[in Japanese]

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The optical properties of the liquid crystal (LC) can easily be controlled by applying a relatively low electric field. Then, some applications of LCs to optical devices can be attained in addition to display devices. As the optical devices prepared using the molecular orientation effects in nematic LCs, beginning and details of the development of LC lenses and other LC optical devices studied by our research group are reviewed. Improvements of the LC lens with variable focusing properties and new LC lenses with different structures are reported. LC gratings, polarization conversion devices, quasi-optical devices, optical logic devices and other LC devices are also described.

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We reported that all-organic, chiral nitroxyl radical liquid crystalline (LC) compounds (1), which contain a dichiral nitroxide unit in the core, showed ferroelectricity as well as paramagnetism. In this communication, we report the synthesis, and the electric and magnetic properties of novel LC compounds 2, which are the structural isomers of 1. Racemic or enantiomerically-enriched 2 showed N or N^*, SmA or SmA^*, and/or SmC or SmC^* phases, respectively. In addition, we have discovered that some of compounds 1 and 2 show superparamagnetic properties by which their LC particles are attracted to a magnet.

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We have prepared a homologous series of T-shaped chiral oligomers and investigated effects of the molecular structure on appearance of a blue phase. All T-shaped compounds were found to show the blue phase with a relatively wide temperature range. The lateral substituent, central spacer length and terminal chain length slightly affected the stability of the blue phase. On the other hand, bent-shaped chiral compound did not show the blue phase.

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A novel S-shaped liquid crystal, 4,4'-bis(6-(2-(6-(4-(4-cyanophenyl)phenyloxy)hexyloxy)phenyloxy)hexyloxy)biphenyl, was prepared and the physical properties were investigated. The S-shaped compound possessing cyanobiphenyl moieties exhibited a monotropic nematic phase. The nematic phase was miscible with that of 4-hexyloxy-4'-cyanobiphenyl(6OCB). On the other hand, a binary mixture between the S-shaped compound and 5-octyl-2-(4-hexyloxyphenyl)pyrimidine (8-PYP-6O) showed SmA and unidentified smectic phases. We discuss structural effects of the S-shaped compound on the phase transition behavior.

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We have prepared anisotropic ion-conductors that can transport ions efficiently in a specific direction by using self-assembly of liquid crystals. Complexation of liquid crystalline molecules and isotropic organic electrolytes leads to the formation of liquid crystalline assemblies having phase-segregated structures in nanometer scale. Anisotropic ion conduction has been achieved for macroscopically aligned assemblies.

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New liquid crystalline comb-shaped polymers (LCPs) with hydroxyl groups were synthesized. Their thermal and orientational properties were examined. An epoxy monomer (E5) with a 4-(4-pentylcyclohexyl)phenyl mesogenic group showed a smectic A phase with a focal conic fan texture. LCPs with the 4-(4-pentylcyclohexyl)phenyl mesogenic groups, which was synthesized by the reaction of E5 and polyethyleneimine, exhibited a smectic A phase with focal conic fan and homeotropic textures from glass transition to isotropization temperatures. LCPs with 4-cyanobiphenyl mesogenic groups formed only a nematic phase.

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A nonionic liquid crystal and its ionized family were synthesized. Their thermal and liquid crystalline properties were examined by the polarizing microscopic observation, DSC, and X-ray diffraction measurements. Moreover, binary systems composed of the nonionic and ionic liquid crystals were prepared. The nonionic liquid crystal exhibited a smectic A phase. The ionic family also formed the smectic A phase. The smectic-isotropic phase transition temperature of the ionic family was higher than that of the nonionic family. The liquid crystalline binary systems composed of the nonionic and ionic families showed an induced nematic phase.

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The present study reveals a crucial role of peripheral alkyl chains in the formation of stable columnar mesophases.

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We synthesized 5-substituted troponyl cholesten-3-carboxylates and carboxyamides to investigate their mesomorphic property. The troponoids with halogens and cyano groups at the 5 position showed chiral N and SmA phases. The 5-alkoxytroponyl derivatives, however, showed a TGBA phase as well as chiral N and SmA phases. The results will be discussed by comparing with the thermal behaviors of the corresponding benzenoids.

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We have composed a hybrid photonic crystal with ferroelecric liquid crystal by inducing the ferroeletric liquid crystal between dielectric multilayers consisted of SiO₂ and TiO₂. We have investigated laser action in the hybrid photonic crystal by light excitation, and achieved single-mode laser action. We have compared the lasing threshold between the hybrid photonic crystal and simple FLC without the dielectric multilayers, and observed the lasing threshold of the hybrid photonic crystal was 10³ times lower than that of the simple FLC without dielectric multilayers.

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We propose a bottom-up method to introduce chiral defects in Cholesteric liquid crystals (ChLCs), which are structural defects where the helical pitch of the ChLC is modulated over a narrow region. Our method is based on performing high-resolution laser-assisted photo-fabrication in a photo-polymeric ChLC material, which causes a literal "modification" of the helix. We succeeded in introducing single or multi-defect modes in the helical structure, depending on the lithography conditions.

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Until recently, a lot of research on lasing in cholesteric liquid crystals (CLCs) have been made. However, there are few reports about a CLCs laser whose tuning range covers over 200nm. Here, we introduced a spatial helical-pitch-gradient structure of CLCs by the gradient of chiral dopant concentration to acquire wide-range controllability of the helical pitch. Also, two dyes were doped, and exploited energy transfer between them for wide spectral range of fluorescent dyes. Lasing emission wavelength covers almost whole visible light region except for the vicinity of 500nm without changing the excitation wavelength.

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We report on the reduction of a lasing threshold by using three-dimensional photonic structure of blue phase (BP). In cooling process, a single crystal of BP I grew in the (110) orientation under electric field to become more than 1 cm in diameter. The central wavelength and full width of the photonic band were 592 nm and 10 nm, respectively. The sample was doped with a fluorescent dye, Pyrromethene597, which had a peak emission in the vicinity of the band edge, and excited at 530 nm by a fs-OPA system. Although a fluorescent component of the left-circularly polarization was restrained in photonic bandgap, laser oscillation of the left-circularly polarization occurred at the band edge, 597 nm. The lasing threshold of BP I was found to be half of a chiral nematic phase.

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A flexible microcavity organic light emitting diode (OLED) was fabricated and the emitting characteristics were examined. A pair of right- and left-handed CLC films were attached to the microcavity OLED. The introduction of the CLC film improved both the emission bandwidth and directionality, preserving the turn-on voltage and maximum brightness.

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I review liquid crystal composites in soft matter.

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The polymer-stabilized blue phases with a cubic structure on the order of optical wavelength were observed by the confocal laser scanning microscope. The interval of a stripe pattern found in the (110) plane of the polymer-stabilized blue phase was about 100 nm, which agreed to the interval of the ordered double twisted cylinders. The focal distance was varied by applied electric field due to the field-induced change in the refractive index of the polymer-stabilized blue phase.

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Liquid state has highest symmetry, so the X-ray diffraction pattern is completely uniform and symmetric in the space. Thus, space has complete spherical isotropic symmetry in liquid state. On the contrary, if temperature goes down to the solid phase or liquid crystalline phase, special regularity of the "order" breaks the symmetry of the space. We have found the novel isotropic smectic blue phase (SmBPIso), which show the appearance of the "Ordering" does not break the macroscopic "symmetry" of the space. We call this is "Isotropic order". Recently we have investigated the dynamics of the SmBPIso by pulse laser light induced color shift and dynamic light scattering.

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Swelling and phase behaviors of monodomain liquid crystal elasotmers (LCE) under constant loads along the director are investigated. The N-I transition temperature increases with an increase in load. The applied load drives a considerable further swelling in the isotropic state, whereas the load-induced swelling is significantly suppressed in the nematic state. The results obtained are compared with the theoretical prediction.

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Slow dynamics of strain recovery for nematic elastomers with polydomain textures is investigated. The polydomain nematic elastomer formed in the isotropic phase exhibits much slower relaxation than that made in the polydomain nematic phase, while they show no appreciable difference in equilibrium properties such as the degree of swelling and phase transition temperature.

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We investigated thermotropic liquid crystalline mixtures consisting of a perfluorinated liquid crystal and liquid crystals with mesogenic cyanobiphenyl core. The phase diagrams of the liquid crystalline mixtures were constructed from morphological observations using a polarized optical microscope with a hot stage. Improving stability of SmA phase was found on the mixtures with a linear liquid crystal although that was not with a branched liquid crystal. Microphase segregation of perfluorinated alkyl chain and alkyl side-chain as well as excluded volume effect are most likely to affect the phase transition behavior of the liquid crystalline mixtures.

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We performed experimental investigations on micro-actuators driven by back-flow of nematic liquid crystals. First, we measured velocity profiles of back-flow between parallel plates, and compared those data with numerical predictions. The measured profiles agreed qualitatively with the calculation. Next, we attempted to move one of parallel glass plates, whose mass was 0.035g, by the flow induced by rectangular wave voltage. The moved distances of the plate for 25s reached 135 micrometers when the frequency of the voltage was 0.1Hz and 1Hz, however it was only 70 micrometers in the case of the frequency of 10Hz.

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We discuss how the equations describing the dynamics of an order parameter based on a continuum theory should be numerically implemented when rigid, impenetrable walls are present. In this study, we pay particular attention to the cases of non-conserved order parameters. For concreteness, clarity and simplicity, we consider a typical example, the dynamics of a nematic liquid crystal cell under an in-plane electric field, where surface anchoring plays a crucial role. In the discretized equation of the dynamics of the order parameter (azimuthal angle) just at the surface, there appears a contribution from the bulk energy that is proportional to the grid spacing and absent in a usual discretization. We show that our discretization scheme is consistent in the sense that it can yield the identical dynamical behavior irrespective of the choice of the grid spacing. We also demonstrate that our scheme is reliable even when the grid spacing is relatively large.

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It is known that there are three types of cubic structures in lyotropic liquid crystals. However their thermodynamic characteristics have not been clarified. The present work focuses on the monoolein/water system which shows several phases including two cubic phases, Ia3d and Pn3m, as well as a lamellar one. Their heat capacities were measured for various compositions by adiabatic calorimetry. The relations among those phases are discussed from thermodynamic point of view.

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1,2-Bis(4'-n-alkoxybenzoyl)hydrazines (BABH-n, n is the number of carbon atoms in the alkyl chain) showed Cub phases with Ia3d and Im3m symmetries with lengthening the alkyl chain. Especially, the members of n=13 and 16 exhibited the Cub-Cub phase transition with changing the temperature. The details of the phase transition behaviors are presented.

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Thermotropic cubic mesogens BABH-n exhibit two bicontinuous types of cubic phases with Ia3d and Im3m symmetries, depending on the temperature and alkyl chain length. Part 2 will discuss that systematic studies with respect to the chain length n provide not only the details of the phase behaviors but also usuful information on the packing structure at the molecular level, that is, the position of the alkyl chains, when observed scattering amplitudes are carefully compared with the computed ones for corresponding triply periodic surfaces.

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A new series of double-decker cerium phthalocyanine materials substituted by thioalkyl groups of different lengths (CnH2n+1S- with n= 8, 10, 12, 14, 16 & 18) were prepared and their mesomorphic phase transition behaviour was investigated. All homologues exhibit a Colh mesophase. Interestingly, the thermal stability of these columnar mesophases is enhanced compared to those of previously reported double-decker lutetium, terbium or europium phthalocyanine complexes. This could be explained by the unique feature of the cerium phthalocyanine material having both dianionic ligand of equivalent structure.

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Amphiphilic liquid-crystalline oligomers composed of a semiperfluorinated alkyl chain and cyanobiphenyl mesogenic moieties were prepared. Their physical properties were investigated by means of optical microscopy, differential scanning calorimetry and X-ray diffraction measurements. Increasing the number of the cyanobiphenyl moiety, the oligomers were found to show an unusual phase sequence of lamellar-columnar-bicontinuous cubic phases. Results of XRD study suggest that the smectic A phase of the oligomer with a SmA to Cub phase transition has a fluctuated layer structure. We discuss effects of the molecular structure on appearance of the columnar and cubic phases of the novel liquid crystal oligomers.

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An internal DC voltage generated in a LC cell (residual DC voltage) brings image sticking phenomena on LCDs. It is known that the residual DC voltage strongly relates to impurity ions in the cell. In this study, we investigated a relation of absorption and desorption process of the ions to a surface between LC phase and alignment layer with the residual DC voltage. Finally, we proposed a suitable evaluation method of materials for LCDs from the point of the image sticking.

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We have study the vertical LC alignment control for realizing high-performance LC projectors using VA-LC panels, in which LC alignment control on an inorganic alignment layer, having excellent stability against light exposure, was an important target. Estimation of the polar anchoring energy is one of important parameters to characterize vertical LC alignment, but few studies on the topic have been reported. In this study, we mainly present the results of the polar anchoring energy of LCs on inorganic vertical alignment layers.

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Image sticking phenomena is one of the most important issues on LCD especially TVs,etc. It is well known image sticking is one of the display defects induced by the residual DC voltage. Analysis of the cause material of display defects especially temporary defect, image sticking on LCD is very difficult and not reported. I developed the new analysis method to resolve the problem of display defects on LCD and reported at LC meeting,IDW. Here I will introduce the analysis technique to analyze the cause materials that induce image sticking on Lcd and show one example of results.

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A nematic liquid crystal (LC) could be homeotropically oriented on an anodic porous alumina (APA) film prepared by anodizing Al. The orientation mechanism is based on a nanostructure that extends perpendicularly against a substrate. In this paper, the effects of the formation process of aluminum films on LC molecular orientation characteristic are examined. In case of the obliquely evaporated aluminum film, surface topography of the anodic oxide film is different from it of normally evaporated films. And, It have examined to give Pretilt from surface topography.

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Motion blur in LCD is caused by the response of liquid crystal and hold-type driving method. Moving Picture Response Time (MPRT)1) ,which is one of the basic psychophysical estimation, measures an average width of blurs. This method comprehensively evaluates the causes of the blur. However we found that visualization of the blur is expressed not only the width but color, sharpness of object and ratio of blur area. We evaluated and analyze the relation between visualization of the motion blur and physical properties (image properties and panel characteristics) at a CRT display and several types of LCDs, and performed subjective evaluation with various images.

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We have studied patience limit and just noticeable difference for motion blurs in FPDs by subjective evaluation with simulated motion images. The results of the evaluation show dependence on not only the width of blurs but the distortion of response waveform and contrast of the evaluated pictures and so on.

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Recently, a Large-size LCD requires wide viewing angles and high contrast ratios. For this reason, liquid crystal standard modes with wide viewing angles and high contrast ratios are in use now, such as IPS mode and VA mode. However, also in those modes, the polarizer induces the problem of the viewing angle dependence. In this research, we uses the optical film with the characteristic of negative A-Plate, and investigates reducing the viewing angle dependence from crossed polarizers.

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We have developed a super wide-view polarizer with wide wavelength range. By using a uniaxial film as a protection film of polarizer and two biaxial compensation films, we realized a high contrast ratio in a wide viewing angle range.

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Liquid crystal displays (LCDs) have been rapidly developed. However, engineers are still seeking new modes, which overcome remaining problems. The reported LCD mode is totally new and can achieve fast response time, high contrast, wide viewing angle, continuous gray level. This display is based on the unique property of the banana shaped LCs. LC molecules exhibit a smectic A-like phase. Because of the bend of the molecules, they do not freely rotate about their long axes, so that quasi-long range order of molecular dipole orientation emerges and the resulting polarization responds to an applied electric field. This order was examined by SHG and analyzed based on 2D Langevin process.

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A nematic (N) liquid crystal microcapsule is considered to seldom be applied except optical dispersion control type tone light glass. With a last report Microcapsule-izing of liquid crystal, Paying attention to the ability to make the liquid crystal material from which character differs intermingled, the basic characteristics, such as a voltage response of N liquid crystal microcapsule (Encapsulated Nematic LC:ENLC), were reported. The possibility of the application to the scattered-about type element of ENLC (ENpLC, ENnLC) which used N liquid crystal material is reported.

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The three-dimensional alignment technique for liquid crystal devices is presented that consists of polymer walls made from UV-curable monomers that are oriented by an electric field while cured with a spatially patterned UV light source. From the observations of polymer wall by using polarizing Raman scattering microscopy, it was found that the polymer alignment depended on rubbing direction on two-substrates and applied electric field in photo-polymerization. This technique provides defined boundary conditions of the liquid director field in three dimensions.

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Generally, thermotropic liquid crystal is used in two glass plates. In this study, thermotropic liquid crystal membrane was produced in distilled water successfully. To make the membrane, Lecithin derived from an egg was employed as surface-active agent. An electrooptic response of the membrane was measured using crossed polarizing optical system. In addition, living cells (L929) derived from a mouse have been cultured on the membrane successfully. In the future, we hope to apply this membrane for living body.

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We have performed the electric control of random lasing in a dye-doped smectic A liquid crystal. The liquid crystal used this study was a mixture of 4'-octyloxy-4-biphenylcarbonitrile and a chiral dopant, S1011 (2wt%). As a fluorescent dye, pyrromethene597 was doped in this liquid crystal at a concentration of 0.7 wt%. With the application of an electric field, when the excitation energy increased, the emission abruptly intensified and the bandwidth drastically shrunk. This random lasing can be controlled by the electric field with a threshold of 4 V/micron. In contrast to the previous report by Morris et al., our sample showed nonlinear amplification even in the electric field induced homeotropic state.

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Electro-optic effects of a cubic phase liquid crystal compound 1,2-bis-[4-n-octyloxy-benzoyl]-hydrazine (BABH8) in Kerr cell geometry are reported. We found cubic phase of BABH8 inactive to AC electric-fields in the Kerr cell geometry at least up to E=7V/u m, i.e. having very small Kerr constants. There was AC electric-field response in the BABH8 smectic C phase which exhibits that BABH8 molecule itself has electric field coupling ability, but that is inactivated in the cubic phase. These behavior could be explained with the small structural unit size of the Cub phases.

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Recently Lee et al. found that the chiral analogues of the conventional bent-core mesogens, P-n-O-PIMB(n-2)^* and P-n-O-PIMB(n-2)^*-(n-4)O, exhibit the odd-even behavior for the emergence of ferroelectric (F; even n) and antiferroelectric (AF; odd n) B2 phases. Nishida et al. also found in 1:1 binary mixtures that the phase structure is governed by the compound with longer end chains. In this study, we examined the detailed phase structures of two binary mixtures; i.e., P-8-O-PIMB6^*-4O/P-9-O-PIMB7^*-5O (P8/P9) and P-9-O-PIMB7^*-5O /P-10-O-PIMB8^*-6O (P9/P10) by means of texture observations and second harmonic generation (SHG) measurements. The phase structures are determined by very delicate balance of interactions stabilizing F and AF states.

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Measurements of dielectric dispersion have been carried out over a frequency range of 1 Hz to 100 kHz on 8422[2F3] and TSiKN65 which are liquid crystals showing de Vries SmA*-SmC* phase transiton. The strength and relaxation frequency of the main dispersion have been studied. In the SmA* phase, it was found that the strength of the dispersion increases significantly on approaching the transition temperature, while the relaxation frequency lowers dramatically. We also plan to decide and discuss critical exponent values.

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Dynamic behaviors of ferroelectric liquid crystal molecules for applied electric field were examined through temporal and spatial changes of conoscopic figures observed with a time resolution of 0.1 [ms]. The observed conoscopic figures were compared with simulated figures using a 4x4 matrix method and the Landau-Khalatonikov equation. The molecules displaced from inside of the helical structure to outside with duration of applied electric field, i.e. the layer positions of the fastest velocity of the liquid crystal molecules were 333,389 at 0.1 [ms] and 31,691 at 2.1 [ms].

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The antiferroelectric hexatic phase observed below antiferroelectric SmCA* has so far been considered to have the same anticlinic structure as that in SmCA*. The orientational order parameter determined by infrared spectroscopy unambiguously deny the previous view and concludes that molecular long axes are not tilted from the SmA layer normal, allowing us to propose a novel model: The phase can be identified as non-tilted modulated HxB* and the electric-field-induced phase transition from this phase to tilted ferroelectric HxI* can be considered as the giant electroclinic effect due to the opening of closed modulation loops.

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