Recently a mean-field model for the ferroelectric ordering of hard spherocylinders with dipolar interaction was developed within the Onsagar formalism. It was found that there exists usual isotropic-nematic, nematic-ferronematic, and direct isotropic-ferronematic phase transitions. The lyotropic polypeptide liquid crystal serves as a model system of this kind. Using the poly(γ-benzyl Lglutamate) (PBLG) in 1,1,2-trichroloethane (TCE), we observed transmittance and second-harmonic generation (SHG) under the application of an electric field and confirmed the switching of nonlinear polarization.

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A real-time measurement system for time dependent twist angles is developed. This system utilizes two circularly-homogeneously aligned LC cells which work as peculiar polarizes. Since its measurement procedure does not include any mechanical movements or rotations of optical components, this method is useful for the real-time measurement. A twist angle of a TN LC cell with PMMA films is measured by the proposed method. The time dependence of the twist angle is successfully estimated with the high time resolution.

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Reverse-twist disclination lines with ±90° and ±180° twists in LC polarization-converting devices are investigated. The generation processes of such two sates are discussed experimentally. It is found that the ±180°twist state can be transformed into the ±90°twist state by stimulating the LC cell. Namely, the ±90°twist state is deduced to be more stable than the ±180°twist state. The LC molecular orientations around the reverse-twist disclination lines with the ±90° and ±180° twists are estimated by computer simulations. It is found that the LC cell with ±180° twist state shows "an escaped structure in the third dimension" while the LC cell with ±90° twist state shows an almost planer structure.

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The threshold behavior of the in-plane switching (IPS) mode LC cells with different (asymmetric) anchoring strength at two LC/substrate interfaces was investigated by linear stability analysis. Similarity in stability characteristics between the IPS mode and the surface stabilized ferroelectric mode was clarified. The analysis showed that, with parallel rubbing of the two substrate surfaces, only the (symmetric) switching initialized from the center of the liquid-crystal layer will occur even with the asymmetric surface condition.

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Alignment properties of a polyvinyl-acetate (PVAC) and polymethyl-methacrylate (PMMA) are investigated in the homogeneous and TN cells. The LC alignment becomes thermally stable and the azimuthal anchoring energy increases with the passage of time in the homogeneous cell. On the other hand the twist angle decreases in the TN cell and the anchoring energy depends on the twist angle. Moreover, the alignment property of which surface wets for the first time with the LC in the nematic phase is different from that in the isotropic phase.

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Vertically-aligned liquid crystal displays (VA-LCDs) have recently attracted people's interest due to their characteristics of wide viewing angle and fast switching speed. But the detaited study of the effect on the EO performance of the surface anchoring properties has not been done so far. In this study, we investigate the surface anchoring properties of VA samples and its effect on the switching dynamics of amorphous VA-LCDs.

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It is experiemntally demonstrated that selecting a proper wave length of the incident light is required to aviod the Mauguin Minimum condition in which the actual twist angle cannot be estimated by optical measurement. The all of the optical component such as the glass substrates, indium tin oxide electrode films, alignment films and liquid crystals itself play an important role in the optical polarization state of the outgoing light, therefore, we re-examined the measurement method for the evaluation of the anchoring strength and proposed a modified method by using multicolor laser.

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The liquid crystal (LC) director reorientation at the interface between a substrate and an LC layer was investigated by the dye-doped reflection ellipsometry (DDRE). The experimental results demonstrated that the response of the ellipsometric angles under the applied voltage were in good agreement with the numerical results where the optical components such as the glass substrate, an insulating film, an ITO film and an alignment film were taken into account. From the analysis of the experimantal results, it was found that the DDRE has a potential to evaluate the polar anchoring strength of LC cells.

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Optical flickering effect in a nematic ECB cell under a bipolar electric field has been studied by total reflection time-resolved spectroellipsometry (TRSE). The origin of flickering effect is discussed in terms of a change in internal electric field and thereby induced director fluctuations. The flickering effect can be compensated and may change its sign when a bias electric field is applied. Moreover, the director decay shows a strong frequency dependence. It is also shown that the essential feature of the observed flickering effect can be reproduced by a simulation that assumes ion migration and director reorientation.

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Dynamic response of ferroelectric liquid crystals at the alignment film surfaces and in the bulk were investigated by time-resolved spectroellipsometry (TRSE) in bookshelf-type surface stabilized ferroelectfic liquid crystal (SSFLC) cells with different alignment filmS. Comparison of the results of total-reflection and transmission TRSE experiments indicates that the dynamic behavior of the surface molecules is different from that of the bulk molecules and that the surface tilt angle is markedly changed when the alignment film is changed.

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We have studied liquid crystal microemulsion which is made by the mixture of the thermotropic and lyotropic liquid crystals. We have found for the first time the transparent nematic(TN) phase where nematic director is locally distorted by the randomly dispersed inverse micelles. Thus, system has isotropic nature, nevertheless nematic order is completely accomplished. By using the dynamic light scattering, we measure the temperature and concentration dependence of the collective diffusion constant of inverse micelles both in the isotropic and transparent nematic phase. Collective diffusion motion of inverse micelles in the TN phase is faster than isotropic phase because of the existence of the apparent interaction between inverse micelles, which is originated by the locally deformed nematic director field.

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The first-order hyperpolarizabilities βs were determined by hyper-Rayleigh scattering in two homologous series of two-dimensional bent-shaped molecules with alkyl and alkoxy end chains. It was found that the β values in alkyl and alkoxy materials are nearly the same and slightly increase with increasing the chain length, from ca. 10×10^<-30> esu to ca. 40×10^<30> esu. Using the β value determined in the present study and the dihedral angle of the bent-shaped molecule, the tensor elements of β were also determined. Moreover, the nonlinear electric susceptibilities estimated by β were consistent with the previous bulk SHG measurement.

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Just 150 years ago, Pasteur found by optical microscopy that crystals of a sodium ammonium salt of "acide racemique" were spontaneously resolved into two enantiomorphos forms. In spite of extensive effort, no one has succeeded in observing the same phenomenon in a fluid state because of the thermal fluctuation and diffusion. We report spontaneous chiral optical resolution in a fluid system of a racemic diastereomer, (R,S)-β-Me-TFMHPOBC. In a homogeneous cell, the smectic liquid crystal of the racemate of diastereomeric molecules was found to exhibit an electrooptic response and a bistable domain switching in the SmC-like phase, although no macroscopic dipole is expected to exist. Moreover, the homeotropic cells of this material exhibit striped domains. The striped domains are associated with fine stripes having two opposite tilt senses with respect to the predominant stripes, indicating the co-existence of right- and left- handed homo-chiral domains.

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Layer structure and clectrooptical switching were studied in a bent-shaped liquid crystal motecule, P-12-PIMB. By the application of a de field during slow cooling from the isotropic to the highest temperature smectic phase, B2, large uniform domains were obtained. In the B2 phase, antiferroelectric structure was confirmed, and the molecular tilt angle was found to be 34°by the texture observation. In addition, domains with a smaller apparent tilt angle were also obtained. Basically, tilt directions with respect to the smectic layer normal are equivalent, since the molecules do not have any chiral carbons. Actually, two types of the homogeneously chiral domains were proposed by Link et al [1]. Moreover, all of the molecules in a certain layer tilt to a certain direction. Therefore, the existence of the domains with smaller tilt angle suggests that the layers with opposite senses of chirality are mixed in the domain, and that the molecules are possibly aligned like the orientation of the ferrielectric subphases of antiferroelectric liquid crystals.

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In the soft materials like liquid crystals, the responses to the external forces become easily nonlinear ones. We have developed the system for measurement of the nonlinear dielectric relaxation spectrum in a frequency domain and applied it to the ferroelectric liquid crystal (FLC) in the SmC phase. The profiles of the measured linear and nonlinear spectra make good agreements with the theoretically predicted ones. We also find that it is possible to measure the three material constants including, spontaneous polarization and rotational viscosity, simultaneously by this method.

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The ferroelectric liquid crystals (FLCS) with a naphthalene ring have a bookshelf layer structure for the particular alignment film in the chiral smectic-C (SmC) phase, and thus they have been a matter of great interest from the points of both basic research and applications to display devices. Therefore, we have investigated in the molecular structure and dynamics in the SmC phase by using polarized infrared and time-resolved infrared spectroscopy. Infrared spectroscopy enables one to investigate molecular structure and alignment because it gives much information of molecular vibrations. In this study we observed that a carbonyl group in this sample had different alignment from another one, and we have suggested a molecular structure model from the alignments of each carbonyl group.

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A field induced molecular reorientation process of a freely suspended ferroelectric liquid crystal film has been studied. In order to measure a direction and magnitude of birefringence of the freely suspended ferroelectric liquid crystal film, a phtoelastic modulator (PEM) has been used. The PEM is very useful device for fast ellipsometry, so that successional measurement of molecular orientation in the process of the reorientation can be carried out.

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Polarization reversal process in thick cell of ferroelectric liquid crystal has been studied. The transmitted light through the cell at the instant of polarity reversal of applied voltage has been diffracted by the formation of periodical stripe texture. This stripe texture is tilted to the smectic layer and the tilt direction depends on polarity of applied voltage. The oblique angle from smectic layer of stripe texture increases with applied voltage and the length of the stripe decreases with applied voltage. The peak of the polarity reversal current with the polarity reversal of applied voltage coincides with the dip of the transmitted light intensity, while the current returns quickly to the original level as compared with the transmitted light intensity.

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Azobenzene liquid crystals show photochemical nematic (N) to isotropic (I) phase transition due to trans-cis photoisomerization of the azobenzene moieties. However, recovery of the N phase requires a relatively long time at room temperature. Recently, we found that a fast I-to-N phase transition can be induced by applying electric fields. This was assumed to be due to presence of ionic species in the liquid-crystalline materials. In this study, we investigeted the effect of doped-ion species on the I-to-N phase transition of the azobenzene liquid crystal induced by application of the electric fields.

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Photochemical phase transition of photochromic azobenzene liquid crystals (LCs) was explored by means of a pico-second laser pulse. On irradiation with the laser pulse at 355 nm, which causes trans-cis photoisomerization of the azobenzene moiety, nematic (N)-to-isotropic (I) phase transition was induced rapidly: The disappearance of the initial N phase occurred in 1 μs.

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Photoresponsive liquid crystalline polymer networks with macroscopically uniaxial molecular orientation were prepared by polymerization of mixtures of liquid crystalline mono and di-acrylates, and azobenzene compound in a homogeneous glass cell at a nematic phase. The photoisomerizatiion of the azobenzene compound resulted in a change in a birefringence. The photochemical change in the birefringence was investigated by using a single pulse irradiation from a Nd:YAG laser as light source. In the liquid crystalline polymer network with 5mol% of cross-linking density, we observed a response time in a range of a few microseconds and a restoration time in a range of a few microhundreds of seconds.

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We prepared composite films by polymerization of mixtures of low molecular weght liquid crystal E44, liquid crystalline mono- and di-acrylates, an azobenzen compound in the homogeneous glass cell. The composite films were found to show optical switching between transparent state and opaque state by UV irradiation to cause trans-cis photoisomerization of the azobenzen compound. The initial state was transparent state due to a uniaxial alignment, and the final state after irradiation was opaque state. The trans-cis photoisomerization disorders the molecular orientation of liquid crystalline molecules, and cosequentty causes the biphasic state of liquid crystalline phase and isotropic phase. The biphasic state causes the opaque state. In this study, we investigate the influences of the mono- and di-acrylates on the photochemical light scattering behavior.

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We investigated formation of holographic gratings in the isotropic phase of polymer azobenzene liquid crystals (PALCs)o On irradiation of interfering light at 488 nm (writing beams), a first-order diffraction light of readout beam operating at 633 nm was immediately observed even though PALCs exhibited optically isotropic state. Diffraction efficiency depended on the polarization direction of the writing beams. When linearly polarized beams were employed for the writing beams, the highest diffraction efficiency was obtained. Polarized absorption spectra of PALC films showed the alignment change of the azobenzene moieties by irradiation of the linearly polarized light at 488 nm, in which the azobenzene moieties aligned perpendicular with respect to the polarization direction of the light. Therefore, it was speculated that photoinduced alignment of azobenzene moieties was caused in bright regions of interference pattern. Rise and decay times of the diffraction signal were evaluated as approximately 400 and 300 ms, respectively. Furthermore, the grating formation could be controlled repeatedly by turning on and off the writing beams.

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This study describes photoresponsive behavior of tetrathiafulvalene (TTF) liquid crystal (LC) in bulk and in guest-host systems. The TFF-based LC was mixed with 4'-pentyl-4-cyanobiphenyl (5CB) at a concentration of 2 mol%. The mixture was put into a glass cell (cell gap = 10 μm), which had been coated with poly(vinyl alcohol) and rubbed to align mesogen. The cell was annealed at a temperature just below clearing temperature to yield a monodomain of N phase. The cell was irradiated at 436 nm from a high-pressure mercury lamp and the intensity of a probe light at 633 nm from a He-Ne laser transmitted through a pair of crossed polarizers, with the cell between them, was measured with a photodiode. When the sample was irradiated in LC phase, the transmittance of the probe light changed immediately. The transmittance change might be induced by the change in the birefringence of the sample.

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Photopolymerization of a ferroelectric liquid-crystalline monomer, (R)-methylheptyl 4'-(4-(ω-methacryloyloxyundecyloxy)benzoyloxy)biphenyl-4-carboxylate, was carried out, using a photoinitiator (Ciba Geigy, Irgacure 784) under an electric field with an argon-ion laser at 488 nm. Initial alignment of mesogens was retained and stabilized by polymerization. With the reverse electric field, change in alignment of mesogens was brought about slowly. A sample with a higher conversion exhibited slower response to electric field. Furthermore, material having refractive index distribution was prepared by photopolymerization with Gaussian laser beam.

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We synthesized novel thiophene-based LCs with different numbers of thiophene rings (TR4 and TR5). They were doped as an active dye into LC hosts to evaluate the laser-induced reorientation by means of optical Freedericksz transition (OFT). The threshold intensity of light for the OFT was significantly decreased both in a polar host (5CB) and a non-polar host (MBBA) in the presence of a small amount of TR5 as compared to that for pure LC hosts. It has been confirmed that the LC host tends to reorient parallel to the polarization of the incident light in TR5-doped 5CB upon irradiation.

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We have characterized carrier transport properties in SmF and SmG phases of 2,5-dialkyl- 2,2':5',2"-terthiophene derivatives by transient photocurrent measurements. In these phases, fast ambipolar carrier transport was observed, and the hole and electron mobiltries were 3×10^<-3> cm^2/Vs and 2×10^<-2> cm^2/Vs respectively. These liquid crystal cells (ITO/ITO, d = 2 gin) exhibited electroluminescence when a bias of 50 V was applied. The lower threshold voltage was attributed to lower LUMO and higher HOMO levels than those of 2-phenylnaphthalene derivatives.

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In this report we have demonstrated that camer transport in calamitic liquid crystalline semiconductive materials does not suffer from structural defects even when the thickness of liquid crystalline layer exceed 100 μm. Furthermore, we firstly achieved the image recording with the liquid crystalline semiconductor by utilizing of its superior photo-electrical properties: a 2-phenylnaphthalene was used as a thick photoconductive layer (100pm) between ITO-coated glass substrate and an insulative PET film of 12μm; the photo-induced capacitive image on the PET film was developed with toner as in case of Electrophotography. The resulting defect-free toner image proved that the domain boundary of the polydomain structure does not obstruct the charge transport in the liquid crystalline semiconductor.

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Anomalous molecular alignment of liquid crystalline conducting polymer including triple bonds in the main chain, poly(2,5-dialkoxy -p-phenylenebutadiynylene), has been studied. The uniform molecular alignment with high quality in a sandwich cell has been realized by means of a conventional rubbing technique. It has been found that, instead of mesogenic main chain, alkoxy side chain aligns along the rubbing direction. This anomalous molecular alignment has been confirmed using polarizing spectroscopic measurements such as Raman, absorption and photoluminescence spectroscopies.

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Carrier transport characteristic in the chiral smectic C phase of the 2-phenylnaphthalene derivative, which exhibited ferroelectricity and photoconductivity was studied with steady-state and transit photoconductivity measurement, in order to investigate the effect of the ferroelectricity on the carrier-transport in the phase. The results of the experiments indicate no influence of the ferroelectricity on the carrier mobility and photoconductivity, perhaps because the spontaneous polarization in the phase was too small(<1nC/cm²).

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A smectic-A phase grown from an isotropic phase exhibits a rich variety of shapes such as droplets, filaments and several compact domains [1-3]. We have experimentally found that an average radius of hemispherical smectic-A domains formed on a substrate surface is decreased with increasing applied electric field. In this presentation, we report the experimental result of electric-field application to smectic-A domains, and show that this experimental finding can theoretically be explained within the framework of an elastic theory by assuming that the spontaneous curvature is induced by electric-field application.

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We observe electric field-induced motion of polymer particles with nematic liquid crystal along a rubbing direction in an anti-parallel cell. Direction of the motion is determined by the polarity of ac electric field. The velocity depends on particle size. We presume that flow of liquid crystal in the adjacent region to electrodes of the celt is generated by ac electric field. Flow direction is completely dependent upon a rubbing direction of the cell. Particles are drawn toward to either electrode by electric field. The particles accordingly move by the unidirectional flow of liquid crystal close to the electrode.

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The liquid crystalline properties of nitrobenzenes and benzonitriles with a 2-perfluoroalkyl ethoxy group at the meta or the para position have been examined. These compounds tend to show a smectic A phase as well as a smectic B one when the perfluoroalkyl chain is long enough. The layer spacings of the smectic A phase are always longer than the calculated moleclar lengths and are strongly dependent on the position of the polar groups, where the polar interaction around the cyano or the nitro group is of primary importance. Tile layer spacing of the smectic B phase is always twice of the calculated molecular length.

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The substituent effect on liquid crystalline properties for 4-R-phenyl 4-(4-octyloxybenzoyloxy)-benzoates, 4-octyloxyphenyl 4-(4-R-benzoyloxy)benzoates, 4-(4-octyloxybenzoyloxy) phenyl 4- R-benzoates, and 4-octyloxyphenyl 4-R-phenyl terephthalates (R=alkoxy, halogens, CF_3, OCF_3, NO_2, CN, and so on) has been examined. The layer spacing for the smectic A phase was determined by an X-ray diffraction experiment, indicating that the smectic A phases for the long alkyl and alkoxy derivatives have a monolayer arrangement, and those for the others have a partially bilayer one, where the ratios of the layer spacing to the molecular length are fairly dependent on the electrostatic nature of the substituent rather than the relative orientation of the ester linkages.

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Ferroelectric liquid crystalline (FLC) substituents with fluormated asymmetric moleties were introduced into the 3-position of thiophene ring. The polymerization of 2, 5 - dibrominated thiophene monomers were carried out through dehalogenative polycondensation giving rise to poly (3-FLC substituted thiophene) derivatives, which were fusible and soluble in ordinary organic solvents. Number-average molecular weights of the polymers were 1.2x10^4. UV-Vis absorption bands were observed in the region from 400 to 415 nm. Phase transition behaviors of the polymers and monomers were examined by differential scanning calorimetry (DSC), polarizing optical microscope (POM) and X-ray diffraction (XRD) measurements. It was found that one of the polymers showed chiral smectic C phase in the heating and cooling processes. The polymer showed a drastic temperature dependence of dielectric constant, which can be regarded as typical FLC behavior.

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Polythienylene derivatives with ferroelectric liquid crystaglinity (FLC) were synthesized by introducing fluorine-containing chiral liquid crystalline substituents into the 3-position of thiophene rings. The polymers synthesized were fusible and soluble in ordinary organic solvents. Measurements of DSC, POM, and XRD indicated that the polymers have various liquid crystalline phases. Particularly, two of them showed chiral smectic C (Sc) phase, characteristic of the ferroelectric liquid crystallinity. Electrical and optical properties of the polymers were discussed.

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Poty(p-phenylenevinylene) (PPV) derivatives with ferroelectric liquid crystallinity were synthesized. The fluorine-containing chiral liquid crystalline substiments with different methylene spacer (6,10) were introduced in the side chains. The di-substituted precursor monomer showed various LC phases such as chirat nematic (N) (N), twist grain boundary A (TGB_A), and chirat smectic C (Sc) which is characteristic of ferroelectric liquid crystallinity. The PPV derivatives synthesized showed a stable enantiotropic Sc phase. Besides the polymers were fluorescent.

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V-shaped switching liquid crystal material is smectic liquid crystal which is suitable for the TFT-LCD, and we are developing this material actively at present as going together the wide view angle and the high-speed responce. This material is in the relations which are close to Antiferro liquid crystal(AFLC) that shows double hysteresis responce. It is known that the chemical structure of the chiral part is closely related to the appearance of antiferro phase. So, we have investigated the relation between the chemical structure of chiral part and the appearance of V-shaped switching, and it is found that the most of compounds having similar chemical structure as AFLC show V-shaped switching. Also, it is known that the cell conditions are important for the appearance of V-shaped switching. It is found that thicker insulation layers of the cell contributes to the good appearance of V-shaped switching.

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We have studied an electro-optic properties of a chiral smectic liquid crystals: 4-(1-trifiuoromethyl-6-ethoxy-hexyloxycarbonylphenyl)-4'-nonyloxybiphenyl-4-carboxylalc (TFMEOHNBC). In a chiral smectic phase, the electro-optic switching shows nearly thresholdless behavior. On approaching SmC_y -SmA transition, tile V-T curve shown increase linearly with increasing apphed voltage. An anomaly in the response time is observed in the intermediate range of the electric field. We have measured the layer ttfickness of TFMEOHPNBC by X-ray diffraction. The temperature dependence of the layer thickness is discussed with respect to the liquid crystal phases.

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We have investigated phase transition behavior of a binary mixture between the dichiral liquid crystal with the optically isotropic phase and its stereo isomer by means of differential scanning calorimetry and optical microscopy. There is marked difference in the phase diagram between cooling and heating. Furthermore the phase diagram on heating shows a clear discontinuity. We discuss reorganizaition of the molecules by chiral recognition.

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We synthesized poly(phenylenevinylene) derivatives containing ethylene oxide moiety in the side chain by base-promoted dehydrohalogenation. A nematic phase was exhibited for these polymers. The electrical conductivity was improved by anncaling above the glass transition temperature about 10 times. The absorption and emission peaks shifted to longer wavelength with increasing the monomer unit containing ethylene oxide chain. Ionic conductivity for the mixture of poly(phenylenevinytene) derivatives containing ethylene oxide chain with LiClO_4 was higher than that for the mixture composed of poly(phenytenevinylene) derivatives with alkyt moiety, oligoethethyleneoxide of 1000 and LiClO_<4">

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Poly(ethylene oxide) is well known ion conductive polymer. We synthesized the main chain type and side chain type polymer with ethylene oxide chain in polymer backbone. One of the main chain type polymers exhibited nematic phase and the other exhibited smectic phase. The side chain type polymer exhibited smectic phase at the alkoxy chain length of 6. But the mixtures of polymer with lithium salt exhibited smectic phase at the alkoxy chain length of both 6 and 16. Ionic conductivity of the mixtures with lithium salt at the ratio of 0.11 per polymer repeating unit was 10^<-6>S/cm in the smectic phase (90℃) and 10^<-5>S/cm in the isotropic phase (150℃), respectively. Furthermore, ionic conductivity for the mixtures increased with increasing lithium salt concentration. We examined the Vogel-Tamman-Fulcher(VTF) parameters of these mixtures of the side-chain type polymers by fitting data to VTF equation. The activation energy of ionic conductivity in the liquid crystal phase was larger than that of the isotropic phase.

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Liquid crystalline polymer (LCP) containing carbazolyl group turned out to be hole-transporting material with relatively high performance at room temperature. In the case of LCP film fabricated onto polyimide alignment film, the director of mesogen in polymer side chain was aligned parallel to the rubbing direction of polyimide. An SHG measurement of the oriented sample clarified that the LCP film was SHG active. Second-order superpolarizability (β) originated from a carbazolyl group was aligned perpendicular to the substrate plane. Furthermore, SHG-phase measurements showed that second-order superpolarizability originated from carbazole was aligned downward against substrate plane.

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Liquid crystalline (LC) aromatic conjugated polymers such as poly(p-phenyiene)s and poly(p- phenylenevinylene)s substituted with LC groups in side chains (LC-PPPs and LC-PPVs) were macroscopically aligned under magnetic field to construct mono-domain structures. The alignments were carried out by applying the magnetic force of 10 Tesla into the polymers under LC temperatumo Analysis of aligned textures of polarizing optical, microscope and X-ray diffraction patterns indicated that LC side chains and the main chain in the di-substituted LC-PPVs are oriented parallel and perpendicular to the magnetic field, respectively. However, it is particular interest that in the case of mono-substituted LC-PPPs and LC-PPVs, both the LC side chains and even the maim chains are oriented parallel to the magnetic field. IR and UV-Vis absorption and fluorescence spectra of the aligned polymers showed optical dichroism.

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Recently, novel conjugated polymers, liquid crystalline (LC) polythienylene derivatives, were synthesized by introducing LC substituents into the 3-position of thiophene rings, to generate anisotropies in both electrical and optical properties. The polymers showed enantiotropic smectic A or B phase and fluorescence. Here, we report the magnefically forced alignment of these polymers. X-ray diffraction measurements demonstrated that the LC side chains and the main chains are oriented parallel and perpendicular to the direction of magnetic field, respectively, producing a macroscopic alignment of the polymers. The high alignment of the polymers was also confirmed from dichroism in infrared spectra. The polymers showed dichroic fluorescence with ratios of 1.5〜3.5.

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Completely separated LC and polymer layers, which are totally different from PDLCs, can be obtained by choosing a suitable combination of LC and UV polymer materials. If such the LC cell is prepared by irradiating the UV light through a photomask, we can easily make LC optical devices with a relief structure. However, the formation process and mechanism of such the layer structure have not been clear so far. In this paper, we have prepared some LC cells with the layer structure using various substrate surfaces, LC materials and UV monomers, and the observation results are investigated from the viewpoint of some material parameters.

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The composite system composed of a self-assemble low molecular weight gelling agent and a liquid crystal formed a spherulite-like aggregate upon continuous cooling from an isotropic composite. On the other hand, the spherulite-like aggregation did not exist in the composite system which was gelated by holding the isotropic composite at the temperature just below the solgel transition temperature(isothermal gelation). Atomic force microscopic observation revealed that the fiber-like aggregate of ca. 110 nm in diameter was formed in the composite system prepared by the isothermal gelation method. The composite system prepared by the isothermal gelation method exhibited the about 100 % light transmittance upon the application of an electric voltage of 25 Vrms. This indicates that the control of the cooling process is a predominant factor for the electro-optical properties for the composite system.

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A new reverse-mode light switching (transparent and opaque in undriven and driven states, respectively) has been demonstrated for the binary composite system composed of a pseudo side-chain liquid crystalline copolymer (pseudo-LCcoP) which induces spontaneous homeotropic alignment and low-molecular-weight liquid crystals (LCs). The cell with the spontaneous homeotropic alignment showed a transparent state due to a homeotropic anchoring of the pseudo-LCcoP at the surfaces of glass substrates. On the other hand, when a dc electric field was applied, the composite film became opaque due to the fluctuation of smectic like short-range order fragments being composed of the side chain part of the pseudo-LCcoP and the LCs. The light scattering state might arise from electric hydrodynamic motion of the smectic fragments an electric current effect.

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Liquid crystalline comb-shaped polymers with ionic units were synthesized by radical polymerization of mesogenic methacrylate monomers. Their phase transitions and orientational behavior were examined. The ionic unit was introduced into a spacer moiety in the side-chain. The liquid crystalline ionic and nonionic polymers showed a smectic A phase with a focal conic fan texture. The liquid crystalline ionic polymers exhibited higher phase transition points than the liquid crystalline nonionic polymers.

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Defect-free FLCDs were fabricated by using obliquely UV irradiated polyimide films. A polyimide called RN1199 which is useful for fabricating defect-free FLCDs by rubbing technique was also shown to be useful for photoalignment method, and then good memory capability of a bistable FLC cell fabricated by photoalignment was demonstrated. It was found that photoalignment was'nt at all inferior to rubbing in terms of the observation of microscopic textures and electrooptical characteristics of SSFLC cells.

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