An experimental investigation with DSC has been made for the solvent effect of 5CB. The concentration vs. T_NI curves for the aprotic solvents with 5CB is drop down more drastically than that for the protic solvent systems. Further, in order to argue the interaction between the 5CB and solvent, we studied the electronic state of 5CB in aceton and methanol by means of the solid state NMR.

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Depressions in the N-I transition temperature of 4-(4-alkoxybenzylidene-amino)phenyl benzoate and N-[4-(4-alkoxybenzoyloxy)benzylidene]aniline by the introduction of a lateral methyl or chloro group into the benzoate moiety of the former compound or the aniline moiety of the latter have been examined. In contrast to the view expressed by Gray et al., our results strongly suggest that the nature of the terminal substituent is as important as the size of the lateral substituents and/or the steric hindrance determining the transition temperature.

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Liquid crystalline binary systems were prepared by mixing twin compounds. The twin compounds formed only a nematic phase. The liquid crystalline binary system consisting of the twin compounds(even-members) with even-numbered central methylene units showed nematic and induced smectic A phases. However, the liquid crystalline binary system having the odd-members exhibited an induced smectic C phase, which was characterized by broken fan and schlieren textures and the X-ray wide-angle halo, in addition to a nematic phase. This difference can be related to the conformation of the twin liquid crystals.

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Liquid crystals having hydroxyl and ionic terminal units were synthesized and their thermal properties and orientational structures were examined. Coulombic force and hydrogen bonding acted effectively, in forming liquid crystalline phases and enhanced the thermal stability.

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Hydroxo[5, 10, 15, 20-tetrakis(4-n-dodecylphenyl)porphinato]aluminium(III) is found to exibit D_hd mesophase, whilst the another square planar metalloporphyrins analogues show only mesophases of lamellar type. It was indicated the axial OH group could significantly contribute to formation of stacking columns. But the phase transitions of the homologues revealed that the alkyl chains also take part in the mesomorphic behaviour as such that the heptyl derivative showed different phase sequence from that of the dodecyl and hexadecyl ones.

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It was revealed that change of the absorption and fluorescence spectra through the mesomorphic phase transitions of a long-chain tetraphenylporphyrin is likely to reflect change of the molecular orientational order such as the presence or absence of molecular stacking structure. The fluorescence excitation spectra showed the evedence of band splittings in Q-band and two splitted peaks contibute to two fluorescence peaks at ca. 650 nm and ca. 720 nm in different way for each.

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The importance of the interlayer molecular interaction to stabilize the antiferroelectric smectic C_A^* (SmC_A^*) phase is shown using dimer molecules in which chiral mesogenic units are connected by a polymethylene chain. According to the conformational effect of the polymethylene chain, two mesogenic units tend to align parallel or anticlinically depending on the carbon number, even or odd, respectively. In a dimer molecule with a longer chain length, however, the other interaction overcomes the conformational effect and stabilizes the SmCA^* phaec. This observation suggests the importance of the electric, possibly the dipole-dipole, interaction between mesogens in SmCA^*.

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Smectic layer reformation from chevron to quasi-bookshelf structures by strong AC electric fields and accompanying changes in physical properties were examined. Layer reformation took place at a threshold value of the amplitude, and the spontanious polarization (Ps) and the apparent tilt angle (θ) show a stepwise change. The absolute values of Ps and θ in the cells ticker than 10μm are independent of cell thickness, but in the cells thinner than 10 μm, are decreasing with decreasing cell thickness. The experimental results were discussed on the basis of surface freezing layers.

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The local layer structure(LLS) at the narrow wall (lightening) of the zigzag defect in surface stabilized ferroelectric liquid crystals was characterized using synchrotron X-ray micro-diffraction. An X-ray beam size used was 5 μm or 2.5 μm. A liquid crystal used was CS1014. The diffracted intensity was measured as functions of θ, χ and Y(position). At the narrow wall running parallel to the rubbing direction, the LLS was a pseudo- bookshelf structure with an angle of 16° between the layer normal and the rubbing direction. The bookshelf structure also bent in the θ direction. At the inclined narrow wall, the LLS showed a larger bend in θ direction as well as the inclination in χ direction. The layer normal made a larger angle with the rubbing direction.

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We have investigated a field induced phase transition between SmC^* and SmC_A^* in a three-component mixture of ferroelectric and antiferroelectric liquid crystals characterized by trifluoro-alkoxyalkyl carboxylate and partially fluoro-substituted phenyl rings. We encountered a system where a pretransitional effect is enhanced and a threshold becomes zero so that the field induced F-AF-F phase transition looks like a V-shape switching. In this phase, it is possible that molecular tilting direction is non-correlated between adjacent layers; tilting randomization among smectic layers assures the disappearance of net spontaneous polarization, but an applied electric field induces it according to the Langevin-type equation. We propose to designate the phase with thresholdless antiferroelectricity as SmC_R^* with subscript R meaning random.

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High precision measurements of mass density and layer thickness were carried out in antiferroelectric liquid crystal 4-(1-methylhepthyloxycarbonyl) 3-fluorophenyl 4'-dodecyl-biphenyl-4-carboxylate(MHFPDBC). Density anomalies were discovered at Iso.-SmA and SmA-SmC^* transition temperatures. However, no anomaly could be find in any other transition temperatures. On the other hand, the layer thickness showed an anomaly only at the SmA-SmC^* transition temperature. At any other temperature, no jump or change in the layer thickness could be confirmed within the experimental accuracy. From above results, the pairing of dipoles was thought to be sufficiently weak in this antiferroelectric liquid crystals.

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Smectic layer rotation in antiferroelectric liquid crystals upon application of asymmetric pulses of electric field has been investigated. The rotation angle of smectic layer increases with increasing the number of pulse trains and is more than 60° away from the initial alignment axis. The rotation angle is proportion to the number of pulse trains below 20° and in this range the uniform alignment is maintained. This smectic layer rotation is reversible and the layer rotates in the opposite direction upon application of pulses of electric field with opposite polarity. This smectic layer rotation has been interpreted in terms of the difference in domain nucleations between ferroelectric-antiferroelectric and antiferroelectric-ferroelectric phase transition.

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In order to investigate the structure in the SmCγ^* phase, we measured the small angle X-ray diffraction by using the synchrotron radiation. We observed the diffraction peak corresponding to the three times of the layer spacing, and it indicates that the structure in the ferrielectric SmCγ^* phase has a unit of three layers, as suggested so far.

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We have studied the propeties of antiferroelectric liquid crystal of rasemic tetralin compound. In this work, Chiral tetralin antiferroelectric liquid crystals were synthesized and show different phase and response time between R form and S form.

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The series of alkylsilyl ether substituted pyranose derivatives with fluoro-alkyl group were synthesized for the chiral dopants of ferroelectric liquid crystals. Compared with the alkyl ether substituted ones, they induced larger spontaneous polarization(Ps). But other properties, such as phase transition temperature, tilt angle, were same as those of alkyl ether substituted ones. In the series of alkylsilyl ether substituted group, trimethylsilyl substituted one had the largest Ps and higher S_C^*-S_A transition temperature.

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Two new series of ferroelectric liquid crystals with a trifluoromethyl group at the chiral center were synthesized utilizing optically active 3-trifluoromethylalkanoic acid prepared by optical resolution procedures, their mesomorphic and physical propertics (phase behavior, spontaneous polarization and response time) were investigated. All of the new ferroelectric liquid crystals exhibited ferroelectric smectic C^* phase in a wide temperature range and were found to possess a large spontaneous polarization value.

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Optical rotatory power(ORP) and circular dichroism(CD) measurements were made to investigate helical structures in antiferroelectric liquid crystals. The antiferroelectric liquid crystals used were MHFPDBC(n=12), MHFPUBC(n=11) and MHFPHBC(n=7) of different in alkyl chain length. The experimental results of ORP and CD showed that the alkyl chain length is an important factor for stabilizing the helical structure. In the ferrielectric SmC_γ^*, which had a long helical pitch, the CD spectrum showed a high absorption peak due to π-π^* transition. The ORP obtained from CD spectrum using Kramers-Kronig formula was discussed in comparison with the experimental results of ORP.

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Dimeric liquid crystals of general structure [(S)-n-C_mH_2m+1OC₆H₄C₆H₄COOC₆H₄COOCH(CF₃)]₂ (CH₂)_n(m = 8, 10; n = 7, 9, 11) prepared from (S)-(trifluoromethyl)oxirane exhibited stable SmC_A^* phase and were shown to be good dopants for antiferroelectric liquid crystals.

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Partially deuterated MHPOBCs(chiral part:^*C-D, C-D₃, C₆-D₁₃) have been synthesized and investigated the infrared polarized properties of above alkyl groups and the C₈H₁₇ group of achiral part.

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Several homologues of semifluorinated liquid crystals, 4'-[(n-perfluoroalkyl)alkyloxylphenyl 4-(2-fluorooctyloxy) benzoates and 4'-(2-fluorooctyloxy)phenyl 4-[(n-perfluoroalkyl)alkyl oxy]benzoates have been synthesized. One set of the compounds with their central carbonyl group being conjugated to the terminal position carrying the nonchiral perfluoroalkyloxy tail showed enhanced chiral smectic C mesophases, while the other set with their central carbonyl group being conjugated to the terminal position carrying the chiral 2-fluorooctyloxy tail presented enhanced smectic A phases. The mesomorphic properties of these novel fluorinated materials are reported and the effects of fluorination extent are discussed.

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Novel chiral twin molecules, (S)-2-methylnonanedioic acid bis[4-(5-octyl-2-pyrimidinyl)phenyl]ester (MNB-8-PYP) and (S)-2-methyldecanedioic acid bis[4-(5-octyl-2-pyrimidinyl)phenyl]ester (MDB-8-PYP), have been prepared and the odd-even effect of the chiral spacer on the helical twisting power investigated. Pitch measurements in a mixture with a host material revealed that MDB-8-PYP with an even number of atoms in the spacer induces a stronger helical structure in the cholesteric phase and particularly in the chiral smectic C phase than MNB-8-PYP with an odd numbered spacer. The marked odd-even effect observed in the SmC^* pitch can be explained by our proposed "intercalated chirality" model for twisting power in smectic phases induced by a chiral twin molecule.

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The S_C^* phase is induced by chiral dopants. Therefore, the chiral dopants strongly affect the phase behavior of the resulting ferroelectric liquid crystals(FLCs). In this study, we synthesized a photochromic chiral dopant containing an azobenzene moiety and investigated the FLC behavior of the mixture of the chiral dopant and host LC. We further explored the photochemical switching behavior of the mixture by steady-state and time-resolved measurement. We found that trans→cis photoisomerization of the chiral dopant effectively caused disappearance of the S_C^* phase and cis→trans back isomerization restored the S_C^* phase.

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A mixture of an antiferroelectric crystal(AFLC) with tetralin structure and a ferroelectric liquid Crystal(FLC) indeces an unidentified phase (designated as SmX) and the novel electrooptical response under triangular waves in the SmX phase was observed.

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Liquid crystals of phthalocyanines and their analogues have been demonstrated to be particularly attractive materials due to their extended two-dimensional π-conjugated electron system and their ali9nment in one-dimensional columnar stacks. We report here the synthesis and mesophase structures of octakis(3,4-dialkoxyphenyl)-tetrapyrazinoporphyrazinato metal(II) complexes, 1, and their corresponding ring-closed complexes, 2, with a widely extended core peripherally bearing sixteen n-alkoxy chains. All of them exhibit columnar mesophases. Interestingly, the mesophase structures of Complexes, 1, are strongly related to the structures of the aggregates in solvents. Complexes, 1, have a very rare structure of "slipped-roof-top-shaped dimer" in both the n-hexane solution and the D_hd columnar mesophase, whereas Complexes, 2, do not have such a unique structure.

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It has now widely been used the polyimides for LCD aligner. One of the most important factor for LCD is control of the pre-tilt angle of LC. But it is not clear the relationship between the pre-tilt angle of LC and the structure of the polymer aligner. The objective of this study is to synthesize the polyimide of high per-tilt angle. The side chain polyimides substituted by mesogenic or perfluorinated alkyl group showed the pre-tilt angle of 2 to 50°. The pre-tilt angle also effected the structure of the main chain group. Those results are agreed with the calculation by MOPAC.

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Sidechain-type liquid crystalline polysiloxane(SLCSs) diluted with polydimethylsiloxane(DMS) show a large increase in viscosity upon application of an electric field. We have investigated the solvent effect upon the ER behavior. When the weight fraction of DMS in smaller than 10%, the shear stress of the mixture of SLCS and DMS is nearly constant and the increase in the shear stress by the implication of an electric field is very small. With increasing the DMS's weight fraction, the zero-field shear stress drastically falls to generate a large contrast between the shear stresses with and without an applied electric field. ER effect of a SLCS employing phenyl substituted DMS as a solvent is smaller than that employing DMS. The ER effect of the SLCS decreases with increasing the phenyl content of phenyl substituted DMS. These results suggest that the phase separation between the SLCS and solvent is responsible for the generation of ER effect.

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Recently, a large electrorheological effect(ER-effect) has been reported in side-chain liquid crystal polymers by Inoue et al. However, the mechanism of the ER effect is not yet known. In the present study, the fundamental physical properties of the specimens, both the pure polymer and the diluted polymer, have been investigated by means of X-ray diffraction, dielectric measurement and microscopic observation of the texture. On the basis of these results, the mechanism of the ER effects will be discussed.

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Differential scanning calorimetric, X-ray, dielectric and dynamical mechanical studies have been made for the copolyesters composed of quaterphenyl (DHQ, hard segment) and polyethylene adipate (soft segment) to clarify the structure and phase transition. It was found that the crystalline region of the soft segment disordered by the hard segment melted near 280K and became smaller with increasing the DHQ content. The hard segment moiety was found to soften above 320K.

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The polymer morphology in Polymer Stabilized Cholesteric Textures(PSCT) film were investigated by the direct observation with scanning electron microscopy(SEM) in order to clarify the relation between polymer morphology and and electro-optic properties of the PSCT film. The SEM photograph revealed that the polymer morphology consisted of spherical particles with submicron order diameter, which three-dimensionally networked each other. The results indicate that the particle diameter and network density varied with the polymerization process and determining the electro-optic properties of PSCT film. It is noted that the polymer morphology with the large particle diameter and low network density was formed by low power and long term UV radiation process, giving to the film with the good electro-optic properties, i.e., low driving voltage, narrow hysteresis width and high contrast ratio.

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We have developed novel UV curable liquid crystals having isotropic - nematic - smectic A phase sequence and studied the photoinitiated polymerization of the liquid crystals at the state of their uniaxially oriented smectic A phase at room temperature. The optical phase retardation of the smectic A layer decreases rapidly just after the initiation of photopolymerization and decreases gradually after that. The constant value of the optical phase retardation was obtained by the aging at 150℃ for 20 minutes after photopolymerization. The polymerized film is optically uniaxial and transparent without light scattering.

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Diffusion and orientation of monomers generally influence the polymerization behavior. In order to explore the effect of orientation on polymerization behavior, the liquid-crystalline vinyl monomer was synthesized which exhibited antiferroelectric, ferrielectric, ferroelectric, smectic A, and isotropic phases. Monomer was polymerized with benzoin as a photoinitiator at various temperatures. Photoirradiation was carried out in a cell which was composed of glass substrates with ITO electrodes. The cells were made with 20 μm spacings where the inner surfaces were washed and 2 μm spacings where the inner surfaces had been coated with a polyimide aligning agent and unidirectionally rubbed. The course of the polymerization was followed by gel permeation chromatography. It was found that the conversion in smectic A phase in 20 μm cell and ferroelectric phase in 2 μm cell under applied electric field was highest in the two types of the cells. Liquid-crystalline properties of produced polymers were also investigated.

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In the study, we synthesized poly (arylene ethynylene) type polymers containing a mesogenic group in the side chain. Their mesogenic polymers improve their orientation and consequently, it would be obtained a higher order of physical value such as electric conductivity and nonlinear optical properties. The mesomorphic properties of the polymers were examined by DSC and polarized optical microscopy. Transition temperature varied remarkably with a kind of side chain. The polymers incorporated mesogenic group at the side chain into aryl groups exhibited enantiotropic nematic phase, and the optical texture was frozen at room temperature. All polymers were soluble in organic solvent such as chloroform, toluene, THF, DMF. Growing the π-conjugated length was supported by UV measurement.

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In-Situ photopolymerization of a liquid crystalline monomer in their oriented state can be produced highly oriented polymers. In this study, we synthesized diacrylate, monoacrylate, and chiral compounds containing a mesogenic group in order to obtain liquid crystalline monomeric mixtures. The chiral compounds exhibited cholesteric phase. All monomeric mixtures containing chiral compound exhibited cholesteric phase. In the presence of photoinitiator and p-methoxyphenol, monomeric mixtures were photopolymerized by UV irradiation at the liquid crystalline phase in the glass cell provided with uniaxially rubbed polyimide layers. Thermal stability of the texture for the polymer depended on the ratio of diacrylate in monomeric mixtures and kinds of chiral compounds. Especially as for the chiral compound containing acrylate group in its end group, its texture was maintained up to 300 ℃.

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In this work, we synthesized thiophene containing mesogenic group or alkyl side chain in its 3-position in order to increase solubility and softness. Copolymers were obtained by dehalogenation polycondensation with zero value nickel, organometal complex, as catalyst, and examined their phase transition behavior and electrochemical properties. It was identified that the liquid crystallinity of the polymers depended on component ratio of mesogenic monomers. The Polymers containing mesogenic monomers over 90mol% exhibited nematic phase, while any typical liquid crystalline texture did not show for the polymer consists of 80mol% mesogenic monomers. The polymers were identified that they were electrochemically active.

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This paper describes thermal properties of some poly- ω- [3-{4- (alkoxyphenoxycarbonyl) phenoxycarbonyl}phenoxy]alkyl acrylate (compound 3). Compound 3 is very interesting in connection with the correlation between the molecular structure and liquid crystalline properties. All the members show one or two kinds of smectic phases having a focal conic texture except for the ethoxy member. The structure in the smectic phases was investigated by the X-ray diffraction.

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Polymers and model compounds composed of terphenyl analogues of 1, 3, 4-thia- and oxadiazole compounds were synthesized and their thermotropic liquid crystalline(LC) properties were evaluated. The model compounds of 1, 3, 4-thiadiazoles showed stable smectic or nematic phases and had high phase transition temperatures. The 1, 3, 4-oxadiazoles exhibited lower transition temperatures and less stable nematic phases than the corresponding 1, 3, 4-thiadiazoles. Most of the polymers showed no LC melts. Only the thiadiazole-containing polymers from the dicarbozylic acid with ester linkage formed nematic phase.

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Side-chain liquid-crystalline polysiloxanes containing acetoyl terminal group, Poly [n- {4- (4- (acetoyl) phenoxycarbonyl) phenoxy}] alkoxyl methyl siloxane, were prepared with different spacer length (n=3〜6). Phase transition and fine structures of these polymers were investigated by DSC, polarizing optical microscope, and X-ray diffraction methods. Glass transition and clearing temperatures of PAS-n samples indicated odd-even effect. Smectic A phase was observed in each sample, and layered crystal were formed in PAS-5 and PAS-6. The unit cell of layered crystal of PAS-6 showed orthorhombic form with the lattice parameters a=0.79nm, b=0.54nm, c=2.70nm.

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PBLG liquid crystalline solution was confined to a sandwich cell and applied a D. C. electric field parallel to the cell surface. The appearance of regular stripes perpendicular to the D. C. field was observed after inverting the field direction by a polarizing microscope. In order to pursue the mechanism reversing the molecular director, the measurement of optical transmittance under crossed polarizers was carried out through the rotatory process to a perfect reversal of the director. The apparent activation energy of rotational viscosity was obtained from the temperature dependence of the inversion rate.

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The two dimensional orientation and/or morphology of PBLG(Polyl(γ-benzyl L-glutamate)) forming a lyotropic liquid crystal in a specific concentration range were investigated. The solution of PBLG was spread on the water surface as a monolayer and after compression to the required area, the time dependent behaviors of surface pressure and orientation of it at the constant area were examined. The solution of PBLG (Mw = 20100) / 1, 2 - dichloroethane (conc. 4.6*10^-3) was used as the spreading solution. π-A isotherm consisted of three parts, of which a plateau appeared in the middle. In this region, the surface pressure kept at a constant area decreased gradually with time. At any required period, the monolayer was transferred onto a slide glass and the texture was examined by means of AFM. By analyzing AFM images, it was confirmed that the decreasing process of surface pressure included not only the two dimensional reorientation but also the three dimensional molecular assembly. The size of the assembly depended on the initial concentration of PBLG on surface, mol / area.

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We have investigated the alignment capability of PDiPF-LB films for nematic liquid crystal (5CB) by measuring the order parameter of dichroic dye doped NLC. As a result of the measurement, we confirm that the alignment capability of a PDiPF LB-film is about 95% compared to that of rubbed polyimide film. We claim that PDiPF-LB film is useful for aligning NLC in spite of that the aligned phase of NLC is some what complex compared to that of rubbed cell. Some discussion of alignment mechanism will be given.

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We are studying the structure of straight type flagellar filament using X-ray fiber diffraction method. Highly oriented flagellar filament sol is required to achieve high resolution analysis. Making sols in liquid crystalline phase fulfill this purpose. We searched for appropriate conditions under which flagellar filament sols form a liquid crystalline state and obtained the following conclusions: 1. Average flagellar filament length must be around 300nm; 2. pH close to pI is more preferable for highly ordered liquid crystal; 3. Presence of more than 10mM salt is necessary.

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We have already reported the novel method to produce gray-scale properties in SSFLCs by using FLCs containing ultra-fine particles. This time, we have observed the broadening of polarization reversal current peak with the addition of particles, which coincided with the result of computer simulation based on the distribution of smectic layer tilt angles.

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We have produced prototype TFT-LCD using Surrounding-Electrode method with inorganic alignment layer which rubbed SiNx and so on. These alignment layer is low pretilt-angle, almost 0 degree, available to applied on the Surrounding-Electrode method. These alignment layer is deposited layer, decreasing short-type defects between TFT substrate and counter electrode substrate and on the surface of TFT substrate, and further, enabling to omit TFT passivation. This time, we have evaluated inorganic alignment layer of alignment condition, pretilt-angle, display characteristics and so on.

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Scattering light outputted from polymer dispersed LC layer is reflected by the boundary surface of the glass substrate in contact with air, so as to return to PDLC layer. Thereby this return light results in rise of luminance of a black display portion, so contrast ratio lowers. Besides we think that the return light enters the layer of semiconductor of thin film transistor so photo conductor phenomenon occurs in case of using PDLC panels for Video Projection System. We suggested that the transeparent plate is optically coupled with an output side of the PDLC panel through the transparent body. The present paper describes the Optical Coupling(OC) technology enable to reduce the return light and lower photo conductor phenomenon.

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The voltage holding ratio is one of the most important properties of liquid crystals for AM-LCD application. Fluorinated compounds with different core/side structures have been developed, and lead to high voltage holding ratio comparing with cyano compounds. The change of transmission by residual voltage have influence on image quality. In this paper, the relation between the voltage holding ratio, the change of transmission by residual voltage and chemical structures of fluorinated compounds is discussed.

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The computer simulation by modified Berreman's one viscosity model shows that "rise delay time" for TN-LCD is proportionate to not only the viscosity, but also the logarithm of inverse of pretilt angle.

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To obtain the viewing angle characteristics of a TN-LCD with optical compensators, the Jones matrix method was applied to oblique directions. The method was employed to optimize the optical compensators, taking contrast and grayscale capability into account. In this paper, an optical compensator comprising two layers is proposed. One layer has negative birefringence and an oblique optical axis, and the other has negative birefringence and a vertical optical axis. As the result of the optimization, the TN-LCD sandwitched by these compensators exhibits excellent viewing angle characteristics.

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An optical film with a negative uniaxial structure or modified negative uniaxial structure was prepared. These films improved the viewing angle of a thin film transisotor(TFT) addressed twisted nematic liquid crystal display with a normally white mode.

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Amorphous twisted nematic-liquid-crystal display(a-TN-LCD) has excellent viewing angle characteristics and is fabricated by non-rubbing method. In this LCD, it is necessary to be injected LC molecules into the cell in the isotropic phase in order to avoid the flow alignment. However, this injection method has various problems in the preparing process, then, it is desired to obtain the amorphous orientation by using the conventional injection method that is done at the room temperature. We found that the a-TN-LCD can be prepared by annealing at the high temperature which makes remove the memory effect. In addition, we will report the relation between the preparing conditions and LC molecular orientation, and electrooptical characteristics.

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In recent days the display quality of the color STN LCDs was improved so much that they are used for Note Book PCs. However, one of the display characteristics which need to be improved is a Flicker phenomenon. We have investigated the correlation between the LCD module operation condition and flicker characteristic with respect to frequency, intensity. And we've got a guide line of the module operation condition and panel characteristics to reduce the flicker.

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