Bent-core liquid crystals exhibit characteristic smectic phases, B1~B8. The B1 phase has a two dimensional modulated structure, and two types models are proposed; a molecular bending plane is parallel (B1) or normal (B1rev) to the modulated plane. In this paper, we will report X-ray results of the B1 phase in a proto-type bent-core liquid crystal, P-6-OPIMB. Based on the results obtained from the uniform B1 domain before and during the applying field using x-ray microbeam diffraction, we concluded that the B1 phase of P-6-OPIMB is B1rev. The molecular orientational order in the B1 phase will be also discussed.

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We investigated photoinduced bending behavior of crosslinked azobenzene liquid-crystalline polymer films with various contents of azobenzene. It was found that the bending speed of the films could be controlled by changing azobenzene contents. In addition, contraction force on photoinduced bending behavior was measured by the thermomechanical analysis. It was observed that the contraction force generated during bending process was dependent on the azobenzene contents of the films.

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Copolymer was obtained by radical polymerization of an azobenzene liquid-crystalline monomer and a monomer having a carboxylic acid. Hydrogen-bonded films were prepared from mixtures of the copolymer and bisazopyridine. The thermal properties of the hydrogen-bonded complexes were evaluated by DSC measurement. Furthermore, photoresponsive behavior of the hydrogen-bonded film was investigated. The hydrogen-bonded film bent toward the irradiation direction of UV light. The photoinduced bending behavior of the hydrogen-bonded film was similar to that of films formed by chemicalbond. In addition, we succeeded in preparation of recyclable films.

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A ferroelectric liquid-crystalline monomer with an azobenzene moiety was used to prepare crosslinked liquid-crystalline polymer (CLP) films with a higher molecular order. CLP films with different molecular alignments were prepared by photopolymerization under various conditions: a smectic C* phase and a smectic A phase. Bending was induced by photoisomerization of azobenzene moieties causing a change in order parameter. Because of low glass transition temperature, this CLP films could bend and revert upon irradiation at 366 nm and >540 nm at room temperature. The contraction force of CLP films with different thichness was measured by thermomechanical analysis.

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We fabricated thin films with gradient refractive index based on cross-linkable liquid crystals for use in organic light-emitting diodes (OLEDs) to reduce the total reflection generated between the emissive layer and the glass substrate. The film was fabricated by photopolymerization of nematic UV-curable liquid crystal in a hybrid cell, in which one side was coated with lecithin to produce a homeotropic alignment, and the other side was spin coated with polyimide and rubbed to obtain a planar alignment. We characterized the refractive index gradient film by polarizing optical microscopy and actinography.

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The crosslinkable oligothiophene was synthesized, and photoresponsive behavior of nematic liquid crystals (LCs) doped with the crosslinkable oligothiophene was investigated. The LC nature and optical properties of these compounds were evaluated. The photoinduced diffraction rings were observed as a result of self-phase modulation, when an Ar+ laser beam at 488 nm was irradiated above the threshold intensity. The number of rings, which shows the degree of the change in alignment, depended on the light intensity. The reoriented LCs were stabilized by photopolymerization with 366-nm light from a high-pressure Hg lamp.

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The photorefractivity of photoconductive-polymer-stabilized ferroelectric liquid crystals (PPS-FLCs) was investigated. The PPS-FLCs were fabricated by photocuring a photoconductive monomer doped in the SmC* phase of a liquid crystal under the application of DC electric field. The electro-optical properties were affected by the photopolymerization of the monomer. The asymmetric energy exchange signal was stabilized in PPS-FLC materials.

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Azobenzene liquid-crystalline polymers containing a thienylacetylene moiety in the side chain were synthesized and their thermal and optical properties were investigated. The polymers obtained exhibited an LC phase in a wide temperature range. The change in transmittance of probe light through a pair of crossed polarizers was studied by irradiation of the film with an Ar+ laser beam at 488 nm. The birefringence decreased due to the change in alignment induced by trans-cis photoisomerization of the azobenzene moiety. The polymer film showed the high birefringence value.

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Diffraction properties of holographic gratings recorded in azo-dye-doped liquid crystal material with homogeneous orientation were studied. The gratings were recorded by using two polarized pump beams. The properties were investigated from the point of view of relationships between incident polarizations and diffracted polarizations. The results indicate that the molecular orientation distribution was induced not only for the direction of the grating vector but also for the thickness direction of the grating. The estimated reorientation distribution could be explained by the polarization modulation of the recording light for the propagation direction, which is caused by the uniaxial optical anisotropy of the oriented material.

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We measured the surface of the ion-beam-irradiated polyimide films with the 45-degree incident angle by means of the AFM. The AFM image analysis revealed the modification of the polyimide surface which corresponds to about 25-nm and 50-nm pitch microgrooves. This modification is remarkable in the in-plane direction (X axis) perpendicular to the ion beam irradiation direction (Y axis). In order to check liquid crystal (LC) alignment, a smectic LC with INAC phase sequence was injected. Increasing the surface modification, the LC alignment direction changed from the Y axis to the X axis. In the case of excess ion beam dosage, this microgroove structure determines the LC alignment.

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Optically compensated bend (OCB) mode LCD requires initial transition from a splay alignment to a bend alignment before operation. In this study, we discussed the creation of nuclei of the transition and velocity of disclination line in case of varying pretilt angle. As a result, it is clarified that minimum of required twist angle for the nuclei and the velocity of the disclination line decreased as the pretilt angle increased.

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Polymethacrylate liquid crystalline polymer comprising 4-oxycinnnamic acid (Figure 1) was synthesized and characterized. In this polymer, liquid crystalline nature was generated due to the hydrogen(H)-bonds between two cinnamic acid groups. The molecular orientation was induced by linearly polarized ultraviolet (LPUV) light and heat-treatment under liquid crystal temperature of the film. The orientation behavior of the film is determined by polarization UV and FTIR spectroscopies. Furthermore, homogeneous alignment control of low-molecular liquid crystals on films is demonstrated both perpendicular and parallel to the electric vector by adjusting the exposure energy.

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We synthesized a new photo-cross-linkable liquid crystalline copolymer (CPLC) for the photoalignment layer for LCs, and demonstrated a LC alignment behavior. CPLC films were aligned parallel to E when exposing to 0.35~ 0.5J/cm² doses for both A- and B-films. Moreover, films exhibits thermal stability up to 250?C. Using these photoalignment layers, anti-parallel LC cells were fabricated. LC alignment direction was parallel to the reorientation direction of the photoalignment layer. Additionaly, azimuthal anchoring energy of the alignment layer was greater than that of the conventional PVCi photoalignment layer.

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In order to generate stable and uniform pretilt angle below 85 deg. for vertical LC alignment, a polymer-stabilized (PS) technique with a bias voltage (BPS), which is combined with a photo-alignment method, has been proposed. By the BPS method using a LC medium doped with a small amount of UV-curable LC monomer (<2wt%), we achieve a very low pretilt angle as much as 80deg. showing an extreme stability against temperature changes. This method is applied to the fabrication of vertically-aligned (VA)-STN-LCDs, and we succeed in obtaining very steep voltage vs. transmittance (VT) characteristics, which enables the VA-STN-LCD to provide a high multiplexing capability.

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Recently, field sequential colour liquid crystal displays (FSC-LCDs) have been developed. They have several advantages, but can result in artefacts such as colour mixing, gamma mismatch and colour break-up by using conventional driving method. We have developed a 9-inch diagonal FSC-LCD using optically compensated bend (OCB) mode and a new driving technique which consists of black and white insertion driving. This new driving method enables us to achieve a high transmittance of 16% and a high contrast ratio of over 600:1 without causing problems such as colour mixing, gamma mismatch or colour break-up.

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LCD doped with the nanoparticles of metal such as Ag/Pd exhibit a frequency modulation and fast switching; these phenomena are well quantitatively understood and explained by an equivalent circuit model for the Maxwell-Wagner effect. LCDs doped with inorganic nanoparticles such as MgO exhibit low voltage operation and based on the modification of the order parameter.

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We have prepared a novel dichiral compound possessing an asymmetric axis and an asymmetric carbon, and investigated helical senses and pitch values induced by the compound in the chiral nematic mixture. The induced helical structures were found to depend on the host structure. The chirality transfer in the present system is discussed based on molecular recognition between the dichiral compound and the host material.

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Novel dimesogenic and trimesogenic compounds were prepared and their physical properties were investigated. The compounds exhibited N and SmA phases. Dielectric anisotropy induced by the dimesogenic compound in the N mixture was found to depend on the parity of the central spacer. We discuss structural effects of the novel liquid crystalline oligomers on the phase transition behavior and electro-optical properties.

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The liquid crystal dimer is composed of two mesogenic groups linked by a flexible spacer. It shows interesting structural properties i.e. odd-even effect and segregation of spacer and terminal alkyl chain. While the series of mOAMnAMOm notably exhibit these properties, the odd numbered mOAMnAMOm with a pendent group in the spacer part form a SmA phase. In this SmA, the molecules are likely to take a U-shaped conformation .

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Achiral twin dimer mOAM5AMOm with the Shiff's base mesogenic unit forms distinct chiral phase. The phase which has chiral structure is abbreviated Crblue phase. The Crblue phase forms two different optical rotational domains. Interestingly the size and shape of the chiral domains of Crblue phase are not changed at cycling between Crblue phase and higher SmCAb phase under suitable thermal condition. The structure of Crblue phase and relation between Crblue and SmCAb have studied.

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We describe a strategy of the anisotropic photoreaction and molecular reorientation of photosensitive materials, the mechanism of photoinduced reorientation of our recent results from the study of the photo-cross-linkable polymer liquid crystals that can generate photoinduced molecular reorientation.

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About a decade ago, Terentjev and Warner theoretically described the coupling between elastic deformation and the SmC order parameter for the limiting situation of small distortions. These predictions have not been experimentally verified due to the lack of monodomain samples. Recently, however, Hiraoka et al, succeeded in obtaining these samples with macroscopic C2 symmetry of the unwound SmC* state, and experimentally demonstrated that monodomain samples exhibits spontaneous and reversible biaxial-deformation on heating and cooling where successive phase transitions take place. They confirmed the macroscopic symmetry defined by the shape of the SmC* elastomer film was closely associated with the microscopic local symmetry due to the liquid-crystalline phase, and concluded that the change of the microscopic local symmetry brings the macroscopic symmetry defined by the shape of the SmC* elastomer film. The purpose of this paper is to investigate the details of the mechanism of the deformation behavior, analyzing both of the shape change of the elastomer and the molecular re-alignment during the phase transformation.

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It was found the unusual alignment phenomena of the chiral nematic liquid crystalline mixtures with the chiral dopant having a cyclohexane asymmetric frame. The alignment of the liquid crystalline molecules were changed with temperature. We report the condition for the phenomena.

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The iron(II) compounds [Fe(3Cn-L)2(NCS)2], [Fe(3Cn-bzimpy)2](BF4)2 and the cobalt(II) compounds [Co(Cn-terpy)2](BF4)2 were synthesized and the physical properties of the compounds were characterized by polarizing optical microscopy, differential scanning calorimetry, powder X-ray analysis, magnetic susceptibility and dielectric measurements. The iron(II) compounds [Fe(3Cn-L)2(NCS)2] exhibited spin-crossover, photo-induced spin transition and liquid-crystal properties in a single molecule. The iron(II) compounds [Fe(3Cn-bzimpy)2](BF4)2 exhibited spin-crossover and ferroelectric properties. The cobalt(II) compounds [Co(Cn-terpy)2](BF4)2 exhibited a synchronization between the spin-crossover and mesophase transitions. The compounds with multi-function are important in the development of molecular switches and optical materials.

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The domain shapes and orientational structure of DPPC monolayers were characterized by Brewster angle microscopy and Maxwell displacement current to investigate domain shapes comprised of chiral molecules. It was observed that, in the course of monolayer compression, the domain increases size and turn into asymmetric shape from circular domain. The growth of DPPC domains is discussed in terms of shape equation of monolayer domain.

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The electrostatic energy of monolayer domain comprised of chiral molecules is analyzed taking into account the presence of electric quadrupole moment density in liquid crystal-like phase. Shape equation of such domains is derived using Taylor expansion method. We show that the electric quadrupole moment density contributes as spontaneous curvature, and that such monolayer domains form shapes without mirror symmetry.

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Time responses of a nematic liquid crystal director orientation change are measured by using acoustic or optical method. The responses with an applied voltage are in the order of milliseconds in both methods, while the responses with the voltage removal are quite different. The response with the voltage removal measured by acoustic wave is about a thousand times faster than that measured by light. The explanation is that the acoustic method can measure the director orientation only in the vicinity of the glass/liquid-crystal interface.

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We studied cholestric liquid crystal alignment induced by stretched polymer filaments. The fine polymer filament was fabricated by extending and exfoliating nonwoven cellulose cloth. The filament was sandwiched between glass substrates, and cholesteric liquid crystal was filled in the substrate gap. The polymer surface anchors liquid crystal directors to the filament direction. It was observed that helical axis of cholesteric liquid crystal near the filament was fixed to be perpendicular to the filament direction. The local control of helical alignment using stretched filaments is applicable to electronic paper and photonic band crystal applications.

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We have succeeded in controlling the pretilt angle of liquid crystal (LC) molecules over the whole range from 0 to 90 degrees by using photo-aligned polyimide films. The polyimide contains azobenzene in the backbone structure (Azo-PI) and has side-chains. The photo-alignment treatment was linearly polarized light irradiation at normal incidence followed by oblique angle irradiation of unpolarized light, and it was performed on the corresponding polyamic acid (Azo-PAA) film. By curing the Azo-PAA films, the photo-aligned polyimide films were obtained. The pretilt angle of LC molecules induced by the photo-aligned polyimide films increased as the side-chain content in Azo-PI increased.

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As a useful tool to evaluate the molecular alignment inside a liquid crystal, we applied the crystal rotation method, a conventional technique to determine pretilt angles in calamitic NLCs, to a discotic liquid crystal (DLC) for the first time. The DLC used was a mixture of two DLCs: DLC1 and DLC2 (weight ratio 4:1) as shown in Figure, and was introduced into cells of 100 micrometer thickness. The cell surfaces were coated with PVA and rubbed. The pretilt angles were determined for various rubbing strengths of the alignment layer and at various temperatures. We found that the pretilt angle increases with decreasing rubbing strength and temperature, as shown in Figure.

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It has been reported that the contact angle of isotropic phase droplet (or nematic phase droplet) on the rubbed polyimides (PIs) surface at the clearing temperature is strongly related to the rubbing strength. In this paper, we discuss detailed relationship between the surface order parameter and the contact angle of droplet using polarized IR absorption and birefringence measurement of LC surface layer of homogeneous cell. Based on the result, new model concerning formation of droplet contact angle was established. Additionally, surface layer of the homeotropic alignment LC cell was discussed.

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We devised a new measurement method: the Psi Delta HAN cell (PDH) method, for the surface polar anchoring strength using a hybrid alignment liquid crystal cell. In the PDH method, the alignment distribution of a liquid crystal cell is determined from the numerical fitting of experimental values of the angular dependence of the amplitude ratios and the phase differences that is measured in the perpendicular direction to the alignment plane and that of theoretical values. We measured cell gap dependences of the polar anchoring strengths at the interfaces of a parallel alignment layer and a perpendicular alignment layer. As a result, the polar anchoring strengths are constant to the cell gap, and therefore we confirmed the validity of PDH method.

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By means of an azo-dye layer consists of Brilliant Yellow (BY), we successfully achieved an alignment control of chain-like structures formed with colloidal particles dispersed in liquid-crystals. On diagonal irradiation of the layer with unpolarized ultra-violet light, the chain-like structures exhibited an in-plane rotation toward the irradiated light. At the same time, we observed alignment change of bulk liquid crystal in a polarized optical microscope. Therefore, the photoinduced rotation of the colloidal structures will be responsible to the photoinduced alignment change of the liquid crystal molecules on the azo-dye aligning layer.

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A photochemically tunable photonic crystal was prepared by infiltrating azo-polymer liquid crystal (LC) in a SiO2 inverse opal structure. The SiO2 inverse opal film obtained reflected a light corresponding to the periodicity as well as the refractive indices of the inverse opal structure. Linearly polarized light irradiation shifted the reflection band to longer wavelength more than 15 nm. This is caused by the formation of anisotropic molecular orientation of the azo-polymer. The switched state was stable in the dark, and reversible switching of the reflection band can be achieved by the linearly and circularly polarized light irradiation.

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Patterned surfaces of planer and homeotropic alignment were prepared and multidomaine LC cells with homeotropic / hybrid or homogeneous / hybrid orientations were made. Retardation distributions around the boundary between planer and homeotropic alignment were measured under the voltage application. Optical characteristics and the retardation differential were discussed, since the clearly threshold voltage was not observed in the hybrid orientation domain compared to homogeneous and homeotropic orientation domain.

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Measurement of the polarization state of transmitted light through LCDs is important to characterize the LCDs. Until now, we have constructed an optical system to evaluate static and dynamic phenomena by measuring the polarization state of light. In this study, we will present time-resolved measurement results of the polarization state using a newly-constructed optical system with a wedge-shaped LC modulator.

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The scanning near-field imaging technique has been utilized in a variety of instruments that cover frequencies spanning the microwave-to-optical regions. Recently microwave and millimeter-wave bands scanning near-filed imaging techniques have attracted much attention as useful tools for evaluating dielectric, semiconductor, and metal materials, high special resolution thermography, topographic imaging, characterization of active microwave circuits, and so on. This talk provides an overview of high-frequency scanning near-field microscopy in the microwave and millimeter-wave regions. As an example of the millimeter-wave microscopy, a millimeter-wave microscope system using a metal slit-type probe is presented.

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In this study, we are proposing the CPW type liquid crystal device that can be made by the same sandwich structure with usual liquid crystal cells. This device has a feature that the liquid crystal can be driven only with the CPW electrode, but a large impact appears to the millimeterwave propagation characteristics by combining CPW with the upper electrode substrate. Then, the influence given to the propagation characteristics, the phase modulation characteristics and the electromagnetic field distribution characteristics are examined.

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We develop a transmission line with a floating electrode (FE) arranged on a coplanar waveguide (CPW), and we propose using this transmission line to reduce the decay time of a microwave-band liquid crystal loaded device. Using the proposed CPW-FE structure makes it possible to control both the rise time and decay time by varying the applied bias field, thereby allowing the decay time to be reduced. In the 18 GHz band variable phase shifter we developed, we obtained a rise time of 75 ms and a decay time of 200 ms with a 500µm wide CPW center conductor, a gap of 20 µm between the center conductor and ground plane, and a liquid crystal layer thickness of 50 µm. Under these conditions, the birefringence De¢of the liquid crystal was 0.23.

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A liquid crystal (LC) beam former is a millimeter-wave (MMW) device that can electrically control MMW beam direction and shape by utilizing the feature of LCs that, as in the optical region, permittivity in the MMW range can be varied by application of a control voltage. In a previous design, control of the beam former was limited to one dimension because of the simple structure where LC layers and control electrodes were alternately stacked. In this paper we propose a new structure for two-dimensional beam-steering and shaping where the control electrodes are split into several strips in order to realize a two-dimensional permittivity distribution across the beam former. Experiments are conducted to validate this capability.

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A microwave variable delay line of coplanar wave guide with float electrodes using ferroelectric liquid crystal is discussed. When the polarity of applied voltage to the liquid crystal layer is changed, a phase shift of the microwave is observed and the phase shift is proportional to the frequency of the microwave. The phase shift increases with increasing applied voltage and the rise and decay times of the phase shift decreases with increasing applied voltage. Both response times are less than 1 ms above 120V and a high speed variable microwave phase shifter is achieved.

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Nanoparticle doping nematic liquid crystals are prepared by using ITO and Au nanoparticles . Their loss and refractive index properties are measured in the millimeter-wave region(65-110GHz). There seems to be anisotropic increase in the refractive index properties and the loss properties which is related with some anisotropic phenomena in the LC materials.

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In this study, we measured various materials with millimeter-wave waveguide probe which used 60GHz Gunn diode. In our measurement system, millimeter wave generated by Gunn diode was radiated from the probe to the sample. And the reflected wave was detected by small signal measurement system using lock-in amplifier. In the measurement of the ITO glass substrate, relationship between the resistivity and the detected voltage of the reflection wave was discussed. For the case of the liquid crystal cell measurement, influence of the liquid crystal molecular orientation condition on the detected voltage was explored.

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A TN liquid crystal cell with a shaded aperture is made by applying the four signals on the cell. The transmittance distribution of the cell gives an optical transfer function with a high gain and no phase inversion up to the higher space frequency like Hanning function. The high quality images are obtained by the LC lens shutter in both cases of the Siemens chart and the outdoor scene shots.

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We measure spherical aberration and astigmatism properties of a liquid crystal (LC) lens with an external transparent electrode and eight-divided circularly hole-patterned electrodes. The interference fringe patterns are composed of elliptical fringes and the direction of major axis of the fringes can be rotated by applying the control voltage to each divided-electrode. The spherical aberration and astigmatism properties can also be controlled by adjusting the applied voltages.

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Recently, a fast liquid crystal (LC) lens with stacked structure of thin LC layers has been proposed. The lens power can be maintained due to the stacked LC layers even though thin LC layers are used. Here we report our research on the transient properties of the LC lens with stacked structure. The focus range is expanded by driving the LC cell working as not only a positive lens but also a negative lens. The transient behaviors of the LC cell switching between positive and negative lens are observed, and it is found that the LC lens has a wide focus range, and the switching between positive and negative lens becomes very fast.

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2, 3, 6, 7, 10, 11-hexakis (4-alkyloxy-2, 3, 5, 6-tetrafluorobenzoyloxy) triphenylenes (CnOF4E-TP) were synthesized to study the mesomorphic transition behavior by polarized optical microscope, DSC and XRD techniques in comparison with that of 2, 3, 6, 7, 10, 11-hexakis (4-alkyloxybenzoyloxy) triphenylenes (CnOH4E-TP). It was found that CnOF4E-TPs are likely to exhibit Colh phase having a wide range of temperature. In contrast to that CnOH4E-TPs exhibit exclusively ND phase. It was shown that the introduction of tetrafluorophenyl rings to the peripheral part of triphenylene discotic liquid crystal leads to the strong tendency to stabilize the columnar structure in Colh phase.

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Previously, we have reported the mesomorphic property of monomeric 2-[4-(w-methacryloyloxyalkoxy)benzoyloxy]-5-alkoxytropones and their polymers as well as the corresponding benzenoids. In this paper, we synthesized 2-[4-(w-methacryloyloxyalkoxy)benzoyloxy]-5-(4-alkoxybenzoyloxy)tropones and the related derivatives to investigate their mesomorphic property and thermal behaviors of the polymers.

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Novel triphenylene derivatives possessing polyethylene glycol units as side chains were synthesized and their liquid crystalline behavior was investigated by polarized light optical microscopy (POM), differential scanning calorimetry (DSC), and powder X-ray diffractions (XRD). The compounds exhibited nematic discotic liquid cryatal phases, and some of them showed stable mesophases at room temperature with broad temperature range. Further, we investigated their liquid crystalline behavior with alkaline metal ions.

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Abstract: Discotic liquid crystals are expected to be applied to thin film solar battery, organic TFT and so on, as the organic electronic device materials. Many kinds of discrete donors and acceptors of discotic liquid crystals have been synthesized up to date. However, few discotic liquid crystals bearing both donor and acceptor moieties have been prepared. In this study, we have successfully introduced an acceptor fullerene to a discotic liquid crystalline donor based on phthalocyanine. We wish to report here there results.

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