to UV and visible light. Bending speed of the IPN films became higher with decreasing glass-transition temperature of polymethacrylate components. The IPN film containing poly(dodecyl methacrylate) showed faster bending than the pristine azobenzene LCP film.

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  • Function of liquid crystals Invited Reviewed

    Junichi Hanna, Tomiki Ikeda, Toru Ube, Masanori Ozaki, Takashi Kato, Masafumi Yoshio, Atsushi Yoshizawa

    The Liquid Crystal Display Story: 50 Years of Liquid Crystal R and D that Lead the Way to the Future   357 - 410   2014.1

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    An organic semiconductor is material that is capable of transporting a charge, that is, electrons and holes. By this characteristic, that is, the property to support a current flow, they can be used in various electronic devices. In the early 1970s, organic semiconductors have been put to their first practical use in the photosensitive drum of copy machines. Thereafter, it began to be used as a practical material for organic electroluminescent (EL) elements in the 1990s. In recent years, research and development has been actively aimed to practical use in organic solar cells and organic transistors.

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  • Enhancement of mechanical stability in hydrogen-bonded photomobile materials with chemically modified single-walled carbon nanotubes Reviewed

    Tetsuya Ozawa, Mizuho Kondo, Jun-ichi Mamiya, Tomiki Ikeda

    JOURNAL OF MATERIALS CHEMISTRY C   2 ( 13 )   2313 - 2315   2014

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    Uniaxially aligned azobenzene liquid-crystalline polymers crosslinked by hydrogen bonding can deform in response to actinic light. The polymers can be precisely shaped due to high processability of hydrogen-bonded polymers. The mechanical properties of the polymer fibers were improved by introducing single-walled carbon nanotubes as a filler material. Because of weak hydrogen bonding, starting materials can be recovered, reused and recycled, which is very useful in view of chemical resource utilization.

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  • Molecular dynamics in azobenzene liquid crystal polymer films by transient grating technique Reviewed

    Kenji Katayama, Tomomi Fujii, Shota Kuwahara, Takado Kiyohide, Tomiki Ikeda

    LIQUID CRYSTALS XVIII   9182   2014

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    We studied the effect of the ratio between the monomer and cross-linker molecules in the azobenene included liquid crystal polymer films by using the heterodyne transient grating (HD-TG) technique, which is one of the time-resolved measurement techniques. Depending on the ratio, the magnitude of the refractive index change, its anisotropy, and the lifetime of the cis isomer of azobenzene, generated by a UV pulse irradiation. By increasing the cross-linker ratio, the refractive index change and its anisotropy was reduced, indicating less ability for the motion, while slower lifetime was observed by increasing the monomer ratio, indicating that the film is difficult to return the original shape by a visible-light irradiation. The obtained dynamics was consistent with the functionality of the films.

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  • Depth-selective microscopic observation of a photomobile liquid crystal polymer under UV illumination Reviewed

    Kenji Katayama, Youngwoon Choi, Jeon Woong Kang, Zahid Yaqoob, Peter T. C. So, Tomomi Fujii, Shota Kuwahara, Kiyohide Takado, Tomiki Ikeda

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   16 ( 48 )   27074 - 27077   2014

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    By using the depth selective imaging method, we studied the UV induced change in a photomobile liquid crystalline polymer film. With 1 mu m depth resolution, each slice inside the film was selectively observed. A network-like structure mixed with the ordered and disordered regions of molecules in the middle of the film, and a rubbed polymer layer at the bottom of the film were observed. In each slice of the film, the phase change induced by UV light was observed strongly dependent on the director direction, which indicates the ordering change of the liquid crystalline molecules in the director direction. It took several tens of seconds for the ordering change caused by the collaborative interaction between the molecules. Furthermore, it was suggested that the UV induced change travelled from the bottom layer to the middle layer on the micron order.

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  • Liquid-Crystalline Nano-optomechanical Actuator Reviewed

    Stanislav Tsoi, Jing Zhou, Christopher Spillmann, Jawad Naciri, Tomiki Ikeda, Banahalli Ratna

    MACROMOLECULAR CHEMISTRY AND PHYSICS   214 ( 6 )   734 - 741   2013.3

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    The synthesis and characterization of organic nanoparticles composed of a polymer network of azobenzene moieties and capable of reproducible, photoinduced mechanical actuation are reported. The molecules within the nanoparticles undergo co-ordinated, reversible isomerization between cis- and trans-conformations in response to ultraviolet and visible electromagnetic radiation, resulting in a reversible 20% height contraction of nanoparticles adsorbed on a substrate. The kinetics of the actuation response as a function of light intensity and duration are reported and closely match the molecular kinetics of azobenzene photoisomerization. The results support the proposed mechanism of co-ordinated molecular conformational changes resulting in observable nanoscale actuation.

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  • Location of the Azobenzene Moieties within the Cross-Linked Liquid-Crystalline Polymers Can Dictate the Direction of Photoinduced Bending Reviewed

    Priimagi Arri, Shimamura Aki, Kondo Mizuho, Hiraoka Tomohiro, Kubo Shoichi, Mamiya Jun-Ichi, Kinoshita Motoi, Ikeda Tomiki, Shishido Atsushi

    ACS MACRO LETTERS   1 ( 1 )   96 - 99   2012.1

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    We present a simple way to control the photoinduced-bending direction of azobenzene-containing cross-linked liquid-crystalline polymers. By changing the location of the photoactive azobenzene moieties from cross-links to side-chains, the bending direction of the sample is reversed under identical irradiation conditions. In addition to providing a versatile route toward directionality control of the photoinduced macroscopic motions, this observation highlights the complicated nature of the photomechanical response of azobenzene-containing cross-linked liquid-crystalline polymers, showing that the photomobile behavior can be determined by seemingly small details on the materials design.

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  • Synthesis and Emission Behavior of Liquid-Crystalline Main-Chain Polyesters Containing Carbazole and Oxadiazole Moieties Reviewed

    Kinoshita Motoi, Takamura Kenji, Kawamoto Masuki, Shishido Atsushi, Shiono Takeshi, Ikeda Tomiki

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   563   92 - 100   2012

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    Organic light-emitting diodes (OLEDs) based on chromophore-containing liquid crystals (LCs) can emit polarized light due to self-assembly of mesogenic chromophores. The stability of LC phases in LC polymers with a mesogenic group in the main chain is higher than that in the polymers containing a mesogenic group in the side chain.In this study, a novel family of polyesters containing a carbazole moiety as a hole-transporting unit and an oxadiazole (OXD) moiety as an electron-transporting unit in the main chain, P10-DOXDCz and P16-DOXDCz, were designed and synthesized. These polyesters were prepared by transesterification of N-hexyl-3,6-di[2-([1,3,4] oxadiazol-5-yl)- 4-methylbenzoate] carbazole and 1,10-decanediol or 1,16-hexadecanediol at 220 degrees C for 20 h. They showed a nematic phase. Both P10-DOXDCz and P16-DOXDCz emitted intense blue fluorescence with a maximum at 439 nm and 450 nm in thin films, respectively, and their fluorescence quantum yields were 0.74 and 0.81 in solution, respectively. Both compounds exhibited polarized emission in a LC phases, and the order parameters estimated from the polarized emission spectra were 0.10 for P10-DOXDCz and 0.14 for P16-DOXDCz. Fabricated devices, ITO/PEDOT:PSS/P10-DOXDCz and P16-DOXDCz/MgAg, emitted blue light when a positive voltage was applied to the ITO electrode.

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  • Polarized Emission Behavior of Pt Complex-Doped Polymer Films Reviewed

    Kinoshita Motoi, Ibaraki Kenta, Matsuura Yoshihiro, Nam Yunmi, Shishido Atsushi, Ikeda Tomiki

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   563   83 - 91   2012

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    Organic light-emitting diodes (OLEDs) based on conjugated polymers exhibiting polarized emission have attracted much attention because of their potential as backlights for conventional liquid crystal (LC) displays and 3-D displays. We have reported a new series of LC polymers based on donor-acceptor architecture containing an oxadiazole (OXD) and several amine moieties in the same side chain, which exhibit bipolar character with a wide energy band gap.In this study, to develop phosphorescent OLEDs with polarized emission, we synthesized a platinum complex, Pt(4-decyloxy) salen, with emitting property, and fabricated the device consisting of Pt complex as a guest and LC polymers as a host material. The Pt complex exhibited high thermal stability, good solubility and an emission peak at 530 nm in dichloromethane. To obtain electroluminescense from the Pt complex, we fabricated ITO/rubbed PEDOT:PSS/Pt(4-decyloxy) salen: host polymer/MgAg devices. The devices emitted a yellowish green light, which was dominated by the triplet emission of the platinum complex. In addition, polarized electroluminescence was observed in an aligned LC polymer film.

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  • PHOTOINDUCED BENDING UPON PULSED IRRADIATION IN AZOBENZENE-CONTAINING CROSSLINKED LIQUID-CRYSTALLINE POLYMERS Reviewed

    Aki Shimamura, Arri Priimagi, Jun-Ichi Mamiya, Motoi Kinoshita, Tomiki Ikeda, Atsushi Shishido

    JOURNAL OF NONLINEAR OPTICAL PHYSICS & MATERIALS   20 ( 4 )   405 - 413   2011.12

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    We have investigated the photoresponsive behavior of homogeneously aligned low-azobenzene-concentration crosslinked liquid-crystalline polymers. We compared the thermal contraction and photocontraction of the films, and show that upon UV irradiation, they bend efficiently towards the actinic light source. The photoinduced bending is studied both under continuous-wave irradiation and irradiation with nanosecond pulses. Pulsed irradiation revealed that the photomechanical response can take place within sub-millisecond time scale, and that even a single laser pulse can cause the sample to bend.

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  • Simultaneous Analysis of Optical and Mechanical Properties of Cross-Linked Azobenzene-Containing Liquid-Crystalline Polymer Films Reviewed

    Aid Shimamura, Arri Priimagi, Jun-ichi Mamiya, Tomiki Ikeda, Yanlei Yu, Christopher J. Barrett, Atsushi Shishido

    ACS APPLIED MATERIALS & INTERFACES   3 ( 11 )   4190 - 4196   2011.11

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    The photomechanical behavior of cross-linked azobenzene-containing liquid-crystalline polymer films was investigated by means of simultaneous measurement of their optical and mechanical properties. The connection between photoisomerization of the azobenzene moieties, photoinduced change in molecular alignment, photoinduced stress generation, and macroscopic bending was analyzed. Upon UV irradiation, the films exhibited bending due to gradient in cis-azobenzene content, and subsequent unbending when cis-azobenzene content became uniform throughout the film. The maximum photoinduced stress was generated in the same time scale as the time required to reach photostationary state in the cis-azobenzene concentration. The maximum values of photogenerated stress strongly depended on the crosslinker concentration, even if the azobenzene concentration and the cis-azobenzene content in the photostationary state were similar for all the polymer films. The stress is connected to the initial Young's modulus and also to the photoinduced change in birefringence of the polymer films. In addition, a significant photoinduced decrease in Young's modulus was for the first time observed in cross-linked azobenzene-containing liquid-crystalline polymers, which is likely to be an important factor in dictating their photomechanical behavior.

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  • Photomobile polymer materials: from nano to macro Reviewed

    Tomiki Ikeda, Toru Ube

    MATERIALS TODAY   14 ( 10 )   480 - 487   2011.10

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    Modern society is based on the production of energy, primarily, from fossil fuels; however, these resources are limited. Therefore we are now confronted with a difficult problem: producing energy without burning fossil fuels. Many countries have utilized nuclear power to generate electricity as an effective source of energy, such as the US, France, and Japan. However, the tragic disaster at the Fukushima nuclear power station has reminded us that nuclear power is a double-edged sword: it may be a useful energy source, but it can bare its fangs when we lose control. We have many natural energy sources that are present in unlimited quantities, and so are unlikely to be exhausted easily: namely, sunlight, water, and wind. It is thus timely to consider further developing these natural resources to replace nuclear power for the production of energy.

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  • Direct fabrication of photomobile polymer materials with an adhesive-free bilayer structure by electron-beam irradiation Reviewed

    Yumiko Naka, Jun-ichi Mamiya, Atsushi Shishido, Masakazu Washio, Tomiki Ikeda

    JOURNAL OF MATERIALS CHEMISTRY   21 ( 6 )   1681 - 1683   2011

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    Azobenzene liquid-crystalline (LC) polymers coated on a flexible polymer substrate were directly crosslinked by electron beams (EBs). We demonstrated that EB-crosslinked azobenzene LC polymers could successfully work as photomobile polymer materials with an adhesive-free bilayer structure.

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  • Solvent induced amplification of the photoresponsive properties of alpha,omega-di-[4-cyanophenyl-4 '-(6-hexyloxy)-azobenzene]-poly (N-isopropylacrylamide) in aqueous media Reviewed

    Norihito Ishii, Jun-ichi Mamiya, Tomiki Ikeda, Francoise M. Winnik

    CHEMICAL COMMUNICATIONS   47 ( 4 )   1267 - 1269   2011

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    Irradiation at room temperature of alpha,omega-di-[4-cyanophenyl-4'-(6-hexyloxy)-azobenzene]-poly-(N-isopropylacrylamide) (Az(2)-PNIPAM) solutions in water/1,4-dioxane (6 mol% dioxane) reversibly converts a turbid suspension into a clear solution, demonstrating for the first time that cononsolvency of PNIPAM in mixed aqueous solvents in synergy with preferential chromophore solvation can act as actuators of responsive systems.

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  • Analysis of Photoinduced Change in Properties on Macroscopic Motion of Crosslinked Azobenzene Liquid-Crystalline Polymers Reviewed

    Aki Shimamura, Jun-Ichi Mamiya, Atsushi Shishido, Tomiki Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   550   57 - 65   2011

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    Crosslinked azobenzene liquid-crystalline polymer films have been prepared by in-situ photopolymerization, and their photoinduced changes in birefringence and stress on macroscopic motion were investigated. Upon exposure to UV light, the film bent toward an actinic light source along the rubbing direction, and the bent film also reverted to the initial flat state after exposure to visible light at room temperature. Moreover, the birefringence simultaneously decreased and the stress was generated upon UV irradiation. These results indicate that the molecular alignment in the film becomes disordered by trans-cis photoisomerization of the azobenzene moieties and the resultant contraction of the film generates the stress.

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  • Synthesis of Crosslinked Liquid-Crystalline Polymer Brushes on Flexible Polymer Films Toward Photomobile Materials Reviewed

    Y. Naka, J. Mamiya, A. Shishido, T. Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   547   142 - 151   2011

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    We prepared crosslinked azobenzene liquid-crystalline polymer brushes on flexible polymer films by surface-initiated atom transfer radical polymerization and a subsequent crosslinking reaction. Reversible isomerization of azobenzene moieties was observed in the crosslinked films upon irradiation with UV and visible light. Upon exposure to linearly polarized UV light, the films bent slightly along the polarization direction of light toward an actinic light source. After turning off the UV light, the films maintained the bent shape, and then reverted to the initial form by irradiation with visible light. We have successfully developed a novel photomobile material with crosslinked azobenzene liquid-crystalline polymer brushes.

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  • Three-Dimensional Photomobility of Crosslinked Azobenzene Liquid-Crystalline Polymer Fibers Reviewed

    Taiki Yoshino, Mizuho Kondo, Jun-ichi Mamiya, Motoi Kinoshita, Yanlei Yu, Tomiki Ikeda

    ADVANCED MATERIALS   22 ( 12 )   1361 - +   2010.3

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    Crosslinked liquid-crystalline polymer fibers containing azobenzene moieties show three-dimensional movements under photoirradiation (see figure). The direction of the photomobility of the fibers could be controlled by manipulating the actinic light source. The generated stress upon photoinduced bending reached 210 kPa, which is similar to the stress in human muscles.

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  • Preparation of Crosslinked Liquid-Crystalline Polymers by Electron-Beam Irradiation and Their Photoinduced Bending Behavior Reviewed

    Naka Yumiko, Mamiya Jun-ichi, Shishido Atsushi, Washio Masakazu, Ikeda Tomiki

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   529   71 - 79   2010

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    We proposed a new approach to fabricate bilayer films with a crosslinked azobenzene liquid-crystalline (LC) polymer. The polyethylene (PE) substrates were coated with linear azobenzene LC polymers, and then the azobenzene layers were crosslinked by irradiation with electron beams (EBs). In the EB-irradiated films with ordered azobenzene moieties, exposure to UV light caused trans-cis isomerization and the change in alignment of azobenzene moieties. Bending of the bilayer films could be induced toward an actinic light source when they were irradiated from the side of the azobenzene layer, while they bent away from the actinic light source upon UV irradiation from the side of the PE layer. In both cases, the bent films reverted to the initial flat state by turning off the light, which could be repeated at room temperature.

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  • Effect of concentration of photoactive chromophores on photomechanical properties of crosslinked azobenzene liquid-crystalline polymers Reviewed

    Kondo Mizuho, Sugimoto Manabu, Yamada Munenori, Naka Yumiko, Mamiya Jun-ichi, Kinoshita Motoi, Shishido Atsushi, Yu Yanlei, Ikeda Tomiki

    JOURNAL OF MATERIALS CHEMISTRY   20 ( 1 )   117 - 122   2010

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    We studied the effects of concentration and location of azobenzene chromophores on the photoinduced deformation of crosslinked liquid-crystalline polymers (CLCPs). The concentration of azobenzene chromophores in CLCP affects the degree of isomerization of azobenzene moieties and the macroscopic deformation behaviour of the films while the location of azobenzene moieties determines the contraction force and length.

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  • Photoresponsive Behavior of Crosslinked Liquid-Crystalline Polymer Films with a Different Content of an Azobenzene Moiety Reviewed

    Shimamura Aki, Hiraoka Tomohiro, Kondo Mizuho, Kubo Shoichi, Mamiya Jun-ichi, Shishido Atsushi, Ikeda Tomiki

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   529   53 - 59   2010

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    Crosslinked liquid-crystalline polymer films with a different content of an azobenzene moiety were prepared by in-situ photopolymerization, and their photoresponsive behavior was investigated. Observation of the films by polarized absorption spectroscopy and polarizing optical microscopy has revealed that the azobenzene moieties are aligned along the rubbing direction in the films. Upon irradiation with UV light, a film with 5mol% of the azobenzene bent toward an actinic light source along the rubbing direction. The bent film reverted completely to the initial state upon irradiation with visible light. On the other hand, films with 3 and 1mol% of the azobenzene showed no obvious bending by continuous irradiation with UV light. The bent film also reverted to the flat state upon continuous irradiation with UV light.

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  • Synthesis and Association Behavior of Telechelic Poly(N-isopropylacrylamides) with Azobenzene End Groups Reviewed

    Norihito Ishii, Rodolphe Obeid, Xing-Ping Qiu, Jun-ichi Mamiya, Tomiki Ikeda, Francoise M. Winnik

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   529   60 - 70   2010

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    A telechelic poly(N-isopropylacrylamide) (PNIPAM) with azobenzene end-groups (telechelic Az-PNIPAM) was prepared by reversible addition-fragmentation chain transfer (RAFT) free radical polymerization of NIPAM. This polymer self-assembles in cold water forming nanoparticles with a hydrodynamic radius (RH) of 8nm and an aggregation number of 29 chains. The thermoresponsive behavior of Az-PNIPAM in water was investigated by turbidimetry and light scattering. In addition, the photoresponsive behavior of aqueous Az-PNIPAM was investigated by monitoring the changes with temperature of the solution and transmittance at 650nm before and after irradiation at 366nm.

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  • Isomerization Polymerization of 4-Alkylcyclopentenes Catalyzed by Pd Complexes: Hydrocarbon Polymers with Isotactic-Type Stereochemistry and Liquid-Crystalline Properties Reviewed

    Okada Takeshi, Takeuchi Daisuke, Shishido Atsushi, Ikeda Tomiki, Osakada Kohtaro

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   131 ( 31 )   10852 - +   2009.8

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    Isomerization polymerization of 4-alkylcyclopentenes catalyzed by Pd-diimine complexes produces the polymers with trans-1,3-disubstituted cyclopentane rings located regularly along the polymer chain. The polymers with isotactic structure formed by using a C-2-symmetric catalyst exhibited liquid-crystalline properties.

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  • Photomobile polymer materials-various three-dimensional movements Reviewed

    Munenori Yamada, Mizuho Kondo, Ryo Miyasato, Yumiko Naka, Jun-ichi Mamiya, Motoi Kinoshita, Atsushi Shishido, Yanlei Yu, Christopher J. Barrett, Tomiki Ikeda

    JOURNAL OF MATERIALS CHEMISTRY   19 ( 1 )   60 - 62   2009

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    The composition of a crosslinked azobenzene liquid-crystalline polymer and a flexible polymer film can provide a variety of simple devices that can walk in one direction like an 'inchworm' and move like a 'robotic arm' induced by light.

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  • Effect of Recording Time on Grating Formation and Enhancement in an Amphiphilic Diblock Liquid-Crystalline Copolymer Reviewed

    Yu Haifeng, Naka Yumiko, Shishido Atsushi, Iyoda Tomokazu, Ikeda Tomiki

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   498   29 - 39   2009

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    To precisely control the first-order diffraction efficiency of holographic gratings recorded in an amphiphilic diblock liquid-crystalline copolymer P40A37, effect of recording time on grating formation and enhancement was studied systematically. Several parameters such as surface relief, the first-order diffraction efficiency, the maximum transmittance under an optical polarizing microscope and order parameters of grating samples were evaluated before and after annealing. Then the enhancement coefficient with recording time was estimated. The best enhancement effect was obtained at 10-s recording upon nano-scaled phase separation. By precisely adjusting the recording time, the diffraction efficiency of holographic gratings in P40A37 can be finely controlled from 0.13% to 10%.

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  • Photomechanical properties of azobenzene liquid-crystalline elastomers Reviewed

    Mizuho Kondo, Ryo Miyasato, Yumiko Naka, Jun-ichi Mamiya, Motoi Kinoshita, Yanlei Yu, Christopher J. Barrett, Tomiki Ikeda

    LIQUID CRYSTALS   36 ( 10-11 )   1289 - 1293   2009

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    We prepared homogeneously aligned azobenzene liquid-crystalline elastomer (LCE) films with low Tg and explored their photomechanical properties. Upon irradiation with UV light, the films bent toward a light source at room temperature. The mechanical force generated upon exposure to UV light was evaluated by thermomechanical analysis. It was found that the mechanical force generated by photo-irradiation increased with an increase in the cross-linking density. In particular, an LCE film containing 80 mol% azobenzene cross-linker produced a force of over 1 MPa by photo-irradiation, which enabled the film to lift an object 20 times heavier than itself. The degree of contraction by photo-irradiation increased with an increase in temperature and light intensity. Bending could be brought about by more than 5000 times with periodic irradiation. Furthermore, it was found that the LCE films exhibited bending and unbending behaviour by irradiation with sunlight.

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  • Fabrication of a Liquid Crystal Microlens Array Film with Oligothiophene-Doped Polymerizable Liquid Crystals Reviewed

    Kinoshita Motoi, Kobayashi Tomohiro, Shishido Atsushi, Ikeda Tomiki

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   511   1768 - 1778   2009

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    Fabrication of a microlens array film was explored by means of photoinduced reorientation of dye-doped polymerizable liquid crystals (LCs). LC monomer/photoinitiator mixtures doped with a small amount of an oligothiophene derivative were irradiated with a 488-nm beam from an Ar+ laser. Then the sample cell was periodically moved. After these two processes were repeated for a few tens times, remaining photoinitiators were quenched by irradiation with UV light. Observation of the cells with a polarizing optical microscope revealed that the molecular alignment of LCs induced by the Ar+ laser beam remained unchanged after the beam was turned off and a microlens array with a square-lattice type was obtained. This indicates that formation of the microlens and photopolymerization of the LC monomers are brought about simultaneously in a small area. The fabricated microlens has polarization selectivity that reflects molecular alignment. The focal length of the microlens arrays could be changed by controlling the irradiation intensity. Furthermore, a freestanding film with microlens arrays was obtained by peeling from the sample cell.

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  • Photoalignment and Holographic Properties of Azobenzene-Containing Block Copolymers with Oxyethylene and Alkyl Spacers Reviewed

    Naka Yumiko, Yu Haifeng, Shishido Atsushi, Ikeda Tomiki

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   513   131 - 141   2009

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    Two azobenzene-containing block copolymers with an oxyethylene (P1) or an alkyl (P2) spacer in the side chain were prepared by atom transfer radical polymerization (ATRP). Neither of the block copolymers with a low azobenzene content showed a liquid-crystalline phase. However, their glass transition temperatures (T(g)s) were lowered by introducing flexible spacers. In particular, T-g was lowered by about 30 degrees C in P1. Their photoalignment and holographic behavior was investigated at various temperatures in thin films. Rapid changes in refractive index were induced in the P1 films upon irradiation at a temperature below T-g. But the photoinduced birefringence in the P1 film was lower than that in the P2 films. Similar results were obtained in holographic recording. The azobenzene-containing block copolymer with the oxyethylene spacer (P1) used in this study has potential application for dynamic hologram.

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  • Photoresponsive and Holographic Behavior of an Azobenzene-Containing Block Copolymer and a Random Copolymer Reviewed

    Naka Yumiko, Yu Haifeng, Shishido Atsushi, Ikeda Tomiki

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   498   118 - 130   2009

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    A block copolymer containing an azobenzene (Az) moiety in the side chain was prepared by atom transfer radical polymerization (ATRP). For comparison, a random copolymer with a similar Az content was also designed. Their photoresponsive and holographic behavior was investigated in thin films. The block copolymer film showed microphase separation with cylinder microdomains after annealing, which was then irradiated at 366 nm. It was found that trans-cis photoisomerization in the block copolymer film was slower than that in the random copolymer film. This may be due to the restricted motion of the Az moieties in the Az blocks. The photoinduced birefringence (Delta n) of the block copolymer film was higher than that of the random copolymer film upon irradiation with a linearly polarized beam. In holographic recording, similar results were obtained. A block copolymer with 22-mol% Az showed a liquid-crystalline (LC) phase, while a random copolymer with 24-mol% Az exhibited no LC phase. The block copolymer showed an LC phase at a lower Az content compared with the random copolymer, suggesting that the molecular alignment of Az mesogenic groups is enhanced by cooperative motion of LCs in block copolymer films.

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  • Photoresponsive Behavior of Laminated Films Composed of a Flexible Plastic Sheet and a Crosslinked Azobenzene Liquid-Crystalline Polymer Layer with Different Initial Alignment of Mesogens Reviewed

    Munenori Yamada, Mizuho Kondo, Ryo Miyasato, Jun-ichi Mamiya, Motoi Kinoshita, Yanlei Yu, Christopher J. Barrett, Tomiki Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   498   65 - 73   2009

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    Laminated films composed of a flexible plastic sheet and a crosslinked azobenzene liquid-crystalline polymer (CLCP) layer with different initial alignment of azobenzene mesogens were prepared by thermal compression bonding of a CLCP film and an unstretched low-density polyethylene (PE) film with an adhesion layer. In both laminated films with a homogeneous alignment of mesogens and a homeotropic one, large movements could be induced by irradiation with UV light at room temperature. A partly laminated film with homogeneous CLCP bent from both ends of the whole film, while one with homeotropic CLCP bent up from the center of the film toward the light source. These results indicate that we enable plastic films with no photoresponsive property to move flexibly upon photoirradiation just by laminating the CLCP layers partly, and the photoinduced motions of the laminated films are completely dependent on the alignment direction of the mesogens in the CLCP layers. In addition, it was found that the maximum stress generated in the films and the stress increment are also different between the homogeneous CLCP laminated films and the homeotropic ones.

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  • Phosphorescent PLEDs Using Donor-Acceptor Liquid-Crystalline Polymers Containing Oxadiazole and Carbazole Reviewed

    Yunmi Nam, Yoshihiro Matsuura, Motoi Kinoshita, Tomiki Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   513   142 - 152   2009

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    Blue-emitting polymers based on a donor-acceptor architecture composed of oxadiazole and carbazole moieties containing various substituted groups in the same side chain were used as a host polymer in phosphorescent polymer light-emitting diodes (PhPLEDs). The polymer containing N-methylcarbazole showed a liquid-crystalline (LC) phase above its glass transition temperature but the other polymer containing N-ethylhexylcarbazole exhibited an amorphous phase. The single-layer PLEDs using these polymers exhibited blue emission with peaks from 430 to 440 nm. To examine the LC polymer (LCP) and the amorphous polymer as host materials, we fabricated simple devices using Ir(ppy)(3) and (btp)(2)lr(acac) as phosphorescent dopants at various doping concentrations. The device composed of lTO/PEDOT-PSS/2wt% of (btp)(2)Ir(acac) doped into LCP/MgAg showed intense red light (0.67, 0.32) with the luminance efficiency of 4.7 cd/A. The luminance efficiency of the PhPLEDs using the LCP was higher than that of the PhPLEDs using the amorphous polymer.

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  • Well-Defined Liquid-Crystalline Diblock Copolymers with an Azobenzene Moiety: Synthesis, Photoinduced Alignment and their Holographic Properties Reviewed

    Yu Haifeng, Naka Yumiko, Shishido Atsushi, Ikeda Tomiki

    MACROMOLECULES   41 ( 21 )   7959 - 7966   2008.11

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    A series of liquid-crystalline (LC) diblock copolymers with an azobenzene moiety in the side chain were prepared by atom transfer radical polymerization (ATRP). Using a bromo-terminated poly(methyl methacrylate) as a macroinitiator, the obtained diblock copolymers showed well-defined structures and narrow molecular-weight distributions. Microphase-separated nanostructures with mesogenic blocks in either continuous or separated phases were observed. Owing to varied content of mesogens in the block copolymers, they showed different behavior of photoinduced alignment and holographic recording. Block copolymers with azobenzenes in the majority phases exhibited a similar performance of photoinduced alignment and refractive-index modulation to the azobenzene-containing homopolymer, but their photoinduced mass transportation was partly suppressed by the microphase separation, leading to a lower surface relief than that of the homopolymer. The photoinduced mass transfer was greatly prohibited in the block copolymers with mesogenic groups in the minority phases, resulting in little surface relief. However, refractive-index gratings were still recorded upon local alignment, driven by the photoinduced alignment of azobenzenes or the phototriggered molecular cooperative motion between azobenzenes and nonphotosensitive cyanobiphenyl groups. Then the possible schematic illustrations of mesogens and microphase separation in the grating structures were proposed.

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  • Random Copolymerization of Norbornene with Higher 1-Alkene with ansa-Fluorenylamidodimethyltitanium Catalyst Reviewed

    Takeshi Shiono, Mitsunori Sugimoto, Tariqul Hasan, Zhengguo Cai, Tomiki Ikeda

    MACROMOLECULES   41 ( 22 )   8292 - 8294   2008.11

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    DOI: 10.1021/ma802119d

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  • Azo Block Copolymers in the Solid State Reviewed

    Haifeng Yu, Tomiki Ikeda

    Smart Light-Responsive Materials: Azobenzene-Containing Polymers and Liquid Crystals   411 - 456   2008.8

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    DOI: 10.1002/9780470439098.ch12

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  • Photodeformable Materials and Photomechanical Effects Based on Azobenzene-Containing Polymers and Liquid Crystals Reviewed

    Yanlei Yu, Tomiki Ikeda

    Smart Light-Responsive Materials: Azobenzene-Containing Polymers and Liquid Crystals   95 - 144   2008.8

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    Language:English   Publishing type:Part of collection (book)   Publisher:John Wiley & Sons, Inc.  

    DOI: 10.1002/9780470439098.ch3

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  • Subwavelength modulation of surface relief and refractive index in preirradiated liquid-crystalline polymer films Reviewed

    Yu Haifeng, Shishido Atsushi, Ikeda Tomiki

    APPLIED PHYSICS LETTERS   92 ( 10 )   2008.3

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER INST PHYSICS  

    We present a simple method to record subwavelength gratings (SWGs) in an azobenzene (AZ)-containing liquid-crystalline polymer by preirradiation. Since the cooperative motions of mesogens are eliminated in a cis-AZ-rich isotropic phase by the pretreatment, the subwavelength modulation of surface relief and refractive index (RI) was obtained. The surface relief of less than 10 nm and the RI modulation were detected by atomic force microscopy. A large phase retardation and formed birefringence were obtained in the recorded SWGs in which a possible schematic illustration of AZ was proposed. (C) 2008 American Institute of Physics.

    DOI: 10.1063/1.2894073

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  • Controlled Homeotrophic and Homogeneous Orientations for Nanoscale PhaseSeparated Domain Reviewed

    Atsunori Mori, Junichi Shikuma, Motoi Kinoshita, Tomiki Ikeda, Masahiro Misaki, Yasukiyo Ueda, Sadayuki Asaoka, Tomokazu Iyoda

    Chemistry Letters   Vol. 37, No. 3, pp. 272-273 ( 3 )   272 - 273   2008.3

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:CHEMICAL SOC JAPAN  

    An amphiphilic block copolymer composed of poly(ethylene oxide) and poly(methacrylate ester) bearing a donor-acceptor-type 2,5-diarylthiazole in the side chain is prepared by atom-transfer radical polymerization. The precursor 2,5-diarylthiazole monomer is prepared by transition-metal-catalyzed CH arylation reactions. A thin film of the block copolymer formed by spin coating exhibited nanoscale phase separation with homeotropically oriented domains, while a film formed by the friction transfer method showed domains with homogeneous orientation confirmed by AFM. Spectroscopic studies of the film, utilizing the luminescent characteristics of 2,5-diarylthiazole, showed polarized light emission as a result of the liquid crystalline ordering.

    DOI: 10.1246/cl.2008.272

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  • Homo- and copolymerization of norbornene derivatives with ethene by ansa-fluorenylamidodimethyltitanium activated with methylaluminoxane Reviewed

    Tariqul Hasan, Tomiki Ikeda, Takeshi Shiono

    JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY   45 ( 20 )   4581 - 4587   2007.10

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-BLACKWELL  

    (t-BuNSiMe(2)Flu)TiMe(2) (1) activated with Me(3)Al-free methylaluminoxane (dried MAO) which conducts vinyl addition polymerization of norbornene (N) with very high activity was applied for homopolymerization of N derivatives (i.e., 5-vinyl2-norbornene (5V2N), 5-ethylidene-2-norbornene (MN), dicyclopentadiene (DCPD)) at 40 degrees C. The activities for the N derivatives were about two orders of magnitude lower than that for N and decreased in the following order: 5E2N > 5V2N > DCPD. Copolymerization of ethene (E) and 5E2N under an atmospheric pressure of E was then conducted by 1-dried MAO. The copolymerization proceeded with better activity than the homopolymerization of 5E2N and gave poly(E-co-MN) with narrow molecular weight distribution. The content of the ethylidene group in poly(E-co-5E2N) was controlled by the feed ratio of 5E2N/E. The T(g) value of the copolymer changed from 70 degrees C to 155 degrees C according to the 5E2N content from 27 mol % to 68 mol %. The addition of N as a third monomer to the E-5E2N copolymerization improved the activity and raised the Tg values of the terpolymer above 200 degrees C. The content of 5E2N was controlled by the 5E2N/N ratio with keeping the high Tg values. (c) 2007 Wiley Periodicals, Inc.

    DOI: 10.1002/pola.22193

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  • Circular arrangement of mesogens induced in Bragg-type polarization holograms of thick azobenzene copolymer films with a tolane moiety Reviewed

    Shishido Atsushi, Ishiguro Makoto, Ikeda Tomiki

    CHEMISTRY LETTERS   36 ( 9 )   1146 - 1147   2007.9

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    Bragg-type polarization holograms were recorded in thick copolymer films with tolane and azobenzene moieties by interfering two orthogonal circularly polarized beams at 488 rim. Observation of the films with a polarizing optical microscope revealed that circular alignment of molecules was induced along a grating vector. An incident reading beam at 633 nm was efficiently diffracted, depending on its polarization state and incident direction.

    DOI: 10.1246/cl.2007.1146

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  • Synthesis and properties of photo-cross-linkable hyperbranched poly(urethane)s containing both terminal methacryloyl groups and carboxyl groups Reviewed

    Maruyama Ken, Kudo Hiroto, Ikehara Takayuki, Nishikubo Tadatomi, Nishimura Isao, Shishido Atsushi, Ikeda Tomiki

    MACROMOLECULES   40 ( 14 )   4895 - 4900   2007.7

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    The synthesis and photopolymerization of alkaline-developable hyperbranched polyurethane (HBPUMA-COOH) were examined. The reaction of dicyclohexylmethane 4,4'-diisocyanate (CMDI) and trimethylolpropane (TMP) in the presence of 2-methacryloyloxyethyl isocyanate (MOI) was carried out to give the soluble hyperbranched polyurethane (HBPUMA) with terminal methacryloyl groups in satisfactory yield. After that, HBPUMA-COOH was synthesized by the reaction of HBPUMA and cis-1,2,3,6-tetrahydrophthalic anhydride (THPA). The photoradical polymerization of HBPUMA-COOH was examined in the presence of 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-2-one (Irgacure 907) as a photoinitiator in the film state upon UV irradiation to afford the corresponding cured film quantitatively. It was found that the tensile strength of the resulting cured film of HBPUMA-COOH was higher than those of the HBPUMA and linear one. The negative patterning property of HBPUMA-COOH also had 5 mu m line and space pattern resolution by UV irradiation with 150 mJ/cm(2). Furthermore, it was cleared that the photocured HBPUMA and HBPUMA-COOH showed very low birefringence.

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  • Azobenzene liquid-crystalline polymer for optical switching of grating waveguide couplers with a flat surface Reviewed

    Bang Chong-Uk, Shishido Atsushi, Ikeda Tomiki

    MACROMOLECULAR RAPID COMMUNICATIONS   28 ( 9 )   1040 - 1044   2007.5

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    Grating waveguide couplers with a flat surface were fabricated in an azobenzene liquid-crystalline polymer film by holographic lithography using Ar+ laser beams at 488 nm. When a probe beam at 633 nm was incident to one grating of a grating waveguide coupler, the beam propagated in the waveguide and an output beam came out from the other grating with the throughput coupling efficiency of approximate to 5%. Upon irradiation of the film between two gratings with UV light to cause trans-cis photoisomerization of the azobenzene moiety, the intensity of the output beam was repeatedly switched. It was found that the alternating irradiation at 366 and 436 nm induced reversible changes in the intensity of the guided probe beam.

    DOI: 10.1002/marc.200700041

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  • Photoinduced nanoscale cooperative motion in a well-defined triblock copolymer Reviewed

    Yu Haifeng, Asaoka Sadayuki, Shishido Atsushi, Iyoda Tomokazu, Ikeda Tomiki

    SMALL   3 ( 5 )   768 - 771   2007.5

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    DOI: 10.1002/smll.200600724

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  • Novel wormlike nanostructures self-assembled in a well defined liquid crystalline diblock copolymer with azobenzene moieties Reviewed

    Yu Haifeng, Shishido Atsushi, Iyoda Tomokazu, Ikeda Tomiki

    MACROMOLECULAR RAPID COMMUNICATIONS   28 ( 8 )   927 - 931   2007.4

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    Novel wormlike nanostructures were self-assembled in bulk films of a well defined diblock copolymer with azobenzene moieties, which was prepared by atom transfer radical polymerization (ATRP). For comparison, a homopolymer with almost the same repeat units of azobenzene as those in the copolymer was also prepared. They both had well defined structures and exhibited a smectic liquid crystalline phase. Upon annealing the copolymer films, poly (methyl methacrylate) formed a matrix with excellent optical properties, and the azobenzene segment in the minority phase self-assembled into a wormlike mesogenic domain in the bulk films. Such block copolymer films exhibited stability and transparency by eliminating the scattering of visible light, indicating their potential application as photoresponsive functional materials. Although wormlike morphologies have been obtained in micelles from block copolymer solutions, to the best of our knowledge, such wormlike nanostructures have never been explored in bulk films.

    DOI: 10.1002/marc.200600901

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  • Direct fabrication of microlens arrays with polarization selectivity Reviewed

    Yaegashi Masahiro, Kinoshita Motoi, Shishido Atsushi, Ikeda Tomiki

    ADVANCED MATERIALS   19 ( 6 )   801 - +   2007.3

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    Fabrication of microlens arrays (see figure) is explored using photoinduced reorientation of dye-doped liquid crystals and successive photopolymerization with a single laser beam by selecting a suitable photoinitiator. Each microlens in the microlens array exhibits polarization selectivity with respect to the incident polarized light, and the arrays can be arranged in desired patterns and with desired polarization directions.

    DOI: 10.1002/adma.200601329

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  • Photoinduced alignment and multi-processes of refractive-index gratings in pre-irradiated films of an azobenzene-containing liquid-crystalline polymer Reviewed

    Yu Haifeng, Shishido Atsushi, Iyoda Tomokazu, Ikeda Tomiki

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   470   71 - 81   2007

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:TAYLOR & FRANCIS LTD  

    After being pre-treated upon irradiation of unpolarized light at 366 nm, an azobenzene-containing liquid-crystalline polymer film was photoinduced alignment by one linearly polarized laser beam at 488 nm, leading to a large birefringence of 0.21. Then holographic gratings were recorded in the pre-irradiated polymer films by interference of two coherent laser beams. Little surface relief was obtained by the holographic recording process, indicating that a refractive-index grating paid most of contributions to the diffraction efficiency. Because the cooperative motion of the azobenzene mesogens were eliminated in the cis-azobenzene-rich isotropic film by the pre-irradiation, multi-processes of the refractive-index gratings were successfully achieved. The obtained grating structures were clearly shown in the polarizing optical microscopic pictures, which were also verified by their diffraction patterns. The azobenzene-containing liquid-crystalline polymer used in this study has potential application in high-density information storage.

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  • Photoinduced deformation Behavior of crosslinked azobenzene liquid-crystalline polymer films with unimorph and bimorph structure Reviewed

    Mizuho Kondo, Jun-ichi Mamiya, Motoi Kinoshita, Tomiki Ikeda, Yanlei Yu

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   478   1001 - 1013   2007

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    The use of a crosslinked azobenzene liquid-crystalline polymer (CALP) system for micro-integrated actuators becomes especially attractive. CALPs can deform. along the alignment direction of mesogens upon irradiation of UV/visible light owing to photochemical phase transition. In this study, to improve the bending speed, CALP films with a homogenous alignment on one surface and a homeotropic alignment on the opposite surface (hybrid alignment) were prepared and their bending behavior was investigated. The films showed photoinduced bending whose direction was determined by the surface alignment treatments and the bending speed was greatly enhanced upon irradiation from both surfaces of the film at the same time.

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  • Preparation and characterization of crosslinked liquid-crystalline polymer films with a long Spacer Reviewed

    Jixiang Xu, Ruoyuan Yin, Yanlei Yu, Weiru Wang, Tomiki Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   470   83 - 91   2007

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    Three azobenzene acrylate monomers containing alkyl spacers of different length were synthesized. Thermodynamic and mesomorphic properties of the monomers were measured by differential scanning calorimetry and polarizing optical microscopy. A crosslinker with the undecyl spacer was also synthesized to prepare crosslinked liquid-crystalline polymer films by photopolymerization. Polarized UV spectra and polarizing optical micrographs demonstrated that the mesogens are aligned homogeneously in the films. Low glass transition temperature of the films enabled them to bend near room temperature upon UV irradiation. Besides, the films generally bent away from the light source before they at last bent towards the light irradiation.

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  • Preparation and characterization of crosslinked azobenzene liquid-crystalline polymer fibers Reviewed

    Taiki Yoshino, Jun-ichi Mamiya, Motoi Kinoshita, Tomiki Ikeda, Yanlei Yu

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   478   989 - 999   2007

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    We report the synthesis and physical properties of crosslinked liquid-crystalline polymer (CLCP) fibers consisting of a liquid-crystalline monomer and all acrylate monomer with a hydroxyl group that acts (is a reactive site for crosslinking. By differential scanning calorimetry, the CLCP fibers showed a glass transition temperature around 60 degrees C. Polarizing optical microscopy revealed that we obtained fibers with high orientation of mesogens along the fiber axis. The CLCP fibers showed deformations induced by heated the fiber to all isotropic phase.

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  • High-performance rewritable bragg hologram with high multiplicities Reviewed

    Atsushi Shishido, Tomiki Ikeda

    LIQUID CRYSTALS AND APPLICATIONS IN OPTICS   6587   2007

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:SPIE-INT SOC OPTICAL ENGINEERING  

    Azobenzene-containing polymer, in which a change in birefringence can be induced by photoisomerization, is one of promising materials for holographic applications. To develop high-performance holographic materials using azobenzene polymers, it is necessary to prepare optically transparent thick films with capability of a large photoinduced change in refractive index to obtain high diffraction efficiency and fast response in the Bragg regime. A number of materials have been studied so far, but no attention has been paid to the combination of thick amorphous copolymers films containing photoresponsive and mesogenic groups in the side chain and polarization gratings formed in the Bragg regime. In this paper, we prepared optically transparent thick polymer films containing an azobenzene moiety with photosensitivity and a tolane moiety with high birefringence, and formed intensity and polarization gratings with linearly polarized beams and orthogonal circularly polarized beams, respectively. It was found that the nearly theoretically maximum diffraction efficiency was successfully achieved, and the recorded hologram could be erased thermally or photochemically. In addition, a large change in refractive index was induced in the polarization grating, and high diffraction efficiency (similar to 90%) and quick response (920 ms) was realized simultaneously.

    DOI: 10.1117/12.722666

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  • Fabrication of liquid crystal microlens arrays using dye-doped polymerizable liquid crystals Reviewed

    Motoi Kinoshita, Tomohiro Kobayashi, Michitsugu Yagi, Tomiki Ikeda

    JOURNAL OF PHOTOPOLYMER SCIENCE AND TECHNOLOGY   20 ( 1 )   91 - 92   2007

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:TECHNICAL ASSOC PHOTOPOLYMERS,JAPAN  

    DOI: 10.2494/photopolymer.20.91

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  • Stable macroscopic nanocylinder arrays in an amphiphilic diblock liquid-crystalline copolymer with successive hydrogen bonds Reviewed

    Yu Haifeng, Shishido Atsushi, Li Jingze, Kamata Kaori, Iyoda Tomokazu, Ikeda Tomiki

    JOURNAL OF MATERIALS CHEMISTRY   17 ( 33 )   3485 - 3488   2007

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

    In bulk films of a novel well-defined amphiphilic diblock liquid-crystalline copolymer with aramid moieties, a stable perpendicularly orientated hydrophilic nanocylinder array with hexagonal packing was formed in a large area by supramolecular self-assembly.

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  • Photoluminescent and liquid-crystalline properties of donor-acceptor-type 2,5-diarylthiazoles Reviewed

    Shikuma J, Mori A, Masui K, Matsuura R, Sekiguchi A, Ikegami H, Kawamoto M, Ikeda T

    Chemistry-an Asian Journal   2 ( 2 )   301 - 305   2007

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    The synthesis of donor-acceptor-type 2,5-diarylthiazoles that bear electron-donating NN-dialkylamine and electron-withdrawing cyano groups at the 2- and 5-position, respectively, were carried out with transition-metal-catalyzed C-H arylation reactions developed by us. The compounds were synthesized by the C-H arylation of unsubstituted thiazole at the 2-position with a palladium/copper catalyst in the presence of tetrabutylammonium fluoride (TBAF) as an activator. Further C-H arylation of the 2-arylated thiazole at the 5-position was carried out by the palladium-catalyzed reaction in the presence of silver(I) fluoride to afford the donor-acceptor-type 2,5-diarylthiazoles with NN-dialkylamine groups of different chain lengths. The UV/Vis absorption, photoluminescence, and electrochemical behavior were similar regardless of chain length, whereas liquid-crystalline behavior and thermal characteristics were found to be dependent on the alkyl-chain length. The compounds with NN-diethylamine or N-butyl-N-methyl groups showed a stable liquid-crystalline phase over a wide temperature range as well as higher stability to thermal decomposition.

    DOI: 10.1002/asia.200600305

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  • Preparation and photoresponsive behavior of plastic films coated with azobenzene liquid-crystal line polymer layers Reviewed

    Munenori Yamada, Rie Okutsu, Jun-ichi Mamiya, Motoi Kinoshita, Tomiki Ikeda, Yanlei Yu

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   470   93 - 100   2007

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:TAYLOR & FRANCIS LTD  

    Plastic films coated with crosslinked liquid-crystalline polymer (CLCP) layers containing azobenzene moieties (plastic/CLCP bilayer films) were prepared by thermal polymerization of mixtures of an azobenzene monomer and a crosslinker placed between a plastic film and a glass substrate. When the glass substrate was untreated, the obtained bilayer film bent slightly away from the UV light source when irradiated on the CLCP layer side. This bending direction was the same as that of a hybridly aligned CLCP film. When the glass substrate was coated with a rubbed polyimide to strengthen the homogeneous alignment of the azobenzene moieties of the CLCP surface layer, the obtained bilayer film bent toward the irradiation direction of the incident UV light. It was the same as a homogeneously aligned CLCP film and the degree of bending was larger than that of the untreated sample. This means that the photoinduced bending behavior of the plastic/CLCP bilayer films strongly depends on the alignment of the azobenzene moieties of the CLCP surface layer facing the incident light.

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  • Control of regular nanostructures self-assembled in an amphiphilic diblock liquid-crystal line copolymer Reviewed

    Yu Haifeng, Li Jingze, Shishido Atsushi, Iyoda Tomokazu, Ikeda Tomiki

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   478   1027 - 1037   2007

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:TAYLOR & FRANCIS LTD  

    An amphiphilic diblock liquid-crystalline copolymer consisting of poly(ethylene oxide) (PEO) and polymethacrylate containing an azobenzene moiety in the side chain was prepared by atom transfer radical polymerization (ATRP). The specifically-designed chemical constitution and the low molecular-weight polydispersity enable the block copolymer to form a regular microphase-separated nanostructure self-assembled in its bulk films, in which a hexagonal packing of the PEO cylinders normal to the substrates was dispersed in a continuous phase of azobenzene mesogens with out-of-plane alignment. Then a commerically available rubbing technique was first used to control the microphase-separated domains in the copolymer films, By introducing novel supramolecular cooperative motions between ordered azobenzene mesogens and PEO microphase domains, macroscopic array of PEO nanocylinders was regularlly formed along the rubbing direction. Both the clotted and parrallel stripe patterns of PEO nanocylinders were successfully obtained in the same block copolymer.

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  • Synthesis and photoresponsive behavior of a liquid-crystalline polymer with a 4-ring azotolane moiety with huge birefringence Reviewed

    Okano Kunihiko, Shishido Atsushi, Ikeda Tomiki

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   478   1015 - 1025   2007

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:TAYLOR & FRANCIS LTD  

    A novel liquid-crystalline polymer (LCP) containing an azobenzene group directly connected to a tolane moiety (azotolane moiety) was synthesized. The LCP showed a nematic phase in a broad temperature range (>200 degrees C). Trans-cis photoisoinerization and cis-trans thermal isonterization occurred even though the LCP contains a long azotolane moiety. The homogeneously aligned film of the LCP exhibited an. extremely large value of Delta n (0. 70 at 633 nm). Upon irradiation with a pumping beam in the LC phase, a large change in An was induced due to destruction of the homogeneous alignment of the azotolane moieties.

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  • Synthesis of uniquely branched polyethylene by anilinonaphthoquinone ligated nickel complex activated with tris(pentafluorophenyl)borane Reviewed

    Mitsuhiro Okada, Yuushou Nakayama, Tomiki Ikeda, Takeshi Shiono

    MACROMOLECULAR RAPID COMMUNICATIONS   27 ( 17 )   1418 - 1423   2006.9

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    A novel nickel complex ligated with 2-(2,6-diisopropylanilino)-1,4-naphthoquinone (1) was synthesized. The molecular structure of 1 determined by X-ray analysis was a square-planar geometry. Complex 1 conducted ethylene polymerization at 40 degrees C in a low activity to give linear polyethylene. On the other hand, 1 activated with 4 eq. of B (C(6)F(5))(3) was highly active for ethylene polymerization and gave a polymer possessing short chain branches of methyl, ethyl and propyl groups formed by a chain walking mechanism, as well as long chain branches, of which the content was almost the same as the total content of short chain branches. These results suggest that the macromonomer formed via beta-hydride elimination should have effectively copolymerized with ethylene to give the long chain branches in the B(C(6)F(5))(3)-activated system.

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  • Propene Polymerization by ansa-Fluorenylamidodimethyltitanium Activated with SiO2-Supported Modified Methylalminoxane Reviewed

    Takeshi Shiono, Takashi Matsumae, Kei Nishii, Tomiki Ikeda

    PROGRESS IN OLEFIN POLYMERIZATION CATALYSTS AND POLYOLEFIN MATERIALS, PROCEEDINGS OF THE FIRST ASIAN POLYOLEFIN WORKSHOP   161   241 - 244   2006

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:ELSEVIER SCIENCE BV  

    SiO2-supported cocatalyst was prepared from trialkylaluminium-free modified methylaluminoxane. Propene polymerization was performed by [t-BuNSiMe2(Flu)]TiMe2 combined with the prepared cocatalyst in heptane. The supported system showed a comparable initial activity to the corresponding homogeneous system that conducts living polymerization of propene and gave the polymer with higher molecular weight and broader molecular weight distribution. Deactivation and chain transfer reaction however occurred in the supported system.

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  • Surface relief grating couplers using azobenzene liquid-crystalline polymer films Reviewed

    Chong-Uk Bang, Atsushi Shishido, Tomiki Ikeda, Hideo Kurihara

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   458   149 - 159   2006

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:TAYLOR & FRANCIS LTD  

    Input and output grating couplers with a grating period of 1.3 mu m were fabricated in an azobenzene liquid-crystalline polymer film by holography. When a He-Ne laser beam at 633 nm was incident to the input grating, the beam was coupled, propagated in the polymer film, and then was taken out from the output grating. The coupling efficiency of the input and output coupler was estimated as about 1.1% in TE mode. Upon irradiation of the film with UV light to cause trans-cis photoisomerization of the azobenzene moiety, the intensity of the output beam was repeatedly changed.

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  • Substituent effects of tert-butyl groups on fluorenyl ligand in syndiospecific living polymerization of propylene with ansa-fluorenylamidodimethyltitanium complex Reviewed

    ZG Cai, T Ikeda, M Akita, T Shiono

    MACROMOLECULES   38 ( 20 )   8135 - 8139   2005.10

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    [t-BuNSiMe2(2,7-t-Bu(2)Flu)]TiMe2 and [t-BuNSiMe2(3,6-t-Bu(2)Flu)]TiMe2 were synthesized and characterized by elemental analysis, H-1 NMR, and single-crystal X-ray analysis. These complexes were applied for propylene polymerization using dried modified methyaluminoxane (dMNIAO) as a cocatalyst at 0 and 25 degrees C. The introduction of tert-butyl substituents to the fluorenyl ligand improved the activity more than 3 times regardless of the position of the substituents. The postpolymerization testified that both catalytic systems conducted the propylene polymerization in a living manner at both 0 and 25 degrees C. The propagation rate increased linearly against the Al/Ti ratio from the range of 100-400 with keeping the number of polymer chains constant, which directly indicates that a larger amount of dMMAO enhanced the propagation rate. The introduction of tert-butyl substituents also improved the syndiospecificity: the 3,6-position was more effective than the 2,7-position, and [t-BuNSiMe2(3,6-t-Bu(2)Flu)]TiMe2 gave the living polypropylene with the syndiotactic triad of 0.93 and the melting point of 142 degrees C.

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  • Evaluation of photoinduced change in refractive index of a polymer film doped with an azobenzene liquid crystal by means of a prism-coupling method Reviewed

    H Kurihara, A Shishido, T Ikeda

    JOURNAL OF APPLIED PHYSICS   98 ( 8 )   2005.10

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    The photoinduced change in refractive index of poly(methyl methacrylate) films doped with an azobenzene liquid crystal was measured by the prism-coupling method. Upon irradiation of the film with a high-pressure mercury lamp at 366 nm, the coupling angles shifted and then recovered to the initial position by turning off the light. The change in refractive index was found to be 2x10(-3), which is attributed to the reversible photoisomerization of the azobenzene moieties.

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  • Morphology control of oxadiazole compounds by introduction of amine moieties Reviewed

    H Mochizuki, T Hasui, T Ikeda

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   44 ( 1B )   485 - 490   2005.1

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    Three oxadiazole derivatives with an amine and an alkyl tail were designed and synthesized as novel photo- and electro-active materials: 2-(4'-propylbiphenyl-4-yl)-5-(4-N,N-dimethylaminophenyl-4-yl)-1,3,4,-oxadiazole (3-OXD-Me), 2- (4'-heptybiphenyl-4-yl)-5-(4-N,N-dimethylaminophenyl-4-yl)-1,3,4,-oxadiazole (7-OXD-Me), 2-(4'-heptylbiphenyl-4-yl)-5-(4-N,N-diphenylaminophenyl)-1,3,4,-oxadiazole (7-OXD-Ph). It was found that the length of an alkyl tail and the structure of an amine strongly affect the phase structure of the oxadiazole derivatives; 3-OXD-Me showed a crystalline phase, 7-OXD-Me showed a liquid-crystal line (LC; nematic) phase and 7-OXD-Ph exhibited a glassy amorphous state. All the compounds emitted strong blue fluorescence: the maximum wavelengths of emission were 420-436nm with high quantum yields (0.81-0.91). Furthermore, polarized photoluminescence was observed in 7-OXD-Me in a nematic phase, and the order parameter estimated by the polarized emission was 0.18. These compounds, therefore, are potential multifunctional materials for photo- and electio-active devices.

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  • Photoinduced change in birefringence and optical switching at near-infrared region based on photochemical phase transition of azobenzene liquid crystals Reviewed

    H Kurihara, A Shishido, T Ikeda, O Tsutsumi, T Shiono

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   441   173 - 184   2005

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    Optical switching of a 1.55-mu m laser beam was explored by means of photochemical phase transition of polymer and low-molecular-weight azobenzene liquid crystals (LCs). It was observed that the 1.55-mu m laser beam could be repeatedly switched by turning on and off the actinic light, and a large change in refractive index was induced in the azobenzene LCs at the near infrared region. It was also found that controlling the thickness of LCs could enhance the change in the transmittance of the 1.55-mu m laser.

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  • Photoinduced alignment behavior of poly(alkyl methacrylate)s containing an azobenzene moiety in the side chain Reviewed

    HB Cha, A Shishido, T Ikeda, T Shiono

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   443   201 - 209   2005

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    A series of poly(alkyl methacrylate)s having azobenzene and cyanobiphenyl moieties were synthesized and their optical properties were characterized. The effect of content of the photosensitive unit and the length of alkyl chain of a transparent unit on the photoresponsive alignment behavior was investigated. The azobenzene monomer (photoresponsive unit), the cyanobiphenyl monomer (mesogenic unit), and the alkyl methacrylate monomers with methyl, ethyl, n-butyl, hexyl or lauryl group (transparent unit) were copolymerized to yield transparent polymer films. Upon irradiation of LPL at 488 nm, a uniaxial optical anisotropy was generated due to the molecular alignment. The photoinduced alignment behavior was strongly dependent on the alkyl chain length and the intensity of the actinic light.

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  • Effects of intensity of actinic light and temperature on photochemical phase transition of azobenzene liquid crystals probed by a near-infrared laser beam Reviewed

    H Kurihara, A Shishido, O Tsutsumi, T Shiono, T Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   443   229 - 238   2005

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    The change in transmittance of a 1.55-mu m laser beam was investigated by a photochemical phase transition of an azobenzene liquid-crystalline polymer. Effects of the intensity of actinic light and temperature on the photoresponsive behavior were explored using laser beams at 633 nm and 1.55 mu m. It was found that the intensity of the actinic light or temperature affected on the response, regardless of the wavelength of the probe beam.

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  • Photoresponsive behavior and photochemical phase transition of amphiphilic diblock liquid-crystalline copolymer Reviewed

    HF Yu, T Iyoda, K Okano, A Shishido, T Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   443   191 - 199   2005

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    The photoresponsive behavior of an amphiphilic diblock liquid-crystalline (LC) copolymer (P40A37) was studied in both toluene solution and spin-coated film. The LC copolymer in a film state showed slower response and relaxation than that in the solution. Significant H-aggregation in the film led to a blue shift by 16 nm at the maximum absorption. The photochemical phase transition was observed with a polarizing optical microscope (POM) upon exposure to 366-nm light. The photoinduced isotropic state remained stable at room temperature, indicating the potential application for 2-D and 3-D storage.

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  • Ethene-norbornene copolymer with high norbornene content produced by ansa-fluorenylamidodimethyltitanium complex using a suitable activator Reviewed

    T Hasan, T Ikeda, T Shiono

    MACROMOLECULES   37 ( 23 )   8503 - 8509   2004.11

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    Ethene-norbornene (E-N) copolymerizations were carried out by (t-BuNSiMe(2)FIu)TiMe2 (1) and (t-BuNSiMe2C5Me4)TiMe2 (2) activated with methylaluminoxane (free from Me3Al) under an atmospheric pressure of ethene at 40 degreesC. 1 showed higher activity than 2. The activity of 1 increased with increasing the feed ratio of norbornene/ethene, but the opposite trend was observed for 2. In the same feed ratio (N/E = 8), the incorporation of norbornene was higher with 1 (N = 50 mol %) than with 2 (N = 38 mol %). The C-13 NMR spectrum of the E-N copolymer obtained with 1 was completely different from that with 2. The former showed the resonances of norbornene dyad and triad, whereas the latter showed only those of alternating and isolated norbornene structures. Some new signals were assigned to the rac,rac-NNN triad. The effects of activators and polymerization temperature were investigated with 1 in more detail, and the 1-Ph3CB(C6F5)(4)/Oct(3)Al system was found to show the highest activity at 80 degreesC and gave the E-N copolymer with the highest N content of 82 mol % and the glass transition temperature 237 degreesC.

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  • Dynamic holographic polymer dispersed liquid crystals. Reviewed

    AM Urbas, J Klosterman, Tondiglia, V, LV Natarajan, RL Sutherland, N Tabirian, T Ikeda, TJ Bunning

    TUNING THE OPTICAL RESPONSE OF PHOTONIC BANDGAP STRUCTURES   5511   18 - 25   2004

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    Controlling the optical properties of patterned optical materials is generally useful. Much headway has been made into patterning passive optical structures and fabricating them of a variety of materials. Recent efforts have been made to tune the properties thermally, electronically and optically. Liquid crystals offer several mechanisms for varying their optical properties. They have been incorporated into patterned templates to make electro-optic and photo-optic materials. Holographic photopolymerization provides a means to form an arbitrary structure incorporating multiple material phases such as liquid crystals. Electro optic holographic polymer dispersed liquid crystals (HPDLCs) have been the subject of extensive investigation. We report photo-optic HPDLCs incorporating azobenzene derived liquid crystals (Azo-LCs).

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  • Large optical torque enhancement by oligothiophene dye in a nematic liquid crystal host Reviewed

    T. Kosa, P. Palffy-Muhoray, H. Zhang, T. Ikeda

    Molecular Crystals and Liquid Crystals   421   107 - 115   2004

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    We have studied the nonlinear optical response of the nematic liquid crystal E7 doped with the oligothiophene dye TR5. Z-scan measurements showed a large positive (self-focusing) nonlinearity, originating in director reorientation. The oligothiophene dye enhances the nonlinearity of the host, in a similar manner to that of azo- and anthraquinone dyes in guest-host systems which exhibit the Janossy effect. The enhancement factor is unusually large
    our TR5-E7 system showed as large a dye-induced optical torque enhancement factor as any observed in a guest-host system. Here we present our experimental results, determine the enhancement factor, and hypothesize that the dominant mechanism involves a photo-induced decrease in the orientational mobility of the dye molecules.

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  • Effect of electrolytes on driving voltages of electroluminescent devices using liquid-crystalline matrices Reviewed

    H Mochizuki, M Kawamoto, T Ikeda

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   42 ( 12 )   7366 - 7367   2003.12

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    In order to lower the operating voltage of molecularly doped electroluminescent (EL) devices using a low-molecular-weight liquid crystal (LC), we added a small amount of electrolytes (tetrabutylammonium bromide: TBAB) to the EL devices. The addition of TBAB decreased the driving voltages by one order of magnitude. Furthermore, the EL devices containing TBAB could be operated under not only a dc mode but also an ac mode.

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  • Additive effect of triphenylphosphine on the living polymerization of 1,3-butadiene with a cobalt dichloride-methylaluminoxane catalytic system Reviewed

    DCD Nath, T Shiono, T Ikeda

    MACROMOLECULAR CHEMISTRY AND PHYSICS   204 ( 16 )   2017 - 2022   2003.11

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    The additive effect of triphenylphosphine (Ph3P) was investigated in 1,3-butadiene polymerization with cobalt dichloride (COCl2) activated by methylaluminoxane (MAO); the catalytic system resulted in slowly-initiated living polymerization with a high cis-1,4 content (about 99%) at 0degreesC. The polymerization behavior, such as the relationship of polymer yield and number-average molecular weight ((M) over bar (n)) with polymerization time, was dependent on the amount of Ph3P added. In the presence of a small amount of Ph3P (Ph3P/Co = 0.025), the kinetic behavior qualitatively resembled that observed in the absence of Ph3P, which indicated that the catalytic system conducted slowly-initiated living polymerization. An increase in the amount of Ph3P (Ph3P/Co > 0.025), however, caused chain transfer reaction. The H-1 NMR analysis of the produced polymers showed that Ph3P changed the microtacticity from 99% of cis-1,4 to 88% of 1,2-unit, depending on the amount of Ph3P added. At the maximum amount of Ph3P (Ph3P/Co = 0.025) necessary for maintaining the livingness of the propagating species. 14% of the 1,2-inserted unit was incorporated at the expense of the cis-1,4-inserted unit. The addition of Ph3P (Ph3P/Co = 0.025) during the polymerization did not affect the livingness and gave a regio-block copolymer of 1,3-butadiene.

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  • Emission behavior of molecularly doped electroluminescent devices using liquid-crystalline matrices Reviewed

    H Mochizuki, T Kubota, M Kawamoto, T Ikeda

    THIN SOLID FILMS   438   294 - 300   2003.8

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    Electroluminescent (EL) behavior has been evaluated in a cell that contained molecular dispersion of 1,4-bis(N,N-diphenylaminophenyl-1,3,4-oxadiazolyl)benzene (OXD) in various liquid crystals (LC); 4-hexyloxy-4'-cyanobiphenyl, 4-octyloxy-4'-cyanobiphenyl (80CB) as low molecular-weight LCs and poly(8-(4-cyano-4'-biphenyl)-1-octanoylacrylate), poly (11-(4-cyano-4'-biphenyl)-1-undecanoylacrylate) as polymer LCs. Among the guest/host mixtures examined, the OXD/8OCB mixture showed the most stable LC phase even at the fraction of OXD up to 30 wt.%. EL emission was observed above the temperature where the OXD/8OCB mixture showed an LC phase. Furthermore, an EL device was fabricated that consisted of interdigital electrodes coated onto a glass substrate. It was found that the EL emission from the device was highly polarized. (C) 2003 Elsevier Science B.V. All rights reserved.

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  • Side-chain polymer liquid crystals containing oxadiazole and amine moieties with carrier-transporting abilities for single-layer light-emitting diodes Reviewed

    M Kawamoto, H Mochizuki, A Shishido, O Tsutsumi, T Ikeda, B Lee, Y Shirota

    JOURNAL OF PHYSICAL CHEMISTRY B   107 ( 21 )   4887 - 4893   2003.5

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    Electrochemical and electroluminescent (EL) properties of a polymer liquid crystal (PLC) composed of an oxadiazole moiety as an electron-transporting unit and an amine moiety as a hole-transporting unit in the same side chain were investigated. It has been found that the polymer is a good candidate for a single-layer light-emitting diode (LED) because it combines carrier-transporting and emission properties in a single species. A polymer LED was fabricated with a simple configuration of ITO/PLC/MgAg to demonstrate EL behavior. The device showed the EL emission in a blue region with a maximum brightness of 13 cd/m(2) at 26 V. Furthermore, a polarized EL emission was observed due to self-assemblies of mesogenic chromophores. The dichroic ratio of the absorption of the polymer film determined by polarized absorption spectra measured with the polarized beam parallel and perpendicular to the rubbing direction was 1.8, and the dichroic ratio of the emission was estimated to be 1.6. These results clearly indicate that the origin of the polarized emission from the polymer film is the anisotropic arrangement of the mesogenic chromophores.

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  • Polymerization of 1,3-butadiene by cobalt dichloride activated with various methylaluminoxanes Reviewed

    DCD Nath, T Shiono, T Ikeda

    APPLIED CATALYSIS A-GENERAL   238 ( 2 )   193 - 199   2003.1

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    1,3-Butadiene polymerization was conducted at 0degreesC with cobalt dichloride (CoCl2) activated by different cocatalysts: MAO (methylaluminoxane), dried-MAO (substantially free of trimethylaluminum), MMAO (triisobutylaluminum-modified methylaluminoxane), dried-MMAO (substantially free of trialkylaluminum) and TMA (trimethylaluminum). MAO and MMAO were effective cocatalysts for 1,3-butadiene polymerization. CoCl2 activated with MAO showed slowly-initiated living polymerization which has been reported previously, whereas, that with MMAO showed deactivation. Neither dried-MAO nor dried-MMAO, TMA activated the catalyst, whereas dried-MAO-TMA (mixtures of dried-MAO and TMA) and dried-MMAO-TMA (mixtures of dried-MMAO and TMA) allowed the polymerization. These results indicated that trialkylaluminums were necessary with MAOs for generating the active species. Dried-MAO-TMA caused frequent chain transfer reactions, whereas dried-MMAO-TMA showed the living like polymerization not only with slow initiation but with slow propagation also, suggesting that the nature of the active species was strongly dependent on the structure of alkylaluminums and MAOs. The microstructure of the resulting polymers analyzed by H-1 and C-13 NMR was cis-1,4 (98-97%); the percentage slightly decreased in the following order: MAO > dried-MAO > MMAO > dried-MMAO, accompanied by the increase of trans-1,4 and 1,2-inserted units. (C) 2002 Elsevier Science B.V. All rights reserved.

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  • Highly efficient formation of holographic gratings in polymer liquid crystals

    K Okano, A Shishido, O Tsutsumi, T Shiono, T Ikeda

    LIQUID CRYSTALS VII   5213   139 - 146   2003

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    We studied the formation of gratings by means of the photoinduced alignment change of polymer liquid crystals (PLCs) in a glassy state. To obtain high diffraction efficiency (eta), we prepared a novel PLC containing an azobenzene group directly connected with a tolane moiety (3AT) which has large birefringence (Deltan). It was found that the value of birefringence in 3AT was extremely high (Deltan = 0.39). When two s-polarized writing beams (Ar+ laser, 488 nm) were interfered on the surface of the 3AT film in the glassy state, multiple diffraction beams were observed immediately, resulting from the grating formation. We explored the effect of light intensity on the grating formation and the relation between the alignment change and eta. The value of eta showed a maximum when the change in photoinduced alignment was almost completed. Furthermore the value of eta was relatively high (eta = 20%) even though the alignment change of mesogens was small.

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  • Highly Efficient Holographic Materials Based on Polymer Liquid Crystals.

    Kunihiko Okano, Atsushi Shishido, Osamu Tsutsumi, Takeshi Shiono, Tomiki Ikeda

    J. Nonlinear Opt. Phys. Mater.   12   539-546   2003

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  • Photoresponsive behavior of azobenzene liquid-crystalline gels Reviewed

    Makoto Nakano, Yanlei Yu, Atsushi Shishido, Osamu Tsutsumi, Akihiko Kanazawa, Takeshi Shiono, Tomiki Ikeda

    Molecular Crystals and Liquid Crystals   398   1 - 9   2003

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    The azobenzene liquid-crystalline gel (LCG) films with macroscopic uniaxial alignment were prepared to investigate photoresponsive behavior. By polarizing microscopy, fiber-like structures aligned in one direction were observed. Furthermore, with a confocal laser scanning microscope (CLSM), it was confirmed that the fiber-like structures were formed even in the bulk of the LCGs. When the LCG films were irradiated with UV light below Tg, changes in the microscopic surface morphology were observed, while no appreciable macroscopic change was observed. On the other hand, when the LCGs were plasticized by suspending in solvents or heating above Tg, the LCG films showed macroscopic changes (e.g. bending) upon UV light irradiation. The bending and unbending could be repeated just by changing the wavelength of the irradiation light. It was suggested that the bending is induced by an absorption gradient which produces a volume difference between the front surface area and the bulk of the gel films.

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  • Supporting effects of methylaluminoxane on propene polymerization with an alkyltitanium complex Reviewed

    H Hagimoto, T Shiono, T Ikeda

    SCIENCE AND TECHNOLOGY IN CATALYSIS 2002   145   129 - 132   2003

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    Solid activators (S-MMAOs) were prepared by supporting dried modified methylaluminoxane (dried MMAO) on silica, alumina and magnesia. Propene polymerization was conducted at 0 degreesC by a chelating (diamide)dimethyltitanium complex ([ArN(CH2)(3)NAr]TiMe2, Ar = 2,6-Pr2C6H3) combined with S-MMAOs. These heterogeneous catalytic systems conducted the polymerization without any induction period. The number-average molecular weight (M-n) of the produced polymers increased linearly against the polymerization time accompanied by narrowing molecular weight distribution (M-w/M-n), which were slightly broader than that of the corresponding homogeneous system. Living polymerization of propene proceeded irrespective of the supports for dried MMAO. The propagation rate and the M-w/M-n value depended on S-MMAO employed. Among these catalytic systems, the [ArN(CH2)(3)NAr]TiMe2-dried MMAO/SiO2 system showed the highest propagation rate and the narrowest M-w/M-n value.

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  • Living polymerization of norbornene via vinyl addition with ansa-fluorenylamidodimethyltitanium complex Reviewed

    T Hasan, K Nishii, T Shiono, T Ikeda

    MACROMOLECULES   35 ( 24 )   8933 - 8935   2002.11

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  • Living nature of propene polymerization with ansa-(cyclopentadienylamido)dimethyltitanium derivatives using MAO as cocatalyst

    Future Technologies for Polyolefin and Olefin Polymerization Catalysis= Technology and Education Publishers= Tokyo   280 - 285   2002.4

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  • Photochemical Modulation of Alignment of Liquid Crystals and Photonic Applications.

    Osamu Tsutsumi, Tomiki Ikeda

    Curr. Opin. Solid State Mat. Sci.   6   563-568   2002

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  • Syndiospecific living polymerization of propene with (t-BuNSiMe2Flu)TiMe2 Using MAO as Cocatalyst Reviewed

    Macromolecules   34 ( 10 )   3142 - 3145   2001.4

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  • Electroluminescent behavior of oxadiazole derivatives in liquid-crystalline media Reviewed

    Hiroyuki Mochizuki, Takahiro Hasui, Osamu Tsutsumi, Akihiko Kanazawa, Takeshi Shiono, Tomiki Ikeda, Chihaya Adachi, Yoshio Taniguchi, Yasuhiko Shirota

    Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals   365   129 - 138   2001

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    Electroluminescent (EL) emission has been investigated in a system which consisted of molecular dispersion of 1,4-bis(N,N-diphenylaminophenyl-1,3,4-oxadiazolyl)benzene (OXD) in a liquid crystal, 4-octyloxy-4'-cyanobiphenyl (80CB). EL emission was observed above the temperature where the OXD/80CB mixture exhibited a liquid-crystalline phase. In addition, we fabricated and evaluated emission of an EL device which consisted of interdigital electrodes coated onto a glass plate. © 2001 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint, a member of the Taylor &amp
    Francis Group.

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  • Liquid Crystalline Coumarin Polymers.Ⅱ: Photo-Chemistry of Side-Group Liquid Crystalline Polymers with Coumarin Moieties

    YanQing Tian, Eiichi Akiyama, Yu Nagase, Akihiko Kanazawa, Osamu Tsutsumi, Tomiki Ikeda

    Transactions of the Material Research Society of Japan   25 ( 4 )   1091 - 1094   2000

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  • Novel Class of Ionic Metallomesogens without Organic Ligands: Thermotropic Liquid-Crystalline Behavior of Tetrachlorometalate Salts and Distinct Polymorphic Transition in Smectic A Phases

    Akihiko Kanazawa, Tomiki Ikeda, Yu Nagase

    Chemistry of Materials   12 ( 12 )   3776 - 3782   2000

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  • Photoinduced orientation of azobenzene liquid crystalline side chain homopolymers Reviewed

    J Liu, QJ Zhang, YL Wu, T Ikeda

    ORGANIC PHOTONIC MATERIALS AND DEVICES   3623   224 - 231   1999

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    A simple casting film of Poly(6-[4-(4-cyanophenyl)diazenylphenyl oxy] hexyl methacrylate)(PM6ABCN) was made on an untreated surface of a glass substrate and adopted as a typical sample to study photoinduced orientation of azobenzene liquid crystalline side chain homopolymers. Below Tg and after irradiation of light at 366 nm, 400 nm, and 436 nm, respectively, the sample shows different UV spectra which can give an expedition on the steady state of the photoinduced orientation. Under various conditions photoinduced orientation of PM6ABCN was examined, and results show that the orientation process is not only dependent on the light strength, but also on the temperature and the wavelength of polarized light used. The maximum extent of orientation below Tg can be obtained within 100 s under irradiation of polarized light of 20 mW/cm(2) at 400 nm, and irradiation at 366 nm causes a lower extent of orientation than that by irradiation at 400 nm and 436 nn because relative more cis isomer was produced in the steady state.

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  • Photoinduced alignment of polymer liquid crystals containing azobenzene moieties in the side-chain. 3. Effect of spacer length of the azobenzene units on alignment behavior Reviewed

    Macromolecules   31 ( 14 )   4457 - 4463   1998.4

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  • Copolymerization of poly(propylene) macromonomer with ethylene by (tert-butanamide)dimethyl(tetramethyl-eta(5)-cyclopentadienyl)silanetitanium dichloride methylaluminoxane catalyst Reviewed

    T Shiono, Y Moriki, T Ikeda, K Soga

    MACROMOLECULAR CHEMISTRY AND PHYSICS   198 ( 10 )   3229 - 3237   1997.10

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    The copolymerization of ethylene and a poly(propylene) macromonomer, the number-average polymerization degree (P-n) of which was about 11, was conducted with (tert-butanamide)dimethyl(tetramethyl-eta(5)-cyclopentadienyl)silanetitanium dichloride (CGC-Ti) combined with methylaluminoxane. The rate of ethylene consumption is increased by adding the macromonomer when copolymerization was carried out at 40 degrees C, whereas such rate enhancement could not be observed at 90 degrees C. It was found that the increase of ethylene polymerization rate is accompanied by the incorporation of the macromonomer. Based on differential scanning calorimetry (DSC) and C-13 NMR measurements of the produced polymers, it was proved that the poly(propylene) macromonomer was copolymerized with the present CGC-Ti catalyst and the P-n value of the macromonomer incorporated in the copolymer does not influence the conversion of the macromonomer.

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  • Photochemical Control of Properties of Ferroelectric Liquid Crystals(3)Photochemical Control of Spontaneous Polarization and Electrooptic Effect. Reviewed

    T. Sasaki, T. Ikeda

    J. Phys. Chem.   99   13013   1995

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  • PHOTOCHEMICAL CONTROL OF SWITCHING BEHAVIORS OF FERROELECTRIC POLYMER LIQUID-CRYSTALS - POLY(2-METHYLBUTYL 4'-(10-ACRYLOYLOXYDECYLOXY)BIPHENYL-4-CARBOXYLATE) Reviewed

    T IKEDA, O ZUSHI, T SASAKI, K ICHIMURA, H TAKEZOE, A FUKUDA, KAW SKARP

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   225   67 - &   1993

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    Switching behaviors of ferroelectric polymer liquid crystal (FPLC), poly(2-methylbutyl 4'-(10-acryloyloxydecyloxy)biphenyl-4-carboxylate), were successfully modulated reversibly by photochemical reaction of photochromic guests (azobenzene derivatives) doped in the FPLC. Chiral azobenzene (AB(chi)) possessing the same structure as the host FPLC at the chiral part was found to enhance the transmitted light intensity through a pair of crossed polarizers on the trans to cis photoisomerization, while the other achiral azobenzene derivatives reduced the transmitted light intensity on photoisomerization. This difference in photoresponsiveness has been attributed to the different effect of the trans-cis photoisomerization on the host mesogens, the change in molecular shape for the achiral azobenzenes and the change in dipole moment for AB(chi).

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  • Orientation control and photophysical behaviors in LB films of long-chain derivative of amino acid containing aromatic ring Reviewed

    Hiroo Nakahara, Hideyuki Endo, Kiyoshige Fukuda, Tomiki Ikeda, Masahiko Sisido

    Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals   218 ( 1 )   177 - 182   1992.6

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    Using a long-chain derivative of amino acid containing naphthalene, the arrangement of the chromophore in the LB films has been examined by circular dichroism (CD) together with UV absorption and fluorescence spectroscopies. The monolayer of N-stearoyl-L-lysyl-L-l-naphthylalanine methylester exhibits a transition from expanded to condensed states. For the LB films prepared at the surface pressures below and above the transition, polarized UV spectra suggest different orientations of the chromophore and also the CD spectra vary significantly of types and magnitude of a Cotton effect. These results were reflected in the fluorescence decay curves for the LB films. © 1992, Taylor &amp
    Francis Group, LLC. All rights reserved.

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  • TIME-RESOLVED OBSERVATION OF ISOTHERMAL PHASE-TRANSITION OF LIQUID-CRYSTALS INDUCED BY PHOTOISOMERIZATION OF AZOBENZENE DOPANT Reviewed

    S KURIHARA, T IKEDA, T SASAKI, HB KIM, S TAZUKE

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   195   251 - 263   1991

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  • PERSISTENCE OF ORDERING IN 4-NORMAL-PENTYL-4'-CYANOBIPHENYL ABOVE THE NEMATIC ISOTROPIC TRANSITION AS DETECTED BY PICOSECOND TIME-RESOLVED FLUORESCENCE SPECTROSCOPY Reviewed

    T IKEDA, S KURIHARA, S TAZUKE

    LIQUID CRYSTALS   7 ( 5 )   749 - 752   1990.5

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  • EFFECT OF STRUCTURE OF PHOTORESPONSIVE MOLECULES ON PHOTOCHEMICAL PHASE-TRANSITION OF LIQUID-CRYSTALS .4. PHOTOCHEMICAL PHASE-TRANSITION BEHAVIORS OF PHOTOCHROMIC AZOBENZENE GUEST POLYMER LIQUID-CRYSTAL HOST MIXTURES Reviewed

    T IKEDA, T MIYAMOTO, S KURIHARA, S TAZUKE

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   188   223 - 233   1990

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  • PHOTOCHEMICALLY INDUCED ISOTHERMAL PHASE-TRANSITION IN LIQUID-CRYSTALS - EFFECT OF INTERACTION OF PHOTORESPONSIVE MOLECULES WITH MATRIX MESOGENS Reviewed

    S KURIHARA, T IKEDA, S TAZUKE

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   178   117 - 132   1990

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  • EFFECT OF STRUCTURE OF PHOTORESPONSIVE MOLECULES ON PHOTOCHEMICAL PHASE-TRANSITION OF LIQUID-CRYSTALS .3. PHOTOCHEMICAL PHASE-TRANSITION BEHAVIORS OF PHOTOCHROMIC AZOBENZENE GUEST ESTER HOST MIXTURES Reviewed

    T IKEDA, T MIYAMOTO, S KURIHARA, S TAZUKE

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   188   207 - 222   1990

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  • Interaction of polymeric drugs with biomembranes Reviewed

    T. Ikeda, S. Tazuke

    Membrane   7 ( 4 )   203 - 213   1982

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    DOI: 10.5360/membrane.7.203

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Books

  • 液晶を操る光化学 光化学協会編「光化学の驚異」第5章

    講談社ブルーバックス  2006 

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  • Nano Intelligent Liquid-Crystalline Materials

    Maruzen  2005 

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  • 高分子液晶 国武豊喜監修「ナノマテリアルハンドブック」

    エヌ・ティー・エス  2005 

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  • ナノインテリジェント(液晶)材料 日本化学会編第5版実験化学講座28「ナノテクノロジーの化学」3デバイス・応用「新機能ナノ材料」

    丸善  2005 

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  • Liquid-Crystalline Polymers

    NTS  2005 

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  • フォトクロミズムを利用する光応答性高分子液晶材料

    エヌ・ティー・エス  2004 

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  • 高分子アゾベンゼン液晶のフォトニクス-ホログラムと光アクチュエータへの応用

    エヌ・ティー・エス  2004 

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  • アゾベンゼン液晶ゲルアクチュエーター

    エヌ・ティー・エス  2004 

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  • Liquid Crystal Photonics: Opto-Photochemical Effects in Photoresponsive Liquid Crystals

    Wiley-VCH  2001 

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  • Liquid Crystal Photonics: Opto-Photochemical Effects in Photoresponsive Liquid Crystals

    Wiley-VCH  2001 

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MISC

  • Photomobile polymer materials: Towards light-driven plastic motors

    Munenori Yamada, Mizuho Kondo, Jun-ichi Mamiya, Yanlei Yu, Motoi Kinoshita, Christopher J. Barrett, Tomiki Ikeda

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   47 ( 27 )   4986 - 4988   2008

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    DOI: 10.1002/anie.200800760

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  • Photomechanics of liquid-crystalline elastomers and other polymers

    Tomiki Ikeda, Jun-ichi Mamiya, Yanlei Yu

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   46 ( 4 )   506 - 528   2007

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    DOI: 10.1002/anie.200602372

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  • Photomodulation of liquid crystal orientations for photonic applications

    Tomiki Ikeda

    Journal of Materials Chemistry   13 ( 9 )   2037 - 2057   2003.9

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    Two types of photomodulation of orientations of liquid crystals (LCs) are reviewed: 1) order-disorder phase transitions of LCs induced by photochemical reactions of photochromic molecules and 2) order-order alignment change of LCs (change in LC directors) induced by photochemical reactions or without photochemical events. Both processes produce a large refractive-index modulation, which forms the basis of a range of photonic applications. Various modes of photomodulation of orientations of LCs with plausible mechanisms and their possible applications in photonics are described.

    DOI: 10.1039/b306216n

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  • Anisotropic bending and unbending behavior of azobenzene liquid-crystalline gels by light exposure

    T Ikeda, M Nakano, YL Yu, O Tsutsumi, A Kanazawa

    ADVANCED MATERIALS   15 ( 3 )   201 - +   2003.2

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    Freestanding azobenzene-containing liquid-crystalline gel films that undergo a significant and anisotropic bending toward the irradiation direction when exposed to UV light have been prepared. When the bent films are exposed to visible light they unbend immediately, and the initial flat films are restored (see Figure and Inside front cover).

    DOI: 10.1002/adma.200390045

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  • Photomodulation of liquid crystal orientations for photonic applications

    T Ikeda

    JOURNAL OF MATERIALS CHEMISTRY   13 ( 9 )   2037 - 2057   2003

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    Two types of photomodulation of orientations of liquid crystals (LCs) are reviewed: 1) order-disorder phase transitions of LCs induced by photochemical reactions of photochromic molecules and 2) order-order alignment change of LCs (change in LC directors) induced by photochemical reactions or without photochemical events. Both processes produce a large refractive-index modulation, which forms the basis of a range of photonic applications. Various modes of photomodulation of orientations of LCs with plausible mechanisms and their possible applications in photonics are described.

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  • Photomechanics: directed bending of a polymer film by light. International journal

    Yanlei Yu, Makoto Nakano, Tomiki Ikeda

    Nature   425 ( 6954 )   145 - 145   2003

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    Polymer solutions and solids that contain light-sensitive molecules can undergo photo-contraction, whereby light energy is converted into mechanical energy. Here we show that a single film of a liquid-crystal network containing an azobenzene chromophore can be repeatedly and precisely bent along any chosen direction by using linearly polarized light. This striking photomechanical effect results from a photoselective volume contraction and may be useful in the development of high-speed actuators for microscale or nanoscale applications, for example in microrobots in medicine or optical microtweezers.

    DOI: 10.1038/425145a

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  • OPTICAL SWITCHING AND IMAGE STORAGE BY MEANS OF AZOBENZENE LIQUID-CRYSTAL FILMS

    T IKEDA, O TSUTSUMI

    SCIENCE   268 ( 5219 )   1873 - 1875   1995.6

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    Liquid crystals are promising materials for optical switching and image storage because of their high resolution and sensitivity. Azobenzene liquid crystals (LCs) have been developed, in which azobenzene moieties play roles as both mesogens and photosensitive chromophores. Azobenzene LC films showed a nematic phase in trans isomers and no LC phase in cis isomers. Trans-cis photoisomerization of azobenzene with a laser pulse resulted in a nematic-to-isotropic phase transition with a rapid optical response of 200 microseconds.

    DOI: 10.1126/science.268.5219.1873

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  • Optical switching and image storage by means of azobenzene liquid-crystal films

    Tomiki Ikeda, Osamu Tsutsumi

    Science   268 ( 5219 )   1873 - 1875   1995

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    Liquid crystals are promising materials for optical switching and image storage because of their high resolution and sensitivity. Azobenzene liquid crystals (LCs) have been developed, in which azobenzene moieties play roles as both mesogens and photosensitive chromophores. Azobenzene LC films showed a nematic phase in trans isomers and no LC phase in cis isomers. Trans-cis photoisomerization of azobenzene with a laser pulse resulted in a nematic-to-isotropic phase transition with a rapid optical response of 200 microseconds.

    DOI: 10.1126/science.268.5219.1873

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  • PHOTOCHEMICAL SWITCHING OF POLARIZATION IN FERROELECTRIC LIQUID-CRYSTAL FILMS

    T IKEDA, T SASAKI, K ICHIMURA

    NATURE   361 ( 6411 )   428 - 430   1993.2

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    LIQUID crystals have been used extensively as active media in display devices such as full-colour television screens. These devices are generally based on changes in the arrangement of the liquid-crystal molecules induced by electric fields, which change their optical properties1. Ferroelectric liquid crystals2,3 exhibit spontaneous polarization and therefore show a faster response to changes in the applied field. Switching of this field causes a reversal in the direction of polarization2-5. Here we report polarization switching in ferroelectric liquid crystals driven by a photochemical process. The liquid-crystal films are doped with a photochromic compound which undergoes trans-cis isomerization on irradiation. Photoisomerization induces a change in the switching potential of the host liquid-crystal film, and thereby causes switching at the irradiated sites. The process is fast, stable, reversible and repeatable, and should be exploitable in device applications.

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  • Photochemical switching of polarization in ferroelectric liquid-crystal films

    Tomiki Ikeda, Takeo Sasaki, Kunihiro Ichimura

    Nature   361 ( 6411 )   428 - 430   1993

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    LIQUID crystals have been used extensively as active media in display devices such as full-colour television screens. These devices are generally based on changes in the arrangement of the liquidcrystal molecules induced by electric fields, which change their optical properties1. Ferroelectric liquid crystals2,3 exhibit spontaneous polarization and therefore show a faster response to changes in the applied field. Switching of this field causes a reversal in the direction of polarization2-
    5. Here we report polarization switching in ferroelectric liquid crystals driven by a photochemical process. The liquid-crystal films are doped with a photochromic compound which undergoes trans-cis isomerization on irradiation. Photoisomerization induces a change in the switching potential of the host liquid-crystal film, and thereby causes switching at the irradiated sites. The process is fast, stable, reversible and repeatable, and should be exploitable in device applications. © 1993 Nature Publishing Group.

    DOI: 10.1038/361428a0

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  • Two-photon actuation of crosslinked liquid-crystalline polymers utilizing energy transfer system

    Shota Sasaki, Toru Ube, Kenji Katayama, Masayasu Muramatsu, Hiroshi Miyasaka, Tomiki Ikeda

    Molecular Crystals and Liquid Crystals   662 ( 1 )   53 - 60   2018.2

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    © 2018 Taylor & Francis Group, LLC. We prepared crosslinked azotolane liquid-crystalline polymer (LCP) films doped with a stilbene derivative (two-photon chromophore) utilizing an interpenetrating polymer network (IPN) structure. The IPN films bend toward the light source upon irradiation with femtosecond laser pulses at 600 nm, which can excite the stilbene derivative by two-photon absorption. The bending speed of the IPN films increases with the square of the laser pulse intensity, which is compelling evidence for the two-photon processes.

    DOI: 10.1080/15421406.2018.1466241

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  • Foreword

    Lee-Soon Park, Yanlei Yu, Jianhua Zhang, Tomiki Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   644 ( 1 )   2017

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    DOI: 10.1080/15421406.2016.1275724

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  • 20th International Symposium on Advanced Display Materials and Devices (ADMD2016) Foreword

    Jianhua Zhang, Tomiki Ikeda, Lee-Soon Park, Yanlei Yu

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   651 ( 1 )   1 - 1   2017

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    DOI: 10.1080/15421406.2017.1338462

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  • Foreword

    Tomiki Ikeda, Lee-Soon Park, Yanlei Yu, Kiyoshi Kanie

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   617 ( 1 )   1 - 1   2015.8

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    DOI: 10.1080/15421406.2015.1071981

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  • Special Issue: 7th Italian-Japanese Workshop on Liquid Crystals and 10th National Meeting of the Italian Liquid Crystal Society Foreword

    Antonio d'Alessandro, Tomiki Ikeda, Paolo Pasini, Claudio Zannoni

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   614 ( 1 )   1 - 1   2015.6

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    DOI: 10.1080/15421406.2015.1063923

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  • MATERIALS SCIENCE A superelastic organic crystal

    Tomiki Ikeda, Toru Ube

    NATURE   511 ( 7509 )   300 - 301   2014.7

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    DOI: 10.1038/511300a

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  • Fabrication of photomobile polymer materials with a bilayer structure and their photoresponsive behavior

    Tomiki Ikeda

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   245   2013.4

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  • Photocontrollable Liquid-Crystalline Actuators

    Haifeng Yu, Tomiki Ikeda

    ADVANCED MATERIALS   23 ( 19 )   2149 - 2180   2011.5

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    DOI: 10.1002/adma.201100131

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  • Photomobile Polymer Materials : Amplification of Changes at a Molecular Level to Macroscopic Deformation

    NAKA Yumiko, IKEDA Tomiki

    Photochemistry   41 ( 1 )   3 - 9   2010.4

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  • Photoinduced Reorientation of Dye-Doped Liquid Crystals and Its Application to Microoptical Elements for Self-Emitting Devices Reviewed

    Motoi Kinoshita, Tomohiro Kobayashi, Keisuke Takano, Yunmi Nam, Tomiki Ikeda

    LIQUID CRYSTALS XIV   7775   2010

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    Shortcoming of a planar self-emitting device is only a small fraction of light generated in the device available due to a total internal reflection at the air/substrate interface. To increase a luminance efficiency of the device, microlens arrays are most useful: they extract the total internal reflection of light at the air/substrate interface. In this study, we investigated photoinduced reorientation behavior of dye-doped polymerizable liquid crystals to fabricate a novel planar microlens array film as an optical component for a self-emitting device.

    DOI: 10.1117/12.859779

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  • Photomobile polymer materials

    Function & materials   29 ( 10 )   43 - 49   2009.10

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  • Nano self-assembled photochromic liquid-crystalline polymers

    60 ( 6 )   419 - 424   2009.6

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  • Photomobile polymer materials

    Jun-Ichi Mamiya, Munenori Yamada, Yumiko Naka, Mizuho Kondo, Tomiki Ikeda

    Kobunshi Ronbunshu   66 ( 3 )   79 - 87   2009.3

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    An actuator is an energy transducer that can convert a variety of input energies to mechanical quantities such as displacement, strain, velocity and stress. Up to now, many types of materials have been developed as actuator materials. Polymer materials driven by light could play an important role as an efficient energy conversion system because light is an energy source that can be controlled remotely, instantly and precisely. Liquid-crystalline elastomers (LCEs) are superior soft materials that possess both LC orders and elasticity due to polymer networks. A large deformation can be generated in LCEs, such as reversible contraction and expansion, and even bending, by incorporating photochromic molecules, such as an azobenzene, with the aid of photochemical reactions of these chromophores. We summarize the recent progress of polymer materials that can convert light energy into mechanical work directly (photomechanical effect), especially photomobile polymers that show movements in all dimensions controlled by light. © 2009, The Society of Polymer Science, Japan.

    DOI: 10.1295/koron.66.79

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  • Photomobile polymer materials

    Jun-Ichi Mamiya, Munenori Yamada, Yumiko Naka, Mizuho Kondo, Tomiki Ikeda

    Kobunshi Ronbunshu   66 ( 3 )   79 - 87   2009.3

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    An actuator is an energy transducer that can convert a variety of input energies to mechanical quantities such as displacement, strain, velocity and stress. Up to now, many types of materials have been developed as actuator materials. Polymer materials driven by light could play an important role as an efficient energy conversion system because light is an energy source that can be controlled remotely, instantly and precisely. Liquid-crystalline elastomers (LCEs) are superior soft materials that possess both LC orders and elasticity due to polymer networks. A large deformation can be generated in LCEs, such as reversible contraction and expansion, and even bending, by incorporating photochromic molecules, such as an azobenzene, with the aid of photochemical reactions of these chromophores. We summarize the recent progress of polymer materials that can convert light energy into mechanical work directly (photomechanical effect), especially photomobile polymers that show movements in all dimensions controlled by light. © 2009, The Society of Polymer Science, Japan.

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  • Rewritable Bragg Holograms of Azobenzene Polymers with Fast Response Reviewed

    Shishido Atsushi, Cha Hyo-Bok, Ikeda Tomiki

    LIQUID CRYSTALS XIII   7414   2009

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    Amorphous copolymers were synthesized with azobenzene methacrylate, cyanobiphenyl methacrylate, and alkyl methacrylate, in which the azobenzene acts as a photoresponsive part to undergo photoisomerization, the cyanobiphenyl is involved in a change in refractive index triggered by the photoisomerization of the azobenzene, and the alkyl methacrylate is to prevent light scattering, respectively. The obtained polymers showed no LC phase in spite of the incorporation of the common mesogenic group. When two writing beams were interfered in the thick polymer films, the diffraction of the probe beam was observed. The first-order diffraction efficiency reached more than 70 % within 500 ms. On the other hand, the intensity of the zeroth-order beam decreased in proportion to the increase in that of the first-order diffracted beam. It is clear that the intensity of the zeroth-order beam is transferred to that of the first-order diffraction with no optical loss due to the formation of the Bragg gratings. When the writing beams were turned off, the diffraction efficiency remained unchanged. When the recorded grating was kept in the dark at room temperature, sufficient diffraction efficiency was generally retained after a year. However, the grating was easily erased when heated up above T-g for several seconds, and rewritability was confirmed more than 100 cycles. No shrinkage was observed through those processes.

    DOI: 10.1117/12.828029

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  • Photoresponsive Behavior of Azotolane Liquid Crystals

    Kunihiko Okano, Tomiki Ikeda

    Proceeding of SPIE   7232   723209 - 1   2009

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    In this study, we irradiated homogeneously aligned films of an azotolane liquid-crystalline polymer with a single femtosecond (fs) laser pulse. Upon irradiation of the single pulse, the change in Delta n was induced by destruction of due to destroy the homogeneous alignment of the azotolane moieties was induced. The estimated value of the change in Delta n was >0.2, and the response time was about 400 ns. When the experiment temperature was below glass transition temperature, the change in alignment induced by the pulsed irradiation was preserved without a thermal relaxation. On the other hand, the changed alignment completely recovered to the initial state with an increase in temperature.

    DOI: 10.1117/12.804146

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  • Highly Birefringent Liquid-Crystalline Polymers for Efficient Light Modulation

    OKANO Kunihiko, IKEDA Tomiki

    Journal of the Japanese Liquid Crystal Society   12 ( 4 )   269 - 278   2008.10

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  • Preface

    Yue Zhao, Tomiki Ikeda

    Smart Light-Responsive Materials: Azobenzene-Containing Polymers and Liquid Crystals   xiii - xv   2008.8

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    DOI: 10.1002/9780470439098

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  • Light-Driven Soft Actuator Materials Based on Liquid-Crystalline Polymers Reviewed

    Yanlei Yu, Ruoyuan Yin, Jixiang Xu, Futao Cheng, Mizuho Kondo, Tomiki Ikeda

    LIQUID CRYSTAL XII   7050   2008

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    Various kinds of crosslinked liquid-crystal line polymers were synthesized with acrylate monomers and diacrylate cross-linkers containing azobenzene moieties. The effect of spacer length on photoinduced bending behavior of the polymer films was investigated. The films with long spacers exhibited low glass transition temperatures and underwent bending and unbending behavior at room temperature. Mechanical force generated during the process of UV light irradiation was also measured. It was found that the maximum force increased with the increment of the cross-linking density and the intensity of UV light.

    DOI: 10.1117/12.794183

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  • Is chemical crosslinking necessary for the photoinduced bending of polymer films?

    Jun-ichi Mamiya, Akira Yoshitake, Mizuho Kondo, Yanlei Yu, Tomiki Ikeda

    JOURNAL OF MATERIALS CHEMISTRY   18 ( 1 )   63 - 65   2008

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    Freestanding crosslinked liquid-crystalline polymer films obtained by self-assembly through intermolecular hydrogen bonding showed photoinduced bending and unbending. The structural change at the microscopic level, caused by trans-cis photoisomerization of the azobenzene moieties at the hydrogen-bonded crosslinks, is successfully converted into a macroscopic deformation in the liquid-crystalline polymer films.

    DOI: 10.1039/b715855f

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  • Photoresponsive Liquid Crystals

    IKEDA Tomiki

    Journal of the Japanese Liquid Crystal Society   11 ( 3 )   207 - 214   2007.7

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  • Formation of Bragg gratings with large angular multiplicity by means of the photoinduced reorientation of azobenzene copolymers

    Aya Saishoji, Daisuke Sato, Atsushi Shishido, Tomiki Ikeda

    LANGMUIR   23 ( 1 )   320 - 326   2007.1

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    Optically transparent thick films of methacrylate copolymer containing donor-acceptor-type azobenzene and cyanobiphenyl moieties were prepared, and their optical properties were explored in terms of a photoinduced change in molecular alignment and the formation of Bragg gratings with angular and polarization multiplicity. Azobenzene moieties substituted with ethoxy, cyano, and nitro groups were employed, and their photoresponsive behavior was investigated. It was found by polarized UV-vis spectroscopy that the alignment of azobenzene moieties in the films was random in the initial state but became perpendicular to the direction of polarization of the writing beam after irradiation with a linearly polarized beam from an Ar+ laser at 514 nm. The film containing the cyanoazobenzene moieties showed the fastest formation of optical anisotropy due to an efficient change in molecular alignment. When two linearly polarized beams from the Ar+ laser were allowed to interfere in the films with a thickness of 200 mu m, the diffraction beam was observed immediately and reached 97% upon photoirradiation at 200 mW/cm(2) for 5 min. It was clearly observed that the response time became shorter with an increase in the light intensity of the writing beams, maintaining the high diffraction efficiency. Furthermore, it was clearly seen that the diffraction efficiency strongly depended on the direction of polarization of the reading beam. Holographic multiple data storage in a film was demonstrated, and 55 holograms with angular multiplicity were recorded successfully. In addition, multiple data storage using the polarization and angle selectivity simultaneously was first demonstrated.

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  • Formation of Bragg gratings with large angular multiplicity by means of the photoinduced reorientation of azobenzene copolymers

    Aya Saishoji, Daisuke Sato, Atsushi Shishido, Tomiki Ikeda

    LANGMUIR   23 ( 1 )   320 - 326   2007.1

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    Optically transparent thick films of methacrylate copolymer containing donor-acceptor-type azobenzene and cyanobiphenyl moieties were prepared, and their optical properties were explored in terms of a photoinduced change in molecular alignment and the formation of Bragg gratings with angular and polarization multiplicity. Azobenzene moieties substituted with ethoxy, cyano, and nitro groups were employed, and their photoresponsive behavior was investigated. It was found by polarized UV-vis spectroscopy that the alignment of azobenzene moieties in the films was random in the initial state but became perpendicular to the direction of polarization of the writing beam after irradiation with a linearly polarized beam from an Ar+ laser at 514 nm. The film containing the cyanoazobenzene moieties showed the fastest formation of optical anisotropy due to an efficient change in molecular alignment. When two linearly polarized beams from the Ar+ laser were allowed to interfere in the films with a thickness of 200 mu m, the diffraction beam was observed immediately and reached 97% upon photoirradiation at 200 mW/cm(2) for 5 min. It was clearly observed that the response time became shorter with an increase in the light intensity of the writing beams, maintaining the high diffraction efficiency. Furthermore, it was clearly seen that the diffraction efficiency strongly depended on the direction of polarization of the reading beam. Holographic multiple data storage in a film was demonstrated, and 55 holograms with angular multiplicity were recorded successfully. In addition, multiple data storage using the polarization and angle selectivity simultaneously was first demonstrated.

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  • Bragg-type polarization gratings formed in thick polymer films containing azobenzene and tolane moieties

    Makoto Ishiguro, Daisuke Sato, Atsushi Shishido, Tomiki Ikeda

    LANGMUIR   23 ( 1 )   332 - 338   2007.1

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    Holographic gratings were formed in thick polymer films containing azobenzene and diphenylacetylene (tolane) moieties in the Bragg regime. Amorphous polymers containing various contents of the azobenzene moiety with photosensitivity and the tolane moiety with large birefringence in the side chain were synthesized, and optically transparent thick polymer films were prepared. The films were irradiated with a linearly polarized beam from an Ar+ laser (488 nm), and the transmittance of a He-Ne laser beam (633 nm) through a pair of crossed polarizers, with the film between them, was measured to estimate a photoinduced birefringence (Delta n). The value of Delta n increased with an increase in the tolane moiety content in the polymer films. When two linearly polarized beams at 488 nm were interfered in the film, a diffraction beam was observed, and the maximum diffraction efficiency (eta) increased with the tolane moiety content. In the film containing 70 mol% of the tolane moiety, the highest eta of 99% was achieved, and angular selectivity due to Bragg diffraction was clearly observed. We consider the cooperative molecular motion of the tolane moieties to be induced by the photoinduced change in alignment of the azobenzene moieties even if the polymers show no liquid-crystalline phase. When two orthogonal circularly polarized beams were allowed to interfere in the film, a Bragg-type polarization grating was formed. It was found that the value of eta reached 90% within 920 ms.

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  • Bragg-type polarization gratings formed in thick polymer films containing azobenzene and tolane moieties

    Makoto Ishiguro, Daisuke Sato, Atsushi Shishido, Tomiki Ikeda

    LANGMUIR   23 ( 1 )   332 - 338   2007.1

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    Holographic gratings were formed in thick polymer films containing azobenzene and diphenylacetylene (tolane) moieties in the Bragg regime. Amorphous polymers containing various contents of the azobenzene moiety with photosensitivity and the tolane moiety with large birefringence in the side chain were synthesized, and optically transparent thick polymer films were prepared. The films were irradiated with a linearly polarized beam from an Ar+ laser (488 nm), and the transmittance of a He-Ne laser beam (633 nm) through a pair of crossed polarizers, with the film between them, was measured to estimate a photoinduced birefringence (Delta n). The value of Delta n increased with an increase in the tolane moiety content in the polymer films. When two linearly polarized beams at 488 nm were interfered in the film, a diffraction beam was observed, and the maximum diffraction efficiency (eta) increased with the tolane moiety content. In the film containing 70 mol% of the tolane moiety, the highest eta of 99% was achieved, and angular selectivity due to Bragg diffraction was clearly observed. We consider the cooperative molecular motion of the tolane moieties to be induced by the photoinduced change in alignment of the azobenzene moieties even if the polymers show no liquid-crystalline phase. When two orthogonal circularly polarized beams were allowed to interfere in the film, a Bragg-type polarization grating was formed. It was found that the value of eta reached 90% within 920 ms.

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  • 偏光制御による光駆動高分子 (特集 偏光の新展開)

    近藤 瑞穂, 池田 富樹

    O plus E   29 ( 1 )   53 - 59   2007.1

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  • Photo-mechanical effects in azobenzene-containing soft materials

    Christopher J. Barrett, Jun-ichi Mamiya, Kevin G. Yager, Tomiki Ikeda

    SOFT MATTER   3 ( 10 )   1249 - 1261   2007

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    The change in shape inducible in some photo-reversible molecules using light can effect powerful changes to a variety of properties of a host material. The most ubiquitous natural molecule for reversible shape change is the rhodopsin-retinal protein system that enables vision, and this is perhaps the quintessential reversible photo-switch. Perhaps the best artificial mimic of this strong photo-switching effect however, for reversibility, speed, and simplicity of incorporation, is azobenzene. This review focuses on the study and application of reversible changes in shape that can be achieved with various systems incorporating azobenzene. This photo-mechanical effect can be defined as the reversible change in shape inducible in some molecules by the adsorption of light, which results in a significant macroscopic mechanical deformation of the host material. Thus, it does not include simple thermal expansion effects, nor does it include reversible but non-mechanical photo- switching or photo-chemistry, nor any of the wide range of optical and electro-optical switching effects for which good reviews exist elsewhere.

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  • 偏光制御による光駆動高分子

    近藤瑞穂, 池田富樹

    O plus E   29   11 - 17   2007

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  • Photomechanical effects of ferroelectric liquid-crystalline elastomers containing azobenzene chromophores

    Yanlei Yu, Taketo Maeda, Jun-ichi Mamiya, Tomiki Ikeda

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   46 ( 6 )   881 - 883   2007

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    DOI: 10.1002/anie.200603053

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  • Azotolane liquid-crystalline polymers: Huge change in birefringence by photoinduced alignment change

    Kunihiko Okano, Osamu Tsutsumi, Atsushi Shishido, Tomiki Ikeda

    Journal of the American Chemical Society   128 ( 48 )   15368 - 15369   2006.12

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    Novel liquid-crystalline polymers (LCPs) containing a long azotolane moiety were synthesized, and the relationship between the chemical structures and the photoresponsive behavior was investigated. All homogeneously aligned LCP films exhibited extremely high values of birefringence (Δn) in the wide wavelength range. Specifically, the azotolane LCP with two azobenzene units showed the most efficient change in the alignment of the azotolane moiety with a huge change in Δn (≥0.65). This means that the high value of Δn in the homogeneously aligned state can be converted to the change in Δn effectively. Copyright © 2006 American Chemical Society.

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  • Macroscopic parallel nanocylinder array fabrication using a simple rubbing technique

    Haifeng Yu, Jingze Li, Tomiki Ikeda, Tomokazu Iyoda

    ADVANCED MATERIALS   18 ( 17 )   2213 - +   2006.9

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    A convenient pathway for controlling defect-free nanoscopic domains large areas is illustrated. A simple rubbing technique is used to align nanocylinders self-assembled in an amphiphilic diblock liquid-crystalline copolymer by introducing novel supramolecular cooperative motions between mesogens and microphase domains. A 3D macroscopic array of the nanocylinders over a large area is achieved parallel to the rubbing direction (see figure and inside cover).

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  • White emission from liquid-crystalline copolymers containing oxadiazole moieties in the side chain

    Masuki Kawamoto, Takuji Tsukamoto, Motoi Kinoshita, Tomiki Ikeda

    APPLIED PHYSICS LETTERS   89 ( 12 )   121920/1-121920/3   2006.9

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    A liquid-crystalline polymer in the side chain was synthesized through copolymerization of a bipolar carrier-transporting monomer with a liquid-crystalline monomer containing oxadiazole moieties substituted with trifluoromethyl groups. A single-layer light-emitting diode of indium tin oxide (ITO)/copolymer/MgAg emitted white light with a maximum luminous efficiency of 0.1 cd/A. The origin of the white emission in the copolymer is the electroplex between bipolar carrier-transporting moieties and strong electron-withdrawing moieties. Furthermore, a simple multilayer device with configuration of ITO/poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid)/copolymer/MgAg device showed white emission with CIE 1931 chromaticity coordinates (x,y): (0.30, 0.33). (c) 2006 American Institute of Physics.

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  • Photoinduced alignment of nanocylinders by supramolecular cooperative motions

    Haifeng Yu, Tomokazu Iyoda, Tomiki Ikeda

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   128 ( 34 )   11010 - 11011   2006.8

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    DOI: 10.1021/ja064148f

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  • One- and two-photon induced phase transition behavior of nematic liquid crystals containing bis-styryl benzene as a photoresponsive chromophore

    Osamu Tsutsumi, Asami Ohashi, Tomiki Ikeda, Seth R. Marder, Joseph W. Perry

    THIN SOLID FILMS   509 ( 1-2 )   118 - 122   2006.6

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    One- and two-photon induced phase transition behavior of low-molecular-weight and polymer liquid crystals (M) was observed. When a photochemical reaction of a two-photon absorbing dye was induced in a nemnatic (N) LC, N-to-isotropic (I) phase transition was induced with high spatial resolution. As a result of the phase transition, the refractive index of the materials was changed by two-photon processes. Furthermore, the I phase induced in the polymer LC was thermally stable and it still appeared after heating above N-I phase transition temperature. The results reported here are the first observation of the photochemical phase transition of the LCs induced by a two-photon process. (c) 2005 Elsevier B.V. All rights reserved.

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  • Emission behavior of electroluminescent device using a liquid crystal and an electrolyte

    H Mochizuki, T Ikeda

    THIN SOLID FILMS   499 ( 1-2 )   147 - 152   2006.3

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    In order to lower the operating voltage of molecularly doped electroluminescent (EL) devices using a low-molecular-weight liquid crystal (LC), we added a small amount of electrolytes (tetrabutylammonium bromide: TBAB) to the EL devices. The addition of TBAB decreased the driving voltages by one order of magnitude. Furthermore, the EL devices containing TBAB could be operated under not only a dc mode but also an ac mode. It has become apparent that the emission intensity increases in the order of smectic A phase < nematic phase=isotropic phase, suggesting that the emission intensity is closely related to the viscosity of the LC phase and mobility of the electrolyte. (c) 2005 Elsevier B.V All rights reserved.

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  • An azotolane liquid-crystalline polymer exhibiting extremely large birefringence and its photoresponsive behavior

    Kunihiko Okano, Atsushi Shishido, Tomiki Ikeda

    Advanced Materials   18 ( 4 )   523 - 527   2006.2

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    Synthesis of a highly birefringent liquid-crystalline polymer (LCP) containing the azotolane functional group in the mesogenic moiety was investigated. The homogeneously aligned film of the LCP film exhibited a large delta in a wide wavelength range. The photoismerization behavior of the azobenzene moiety in the mesogen in P4TA in toleune was investigated. Results show that the LCP film exhibits rewritability with little photobleaching.

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  • Stereospecific polymerization of propylene with group 4 ansa-fluorenylamidodimethyl complexes

    Kei Nishii, Hideaki Hagihara, Tomiki Ikeda, Munetaka Akita, Takeshi Shiono

    Journal of Organometallic Chemistry   691   193 - 201   2006.1

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    Group 4 [η1:η3-tert- butyl(dimethylfluorenylsilyl)amido]dimethyl complexes [t-BuNSiMe2Flu]MMe2(M = Ti, 1; Zr, 2; Hf, 3) were synthesized in a one-pot synthesis starting from the ligand, MeLi and MCl4(M = Ti, Zr, Hf), respectively. The structures of these complexes were determined by X-ray crystallography and the results obtained revealed that the fluorenyl ligand coordinates to center metal in a η3-manner irrespective of center metal employed. Propylene polymerization was conducted at 0 or 20 °C in toluene by 1-3 combined with dried methylaluminoxane (MAO), which was prepared from the toluene solutions of MAO by removing free trialkylaluminiums, and HNMe2PhB(C6F5)4in the presence of triisobutylaluminium. The 1-dried MAO system gave the polymer with syndiotactic triad (rr) of 63% at 0 °C, whereas 2 and 3 did not give any polymer in the same conditions. The 2-dried MAO system gave the polymer with the highest syndiotacticity (rr = 97%) at 20 °C, although the activity was low. The 3-dried MAO system did not give any polymer even at 20 °C. When HNMe2PhB(C6F5)4was used in place of dried MAO at 20 °C, 1 gave almost atactic polymer, while 2 and 3 gave highly syndiotactic one (rr > 90%). These results indicate that the catalytic performance strongly depended on the center metal of the ansa- fluorenylamidodimethyl complexes as well as cocatalysts employed. © 2005 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jorganchem.2005.08.027

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  • Photochemical phase transition behavior of highly birefringent azotolane liquid-crystalline polymer films: Effects of the position of the tolane group and the donor-acceptor substituent in the mesogen

    K Okano, A Shishido, T Ikeda

    MACROMOLECULES   39 ( 1 )   145 - 152   2006.1

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    Highly birefringent liquid-crystalline polymers (LCPs) containing an azobenzene group directly connected to a tolane moiety (azotolane moiety) were synthesized. Attention was focused on the effect of the position of the tolane moiety in the mesogenic azotolane group and the donor-acceptor substituent on photochemical phase transition behavior. In solution, cis-trans back-isomerization of the LCP containing azotolane moieties with a donor-acceptor was faster than that of LCPs having no acceptor groups. All the LCP films showed a homogeneous alignment and very high values of birefringence (about 0.4 at 633 nm). In the LCPs with a conventional azotolane moiety, a large change in birefringence (above 0.35) was induced repeatedly by irradiation of UV light. Furthermore, we investigated photoswitching behavior at telecommunication wavelength (1550 nm) based on the photochemical phase transition by irradiation of UV light.

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  • A Simple Formulation for Rewritable Bragg Holograms with Angle and Polarization Multiplicity

    T. Ikeda, A. Shishido

    Proc. SPIE   6332   63320S/1-63320S/5   2006

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    Holography is one of the most promising techniques that enables ultra-high density optical data storage with a simple and small optical setup. The key component in holographic devices is a holographic material that meets various requirements such as high diffraction efficiency, fast response, and stability. Furthermore, additional problems, rewritability and reversibility, must be solved in rewritable holographic materials which are more convenient. In this paper, we successfully achieved rewritable holograms with 55 multiplicities by a simple formulation of optically transparent copolymer films containing azobenzene and mesogenic moieties. The recorded hologram was stable for more than six months and was rewritable over 300 times. In addition, holograms with angle and polarization multiplicity were recorded by controlling the incident angle and the polarization direction of writing beams independently.

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  • Soft actuators based on liquid-crystalline elastomers

    Yanlei Yu, Tomiki Ikeda

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   45 ( 33 )   5416 - 5418   2006

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    DOI: 10.1002/anie.200601760

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  • How does the initial alignment of mesogens affect the photoinduced bending behavior of liquid-crystalline elastomers?

    M Kondo, YL Yu, T Ikeda

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   45 ( 9 )   1378 - 1382   2006

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    DOI: 10.1002/anie.200503684

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  • Photochemical Phase Transition Behavior of Highly Birefringent Azo-Tolane Liquid-Crystalline Polymer Films: Effects of the Position of the Tolane Group and the Donor-Acceptor Substituent in the Mesogen

    K. Okano, A, Shishido T. Ikeda

    Macromolecules   39 ( 1 )   145 - 152   2006

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  • White Emission from Liquid-Crystalline Copolymers Containing Oxadiazole Moieties in the Side Chain

    M. Kawamoto, T, Tsukamoto, M, Kinoshita T. Ikeda

    Appl. Phys. Lett.   89   121920/1-121920/3   2006

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  • An Azotolane Liquid-Crystalline Polymer Exhibiting Extremely Large Birefringence and Its Photoresponsive Behavior

    K. Okano, A, Shishido T. Ikeda

    Adv. Mater.   18 ( 4 )   523 - 527   2006

  • Synthesis and spectroscopic properties of amphiphilic diblock copolymer bearing a 2,5-diarylthiazole moiety

    Junichi Shikuma, Kohtaro Osakada, Motoi Kinoshita, Tomiki Ikeda, Sadayuki Asaoka, Tomokazu Iyoda, Atsunori Mori

    Polymer Preprints, Japan   55 ( 1 )   1532   2006

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    We have recently reported that amphiphilic diblock copolymers, which consist of PEO and azobenzene containing methacrylate form a highly ordered hexagonal-packed PEO cylinder structure in a nano-scale. We synthesized new amphiphilic diblock copolymer bearing a fluorescent 2,5-diarylthiazole moiety by ATRP with PEO-114BMP as an initiator. The obtained polymer shows Mn of 11,000-26,000 (Mw/Mn of 1.05-1.09). Measurement of UV-Vis and fluorescence spectra of the film of thus obtained diblock copolymer was also carried out before and after annealing.

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  • Surface Relief Grating Couplers Using Azobenzene Liquid-Crystalline Polymer Film

    C. -U. Bang, H. Kurihara, A, Shishido T. Ikeda

    Mol. Cryst. Liq. Cryst.   458   149 - 159   2006

  • Surface Relief Grating Couplers Using Azobenzene Liquid-Crystalline Polymer Film

    C. -U. Bang, H. Kurihara, A, Shishido T. Ikeda

    Mol. Cryst. Liq. Cryst.   458   149 - 159   2006

  • Novel amphiphilic diblock and triblock liquid-crystalline copolymers with well-defined structures prepared by atom transfer radical polymerization

    HF Yu, A Shishido, T Ikeda, T Iyoda

    MACROMOLECULAR RAPID COMMUNICATIONS   26 ( 20 )   1594 - 1598   2005.10

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    Based on a hydrophilic poly(ethylene oxide) macroinitiator (PEOBr), a novel amphiphilic diblock copolymer PEO-block-poly(11-(4-cyanobiphenyloxy)undecyl) methacrylate) (PEO-b-PMA(11CB)) was prepared by atom transfer radical polymerization (ATRP) using CuCl/1,1,4,7,10,10-hexamethyltriethylenetriamine as a catalyst system. An azobenzene block of poly(11-[4-(4-butylphenylazo)phenoxyl]undecyl methacrylate) was then introduced into the copolymer sequence by a second ATRP to synthesize the corresponding triblock copolymer PEO-b-PMA(11CB)-b-PMA(11Az). Both of the amphiphilic block copolymers had well-defined structures and narrow molecular-weight distributions, and exhibited a smectic liquid-crystalline phase over a wide temperature range.

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  • PD18 Effect of Azobenzene Concentration on Photoinduced Bending Behavior of Liquid-Crystalline Elastomer with a Side-Chain Azobenzene Moiety

    SUGIMOTO Manabu, MAMIYA Jun-ichi, KINOSHITA Motoi, Yu Yanlei, IKEDA Tomiki

    ( 2005 )   429 - 430   2005.9

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  • 3C09 Effect of structures of mesogenic groups in azo-tolane liquid-crystalline polymers on photoresponsive behavior

    OKANO Kunihiko, SHISHIDO Atsushi, IKEDA Tomiki

    ( 2005 )   223 - 224   2005.9

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  • 3C07 Preparation and Photoresponsive Behavior of Liquid-Crystalline Polymers with Inverse Opal Photonic Crystal Structures

    ISHIKAWA Kentaro, SHISHIDO Atsushi, IKEDA Tomiki

    ( 2005 )   219 - 220   2005.9

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  • PD16 Synthesis and Photoresponsive Behavior of Azobenzene Liquid-Crystalline Polymers with a Thienylacetylene Moiety

    HACHISUKA Yu, OKANO Kunihiko, SHISHIDO Atsushi, IKEDA Tomiki

    ( 2005 )   425 - 426   2005.9

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  • 3C03 Preparation of Microlens by Photoinduced Reorientation in Oligothiophene-Doped Liquid Crystals

    YAEGASHI Masahiro, SHISHIDO Atsushi, IKEDA Tomiki

    ( 2005 )   211 - 212   2005.9

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  • 3C08 Change of selective reflection in azobenzene liquid-crystalline polymers containing a chiral moiety

    SATO Junya, KINOSHITA Motoi, IKEDA Tomiki

    ( 2005 )   221 - 222   2005.9

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  • 2C06 Formation of holographic gratings in a chiral nematic liquid-crystalline polymer

    NAKAHARA Kenichi, KINOSHITA Motoi, IKEDA Tomiki

    ( 2005 )   141 - 142   2005.9

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  • Enhancement of surface-relief gratings recorded on amphiphilic liquid-crystalline diblock copolymer by nanoscale phase separation

    HF Yu, K Okano, A Shishido, T Ikeda, K Kamata, M Komura, T Iyoda

    ADVANCED MATERIALS   17 ( 18 )   2184 - 2188   2005.9

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    DOI: 10.1002/adma.200500346

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  • Photodeformable polymers: A new kind of promising smart material for micro- and nano-applications

    YL Yu, T Ikeda

    MACROMOLECULAR CHEMISTRY AND PHYSICS   206 ( 17 )   1705 - 1708   2005.9

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    Starting in the 1960s, several kinds of photodeformable polymers have been developed, such as monolayers, polymer gels, solid films elastomers with different photodeformation mechanisms. This field evolved slowly until recently when significant achievements have been made. Most recently, Lendlein and co-morkers have put forward another new concept - using photo-crosslinking to prepare deformable polymers with various pre-determined shapes (Nature 2005, 434, 879). This highlight gives a general introduction into photodeformable polymers and brings forth future challenges.

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  • Effect of ester moieties in dye structures on photoinduced reorientation of dye-doped liquid crystals

    M Yaegashi, A Shishido, T Shiono, T Ikeda

    CHEMISTRY OF MATERIALS   17 ( 17 )   4304 - 4309   2005.8

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    The photoinduced reorientation behavior of dye-doped nematic liquid crystals (LCs) was investigated. Thiophene derivatives with ester moieties were newly synthesized as the guest dye molecule. The liquid-crystalline behavior and optical properties of these compounds were evaluated, and the effect of the dye structure on the photoinduced reorientation behavior of the dye-doped LCs was investigated. The photoinduced formation of diffraction rings was observed as a result of the self-phase modulation effect at the intensity of 11 W/cm(2), when an Ar+ laser beam at 488 nm was irradiated above the threshold intensity. Comparison of the lowest threshold light intensity for the appearance of the diffraction rings revealed that the thiophene dye with ester moieties directly bound to the terminal thiophene shows a lower threshold intensity than those of any other dyes.

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  • Charge carrier transport properties in polymer liquid crystals containing oxadiazole and amine moieties in the same side chain

    M Kawamoto, H Mochizuki, T Ikeda, H Iino, J Hanna

    JOURNAL OF PHYSICAL CHEMISTRY B   109 ( 19 )   9226 - 9230   2005.5

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    Steady-state and transient photocurrent measurements were carried out to study the charge carrier transport properties of polymer liquid crystal (LC) containing oxadiazole (OXD) and amine moieties in the same side chain. The steady-state photocurrent measurement with asymmetric electrodes of ITO and A1 and a short penetration depth of the illumination light indicated that both electrons and holes can be transported in this film. The transient hole photocurrent observed by time-of-flight (TOF) experiments was dispersive at room temperature. The hole drift mobility significantly depended on temperature and electric field and was determined to be 6.1 x 10(-8) cm(2)/Vs at a field of 9.1 x 10(5) V/cM. According to the disorder formalism, the Gaussian width of the density of states was determined to be 170 meV for holes. Despite the indication of possible electron transport in this film, we could not determine the electron mobility by TOF experiments due to strong dispersive photocurrent. We discuss the present charge transport properties of the film in relation to a large dipole attributed to an electrical push-pull structure of p-dimethylaminophenyl-substitited OXD moiety in polymer LC and its electroluminescent properties.

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  • Polymerization of propylene with [t-BuNSiMe(2)Ind]TiMe2-MAO catalyst systems

    K Nishii, T Ikeda, M Akita, T Shiono

    JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL   231 ( 1-2 )   241 - 246   2005.4

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    ansa-Indenylamidodimethyltitanium complex ([t-BuNSiMe(2)Ind]TiMe2:1) was synthesized by one-pot reactions starting from the ligand, MeLi and TiCl4. The structure of 1 was determined by X-ray crystallography and the results obtained revealed that the indenyl ligand coordinate to titanium in an eta(4)-tendency. Propylene polymerization was conducted with I in toluene or heptane as solvent at 0 degrees C in the presence of dried methylaluminoxane (MAO) or dried modified MAO (MMAO), which was prepared from the toluene solutions of MAO or MMAO by removing free trialkylaluminium contained. Polymerization behavior was investigated from the consumption rate of propylene in a semi-batch system. The dried MAO/toluene system showed the highest activity without any deactivation. The produced polymer in the dried MAO/toluene system had the highest molecular weight and narrowest molecular weight distribution. The number-average molecular weight of the polymer increased almost linearly with increasimg polymerization time accompanied by narrowing molecular weight distribution from 1.42 to 1.37 and the number of polymer chains was almost constant. Thus, it was found that quasi-living polymerization of propylene proceeded. The C-13 NMR measurement indicated that 1-dried MAO/toluene produced poly(propylene) with isotactic triad of 40%. (c) 2005 Elsevier B.V. All rights reserved.

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  • Random copolymerization of propene and norbornene with ansa-fluorenylamidodimethyltitanium-based catalysts

    T Hasan, T Ikeda, T Shiono

    MACROMOLECULES   38 ( 4 )   1071 - 1074   2005.2

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    Copolymerization of propene and norbornene (P-N) was conducted with (t-BuNSiMe2Flu)-TiMe2 (1) activated by Me3Al-free methylaluminoxane (dried MAO), modified methylaluminoxane (MMAO), and Ph3CB(C6F5)(4)/OCt(3)Al at 20degreesC under atmospheric pressure of propene. The 1-Ph3CB(C6F5)(4)/OCt(3)Al system showed the highest activity and gave the copolymer with the lowest molecular weight and broad molecular weight distribution. The 1-dried MAO system produced the copolymer with the narrowest molecular weight distribution. The detailed investigation of this system clarified that the norbornene content in the copolymer was almost proportional to the N/P feed ratio with a narrow polydispersity of 1.1-1.2 and the glass transition temperatures of the P-N copolymers increased linearly against the norbornene content in the copolymers, that is, 53degreesC with 17 mol % of norbornene and 249degreesC with 71 mol % of norbornene. The C-13 NMR spectra also suggested the random distribution of the comonomers in the copolymers obtained.

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  • Preparation and characterization of azobenzene liquid-crystalline elastomer films with homeotropic alignment

    M Kondo, T Maeda, A Shishido, T Ikeda, YL Yu, M Nakano, T Shiono

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   441   297 - +   2005

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    Azobenzene liquid-crystalline elastomer (LCE) films with homeotropic alignment were prepared by in-situ photopolymerization of mixtures of an LC monomer and a cross linker, both of which contain azobenzene chromophores. Thermodynamic and mesomorphic properties of the monomers and the LCE films were determined by differential scanning calorimertry and polarizing optical microscopy. X-ray diffraction patterns revealed that the LCE films show a smectic A phase. Polarized UV spectra and conoscopic observation with a polarizing optical microscope demonstrated that the azobenzene mesogens are aligned homeotropically in the films.

    DOI: 10.1080/15421400500205787

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  • Synthesis and electroluminescent properties of liquid-crystalline polymers containing oxadiazole and carbazole moieties in the same side chain

    YM Nam, M Kinoshita, T Ikeda, M Kawamoto, T Shiono

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   443   95 - 104   2005

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    Liquid-crystalline polymers containing an oxadiazole moiety as an electron-transporting unit and a carbazole moiety as a hole-transporting unit in the same side chain were designed and synthesized to investigate electroluminescent (EL) properties. The synthesized polymers showed high fluorescence quantum efficiency. Furthermore, it was found that the luminescent polymers possessed bipolar carrier-transporting property. The single-layer organic light-emitting diode was fabricated to demonstrate EL emission. The device, ITO glass/the polymer/MgAg, exhibited intense blue emission with a maximum brightness of 30 cd/m(2) at 30 V.

    DOI: 10.1080/15421400500247318

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  • Synthesis and electroluminescent properties of liquid-crystalline polymers containing oxadiazole and carbazole moieties in the same side chain

    YM Nam, M Kinoshita, T Ikeda, M Kawamoto, T Shiono

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   443   95 - 104   2005

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    Liquid-crystalline polymers containing an oxadiazole moiety as an electron-transporting unit and a carbazole moiety as a hole-transporting unit in the same side chain were designed and synthesized to investigate electroluminescent (EL) properties. The synthesized polymers showed high fluorescence quantum efficiency. Furthermore, it was found that the luminescent polymers possessed bipolar carrier-transporting property. The single-layer organic light-emitting diode was fabricated to demonstrate EL emission. The device, ITO glass/the polymer/MgAg, exhibited intense blue emission with a maximum brightness of 30 cd/m(2) at 30 V.

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  • Novel liquid-crystalline phenylene-thienylene co-oligorners for photoinduced reorientation of liquid crystals

    M Yaegashi, A Shishido, T Ikeda, T Shiono

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   441   201 - +   2005

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    Several kinds of symmetric and asymmetric phenylene-thienylene co-oligomers substituted with alkyl, alkoxy, ester or cyano groups in the ends were newly synthesized. Liquid-crystalline (LC) properties of these compounds were evaluated by differential scanning calorimetry and polarizing optical microscopy. It was found that all the compounds showed an LC phase. The photoinduced reorientation behavior of the dye-doped nematic LCs was investigated upon exposure to an Ar+ laser beam at 488 nm. The change in refractive index was estimated to be larger than 0.1. It was revealed that the dyes synthesized act as an efficient trigger for the photoinduced reorientation.

    DOI: 10.1080/154214091009752

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  • Novel liquid-crystalline phenylene-thienylene co-oligorners for photoinduced reorientation of liquid crystals

    M Yaegashi, A Shishido, T Ikeda, T Shiono

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   441   201 - +   2005

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    Several kinds of symmetric and asymmetric phenylene-thienylene co-oligomers substituted with alkyl, alkoxy, ester or cyano groups in the ends were newly synthesized. Liquid-crystalline (LC) properties of these compounds were evaluated by differential scanning calorimetry and polarizing optical microscopy. It was found that all the compounds showed an LC phase. The photoinduced reorientation behavior of the dye-doped nematic LCs was investigated upon exposure to an Ar+ laser beam at 488 nm. The change in refractive index was estimated to be larger than 0.1. It was revealed that the dyes synthesized act as an efficient trigger for the photoinduced reorientation.

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  • Photoinduced bending of polymer films Reviewed

    Tomiki Ikeda, Taketo Maeda, Mizuho Kondo, Yanlei Yu

    Proceedings of SPIE - The International Society for Optical Engineering   5947   1 - 8   2005

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    Photoinduced bending and unbending behavior of cross-linked polymer films, prepared by in-situ polymerization of liquid-crystalline (LC) monomers with azobenzene moieties, is discussed. Various modes of bending have been achieved with various alignments of the photoactive mesogens in the elastomers. Exposure of a monodomain film to UV light to cause trans-cis isomerization of the azobenzene moieties leads to the bending of the film toward irradiation direction of the actinic light. Irradiation of a polydomain film with linearly polarized light results in the bending along the polarization direction of the light, which enables bending of the film along any direction. The LC alignment in the films significantly affected the photoinduced bending behavior.

    DOI: 10.1117/12.622440

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  • Side-chain liquid-crystalline polymers containing oxadiazole and amine moieties for organic light-emitting diode Reviewed

    Motoi Kinoshita, Masuki Kawamoto, Hiroyuki Mochizuki, Yunmi Nam, Tomiki Ikeda

    Proceedings of SPIE - The International Society for Optical Engineering   5936   1 - 8   2005

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    To create polarized organic light emitting diodes (OLEDs), liquid-crystalline polymers (LCPs) containing oxadiazole and amine moieties in the side chain were design and synthesized. These LCPs emitted intense blue fluorescence with high quantum yield over 0.6 in a solution. Furthermore, polarized emissions of fluorescence were observed in a LC phase, and order parameters estimated by the polarized emission were about 0.2. They have proven to function as polarized blue-emitting materials for OLEDs.

    DOI: 10.1117/12.620795

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  • Charge Carrier Transport Properties in Polymer Liquid Crystals Containing Oxadiazole and Amine Moieties in the Same Side Chain

    M. Kawamoto, H. Mochizuki T. Ikeda, H. Iino, J. Hanna

    J. Phys. Chem. B.   109 ( 19 )   9226 - 9230   2005

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  • Highly birefringent liquid-crystalline polymers for photonic applications: synthesis of liquid-crystalline polymers with side-chain azo-tolane mesogens and their holographic properties

    K Okano, A Shishido, O Tsutsumi, T Shiono, T Ikeda

    JOURNAL OF MATERIALS CHEMISTRY   15 ( 33 )   3395 - 3401   2005

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    Language:English   Publisher:ROYAL SOC CHEMISTRY  

    We have synthesized highly birefringent liquid-crystalline polymers (LCPs) containing an azobenzene group directly connected to a tolane moiety (P3ATm), in which the alkyl spacer length (CH2)(m) was varied as m 5 6, 9 and 12. All LCPs showed a nematic phase in a broad temperature range (> 170 degrees C). The homogeneously aligned LCP films showed a high value of birefringence ( about 0.4) and a large change in the birefringence could be induced by photoinduced alignment change. Grating formation of LCPs has been explored in a glassy state. The diffraction efficiency ( g) showed a maximum when an order-disorder change was completed in the bright areas of the interference patterns. Studies on the effects of light intensity on the grating formation suggested that the diffraction efficiency was high (eta = 20%) even though the alignment change of the azotolane moieties was small. Furthermore, the behavior of the grating formation was found to be dependent on the alkyl spacer length of P3ATm.

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  • Preparation and characterization of azobenzene liquid-crystalline elastomer films with homeotropic alignment

    M Kondo, T Maeda, A Shishido, T Ikeda, YL Yu, M Nakano, T Shiono

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   441   297 - +   2005

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    Azobenzene liquid-crystalline elastomer (LCE) films with homeotropic alignment were prepared by in-situ photopolymerization of mixtures of an LC monomer and a cross linker, both of which contain azobenzene chromophores. Thermodynamic and mesomorphic properties of the monomers and the LCE films were determined by differential scanning calorimertry and polarizing optical microscopy. X-ray diffraction patterns revealed that the LCE films show a smectic A phase. Polarized UV spectra and conoscopic observation with a polarizing optical microscope demonstrated that the azobenzene mesogens are aligned homeotropically in the films.

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  • Precisely direction-controllable bending of cross-linked liquid-crystalline polymer films by light

    YL Yu, M Nakano, T Maeda, M Kondo, T Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   436   1235 - 1244   2005

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    Cross-linked liquid-crystalline polymer films were prepared by polymerization of mixtures containing azobenzene monomers and cross-linkers with azobenzene moieties. Two types of the cross-linked liquid-crystalline polymer films were prepared: monodomain films and polydomains films. Photoirradiation of the monodomain films with UV linearly polarized light (LPL) gave rise to bending of the films toward actinic light along the polarization direction, when the light polarization was parallel to the rubbing direction. When the two directions were perpendicular to each other, the bending was isotropic without a preferential direction. On the other hand, exposure of the polydomain films to UV LPL led to bending of the films always along the polarization direction of the actinic light. This means that one can induce bending of the film along any direction precisely by choosing the polarization direction of the actinic light.

    DOI: 10.1080/15421400590957215

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  • Precisely direction-controllable bending of cross-linked liquid-crystalline polymer films by light

    YL Yu, M Nakano, T Maeda, M Kondo, T Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   436   1235 - 1244   2005

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    Cross-linked liquid-crystalline polymer films were prepared by polymerization of mixtures containing azobenzene monomers and cross-linkers with azobenzene moieties. Two types of the cross-linked liquid-crystalline polymer films were prepared: monodomain films and polydomains films. Photoirradiation of the monodomain films with UV linearly polarized light (LPL) gave rise to bending of the films toward actinic light along the polarization direction, when the light polarization was parallel to the rubbing direction. When the two directions were perpendicular to each other, the bending was isotropic without a preferential direction. On the other hand, exposure of the polydomain films to UV LPL led to bending of the films always along the polarization direction of the actinic light. This means that one can induce bending of the film along any direction precisely by choosing the polarization direction of the actinic light.

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  • Highly birefringent liquid-crystalline polymers for photonic applications: synthesis of liquid-crystalline polymers with side-chain azo-tolane mesogens and their holographic properties

    K Okano, A Shishido, O Tsutsumi, T Shiono, T Ikeda

    JOURNAL OF MATERIALS CHEMISTRY   15 ( 33 )   3395 - 3401   2005

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    We have synthesized highly birefringent liquid-crystalline polymers (LCPs) containing an azobenzene group directly connected to a tolane moiety (P3ATm), in which the alkyl spacer length (CH2)(m) was varied as m 5 6, 9 and 12. All LCPs showed a nematic phase in a broad temperature range (> 170 degrees C). The homogeneously aligned LCP films showed a high value of birefringence ( about 0.4) and a large change in the birefringence could be induced by photoinduced alignment change. Grating formation of LCPs has been explored in a glassy state. The diffraction efficiency ( g) showed a maximum when an order-disorder change was completed in the bright areas of the interference patterns. Studies on the effects of light intensity on the grating formation suggested that the diffraction efficiency was high (eta = 20%) even though the alignment change of the azotolane moieties was small. Furthermore, the behavior of the grating formation was found to be dependent on the alkyl spacer length of P3ATm.

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  • Synthesis and properties of highly birefringent azo-tolane liquid-crystal line polymers: Effect of the position of the tolane moiety in the side chain

    K Okano, A Shishido, T Ikeda, T Shiono

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   441   275 - +   2005

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    We have synthesized two types of azobenzene liquid-crystalline polymers with a tolane moiety exhibiting high birefringence: one is the copolymer having an azobenzene moiety and a 3-ring tolane group in the side chain (PA-3T) and the other is the polymer containing a long mesogen core, in which the azobenzene group is directly connected to the tolane moiety (P3AT). The values of 0.35 and 0.39 in birefringence were obtained in PA-3T and MAT, respectively. When the film was irradiated with a writing beam at 488 nm, the change in birefringence was efficiently induced with P3AT compared with PA-3T.

    DOI: 10.1080/154214091009932

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  • Synthesis and Properties of Highly Birefringent Azo-Tolane Liquid-Crystalline Polymers: Effect of the Position of the Tolane Moiety in the Side Chain

    K. Okano, A, Shishido T, Shiono T. Ikeda

    Mol. Cryst. Liq. Cryst.   441   275 - 285   2005

  • Photoinduced Change in Birefringence and Optical Switching at Near-Infrared Region Based on Photochemical Phase Transition of Azobenzene Liquid Crystals

    H. Kurihara, A. Shishido, O. Tsutsumi T, Shiono T. Ikeda

    Mol. Cryst. Liq. Cryst.   441   173 - 184   2005

  • Photoinduced Alignment Behavior of Poly(alkyl methacrylates) Containing Azobenzene Moiety in the Side Chain

    H. -B. Cha, A, Shishido T, Shiono T. Ikeda

    Mol. Cryst. Liq. Cryst.   443   201 - 209   2005

  • Effect of Intensity of Actinic Light and Temperature on Photochemical Phase Transition of Azobenzene Liquid Crystals Probed by a Near-Infrared Laser Beam

    H. Kurihara, A. Shishido, O. Tsutsumi T, Shiono T. Ikeda

    Mol. Cryst. Liq. Cryst.   443   229 - 238   2005

  • Effect of Intensity of Actinic Light and Temperature on Photochemical Phase Transition of Azobenzene Liquid Crystals Probed by a Near-Infrared Laser Beam

    H. Kurihara, A. Shishido, O. Tsutsumi T, Shiono T. Ikeda

    Mol. Cryst. Liq. Cryst.   443   229 - 238   2005

  • Photoinduced Alignment Behavior of Poly(alkyl methacrylates) Containing Azobenzene Moiety in the Side Chain

    H. -B. Cha, A, Shishido T, Shiono T. Ikeda

    Mol. Cryst. Liq. Cryst.   443   201 - 209   2005

  • Photoinduced Change in Birefringence and Optical Switching at Near-Infrared Region Based on Photochemical Phase Transition of Azobenzene Liquid Crystals

    H. Kurihara, A. Shishido, O. Tsutsumi T, Shiono T. Ikeda

    Mol. Cryst. Liq. Cryst.   441   173 - 184   2005

  • Photoresponsive Behavior and Photochemical Phase Transition of Amphiphilic Diblock Liquid-Crystalline Copolymer

    H. Yu, K. Okano, A, Shishido T, Ikeda K, Watanabe, T. Iyoda

    Mol. Cryst. Liq. Cryst.   443   191 - 199   2005

  • Photoresponsive Behavior and Photochemical Phase Transition of Amphiphilic Diblock Liquid-Crystalline Copolymer

    H. Yu, K. Okano, A, Shishido T, Ikeda K, Watanabe, T. Iyoda

    Mol. Cryst. Liq. Cryst.   443   191 - 199   2005

  • Synthesis and investigation of photophysical and photochemical properties of new side-group liquid crystalline polymers containing coumarin moieties

    Yanqing Tian, Eiichi Akiyama, Yu Nagase, Akihiko Kanazawa, Osamu Tsutsumi, Tomiki Ikeda

    Journal of Materials Chemistry   14 ( 24 )   3524 - 3531   2004.12

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    Four coumarin (2-oxo-2H-1-benzopyran) containing liquid crystalline polymethacrylates possessing the same monomer formula but different linkage directions and/or construction directions of their mesogens into the same main-chain were prepared and investigated. Each of the four polymers exhibits a smectic A liquid crystalline phase. The change of construction and/or linkage directions significantly affected their liquid crystalline properties. Especially, the change of the construction directions of the mesogens caused different photophysical and photochemical properties.

    DOI: 10.1039/b408554j

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  • Alignment modulation of azobenzene-containing liquid crystal systems by photochemical reactions

    YL Yu, T Ikeda

    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS   5 ( 3 )   247 - 265   2004.12

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    Language:English   Publishing type:Book review, literature introduction, etc.   Publisher:ELSEVIER SCIENCE BV  

    Recent progress in alignment modulation of azobenzene-containing liquid crystal systems by photochemical reactions has been reviewed by dividing the modulation methods into two types: phase transitions (order-disorder change) and change of liquid crystal directors (order-order change). First, photochemical phase transitions and alignment changes of liquid crystals in guest/host mixtures and polymers are summarized. Then, alignment control of liquid crystals by linearly polarized light and photoactive surface layers is discussed. Finally, recent applications of alignment change and photochemical phase transitions of liquid crystals in holographic technology and photomechanical effects are introduced. In addition, future possible applications for a variety of practical devices, such as display devices, optical switching and reversible optical image storage, are mentioned. (C) 2004 Japanese Photochemistry Association. Published by Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jphotochemrev.2004.10.004

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  • Self-Assembled Molecular Aggregates of Rod-Like Organogelators Containing a Mesogen Moiety

    MAMIYA Jun-ichi, KATO Takashi, IKEDA Tomiki

    Technical report of IEICE. OPE   104 ( 333 )   29 - 32   2004.10

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    Language:Japanese   Publisher:The Institute of Electronics, Information and Communication Engineers  

    A mesogenic compound (1) with a syw-chiral carbonate moiety was synthesized. The self-assembly process of the azobenzene LC with a simple structure without hydrogen bonds or stacking of cholesterol was investigated. 1 shows excellent gelation properties for various organic solvents. The gelation ability of the compound is due to the formation of one-dimensional fibrous structures. The fibrous self-assembled structure was formed by the ribbon-like aggregation of 1 through the dipole-dipole interactions of the chiral carbonate moieties. Furthermore, the photoresponsive behavior of physicalorganogels formed by the azobenzene gelator was investigated.

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  • Electroluminescent Behavior of Liquid-Crystalline Materials Showing Bipolar Carrier-Transporting Properties

    KAWAMOTO Masuki, IKEDA Tomiki

    Technical report of IEICE. OPE   104 ( 333 )   17 - 21   2004.10

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    Language:Japanese   Publisher:The Institute of Electronics, Information and Communication Engineers  

    We designed and synthesized novel liquid-crystalline (LC) materials containing an oxadiazole moiety as an electron-transporting unit and an amine moiety as a hole-transporting unit in a single unit. The most significant characteristic of the LCs is to possess bipolar carrier-transporting abilities. Electroluminescent (EL) devices were fabricated with a simple configuration of ITO/LC/MgAg to demonstrate EL behavior. Furthermore, the polarized EL was observed due to self-assemblies of mesogenic chromophores. Especially we found that a rubbed semi-conducting polymer layer acts not only as a hole-injecting layer but also as an LC alignment layer.

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  • Highly efficient Ti-based catalyst systems for vinyl addition polymerization of norbornene

    T Hasan, T Ikeda, T Shiono

    MACROMOLECULES   37 ( 20 )   7432 - 7436   2004.10

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    Received March 18, 2004; Revised Manuscript Received July 22, 2004 Norbornene polymerization via "vinyl addition" proceeded with (t-BuNSiMe(2)Flu)TiMe(2) (1) in the presence of various cocatalysts [methylaluminoxane (MAO), modified methylaluminoxane (MMAO), and Ph(3)CB(C(6)F(5))(4)/Oct(3)Al] at wide range of temperatures (20-80degreesC) with high activity. The 1-Ph(3)CB-(C(6)F(5))(4)/Oct(3)Al system produced 4.8 x 10(3) kg of polymer per mole of Ti per hour at 20degreesC. All the catalyst systems produced high molecular weight (M(n)) polymers. In the 1-MMAO system the yield and M values increased linearly keeping narrow molecular weight distribution against the Al/Ti ratio, suggesting that MMAO should take part not only in the initiation but also in the propagation reaction. The rate enhancement with higher Al/Ti ratio was also observed in the Ph(3)CB(C(6)F(5))(4)/Oct(3)Al system. The activity of the 1-dried MAO and 1-MMAO systems increased with raising reaction temperature up to 60degreesC, whereas that of 1-Ph(3)CB(C(6)F(5))(4)/Oct(3)Al decreased. The polynorbornenes obtained with 1 were amorphous, soluble in halogenated aromatic solvents, and stable up to 420degreesC. The film of polynorbornene prepared by solvent casting was highly transparent in the UV-vis region.

    DOI: 10.1021/ma049455p

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  • 1C11 Photoinduced Bending of Azobenzene Liquid-Crystalline Elastomer Films : Photoresponsive Behavior of a Homeotropically Aligned Film

    KONDO Mizuho, MAEDA Taketo, YU Yanlei, SHISHIDO Atsushi, SHIONO Takeshi, IKEDA Tomiki

    ( 2004 )   216 - 217   2004.9

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    Homeotropically aligned azobenzene liquid-crystalline elastomer (LCE) films were prepared and investigated in terms of the photoinduced bending behavior. Upon irradiation of UV light which induces photoisomerization of the azobebzene moieties, the film bent away from the UV light and reverted to the initial state when irradiated at visible light, contrary to the bending behavior of a homogeneous film. This can be explained by a different volume transformation.

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  • 1C15 Formation of Gratings by Holographic Photopolymerization of Ferroelectric Liquid-Crystalline Monomers

    IKEDA Koujiro, SHISHIDO Atsushi, SHIONO Takeshi, IKEDA Tomiki

    ( 2004 )   224 - 225   2004.9

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    Photopolymerization of ferroelectric liquid-crystalline monomers was carried out under an electric field. Upon photoirradiation of an Ar^+ laser beam at 488 nm, a monomer mixture in a 2-μm cell was polymerized and the initial molecular alignment was stabilized. Next, two beams at 488 nm were interfered in the cell, and the light intensity of the first-order diffraction light of a He-Ne laser beam at 633 nm was measured. The diffracted light appeared due to the grating formation. By applying an electric field, the intensity of the diffraction light increased, indicating a change in alignment of the unreacted monomers.

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  • 1C14 Formation of Holographic Bragg Gratings in Polymer Azobenzene Films Containing a Tolane Moiety

    ISHIGURO Makoto, SHISHIDO Atsushi, SHIONO Takeshi, IKEDA Tomiki

    ( 2004 )   222 - 223   2004.9

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    Polymer azobenzene films containing various contents of a tolane moiety with large birefringence were prepared. Two linearly polarized beams of an Ar^+ laser (488 nm) were interfered in the film, and the light intensity of the first-order diffraction of a He-Ne laser beam (633 nm) was measured. In the film with thickness of 100 μm, the diffraction efficiency reached 99.2% when photoirradiation was performed at 200 mW/cm^2 for 13 min. The maximum diffraction efficiency was significantly influenced by the content of the tolane moiety.

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  • 2B02 Grating Formation Based on Bragg Diffraction in Polymer Films Containing a Donor-Accepter Type Azobenzene Moiety

    SAISHOJI Aya, SHISHIDO Atsushi, SHIONO Takeshi, IKEDA Tomiki

    ( 2004 )   230 - 231   2004.9

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    Polymer films containing a donor-accepter type azobenzene moiety were prepared and formation of gratings based on a photoinduced change in refractive index was explored. When two linearly polarized beams of an Ar^+ laser (514 nm) were interfered in the CB30AB5 film (film thickness : 250 μm), the diffraction beam based on Bragg diffraction appeared immediately. The maximum diffraction efficiency reached 98% upon photoirradiation at 100 mW/cm^2 for 6 min. It was clearly observed that the response time became shorter with an increase in the light intensity of the writing beams, maintaining the high diffraction efficiency. Furthermore, holographic multiple data storages in the CB30AB5 film were demonstrated.

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  • 1C12 Flexible Liquid Crystal Hologram : Holographic Recording in Plastic Polymer Films

    SHIMURA Shin-ichiro, SHISHIDO Atsushi, SHIONO Takeshi, IKEDA Tomiki, FUJIKAKE Hideo, SATO Hiroto

    ( 2004 )   218 - 219   2004.9

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    A flexible liquid crystal hologram was prepared as a novel type of holographic materials. Polycarbonate films covered with a polyimide were employed as a substrate, and toluene solution of a polymer azobenzene liquid crystal (PALC) was coated on the rubbed substrate, resulting in a flexible PALC film. We attempted the formation of gratings and holographic image storage of 3-D objects into the flexible film. A clear and bright 3-D image was successfully reconstructed even in the bent film. This indicates that the holographic diffraction grating is formed in the flexible PALC film.

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  • 3C02 Preparation of Photonic Crystal Structure Using Liquid-Crystalline Polymer Particles and its Optical Responsiveness

    TSURUMA Takeyuki, SHISHIDO Atsushi, IKEDA Tomiki

    ( 2004 )   246 - 247   2004.9

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    Photonic crystal structures were formed by polymer particles containing azobenzene moieties and their optical responsiveness was investigated. A Bragg diffraction peak due to the periodic structure was observed in the PME3-30 film in the reflection spectrum. A change in the intensity of the diffraction peak was induced by irradiation of a linearly polarized beam at 488 nm. The observation of the film by SEM revealed the adhesion of the polymer particles induced by photoirradiation.

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  • Optically switchable Bragg reflectors

    A Urbas, J Klosterman, Tondiglia, V, L Natarajan, R Sutherland, S Tsutsumi, T Ikeda, T Bunning

    ADVANCED MATERIALS   16 ( 16 )   1453 - +   2004.8

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    One-dimensional holographic photonic crystals that incorporate photochromic azobenzene-derived liquid crystals azobenzene-derived liquid crystals (LCs) have been produced. The additive photochromic molecules disrupt the host LC nematic order, inducing an isothermal phase transition and changing the effective dielectric properties of the LC layer (see Figure). This imparts photo-optic properties to the structure, allowing for its reflectivity to be modulated with exposure to light.

    DOI: 10.1002/adma.200400206

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  • Photoinduced bending and unbending behavior of liquid-crystalline gels and elastomers

    YL Yu, M Nakano, T Ikeda

    PURE AND APPLIED CHEMISTRY   76 ( 7-8 )   1467 - 1477   2004.7

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    Language:English   Publisher:INT UNION PURE APPLIED CHEMISTRY  

    Liquid-crystalline gels and elastomers were prepared by polymerization of mixtures containing azobenzene monomers and cross linkers with azobenzene moieties. Oriented liquid-crystalline gels and elastomer films were found to undergo anisotropic bending and unbending behavior only along the rubbing direction, when exposed to alternate irradiation of unpolarized UV and visible light. In the case of polydomain liquid-crystalline elastomer films, the bending and unbending were induced exactly along the polarization direction of incident linearly polarized light. By altering the polarization direction of light, a single film could be bent repeatedly and precisely along any chosen direction.

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  • Living random copolymerization of ethene and norbornene using ansa-fluorenylamidodimethyltitanium complex

    T Hasan, T Shiono, T Ikeda

    MACROMOLECULAR SYMPOSIA   213   123 - 129   2004.6

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    Language:English   Publisher:WILEY-V C H VERLAG GMBH  

    Ethene-norbornene copolymerizations were conducted by (tBuNMe(2)SiFlu)TiMe2 (1) activated with dried methylaluminoxane (MAO) (free from Me3Al) at 0 degreesC and 20 degreesC under atmospheric pressure of ethene at various norbornene concentrations. At 0 degreesC and high norbornene concentration, the molecular weight of the copolymer increased linearly against polymerization time while keeping narrow molecular-weight distribution. The C-13 NMR spectrum revealed that random copolymer with 53 mol-% of norbornene was obtained. The glass transition temperature was above 150 degreesC.

    DOI: 10.1002/masy.200450913

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  • Syntheses and properties of donor-acceptor-type 2,5-diarylthiophene and 2,5-diarylthiazole

    K Masui, A Mori, K Okano, K Takamura, M Kinoshita, T Ikeda

    ORGANIC LETTERS   6 ( 12 )   2011 - 2014   2004.6

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    Syntheses of differently substituted 2,5-diarylthiophenes and 2,5-diarylthiazoles are carried out with the palladium-catalyzed C-H substitution reaction using AgF as an activator. Remarkably strong photoluminescence is observed in 2,5-diarylthiophene. Differences between the physical properties of liquid crystalline characteristics and cyclic voltammograms of thiophene and thiazole are also studied.

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  • Syntheses and properties of donor-acceptor-type 2,5-diarylthiophene and 2,5-diarylthiazole

    K Masui, A Mori, K Okano, K Takamura, M Kinoshita, T Ikeda

    ORGANIC LETTERS   6 ( 12 )   2011 - 2014   2004.6

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    Syntheses of differently substituted 2,5-diarylthiophenes and 2,5-diarylthiazoles are carried out with the palladium-catalyzed C-H substitution reaction using AgF as an activator. Remarkably strong photoluminescence is observed in 2,5-diarylthiophene. Differences between the physical properties of liquid crystalline characteristics and cyclic voltammograms of thiophene and thiazole are also studied.

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  • A novel synthetic procedure for stereoblock poly(propylene) with a living polymerization system

    K Nishii, T Shiono, T Ikeda

    MACROMOLECULAR RAPID COMMUNICATIONS   25 ( 10 )   1029 - 1032   2004.5

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    Propylene polymerization was conducted at 0degreesC in heptane or chlorobenzene (CB) by an ansa-fluorenylami-dodimethyltitanium complex combined with dried, modified methylaluminoxane that had been treated by dilution with heptane and successively repeatedly vacuum dried to remove any free trialkylaluminiums. The post-polymerizations testified that the living polymerization proceeded irrespective of the solvent used. The heptane system gave the syndiotactic poly(proplene)s (PPs). whereas the CB system gave almost atactic PPs. After the first polymerizations in heptane had been completed, the same amounts of propylene and CB were added for the second polymerization. This procedure gave the sydiotactic stereoblock PP with narrow molecular-weight distributions.

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  • Effect of cross-linking density on photoinduced bending behavior of oriented liquid-crystalline network films containing azobenzene

    YL Yu, M Nakano, A Shishido, T Shiono, T Ikeda

    CHEMISTRY OF MATERIALS   16 ( 9 )   1637 - 1643   2004.5

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    Oriented liquid-crystalline network films with various cross-linking densities were prepared by polymerization of mixtures of mono- and diacrylates, both of which contain azobenzene chromophores. The optical anisotropy in the films was evaluated by polarizing optical microscopy and polarized IR spectroscopy. The dichroic ratios and the order parameters of the films were estimated from polarized UV absorbance. The free-standing films were found to show photoinduced bending and unbending behavior upon alternate exposure to unpolarized UV light at 366 nm and unpolarized visible light at > 540 nm. It was observed that the films with different cross-linking densities exhibited different bending extents and speeds.

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  • Effect of cross-linking density on photoinduced bending behavior of oriented liquid-crystalline network films containing azobenzene

    YL Yu, M Nakano, A Shishido, T Shiono, T Ikeda

    CHEMISTRY OF MATERIALS   16 ( 9 )   1637 - 1643   2004.5

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    Oriented liquid-crystalline network films with various cross-linking densities were prepared by polymerization of mixtures of mono- and diacrylates, both of which contain azobenzene chromophores. The optical anisotropy in the films was evaluated by polarizing optical microscopy and polarized IR spectroscopy. The dichroic ratios and the order parameters of the films were estimated from polarized UV absorbance. The free-standing films were found to show photoinduced bending and unbending behavior upon alternate exposure to unpolarized UV light at 366 nm and unpolarized visible light at > 540 nm. It was observed that the films with different cross-linking densities exhibited different bending extents and speeds.

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  • A novel synthetic procedure for stereoblock poly(propylene) with a living polymerization system

    K Nishii, T Shiono, T Ikeda

    MACROMOLECULAR RAPID COMMUNICATIONS   25 ( 10 )   1029 - 1032   2004.5

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    Propylene polymerization was conducted at 0degreesC in heptane or chlorobenzene (CB) by an ansa-fluorenylami-dodimethyltitanium complex combined with dried, modified methylaluminoxane that had been treated by dilution with heptane and successively repeatedly vacuum dried to remove any free trialkylaluminiums. The post-polymerizations testified that the living polymerization proceeded irrespective of the solvent used. The heptane system gave the syndiotactic poly(proplene)s (PPs). whereas the CB system gave almost atactic PPs. After the first polymerizations in heptane had been completed, the same amounts of propylene and CB were added for the second polymerization. This procedure gave the sydiotactic stereoblock PP with narrow molecular-weight distributions.

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  • Photomechanical effects in azobenzene-containing polymer systems

    YL Yu, M Nakano, T Ikeda

    JOURNAL OF SYNTHETIC ORGANIC CHEMISTRY JAPAN   62 ( 5 )   471 - 479   2004.5

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    Several kinds of photodeformable polymer systems containing azobenzenes, capable of generating photomechanical effects, are reviewed. In polymer amorphous systems including monolayers, gels and solid films, trans-cis photoisomerization of the azobenzene moieties accompanied by geometrical and dipolar changes caused contraction and expansion of the systems. Recently, polymer liquid-crystalline elastomers containing azobenzenes, a novel system able to produce the photomechanical effects, have been developed to achieve fast and large photoinduced deformations. It is interesting that not only photoinduced contraction but also photoinduced bending have been achieved. These deformations are ascribed to the subtle variation in microscopic ordering during the photochemical phase transition of the polymer liquid-crystalline elastomers. This new photomechanical system is potential for application in driving micromachines and nanomachines without the aid of batteries, motors and gears.

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  • Effect of solvents on living polymerization of propylene with [t-BuNSiMe(2)Flu]TiMe2-MMAO catalyst system

    K Nishii, T Matsumae, EO Dare, T Shiono, T Ikeda

    MACROMOLECULAR CHEMISTRY AND PHYSICS   205 ( 3 )   363 - 369   2004.2

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    Batchwise polymerization of propylene was conducted at 0degreesC in heptane using [tert-BuNSiMe(2)Flu]- TiMe2 (1) combined with dried methylaluminoxane (MAO) and dried modified methylaluminoxane (MMAO), which were prepared from the toluene solutions of MAO and MMAO by removing the solvent and the free trialkylaluminium. The dried MMAO system quantitatively gave the polymer with higher molecular weight and narrower molecular weight distribution (MWD), ca. 1.3, compared with the dried MAO system. In addition, the polymerization with dried MMAO in toluene, chlorobenzene (CB) and ortho-dichlorobenzene (o-DCB), as solvent, also produced polymers quantitatively with MWD of ca. 1.1-1.3. The number average molecular weight ((M) over bar (n)) of the polymers, obtained with these systems, increased linearly against the polymer yield, while the narrow MWD was retained and the number of polymer chains was almost constant. The results of post-polymerization in heptane and o-DCB proved that the living polymerization proceeded irrespective of the solvent used. The semi-batch polymerizations under an atmospheric pressure of propylene indicated that the propagation rate was more than 10 times higher in o-DCB than in heptane. The C-13 NMR analysis of the polymers indicated that the syndiotacticity also depended on the polarity of the solvent and increased in the following order: CBless than or equal to o-DCB < toluene < heptane.

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  • Supporting effects of methylaluminoxane on the living polymerization of propylene with a chelating (diamide)dimethyltitanium complex

    H Hagimoto, T Shiono, T Ikeda

    MACROMOLECULAR CHEMISTRY AND PHYSICS   205 ( 1 )   19 - 26   2004.1

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    Modified methylaluminoxane (MMAO), from which free AlMe3 and Al(iBu)(3) were reduced to ca. 0.1 mol-%, was supported on metal oxides, such as anhydrous silica gel, alumina, or magnesia; the metal oxide-supported MMAO prepared were used as a cocatalysts for propylene polymerization combined with a chelating (diamide) dimethyltitanium complex. The systems conducted living polymerization of propylene at 0degreesC regardless of the support for MMAO. The propagation rate constants (k(p)) of these systems and the molecular weight distribution ((M) over bar (w)/(M) over bar (n)) of the produced polymer depended on the metal oxide employed. The XPS analysis of the supported MMAOs suggested that the k(p) value increased with the Lewis acidity of MMAO on the support and the broadening (M) over bar (w)/(M) over bar (n) was ascribed to the distribution of k(p) caused by the heterogeneity of the supported cocatalyst.

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  • Supporting effects of methylaluminoxane on the living polymerization of propylene with a chelating (diamide)dimethyltitanium complex

    H Hagimoto, T Shiono, T Ikeda

    MACROMOLECULAR CHEMISTRY AND PHYSICS   205 ( 1 )   19 - 26   2004.1

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    Modified methylaluminoxane (MMAO), from which free AlMe3 and Al(iBu)(3) were reduced to ca. 0.1 mol-%, was supported on metal oxides, such as anhydrous silica gel, alumina, or magnesia; the metal oxide-supported MMAO prepared were used as a cocatalysts for propylene polymerization combined with a chelating (diamide) dimethyltitanium complex. The systems conducted living polymerization of propylene at 0degreesC regardless of the support for MMAO. The propagation rate constants (k(p)) of these systems and the molecular weight distribution ((M) over bar (w)/(M) over bar (n)) of the produced polymer depended on the metal oxide employed. The XPS analysis of the supported MMAOs suggested that the k(p) value increased with the Lewis acidity of MMAO on the support and the broadening (M) over bar (w)/(M) over bar (n) was ascribed to the distribution of k(p) caused by the heterogeneity of the supported cocatalyst.

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  • Synthesis and investigation of photophysical and photochemical properties of new side-group liquid crystalline polymers containing coumarin moieties

    YQ Tian, E Akiyama, Y Nagase, A Kanazawa, O Tsutsumi, T Ikeda

    JOURNAL OF MATERIALS CHEMISTRY   14 ( 24 )   3524 - 3531   2004

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    Four coumarin (2-oxo-2H-1-benzopyran) containing liquid crystalline polymethacrylates possessing the same monomer formula but different linkage directions and/or construction directions of their mesogens into the same main-chain were prepared and investigated. Each of the four polymers exhibits a smectic A liquid crystalline phase. The change of construction and/or linkage directions significantly affected their liquid crystalline properties. Especially, the change of the construction directions of the mesogens caused different photophysical and photochemical properties.

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  • Synthesis and investigation of photophysical and photochemical properties of new side-group liquid crystalline polymers containing coumarin moieties

    YQ Tian, E Akiyama, Y Nagase, A Kanazawa, O Tsutsumi, T Ikeda

    JOURNAL OF MATERIALS CHEMISTRY   14 ( 24 )   3524 - 3531   2004

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    Four coumarin (2-oxo-2H-1-benzopyran) containing liquid crystalline polymethacrylates possessing the same monomer formula but different linkage directions and/or construction directions of their mesogens into the same main-chain were prepared and investigated. Each of the four polymers exhibits a smectic A liquid crystalline phase. The change of construction and/or linkage directions significantly affected their liquid crystalline properties. Especially, the change of the construction directions of the mesogens caused different photophysical and photochemical properties.

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  • Preparation of Monodispersed Polymer Particles Containing Azobenzene Moieties

    A. Shishido E. Miyamoto, T. Ikeda

    Trans. Mater. Res. Soc. Jpn.   29   903 - 905   2004

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  • Photofunctional Polymers Based on Cooperative Effects

    IKEDA Tomiki

    Kobunshi   53 ( 4 )   276 - 282   2004

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    DOI: 10.1295/kobunshi.53.276

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  • 光応答性液晶ゲルアクチュエーター

    中野誠, 兪燕蕾, 池田富樹

    液晶   8   75 - 85   2004

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  • Preparation of Monodispersed Polymer Particles Containing Azobenzene Moieties

    A. Shishido E. Miyamoto, T. Ikeda

    Trans. Mater. Res. Soc. Jpn.   29   903 - 905   2004

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  • Liquid-crystalline elastomers with photomechanical properties

    YL Ya, M Nakano, T Ikeda

    LIQUID CRYSTALS VIII   5518   1 - 10   2004

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    Photoinduced bending and unbending behavior of liquid-crystal line elastomers is discussed. Various modes of bending have been achieved with various alignments of the photoactive mesogens in the elastomers: oriented Liquid-crystalline elastomer films were found to undergo anisotropic bending and unbending behavior only along the rubbing direction, when exposed to alternate irradiation of unpolarized UV and visible light; in the case of polydomain Liquid-crystalline elastomer films, a single film could be bent repeatedly and precisely along any chosen direction by using linearly polarized light.

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  • Liquid-crystalline elastomers with photomechanical properties

    YL Ya, M Nakano, T Ikeda

    LIQUID CRYSTALS VIII   5518   1 - 10   2004

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    Photoinduced bending and unbending behavior of liquid-crystal line elastomers is discussed. Various modes of bending have been achieved with various alignments of the photoactive mesogens in the elastomers: oriented Liquid-crystalline elastomer films were found to undergo anisotropic bending and unbending behavior only along the rubbing direction, when exposed to alternate irradiation of unpolarized UV and visible light; in the case of polydomain Liquid-crystalline elastomer films, a single film could be bent repeatedly and precisely along any chosen direction by using linearly polarized light.

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  • Photoinduced Reorientation of Liquid Crystals Doped with Thiophene Having Ester Moieties

    M. Yaegashi, A, Shishido T, Shiono T. Ikeda

    Trans. Mater. Res. Soc. Jpn.   29   955 - 958   2004

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  • 高分子アゾベンゼン液晶フィルムのブラッグ型高回折効率ホログラム

    宍戸厚, 池田富樹

    機能材料   24 ( 5 )   5 - 9   2004

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  • 光駆動高分子液晶フィルム-光で自由に曲がるプラスチック-

    池田富樹, 兪燕蕾, 中野誠

    応用物理   73   947 - 951   2004

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  • Photoinduced Reorientation of Liquid Crystals Doped with Thiophene Having Ester Moieties

    M. Yaegashi, A, Shishido T, Shiono T. Ikeda

    Trans. Mater. Res. Soc. Jpn.   29   955 - 958   2004

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  • Polarized emission from self-organized low-molecular-weight liquid crystals with the aid of hole-injecting materials

    M Kawamoto, H Mochizuki, T Ikeda, B Lee, Y Shirota

    JOURNAL OF APPLIED PHYSICS   94 ( 10 )   6442 - 6446   2003.11

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    Electroluminescent (EL) properties of a low-molecular-weight liquid crystal (LC), which is composed of an oxadiazole moiety as an electron-transporting unit and an amine moiety as a hole-transporting unit, were investigated. The most significant characteristic of the LC is to possess bipolar carrier-transporting abilities. The bipolar LC makes it possible to fabricate a simple EL device. We fabricated an EL device (cell gap: 2 mum) with configuration of indium tin oxide (ITO)/LC/MgAg. The device emitted visible light at above 10 V. In particular, the values of luminance and current density of an EL device containing poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT) as a hole-injecting layer were ten and six times higher than those of the ITO/LC/MgAg device without the PEDOT layer, respectively. Furthermore, surfaces of the glass substrate with an ITO electrode and a PEDOT layer were rubbed to align mesogens. Dichroic ratio of the emission from an ITO/rubbed PEDOT/LC/MgAg device was estimated to be 2.8. These results indicate that the origin of polarized emission in the LC phase is the anisotropic arrangement of the mesogenic units. (C) 2003 American Institute of Physics.

    DOI: 10.1063/1.1621726

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  • A novel class of photo- and electroactive polymers containing oxadiazole and amine moieties in a side chain

    H Mochizuki, T Hasui, M Kawamoto, T Ikeda, C Adachi, Y Taniguchi, Y Shirota

    MACROMOLECULES   36 ( 10 )   3457 - 3464   2003.5

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    A new class of photo- and electroactive polymer materials showing an liquid-crystalline (LC) phase were designed and synthesized: four kinds of polymers with both oxadiazole and arylamine moieties as carrier-transporting groups in the side chain. Among them, the polymers with a dimethylamine and a methylcarbazole moiety show LC phases. Furthermore, all the polymers emitted strong blue fluorescence, and their fluorescent quantum yields were over 0.6. The aligned sample of the polymer with the carbazole moiety emitted polarized fluorescence at room temperature. One-layer type electroluminescent (EL) devices were fabricated by using the polymer with a triphenylamine moiety, which exhibited the highest quantum yield (similar to0.82), and found to emit the EL emission at blue region.

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  • Functional materials and electro-optic properties for polymer stabilized ferroelectric liquid crystal

    JH Song, LS Park, ET Seon, YB Kim, T Ikeda

    SYNTHETIC METALS   137 ( 1-3 )   1411 - 1412   2003.4

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    In order to improve the electro-optic properties of polymer stabilized ferroelectric liquid crystal display(PS-FLCD) cells, new functional monomer was synthesized. The PS-FLCD cells were fabricated by UV irradiation with varying monomer doping concentrations. The electro-optic Properties were with examined with respect to cell morphology of cell and response time.

    DOI: 10.1016/S0379-6779(02)01107-4

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  • Facile synthesis of 2,5-diarylthiazoles via palladium-catalyzed tandem C-H substitutions. Design of tunable light emission and liquid crystalline characteristics

    A Mori, A Sekiguchi, K Masui, T Shimada, M Horie, K Osakada, M Kawamoto, T Ikeda

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   125 ( 7 )   1700 - 1701   2003.2

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    DOI: 10.1021/ja0269189

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  • A liquid crystalline polyketone prepared from allene having an azobenzene substituent and carbon monoxide

    Y Takenaka, K Osakada, M Nakano, T Ikeda

    MACROMOLECULES   36 ( 4 )   1414 - 1416   2003.2

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    DOI: 10.1021/ma020958+

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  • Photoinduced alignment of liquid crystals parallel to the polarization direction of linearly polarized light

    CY Xu, T Shiono, T Ikeda, YH Wang, Y Takeuchi

    JOURNAL OF MATERIALS CHEMISTRY   13 ( 4 )   669 - 671   2003

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    The alignment direction of liquid crystals on polyimide alignment films prepared by in situ exposure to linearly polarized light (LPL) during thermal imidization of poly(amic acid)s has been found to be parallel to the direction of polarization of the LPL, whereas the conventional method, in which the alignment layers are exposed to LPL after imidization, leads to alignment perpendicular to the direction of polarization of the LPL.

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  • Holographic image storage in polymer azobenzene liquid crystals

    T Ikeda, S Yoneyama, T Yamamoto, M Hasegawa

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   401   149 - 159   2003

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    Unique characteristics were observed in phase-type gratings which were formed in polymer liquid crystal (PLC) films. We have investigated the formation and the properties of the holographic gratings recorded in PLCs with azobenzene moieties (photoresponsive unit). Two types of PLCs were examined: homopolymers of azobenzene monomers (PALC) and copolymers with a tolane moiety (mesogenic unit with a high birefringence) in the side chain. The diffraction efficiency (it) was enhanced in the LC phase. We obtained the value of eta of 31% while it was less than 1% in a glassy state in the Raman-Nath regime. This difference may be due to the modulation of refractive index (Deltan) based on alignment change of rnesogens in the PLC film. In addition, we attempted the holographic image storage of three-dimensional (3-D) objects in the PLC film. The 3-D object was reconstructed with high resolution (>5, 000 lines /mm).

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  • Facile Synthesis of 2,5-Diarylthiazoles via Palladium-Catalyzed Tandem C-H Substitutions. Design of Tunable Light Emission and Liquid Crystalline Characteristics

    A. Mori, A. Sekiguchi, K, Masui T, Shimada M. Horie, K, Osakada M, Kawamoto, T. Ikeda

    J. Am. Chem. Soc.   125 ( 7 )   1700 - 1701   2003

  • Holographic image storage in polymer azobenzene liquid crystals

    Tomiki Ikeda, Satoshi Yoneyama, Takahiro Yamamoto, Makoto Hasegawa

    Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals   401 ( 2 )   35 - 45   2003

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    Unique characteristics were observed in phase-type gratings which were formed in polymer liquid crystal (PLC) films. We have investigated the formation and the properties of the holographic gratings recorded in PLCs with azobenzene moieties (photoresponsive unit). Two types of PLCs were examined: homopolymers of azobenzene monomers (PALC) and copolymers with a tolane moiety (mesogenic unit with a high birefringence) in the side chain. The diffraction efficiency (η) was enhanced in the LCphase. We obtained the value of η of 31% while it was less than 1% in a glassy state in the Raman-Nath regime. This difference may be due to the modulation of refractive index (Δn) based on alignment change of mesogens in the PLC film. In addition, we attempted the holographic image storage of three-dimensional (3-D) objects in the PLC film. The 3-D object was reconstructed with high resolution (&gt
    5,000 lines/mm).

    DOI: 10.1080/15421400390243165

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  • Highly Efficient Formation of Holographic Gratings in Polymer Liquid Crystals

    K. Okano, A. Shishido, O. Tsutsumi, T. Shiono, T. Ikeda

    Proceedings of SPIE   139   5213 - 5218   2003

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  • Photoinduced alignment of liquid crystals parallel to the polarization direction of linearly polarized light

    CY Xu, T Shiono, T Ikeda, YH Wang, Y Takeuchi

    JOURNAL OF MATERIALS CHEMISTRY   13 ( 4 )   669 - 671   2003

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    The alignment direction of liquid crystals on polyimide alignment films prepared by in situ exposure to linearly polarized light (LPL) during thermal imidization of poly(amic acid)s has been found to be parallel to the direction of polarization of the LPL, whereas the conventional method, in which the alignment layers are exposed to LPL after imidization, leads to alignment perpendicular to the direction of polarization of the LPL.

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  • Side-Chain Polymer Liquid Crystals Containing Oxadiazole and Amine Moieties with Carrier-Transporting Abilities for Single-Layer Light-Emitting Diodes

    M. Kawamoto, H. Mochizuki, A. Shishido O, Tsutsumi T. Ikeda, B. Lee, Y. Shirota

    J. Phys. Chem. B.   107 ( 21 )   4887 - 4893   2003

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  • Photoresponsive behavior of azobenzene liquid-crystalline gels

    M Nakano, YL Yu, A Shishido, O Tsutsumi, A Kanazawa, T Shiono, T Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   398   1 - 9   2003

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    ne azobenzene liquid-crystalline gel (LCG) films with macroscopic uniaxial alignment were prepared to investigate photoresponsive behavior By polarizing microscopy, fiber-like structures aligned in one direction were observed. Furthermore, with a confocal laser scanning microscope (CLSM), it was confirmed that the fiber-like structures were formed even in the bulk of the LCGs. When the LCG films were irradiated with UV light below Tg, changes in the microscopic surface morphology were observed, while no appreciable macroscopic change was observed. On the other hand, when the LCGs were plasticized by suspending in solvents or heating above Tg, the LCG films showed macroscopic changes (e.g. bending) upon UV light irradiation. The bending and unbending could be repeated just by changing the wavelength of the irradiation light. It was suggested that the bending is induced by an absorption gradient which produces a volume difference between the front surface area and the bulk of the gel films.

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  • Photoresponsive behavior of azobenzene liquid-crystalline gels

    M Nakano, YL Yu, A Shishido, O Tsutsumi, A Kanazawa, T Shiono, T Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   398   1 - 9   2003

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    ne azobenzene liquid-crystalline gel (LCG) films with macroscopic uniaxial alignment were prepared to investigate photoresponsive behavior By polarizing microscopy, fiber-like structures aligned in one direction were observed. Furthermore, with a confocal laser scanning microscope (CLSM), it was confirmed that the fiber-like structures were formed even in the bulk of the LCGs. When the LCG films were irradiated with UV light below Tg, changes in the microscopic surface morphology were observed, while no appreciable macroscopic change was observed. On the other hand, when the LCGs were plasticized by suspending in solvents or heating above Tg, the LCG films showed macroscopic changes (e.g. bending) upon UV light irradiation. The bending and unbending could be repeated just by changing the wavelength of the irradiation light. It was suggested that the bending is induced by an absorption gradient which produces a volume difference between the front surface area and the bulk of the gel films.

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  • Side-Chain Polymer Liquid Crystals Containing Oxadiazole and Amine Moieties with Carrier-Transporting Abilities for Single-Layer Light-Emitting Diodes

    M. Kawamoto, H. Mochizuki, A. Shishido O, Tsutsumi T. Ikeda, B. Lee, Y. Shirota

    J. Phys. Chem. B.   107 ( 21 )   4887 - 4893   2003

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  • High-performance material for holographic gratings by means of a photoresponsive polymer liquid crystal containing a tolane moiety with high birefringence

    S Yoneyama, T Yamamoto, O Tsutsumi, A Kanazawa, T Shiono, T Ikeda

    MACROMOLECULES   35 ( 23 )   8751 - 8758   2002.11

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    Formation of intensity gratings was studied with two s-polarized (s+s) writing beams in polymer liquid crystals (PLCs) containing a photochromic moiety (azobenzene) and a mesogenic unit (tolane, T-AB; cyanobiphenyl, CB-AB) by means of photoinduced change in alignment of PLCs. Remarkable differences were observed between these two PLCs. T-AB showed higher values of the diffraction efficiency (eta) and a faster response than CB-AB. In photoinduced alignment behavior of the PLCs, T-AB exhibited a faster change in alignment than CB-AB with the value of eta about 30% in the Raman-Nath regime and the maximum value for modulation of the refractive index (Deltan') of about 0.08. It wag revealed that eta and Deltan' are dependent on the structure of the mesogenic unit. In addition, we attempted the holographic image storage of three-dimensional (3-D) objects in the T-AB films. The 3-D object was reconstructed with high resolution (>5000 lines/mm).

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  • 架橋型ジアミドジメチルチタン錯体-アルミノキサン触媒系によるプロピレンのリビング重合

    萩本 準, 塩野 毅, 池田 富樹

    触媒   44 ( 6 )   429 - 431   2002.9

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  • Copolymerization of 1,3-butadiene and isoprene with cobalt dichloride/methylaluminoxane in the presence of triphenylphosphine

    DCD Nath, T Shiono, T Ikeda

    JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY   40 ( 17 )   3086 - 3092   2002.9

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    The homopolymerization and copolymerization of 1,3-butadiene and isoprene were achieved at 0 degreesC with cobalt dichloride in combination with methylaluminoxane and triphenylphosphine (Ph3P). For 1,3-butadiene, highly cis-specific and 1,2-syndiospecific polymerization proceeded in the absence or presence of Ph3P, respectively, although the activity with Ph3P was much higher than that without Ph3P. Only a trace of the polymer was, however, obtained in isoprene polymerization when Ph3P had been added. For copolymerization, the polymer yield in the presence of Ph3P was about three times higher than that in its absence. Copolymerization in the presence of Ph3P was, therefore, investigated in more detail. Unimodal gel permeation chromatography elution curves with narrower polydispersity (weight-average molecular weight/number-average molecular weight approximate to 1.5) indicated that the propagation reaction proceeded by single-site active species. Both the yield and molecular weight of the copolymer decreased with an increasing amount of isoprene in the feed, and this was followed by an increase in the isoprene content in the copolymer. The monomer reactivity ratios, r(1) (1,3-butadiene) and r(2) (isoprene), were estimated to be 2.8 and 0.15, respectively. Although the 1,3-butadiene content in the copolymer was strongly dependent on the comonomer composition in the feed, the ratio of 1,2-inserted units to 1,4-inserted units of 1,3-butadiene was constant. Concerning the isoprene unit, the percentage of 1,2- and 3,4-inserted units was increased at the expense of 1,4-inserted units with an increasing isoprene content in the feed. (C) 2002 Wiley Periodicals, Inc.

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  • Propene polymerization with stereospecific metallocene dichloride-[Ph3C][B(C6F5)(4)] using omega-alkenylaluminum as an alkylation reagent and as a functional comonomer

    YG Nam, T Shiono, T Ikeda

    MACROMOLECULES   35 ( 18 )   6760 - 6762   2002.8

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    DOI: 10.1021/ma025528y

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  • Living polymerization of propene with a chelating (diamide)dimethyltitanium complex using silica-supported methylaluminoxane

    H Hagimoto, T Shiono, T Ikeda

    MACROMOLECULES   35 ( 15 )   5744 - 5745   2002.7

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    DOI: 10.1021/ma025535m

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  • Effects of halogen ligands on 1,3-butadiene polymerization with cobalt dihalides and methylaluminoxane

    DCD Nath, T Shiono, T Ikeda

    MACROMOLECULAR CHEMISTRY AND PHYSICS   203 ( 9 )   1171 - 1177   2002.6

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    We conducted 1,3-butadiene polymerization at 0 and 18degreesC using CoX2 (X = halogen) combined with MAO to elucidate the role of halogen ligands attached to cobalt. With increasing the polymerization time, the molecular weight distribution curves of the polymers obtained progressively shifter to higher molecular weight regions accompanied by narrowing polydispersity irrespective of the cobalt halides emplyed. The polymer yield linearly increased after an exponential induction stage, while the number-average molecular weight linearly increased vs. polymerization time. Thus, the number of polymer chains calculated from the polymer yield and the number average molecular weight increased with polymerization time. After a certain polymerization time, the number of polymer chains was saturated to be about 60% catalyst efficiency in the CoCl2 and CoBr2 systems but only about 2% in the CoI2 system. The number average molecular weight increases linearly vs. polymer yield from a small positive intercept. these phenomena were interpreted by a slow initiation system without any termination and chain transfer reaction. The kinetic analysis indicated that the rates of initiation were significantly influenced by the nature of the halides and descended in the following order CoCl2 > CoBr2 > CoI2 > CoF2 = 0, whereas the rates of propagation were independent on variation of halogen ligands. H-1 and C-13 NMR analyses of the polymers indicated that the microstructure of the resulting polymer was high cis-1,4 irrespective of the halogen ligands.

    DOI: 10.1002/1521-3935(200206)203:9<1171::AID-MACP1171>3.0.CO;2-U

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  • Propagation Mechanism for Living Polymerization of Olefins Using [t-BuNSiMe2Flu]TiMe2–Based Catalysts Reviewed

    西井 圭, 塩野毅, 池田富樹

    高分子論文集, 59巻, pp.371-376   2002.6

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  • Photoinduced reorientation and thermal effects in an oligothiophene-doped liquid crystal system

    HC Zhang, S Shiino, A Kanazawa, O Tsutsumi, T Shiono, T Ikeda

    JOURNAL OF APPLIED PHYSICS   91 ( 9 )   5558 - 5563   2002.5

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    Photoinduced reorientation (photon-mode process) and thermal effects in an oligothiophene-doped liquid crystal (LC) system were investigated by self-diffraction measurements in different experimental configurations. The results obtained in homeotropic sample cells were compared with those obtained in homogeneous cells. Optical Freedericksz transition could be induced by low-intensity light in the homeotropic cell, and the induced birefringence was affected by the thermal effect. No photoinduced reorientation effect was observed in the homogeneous cell in the present experimental configuration; however, due to the thermal modulation of the refractive index of the LC, which arises from light absorption, self-diffraction phenomena could also be observed. (C) 2002 American Institute of Physics.

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  • (tert-ブチルアミドジメチルシリルフルオレニル)ジメチルチタン触媒系によるオレフィンリビング重合の成長反応機能 Reviewed

    西井圭, 塩野, 毅, 池田富樹

    高分子論文集   59 ( 6 )   371 - 376   2002.4

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  • Optically switchable liquid crystals containing azobenzene chromophores.

    T Ikeda, A Shishido, O Tsutsumi, A Kanazawa

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   223   D47 - D48   2002.4

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  • cis-specific living polymerization of 1,3-butadiene with CoCl2 and methylaluminoxane

    DCD Nath, T Shiono, T Ikeda

    MACROMOLECULAR CHEMISTRY AND PHYSICS   203 ( 4 )   756 - 760   2002.3

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    The polymerization of 1,3-butadiene was conducted by CoCl2 combined with methylaluminoxane (MAO) as a cocatalyst at 0 and 18degreesC. The uni-modal molecular weight distribution curves of the resulting polymers shifted toward higher molecular weight regions and became narrower when increasing the polymerization time. The number-average molecular weight increased linearly with polymerization time, while the polymer yield increased exponentially in the initial stage. As a consequence, the number of polymer chains, calculated from the polymer yield and (M) over bar (n), increased gradually with polymerization time to reach a plateau value. These phenomena was interpreted based on a slow initiation system without any termination and chain transfer reaction. The microstructure of the polymer was determined by H-1 NMR and C-13 NMR spectroscopy to be a cis-1,4 structure in a 98-99% purity.

    DOI: 10.1002/1521-3935(20020301)203:4<756::AID-MACP756>3.0.CO;2-K

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  • Effects of cocatalysts on propene polymerization with [t-BuNSiMe2(CSMe4)]TiMe2

    A Ioku, T Hasan, T Shiono, T Ikeda

    MACROMOLECULAR CHEMISTRY AND PHYSICS   203 ( 4 )   748 - 755   2002.3

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    Propene polymerization was conducted using [t-BuNSiMe2(C5Me4)]TiMe2 combined with various cocatalysts at 0degreesC, and kinetic profiles were investigated under atmospheric pressure of propene in a semibatch system. Dried methylaluminoxane (MAO), which was free of Me3Al, was found to be more active than the standard MAO system, resulting in a steady polymerization rate and giving higher molecular-weight polypropenes. Sampling experiments during the polymerization showed an almost linear relationship between the number-average molecular weight, (M) over bar (n), and polymerization time while retaining a narrow molecular-weight distribution, whereas the results of batch polymerization with different monomer concentrations and post-polymerization indicated that chain transfer reactions occurred to a minor degree under these polymerization conditions. Additive effects of trialkylaluminium on the dried MAO system showed that the polymer yield was increased by the addition of i-Bu3Al and Oct(3)Al and decreased by Me3Al and Et3Al. All of the trialkylaluminium compounds increased the number of polymer chains (N), and the Et3Al system showed the highest N value with the lowest (M) over bar (n) value.

    DOI: 10.1002/1521-3935(20020301)203:4<748::AID-MACP748>3.0.CO;2-G

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  • Supporting effect of methylaluminoxane on propene polymerization with monocyclopentadienylalkyltitanium derivatives

    A Ioku, T Shiono, T Ikeda

    APPLIED CATALYSIS A-GENERAL   226 ( 1-2 )   15 - 22   2002.2

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    Propene polymerization was carried out by Cp*Ti(CH2Ph)(3), [t-BuNSiMe2(C5Me4)]TiMe2 and [t-BuNSiMe(2)Flu]TiMe2 combined with dried Or SiO2-supported methylaluminoxane (MAO). The dried MAO system generally showed higher activity and gave higher molecular weight polypropenes than the SiO2-supported MAO system. The decrease in the activity by changing the cocatalyst from dried MAO to SiO2-supported MAO was, however, more significant in the cases of [t-BuNSiMe2(C5Me4)]TiMe2 and [t-BuNSiMe(2)Flu]TiMe2. The molecular weight distribution of the produced polymers indicated that uniform active species were formed from Cp*Ti(CH2Ph)(3) regardless of the cocatalyst employed while the active species derived from [t-BuNSiMe2(C5Me4)]TiMe2 and [t-BuNSiMe(2)Flu]TiMe2 combined with SiO2-supported MAO were inhomogencous. The microstructure of the produced polymers were independent of the cocatalyst used, and [t-BuNSiMe(2)Flu]TiMe2 catalysts produced syndiotactic polypropenes with less regioirregular structure. The Cp*Ti(CH2Ph)(3)/SiO2-supported MAO system showed a steady polymerization rate with frequent chain transfer at 0degreesC while the [t-BuNSiMe2(C5Me4)]TiMe2/SiO2-supported MAO system produced the polypropenes with long chain lifetime accompanied by slow deactivation at 0degreesC. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0926-860X(01)00873-0

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  • Living polymerization of propene with a chelating diamide complex of titanium using dried methylaluminoxane

    H Hagimoto, T Shiono, T Ikeda

    MACROMOLECULAR RAPID COMMUNICATIONS   23 ( 1 )   73 - 76   2002.1

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    The living polymerization of propene was conducted at 0degreesC using a chelating diamide complex of titanium combined with dried modified methylaluminoxane from which free trialkylaluminium compounds were removed much as possible before use. The number-average molecular weight of the statistically poly(propylene) produced increased almost linearly with increasing polymerization time accompanied by a narrowing of the molecular weight distribution from 1.34 to 1.16.

    DOI: 10.1002/1521-3927(20020101)23:1<73::AID-MARC73>3.0.CO;2-Q

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  • X-ray measurements of an oligothiophene containing acetylene linkage

    HC Zhang, S Shiino, A Kanazawa, O Tsutsumi, T Shiono, T Ikeda, Y Nagasel

    SYNTHETIC METALS   126 ( 1 )   11 - 18   2002.1

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    We synthesized a mesogenic oligothiophene, 5,5"-bis(5-butyl-2-tienylethyntyl)-2,2':5',2"-terthiophene (TR5), which contains acetylene linkage. Nematic and monotropic smectic phases were observed. Molecular packing of TR5 in crystal and liquid crystal phases was studied by X-ray measurements. It was found that the three central thiophenes of the TR5 molecule were coplanar, while the two terminal-thiophenes form dihedral angles of 58-61degrees with respect to the central thiophene. We attribute the unplanar molecular conformation of TR5 to the existence of triple bonds between thiophenes, which may change the intramolecular interaction in pi-conjugation systems considerably. The average intermolecular distance of TR5 was determined to be 4.6 Angstrom in the nematic phase. The interlayer spacing of the smectic phase was found to be almost the same as the molecular length of TR5 and we attributed this phase as a smectic B. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0379-6779(01)00486-6

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  • X-ray measurements of an oligothiophene containing acetylene linkage

    HC Zhang, S Shiino, A Kanazawa, O Tsutsumi, T Shiono, T Ikeda, Y Nagasel

    SYNTHETIC METALS   126 ( 1 )   11 - 18   2002.1

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    We synthesized a mesogenic oligothiophene, 5,5"-bis(5-butyl-2-tienylethyntyl)-2,2':5',2"-terthiophene (TR5), which contains acetylene linkage. Nematic and monotropic smectic phases were observed. Molecular packing of TR5 in crystal and liquid crystal phases was studied by X-ray measurements. It was found that the three central thiophenes of the TR5 molecule were coplanar, while the two terminal-thiophenes form dihedral angles of 58-61degrees with respect to the central thiophene. We attribute the unplanar molecular conformation of TR5 to the existence of triple bonds between thiophenes, which may change the intramolecular interaction in pi-conjugation systems considerably. The average intermolecular distance of TR5 was determined to be 4.6 Angstrom in the nematic phase. The interlayer spacing of the smectic phase was found to be almost the same as the molecular length of TR5 and we attributed this phase as a smectic B. (C) 2002 Elsevier Science B.V. All rights reserved.

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  • Dynamics of photochemical phase transition of guest/host liquid crystals with an azobenzene derivative as a photoresponsive chromophore

    JH Sung, S Hirano, O Tsutsumi, A Kanazawa, T Shiono, T Ikeda

    CHEMISTRY OF MATERIALS   14 ( 1 )   385 - 391   2002.1

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    The dynamics of the photochemical phase transition process of guest/host liquid crystals (LCs) containing an azobenzene derivative as a photosensitive chromophore was studied. We proposed a model for the photochemical phase transition of the guest/host LCs and simulated the change in transmittance through LCs due to the phase transition on the basis of this model. Upon irradiation at 366 nm, the cis isomer was generated randomly in the irradiated site, and then the transmittance of the probe light was slightly decreased because of the disturbance of the alignment of the nematic (N) phase by the cis isomers. Upon further irradiation, the N-to-isotropic (I) phase transition took place in local domains, and the transmittance of the probe light decreased with the growth of these local I domains. In the simulations, three factors were found to affect significantly the dynamics of the photochemical phase transition and the change in transmittance of light: the number of I domains formed by irradiation, the growth rate of the I domains, and the threshold size of the I domains detected with the probe light.

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  • Control of regiospecificity in propene polymerization with SiO2-supported Cp*TiMe3 catalysts

    A Ioku, T Shiono, T Ikeda

    JOURNAL OF MACROMOLECULAR SCIENCE-PURE AND APPLIED CHEMISTRY   39 ( 5 )   397 - 404   2002

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    DOI: 10.1081/MA-120003962

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  • Refractive-index modulation by means of photosensitive liquid crystals

    T Ikeda, S Yoneyama, T Yamamoto, M Hasegawa

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   375   45 - 60   2002

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    Liquid crystals (LCs) show an anisotropic nature in various aspects of optical and electronic properties. This anisotropy enables LC materials to be used as active media in display devices. Birefringence, an anisotropy in optical properties of LCs, is especially useful from the viewpoint of the change in refractive index induced by light. This is the principle of LC photonics, in which optical signals are processed with the aid of LC materials. In this article, various approaches are described to change the alignment of the LC molecules: 1) photochemically induced phase transition of LCs by photochromic reactions is an order to disorder transition and can be brought about in a time scale of micro- to nanosecond; 2) reorientation of LC molecules by means of linearly polarized light is a change in alignment of LC molecules that occurs within the LC phase-, and induces a large change in refractive index, but needs more time. Applications of LC systems as holographic materials are discussed.

    DOI: 10.1080/10587250210580

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  • Refractive-index modulation by means of photosensitive liquid crystals

    T Ikeda, S Yoneyama, T Yamamoto, M Hasegawa

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   375   45 - 60   2002

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    Liquid crystals (LCs) show an anisotropic nature in various aspects of optical and electronic properties. This anisotropy enables LC materials to be used as active media in display devices. Birefringence, an anisotropy in optical properties of LCs, is especially useful from the viewpoint of the change in refractive index induced by light. This is the principle of LC photonics, in which optical signals are processed with the aid of LC materials. In this article, various approaches are described to change the alignment of the LC molecules: 1) photochemically induced phase transition of LCs by photochromic reactions is an order to disorder transition and can be brought about in a time scale of micro- to nanosecond; 2) reorientation of LC molecules by means of linearly polarized light is a change in alignment of LC molecules that occurs within the LC phase-, and induces a large change in refractive index, but needs more time. Applications of LC systems as holographic materials are discussed.

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  • A rodlike organogelator: fibrous aggregation of azobenzene derivatives with a syn-chiral carbonate moiety

    J Mamiya, K Kanie, T Hiyama, T Ikeda, T Kato

    CHEMICAL COMMUNICATIONS   ( 17 )   1870 - 1871   2002

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    A chiral azobenzene derivative containing a cyclic syncarbonate moiety functions as a gelator for various organic solvents; the dipole-dipole interaction drives the fibrous self-assembly of the rodlike gelator.

    DOI: 10.1039/b205072b

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  • Polymer azobenzene liquid crystal films with nano-second photoresponse.

    Kanato Adachi, Atsushi Shishido, Osamu Tsutsumi, Tomiki Ikeda

    KOBUNSHI RONBUNSHU   59   767-771   2002

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  • Supporting Effect of Methylaluminoxane with Monocylcopentadienylalkyltitanium Derivatives on Propene Polymerization

    A. Ioku T, Shiono T. Ikeda

    Appl. Catal. A: General   226   15 - 22   2002

  • Propagation mechanism for living polymerization of olefins using [eta(1):eta(3)-tert-Butyl(dimethylfluorenylsilyl)amido] dimethyltitanium-based catalyst Reviewed

    K Nishii, T Shiono, T Ikeda

    KOBUNSHI RONBUNSHU   59 ( 6 )   371 - 376   2002

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    Language:Japanese   Publisher:SOC POLYMER SCIENCE JAPAN  

    1-Octene polymerization was conducted by [eta(1): eta(3)-tert-butyl(dimethylfluorenyisilyl)amido]dimethyltitanium ([t-BuNSiMe(2)Flu]TiMe2) activated with tris(pentafluorophenyl)borane (B(C6F5)(3)) at -50degreesC in the presence of trioctylaluminium (Oct(3)Al). The polymer yield linearly increased with increasing polymerization time. The poly(1-octene) obtained showed narrow molecular weight distributions (M-w/M-n) of about 1.1. In addition, the number average molecular weight (4) of the polymer was proportional to the polymer yield. These results indicated that living polymerization of I-octene proceeded with this catalyst system. The dependence of propagation rate on 1-octene concentration was investigated under various 1-octene concentrations in the polymerization of low conversion (&lt;10%). The M-n values at a certain polymerization time were independent of 1-octene concentrations, which indicated that the Propagation rate was almost zeroth order in 1-octene. Polymerization of 1-butene and 1-hexene with this catalyst system also proceeded in a living manner. and their propagation rates were also independent of monomer concentration. 1-Octene polymerization was conducted by this catalyst system with various concentrations of B(C6F5)(3). The polymer yield and Mn value did not depend on the B(C6F5)(3)]/[Ti] ratio and the polymers with narrow Mw/Mn were obtained. The results indicated that the propagation rate was not affected by excess B(C6F5)(3).

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  • 光による分子配列の形成と制御

    宍戸厚, 池田富樹

    O plus E   24   269 - 274   2002

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  • Chemospecificity in arylations of delta- and gamma-ketocarboxylic acids with P2O5-MsOH, TfOH, and related acidic media

    N Yonezawa, M Koike, A Kameda, S Naito, T Hino, K Maeyama, T Ikeda

    SYNTHETIC COMMUNICATIONS   32 ( 20 )   3169 - 3180   2002

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    Remarkable contrast between chemospecificities in acid-mediated arylation of delta- and gamma-ketocarboxylic acids was revealed: in the presence of P2O5-MsOH, TfOH, PPA, and MsOH, arylation of delta-ketocarboxylic acid 1A with arenes takes place at the carboxycarbonyl carbon, while that of gamma-ketocarboxylic acid 1B takes place at the ketone carbonyl carbon, specifically.

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  • Control of regiospecificity in propene polymerization with SiO2-supported Cp*TiMe3 catalysts

    A Ioku, T Shiono, T Ikeda

    JOURNAL OF MACROMOLECULAR SCIENCE-PURE AND APPLIED CHEMISTRY   39 ( 5 )   397 - 404   2002

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    DOI: 10.1081/MA-120003962

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  • Ethyl cellulose films as alignment layers for liquid crystals

    LF Yan, QS Zhu, T Ikeda

    JOURNAL OF APPLIED POLYMER SCIENCE   82 ( 11 )   2770 - 2774   2001.12

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    Films were formed by coating hydroxypropyl cellulose (HPC) or ethyl cellulose (EC) with different kinds of solvents at high coating speeds and thin coating thicknesses. These films were used as alignment layers for liquid crystals. Atomic force microscopy (AFM) and polarizing optical microscopy (POM) were used to identify the banded texture structure of the films. The alignments of a nematic liquid crystal 5CB droplet on those films were observed by POM. Further, a novel cycle disclination line was recorded and studied. (C) 2001 John Wiley & Sons, Inc.

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  • Distinct thermodynamic behaviour of a mesomorphic gold nanoparticle covered with a liquid-crystalline compound

    N Kanayama, O Tsutsumi, A Kanazawa, T Ikeda

    CHEMICAL COMMUNICATIONS   ( 24 )   2640 - 2641   2001.12

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    Gold nanoparticles covered with a liquid-crystalline compound were successfully prepared, exhibiting characteristic double-melting behaviour.

    DOI: 10.1039/b108909a

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  • Copolymerization of propene and 1,2,4-trivinylcyclohexane by a MgCl2-supported TiCl4 catalyst

    YG Nam, S Murayama, T Shiono, T Ikeda

    MACROMOLECULES   34 ( 19 )   6533 - 6535   2001.9

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    DOI: 10.1021/ma010465p

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  • Syndio-specific living polymerization of propene with [t-BuNSiMe(2)Flu]TiMe2 using MAO as cocatalyst. (vol 34, pg 3142, 200)

    T Hasan, A Ioku, K Nishii, T Shiono, T Ikeda

    MACROMOLECULES   34 ( 17 )   6152 - 6152   2001.8

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    DOI: 10.1021/ma0017438

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  • Optical recording using a photochromic ferroelectric liquid crystal

    L. Komitov, O. Tsutsumi, C. Ruslim, T. Ikeda, K. Ichimura, K. Yoshino

    Journal of Applied Physics   89 ( 12 )   7745 - 7749   2001.6

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    The direction of molecular switching, i.e., the sign of the electro-optic response, in ferroelectric liquid crystals depends on the polarity of the applied electric field as well as on the sign of the spontaneous polarization. Light-induced switching of the molecules by ultraviolet light was found in a photochromic ferroelectric liquid crystal at fixed field polarity. A high contrast image was recorded whose contrast could easily be inverted by reversing the field polarity. Moreover, in the presence of bistable boundary conditions, the optically recorded image can be stored after removal of the electric field. The effect of light-assisted switching in the photochromic ferroelectric liquid crystal seems to be promising for applications such as optical recording, all-optical switches, and image storage. © 2001 American Institute of Physics.

    DOI: 10.1063/1.1373697

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  • Living copolymerization of propene and alpha-olefins with Me2Si(eta(3)-Flu)((BuN)-Bu-t)TiMe2-based catalysts.

    T Shiono, A Kanetaka, N Kei, T Ikeda

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   221   U368 - U368   2001.4

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  • Phase-type gratings formed by photochemical phase transition of polymer azobenzene liquid crystal. 2. Rapid switching of diffraction beams in thin films

    T Yamamoto, A Ohashi, S Yoneyama, M Hasegawa, O Tsutsumi, A Kanazawa, T Shiono, T Ikeda

    JOURNAL OF PHYSICAL CHEMISTRY B   105 ( 12 )   2308 - 2313   2001.3

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    Dynamic holographic gratings were investigated with thin films of polymer azobenzene liquid crystals by periodic induction of photochemical nematic-to-isotropic phase transition. On irradiation of writing beams (488 nm), multiple diffraction beams of a reading beam (633 nm) were immediately observed. The first-order diffraction efficiency reached to a maximum value within several tens of milliseconds: the rise time was approximately 50 ms for PM6AB2 films and 30 ms for PA6ABCN films. Quite large modulation in refractive index (similar to0.08) was obtained in both polymer films. Studies on effects of temperature and light intensity on the grating formation suggested that photochemical reactions of azobenzene moieties followed by photochemical phase transition in bright fringes of the interference pattern would be responsible for the formation of holographic gratings. By turning on and off the writing beams, the diffraction beams could be switched dynamically without significant fatigue.

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  • Novel cross-linked organic materials with pronounced spontaneous polarization based on bis-dipolar molecules

    CD Keum, A Kanazawa, T Ikeda

    ADVANCED MATERIALS   13 ( 5 )   321 - 323   2001.3

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    DOI: 10.1002/1521-4095(200103)13:5<321::AID-ADMA321>3.0.CO;2-4

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  • Thermal stability of alignment of a nematic liquid crystal induced by polyimides exposed to linearly polarized light

    YH Wang, CY Xu, A Kanazawa, T Shiono, T Ikeda, Y Matsuki, Y Takeuchi

    LIQUID CRYSTALS   28 ( 3 )   473 - 475   2001.3

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    The thermal stability of alignment of a nematic liquid crystal (LC) on three polyimide (PI) films exposed to linearly polarized light at 366 nm was investigated. Polarizing optical microscopy analysis indicates that the thermal stability of the LC alignment on the PI film without significant structural change was higher than that with obvious structural change.

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  • Supramolecular polar thin films built by surfactant liquid crystals: Polarization-tunable multilayer self-assemblies with in-plane ferroelectric ordering of ion-based dipoles

    A Kanazawa, T Ikeda, J Abe

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   123 ( 8 )   1748 - 1754   2001.2

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    Polar order in the phosphonium liquid crystal thin films, which are composed of two-dimensional ion-pair-based domains separated by the insulating hydrocarbon layers, was probed by second harmonic generation (SHG) analysis. Despite the ordinary amphiphilic self-assemblies containing no pi -electron moieties, the solid-state thin films retaining a smectic layer structure showed clearly an SHG activity, while the disordered films without the layer structure were not active at all for the SHG. It was found that the multilayer structure plays a crucial role for the SHG from the phosphonium thin films and the ionic layers act as an SHG-active site. The most significant characteristic of this system is to possess an ability to control SHG intensity electrically. The efficiency of the SHG process in the thin-film assemblies was enhanced by applying an external electric field parallel to the layer plane. Furthermore, through evaluation of thermal stability of the sample films, it was revealed that the SHG signals were detected only in the solid-state temperature range and the disappearance of the SHG occurs earlier than the solid-to-liquid crystalline phase transition. These results demonstrated that the origin of polar order in the phosphonium thin films is due to in-plane noncentrosymmetric arrangement (ferroelectric ordering) of ion pairs as an electric dipole, that is, dipole symmetry in an ionic layer.

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  • Application of photosensitive polyimides as alignment layer to optical switching devices of a nematic liquid crystal

    GH Kim, S Enomoto, A Kanazawa, T Shiono, T Ikeda, LS Park

    LIQUID CRYSTALS   28 ( 2 )   271 - 277   2001.2

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    We have explored the change in alignment of a nematic liquid crystal, 4'-pentyl-4-cyanobiphenyl (5CB) with three types of photosensitive polyimide as the alignment layer by photoirradiation at 366 nm. The photosensitive polyimide alignment layer induced a reversible change in alignment of 5CB. It was observed that the 5CB molecules became aligned from homogeneous alignment to homeotropic on photoirradiation with a d.c. electric field as a bias, and reversed to the homogeneous state when photoirradiation was ceased. This result indicates that optical switching could be repeated by on and off switching of the excitation light at 366 nm. The optical switching of the nematic liquid crystal might be mainly due to a photophysical change in the polyimide surface which is affected by the chemical structures of the polyimides at the temperature at which 5CB exhibits a nematic phase. The optical switching of nematic liquid crystals with photosensitive polyimides as the alignment layer is a novel driving method for nematic liquid crystals.

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  • Electroluminescent behavior of oxadiazole derivatives in liquid-crystalline media

    H Mochizuki, T Hasui, O Tsutsumi, A Kanazawa, T Shiono, T Ikeda, C Adachi, Y Taniguchi, Y Shirota

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   365   1085 - 1094   2001

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    Electroluminescent (EL) emission has been investigated in a system which consisted of molecular dispersion of 1,4-bis(N,N-diphenylaminophenyl-1,3,4-oxadiazolyl)benzene (OXD) in a liquid crystal, 4-octyloxy-4'-cyanobiphenyl (8OCB). EL emission was observed above the temperature where the OXD/8OCB mixture exhibited a liquid-crystalline phase. In addition, we fabricated and evaluated emission of an EL device which consisted of interdigital electrodes coated onto a glass plate.

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  • Photoinduced reorientation of liquid crystals doped with a mesogenic oligothiophene

    HC Zhang, S Shiino, O Tsutsumi, A Kanazawa, T Shiono, T Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   368   4137 - 4144   2001

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    We studied the dynamic behavior of director-reorientation induced by linearly polarized light in an oligothiophene-doped liquid crystal (LC) by transmission-mode analyses and the Z-scan measurement. An in-plane reorientation process occurred and LC molecules tended to reorient parallel to the polarization of incident light in the case of low-intensity irradiation. The thermal effect due to absorption affects the reorientation behavior largely in the case of high-intensity irradiation.

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  • Ethyl Cellulose Layers as Alignment for Liquid Crystals

    L. Yan, Q. Zhu T. Ikeda

    J. Appl. Polym. Sci.   82 ( 11 )   2770 - 2774   2001

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  • Distinct Thermodynamic Behaviour of A Mesomorfphic Gold Nanoparticle Covered With A Liquid-Crystalline Compound

    N.Kanayama, O.Tsutsumi, A.Kanazawa, T.Ikeda

    Chem.Commun.   ( 24 )   2640 - 2641   2001

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  • Holographic grating by means of polymer liquid crystals

    Tomiki Ikeda, Satoshi Yoneyama, Takahiro Yamamoto, Makoto Hasegawa

    Journal of Information Display   2 ( 3 )   6 - 12   2001

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    Formation of intensity gratings was studied with two s-polarized (s+s) configuration in polymer liquid crystals (PLCs) containing a photochromic moiety (azobenzene) and a mesogenic unit (tolane, T-AB
    cyanobiphenyl, CB-AB) by photoinduced alignment of PLCs. Remarkable differences were observed between the two PLCs. T-AB showed a faster response to the change in the diffraction intensity than CB-AB. In T-AB, alignment change took place faster than that of CB-AB. By introducing the tolane unit at the side chain, we obtained a diffraction efficiency of 30 % in the Raman-Nath regime. © 2001 Taylor &amp
    Francis Group, LLC.

    DOI: 10.1080/15980316.2001.9651860

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  • Formation of Grating by Means of Photoinduced Alignment Changeof Polymer Liquid Crystals with Azobenzene Moieties

    S.Yoneyama, O.Tsutsumi, A.Kanazawa, T.Shiono, T.Ikeda

    Mol.Cryst.Liq.Cryst.   368   335 - 343   2001

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  • Spontaneous Formation of Two-dimensional Self-assembled Polar Atomic Layers with Ferroelectric Ordering of Ion Pairs in Liquid-crystalline Surfctant Complexes

    A.Kanazawa, T.Ikeda

    Mol.Cryst.Liq.Cryst.   366   473 - 482   2001

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  • Rapid photochemical control of phase structure of polymer liquid crystals with hydroxyazobenzene as a photosensitive chromophore

    Osamu Tsutsumi, Tomiki Ikeda

    Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals   368   411 - 422   2001

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    Photochemical phase transition of polymer liquid crystals (LCs) with hydoxyazobenzene moieties has been studied. By irradiation with the laser pulse at 355 nm, photochemical LC-isotropic (I) phase transition of the polymer LCs was induced in microsecond timescale. When the irradiated sample was kept in the dark, the initial LC phase recovered thermally. The response time of the I-LC phase transition was 300 ms in hydoxyazobenzene LCs, while it was 1.5 s in O-alkyl analogues. In the cis-trans isomerization process in hydroxyazobenzenes, the hydrazone was produced by proton transfer, and this tautomer is converted into trans-azobenzenes. In the thermal cis-trans isomerization, hydroxyazobenzenes prefer this two-step mechanism to the one-step mechanism because the activation energy of this mechanism is lower than that of the one-step mechanism. Thus, the thermal isomerization occurred effectively, and the recovery of the LC phase took place quickly in the present polymer LC system. The results obtained here suggest an approach to accelerate the thermal recovery of the LC phase. © 2001 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint, a member of the Taylor &amp
    Francis Group,.

    DOI: 10.1080/10587250108029972

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  • Rapid photochemical control of phase structure of polymer liquid crystals with hydroxyazobenzene as a photosensitive chromophore

    O Tsutsumi, T Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   368   4179 - 4190   2001

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    Photochemical phase transition of polymer liquid crystals (LCs) with hydoxyazobenzene moieties has been studied. By irradiation with the laser pulse at 355 nm, photochemical LC-isotropic (I) phase transition of the polymer LCs was induced in microsecond timescale. When the irradiated sample was kept in the dark, the initial LC phase recovered thermally. The response time of the I-LC phase transition was 300 Pas in hydoxyazobenzene LCs, while it was 1.5 s in O-alkyl analogues. In the cis-trans isomerization process in hydroxyazobenzenes, the hydrazone was produced by proton transfer, and this tautomer is converted into trans-azobenzenes. In the thermal cis-trans isomerization, hydroxyazobenzenes prefer this two-step mechanism to the one-step mechanism because the activation energy of this mechanism is lower than that of the one-step mechanism. Thus, the thermal isomerization occurred effectively, and the recovery of the LC phase took place quickly in the present polymer LC system. The results obtained here suggest an approach to accelerate the thermal recovery of the LC phase.

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  • Electroluminescent behavior of oxadiazole derivatives in liquid-crystalline media

    H Mochizuki, T Hasui, O Tsutsumi, A Kanazawa, T Shiono, T Ikeda, C Adachi, Y Taniguchi, Y Shirota

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   365   1085 - 1094   2001

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    Electroluminescent (EL) emission has been investigated in a system which consisted of molecular dispersion of 1,4-bis(N,N-diphenylaminophenyl-1,3,4-oxadiazolyl)benzene (OXD) in a liquid crystal, 4-octyloxy-4'-cyanobiphenyl (8OCB). EL emission was observed above the temperature where the OXD/8OCB mixture exhibited a liquid-crystalline phase. In addition, we fabricated and evaluated emission of an EL device which consisted of interdigital electrodes coated onto a glass plate.

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  • Photoinduced reorientation of liquid crystals doped with a mesogenic oligothiophene

    HC Zhang, S Shiino, O Tsutsumi, A Kanazawa, T Shiono, T Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   368   4137 - 4144   2001

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    We studied the dynamic behavior of director-reorientation induced by linearly polarized light in an oligothiophene-doped liquid crystal (LC) by transmission-mode analyses and the Z-scan measurement. An in-plane reorientation process occurred and LC molecules tended to reorient parallel to the polarization of incident light in the case of low-intensity irradiation. The thermal effect due to absorption affects the reorientation behavior largely in the case of high-intensity irradiation.

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  • Holographic Grating by Means of Polymer Liquid Crystals

    T. Ikeda, S. Yoneyama T. Yamamoto, M. Hasegawa

    J. Inform. Disp.   2   6 - 12   2001

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  • Photochemical Modulation of Refractive Index by Means of Photosensitive Liquid Crystals

    T.Ikeda

    Mol.Cryst.Liq.Cryst.   364   187 - 197   2001

  • Formation of grating by means of photoinduced alignment change of polymer liquid crystals with azobenzene moieties

    Satoshi Yoneyama, Osamu Tsutsumi, Akihiko Kanazawa, Takeshi Shiono, Tomiki Ikeda

    Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals   368   335 - 343   2001

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    We prepared a polymer liquid crystal (PLC) with ortho-substituted azobenzene to explore the effect of the structure of the photochromic unit on the formation of holographic grating. On this behavior, a remarkable difference was observed between two materials. Grating formation of the ortho-substituted azobenzene moiety proceeded faster than that of common azobenzene analogs without substituents at the ortha position. This result is explained in terms of the stability of the LC phase structure. We investigated the relationship between alignment behavior and change of the diffracted light intensity. The result shows that in the ortho-substituted azobenzene sample, the diffraction efficiency showed maximum when orientational relaxation is completed in a bright area of the interference pattern. © 2001 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint, a member of the Taylor &amp
    Francis Group,.

    DOI: 10.1080/10587250108029963

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  • Spontaneous formation of two-dimensional self-assembled polar atomic layers with ferroelectric ordering of ion pairs in liquid-crystalline surfactant complexes

    A Kanazawa, T Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   366   2325 - 2334   2001

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    The unique optoclectric feature of structurally simple surfactants was presented. Phosphonium salts as a novel class of thermotropic liquid crystals were used to explore the spatial arrangement of ions in multilayer self-assemblies based on the surfactant complexes. Through the evaluation of second-order nonlinear optical property of the phosphonium self-assemblies, it was revealed that the phosphonium thin film assemblies can be regarded as a polar thin film consisting of two-dimensional ionic layers with noncentrosymmetric atomic arrangement. Such spontaneous formation of the in-plane polar structure was assumed to originate from the variety of bonding manner (i.e., the characteristic electronic structure) of phosphorus atom. Furthermore, it was also found that the macroscopic polar order is enhanced by application of an external electric field.

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  • Supramolecular Polar Thin Films Built by Surfactant Liquid Crystals: Polarization-Tunable Multilayer Self-Assemblies with In-Plane Ferroelectric Ordering of Ion-Based Dipoles

    A. Kanazawa, T. Ikeda, J. Abe

    J. Am. Chem. Soc.   123 ( 8 )   1748 - 1754   2001

  • Syndiospecific Living Polymerization of Propene with [t-BuNSiMe2Flu]TiMe2 Using MAO as Cocatalyst

    T. Hasan, A. Ioku, K, Nishii T, Shiono T. Ikeda

    Macromolecules   34 ( 10 )   3142 - 3145   2001

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  • Phase-Type Gratings Formed by Photochemical Phase Transition of Polymer Azobenzene Liquid Crystals: 2. Rapid Switching of Diffraction Beams in This Films

    T. Yamamoto, A. Ohashi, S. Yoneyama, M. Hasegawa, O. Tsutsumi, A. Kanazawa, T, Shiono T. Ikeda

    J. Phys. Chem. B   105 ( 12 )   2308 - 2313   2001

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  • 高分子アゾベンゼン液晶の高速ホログラム記録

    宍戸厚, 池田富樹

    光技術コンタクト   39 ( 11 )   633 - 639   2001

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  • Formation of intensity grating in a polymer liquid crystal with a side-chain azobenzene moiety by photoinduced alignment change of mesogens

    S Yoneyama, T Yamamoto, M Hasegawa, O Tsutsumi, A Kanazawa, T Shiono, T Ikeda

    JOURNAL OF MATERIALS CHEMISTRY   11 ( 12 )   3008 - 3013   2001

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    We studied the behavior of photoinduced alignment change of a polymer liquid crystal (PLC) containing an azobenzene moiety in the side chain and formation of a grating by means of the photoinduced alignment of PLCs. The alignment change was evaluated by irradiation with s-polarized light at 488 nm. We investigated the effects of light intensity and incident angles of writing beams (two s-polarized (s+s) configuration) on grating formation in PLC films, and explored the relation between the alignment change and diffraction efficiency. The diffraction efficiency showed a maximum when the change in photoinduced alignment was almost complete in the bright area of interference patterns. The maximum value obtained for the modulation of the refractive index was 0.04. These results indicate that a PLC with an azobenzene moiety is effective under (s+s) polarization conditions, compared with other azopolymer systems.

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  • Formation of intensity grating in a polymer liquid crystal with a side-chain azobenzene moiety by photoinduced alignment change of mesogens

    S. Yoneyama, T. Yamamoto, M. Hasegawa, O. Tsutsumi, A. Kanazawa, T. Shiono, T. Ikeda

    Journal of Materials Chemistry   11 ( 12 )   3008 - 3013   2001

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    We studied the behavior of photoinduced alignment change of a polymer liquid crystal (PLC) containing an azobenzene moiety in the side chain and formation of a grating by means of the photoinduced alignment of PLCs. The alignment change was evaluated by irradiation with s-polarized light at 488 nm. We investigated the effects of light intensity and incident angles of writing beams (two s-polarized (s+s) configuration) on grating formation in PLC films, and explored the relation between the alignment change and diffraction efficiency. The diffraction efficiency showed a maximum when the change in photoinduced alignment was almost complete in the bright area of interference patterns. The maximum value obtained for the modulation of the refractive index was 0.04. These results indicate that a PLC with an azobenzene moiety is effective under (s+s) polarization conditions, compared with other azopolymer systems.

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  • Photochemical modulation of refractive index by means of photosensitive liquid crystals

    T Ikeda

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   364   187 - 197   2001

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    Refractive-index modulation by change in alignment of liquid crystals (LCS) has been explored: order to disorder phase transition of LCs by photochemical reactions of photoresponsive molecules, order to order alignment change of LCs in the LC phases induced by photochemical reactions. In the order to disorder phase transition of LCs, the refractive index can be changed very quickly while the change in the refractive index is smaller than those induced by the order to order alignment change of LC molecules. In-plane (2 D) and out-of-plane (3 D) alignment change of LCs have been studied. With the out-of-plane alignment change of LC molecules, refractive-index modulation not only to linearly polarized light but also to unpolarized light can be achieved. The alignment change of LCs without photochemical processes is also discussed.

    DOI: 10.1080/10587250108024987

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  • Holographic grating by means of polymer liquid crystals

    Tomiki Ikeda, Satoshi Yoneyama, Takahiro Yamamoto, Makoto Hasegawa

    Journal of Information Display   2 ( 3 )   6 - 12   2001

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    Formation of intensity gratings was studied with two s-polarized (s+s) configuration in polymer liquid crystals (PLCs) containing a photochromic moiety (azobenzene) and a mesogenic unit (tolane, T-AB
    cyanobiphenyl, CB-AB) by photoinduced alignment of PLCs. Remarkable differences were observed between the two PLCs. T-AB showed a faster response to the change in the diffraction intensity than CB-AB. In T-AB, alignment change took place faster than that of CB-AB. By introducing the tolane unit at the side chain, we obtained a diffraction efficiency of 30 % in the Raman-Nath regime. © 2001 Taylor &amp
    Francis Group, LLC.

    DOI: 10.1080/15980316.2001.9651860

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  • Holographic grating by means of polymer liquid crystals

    Tomiki Ikeda, Satoshi Yoneyama, Takahiro Yamamoto, Makoto Hasegawa

    Journal of Information Display   2 ( 3 )   6 - 12   2001

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    Formation of intensity gratings was studied with two s-polarized (s+s) configuration in polymer liquid crystals (PLCs) containing a photochromic moiety (azobenzene) and a mesogenic unit (tolane, T-AB
    cyanobiphenyl, CB-AB) by photoinduced alignment of PLCs. Remarkable differences were observed between the two PLCs. T-AB showed a faster response to the change in the diffraction intensity than CB-AB. In T-AB, alignment change took place faster than that of CB-AB. By introducing the tolane unit at the side chain, we obtained a diffraction efficiency of 30 % in the Raman-Nath regime. © 2001 Taylor &amp
    Francis Group, LLC.

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  • 液晶フォトニクスの新展開

    金澤昭彦, 池田富樹

    光学   30   11 - 20   2001

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  • 光で駆動する液晶ナノフィルム

    宍戸厚, 池田富樹

    未来材料   1 ( 8 )   1 - 6   2001

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  • Photochemical phase transition behavior of liquid crystals in the presence of non-mesogenic molecules Reviewed

    JH Sung, O Tsutsumi, A Kanazawa, T Shiono, T Ikeda

    LIQUID CRYSTALS V   4463   173 - 180   2001

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    Photochemically induced nematic (N)-isotropic (I) phase transition behavior and domain formation of the azobenzene/liquid crystal (LC) mixtures in the presence of non-mesogenic dopants were evaluated. When a bent-shaped non-mesogenic molecule was added to the azobenzene LCs, formation of I domains was formed effectively on photoirradiation to cause the trans-cis isomerization of the azobenzene. The domain formation results from the aggregation of cis isomers, which could be enhanced to more extent with the aid of the bent-shaped dopant with a common structural feature to the cis-azobenzene. When the formation of the I domain proceeds quickly upon photo irradiation, the photochemical phase transition is induced more effectively.

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  • Synthesis and oxidative degradation of poly(ethene-ran-1,3-butadiene)

    T Shiono, O Yoshino, T Ikeda

    MACROMOLECULAR RAPID COMMUNICATIONS   21 ( 18 )   1297 - 1301   2000.12

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    Language:English   Publisher:WILEY-V C H VERLAG GMBH  

    DOI: 10.1002/1521-3927(20001201)21:18<1297::AID-MARC1297>3.0.CO;2-1

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  • Liquid crystalline coumarin polymers, 1 Synthesis and properties of side-group liquid crystalline polymers with coumarin moieties

    YQ Tian, E Akiyama, Y Nagase, A Kanazawa, O Tsutsumi, T Ikeda

    MACROMOLECULAR CHEMISTRY AND PHYSICS   201 ( 14 )   1640 - 1652   2000.9

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    This paper deals with two series of novel side-group liquid crystalline polymers containing coumarin(2H-1-benzopyran-2-one) moieties. Several kinds of polymethacrylates of Series I (Fig. 1) containing a 7- unit in the side group with or without substituent at 3 or 4 position of coumarin ring were prepared, in order to study the influence of spacers, tail groups and the positions of the tail groups on their liquid crystalline properties. These polymethacrylates (Series II, Fig. 1) containing a phenyl 7-octyloxycoumarin-3-carboxylate, which consisted of a turned ester group between the aromatic rings in the central unit of side group as compared to Series I, were also prepared. The of the thermal behavior of the two series that the structure of the side-group significantly crystalline properties of the polymers. that the polymers in Series I with substituents position of the coumarin ring exhibited mesophase with a wide temperature range, whereas the polymers with substituents at the 4 position showed no mesophase. In each polymer of Series I tended to exhibit a state, whereas each polymer of Series II tended to exhibit a crystalline state. This would be due to the different of side groups of the polymers in Series I and II, It was also revealed thar the UV-Vis absorption and fluorescence spectra were influenced by their mesogenic structures and chromophore aggregations. Furthermore, the preliminary results about the emission spectra suggested that the annealing of the polymer film had a great; influence on its fluorescence property.

    DOI: 10.1002/1521-3935(20000901)201:14<1640::AID-MACP1640>3.0.CO;2-Z

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  • Holographic gratings in the optically isotropic state of polymer azobenzene liquid-crystal films

    T Yamamoto, S Yoneyama, O Tsutsumi, A Kanazawa, T Shiono, T Ikeda

    JOURNAL OF APPLIED PHYSICS   88 ( 5 )   2215 - 2220   2000.9

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    We attempted formation of holographic gratings in an optically isotropic state of polymer azobenzene liquid-crystal films. On irradiation of writing beams at 488 nm, first-order diffraction beams of a probe beam at 633 nm were immediately observed even though the films exhibited the optically isotropic state. The diffraction beams quickly disappeared by turning off the writing beams. The first-order diffraction efficiency was affected by polarization of the writing beams. When unpolarized light was employed as the writing beams, diffraction beams were hardly observed. On the other hand, the highest diffraction efficiency was obtained with the linearly polarized writing beams. It is speculated that photoinduced alignment of azobenzene moieties in bright fringes of the interference pattern would be responsible for the grating formation. Furthermore, it was found that rubbing treatment slightly enhanced the diffraction efficiency. By turning on and off the writing beams, dynamic control of the diffraction beams could be achieved. (C) 2000 American Institute of Physics. [S0021-8979(00)10717-0].

    DOI: 10.1063/1.1287761

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  • Emission behavior of molecularly doped electroluminescent device using liquid-crystalline matrix

    H Mochizuki, T Hasui, T Shiono, T Ikeda, C Adachi, Y Taniguchi, Y Shirota

    APPLIED PHYSICS LETTERS   77 ( 11 )   1587 - 1589   2000.9

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    Electroluminescent (EL) behavior has been evaluated in a cell which contained molecular dispersion of 1,4-bis(N,N-diphenylaminophenyl-1,3,4-oxadiazolyl)benzene (OXD) in a low-molecularweight liquid crystal, 4-octyloxy-4'-cyanobiphenyl (8OCB). EL emission was observed above the temperature where the OXD/8OCB mixture showed a liquid-crystalline phase. Furthermore, we fabricated an EL device which consisted of interdigital electrodes coated onto a glass substrate. It was found that the EL emission from the device was highly polarized. (C) 2000 American Institute of Physics. [S0003-6951(00)02937-5].

    DOI: 10.1063/1.1309026

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  • Emission behavior of molecularly doped electroluminescent device using liquid-crystalline matrix

    H Mochizuki, T Hasui, T Shiono, T Ikeda, C Adachi, Y Taniguchi, Y Shirota

    APPLIED PHYSICS LETTERS   77 ( 11 )   1587 - 1589   2000.9

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    Electroluminescent (EL) behavior has been evaluated in a cell which contained molecular dispersion of 1,4-bis(N,N-diphenylaminophenyl-1,3,4-oxadiazolyl)benzene (OXD) in a low-molecularweight liquid crystal, 4-octyloxy-4'-cyanobiphenyl (8OCB). EL emission was observed above the temperature where the OXD/8OCB mixture showed a liquid-crystalline phase. Furthermore, we fabricated an EL device which consisted of interdigital electrodes coated onto a glass substrate. It was found that the EL emission from the device was highly polarized. (C) 2000 American Institute of Physics. [S0003-6951(00)02937-5].

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  • A thiophene liquid crystal as a novel pi-conjugated dye for photo-manipulation of molecular alignment

    HC Zhang, S Shiino, A Shishido, A Kanazawa, O Tsutsumi, T Shiono, T Ikeda

    ADVANCED MATERIALS   12 ( 18 )   1336 - 1339   2000.9

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    DOI: 10.1002/1521-4095(200009)12:18<1336::AID-ADMA1336>3.0.CO;2-A

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  • Photochemical modulation of color and transmittance in chiral nematic liquid crystal containing an azobenzene as a photosensitive chromophore

    HK Lee, K Doi, H Harada, O Tsutsumi, A Kanazawa, T Shiono, T Ikeda

    JOURNAL OF PHYSICAL CHEMISTRY B   104 ( 30 )   7023 - 7028   2000.8

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    All-optical switching of selectively reflected colors based on isomerization of an azobenzene (Azo) and subsequent change in transmittance was investigated in cholesteric liquid crystals (LCs) which reflect light in the visible region. Photoirradiation at 366 nm, which causes an efficient trans-cis isomerization of Azo, led to change in color of cholesteric LCs toward shorter wavelengths with a concomitant lowering of phase transition temperature from a cholesteric to an isotropic phase (TCh-I) Reversible change in color was induced all-optically by irradiating alternatively at effective wavelengths for reversible isomerization of Ate. A remarkable change in transmittance was also observed when the photoinduced change in colors was measured by a probe light with the same handedness as the helical sense of the cholesteric LCs. In the wavelength regions of reflected colors before photoirradiation, the spectral position played an important role in producing a normal-mode and a reverse-mode switching in photoinduced modulation of transmittance of the cholesteric samples with respect to the probe light.

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  • Additive effects of trialkylaluminum on propene polymerization with (t-BuNSiMe(2)Flu)TiMe2-based catalysts

    T Shiono, S Yoshida, H Hagihara, T Ikeda

    APPLIED CATALYSIS A-GENERAL   200 ( 1-2 )   145 - 152   2000.8

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    Propene polymerization was conducted by [eta(3):eta(1)-tert-butyl(dimethylfluorenylsilyl)amido]dimethyltitanium combined with B(C6F5)(3) or methylaluminoxane (MAO) as a cocatalyst in the presence or absence of various trialkylaluminums: Me3Al, Et3Al, (Bu3Al)-Bu-i (triisobutylaluminum) and Oct(3)Al (trioctylaluminum). In the case of living polymerization with B(C6F5)3 at -50 degrees C, addition of Oct(3)Al and Et3Al increased the propagation rate. Et3Al also acted as a chain transfer reagent and selectively gave Al-terminated polymers, while Oct(3)Al induced chain transfer reaction only in high concentration. Little polymer was obtained in the presence of Me3Al or (Bu3Al)-Bu-i. When MAO was used as a cocatalyst, polymerization did not proceed at -50 degrees C,The MAO system, however, showed high activity at 40 degrees C and selectively gave low molecular weight polymers terminated with Al-C bonds. Contrary to the low temperature polymerization with B(C6F5)(3) at -50 degrees C, the polymer yield was enhanced by the addition of Me3Al and (Bu3Al)-Bu-i, while the molecular weight was reduced by Me3Al and enlarged by (Bu3Al)-Bu-i. On the other hand, Et3Al and Oct(3)Al significantly decreased both the polymer yield and the molecular weight under these conditions. It was found that additive effects of trialkylaluminums were strongly dependent on polymerization temperature as well as on the structure of the alkyl group, (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0926-860X(00)00633-5

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  • Photochemical modulation of alignment in liquid crystals

    T Ikeda, A Kanazawa

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   73 ( 8 )   1715 - 1733   2000.8

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    Liquid crystals (LCs) show an anisotropic nature in various aspects of optical and electronic properties. This anisotropy enables LC materials to be used as active media in display devices. Birefringence, an anisotropy in optical properties of LCs, is especially useful from the viewpoint of changing refractive indices of LC materials. If alignment of LCs can be changed by light, a large change in refractive index can be induced by light. This is the principle of LC photonics, in which optical signals are processed with the aid of LC materials. In this article, various approaches are described to change the alignment of the LC molecules: 1) photochemically induced phase transition of LCs by photochromic reactions is an order to disorder transition and can be brought about in a time scale of micro- to nanosecond; 2) reorientation of LC molecules by means of linearly polarized light is a change in alignment of LC molecules that occurs within the LC phases and induces a large change in refractive index, but needs more time. Applications of LC systems as photonic materials are also discussed.

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  • Photoinduced alignment of polymer liquid crystals containing azobenzene moieties in the side group VII. On He-Ne laser beam irradiation

    YL Wu, JI Mamiya, O Tsutsumi, A Kanazawa, T Shiono, T Ikeda

    LIQUID CRYSTALS   27 ( 6 )   749 - 753   2000.6

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    Photoinduced alignment in a polymer liquid crystal prepared from 6-{1-[4-(2-cyano-4-nitrophenylazo)phenyl]piperazino}hexyl acrylate and 4'-[6-(methacryloyloxy)hexyloxy]-4-cyanobiphenyl was investigated for the first time on irradiation with a polarized He-Ne laser beam at 633 nm. The azobenzene moieties as well as the inert cyanobiphenyl mesogenic units were aligned with the molecular long axis perpendicular to the polarization direction of the irradiation light. Alignment induced on short irradiation was reversible, while that induced under prolonged irradiation was irreversible due to the occurrence of crosslinking which might be caused by photoinduced decomposition of the azobenzene moieties during the photoirradiation process.

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  • Optical switching and alignment of antiferroelectric liquid crystals containing an azo group

    K Shirota, Yamaguchi, I, K Kanie, T Ikeda, T Hiyama, Kobayashi, I, Y Suzuki

    LIQUID CRYSTALS   27 ( 5 )   555 - 558   2000.5

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    The optical properties of two kinds of photochromic antiferroelectric liquid crystal (AFLC) containing an azo group have been examined. Depending on the substituting group at the chiral centre, these AFLCs showed different photoinduced phase transitions by Ar+ laser light irradiation. This phase transition has led to a new form of optical switching controlled by a bias voltage. In addition, it was found that these AFLCs caused an azimuthal photoalignment effect regulated by linearly polarized Ar+ laser light irradiation. These phenomena were applied to image storage.

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  • Copolymerization of ethylene and styrene with a MgCl2-supported CpTiCl3 catalyst

    KK Kang, JK Oh, YT Jeong, T Shiono, T Ikeda

    MACROMOLECULAR CHEMISTRY AND PHYSICS   201 ( 8 )   846 - 850   2000.5

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    Copolymerization of ethylene and styrene was carried out with CpTiCl3/MgCl2-PMAO as a catalyst at various temperatures and comonomer concentrations. The present catalyst system produces a pseudorandom copolymer of ethylene and styrene beside syndiotactic poly(styrene) (sPS) and poly(ethylene) (PE). The copolymers were obtained at temperature greater than or equal to 60 degrees C, indicating the active species promoting the copolymerization being formed at elevated temperatures. On the other hand, styrene incorporation in the copolymer increases progressively with the increase of styrene concentration.

    DOI: 10.1002/(SICI)1521-3935(20000501)201:8<846::AID-MACP846>3.0.CO;2-I

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  • Multifunctional tetracoordinate phosphorus species with high self-organizing ability

    A Kanazawa, T Ikeda

    COORDINATION CHEMISTRY REVIEWS   198   117 - 131   2000.3

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    The unique features of the phosphonium salts as functional materials are reviewed, with emphasis being placed on the comparison between the phosphonium salts and the commonly available quaternary ammonium salts, which have the same structure, differing only in the positively-charged heteroatom. The antimicrobial activity of onium salts with different long-chain segments is described with special reference to structure-activity relationships. The unexpected relationship between the antibacterial activity and the aggregation behavior in aqueous solution (i.e, lyotropic liquid-crystalline properties) was revealed through systematic studies on the antibacterial activity of the phosphonium salts as a novel class of cationic biocides. Furthermore, it is shown that the phosphonium salts can act as thermotropic liquid crystals in spite of the fact that they are amphiphiles without a rigid core. (C) 2000 Elsevier Science S.A. All rights reserved.

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  • Light-scattering-mode optical switching and image storage in polymer/liquid crystal composite films by means of photochemical phase transition

    HK Lee, K Doi, A Kanazawa, T Shiono, T Ikeda, T Fujisawa, M Aizawa, B Lee

    POLYMER   41 ( 5 )   1757 - 1763   2000.3

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    Photochemical phase transition behavior triggered by photoisomerization of a guest azobenzene doped in nematic (N) liquid-crystalline (LC) domains was investigated in isotropic (I) acrylate polymers with alkyl side chains on their surfaces. These polymer/LC composite films were prepared by in situ thermal polymerization-induced phase separation method (thermal PIPS) from their starting mixtures containing a di- and a mono-functional acrylate monomer. Strong light-scattering states of the intrinsic composite films were transformed into complete transparent states by photochemical N-I phase transition of the LC domains within the polymer matrices that was induced by the trans-cis photoisomerization. Recovery process from the transparent state to the initial light-scattering state was strongly influenced by the alkyl side chains. While the composite film with short alkyl side chain acted as an all-optical switching material because the optical switching could be achieved reversibly and repeatedly between the two different optical states, the composite films with long alkyl side chain showed an ability of optical image storage with high contrast based on light-scattering mode. (C) 1999 Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0032-3861(99)00357-2

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  • Specific and chemoselective multi-alpha-arylation reaction of benzoylformic acid with or without decarbonylation in P2O5-MsOH and related acidic media

    N Yonezawa, T Hino, K Matsuda, T Matsuki, D Narushima, M Kobayashi, T Ikeda

    JOURNAL OF ORGANIC CHEMISTRY   65 ( 4 )   941 - 944   2000.2

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    In P2O5-MsOH, or related acidic media, benzoylformic acid (1) undergoes three types of di- or mono-alpha-arylation reactions with or without decarbonylation ((1) decarbonylative alpha,alpha-diarylation, yielding triarylmethanols 6, (2) decarbonylative cl-monoarylation, giving benzophenone derivatives 7, and (3) alpha,alpha-diarylation without decarbonylation, affording diarylated carboxylic acids 5) and one simple decarbonylation, without arylation, to form benzoic acid (8), instead of the conventional Friedel-Crafts acylation type reaction. The product ratios are governed by the capability of the acidic medium to form mixed anhydrides with carboxylic acids and the ability of the arenes to accept electrophiles.

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  • Holographic gratings and holographic image storage via photochemical phase transitions of polymer azobenzene liquid-crystal films

    T Yamamoto, M Hasegawa, A Kanazawa, T Shiono, T Ikeda

    JOURNAL OF MATERIALS CHEMISTRY   10 ( 2 )   337 - 342   2000.2

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    Phase-type gratings formed by photochemical phase transitions of a polymer azobenzene liquid crystal have been characterized. The sensitivity of the material was improved by a factor of 23 in the liquid-crystalline phase owing to effective induction of the photochemical phase transition in the bright fringes of the interference pattern. A mechanism for grating formation in films based on dynamics both in grating formation and for the photochemical phase transition has been proposed. Observation of the grating structure with a polarizing optical microscope confirmed that the isotropic phase induced photochemically was arranged at well defined separations. The polymer azobenzene liquid crystal showed a storage capability of &gt; 100 Mbits cm(-2) which corresponds to a resolution of &lt; 1 mu m and a spatial frequency of &gt; 1000 lines mm(-1). We also attempted holographic image storage using a photomask as an object.

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  • Holographic Gratings and Holographic Image Storage via Photochemical Phase Transitions of Polymer Azobenzene Liquid-Crystal Films

    T. Yamamoto, M, Hasagawa, A. Kanazawa, T, Shiono T. Ikeda

    J. Mater. Chem.   10 ( 2 )   337 - 342   2000

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  • Photochemical Modulation of Color and Transmittance in Chiral Nematic Liquid Crystal Containing an Azobenzene as a Photosensitive Chromophore

    H.-K. Lee, K. Doi, H. Harada, O. Tsutsumi, A. Kanazawa, T, Shiono T. Ikeda

    J. Phys. Chem. B   104 ( 30 )   7023 - 7028   2000

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  • Multifunctional Tetracoordinate Phosphorus Species with High Self-Organizing Ability

    A. Kanazawa, T. Ikeda

    Coord. Chem. Rev.   198   117 - 131   2000

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  • Novel liquid-crystalline and amorphous materials containing oxadiazole and amine moieties for electroluminescent devices

    H Mochizuki, T Hasui, M Kawamoto, T Shiono, T Ikeda, C Adachi, Y Taniguchi, Y Shirota

    CHEMICAL COMMUNICATIONS   ( 19 )   1923 - 1924   2000

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    Three 1,3,4-oxadiazole derivatives with an amine and an alkyl tail were designed and synthesized as novel electroluminescent materials; it was found that the length of alkyl tail and the structure of the amine strongly affect the phase structure of the oxadiazole derivatives.

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  • Novel liquid-crystalline and amorphous materials containing oxadiazole and amine moieties for electroluminescent devices

    H Mochizuki, T Hasui, M Kawamoto, T Shiono, T Ikeda, C Adachi, Y Taniguchi, Y Shirota

    CHEMICAL COMMUNICATIONS   ( 19 )   1923 - 1924   2000

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    Three 1,3,4-oxadiazole derivatives with an amine and an alkyl tail were designed and synthesized as novel electroluminescent materials; it was found that the length of alkyl tail and the structure of the amine strongly affect the phase structure of the oxadiazole derivatives.

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  • Photoinduced alignment behavior of polymer liquid crystals containing azobenzene moieties in the side chain Reviewed

    O Tsutsumi, YL Wu, J Mamiya, T Ikeda

    LIQUID CRYSTALS IV   4107   1 - 8   2000

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    Photoinduced two-dimensional (2-D) and three-dimensional (3-D) alignment behavior of polymer liquid crystals (LCs) with azobenzene moieties was investigated. 2-D alignment of the polymer LCs was brought about on irradiation with linearly polarized light. The effects of various factors on the phenomena were discussed in detail, and experimental conditions and structural parameters of the polymer LCs were optimized. It was found that the response could be enhanced by two methods: chemically tailoring the structure of the polymer LCs and physically modifying the alignment procedure. 3-D alignment of the azobenzene moieties was achieved on irradiation with unpolarized light. It was revealed that the azobenzene moieties were aligned along the propagation direction of the incident light. Photochemically inert mesogens underwent reorientation together with azobenzene moieties in the 2-D as well as 3-D alignment process.

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  • Optical switching and image storage by means of photochromic liquid crystals

    T Ikeda, O Tsutsumi, YL Wu

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   347   245 - 257   2000

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    Optical switching and image storage have been examined by means of photochromic polymer liquid crystals (LCs). The photoisomerization of photochromic moieties, which act as a photoresponsive switch, induced the LC-to-isotropic phase transition and the change in alignment of LCs, and they resulted in optical switching and image storage.

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  • Polar thin films produced by phosphonium liquid crystals: Two-dimensional self-assembled ionic layers with spontaneous polarization

    A Kanazawa, T Ikeda, J Abe

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   39 ( 3 )   612 - +   2000

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    DOI: 10.1002/(SICI)1521-3773(20000204)39:3<612::AID-ANIE612>3.0.CO;2-F

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  • Polar thin films produced by phosphonium liquid crystals: Two-dimensional self-assembled ionic layers with spontaneous polarization

    A Kanazawa, T Ikeda, J Abe

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   39 ( 3 )   612 - +   2000

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    DOI: 10.1002/(SICI)1521-3773(20000204)39:3<612::AID-ANIE612>3.0.CO;2-F

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  • Copolymerization of Ethylene and Styrence with a MgCl2-Supported CpTiCl3 Catalyst

    K. K. Kang, J.K. Oh, Y, T. Jeong, T, Shiono T. Ikeda

    Macromol. Chem. Phys.   201 ( 8 )   846 - 850   2000

  • Liquid-Crystalline Coumarin Polymers. I. Synthesis and Properties of Side-Chain Liquid Crystalline Polymers with Coumarin Moieties

    Y.-Q. Tian, E. Akiyama, Y, Nagase A. Kanazawa, O. Tsutsumi, T. Ikeda

    Macromol. Chem. Phys.   201 ( 14 )   1640 - 1652   2000

  • Optical Switching and Image Storage by Means of Photochromic Liquid Crystals

    T. Ikeda, O, Tsutsumi, Y. Wu

    Mol. Cryst. Liq. Cryst.   347   1 - 13   2000

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  • A Thiophene Liquid Crystal as a Novel p-Conjugated Dye for Photo-Manipulation of Molecular Alignment

    H. Zhang, S. Shiino, A, Shishido A. Kanazawa, O. Tsutsumi T, Shiono T. Ikeda

    Adv. Mater.   12 ( 18 )   1336 - 1339   2000

  • Direct evidence of the second-order dependence of propagation rate on propene concentration in living polymerization with the [t-BuNSiMe<inf>2</inf>Flu]TiMe<inf>2</inf>/B(C<inf>6</inf>F<inf>5</inf>) <inf>3</inf> catalyst

    Hideaki Hagihara, Hideaki Hagihara, Takeshi Shiono, Tomiki Ikeda

    Macromolecular Rapid Communications   20   200 - 202   1999.12

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    Propene polymerization was conducted with the [t-BuNSiMe2Flu]TiMe2/B(C6F5) 3 catalyst at -50 °C at various concentrations of propene. The polymerization proceeds in a living manner regardless of the propene concentration employed. Molecular weight of polymer obtained in a certain polymerization time with low monomer conversion increases with increasing concentration of propene. The logarithmic plot of molecular weight against propene concentration gives a straight line with a slope of 1.8, which indicates that the propagation rate is almost of second order with respect to propene concentration. © WILEY-VCH Verlag GmbH, 1999.

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  • Reversible optical control of transmittance in polymer/liquid crystal composite films by photoinduced phase transition

    HK Lee, A Kanazawa, T Shiono, T Ikeda, T Fujisawa, M Aizawa, B Lee

    JOURNAL OF APPLIED PHYSICS   86 ( 11 )   5927 - 5934   1999.12

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    We have demonstrated reversible change in transmittance of composite films, which are composed of an isotropic (I) polymer matrix and a host nematic (N) liquid crystal (LC) containing donor-acceptor type azobenzene LCs (AzoLCs) as photoresponsive molecules, by means of reversible phase transition in the LC domain. The composite films were prepared by in situ thermal polymerization-induced phase separation (PIPS) method from their homogeneous mixtures. Photoisomerization of AzoLCs was induced within the polymer network, and the resultant effect brought about isothermal change in transmittance. The photoinduced reversible and repeatable changes between opaque light scattering and clear transparent states were achieved effectively by irradiation with a monochromatic light at 366 nm. These changes are attributed to photochemical N-I phase transition and rapid thermal I-N phase transition in the host LC domain based on reversible change in molecular sharp of the guest AzoLCs. The optical effects were influenced by such factors as temperature of the composite films in the initial state and photoisomerization ability of the guest AzoLCs. The composite films acted as an optical switching material without polarizers. (C) 1999 American Institute of Physics. [S0021-8979(99)06123-X].

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  • Photoinduced alignment of polymer liquid crystals containing azobenzene moieties in the side chain. 6. Biaxiality and three-dimensional reorientation

    YL Wu, J Mamiya, A Kanazawa, T Shiono, T Ikeda, QJ Zhang

    MACROMOLECULES   32 ( 26 )   8829 - 8835   1999.12

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    A liquid-crystalline polymer of 6-[4-(4-ethylphenyl)diazenylphenyloxy]hexyl methacrylate and copolymer of the azobenzene monomer with 4'-[6-(methacryloyloxy)hexyloxy]-4-cyanobiphenyl were cast as thin films. When the polymer films with cis-azobenzenes were subjected to irradiation with linearly polarized Light at 436 nm, biaxiality of the azobenzene moieties was induced during the in-plane alignment process; when they were exposed to unpolarized light at 436 nm, three-dimensional manipulation of the polymer liquid crystals was brought about. The three-dimensional alignment behavior was examined by UV, FTIR, and polarizing optical microscopy techniques and by measuring the change in transmittance through crossed polarizers. It was found that the azobenzene moieties were aligned along the propagation direction of the irradiation light through repetition of trans-cis-trans isomerization. The induced anisotropy was large (an approximate order parameter as 0.36), reversible, and stable (more than 5 months at room temperature). Nonphotoactive mesogens, cyanobiphenyl, underwent three-dimensional reorientation efficiently together with the azobenzene moieties due to the cooperative motion.

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  • Photoinduced alignment of polymer liquid crystals containing azobenzene moieties in the side chain. 6. Biaxiality and three-dimensional reorientation

    YL Wu, J Mamiya, A Kanazawa, T Shiono, T Ikeda, QJ Zhang

    MACROMOLECULES   32 ( 26 )   8829 - 8835   1999.12

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    A liquid-crystalline polymer of 6-[4-(4-ethylphenyl)diazenylphenyloxy]hexyl methacrylate and copolymer of the azobenzene monomer with 4'-[6-(methacryloyloxy)hexyloxy]-4-cyanobiphenyl were cast as thin films. When the polymer films with cis-azobenzenes were subjected to irradiation with linearly polarized Light at 436 nm, biaxiality of the azobenzene moieties was induced during the in-plane alignment process; when they were exposed to unpolarized light at 436 nm, three-dimensional manipulation of the polymer liquid crystals was brought about. The three-dimensional alignment behavior was examined by UV, FTIR, and polarizing optical microscopy techniques and by measuring the change in transmittance through crossed polarizers. It was found that the azobenzene moieties were aligned along the propagation direction of the irradiation light through repetition of trans-cis-trans isomerization. The induced anisotropy was large (an approximate order parameter as 0.36), reversible, and stable (more than 5 months at room temperature). Nonphotoactive mesogens, cyanobiphenyl, underwent three-dimensional reorientation efficiently together with the azobenzene moieties due to the cooperative motion.

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  • Profiles of ethylene polymerization with zirconocene-trialkylaluminum/borane compound

    N Naga, T Shiono, T Ikeda

    JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL   150 ( 1-2 )   155 - 162   1999.12

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    Ethylene polymerization was conducted with bis(cyclopentadienyl)zirconium dichloride (1) and rac-dimethylsilylenebis(indenyl)zirconium dichloride (2) combined with trialkylaluminum (AlR3; R = methyl (Me), ethyl (Et), isobutyl (iBu))/triphenylcarbenium tetrakis(pentafluorophenyl)borate (Ph3CB(C6F5)(4)) or tris(pentafluorophenyl)borane (B(C6F5)(3)) to study the effect of cocatalysts on polymerization rate (R-p). When AlMe3 was used, no activity or very low activity was observed with both zirconocenes regardless of the borane compounds used. The replacement of AlMe3 to AIEt(3) or AliBu(3) with 1-AlR3/Ph3CB(C6F5)(4) caused polymerization and induction time was observed to reach the maximum R-p. Especially in the case of using AlEt3, it took about 30 min to show the activity. When B(C6F5)(3) was used, AlEt3 was not effective but AliBu(3) gave the highest activity among all the combinations of AlR3 and the borane compounds. In the case of polymerization with 2 using Ph3CB(C6F5)(4), high activity was observed with both AlEt3 and AliBu(3) without any induction period. When B(C6F5)(3) was used instead of Ph3CB(C6F5)(4) very low activity was observed with AlEt3. On the other hand, high activity was observed with AliBu(3), and the maximum R-p was found at the beginning of the polymerization. The effect of AlR3 on the formation of active species was discussed based on these results. (C) 1999 Elsevier Science B.V. All rights reserved.

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  • Profiles of ethylene polymerization with zirconocene-trialkylaluminum/borane compound

    N Naga, T Shiono, T Ikeda

    JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL   150 ( 1-2 )   155 - 162   1999.12

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    Ethylene polymerization was conducted with bis(cyclopentadienyl)zirconium dichloride (1) and rac-dimethylsilylenebis(indenyl)zirconium dichloride (2) combined with trialkylaluminum (AlR3; R = methyl (Me), ethyl (Et), isobutyl (iBu))/triphenylcarbenium tetrakis(pentafluorophenyl)borate (Ph3CB(C6F5)(4)) or tris(pentafluorophenyl)borane (B(C6F5)(3)) to study the effect of cocatalysts on polymerization rate (R-p). When AlMe3 was used, no activity or very low activity was observed with both zirconocenes regardless of the borane compounds used. The replacement of AlMe3 to AIEt(3) or AliBu(3) with 1-AlR3/Ph3CB(C6F5)(4) caused polymerization and induction time was observed to reach the maximum R-p. Especially in the case of using AlEt3, it took about 30 min to show the activity. When B(C6F5)(3) was used, AlEt3 was not effective but AliBu(3) gave the highest activity among all the combinations of AlR3 and the borane compounds. In the case of polymerization with 2 using Ph3CB(C6F5)(4), high activity was observed with both AlEt3 and AliBu(3) without any induction period. When B(C6F5)(3) was used instead of Ph3CB(C6F5)(4) very low activity was observed with AlEt3. On the other hand, high activity was observed with AliBu(3), and the maximum R-p was found at the beginning of the polymerization. The effect of AlR3 on the formation of active species was discussed based on these results. (C) 1999 Elsevier Science B.V. All rights reserved.

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  • Reversible optical control of transmittance in polymer/liquid crystal composite films by photoinduced phase transition

    HK Lee, A Kanazawa, T Shiono, T Ikeda, T Fujisawa, M Aizawa, B Lee

    JOURNAL OF APPLIED PHYSICS   86 ( 11 )   5927 - 5934   1999.12

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    We have demonstrated reversible change in transmittance of composite films, which are composed of an isotropic (I) polymer matrix and a host nematic (N) liquid crystal (LC) containing donor-acceptor type azobenzene LCs (AzoLCs) as photoresponsive molecules, by means of reversible phase transition in the LC domain. The composite films were prepared by in situ thermal polymerization-induced phase separation (PIPS) method from their homogeneous mixtures. Photoisomerization of AzoLCs was induced within the polymer network, and the resultant effect brought about isothermal change in transmittance. The photoinduced reversible and repeatable changes between opaque light scattering and clear transparent states were achieved effectively by irradiation with a monochromatic light at 366 nm. These changes are attributed to photochemical N-I phase transition and rapid thermal I-N phase transition in the host LC domain based on reversible change in molecular sharp of the guest AzoLCs. The optical effects were influenced by such factors as temperature of the composite films in the initial state and photoisomerization ability of the guest AzoLCs. The composite films acted as an optical switching material without polarizers. (C) 1999 American Institute of Physics. [S0021-8979(99)06123-X].

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  • Optical switching of nematic liquid crystal by means of photoresponsive polyimides as an alignment layer

    GH Kim, S Enomoto, A Kanazawa, T Shiono, T Ikeda, LS Park

    APPLIED PHYSICS LETTERS   75 ( 22 )   3458 - 3460   1999.11

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    Photosensitive polyimides (PIs) as an alignment layer induced optical switching of nematic liquid crystal (NLC) on photoirradiation at 366 nm. The orientation of NLC molecule was changed from homogeneous to homeotropic alignment on photoirradiation with a dc electric field as a bias. The optical switching behavior of NLC was largely affected by the chemical structures of PIs. (C) 1999 American Institute of Physics. [S0003-6951(99)02748-5].

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  • Real-time holographic grating by means of photoresponsive polymer liquid crystals with a flexible siloxane spacer in the side chain

    M Hasegawa, T Yamamoto, A Kanazawa, T Shiono, T Ikeda, Y Nagase, E Akiyama, Y Takamura

    JOURNAL OF MATERIALS CHEMISTRY   9 ( 11 )   2765 - 2769   1999.11

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    The formation of real-time holographic gratings was investigated in an azobenzene polymer liquid crystal (PLC) possessing a siloxane spacer in the side chain. Irradiation of thin films of the PLCs created a phase grating which is ascribed to periodic induction of the nematic-to-isotropic (N-I) phase transition due to photochemical trans-cis isomerization of the azobenzene moiety (photochemical phase transition). It was found that the N-I phase transition temperature of the PLC with the siloxane spacer was lower than that of the PLC without the siloxane spacer owing to flexibility of the siloxane units. This property resulted in a decrease in the irradiation temperature, leading to effective induction of the photochemical N-I phase transition by suppression of thermal cis-trans back-isomerization of the azobenzene moiety. Thus formation of the grating in the PLC having the siloxane spacer could be achieved by low intensity of the interference light compared to that in conventional PLCs including only alkyl spacers. Moreover, a grating with narrower fringe spacing could be created by depression of propagation of perturbation due to trans-cis photoisomerization of the azobenzene moiety in the LC phase.

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  • Real-time holographic grating by means of photoresponsive polymer liquid crystals with a flexible siloxane spacer in the side chain

    M Hasegawa, T Yamamoto, A Kanazawa, T Shiono, T Ikeda, Y Nagase, E Akiyama, Y Takamura

    JOURNAL OF MATERIALS CHEMISTRY   9 ( 11 )   2765 - 2769   1999.11

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    The formation of real-time holographic gratings was investigated in an azobenzene polymer liquid crystal (PLC) possessing a siloxane spacer in the side chain. Irradiation of thin films of the PLCs created a phase grating which is ascribed to periodic induction of the nematic-to-isotropic (N-I) phase transition due to photochemical trans-cis isomerization of the azobenzene moiety (photochemical phase transition). It was found that the N-I phase transition temperature of the PLC with the siloxane spacer was lower than that of the PLC without the siloxane spacer owing to flexibility of the siloxane units. This property resulted in a decrease in the irradiation temperature, leading to effective induction of the photochemical N-I phase transition by suppression of thermal cis-trans back-isomerization of the azobenzene moiety. Thus formation of the grating in the PLC having the siloxane spacer could be achieved by low intensity of the interference light compared to that in conventional PLCs including only alkyl spacers. Moreover, a grating with narrower fringe spacing could be created by depression of propagation of perturbation due to trans-cis photoisomerization of the azobenzene moiety in the LC phase.

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  • Photoinduced alignment behavior of polymer liquid crystals containing azobenzene moieties in the side chain

    T Ikeda, YL Wu

    PURE AND APPLIED CHEMISTRY   71 ( 11 )   2131 - 2136   1999.11

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    Azobenzene-containing polymeric systems are being developed as materials for photonic applications. The present work deals with the photoinduced two-dimensional (2-D) and three-dimensional (3-D) alignment behavior of polymer liquid crystals (PLCs) with azobenzene moieties in the side chain. 2-D alignment of the PLCs was brought about on irradiation of linearly polarized light. The effects of various factors such as experimental conditions and structural parameters of the PLCs on the 2-D alignment behavior have been explored in detail. The response was enhanced by two methods: chemically tailoring structure of the PLCs and physically modifying the alignment procedure. 3-D alignment of the azobenzene moieties was achieved on irradiation of unpolarized light. It was revealed that the azobenzene moieties were aligned along the propagation direction of the irradiation light. Inert mesogens underwent reorientation together with azobenzene moieties in the 2-D as well, as 3-D alignment process.

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  • Optical switching of nematic liquid crystal by means of photoresponsive polyimides as an alignment layer

    GH Kim, S Enomoto, A Kanazawa, T Shiono, T Ikeda, LS Park

    APPLIED PHYSICS LETTERS   75 ( 22 )   3458 - 3460   1999.11

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    Photosensitive polyimides (PIs) as an alignment layer induced optical switching of nematic liquid crystal (NLC) on photoirradiation at 366 nm. The orientation of NLC molecule was changed from homogeneous to homeotropic alignment on photoirradiation with a dc electric field as a bias. The optical switching behavior of NLC was largely affected by the chemical structures of PIs. (C) 1999 American Institute of Physics. [S0003-6951(99)02748-5].

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  • Phase-type gratings formed by photochemical phase transition of polymer azobenzene liquid crystals: Enhancement of diffraction efficiency by spatial modulation of molecular alignment

    T Yamamoto, M Hasegawa, A Kanazawa, T Shiono, T Ikeda

    JOURNAL OF PHYSICAL CHEMISTRY B   103 ( 45 )   9873 - 9878   1999.11

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    Unique characteristics were observed in phase-type gratings that were formed in a polymer azobenzene liquid crystal (PALC) film. Generation of sinusoidal variation of the surface of the film was confirmed by atomic force microscopy. However, comparison of the diffraction efficiency with the surface modulation revealed that the gratings could not be characterized only as conventional surface-relief gratings. In the glassy state of the film, moderate efficiency (similar to 18%) was obtained with large surface modulation (68-76 nm), whereas the gratings recorded in the nematic (N) phase showed high diffraction efficiency (similar to 28%) with slight surface modulation (33-53 nm). The diffraction efficiency was enhanced in the liquid-crystalline phase. Dynamics of the first-order diffraction beam exhibited that the grating formation was associated with photochemical phase transition of PALC. It was assumed that the isotropic (I) phases were formed by photochemical reaction of azobenzene moieties in the interference pattern at an appropriate interval. The grating would be made up by alternate arrangement of the I and the N phases as well as slight modulation of surface structure. Our speculation was supported by atomic force and polarizing optical microscopy. Anisotropy in the diffraction efficiency with respect to the linearly polarized readout beam also supported our hypothesis. It was revealed that the large enhancement of the efficiency was attributable to spatial modulation of molecular alignment.

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  • Phase-type gratings formed by photochemical phase transition of polymer azobenzene liquid crystals: Enhancement of diffraction efficiency by spatial modulation of molecular alignment

    T Yamamoto, M Hasegawa, A Kanazawa, T Shiono, T Ikeda

    JOURNAL OF PHYSICAL CHEMISTRY B   103 ( 45 )   9873 - 9878   1999.11

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    Unique characteristics were observed in phase-type gratings that were formed in a polymer azobenzene liquid crystal (PALC) film. Generation of sinusoidal variation of the surface of the film was confirmed by atomic force microscopy. However, comparison of the diffraction efficiency with the surface modulation revealed that the gratings could not be characterized only as conventional surface-relief gratings. In the glassy state of the film, moderate efficiency (similar to 18%) was obtained with large surface modulation (68-76 nm), whereas the gratings recorded in the nematic (N) phase showed high diffraction efficiency (similar to 28%) with slight surface modulation (33-53 nm). The diffraction efficiency was enhanced in the liquid-crystalline phase. Dynamics of the first-order diffraction beam exhibited that the grating formation was associated with photochemical phase transition of PALC. It was assumed that the isotropic (I) phases were formed by photochemical reaction of azobenzene moieties in the interference pattern at an appropriate interval. The grating would be made up by alternate arrangement of the I and the N phases as well as slight modulation of surface structure. Our speculation was supported by atomic force and polarizing optical microscopy. Anisotropy in the diffraction efficiency with respect to the linearly polarized readout beam also supported our hypothesis. It was revealed that the large enhancement of the efficiency was attributable to spatial modulation of molecular alignment.

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  • Photoinduced alignment behavior of polymer liquid crystals containing azobenzene moieties in the side chain

    T Ikeda, YL Wu

    PURE AND APPLIED CHEMISTRY   71 ( 11 )   2131 - 2136   1999.11

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    Azobenzene-containing polymeric systems are being developed as materials for photonic applications. The present work deals with the photoinduced two-dimensional (2-D) and three-dimensional (3-D) alignment behavior of polymer liquid crystals (PLCs) with azobenzene moieties in the side chain. 2-D alignment of the PLCs was brought about on irradiation of linearly polarized light. The effects of various factors such as experimental conditions and structural parameters of the PLCs on the 2-D alignment behavior have been explored in detail. The response was enhanced by two methods: chemically tailoring structure of the PLCs and physically modifying the alignment procedure. 3-D alignment of the azobenzene moieties was achieved on irradiation of unpolarized light. It was revealed that the azobenzene moieties were aligned along the propagation direction of the irradiation light. Inert mesogens underwent reorientation together with azobenzene moieties in the 2-D as well, as 3-D alignment process.

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  • The synthesis and polymerization behavior of bimetallic pyridine diamide complexes containing transition metal (Ti, Zr)

    KK Kang, SP Hong, YT Jeong, T Shiono, T Ikeda

    JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY   37 ( 20 )   3756 - 3762   1999.10

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    Titanium and zirconium complexes with a pyridine diamide ligand, [2,6-(RNCH2)(2)NC5H3](2-) (PDMP; R = 2,6-dimethylphenyl) have been synthesized and their catalytic behaviors investigated for ethylene polymerization. It was found that the zirconium complexes, [PDMP]ZrCl2 (7) and [PDMP][ZrCl3 x THF](2) (8), gave higher activities than the titanium complexes, [PDMP]TiCl2 (5) and [PDMP][TiCl3](2) (6). The bimetallic complexes (6, 8) gave higher activities than the corresponding monometallic complexes (5, 7). The titanium complexes gave polymers with higher molecular weight (M-w) than the zirconium complexes. The molecular weight distribution (M-w/M-n) of the polymers obtained from the pyridine diamide complexes were much broader than that of the normal metallocene catalysts. (C) 1999 John Wiley & Sons, Inc.

    DOI: 10.1002/(SICI)1099-0518(19991015)37:20<3756::AID-POLA3>3.0.CO;2-D

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  • Photochemically induced dynamic grating by means of side chain polymer liquid crystals

    M Hasegawa, T Yamamoto, A Kanazawa, T Shiono, T Ikeda

    CHEMISTRY OF MATERIALS   11 ( 10 )   2764 - 2769   1999.10

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    Dynamic holographic grating by means of photochemical nematic-to-isotropic phase transition has been studied in a polymer liquid crystal containing an azobenzene moiety with strong donor-acceptor substituents in the side chain. Periodical change in the phase structure was caused reversibly by trans-cis photoisomerization and cis-trans thermal back-isomerization of the azobenzene moiety and led to formation of the dynamic grating following change in refractive index on the order of 10(-2). The production and removal of the grating with a narrow fringe spacing of 1.4 mu m was achieved within similar to 150 and similar to 190 ms, respectively. Moreover, the optical switching behavior of the holographic diffraction was observed repeatedly by turning on and off the writing beams.

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  • Copolymerization of atactic polypropene macromonomer with propene by an isospecific metallocene catalyst

    T Shiono, SM Azad, T Ikeda

    MACROMOLECULES   32 ( 18 )   5723 - 5727   1999.9

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    Atactic polypropene macromonomer (PPM) with a number-average polymerization degree of ca 20 was synthesized by bis(pentamethylcyclopentadienyl)zirconium dichloride-methylaluminoxane and its structure was analyzed by H-1 and C-13 NMR spectroscopies. Copolymerization of propene and PPM was conducted with isospecific rac-dimethylsilylenebis(2-methylbenz[e]indenyl)zirconium dichloride using methylaluminoxane as a cocatalyst. The detailed analyses of resulting copolymers by GPC, DSC, and C-13 NMR proved that PPM was copolymerized with propene to give poly(propene-co-PPM). PPM content in the copolymer was found to be controlled by the amount of PPM in feed.

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  • Copolymerization of atactic polypropene macromonomer with propene by an isospecific metallocene catalyst

    T Shiono, SM Azad, T Ikeda

    MACROMOLECULES   32 ( 18 )   5723 - 5727   1999.9

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    Atactic polypropene macromonomer (PPM) with a number-average polymerization degree of ca 20 was synthesized by bis(pentamethylcyclopentadienyl)zirconium dichloride-methylaluminoxane and its structure was analyzed by H-1 and C-13 NMR spectroscopies. Copolymerization of propene and PPM was conducted with isospecific rac-dimethylsilylenebis(2-methylbenz[e]indenyl)zirconium dichloride using methylaluminoxane as a cocatalyst. The detailed analyses of resulting copolymers by GPC, DSC, and C-13 NMR proved that PPM was copolymerized with propene to give poly(propene-co-PPM). PPM content in the copolymer was found to be controlled by the amount of PPM in feed.

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  • Enhancement of stability in optical switching of photosensitive liquid crystal by means of reflection mode analysis

    A Shishido, A Kanazawa, T Shiono, T Ikeda, N Tamai

    JOURNAL OF MATERIALS CHEMISTRY   9 ( 9 )   2211 - 2213   1999.9

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    The optical switching behavior of azobenzene liquid crystals (LCs) was explored in terms of stability by means of reflection-mode analysis. The optical switching of the LC in the reflection-mode has been found to be repeated over 10 000 cycles, which is 10 times as stable as that obtained in the transmission-mode analysis although the same chromophore was used. It was found that the optimization of the optical system for material used is an effective approach to realize more stable optical switching.

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  • Photoinduced phase transition of nematic liquid crystals with donor-acceptor azobenzenes: mechanism of the thermal recovery of the nematic phase

    O Tsutsumi, A Kanazawa, T Shiono, T Ikeda, LS Park

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   1 ( 18 )   4219 - 4224   1999.9

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    Photoinduced nematic (N)-to-isotropic (I) and thermal I-N phase transition behaviour of liquid crystals (LCs) with donor-acceptor azobenzenes was investigated. Photoirradiation of mixtures of the azobenzenes and host LC resulted in N-I phase transition due to trans-cis photoisomerisation of the azobenzenes, and the N phase recovered when the irradiated sample was kept in the dark because of thermal cis-trans back-isomerisation. Time-resolved measurements with a laser pulse (355 or 532 nm; 10 ns fwhm) revealed that the photoinduced N-I phase transition took place within 200-300 mu s in all samples. The rate of the thermal I-N phase transition was affected strongly by the strength of the donor and the acceptor. The response time of the thermal I-N phase transition corresponded closely to the lifetime of the cis isomer of the azobenzenes, hence we can conclude that the rate-determining step of the thermal recovery of the N phase was the cis-trans isomerisation process. The time necessary for the thermal I-N phase transition decreased with increasing donor and acceptor strength, because the thermal cis-trans isomerisation of the azobenzene with a stronger donor-acceptor pair became faster. The N phase recovered within 500 ms in the mixture of the azobenzene (with tertiary amine as the donor and nitro group as the acceptor) and host LC at 37 degrees C.

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  • Photochemical control of conductivity of polythiophenes with photochromic moieties

    H Mochizuki, Y Nabeshima, T Kitsunai, A Kanazawa, T Shiono, T Ikeda, T Hiyama, T Maruyama, T Yamamoto, N Koide

    JOURNAL OF MATERIALS CHEMISTRY   9 ( 9 )   2215 - 2219   1999.9

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    The synthesis, optical and electrical properties of azobenzene-substituted polythiophene derivatives at the 3-position are reported: one without flexible spacer (PT0) and the other with a hexamethylene spacer (PT6). Photoirradiation of PT6 at 366 nm caused trans-cis isomerization of the azobenzene moiety and this photochromic reaction induced a change in conductivity of the thin film of PT6: the conductivity was 1.1x10(-7) S cm(-1) before irradiation and 8.3x10(-7) S cm(-1) after photoirradiation. After annealing, the conductivity of the film returned to the initial value. The conductivity of a compound without the azobenzene moiety, alpha-terthienyl (alpha T3), showed no change on photoirradiation at 366 nm.

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  • Photoinduced phase transition of nematic liquid crystals with donor-acceptor azobenzenes: mechanism of the thermal recovery of the nematic phase

    O Tsutsumi, A Kanazawa, T Shiono, T Ikeda, LS Park

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   1 ( 18 )   4219 - 4224   1999.9

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    Photoinduced nematic (N)-to-isotropic (I) and thermal I-N phase transition behaviour of liquid crystals (LCs) with donor-acceptor azobenzenes was investigated. Photoirradiation of mixtures of the azobenzenes and host LC resulted in N-I phase transition due to trans-cis photoisomerisation of the azobenzenes, and the N phase recovered when the irradiated sample was kept in the dark because of thermal cis-trans back-isomerisation. Time-resolved measurements with a laser pulse (355 or 532 nm; 10 ns fwhm) revealed that the photoinduced N-I phase transition took place within 200-300 mu s in all samples. The rate of the thermal I-N phase transition was affected strongly by the strength of the donor and the acceptor. The response time of the thermal I-N phase transition corresponded closely to the lifetime of the cis isomer of the azobenzenes, hence we can conclude that the rate-determining step of the thermal recovery of the N phase was the cis-trans isomerisation process. The time necessary for the thermal I-N phase transition decreased with increasing donor and acceptor strength, because the thermal cis-trans isomerisation of the azobenzene with a stronger donor-acceptor pair became faster. The N phase recovered within 500 ms in the mixture of the azobenzene (with tertiary amine as the donor and nitro group as the acceptor) and host LC at 37 degrees C.

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  • Photoinduced alignment of polymer liquid crystals containing azobenzene moieties in the side chain. 4. Dynamic study of the alignment process

    YL Wu, A Kanazawa, T Shiono, T Ikeda, QJ Zhang

    POLYMER   40 ( 17 )   4787 - 4793   1999.8

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    An anisotropy was induced in initial isotropic (polydomain) polymer liquid crystal MACB-CNAB6 by using linearly polarized light at 366 nm. The alignment processes induced at various temperatures and various intensities of irradiation light were analyzed by using a biexponential function (as shown in text). It was found that the alignment process involved two response modes: a fast response mode and a slow one. The fast response mode was associated with the angular-dependent trans-cis photoisomerization and the preliminary alignment of mesogens, while the slow one was attributed to the position adjustment of the mesogens to obtain well-aligned monodomain. The writing rate and the induced anisotropy increased with increase in temperature and in light intensity at low intensity of the irradiation light. Combined with photochemical phase transition processes, optical switching and image storage were realized in the polymer liquid crystal. (C) 1999 Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0032-3861(98)00713-7

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  • Polymerization behavior of alpha-olefins with rac- and meso-type ansa-metallocene catalysts: Effects of cocatalyst and metallocene ligand

    N Naga, T Shiono, T Ikeda

    MACROMOLECULAR CHEMISTRY AND PHYSICS   200 ( 7 )   1587 - 1594   1999.7

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    Polymerizations of propene, 1-butene and 1-hexene were conducted with a mixture of rac- and meso-[dimethylsilylenebis(2-methylindenyl)]zirconium dichloride (1) combined with methylaluminoxane (MAO), triethylaluminium (AlEt3)/triphenylcarbenium tetrakis(pentafluorophenyl)borate (2) or triisobutylaluminium (AliBu(3))/2 as a cocatalyst. The polymerization profiles of propene with rac-1 and meso-1 were determined from the rate of overall propene consumption and the fractions of isotactic and atactic polymers which were sampled during polymerization. An induction time to reach the maximum R-p (rate of polymerization) followed by gradual decay was observed in the case of using the systems rac-, meso-1-MAO and rac-1-AliBu(3)/2. Besides, a rapid drop of R-p from the initial value was found when using AlEt3/2. Molecular weights of the isotactic and atactic polymers sampled do not change during polymerization, and it is suggested that the change of [C*] (number of active centers) is reflected in the profiles of R-p. The rate ratio of rac-1 to meso-1 (R-p(rac)/R-p(meso)) in propene and 1-butene polymerizations decreases in the following order: AlEt3/2 &gt; AliBu(3)/2 &gt; MAO. In the case of 1-hexene polymerization, the highest R-p(rac)/R-p(meso) value was obtained. This result indicates that the coordination of 1-hexene to the sterically hindered site of meso-1 is difficult compared with propene and 1-butene.

    DOI: 10.1002/(SICI)1521-3935(19990701)200:7<1587::AID-MACP1587>3.0.CO;2-5

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  • In situ photopolymerization behavior of chiral liquid-crystalline monomers and image storage using ferroelectric properties

    S Ogiri, H Nakamura, A Kanazawa, T Shiono, T Ikeda, Nishiyama, I

    MACROMOLECULES   32 ( 15 )   4806 - 4813   1999.7

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    We report in situ photopolymerization behavior of ferroelectric liquid-crystalline (FLC) monomers with the polymerizable group attached to the rigid core through a long methylene spacer (carbon number of 11, MS11) and a short methylene spacer (carbon number of 2, MS2) and image storage using bistable switching of FLC monomers by applying an electric field. The polymerization behavior of MS2 was considerably different from that of MS11. This might be due to a higher concentration of the polymerizable groups in MS2. In addition, the relative conversion (the ratio of conversion under electric field to that without electric field) in the SmC* phase of MS2 was larger than that of MS11. This result suggests that the change in macroscopic structure is more effective in the polymerization of MS2 in which the polymerizable groups are more densely packed. Furthermore, the image storage was performed by in situ photopolymerization with a de electric field.

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  • Highly active MgCl2-supported CpMCl3 (M = Ti, Zr) catalysts for ethylene polymerization

    KK Kang, JK Oh, YT Jeong, T Shiono, T Ikeda

    MACROMOLECULAR RAPID COMMUNICATIONS   20 ( 6 )   308 - 311   1999.6

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    Monocyclopentadienyl compounds, CpMCl3 (M = Ti, Zr) supported on activated MgCl2 were used for the polymerizations of ethylene in the presence of methylaluminoxane (MAO) or a common alkylaluminium as a cocatalyst. By supporting CpMCl3 on MgCl2, the catalyst activity was increased drastically to show high activity similar to MgCl2-supported TiCl4 catalysts. The activity of the CpZrCl3/MgCl2 catalyst was higher than that of the CpTiCl3/MgCl2 one. Both catalysts gave polymers with high molecular weight (M,) and broad molecular weight distribution ((M) over bar(w)/(M) over bar(n)) in comparison with the corresponding soluble half-metallocene catalysts.

    DOI: 10.1002/(SICI)1521-3927(19990601)20:6<308::AID-MARC308>3.0.CO;2-N

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  • Photoinduced alignment of polymer liquid crystals containing azobenzene moieties in the side chain. 5. Effect of the azo contents on alignment behavior and enhanced response

    YL Wu, QJ Zhang, A Kanazawa, T Shiono, T Ikeda, Y Nagase

    MACROMOLECULES   32 ( 12 )   3951 - 3956   1999.6

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    A series of side-chain polymer liquid crystals (PLCs) of 6-[4-(4-ethylphenyl)diazenylphenyloxy]hexyl methacrylate and 4'-[6-(methacryloyloxy)hexyloxy]-4-cyanobiphenyl were synthesized and characterized. The effects of contents of the azo units and the wavelength of irradiation light on photoinduced alignment behavior were investigated. On irradiation of linearly polarized light (LPL) at 366 nm directly, alignment change was induced only in the PLC with 6 mol % azo units (P6), while phase transition took place in the other PLCs with higher contents of the azo units. On irradiation of LPL at 436 nm directly, alignment was induced with a fair efficiency in P15 and P35, low efficient alignment was observed in P6 and P100, and no alignment change was induced in P55 and P75, which exhibited a homeotropic state. A high alignment efficiency was achieved in all PLCs by using another method: irradiation with 366 nm unpolarized light at first and then with 436 nm LPL. The alignment change induced by this method was explored at various temperatures. All-optic switching might be realized by irradiation of 336 nm unpolarized light and 436 nm LPL alternatively based on the photochemical phase transition and the photoinduced alignment processes of the PLCs, respectively.

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  • Cyclopolymerization of 1,7-octadiene with metallocene methylaluminoxane

    N Naga, T Shiono, T Ikeda

    MACROMOLECULAR CHEMISTRY AND PHYSICS   200 ( 6 )   1466 - 1472   1999.6

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    Polymerization of 1,7-octadiene was conducted with iso specific rac-dimethylsilylenebis(indenyl)zirconium dichloride (1), syndiospecific diphenyl methylene(cyclopentadienyl) (9-fluorenyl)zirconium dichloride (2) and aspecific bis(cyclopentadienyl)zirconium dichloride (3) metallocene catalysts combined with methylaluminoxane. The microstructure of the poly( 1,7-octadiene)s produced was characterized by means of H-1 NMR, C-13 NMR and DEFT (distortionless enhancement by polarization transfer) spectroscopy. A portion of monomeric units in poly(1,7-octadiene)s is saturated as a result of cycloaddition. The fraction of the saturated units (cyclization selectivity) decreases in the following order: 1 &gt; 3 &gt; 2. The effect of polymerization temperature was studied, and the cyclization selectivity was found to decrease with lowering the polymerization temperature. The monomer concentration affects the microstructure of poly(1,7-octadiene), and the cyclization selectivity is drastically decreased with increasing monomer concentration.

    DOI: 10.1002/(SICI)1521-3935(19990601)200:6<1466::AID-MACP1466>3.0.CO;2-N

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  • Reaction routes of specific decarbonylative alpha,alpha-diarylation of 2-methoxypropanoic acid analogues in P2O5-MsOH and the related reagents

    N Yonezawa, T Hino, M Shimizu, K Matsuda, T Ikeda

    JOURNAL OF ORGANIC CHEMISTRY   64 ( 11 )   4179 - 4182   1999.5

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    DOI: 10.1021/jo981379z

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  • Direct evidence of the second-order dependence of propagation rate on propene concentration in living polymerization with the [t-BuNSiMe(2)Flu]TiMe2/B(C6F5)(3) catalyst

    H Hagihara, T Shiono, R Ikeda

    MACROMOLECULAR RAPID COMMUNICATIONS   20 ( 4 )   200 - 202   1999.4

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    Propene polymerization was conducted with the [t-BuNSiMe(2)Flu]TiMe2/B(C6F5)(3) catalyst at -50 degrees C at various concentrations of propene. The polymerization proceeds in a living manner regardless of the propene concentration employed. Molecular weight of polymer obtained in a certain polymerization time with low monomer conversion increases with increasing concentration of propene. The logarithmic plot of molecular weight against propene concentration gives a straight line with a slope of 1.8, which indicates that the propagation rate is almost of second order with respect to propene concentration.

    DOI: 10.1002/(SICI)1521-3927(19990401)20:4<200::AID-MARC200>3.0.CO;2-U

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  • Polymerization of liquid-crystalline monomers having a Schiff-base structure

    S Ogiri, M Ikeda, A Kanazawa, T Shiono, T Ikeda

    POLYMER   40 ( 8 )   2145 - 2150   1999.4

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    Vinyl monomers having a Schiff-base structure were synthesized and their thermal and photopolymerization behavior was explored for different phases of the monomers. It was found that conversion of the monomers increased with temperature in the nematic phase, while it decreased in the isotropic phase. This result suggests that the polymerization behavior may be affected by the molecular alignment. Arrhenius plots for the initial rates of photopolymerization showed a straight line, while those of thermal polymerization changed in slope at the nematic-isotropic phase transition temperature. For MBEA, the number-average molecular weight of the polymer produced by thermal polymerization in the nematic phase was higher than that in the isotropic phase. For ABBA, it was observed that birefringence partially remained in the polymer produced in the nematic phase, although polymer produced by solution polymerization showed no liquid-crystalline phase. In addition, the orientation of the crosslinked polymer obtained by photopolymerization was better than that of the polymer produced by thermal polymerization. (C) 1999 Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0032-3861(98)00421-2

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  • Copolymerization of Propene and Nonconjugated Diene Involving Intramolecular Cyclization with Metallocene/Methylaluminoxane

    Naofumi Naga, Takeshi Shiono, Tomiki Ikeda

    Macromolecules   32 ( 5 )   1348 - 1355   1999.3

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    Copolymerizations of propene with 1,5-hexadiene and 1,7-octadiene were carried out with isospecific rac-dimethylsilylenebis(indenyl)zirconium dichloride (1) and syndiospecific diphenylmethylene-(cyclopentadienyl)(9-fluorenyl)zirconium dichloride (2) combined with methylaluminoxane. Microstructures of the copolymers were determined by 1H NMR, 13C NMR, and DEPT (distortionless enhancement of polarization transfer) spectroscopies. Incorporation of nonconjugated dienes in the copolymer was higher with 2 than with 1. Intramolecular cycloaddition of the nonconjugated dienes proceeded regardless of the catalysts. Stereoselectivity in cycloaddition of 1,5-hexadiene was investigated based on the structures of isolated methylene-1,3-cyclopentane units. It was found that 1,5-hexadiene was inserted stereospecifically by enantiomorphic site control with both catalysts. The diastereoselectivity of the cyclization step of 1,2-inserted 1,5-hexadiene was, however, found to be independent of stereospecificity of the catalyst. The cyclization selectivity of 1,5-hexadiene copolymerization was higher than that of 1,7-octadiene copolymerization. I gave the copolymers with higher selective in cyclization than 2 in the propene/1,5-hexadiene copolymerization, while the opposite tendency was observed in the propene/1,7-octadiene copolymerization. Decrease of cyclization selectivity was observed with the increases of 1,5-hexadiene and 1,7-octadiene concentration in both copolymerizations. Propene insertion could disturb the cyclization of 1,2-inserted dienes, which declined the cyclization selectivity of the copolymers, except propene/1,5-hexadiene copolymerization with 2.

    DOI: 10.1021/ma9814144

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  • Three-dimensional manipulation of an azo polymer liquid crystal with unpolarized light

    YL Wu, T Ikeda, QJ Zhang

    ADVANCED MATERIALS   11 ( 4 )   300 - 302   1999.3

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    DOI: 10.1002/(SICI)1521-4095(199903)11:4<300::AID-ADMA300>3.0.CO;2-Y

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  • Copolymerization of propene and nonconjugated diene involving intramolecular cyclization with metallocene/methylaluminoxane

    N Naga, T Shiono, T Ikeda

    MACROMOLECULES   32 ( 5 )   1348 - 1355   1999.3

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    Copolymerizations of propene with 1,5-hexadiene and 1,7-octadiene were carried out with isospecific rac-dimethylsilylenebis(indenyl)zirconium dichloride (1) and syndiospecific diphenylmethylene(cyclopentadienyl) (9-fluorenyl)zirconium dichloride (2), combined with methylaluminoxane. Microstructures of the copolymers were determined by H-1 NMR, C-13 NMR, and DEFT (distortionless enhancement of polarization transfer) spectroscopies. Incorporation of nonconjugated dienes in the copolymer was higher with 2 than with I. Intramolecular cycloaddition of the nonconjugated dienes proceeded regardless of the catalysts. Stereoselectivity in cycloaddition of 1,5-hexadiene was investigated based on the structures of isolated methylene-1,3-cyclopentane units. It was found that 1,5-hexadiene was inserted stereospecifically by enantiomorphic site control with both catalysts. The diastereoselectivity of the cyclization step of 1,2-inserted 1,5-hexadiene was, however, found to be independent of stereospecificity of the catalyst. The cyclization selectivity of 1,5-hexadiene copolymerization was higher than that of 1,7-octadiene copolymerization. 1 gave the copolymers with higher selective in cyclization than 2 in the propene/1,5-hexadiene copolymerization, while the opposite tendency was observed in the propene/1,7-octadiene copolymerization. Decrease of cyclization selectivity was observed with the increases of 1,1,5-hexadiene and 1,7-octadiene concentration in both copolymerizations. Propene insertion could disturb the cyclization of 1,2-inserted dienes, which declined the cyclization selectivity of the copolymers, except propene/1,5-hexadiene copolymerization with 2.

    DOI: 10.1021/ma9814144

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  • Orientational dynamics in the crystalline and amorphous states of side-chain liquid crystalline polysiloxane probed by second harmonic generation

    M Hasegawa, N Nemoto, Y Nagase, Y Shirai, T Ikeda, J Abe

    POLYMER   40 ( 1 )   219 - 225   1999.1

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    The orientational behaviour of mesogenic chromophores in side-chain liquid crystalline polysiloxane subject to an external electric field was investigated by the measurement of second harmonic generation (SHG). The rise and decay rates of the electric-field-induced SHG intensity in the crystalline state were found to be slower than those in the amorphous state; furthermore, the SHG intensity in the crystalline state was found to be weaker than that in the amorphous state. Analysis of the rise and decay rates of the electric-field-induced SHG intensity suggested that the mesogenic chromophores in the amorphous state move independently with other mesogenic chromophores and with the siloxane backbone, whereas those in the crystalline state move cooperatively with them. (C) 1998 Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0032-3861(98)00237-7

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  • Orientational dynamics in the crystalline and amorphous states of side-chain liquid crystalline polysiloxane probed by second harmonic generation

    M Hasegawa, N Nemoto, Y Nagase, Y Shirai, T Ikeda, J Abe

    POLYMER   40 ( 1 )   219 - 225   1999.1

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    The orientational behaviour of mesogenic chromophores in side-chain liquid crystalline polysiloxane subject to an external electric field was investigated by the measurement of second harmonic generation (SHG). The rise and decay rates of the electric-field-induced SHG intensity in the crystalline state were found to be slower than those in the amorphous state; furthermore, the SHG intensity in the crystalline state was found to be weaker than that in the amorphous state. Analysis of the rise and decay rates of the electric-field-induced SHG intensity suggested that the mesogenic chromophores in the amorphous state move independently with other mesogenic chromophores and with the siloxane backbone, whereas those in the crystalline state move cooperatively with them. (C) 1998 Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0032-3861(98)00237-7

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  • Cyclopolymerization of 1,7-Octadiene with Metallocene/Methylaluminoxane

    N. Naga T, Shiono T. Ikeda

    Macromol. Chem. Phys.   200 ( 6 )   1466 - 1472   1999

  • Acid-Mediated Specific a,a-Diarylation and a-Monoarylation Reactions of Pyruvic Acid with/without Decarbonylation

    N. Yonezawa, T. Hino, M. Shimizu, K, Matsuda T. Ikeda

    Synth. Commun.   29   1687 - 1695   1999

  • Acid-mediated specific alpha,alpha-diarylation and alpha-monoarylation reactions of pyruvic acid with/without decarbonylation

    N Yonezawa, T Hino, T Kinuno, T Matsuki, T Ikeda

    SYNTHETIC COMMUNICATIONS   29 ( 10 )   1687 - 1695   1999

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    Pyruvic acid (3) was found to be arylated chemoselectively at the alpha-ketocarbonyl carbon in P2O5-MsOH affording decarbonylative alpha,alpha-diarylated products 5, decarbonylative alpha-monoarylated compounds 6, or non-decarbonylative alpha,alpha-diarylated adducts 7 depending on the reactivity of arenes (4a-g), in contrast to Lewis acid-catalyzed reaction of its acid chloride (2).

    DOI: 10.1080/00397919908086155

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  • Rheological properties of ionomer based on propylene terpolymer

    KK Kang, YT Jeong, DH Lee, T Shiono, T Ikeda

    JOURNAL OF MACROMOLECULAR SCIENCE-PHYSICS   B38 ( 3 )   227 - 236   1999

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    Ionomers based on terpolymerization of the propylene/1 -hexane/10-undecenoic acid system were prepared, and their rheological properties were studied. The complex viscosity increased in the order poly(propylene-co-1-hexene) &lt; homopolypropylene &lt; terpolymer with acid less than terpolymer with zinc salt, and the crossover modulus of terpolymers with salt or acid were shifted to a lower frequency compared with that of homopolymer. In the G'-G " plots, terpolymers with salt and acid showed some deviation. So, time-temperature superposition was not applicable to those samples. The flow activation energies showed the following order of value: homopolymer &lt; terpolymer with acid &lt; terpolymer with salt.

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  • Stereospecific Polymerization of Methacrylates with Dimethylsilylene-Bridged Zirconocene Catalysts

    N. Saegusa, T, Saito T, Shiono H. Hagihara T. Ikeda, H. Deng, K. Soga

    Macromol. Symp., Metalorganic Catalysts for Synthesis and Polymerization   583 - 589   1999

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  • Holographic grating formed by photochemical phase transition of polymer azobenzene liquid crystal

    T Yamamoto, S Yoneyama, M Hasegawa, A Kanazawa, T Shiono, T Ikeda

    LIQUID CRYSTAL MATERIALS AND DEVICES   559   153 - 158   1999

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    We explored the formation of holographic gratings by means of a polymer azobenzene liquid crystal (PALC). When two writing beams (argon-ion laser, 488 nm, unpolarized) were interfered on the surface of the PALC film (thickness, 500 similar to 600 nm), multiple diffraction beams were observed immediately, resulting from grating formation. Such generation of the diffraction beams was assumed to be due to a periodic induction of photochemical phase transition in the bright fringes of the interference pattern. The grating is namely made up of a periodic arrangement of nematic (N, dark fringes) and isotropic (I, bright fringes) phases. Observation of recorded interference patterns under a cross-polarized optical microscope supported our speculation for the structure of the grating. On the basis of these results, we succeeded in recording an image hologram of a photomask as an object.

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  • Two-dimensional superlattice self-formed by novel ionic liquid crystals and its photofunctional property

    A Kanazawa, T Ikeda

    LIQUID CRYSTAL MATERIALS AND DEVICES   559   201 - 210   1999

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    Thermotropic liquid-crystalline behavior of various complex salts, which are structurally simple amphiphiles without rigid cores, was evaluated by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffractometry. The phosphonium salts, consisting of positive phosphorus and negative chloride ions, were found to show a smectic A phase in which a homeotropic structure was formed spontaneously. It is significant that the phosphonium salts possess an advantageous feature as thermotropic liquid crystals and show a stable liquid-crystalline phase and a simple phase transition behavior in comparison with commonly available ammonium analogs. Furthermore, the introduction of divalent metal ions into the amphiphiles was revealed to result in enhancement of the thermal properties. Although the ammonium chlorides as parent compounds showed no liquid-crystalline phase (or indistinct transition behavior), the ammonium complexes possessing tetrachlorometalate ions exhibited clearly the smectic A phase in the expanded temperature range. Additionally, through the evaluation of dipolar alignment in the solid-state phosphonium assembly by second harmonic generation, it was assumed that the self-assembly can be regarded as layered polar thin films produced by two-dimensional ionic layers with an overall permanent electric polarization.

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  • A Dynamic Grating Using a Photochemical Phase Transition of Polymer Liquid Crystals Containing Azobenzene Derivatives

    M. Hasegawa, T. Yamamoto, A. Kanazawa, T, Shiono T. Ikeda

    Adv. Mater.   11 ( 8 )   675 - 677   1999

  • Two-Dimensional Superlattice Self-Formed by Novel Ionic Liquid Crystals and Its Photofunctional Property

    A. Kanazawa, T. Ikeda

    Mat. Res. Soc. Symp. Proc.   559   201 - 210   1999

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  • Rheological properties of ionomer based on propylene terpolymer

    KK Kang, YT Jeong, DH Lee, T Shiono, T Ikeda

    JOURNAL OF MACROMOLECULAR SCIENCE-PHYSICS   B38 ( 3 )   227 - 236   1999

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    Ionomers based on terpolymerization of the propylene/1 -hexane/10-undecenoic acid system were prepared, and their rheological properties were studied. The complex viscosity increased in the order poly(propylene-co-1-hexene) &lt; homopolypropylene &lt; terpolymer with acid less than terpolymer with zinc salt, and the crossover modulus of terpolymers with salt or acid were shifted to a lower frequency compared with that of homopolymer. In the G'-G " plots, terpolymers with salt and acid showed some deviation. So, time-temperature superposition was not applicable to those samples. The flow activation energies showed the following order of value: homopolymer &lt; terpolymer with acid &lt; terpolymer with salt.

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  • Stereospecific Polymerization of Methacrylates with Dimethylsilylene-Bridged Zirconocene Catalysts

    N. Saegusa, T, Saito T, Shiono H. Hagihara T. Ikeda, H. Deng, K. Soga

    Macromol. Symp., Metalorganic Catalysts for Synthesis and Polymerization   583 - 589   1999

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  • Holographic Grating Formed by Photochemical Phase Transition of Polymer Azobenzene Liquid Crystal

    T. Yamamoto, S. Yoneyama, M. Hasegawa, A. Kanazawa, T, Shiono T. Ikeda

    Mat. Res. Soc. Symp. Proc.   559   153 - 158   1999

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  • Polymerization Behaviour of a-Olefins with rac- and meso-Type ansa-Metallocene Catalysts: Effect of Cocatalyst and Metallocene Ligand

    N. Naga T, Shiono T. Ikeda

    Macromol. Chem. Phys.   200 ( 7 )   1587 - 1594   1999

  • Enhancement of Stability in Optical Switching of Photosensitive Liquid Crystal by Means of Reflection Mode Analysis

    A. Shishido A. Kanazawa T, Shiono T, Ikeda N. Tamai

    J. Mater. Chem.   9 ( 9 )   2211 - 2213   1999

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  • A Direct Evidence of Second-Order Dependence of Propagation on Monomer Concentration in Propene Polymerization with (t-BuNSiMe2Flu)TiMe2/B(C6F5)3 Catalyst

    H. Hagihara T, Shiono T. Ikeda

    Macromol. Rapid Commun.   20 ( 4 )   200 - 202   1999

  • Stereospecificity of propene polymerization with achiral titanocene-based catalysts

    H Hagihara, T Shiono, T Ikeda

    MACROMOLECULAR CHE