近藤 瑞穂

Copolymer films of photoalignable liquid crystalline (LC) copolymethacrylates comprised of a phenyl benzoate mesogen connected with N-benzylideneaniline end moiety (NBA2) and benzoic acid (BA) side groups exhibit a photoinduced reorientation behavior. Significant thermally stimulated molecular reorientation attains a dichroism (D) greater than 0.7 for all copolymer films and a birefringence of 0.113–0.181. In situ thermal hydrolysis of the oriented NBA2 groups decreases the birefringence to 0.111–0.128. However, the oriented structures of the film are maintained, demonstrating a photo-durability, even though the NBA2 side groups photo-react. The hydrolyzed oriented films show higher photo-durability without changing their optical properties.

Photoinduced reorientation of composite films of liquid crystalline polymethacrylate comprised of benzoic acid (BA) side groups with different length alkylene spacer (PnBAM n = 2, 6, 10) and N-benzylideneaniline carboxylic acid (NBA) is investigated using linearly polarized (LP) 365 nm light. Significant thermally stimulated in-plane molecular orientation is attained when P6BAM (n = 6) is used, but higher amount of NBA is required for the in-plane reorientation of P2BAM (n = 2) films and out-of-plane motion of the BA side groups is observed for P10BAM (n = 10) films.

安息香酸（BA）側基を有するメタクリレートとn-ブチルメタクリレートからジブロック共重合体およびランダム共重合体を合成し、BAとのH結合を支配するN-ベンジリデンアニリンカルボン酸（NBA）をドープした薄膜の光誘起再配向を、直線偏光（LP）365nmおよび313nmの光を用いて調べた。BA側鎖の配向とNBAの昇華は、ジブロック共重合体フィルムでは熱刺激により十分に達成されたが、ランダム共重合体では熱処理によりランダム配向となった。さらに、NBAをドープしたフィルムにフォトマスクを用いてLP光を照射したときのフィルムの表面レリーフ（SR）形成について調べた。液晶特性、熱特性、軸選択的光異性化、フィルムの光架橋が、分子再配向とSR形成に重要な役割を果たしている。

Photoalignment of low-molecular-liquid crystalline (LC) cell is explored without surface treatment of the substrates. A linearly polarized (LP) light exposure to a LC cell containing nematic LCs and a small amount of photoresponsive material generates homogenous LC orientation of the cell. Material design, mixture ratio and exposure condition are investigated.

<p>A photo-cross-linkable liquid crystalline polymer (PMCB6M) film can be applicable to LC alignment layer. In case of LC alignment, a near surface structure of alignment layer is most important. We investigated three-dimensional molecular orientation of oblique aligned PMCB6M films in bulk and near surface determined by UV-vis absorption spectroscopy and near edge X-ray absorption spectroscopy (NEXAFS).</p>

<p>Supramolecular liquid crystal using the interaction of pyridine-carboxylic acid is known to many. On the other hand, previously, we have reported that the axis-selective anisotropy is generated by irradiating the LPUV light in the thin film of the hydrogen bonding liquid crystal polymers having a cinnamic acid in the side chain terminal, and the anisotropy is amplified in a perpendicular direction to the polarization electric field E by heat treating it in the LC temperature range. In this presentation, we report the results for the photo-alignment behavior when various pyridine compounds were added in this polymer.</p>

<p>Photoalignment can be applicable to optical information storage, polarization holography, and photoalignment of low-molecular-weight liquid crystals (LCs). To date, several types of photoreactive liquid crystalline polymers (PLCPs) realize an effective thermally stimulated photoinduced molecular orientation. We synthesized liquid crystalline polymer with N-benzylideneaniline (NBA) side group, and found that the polymer reoriented using LP light. In this study, in order to expand the cooperative molecular reorientation, I synthesize copolymer comprised of NBA sidegroup as photoreactive group, and cyanobiphenyl side group as non-photoreactive group.</p>

<p>Mechanochromic luminescence (MCL) is an isothermal change in photoluminescence in excess of two states, and at least one pathway is induced by mechanical stimuli such as grinding, s hearing, pressing and stretching. This property is expected for mechanical sensor, cellular imaging, detection of microenvironmental changes, and optical memory. In this work, we prepared novel liquid -crystalline MCL compounds containing acetylene or 1,2,3 -triazole in π-conjugated component. The dyes changed their photoluminescent color by mechanically grinding and reverted to initial state upon annealing at their liquid-crystalline temperture. In addition, the LC dye formed uniaxially alignment when it coa ted on photoalignment layer.</p>

<p>Charge transport properties of liquid crystalline semiconductors can be controlled by tuning their aggregation structure and orientational state. In the previous work, we synthesized liquid crystalline oligothiophene based on cyano vinyl terthiophene and investigated their molecular orientation behavior on the photo-alignment film. In this study, we reported electrical and optical properties of two types of liquid crystalline vinyl terthiophene with a nd without cyano side subst ituent and explored the effect of the cyano side group on the electrical properties.</p>

In this paper, we reported novel liquid-crystalline luminophore that switches its photoluminescent color by mechanically grinding. Mechanochromic luminescence (MCL) is expected for mechanical sensor, cellular imaging, detection of microenvironmental changes, and optical memory. In this work, we focused on liquid-crystalline MCL compounds on alignment layer. Controlling the molecular alignment of MCL compounds with photoalignment layer have potential to succeed in functional MCL film such as polarized micropatterned MCL and directional detection of mechanical stimuli. Herein, we prepared asymmetric rodlike MCL compounds containing cyano-and pyridyl molecular terminal and explored their photoluminescence behavior under mechanical stimulus. The cyano terminated compound showed a nematic phase and tuned its photoluminescent color from green to yellow upon grinding, while the pyridyl-terminated compounds that show no mesophase changed its photoluminescent color from blue to green and reverted to its initial color by heating above its melting point. The cyano-terminated MCL was aligned along the orientation direction of photoalignment layer and pyridyl-terminated MCL exhibited uniaxial alignment when it coated on photoaligned film containing carboxylic acid.

Nonsinusoidal and asymmetric surface relief (SR) gratings, formed in azobenzene-containing polymeric films by elliptical polarization holographic recordings, were theoretically characterized. The amplitude of SR deformation was formulated on the basis of the optical-field gradient force model and calculated using the electric field of the interference light and the dielectric polarization of the recorded film. The observed SR gratings with asymmetric structures were well explained by considering the Weigert effect of azobenzene molecules. This observation suggests that SR deformation on the azopolymer film originating from mass transportation is affected by the distribution of optical anisotropy induced by the reorientation of the azobenzene molecules. © 2014 The Japan Society of Applied Physics.

The cooperative molecular reorientation in methacrylate copolymer films comprised of hexamethylene spacer groups terminated with photoreactive hydrogen (H) bonded 4-oxycinnamic acid (CA) and 4-oxy-4'-methoxyphenylbenzoate (MBe) in their side chains was investigated by irradiating with linearly polarized ultraviolet light (LPUV) and subsequent annealing. Both CA and MBe side groups were miscible in all the copolymer composition, and axis-selective photoreaction of both side groups was observed. A thermally enhanced cooperative in-plane orientation of both side groups perpendicular to the polarization (E) of LPUV light was obtained when the exposed films were annealed in the liquid crystalline temperature range of the copolymers. The generated birefringence of the reoriented film was 0.12 - 0.16 and the processing temperature was controlled between 85 and 165 degrees C by adjusting the copolymer composition.

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.

Crosslinked azobenzene liquid-crystalline polymer films with hybrid alignment were prepared by in-situ photopolymerization and their photoresponsive behavior was investigated. It was found that the films showed photoinduced bending and unbending behavior. The bending direction of the films was determined by surface alignment treatment. In addition, thermomechanical analysis was performed to measure mechanical force generated during the bending process.

Liquid-crystalline elastomers (LCEs) show both the elastic properties of rubbers and the anisotropy of liquid crystals. In this study, we synthesized a liquid-crystalline (LC) monomer with an azobenzene moiety and a flexible oxyethylene spacer. LCE films, which show low glass transition temperature, were prepared by thermal polymerization of the LC monomer and a cross-linker. The photoresponsive behavior of these LCE films were investigated. Because of high mobility of the oxyethylene spacer, the LCE films show low glass transition temperature and the lower stability in the alignment of mesogens even in the cross-linked structure.