We have measured the polarized infrared (IR) absorption spectra of polyimide films irradiated by linearly polarized ultraviolet (UV) light as a function of the irradiation energy. To analyze the anisotropic decomposition of the polyimide film, we employed an IR absorption band assigned to the C-O-C asymmetric stretching vibration of polyimide. It is polarized along the polymer chain. The IR dichroic difference increases up to 120 J/cm², and decreases beyond this energy. The dichroic difference is defined by A_⊥-A_//' where A_⊥ and A_//' are the absorbances for the IR light polarized perpendicular and parallel to the polarization direction of UV irradiation light, respectively. The liquid crystal (LC) molecules sandwiched by UV-irradiated polyimide films in the range from 60 to 120 J/cm^2 align homogeneously with the comparable quality to a LC cell made with rubbed polyimide films. We compared the sturface order parameter of polyimide chains in a polyimide film exposed to UV light of 120 J/cm² with that in a rubbed film. We found that the anisotropy of the polyimide film induced bv UV light irradiation is much smaller than that induced by a rubbing treatment.

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A octaoctadecylthiophthalocyanine and the Cu(II) and V=O(IV) complexes were synthesised and investigated on the mesomorphic phase transition behaviour. All these compounds exhibit discotic hexagonal disordered columnar (Dhd) mesophase. The clearing points were strongly dependent on the central metal species and the order is in V=O > Cu > metal-free, although the melting points do not show any marked difference at the temperature around 50℃. This indicates the presence of specific intermolecular interaction derived from the metal species in the mesophase.

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As a part of our continuing effort to clarify the structure-property relationship for metal-salicylaldimine mesogens, series of copper(II) complexes of N-salicylideneaniline derivatives carrying either 4-decanoyloxy or 4-octadecanoyloxy substituents on the N-phenyl groups have been prepared and characterized for their smectogenic properties. It is shown by the comparison of phase incidence for these and related series of complexes reported previously that the relative stability of tilted smectic C phases (over A) is lowered upon coordinating the corresponding ligands. The smectic layer distances for the complexes are similar to those for the ligands, and the difference in topological arrangement of the polar groups has been related to the relative weakness in the molecular tilt for the former.

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Hexakis (4-(3',4'-didodecyloxy)phenylmethoxy) cyclotriphosphazene(HDPCP) and hexakis (4-(3',4',5'-tridodecyloxy) phenylmethoxy) cyclotriphosphazene (HTPCP) were synthesized. Their phase transition and mesogenicity were studied by DSC and X-ray powder diffraction measurements and polarizing microscope observations. A monotropic discotic liquid crystalline phase was observed in HTPCP, but no mesophase was observed in HDPCP.

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Hydroxo[5,10,15,20-tetrakis(4-n-dodecylphenyl)porphinato]aluminium(III) was found to exhibit D_hd mesophase,while the another square planar metalloporphyrins anologues show only lamellar type mesophases, and it was indicated the axial OH group could significantly contribute to formation of stacking clomns. In this work, it was shown that the phase transitions of the homologues (C₇ - C₁₀) strongly depend on the alkyl chain length. Especially, mesomorphism of the μ-oxo-dimer derived from the monomer Al(OH) complex is likely to drastically change with the alkyl length, the heptyl, octyl and nonyl derivatives showed different phase sequence from those of the decyl,dodecyl and hexadecyl ones.

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One of the origins of the successive phase transitions of chiral smectics is the head-tail distinction of a molecule. In this study, we consider a molecular theoretical model to discuss the successive phase transitions. In addition to the head-tail distinction, repulsive hard core interaction between molecules is considered. Then the contribution of the mutual excluded volume effect between molecules to the successive phase transitions is examined. Assuming that the tilt angles of molecules are uniform, we discuss mainly on the distribution of azimuthal angles of molecular tilts.

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The phase diagram of the ANNNI model with the third nearest neighbour itatertrction in the electric field is studied to discuss successive plase transitiouas appearing in ferro- and antiferro-electric smectic liquid crystals. In some case, a jump of the order parameter becomes small, but the transition should be of first order in the absence of the electric field. An instability line of the ferroelectric phase, which shows the instability of the uniform phase, is also studied. The phase diagrams suggest that structures of the intermediate ferrielectric phase FI_H and FI_L are respectively of the wave number 2/7 and 2/5.

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In the ferro- and antiferro-electric smectic liquid crystals the molecules tilt in a helical plane, whose state are expressed in terms of the Ising spin, though the molecules could be expressed by the XY model. The Ising model and the classical XY model with frustrating seocnd nearest neighbour interaction in an axial direction are known to have different properties to each other even quahtatively. The XY model exposed to the symmetry breaking field with twofold symmetry is introduced here, which is reduced to the Ising model, that is, the ANNNI model in a limit of the strong field strength. The ground state of this model is examined, in which the freedom of the XY spin is shown to be suppressed at rather small strength of the symmetry breaking field and accordingly the Ising properties dominate in large area on an interaction parameter versus field cliagram, while XY-like freedom survives only at an area with weak field. This result seems to explain why the successive phase transitions observed in ferro- and antiferro-electric smectics can occur.

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We have investigated coupling between two internal order of the complex fluid mixture, which consists of the lyotropic liquid crystal and the latex colloidal particles. When the diameter of the doped latex particles is comparable to the microscopic characteristic length of the liquid crystalline order, defects of the liquid crystals are excited around the latex particles. This elastic cotupling between the liquid crystalline order and the doped particles could produce the new type of the long-range attractive interparticle interaction. In other words, this interaction can be transmitted between particles by the microscopic distortion of background liquid crystalline order. It is much characteristic that this interparticle interaction have intrinsically long-range nature because of its elastic origin. For this reason, these types of long-range force are much important to construct and maintain the mezoscopic supramolecular system, such as biological systems, because the short range intermolecular interaction can play no role between quite large molecular assemblies or macromolecules.

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Effects of the surface LC alignment order on electro-optical characteristics of twisted nematic LCDs were studied, experimentally. Surface aligning order was controlled by changing magnetic field strength in MOLCA (Magnetically Oriented Liquid Crystalline Adsorbate) treatment. By deteriorating the order, the area of contrast ratio above 10:1 and without any gray scale inversion shifted vertically downward, compared with conventional rubbing TN-LCD. The transitions in chromaticity diagram with changing of viewing angle at 3 volts rms were greatly suppressed. Moreover, response time in decay was shortened.

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The experimental investigation has been made for the influences of such parameters as the cell thickness d, the factor d/P₀, the pretilt angle, the wave form of applied voltage, and temperature on the bistability in the BTN (bistable twisted nematic) liquid crystal cell with the twisted angle of 180° as the initial state. The occurrence of bistability was confirmed in the range 0.5 < d/P₀ < 0.75. The bisstability was evaluated by using the memory factor. As a result, it was known that the memory factor is independent of the ratio d/P₀, however, it decreases with the increase of cell thickness d. From the observation with art optical microscope, it was confirmed that the degradation of memory is governed by the movement of the disclination separating the 180° twisted state and the 0° or 360° twisted states. As the temperature was raised, the memory factor was abruptly degraded above a certain temperature at which the d/P₀ ratio is taken out the range 0.5 < d/P₀ < 0.75.

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Based on the Stokes parameter method (SPM), we develop a 2D Stokes parameter method for measurements of 2D cell thickness and twist angle distributions in twisted nematic (TN) liquid crystal cells. A 2D SPM system is set up by use of a polarizing microscope, in which the 2D distributions of cell thickness and twist angle of some sample cells are measured. Some preliminary experimental results demonstrate the 2D SPM's validity. Finally, the measurement accuracy of the 2D SPM system is discussed.

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A reflective color STN-LCD with a single polarizer and double retardation films has been investigated. The double retardation films arranged in front of LC-layer enabled the LCD to contain reflective electrodes inside the panel. This configuration achieved the bright image with no parallax. We have realized 7.8-in.-diagonal reflective color STN-LCDs(640 x 480) which have 15% reflectance, 1 : 14 contrast ratio, 4096 color capability and the sufficient color gamut.

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An optimization method of phase plates is proposed for achieving black and white representation in STN-LCDs with single polarizers for applications to reflective color LCDs. Using this method, good black and white representation with the maximum contrast ratio of 5, reflectance of 22% and good achromaticities are achieved for an STN -LCD fabricated.

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We developed novel liquid crystalline polymer film that improved viewing angle characteristics of TN-LCDs. The film parameters were optimized by the computer simulation. The estimation of the computer simulation was coincident with the experimental result. Viewing angle characteristics of TN-LCDs with our films were superior to those of the conventional one especially in vertical direction.

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The electro-optical characteristics of IPS mode TFT-LCDs were studied by using device simulations. Simulation were utilized to obtain design principles for low driving voltage, low crosstalk between pixels and wide viewing angle. We found electrode width and tilt angle of liquid crystal molecules at substrate surface are key points to optimize the electronic- and optical performance.

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Unusual characteristics of the voltage-holding ratio were found when using in-plane switching of homogeneously oriented nematic liquid crystals. Even employing liquid crystals with much lower resistivity than is applicable to the conventional active matrix driving technique, voltage-holding ratio characteristics were higher than those in conventional electric fields applied along the direction perpendicular to the substrate plane. The unusual holding ratio characteristics were attributed to the electric field direction being approximately parallel to the substrate plane.

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The applied voltage dependence of VHR(voltage holding ratio) were measered for N-LC cells. Three types of polyimide were used as alignment material. The nematic mixtures ZLI-2293 and ZLI-4792 and a single compound 5CB were examined as LC material. The voltage dependence of VHR was affected by both LC material and alignment material. Some computer simulation were carried out in order to clarify the mechanism of such phenomenon.

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Inclined homeotropic alignment was realized by irradiation of unpolarized ultraviolet light on a polyimide film that originally exhibited homeotropic alignment. Unpolarized UV light was irradiated from an oblique direction (45-degree inclined angle). The liquid crystal cell with a pair of inclined homeotropic aligned substrates and nematic liquid crystal with negative dielectric anisotropy exhibits a high contrast ratio (over 1000) and a bright transmittance (same as a TN cell, around 35%).

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The charge-discharge characteristics of the thin polymer films used for liquid crystal alignment materials were measured under vacuum with the film thickness of 300nm. The results showed that the internal offset DC voltage of LC cells was related to the charge-discharge characteristics of the alignment films. Also, the internal offset DC voltage of LC cells was discussed based on the equivalent circuit of LC cell, and it was found that the capability of the charges accumulated at the interface of liquid crystal and alignment film could be evaluated by the time constant, i.e. RC of the alignment films.

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We designed and synthesized new photo-alignment materials based on chalcone structure with superior photo-reactivity to cinnamate derivatives. From the observation of photochemical reaction, we found that the new material reacted at longer wavelength. And they also showed higher sensitivity compared with PVCi. Relationship between molecular structure and photo-reactivity was clarified. From the observation of LC alignment, the new material is also characterized by higher sensitivity at longer wavelength compared with PVCi.

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Phase transitional and reorientational behavior of a nematic liquid crystal photo-regulated by azobenzene derivative Langumuir-Blodgett (LB) film or 'Command Surfaces' have been studied by infrared spectroscopy. A thermal isomerization from cis to trans conformations takes place within 15 minutes from the completion of ultraviolet irradiation, while a consequential phase transition from homeotropic to isotropic phases has been found about three quarters of an hour after the irradiation. FT-IR thus is very powerful technique to determine of the phase transition between homeotropic and isotropic as well as the reorientation.

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We investigated the alignment behavior of low-molecular-weight (LMW) liquid crystal (LC) on photoreactive side-chain liquid-crystalline polymer (SLCP) films induced by linearly polarized (LP) UV light. The effect of the LP-photoreaction conditions and the spacer length between the biphenyl and cinnamoyl groups were examined. The alignment direction of LMW-LC was parallel to the electric vector of the incident LP-UV light in the beginning of the photoreaction and changed to perpendicular when the most of the cirmamoyl group had reacted. These are the consequence of the difference of the interaction between LMW-LC and the biphenyl group or the photoreacted cinnamoyl group.

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Homogenous and TN cells are made by using photoalignment technique after the liquid crystal is injected between non alignment PVCi coated substrates. We find that the LC director does not change when the linearly polarized UV light is irradiated to the LC cell in the nematic phase. However, homogenous orientation can be obtained when the linearly polarized UV light is irradiated in the isotropic phase.

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Measurement techniques of an azimuthal anchoring energy are discussed in LC cells in which LC molecules align homogeneously on one substrate and axial-symmetrically on another substrate. These LC cells provide arbitrary combination angles of easy axes from 0° to 90°. Anchoring energies can be estimated semi-quantitatively with ease, but a high accuracy measurement is also possible. Moreover, the anchoring energy of a flow-induced alignment is tried to measure.

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Liquid crystal alignment and memory properties on a polymer surface after applying and removing the voltage are studied. Two dimensional Stokes parameters of the memorized region are obtained and twist angle distributions are measured by using the Stokes parameter method (SPM). The result implies that the twist angle of LC molecules in the memory region decreases continuously as increasing the distance from the electrode edge. The maximum twist angle was smaller than 90°.

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In order to determine cell thickness and twist angle of TNLC cells accurately, a new Stokes parameter method named improved Stokes parameter method (ISPM) is presented, which is independent on the LC molecular alignment directions at the front substrate of the cell. The function equations of the Stokes parameters with cell thickness and twist angle are deduced, and the experiment method are introduced. The preliminary experimental results verify its validity. Finally, the measurement accuracy of this ISPM is discussed.

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We have prepared supramolecular liquid crystalline polyamides. These polyamides consist of 2,6-bis(amino)pyridyl group in their main chains, which formed molecular complexes with benzoie acids through double hydrogen bonds. They also formed liquid crystalline complexes with carboxyl-terminated azobenzene derivatives. The copolymeric complexes of a polyamide and two benzoic acid derivatives showed liquid-crystalline phases with wider temperature range.

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The liquid crystalline ion complexes consisting of amino-containing polymers and alkanoic acids were prepared and their thermal and mesomorphie properties were examined. The liquid crystalline ion complexes [DD/Cm: m=the carbon number of Cm] of poly(amide amine) dendrimer [DD] and n-alkanoic acid [Cm] showed a thermotropic smectic fluid phase with fan and oily streak textures. The liquid crystalline ion complexes derived from polyallylamine formed a smectic phase with fan and homeotropic textures.

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Liquid crystalline monomers(LCM) and difunctional monomers were synthesized. Polymer networks were obtained by polymerization of mixtures of LCM and difunctional monomers. It was found that a stability of the molecular orientation and a transparency of the polymer networks strongly depended on the structure and concentration of difunctional monomers. Consequently, highly transparent polymer networks were obtained by polymerizing LCM with difunctional monomers showing liquid crystallinity. In addition, polymerization of a mixture of LCMs and azobenzene compound was investigated relating to an effect of photoisomerization on properties of polymer networks.

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To explore the effect of molecular packing in a liquid-crystalline phase, chiral liquid-crystalline methacrylate monomers with polymerizable group attached to the rigid core through a short methylene spacer (carbon number of 2) and a long methylene spacer (carbon number of 11) were synthesized. The monomers were found to exhibit chiral smectic C and smectic A phases by optical polarizing microscopy and DSC. The monomers were photopolymerized which 1-hydroxycyclohexyl phenyl ketone as a photoinitiator at various temperatures. The polymerization was carried out in a cell which was composed of two glass substrates with ITO electrodes. It w as found that reactivity of the monomer having a short spacer is higher than that of the monomer having a long spacer, Furthermore, the stored image obtained by photopolymerization in SmC^* phase has been stable for three months.

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In this work, we have investigated phase transitions and molecular motions of poly [ethylene 1,2-bis (phenoxy) ethane-4,4'-dicarboxylate] (PEG/EG) and poly [ethylene 1,2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate] (Cl-PEC/EG). In both PEG/EG and Cl-PEC/EG, any mesophase was not observed. Refering to our previous results on other polyesters having PEC, it was deduced that an introduction of rigid phenyl groups to PEC instead of flexible EG needs an appearance of mesophase in PEC-polyesters. It is found that the substitution of Cl to the phenyl group in PEC make the backbone chains of PEC-polyester more rigid.

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Two liquid crystalline (LC) epoxy resins were synthesized by curing LC diepoxide with LC hardening compound, diglycidyloxy azoxybenzene (DGA) with 4,4'-bis(ω -carboxy decanoxy) azoxybenzene (CAA10) and DGA with 4,4'-bis(ω-hydroxy undecanoxy)azoxybenzene (HAA11), and their reaction mechanism, mesomorphic phase transition and thermal exparasion were investigated. The fully gelated DGA-CAA10 formed a network structure in which one interchain crosslink was made per 5,6 repeating unit, and showed no mesophase. The DGA-HAA11 of linear typed polymer showed a smectic A phase when not fully cured but nematic phase with curing. Thermaal expansion coefficient (α)was about 2.2 × 10^-4 ℃^-1 below Tg and 3.4 × 10^-4 ℃^-1 above Tg for the fully gelated DGA-CAA10 and about 2.3 × 10^-4 ℃^-1 below Tg and about 6.5 × 10^-4 ℃^-1 above Tg for the fully cured DGA-HAA11.

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Temperature dependence of the viscosity for a neat sample of a side-chain-type liquid crystalline polysiloxane (LCS) was measured from the isotropic phase to the liquid crystalline phase. At temperatures much higher than the isotropic - liquid crystalline phase transition temperature (Tc) measured by a polarized optical microscope, the viscosity was almost independent of the shear rate, and it increased as the temperature decreased. At temperatures slightly higher than Tc the viscosity measured at shear rates of 3Os^-1 and 5Os^-1 decreased steeply as the temperature decreased. These results were discussed in terms of the shear-induced ordering of mesogens of the LCS even at the temperatures above Tc.

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A (liquid crystal/polymer) composite film has been prepared by an in-situ phactopolymerization of a mixture composed of an UV curable liquid crystal and a liquid crystal. The temperature dependence of retardation of the film is reversible. The effects of the clearing point and the concentration of a liquid crystal on the dependence are discussed.

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We investigated the influence of the molecular interaction at the surface between liquid crystal and polymer to the electro-optical characteristics of polymer-dispersed LCD by experiments and computer simulations. It was found that driving voltage of LCD are affected by the affinity between the liquid crystal and monofunctional monomers, and molecular structure of monofunctional monomers.

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We have investigated the migration of SiO₂ particles by applying AC electric field. The trace of their movement reflected the smectic layer alignment. In the isotropic and N^* phases, which have no layer structure, the particles moved on a circle. On the contrary, in the smectic A and C^* phases, they moved along the smectic layer.

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Freely Suspended (FS) ferroelectric liquid crystal films have been fabricated successfully. Electro-optic measurements of FS films have been carried out. The optical response depends on the magnitude of the applied electricfield. The response to polarization reversal at intermediate field shows anomaly, in which piled 2π-walls are observed. The electro-optic response in the film has been analyzed on the basis of a switching model with a distribution function for the molecular orientation.

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Anomalous layer alignment has been observed in the ferroelectric liquid crystal having a direct phase transition from chiral nematic to smectic C. With decreasing temperature from nematic to smectic C phases, two kinds of domains grow along the rubbing direction, in which smectic layers align in the different directions. We can successfully control the alignment of the smectic layers by means of the application of the electric field at the phase transition and realize a fine grating.

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Antiferroelecttic-like tristable switching was observed in smectic liquid crystal mixtures containing chiral dopants derived from trifluoromethylated pyranose. Result of selective reflection measurement shows that the phase showing the tristable switching is not antiferroelectric but ferroelectuic. Mechanisms for tristable switching are proposed on the basis of the ultrashort pitch. Conoscopic observation was made to see the bulk state free from surfaces.

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In the polarization dependency of infrared (IR) and polarization dependency of time-resolved IR measurements for FLC mixture containing 20% chiral dopant, we could observe that the apparent tilt angle and dichroic ratio in the dynamic state are larger than those in the static state. These results suggest that the order of the orientation is higher in the dynamic state than in the static state. In order to confirm the high orientation order in the dynamic state, we performed time-resolved IR measurements for the FLC mixture with the delay time being longer than the response time. The relaxation process was clearly observed after the response time.

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The generalized mean-filed theory by Dumorngrattana and Huang, in which higher order terms are introduced into the free energy expression, succeeded to explain the anomalous change in Ps/ θ of DOBAMBC at the A-C^* phase transition. Generally speaking, it should be around the tri-critical point that the higher order terms are important. In the present study, the temperature dependence of Ps/ θ of several ferroelectric liquid crystals was investigated in detail.

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Improvement of the efficiency of NLO properties of liquid crystalline main-chain polymers has been studied. The sample polymers are copolymers of 2-hydroxy-6-naphtonic acid (HNA) with 4-hydroxy-benzoic acid (PHB). SHGs for the samples processed by mechanical stretching and for electrically poled samples were compared. Electrical treatments have been done using sandwitch type cell, transversely applied cell, and Corona poling method at the liquid crystalline temperature.

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Banana-shaped molecules have been synthesized and their electro-optical properties were investigated. The molecules are non-chiral, but the liquid crystals show ferroelectric and circular dichroism. Ferroelectricity could be detected in the SmAb and the SmHb phases. On the basis of the texture observation and the circular dichroism of scattered light, we elucidated the existence of helices in the SmAb and the Smblue phases.

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We have studied the nonlinear electrooptical relaxation spectra of the Goldstone mode in a ferroelectric liquid crystal (FLC). The experimentally obtained linear spectrum shows a single relaxation of Debye type and the nonlinear spectra of second and third orders exhibit an extended form of Debye type to the nonlinear case. We have also studied the electrooptical response theoretically by means of a simple torque balance equation describing the dynamics of the Goldstone mode. It is found that the linear and nonlinear spectra calculated are in good agreement with the experimentally obtained ones.

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A series of 2-(4-n-alkoxybiphenl)-5-(4-methylphenyl)pyridne (CH₃C₆H₄C₅H₅NC₆H₄C₆H₄OC_nH_2n+1, n=1-10) (ABPMPP) was synthesized and their mesogenicity was studied using polarizing microscope observations and DSC measurements. The polymorphism of smectic phases was observed in the ABPMPP homologues of n≧3, while a nematic phase was found in all the member of ABPMPP.

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The phase transition behavior of monosubstituted ferrocene derivatives containing cholesteryl group as a mesogenic one, [4-[ω -(cholesteryloxycarbonyl)alkoxycarbonyl]phenyl]ferrocene (abbreviated hereafter to CAPF-n, where n is the carbon number of the flexible methylene chain), have been investigated using various methods in our laboratory. In the present study, the dynamic viscoelastic measurements for CAPF-6 were carried out as a function of frequency and temperature in the smectic C and the liquid phases. In the smectic C phase, the storage modulus(G') curves can not be superposed on to a single master curve. That is, G' curves in a lower frequency range at higher temperature deviate on the master curve, in contrast to those in a higher frequency range at lower temperature which are well superposed on to the single master curve. This fact suggests that the smectic structure changes gradually into less order at higer temperature in the smectic phase.

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A series of monosubstituted ferrocene derivatives, [4-[ω-[4'-(4"-methoxyphenoxycarbonyl)phenoxycarbonyl]alkoxycarbonyl]phenyl]ferrocene (abbreviated hereafter MPAF-n. where n is a number of carbon atoms in methylene unit) were synthesized and studied on the liquid crystallinity of the compound in our laboratory. Only 4 kinds of MPAF-n showed the liquid crystallinity, where n=4, 6, 10 and 11, whereas 9 kinds of MPAF-n were synthesized. In this study, molecular and crystal structure of some of MPAF-n were determined by X-ray diffraction method. We will discuss the structure of liquid crystalline phase on the base of crystal structure.

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Two kinds of monosubstituted ferrocene derivatives with the same mesogen have been prepared. One is containing a disiloxane unit in the spacer, and another is having alkyl spacer. Thermal properties of these compounds have been studied by differential scanning calorimeter (DSC) and polarizing microscope. Furthermore, these compounds were compared from view points of the behavior of phase transitions. The derivative having siloxane spacer has exhibited no liquid crystalline phase, and only crystal - isotropic liquid transition has been observed. On the other hand, the derivative having alkyl spacer has shown a nematic phase. The introduction of the disiloxane unit in the spacer resulted in a drop of transition temperature.

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