We apply nonlinear dielectric spectroscopy to an antiferroelectric liquid crystal MHPBC at various smectic sub-phases. We report results on the dynamics of these sub-phases.

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Antiferroelectric liquid crystsls (AFLCs) composed of low-molecular mass mesogens do not show the nematic (N) phase which is important to obtain a uniform molecular orientation. Recently, it has been reported that an AFLC with dimeric molecules, may show the N phase. However, it is not obvious why the antiferroelectric chiral smectic C (SmCA*) and N phases may coexist in the phase sequence of the dimeric AFLC. In this study, the molecular alignment structure of both phases has been researched in detail with a polarized FT-IR.

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Polymer stabilization has already been studied as an attractive technique that may realize monostable ferroelectric liquid crystals with a gray-scale capability. Although the monostability can realize in a few polymer concentration for surface-stabilized FLCs, the effect of polymer stabilization on the helical structure of FLCs has not been clear yet. In this study , we reseach the effect of polymer stabilization in terms of the conoscope images obtained from the computer simulation and the experiment.

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We have investigated the deformation behavior of uniaxial-deformed smectic C elastomers during the successive transitions. In the case of an elastomer crosslinked by mesogenic crosslinkers, the smectic layers become tilted and are ordered on a cone around director, while the director stays parallel to the direction of the uniaxial deformation. On the other hand, in the case of an elastomer crosslinked by hydroquinone-type crosslinkers, the molecules become tilted with respect to the layer normal, which stays parallel to the direction of the uniaxial deformation. In addition, we discuss the relationship between chemical structure of crosslinker and deformation behavior of smectic elastomer by means of X-ray scattering observation.

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Dielectric characteristics of cholesteric blue phase (BP) have been investigated as a function of temperature, bias field and molecular alignment. Dielectric constants in the BP and cholesteric phase increased upon applying electric bias field, and especially those in the BP I and BP II was enhanced. As a result, phase transition temperatures were clearly determined by the dielectric measurement. The effect of polymer stabilization on the dielectric characteristics in the BP has also been investigated.

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The polymer stabilization is a very attractive technology because the improvement of the characteristics and the appearance of new characteristics are expected in polymer-stabilized liquid crystals. This technology has been mainly utilized to stabilize the molecular orientation up to now. In this research, we have observed the microscopic textures and measured the phase transition temperature of polymer-stabilized liquid crystal, and then report the effect of polymer stabilization on phase stability.

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The structure of the B4 phase in a bent-core liquid crystal, P-8-O-PIMB, and its mixtures with a calamitic liquid crystal, 5CB, has been observed with freeze-fracture replication electron microscopy. As a result, a novel twist grain boundary (TGB) structure with a helical pitch of about 2.5x10² nm was confirmed.

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In microscopic point of view, a decay late formulated based on a fluctuation dissipation theory is calculated by the simulation. The relaxation process of an order parameter is also obtained by the Monte-Carlo simulation of Gay-Berne particle system. The decay rates obtained by both procedures are compared for several systems with different length of Gay-Berne particles.

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Liquid crystals have been known to show the second-order electro-optical effect(Kerr effect), which caused by the electronic polarization and the orientational polarization simultaneously. Because of the high speed response, the main contribution of the second-order electro-optical effect has been believed to be an electronic polarization In this report, we studied the second-order electro-optical effect in the dye-doped liquid crystals, and we found that the main contribution of the second-order electro-optical effect was the orientational polarization.

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We prepared silica thin films hybridized with lyotropic liquid crystals by dip-coating of sol mixtures onto a glass substrate. The hybrid films were characterized by X-ray diffraction measurement and UV-Vis spectroscopy. As a result, the hybrid films had immobilized columnar assemblies of lyotropic liquid crystals. Furthermore, we achieved their in-plane orientation in a large area.

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A new hybrid type polyimide imprinting material which consists of polyester amic acid and epoxy resin is presented for a liquid crystal alignment with nano-imprinting lithography. A mold pattern is transferred clearly into the material under suitable pressure, temperature, and time conditions. This material shows excellent capability in liquid crystal alignment as well as nano-imprinting lithography. For comparison, polymethylmethacrylate was used as thermoplastic material for an LC alignment. Liquid crystal cells with this material show good electro-optic characteristics in liquid crystal devices unchangingly after thermal aging test due to its high thermal stability.

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It was recently found that the fluorination of peripheral chains in triphenylene mesogens leads to the thermal enhancement of Colh mesophase stability and gives a strong tendency of spontaneous homeotoropic alignment behavior on a variety of substrates with the increase of fluorinated chain length. In this study, the alignment behavior is discussed in terms of the surface free energy estimated by contact angle measurements of the perfluoroalkylated triphenylene films on substrates.

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In last years a photo-induced liquid crystal alignment of no-rubbing method attracts re-attention. In this research, we considered photo-induced liquid crystal alignment using organic inorganic hybrid materials. Photo-functional material was selected organic compound and polysilazane which changed to silica at heat treatment was inorganic agent. Organic inorganic hybrid polymers possess photo-controllability to give a homogeneous liquid crystal alignment upon polarized UV irradiation.

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Some novel liquid crystalline naphthalenes were synthesized and their phase transition behaviors, optical properties were investigated. The liquid crystalline dialkoxynaphthalene derivatives were synthesized from 1,5- or 2,6-dihydroxynaphthalene and 4-cyano-4'-hydroxybiphenyl with appropriate methylene chains by Williamson or Mitsunobu eterification reaction. The transitional properties observed by thermo-controlled polarizing microscopy showed that 1,5-naphthalene derivatives had a monotropic nematic phase, while 2,6-naphthalene derivatives had an enantiotropic one. They showed an intense blue fluorescence in the liquid and liquid crystalline states.

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Reductive dilithiation of PhSCH(SiMe₂SiMe₂)₂CHSPh followed by silylation with ClSiR₂SiR₂Cl (R = Et, Pr) afforded with corresponding tetraethyl- and tetrapropyldisilylene-bridged polysilacage compounds, which were found to exhibit columnar phases.

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In recent years, some liquid crystals with a bent-core structure have been investigated. New chiral compounds were synthesized using an optically active trans-1,2-cyclohexanedicarboxylic acid and some phenol derivatives. In the present study, we report the synthesis and the physical properties of the new optically active compounds.

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Quinhydrone charge transfer complex is a very interesting molecular crystal because cooperation of charge and proton transfers takes place. On the other hand, the discotic liquid crystal is known there have the one dimensional charge transfer interaction. On the basis of this, we synthesized disctic liquid crystal compounds that introduced the quinhydrone part into the pyrene molecule. Moreover, we examined characterization of qinhydrone pyrene derivatives.

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Oligomeric liquid crystalline compounds are expected to show interesting properties, because such compounds have an intermediate molecular weight between polymeric liquid crystalline compounds and monomeric ones. The oligomeric compounds, 1,2,3-tri[ω-(cyanobiphenyloxy)hexanoyloxy]propane and 3,3'-tetra[ω-(cyanobiphenyloxy)-2-propanoloxy]dipropylether were synthesized in our laboratory. These compounds have a glycerol unit as the main chin. The thermal and the dynamic viscoelastic properties of these compounds have been studied, furthermore, the electrorheological effect has been also studied.

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This paper describes synthesis and mesomorphic properties of polar liquid crystal materials incorporating a chromen-2-one skeleton at the terminal position. 4-Alkoxycinnamate derivatives (2-n) show an enantiotropic smectic A (SmA) phase, while 4-alkoxybenzoate ones (1-n) tend to show a monotropic nematic and SmA phases. The SmA-isotropic transition temperature for 2-n increases with ascending the carbon number (n). The SmA phase for 2-n were characterized using binary phase diagrams and small angle X-ray diffractions. These results will be discussed in terms of the molecular structures and electro-static nature.

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We developed new oligothiophenes exhibiting columnar liquid crystalline phases. The columnar structures could be oriented uniaxially by mechanical shearing in the liquid crystalline states.

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The pre-tilt angle is important factor for the LC display. The purpose of this investigation is to look for the design concept of the LC mixture in order to control the pre-tilt angle. In this study we focused to the neutral LC materials because the influence of neutral materials on the LC mixture of main performance is not larger than the polar materials. According to our investigation, the mixture that added the neutral material showed a difference pre-tilt angle. It was depend on the structure of the neutral material. It was found that a new design concept to control the pre-tilt angles was able to select the neutral materials.

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We report on the liquid crystalline properties of new oligothiophene-based block molecules. These compounds exhibit enantiotropic smectic A phases in wider temperature ranges.

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Rotational viscosity of binary liquid crystal mixture was calculated by an atomistic molecular dynamic (MD) simulation. We tried calculations of two approaches. One is Non-equilibrium MD calculation is that the director of nematic ensemble is forced to rotate by a special force termed aliening force. The other caluculation is when the director of ensemble is rotated, the torque is constant and accordingly it brings a steady director rotation. The test mixture is consisted of 4-(4-phentylcyclohexyl)benzonitrile (PCH-5) and 4-(4-pentylcyclohexyl)phenylbenzoate (D-55). We made a special model that the aligning force applied to just PHC-5 molecules, and the calculation value on each MD methods was cattied out. According to comparison between these MD calculations and experiments, it has been found that both approaches are useful for estimation of rotational viscosity of LC mixture.

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The chiral dopants for nematic liquid crystals with two chiral parts were synthesized from an optically active 4,4,4-trifluoro-3-{4-(4-methoxyphenyl)phenyl}butanoic acid. The solubility in the host nematic liquid crystal (ZLI-1132, Merck) and the temperature dependence of the helical twisting power values were investigated for the chiral dopants. It was found that the solubility of the chiral dopants in ZLI-1132 strongly depended on the length of the terminal chain. It was suggested that the temperature dependence of the helical twisting power values of the chiral dopants changed the ratio of the rigid structure in the chiral dopant molecule.

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We synthesized novel liquid crystalline compounds possessing fluorinated and non-fluorinated benzene rings. These molecules generated highly-ordered liquid crystal phases by using perfluorophenyl-phenyl interaction. Their phase transition behaviors were investigated by polarized light optical microscopy (POM), differential scanning calorimeter (DSC). Most of compounds in this series showed Nematic and SmecticA phases. And their structures were analyzed by powder X-ray diffractions (XRD).

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We have investigated the molecular alignment and the phase transition behavior of a mixture composed of a typical thermotropic smectic liquid crystal (4-(methylheptyloxycarbonyl) phenyl 4'-octyloxybihenyl-4-carboxylate:S-MHPOBC) and alkanes (octane and hexane). The myelin texture is observed in the mixture in the temperature range where the emergence of mesophases is confirmed by DSC. X-ray measurements show that the mesophases are smectics. While the layer thickness is thicker than 4.5 nm, it decreases with increasing temperature.

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We synthesized an optically active carboxylic acid, 4,4,4-trifluoro-3-(6-methoxy-2-naphthyl)butanoic acid (TFMNBA)[1]. New chiral dopants having two chiral centers were derived from 1*, and their helical twisting power (HTP) values were evaluated. The chiral parts and the core part were linked with ester bonds or ether bonds, and the ether type chiral dopants showed larger HTP values than the ester type chiral dopants. The chiral dopant, an optically active 4,4'-bis(4,4,4-trifluoro-3-(6-methoxy-2-naphthyl)butyloxy)biphenyl,showed the largest HTP value (32.1 um-1) in the series .

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A novel benzoic acid derivative possessing acrylate moieties was prepared and complexed with several dipyridyl compounds in the rate of 2:1. These supramolecular monomers exhibited a monotropic smectic A mesophase and the properties were investigated by polarized light optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). One of these supramolecular compounds was mixed with a crosslinker compound and photopolymerized by UV irradiation in liquid crystalline state. The polymerization proceeded with maintaining the molecular arrangement in the liquid crystal phase to give a layered sheet structure.

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Crosslinked side-chain liquid crystalline gels thin films containing azobenzene moieties were prepared by photopolymerized under visible light (436 nm) irradiation in the liquid crystalline state. The monodomain and polydomain gels were prepared on a rubbed and non-rubbed polymer film, respectively. Swelling and shrinkage in low molecular weight liquid crystal solvents were induced by the photoisomerization of azobenzene. Because the amount of azobenzene moieties were lowered to 3 wt%, the whole volume changed, and the photoisomerization behavior could be precisely evaluated by optical microscopy and UV-Vis spectroscopy.

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Nonchiral dimer alpha,omega-bis(4-(4'-buthoxyphenyl)benzylchio)perfluoroalkane was synthesized and its mesogenicity was studied by thermal, optical and spectroscopic methods. A peculiar SmA phase was observed and the relationship between molecular structure and liquid crystalline phase was discussed.

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We have newly designed and synthesized a family of copolymers containing a hexyl acrylate and an azobenzene monomer prepared at various mixing ratios. In this series, the phototriggered relief formation of the polymers could be discussed simply on the basis of their thermal properties because complicated factors such as nanophase separation and aggregation of azobenzenes are suppressed for the polymers. When the polymer films were irradiated with UV light through a photomask, the polymers migrated from dark regions to bright regions, resulting in a formation of "hill" structures. Such behavior is different from that found in our previous works.

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The purpose of this paper is to investigate the shape-memory effect of main-chain smectic elastomers. In a uniaxially deformed smectic C elastomer, the reversible deformation such as shrinkage and elongation is observed in a heating and cooling process in which the smectic-isotropic (isotropic-smectic) transition takes place. We confirmed that the strength of layer reflection becomes weak after the uniaxial deformation. We discuss not only the shape-memory effect but also the structural change under mechanical stress.

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We synthesized new type of hydrogen bonding liquid crystalline copolymers comprising photo-cross-linkable group. The copolymers showed the liquid crystalline phase by forming dimer with hydrogen bonding of carboxyl group. Axis-selective photo-cross-linking reaction of the cinnamoyl group using linearly polarized ultraviolet (LPUV) light generated small optical anisotropy, and subsequent annealing enhanced it. The enhanced in-plane order parameter is -0.7.

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The poly(alpha-trifluoromethylacrylates) bearing biphenyl derivatives with OC8H17, OCH3 and CN end groups were prepared and their mesogenisity were studied. The liquid crystal phases were observed and the influence of alpha-substituted CF3 groups on the mesogenisity was compared with acrylate, methacrylate, and alpha-fluoroacrylate polymers having the same side groups.

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New supramolecular liquid crystals have been designed and synthesized by incorporating pyridinium and imidazolium ionic moieties into lipophilic moieties bearing glutamic acid platforms. These ionic molecules self-assemble through non-covalent interactions to form thermotropic columnar liquid crystals. FT-IR, UV-Vis, CD studies, and X-ray diffraction measurements reveal the formation of chiral columnar assemblies, reflecting the molecular chirality of the glutamic acid moieties.

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In this study, ambipolar charge carrier transport properties were investigated for a homologous series of hexaalkoxytriphenylene (CnOTP) by time-of-flight (TOF) technique for the homeotropic domains. Ambipolar electronic charge carrier transport was observed and the both positive and negative charge carrier mobilities decrease with the increase of the alkyl chain length. Ionic conduction was also observed for the negative charge carrier transport except for C4OTP and any remarkable dependency of the alkyl chain length was not seen. It was reasonably found that both the positive and negative charged carrier mobilities by electronic hopping process is affected by the intra columnar order.

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Unsymmetrically 1,1'-disubstituted ferrocene derivatives have two different substituents at 1 and 1' positions. The unsymmetrical derivatives were systematically prepared with changing the number of benzene ring in the mesogenic groups. In addition, symmetrically 1,1'-disubstituted ferrocene derivatives were prepared in order to compare the phase transition behavior of these compounds with those of the unsymmetrical derivatives. The phase transition behavior of objective compoumds was studied by a differential scanning caloriemetry measurement and a polarizing microscopy observation, and the relationship between the structure and the temperature range of liquid crystalline phase was discussed.

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We synthesized novel benzoic acid derivatives which generate complexes with compounds possessing pyridine moieties. The complexes exhibited a columnar liquid crystal phase. We investigated its liquid crystalline behavior and superstructure by polarized light optical microscopy, DSC and powder X-ray diffractions. Further the supramolecular compound was polymerized by UV irradiation (365nm) in the liquid crystal states and we attempted to form a tubular nano-structure by removal of the pyridine derivatives from the central part.

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Ionic liquids have attracted much attention as a new generation of ion-conductive materials. For example, ammonium salts containing perfluorinated anions are representative molecules that form ionic liquid. In the present study, we have developed liquid crystalline ammonium salts having block structures composed of fan-shaped lipophilic and ionic parts. Self-assembly of these molecules through nano-segregation and ionic interaction leads to the formation of low-dimensional ion-conductive paths in the liquid crystalline states.

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Novel liquid crystalline ureas were the synthesized and characterized. Their compounds were composed of the two long core units. The mesophase was characterized by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and switching experiments. The X-ray diffraction studies revealed a hexagonal columnar structure in the mesophase. The switching experiments indicated a ferroelectric polar switching for the hexagonal phases. However, after switching off the applied voltage, the polarity was disappeared with the relaxing-back.

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Recently, the temperature range of blue phases was successfully extended to more than 100 K in polymer/liquid crystal composite systems. However, the mechanism of stabilization is not understood yet. In this study, the twin type molecule with two characters, liquid crystal nature and non-liquid crystal nature, was newly synthesized, and it added into blue phases. Such the molecule can be expected to stabilize the interface between the ordered region and the defect in BP. The influence of the addition of the twin type molecule on the temperature range of blue phases was investigated.

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[in Japanese]

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The high precise polarization microscopy in OCB-mode liquid crystal cell was carried out with the aim of ensuring and speedup of splay-bend alignment transition. The following were discussed: transition mechanisms from the splay alignment to the bend alignment, effects of the post spacer, frequency dependence and voltage dependence for the transition time, voltage dependence of the molecular orientation, and effects of which applied various waveform voltages. As the results, useful knowledge on ensuring and speedup of splay-bend alignment transition were obtained.

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Optically compensated bend (OCB) mode device exhibits fast response and wide viewing angle. In the OCB mode device, side-chain type polyimide have been used as a alignment layer since high pretilt angle is required. The amount of the side chain changes the surface structure of the polyimide alignment layer, and has an influence on the device properties. In this study, we have been prepared various polyimides and investigated the effects of the polyimide alignment layers on the rate of splay-bend transition and the response.

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The practical application of one drop fill (ODF) method has shortened the manufacturing process of liquid crystal display and has been able to prepare large panels. We have investigated the flow and orientation behaviors of liquid crystals during the glass-substrate assembling process of the ODF. In this study, we have investigated the influence of polyimide alignment layers with different chemical structures on the flow behaviors and drop-mark formation of liquid crystals during the glass-substrate assembling process. The drop mark was observed on polyimide layers with low substitution ratio of side chain after assembling. On the other hand, no drop mark appeared on rubbed polyimide layers.

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The optically compensated bend (OCB) nematic liquid crystal display (LCD) has attracted much attention due to its superior characteristics such as a fast response time and a wide viewing angle. The OCB-type LCD has one serious drawback in that it needs the initial transition operation from the splay alignment to the bend alignment by applying high voltage at start-up, and always needs an operating voltage higher than its critical voltage to maintain the bend alignment. To mitigate this problem, polymer stabilized method have been proposed. This research investigated the transient response characteristics of the polymer stabilized pi cell. The transient response speed of the pi cell being in the bend alignment decreased by polymer stabilization. The transient response speed depended on the UV irradiation energy.

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The optimum azimuthal angles of the transmissive axes of polarizer and analyzer to obtain the maximum contrast ratio are theoretically investigated for a Bi-Nem type LC cell. The results from this theoretical investigation are compared with the experimental results. Based on the liquid crystal continuum theory, the director profiles are theoretically calculated for the U state and the T state, taking into account the anchoring effect on each substrate surface. Jones matrix method has been used to calculate the transmittance for the U and T state of the Bi-Nem cell. The calculated results are compared with the experimental results.

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We have developed an A4-sized ferroelectric liquid crystal (FLC) displays using a flexible backlight sheet. The flexibility of backlight was obtained by combination of side light of three-primary-color LED chips and a flexible-polymer thin light guide plate. A plastic substrate with low thermal distortion was adopted and a compounding ratio of liquid crystal and monomer was adjusted to improve the molecular alignment of a composite film of the FLC and fine polymer fibers near polymer walls. Color moving images were displayed on a flexible screen by driving with an active matrix technique using external switch transistor array based on a field-sequential-color method.

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In our previous paper, a theoretical model had been proposed for the movement of particles in the MFPD (Mobile Fine Particle Display). Furthermore, based on the model, the expression for the moving velocity of particles along the parallel direction to the substrate surface had been driven taking account of Coulomb's force, the dielectric force and the viscous force acting on particles. In this paper, the validity of theoretical model and the theoretical expression for the velocity has been experimentally investigated and confirmed using a several kinds of nematic liquid crystal having different values of dielectric anisotropy and viscosity.

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High-speed electrooptic switching based on the tunable defect mode in a one-dimensional photonic crystal containing a nematic liquid crystal defect layer has been demonstrated. The switching originates from the narrow spectral linewidth of the defect mode. The optical properties of the defect mode switching are also analyzed. The electro-optic responses of the switching device are calculated considering director distributions in the defect layer which are determined using a continuum theory. The defect mode peak shifts with increasing the applied voltage. The rise time of the defect mode switching is in the order of microseconds at high voltage. The decay time based on molecular relaxation is also fast as the order of microseconds. The calculation results agree with the experimental results.

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