We succeeded in the formation of nematic liquid-crystalline physical gels by the hydrogen-bonded network formation of amino acid derivatives in nematic liquid crystals. The resultant liquid-crystalline gels exhibit microphase-separated structures and electro-optic responses in twisted nematic (TN) cells. Acceleration of response behavior of nematic liquid crystals by the physical gel formation has been observed. Response behavior of a fluorinated nematic liquid crystal can be improved by the use of the network aggregates.

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This paper describes the mesomorphic properties of 4-(4-alkoxyphenoxycarbonyl)phenyl 3-alkoxy-4-bromobenzoates, and the molecular arrangement in smectic phases has been discussed in terms of their molecular structure calculated by AM1 method.

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We investigated the (polymer / liquid crystal) composite films using nematic liquid crystal E7 and UV curable acrylate monomer in oder to achieve a low driving voltage and a high contrast. This report presents the light switching characteristics of fluoro benzoyl acrylate/E7 composite films. The composite film using 3,5-Difluoro benzoyl acrylate as a monomer would be driven at 19Vrms and exhibited the contrast of 58.

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Behaviors and organization of liquid crystalline compounds, N, N-bis{4-[4-(4-alkoxybenzoyloxy) benzoyloxylbenzoyl}alkylamine (1), which have an iminodicarbonyl moiety as the central junction and consist of two mesogenic units in twisted parallel, were investigated by polarized light optical microscopy, differential scanning calorimetry and single crystal- and powder X-ray diffraction. Compound 1a showed nematic phase wilh highly oriented textures, and Id showed smectic A phase in which overlapping of alkyl chains between the layers was observed. The overlapping of alkyl chains originates in the structure of the molecules which have two cores with three alkyl chains in parallel.

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[Polymer/liquid crystal (LC)] composite films are practically applied for switchable windows. In this study, mesomorphic characteristics, aggregation states and electro-optical switching effects of the composite systems composed of a polymer network formed by discotic liquid crystalline monomer and low molecular weight nematic liquid crystals (LCs) have been investigated. An anisotropic polymer network was formed in the antiparallel rubbing cell by photopolymerizing the discotic LC monomer in mesophases. The new composite system showed the light-switching behavior with a high contrast. The rise response time of the composite system was 0.68 ms at an applied voltage of 20 Vrms at 298 K. On the other hand, the decay response time of the composite was 17.2 ms at 298 K.

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Two mesogens were connected with O=C-N(R)-C-O to give a twisted arrangement of the mesogens because of the electrostatic repulsion between the two carbonyl-oxygen atoms. In this structure, the excluded volume effect must become the minimum to give the liquid crystallinity. (RO-C6H4-COO-C6H4-CC-C6H4-CO)2NR' and (RO-C6H4'COO-C6H4-C2C2-C6H4-CO)2NR' (R=n-alkyl) were synthesized and those liquid crystal phases were obtained. We report the molecular structures and the properties.

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A smectic A polymer network having permanently, macroscopically uniformly aligned director and smectic layers is synthesized, which is completely optically transparent. By applying mechanical fields in the direction parallel to the layer normal the S_A-elastomer becomes opaque if the strain is beyond 3%. Moreover the modulus of the elastomer, that is large under small strain, changes to a small modulus above the strain of 3%. Obviously at this point the monodomain structure is broken down to change a polydomain structure. Strain depending X-ray measurements reveal that the broken layers are rotated by the mechanical field and regions exist having nematic like order between broken layers.

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We studied photopolymerizable 3-ring phenylacetylene diacryrate monomers and polymers. The monomers exhibited nematic phase and high Δn around 0.35. The homogeneous alignment polymes were obtained by UV iradiation of these monomers. Δn of polymers were affected by polymerization temperatures. Wide nematic range monomers are useful for obtaining of higher Δn polymers.

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We prepared the (polymer/liquid crystal) composite films using nematic LC and UV curable LC with aligning treatment, which exhibited the characteristics of the reverse mode. In this study, we investigated the light switching characteristics of the composite films consisting of 4'-cyanophenyl 4-acryloyloxy benzoate (ACPBCN) as a monomer and E7. The composite film would be driven at less 20 Vrms, and the hysteresis was improved by the addition of diacrylate monomer (PBAHB).

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The synthesis and properties of chiral 2-phenylpropionic acid derivatives were studied in the purpose of application as chiral additive for various liquid crystal devices. These compounds showed lower viscosity and larger helical twisting power compared with available chiral compounds. The relationship between structure and properties of these compounds were discussed.

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Thermal phase transition behavior of cyclobutadienecobalt derivatives having long alkoxy lateral groups which we prepared recently was re-investigated in detail by the optical measurement using the crossed polarizers and different scanning calorimetry (DSC). These cyclobutadienecobalt derivatives were found to reveal the solid polymorphism: two types of crystals K_1 and K_2 (crystals with lower and higher m.p., respectively) were observed. The melting points of both K_1 and K_2 became lower as the number of the carbon atoms in the alkoxy chain increased.

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A new compounds, 4-[ω-(cholesteryloxycarbonyl)alkoxycarbonyl]biphenyl(CABP-n, where n is the carbon number of the flexible chain), were synthesized and their dynamic viscoelastic properties were measured. The results obtained here were discussed with those of [4-[ω-(cholesteryloxycarbonyl)alkoxycarbonyl]phenyll ferrocene(CAPF-n, where n is the carboll number of the flexible chain) from point of view of a steric effect of ferrocenyl group. The storage modulus of elasticity (G') of CAPF・9 was changed continuously around the clearing temperature, while an abrupt change of G' was observed at clearing temperature in CABP-9. It is considered that the continuous changing of G' in CAPF-n at around Tcl is attributed to be a steric effect of ferrocenyl group.

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In the crystal structure of the title compound, the molecules lie parallel to the longest axis and form layers similar to those of the smectic A structure of liquid crystals. In the molecular structure, one of the terminal hydroxyl groups has a gauche conformation with respect to the hydrocarbon skeleton, while the other is trans. These features are similar to those of the homologues with an odd number of carbon atoms, but different from those with an even number.

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Novel liquid crystalline compounds, 3,4,5-trialkoxybenzoic acid anhydrides 1 were synthesized and the properties were investigated. The half-disk molecule 1 has two carbonyl groups which are in syn-parallel. In the process of organization of the columnar phase, to cancel the large dipole, a dimer generates from two molecules with anti-parallel manner, and the dimers are assembled into a column. Two types of dimerizations, uneven-parallelly (A) and perpendicularly (B) dimerized, are anticipated for the anti-parallel association. From powder X-ray diffraction, the diameters observed are shorter than those calculated in molecular modeling using MM2. In polarized-light microscopy, the textures indicated that the molecules are not tilt in the column. Accordingly, dimer B seems to be the reasonable model to explain the short lengths because the each molecule is tilt and the average director are parallel to the column.

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The series of monosubstituted ferrocene derivatives, [4-[ω-[4-(4-methoxyphenoxycarbonyl)phenoxy-carbonyl]alkoxycarbonyl]phenyl]ferrocene (abbreviated hereafter MPAF-n, where n is the carbon number of the methylene chain) have been prepared and studied on the liquid crystallinity of the compound in our laboratory. Only 6 kinds of MPAF-n showed the liquid crystallinity, where n=4, 6, 8, 9, 10 and 11, whereas ll kinds of MPAF-n were synthesized. In this study, molecular and crystal structure of MPAF-1 was determined by X-ray diffraction method in order to discuss the structure of liquid crystalline MPAF-n.

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The photoconductive properties of 5,10,15,20-tetrakis(4-n-pentadecylphenyl)porphinato-oxovanadium(IV) was investigated to be compared with those of the free base compound for a symmetrical sandwich-type ITO cell. The similar photocurrent rectification behavior to the free base tetraphenylporphyrin mesogen was shown. However, the observed photocurrents were remarkably larger than that of the free base compound for all phases. The temperature dependence of the dark- and photo-currents were also investigated.

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The two homologous series of monosubstituted (ω-[4-(4'-hexyloxycalbonylbiphenyl)oxylalkyl ferrocene; HBAF-n, n is the number of carbon atoms in the metylene chain) and disubstituted ferrocene derivatives (1,1'-bis[ω-[4-(4'-hexyloxycalbonylbiphenyl)oxylalkyl]ferrocene; bHBAF-n), which are shown in Figure 1, have been prepared. The phase transition phenomena of these compounds have been studied using the DSC and the polarizing microscope. All of HBAF-n exhibited no liquid crystal phase, while four of seven bHBAF-n showed the liquid crystal phase. These liquid crystal phases were identified to be a smectic C phase.

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Disubstituted ferrocenyl compounds having two benzylideneaniline mesogens, 1 and 2, and that having a benzylideneaniline and a biphenyl mesogens 3, showed isotropic liquid to liquid crystalline phase transition even though they partially formed charge transfer complexes with tetracyanoethylene (TCNE). The phase transitioin temperatures decreased with increasing concentration of TCNE, and no liquid crystalline phase was observed when the TCNE concentration was higher than 32, 40, and 19 mol% for 1, 2, and 3, respectively. The disappearance of liquid crystalline phase at; high TCNE concentrations can be ascribed to attenuation of the liquid crystal forming tendency of the mesogenic group by bulky ferrocene/TCNE complex.

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The [liquid crystalline polymer network (LCPN) / low molecular weight liquid crystal (LMWLC) / chiral dopant] composite systems were prepared by photo-polymerizing the (photo-polymerizablc liquid crystalline monomer / LMWLC / chiral dopant) mixtures in the homogencously oriented smectic-A (SA) phase. The composite exhibited a drastic reversible change in optical properties between transparent statc and selective reflection one at the SA-chural nematic (N) phase transition. By controlling the fraction of the LCPN and chiral dopant in the composite, file wavelength of reflection band could be cxtended up to the infrared (IR) region. Such a thermo-responsive IR reflection is applicable as a thenno-scnsitive IR shutter.

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New troponoid liquid crystals (1, 2) with a 5-aminotropolone skeleton were prepared. Dicatenar molecules having two aliphatic chains (1) showed smectic C phases, but they were decomposed around 220℃. From the X-ray diffraction studies, the layer spacing was determined 0.8 times shorter than the calculated molecular length, suggesting that the molecular long axes to be tilted to the layer plane. On the other hand, tetracatenar molecules (2) showed mesophases when alkoxyl chains were long.

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Amphiphilic liquid crystal materials with a mesogenic terminal unit were synthesized. Their thermal and orientational behavior were examined. Moreover, their lyotropic properties were estimated. A low-molecular-weight amphiphilic liquid crystal (ALC) showed no thermotropic mesophases. However, a lyotropic system obtained from ALC formed columnar and lamellar mesophases. The X-ray diffraction measurements and the polarizing microscope observation supported the formation of the columnar and lamellar mesophases. A polymethacrylate with ALC unit in the side-chain exhibited thermotropic smecctic A and C phases in the range from glass transition to isotropization points.

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We developed new ion conductive liquid-crystalline materials using of oligo(ethylene oxide) moieties. We focused on negative dielectric anisotropy and smectic liquid crystallinity in relatively low temperature range of lateral fluorine(s)-substituted liquid crystals. In the present study, we synthesized fluorine-substituted mesogenic twin molecules containing an oxyethylene moiety. The complexation of the compound with lithium triflate induced an improved thermal stability of the smectic phase. The degree of the positive deviation by the complexation was up to 100℃. The stabilization was not observed for the complexes of a homologous compound without the fluorine substituent. 1^<19>F NMR spectra suggested that the significant stabilization was attributed to interaction between the fluorine and lithium cation. When the mesogenic core of the complex formed a homeotropically aligned monodomain, the ionic conductivity along the layer of the oxyethylene moiety became higher than that for the unaligned one. This result suggests that long range conductive paths have been formed in the complex.

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Amphiphilic materials (AMs) with a polyiminocthylene unit were synthesized. Their thermotropic and lyotropic liquid crystalline behavior was examined. Also, novel branched polymers(BPAMs) with AM units were prepared. AMs and BPAMs were easily miscible with water. The lyotropic systems consisting of AMs and water formed lyomcsophascs. The lyotropic systems of BPAMs and water also exhibited a smectic A lyomesophasc.

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New troponoid liquid crystals with a bitropolone skelton were prepared. The ester derivatives (1) had enantiotropic smectic A and/or C phases with higher thermal stabilities than the corresponding benzenoid. However the ether derivatives (2) were not mesomorphic. From the X-ray diffraction studies of 2, the layer spacings were estimated to be 35.6 Å for smectic A and 36.5 Å for smectic C, respectively. The layer spacings are shoter than the calculated molecular length (43.6 Å) for a bitropolone derivative. This indicated that the molecular long axes ate tilted to the layer plane.

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New chiral dopants for nematic liquid crystals were synthesized using optically active 2-phenylpropanoic acid derivatives, and phenylcyclohexane cores. Chiral nematic liquid crystal mixtures were prepared by adding 1 wt% of chiral dopant into an achiral host liquid crystal mixture (ZLI-1132). The helical piches of the chiral nematic phase were measured using Cano-wedge cell. The magnitude of helical twisting power (HTP) was largely influenced by the structure of the 2-phenylpropanoic acid frames, the phenylcyclohexane cores, and the linkages between the asymmetric frame and the core moiety. The relationship between the HTP and the chiral dopant structures was studied.

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N-[4-(4-n-alkoxybenzoyloxy)-2-hydroxy-benzylidene]-methylanilines[nAHmM(n; n=l-8, m; m=2: -ortho, m=3: -meta, m=4: -para)] were newly synthesized. They exhibited a nematic phase except for 1AH3M. The temperature dependence of Raman spectra of nAHmM has been observed in the spectral range of 800-1800cm^<-1>. In a group of nAHmM, the Raman band at about 1365cm^<-1> decreased in intensity and wavenumber through the solid-nematic phase transition. In the other group, the corresponding band increased through the phase transition. The band has been assigned to the φ-N stretching vibration. Such a behavior can be explained by the molecular conformations with different twist angles of the aniline ring to the salicylaldimino part of the molecule. Some of nAHmM showed a photochromic property in the solid state.

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We have found that the condensation-type aromatic polymers such as polyamide, polyurea and polyester acted as LC photo-alignment layers by the exposure of the linearly polarized UV light. These LC photo-alignment materials showed very high sensitivity and the obtained TN cell with them achieved the durability against light and heat. However, the photo-reactivity and the photo-induced alignment mechanism have not yet been revealed. In this study, two kinds of aromatic polyesters with and without the ability of photo-alignment material were prepared, and their different photo-reactivities were investigated by means of UV-Vis absorption spectra, surface energy and IRRAS. As a result, the photo-reaction induced by n-π exciting of carbonyl group anisotropically occmted with no relation to the performance as the LC alignment layer. But it was suggested that the reaction selectivity was different between the two kinds of the polyesters.

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We designed and synthesized fluorine-substituted liquid crystals containing oligo(ethylene oxide) end groups for the development of novel anisotropic ion conductive materials. We mixed these compounds with lithium triflate and examined the phase transition behavior of the resulting complexes. The smectic-isotropic transition temperatures were increased by the addition of lithium triflate. Comparison of the phase transition behavior with the corresponding non-fluorinated compound revealed that the stabilization of the smectic phase of the fiuorinated complexes was more significant than those of the corresponding non-fluorinated complexes. ^<19>F and ^7Li NMR spectra suggested that the stabilization in a wide range of temperatures should be induced by a specific molecular interaction between the fluorine substituent and the lithium ions.

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We describe the synthesis of a new photoreactive polymer liquid crystal (PLC) and the photoalignment control of liquid crystal on PLC films by linearly polarized (LP) UV light irradiation. The irradiated PLC film showed negative dichroism and the homogeneous LC alignment can be achieved on the irradiated PLC film. The alignment direction was perpendicular to the E of the LP-UV light, and was changed parallel to E when the irradiation time was long.

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Trans-difluorostilbene (DFS) compounds were reported to be superior liquid crystal materials with low viscosity and high Δn for STN-LCDs with fast response time. We have attempted to introduce of fluorinated polar terminal groups to the DFS compounds for obtaining higher Δε values. The mixtures for TFT-LCDs with fast response time were developed using these new compounds.

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Photo-cross-linkable polymethacrylate comprising a coumarinmethylbiphenyl side group was synthesized. A linearly polarized ultraviolet (LP-UV) light irradiated the synthesized polymer films, and the resultant films were applied to the alignment layer for liquid crystals (LCs). The optical anisotropy was induced by LP-UV light irradiation and the positive dichroism was generated when the film was exposed near clearing temperature of the film. The LC could be aligned on the exposed films and the alignment direction was controlled by adjusting the irradiation condition. The photo-cross-linked mesogenic side groups determine the LC alignment direction.

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New chiral dopants having a Irifluoromethvl group at the terminal position were synthesized using oplically active 2-phenylpropanoic acid or 4,4,4-trifluoro-3-phenylbulanoic acid. Chiral nematic liquid crystal mixtures were prepared by adding one weight percent of a clriral dopant into an achiral host liquid crystal. The helical pitches of the chiral nematic phases were measured using Cane-wedge cell. Some chiral dopants showed quilt large values of helical twisling power (HTP). Chiral dopanls having trifluoromethyl group at lhe terminal position showed relatively small HTP values. On the other hand, HTP values depended on the linkage between a core and a chiral moiety. The relationship between the molecular structures and the magnitude of HTP was discussed.

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We investigated the effect of the substituent of the mesogenic side group of the copolymer liquid crystal films on the photoinduced alignment behavior. The optical anisotropy of the polymer films was induced by the linearly polarized (LP) UV photoreaction followed by annealing around the clearing temperature. We clarified that the polymer should exhibit liquid crystallinity to achieve the thermal orientation of the mesogenic side groups.

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A ferulic acid derivative which has a long ethyleneoxide group was obtained via esterification reaction from a oxyethylene-substituted ferulic acid and 4-cyano-4'-hydroxybiphenyl. The compound was identified with an adduct of esterificated ferulic acid derivative and N, N'-dicyclohexylcarbodiimide (DCC) used in the esterification reaction by the NMR. This compound showed a nematic phase and some other phases as well on cooling under the polarized microscopy experiments. The phase transition behaviour was complicated induced by thermal dissociation of the adduct. A single crystal was obtained by recrystallization from acetone to investigate the structure of the adduct.

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Troponoid twins 1 and 2 which have long alkyl chains show a smectic C phase. By X-ray diffraction study, the layer spacing of I is shorter than the molecular length of I calculated by MM2 method. We plotted the layer spacing vs the terminal alkyl chain length (m) to estimate that the layer spacing of the core part is 12.6 Å. From these results, we proposed the layer structures of twin dimers 1.

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We studied the feasibility of ultra-low-frequency driving of twisted nematic liquid crystal displays. Transmittance variation, voltage holding ratio and image sticking were evaluated. The transmittance variation can be explained by the Maxwell-Wagner theory for multi-layered dielectrics. By optimizing alignment films, the obtained variation was only 0.2%. The voltage holding ratio of 99.0% for the frame frequency at 16.7mHz was achieved by using ultra-pure liquid crystal mixture.

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We propose a method to determine twist angle and gap of LC cell by observing dependence of polarization of transmitted light on orientation of LC cell. We found that glass substrates of LC cell influence determined values of twist angle and cell gap, and that 4x4 matrix approximation is needed for precise estimation of twist angle and cell gap.

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For improving the transmitted light efficiency through a LCD panel, we have theoretically and experimentally studied amorphous and mulit-domain vertically-aligned (VA-) LCDs using two circular polarizers, which combined a linear polarizer with a λ/4 retardation film. From the texture observations, dark regions in the panels were almost perfectly ehnunated by using circular polarizers. And the transmitted light efficiency of a multi-domain VA-LCD panel was improved up to 1.6 times that of a conventional panel configuration, so that the steepness of the electric-optical characteristics was also improved.

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We have developed a fast response 39 cm (15.2 inch) -diagonal wide OCB mode TFT-LCD with enhanced viewing angle characteristics. The prototype OCB panel showed a fast response o1 less than 6 ms, even between any brightness level of 5 gray scale levels. Also the wide viewing angle characteristics of 160 degrees horizontally and 120 degrees vertically have been obtained. And it has been proved that OCB mode TFT-LCDs were suitable for audio-visual applications such as LCD televisions.

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The near-infrared interference method (NIR-IM) enables the cell gap of reflective color-LCDs to be determined non-destructively and, therefore, this method can be used in the manufacture process. Since the reflective color-LCD has a multi-layer structure, the spectrum obtained by the NIR-IM contains a complex oscillating interference pattern. In the present study, the multi-layer analysis was applied to a cell gap measurement of a reflective color-LCD. The interference spectrum was reproduced theoretically using multi-layer information together with the refractive index and thickness of each layer.

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We investigated the TFT drive of ferroelectric liquid crystals (FLCS). Research on particular polarization switching properties provided us with the technology for quick switching FLCs by using amorphous silicon TFTs. In addition, we clarified size of Ps suitable for the TFT drive of FLCS. We developed the FLC material which was able to be driven by general driver IC.

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A novel measurement method has been developed to optically measure ion density in TFT-LCD panels. We investigated the optical response of twisted-nematic (TN) cells when ions were transported by applying an alternating electric field. A characteristic flickering of transmitted light was observed when a rectangular voltage with a low frequency of 1 Hz was applied to the cells. A peak in light intensity was observed during voltage application. Its height was found to be related to ion density in a linear way. This density was measured by using the transient current technique. We conclude that ion density can be determined by measuring optical response.

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Spontaneous polarization of the ferroelectric liquid crystals induce voltage drop during the holding period in TFT driving and in order to compensate the voltage drop, larger storage capacitance is needed. But that will reduce the aperture ratio and transmittance of the LCD panel. Larger spontaneous polarization induces larger voltage drop, but in that case, the driving voltage is small, so it is possible to do not change the storage capacitance if optimize the spontaneous polarization, driving voltage and the voltage drop.

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A polarizerless reflective guest-host (GH) LCD, which exhibits high luminance and good legibility, has been fabricated by using NLC with a negative Δε that is doped with nanomaterial molecules, fulleren C₆₀, and dichroic dye molecules, where the NLCs are homeotroptically aligned without rubbing. It is considered that the doped C₆₀ molecules may play a role in reducing the order parameter of the host NLC, and in turn, the contrast ratio is enhanced because the transmittance of the field induced black state in our GH-LCD is lower than that in conventional GH-LCD without C₆₀.

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reflective LCD's inner diffusing reflectors have convex and concave surfaces which are designed to scatter lights for viewing directions, and LCD's brightness for viewers depends on the illuminative environment conditions and the reflectors scattering characteristics. So the brightness is difficult to be estimated by simple measurements. For the purpose of analyzing the reflective LCD's brightness in practical conditions, the authors introduced the ambient light distributions of typical use scenes such as an office or a living room into evaluating the LCD From this results, it will be possible to simulate the brightness of LCD in practical conditions.

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"Digital Paper" was recently proposed as a new medium that offers the advantages of both softcopy and hardcopy. This study examines the possibility of surface electric charge driving a liquid crystal medium using an ion projection head for realizing Digital Paper. A guest-host type polymer dispersed liquid crystal sheet medium was prepared. The optical density of the sheet is almost linear to the surface potential from 160 v to 320 v. The surface electric potential necessary for saturated image formation lies in the range 310 v to 350 v for the media used in this experiment.

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sDichroic phosphors are dissolved in p-type and n-type nematic LCs. Solubilily and the tluorescem spectra are measured. The fluorescent color of NK3590 changes from red io yellow due to dissolving in the different LC host. Anisotropic absorption and emission properties of blue green and red dichroic phosphors are investigated. Almost the same chchrote rations in the n-type Lc host are obtained compared to those in the p-type LC host.

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We develop a new Stokes Parameter Method for determining a pretilt angle by measuring Stokes parameters of twisted nematic (TN) liquid crystal cell (LC) at two wavelengths. In addition, a cell thickness and twist angle of the TNLC cell can also be measured simultaneously. First we discuss a validity of this new SPM as compared with a previous SPM by a theoretical calculation. Second the experimental results for the TNLC cell which is fabricated with two different rubbed alignment layers are given, and the results verify its validity.

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We have developed a novel electronic paper consisted of cholesteric liquid crystal(ChLC) and organic photo conductor(OPC). The microencapsulated ChLC stacked on the dual CGL OPC can be switched between focal-conic state and planar stale by light modulation under AC voltage. The prototype demonstrated a bistable and flexible mono-color image. We also showed a feasibility of full-color with a new driving scheme for stacked RGB ChLCs.

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In-plane alignment of liquid crystal molecule, 4-n-octyl-4'-cyanobiphenyl (8CB), on a hydoroxypropyl cellulose was investigated from a microscope observation and an optical instrument measurement. Clear bright patterns were always observed with crossed polarizers The director directions of outgoing side of a nematic cell were determined from the combination of the polarization of incident and scattered light which was obtained by detecting the maximum transmitted intensity.

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