Ionic liquid crystalline materials with ammonium ions and their nonionic family were synthesized. Their thermal and orientational properties were examined. The ionic liquid crystalline materials exhibited asmectic A and smectic C phases. In the smectic A phase, a focal conic fan texture was observed. By cooling from the smectic A phase to a smectic C phase, a schlieren texture was formed. The nonionic liquid crystalline materials exhibited thermotropic liquid crystalline phases such as nematic, smectic A, smectic C, and columar phases.

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Ionic interactions act effectively as a driving force for the liquid crystal formation. In many cases, the ionic interactions lead to the formation of layer structures with enhanced thermal stability. The ionic interactions are also useful to the complexation of polyamine and carboxylate groups. In this study, thermotoropic liquid crystalline ion complexes were synthesized by the proton-transfer reaction of a malonate derivative with a mesogenic unit and an amine group (polyamine or diethanolamine). Their phase trasitions and orientational properties were examined. The liquid crystalline ion complexes, having a diethanolamine group, exhibited hexagonal columnar and smectic A phases. On the other hand, the polyamine containing liquid crystalline ion complexes formed a smectic A phase. The orientational structures were examined by the X-ray diffraction measurement.

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Liquid Crystalline Blue Phases (BPs) attract interest due to their great potential for advanced applications to next generation liquid crystal displays and tunable photonic liquid crystals. The problem of the narrow temperature range in BPs has been resolved by polymer-stabilized blue phases1). However, it is difficult to vary their photonic bands by an external field because of fixed BP lattice. Here we report a new method to broaden the stable temperature range of BPs without using polymer-stabilizing effect. In this study, we investigated a liquid crystllinity and elastic constants of the novel dendritic molecules. The temperature ranges in BPs with the novel dendritic molecules are also examined.

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Blue phases generally appear at narrow temperature range between chiral nematic phase and Iso phase. There are three types of blue phases, BPI, BPII and BPIII with increasing temperature, their structures are different. BPI and BPII are body centered cubic and simple cubic, respectively, but the structure of BPIII is not yet clear. Because of cubic lattice, blue phases are optically isotropic and have chiral pitches, which are related to the lattice constants of the three-dimensional structures. Electro-optic properties of blue phases are well explained by Kerr effect. Kerr constant, K, was known as a dominant parameter of Kerr effect. In this study, we present the relation between electro-optic properties and chiral pitches.

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We successfully developed the ferroelectric columnar liquid crystal which possesses spontaneous polarization along its columnar direction.

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Liquid crystalline ureas were synthesized and characterized. Their thermotropic behaviors were identified by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), powder X-ray diffraction (XRD). The compounds exhibited a rectangular and hexagonal columnar phases. The switching experiments indicated a ferroelectric switching in their hexagonal phases. The mechanism of the switching and the structural effects for their liquid crystallinity and switching response were investigated.

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In this study, we have designed and synthesized liquid-crystalline (LC) molecules having diol moieties. Self-organization of the complexes of the LC materials and ionic liquids led to the formation of columnar LC phases. Furthermore, these LC complexes showed anisotropic ion conduction behavior.

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2,7,12-tris(n-octyloxy)truxene (TR(OC8)3) and its derivatives which was introduced hydroxy or methoxy groups to 3,8,13 were studied on charge carrier mobility correlated to the mesomorphism. Both derivatives exhibit a hexagonal columnar (Col_h) mesophase as well as TR(OC8)3. The introduction of hydroxy or methoxy groups leads to the increase of thermal stability of mesophase in comparison to TR(OC8)3. TOF measurements of carrier mobility were carried out to show that the observed mobility is in the order of 10^-2 cm² V^-1 s^-1 in the mesophase.

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It has been reported that if a shear flow is applied in the nematic phase of 8CB, some shear-induced structures are formed. To clarify these structures in more detail, temperature dependence of the viscosity and dielectric permittivity, transient dielectric response after the application of the shear flow, and frequency dependence of dielectric permittivity were measured. In each shear-induced structural region, characteristic behaviors were observed. These results will be discussed based on the fluctuation of the smectic A structure developed in the nematic phase.

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In the nematic phase of 5CB, nonlinear dielectric properties induced by a shear flow were measured. The results show that a dielectric dispersion is observed in the shear-modified 3rd order dielectric constants and the peak of the imaginary part shifts to higher-frequencies with increasing the shear rate and the temperature. These results will be discussed from the motion of the director under the shear and the electric field.

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We investigate what kind of ordered structures a liquid crystal can show when it is confined in a thin cell, when the most stable phase of the liquid crystal in the bulk is a cholesteric blue phase. Our study is based on a numerical calculation using a Landau-de Gennes theory in terms of a second-rank tensor as an order parameter. We show that topological defects can form several ordered structures that have not been found in previous studies on liquid crystals.

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It is known that a cholesteric blue phase is stabilized, that is, the temperature range of its stability is widened, by introducing a guest component such as polymers. This stabilization is supposed to be attributable to the replacement of defect core regions of a liquid crystal with high free energy density by the guest component. In the present study, we discuss the validity of this idea quantitatively by a numerical calculation using a Landau-de Gennes theory. We show that a small amount of a guest component indeed widens the temperature range of stable blue phase substantially.

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It is well known that a disclination of topological charge -1/2 can be continuously transformed to a +1/2 one via a twist disclination. However, there have been no discussions on how this transformation can be realized. In the present study, we show, by a numerical calculation based on a Landau-de Gennes theory, that this transition is indeed possible in a cholesteric blue phase (a regular array of -1/2 disclinations) under an electric field.

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Temperature range of cholesteric blue phases (BP) was expanded by doping metal nanoparticles such as gold, silver and palladium. Expansion of the temperature range was observed during both cooling and heating processes, and the effect was greater for BP II than for BP I. Stabilization of the BP is believed to be caused by the spherical metal nanoparticles being trapped in the disclination lines and the volume and the energy associated with the disclination lines being reduced.

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Anomalous deformations of smectic bubbles take place under DC electric fields. In the deformation, there are two types. Under low electric field, bubbles were elongated along the fields and stabilized into the constant size in the equilibrium, while under high field, dynamic oscillation replaces. A simple balance equation including electrostatic force & surface tension describes the static and the dynamic deformations quantitatively and semi-quantitatively, respectively. The result shows smectic bubble deformations can be used to visualize such invisible properties of LC films as conductivity, capacitance and surface tension.

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We have investigated mechanical properties of a smectic-A liquid crystal (8CB) whose yield stress can be controlled with electric field strength and its current type. Dynamic viscoelasticity was measured under conditions of small strain amplitude and the measurement was repeated after 0.1 strain amplitude was applied. When a higher dc electric field was applied, higher viscoelastisity was obtained but it became lower in the repeated measurement. Under lower dc electric field conditions, the viscoelasticity was not so high and the influence of the repetition was not clear. It is considered that electroconvections generated in the cooling processes affect the order of the layered structure of smectic liquid crystal. The structures obtained with ac electric conditions showed very low viscoelasticity.

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The liquid crystal blue phase is a phase in which the liquid crystal director self-organizes into a three-dimensional periodic structure with a peridiocity of a few hundred nanometers. While they are potentially fascinating electro-optic materials, the understanding of their optical properties is limited, mainly because of their complex director distribution. Blue phases are commonly believed to exhibit selective reflection similar to the cholesteric phase, however, a more natural phenomenon that can be expected by considering the complex spatial distribution of the dielectric tensor is a reflection band that is polarization-independent. In this presentation, we will report results of our investigation of this problem of Bragg reflection in blue phases, undertaken using both experimental and theoretical methods.

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We have demonstrated memory and rewritable bistable devices based on an anchoring transition of a nematic liquid crystal on a perfluoropolymer surface. Spontaneous orientation changes between planar and homeotropic occur on cooling and heating with a large temperature hysteresis. Photo (heat) addressing is possible from homeotropic to planar using dye-doped samples. Orientation switching also occurs by applying an electric field.

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It was found that mesogenic triphenylenes with six long-chain azobenzene units exhibit different mesomorphisms depending on the linkage groups between triphenylene and azobenzen units. Furthermore, some homologues show layered smectic and stacking columnar phases of which orientational orders of molecules are formed by the rod-like (calamitic) and disc-like(discotic) shapes of molecules, respectively. It was also found that the C14 homologue is a first mesogen which exhibits multiple phase transitions among Col, Sm and Iso phases depending on the photo intensity to cause trans-cis isomeirzation of the azobenzene units.

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Manipulation of micro objects using fluids has attracted a lot of attention because controlled motion of micro- / nano-scale objects on surface is an important step toward developing micro- / nano-machine. In this study, liquid crystalline(LC) films containing different nematic LC and photo-responsive azobenzene compounds were prepared, and glass rods with diameter of ca.7m were put on the films. UV or Visible light irradiation caused motion of glass rods. The effect of light intensity, temperature, and host molecule on the motion of the glass rods on the LC film have been investigated and discussed.

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A multi-bilayered mirror is one of one-dimensional photonic crystals showing photonic band gap, leading to reflection of color depending on a layer thickness and refractive indices of components. In this study, the multi-bilayered mirrors were prepared by spin coating of azobenzene liquid crysyal polymer and polyvinyl alcohol. The orientation of azobenzene groups can be controlled by the irradiation of light or annealing, and consequently change in the birefringence of the azo-polymer is induced. We will discuss control of the structural color with respect to the photo-induced change in molecular orientation of azobenzene side groups.

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We attempted to develop photomobile materials based on main-chain liquid-crystalline polymers for improvement of photomobile property and mechanical strength of photomobile materials. The liquid-crystalline polymers with azobenzenes in the main chain of polymers were prepared. Effect of spacer length and substituent groups on liquid-crystalline property of the polymers was investigated. The main-chain azobenzene liquid-crystalline polymers were crosslinked and applied to the photomobile materials.

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Crosslinked liquid-crystalline polymers prepared from triphenylene derivatives with azobenzene moieties showed anisotropic deformation induced by photoirradiation. In this study, we synthesized a variety of triphenylene derivatives with azobenzene moieties and evaluated their mesomorphic properties. We investigated photomobile property of the triphenylene derivatives crosslinked by photopolymerization.

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Single-walled carbon nanotubes (SWNTs) were dispersed as a filler in polymers to improve mechanical strength of the polymers. Mechanical strength of photomobile polymer materials was expected to increase by complexation of azobenzene liquid-crystalline polymers and SWNTs. Mechanical properties and photoresponsive behavior of the polymer composites were investigated in various shapes.

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Molecular alignment and carrier transport characteristics of a discotic liquid crystal having a high carrier mobility have been investigated. It has been found that this material shows an anomalous molecular alignment.

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Recently, high carrier mobility in the order of 10^-1 cm²/Vs has been shown for highly ordered liquid crystal semiconductors which is comparable to that of amorphous silicon. However, 1,4,8,11,15,18,22,25-octaoctylphthalocyanine was reported to have a high carrier mobility in the order of 10^-1 cm²/Vs even for the Col_hd) mesophase. In this work, carrier mobility behavior of 1,4,8,11,15,18,22,25-octaalkylphthalocyanine homologues were studied for both Colhd and crystal phases by a TOF technique. High carrier mobility of 1.1 cm²/Vs was obtained in the crystal phase of the hexyl homologue in addition to the mobility in Col_hd) mesophase with 10^-1 cm²/Vs.

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Highly polarized polymer-based light emitting diodes (PLEDs) can be fabricated by using a light-emitting liquid-crystalline (LC) polymer, because light-emitting LC polymers, such as poly (9,9-dioctylfluorenyl-2,7-diyl) (PFO), can be aligned with a high degree of alignment, with the help of a proper alignment layer. The polarization ratio and the spectral shape of the light emitted from polarized PLEDs depend on thickness of the light-emitting LC layer, whose refractive indices are anisotropic. This thickness dependence is explained by the optical interference effect taking account of birefringence of the light-emitting layer.

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We consider the influence of the carrier-dipole interaction on the electronic conduction in liquid crystals. We focus on the orientational order parameter and the translational order parameter which are basic order parameters in liquid crystals. The randomly orientated and located molecular dipoles are limited by their molecular order. Based on these concepts we establish the model to evaluate the randomness of the dipolar Coulomb potential for charge carriers depending on these order parameters in order to figure out the mechanism of hopping conduction. This is important factor for thermal activation process of the electronic-conduction in liquid crystals.

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We have investigated charge doping for a liquid crystalline organic-semiconductor using microphase separation of charge dopants. The polyaniline was selected for a hole dopant. It increased the conductivity of a host terthiophene derivative of 8-TTP-8, as a function of its concentration, while the charge carrier transport properties were not affected by the doping at all. In addition, the dopant affected neither conductivity nor hole transport properties when the host material was phenylnaphthalene derivative. These results strongly support that the charge doping was achieved without any degradation of charge transport properties of the host 8-TTP-8 due to the phase-separated doping of polyaniline. Furthermore, we successfully applied the present result to the improvement of contact resistance in the FET fabricated with 8-TTP-8.

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Liquid crystalline naphthalene derivatives having different side chains were synthesized, and their liquid crystallinity and charge carrier transport properties were investigated. Those derivatives exhibited smectic mesophases in different temperature ranges, and their carrier transport in highly purified materials were basically ambipolar, and the carrier mobility ranges from 10-4cm2/Vs up to 0.1cm2/Vs, depending on the mesophases and the side chains.

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A novel amphiphilic compound possessing two semiperfluorinated alkyl chains and 2, 3-difluoro-1, 4-diphenylbenzene was prepared, and the physical properties were investigated using optical microscopy, differential scanning calorimetry and X-ray diffraction. The compound exhibited SmA and SmC phases. The SmA to SmC transition was not accompanied by a layer contraction.

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We have investigated the rheological behaviour and shear induced phase transition properties, especially focus on tilted and non-tilted smectic phases. We recorded the shear controlled birefringence by the spectrometer and polarizing microscope observation under shear simultaneously. It is quite evident that shear flow induces the Smectic C(SmC) to Smectic A (SmA) transition. It is completely contradicted the prediction from the simple understanding for SmA and SmC phase. (2) Smectic layers are well aligned by the shear both in SmA and SmC without any defects such as oily streaks. (3)Finally, C-director of the SmC is completely aligned along the flow and show the uniform birefringence without any defects such as Schlieren textures.

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We investigated physical properties of a rod-like molecule, 4-[4-(7-hydroxyheptyloxy)phenyl]- 1-(4-hexylphenyl)-2,3-difluorobenzene using polarized optical microscopy (POM), differential scanning calorimeter (DSC), and X-ray diffraction (XRD). The compound was found to exhibit nematic, smectic A, and smectic C phases. A smectic-like layer ordering was detected by XRD in the lower temperature range of the nematic phase. XRD and POM revealed that the smectic C phase consists of three different states, i.e., conventional SmC with a monolayered structure, SmC' possessing a weak bilayered character, and SmC'' possessing both monolayered and bilayered structures. Inter-layer interactions organized by hydrophobic-hydrophilic amphiphilicity and orthogonal-tilt amphiphilicity are discussed to explain appearance of the unusual liquid-crystalline phases with a hierarchical structure.

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We designed mesogenic compounds containing a cyclic unit and a rigid rod-like core, and investigated the physical properties using optical microscopy and differential scanning calorimetry. The compound possessing a cyanobiphenyl moiety exhibited a monotropic nematic phase. The appearance of the nematic phase for the compound is thought to be attributed to antiparallel interactions between cyanobiphenyl moieties. Addition of the compound possessing a phenylpyrimidine moiety to a host liquid crystal suppressed crystallization of the mixture without decreasing the liquid crystallinity.

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We studied the polarization-selective photoreaction and molecular reorientation in photocrosslinkable polymer liquid crystals (PPLCs). Influence of tolane moiety groups on the reorientational behavior in polymer liquid crystals was investigated.

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In this study, an acrylate monomer was mixed with 8BP(Cl)MB and photo polymerized in the cholesteric phase. The effect of the polymer stabilization of LC phase on the electric field induced transition was discussed.

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We added chiral dithienylethene derivatives into liquid crystalline (LC) conjugated polymers and prepared photoresponsive and induced chiral LC polymer. The chiral LC polymer showed a reversible change in chirality upon irradiations of UV and visible lights with an aid of annealing procedure. The photoresponsive behavior of the polymer was examined by measuring polarizing optical microscopy, UV-Vis spectra, PL spectra, circular dichroism spectra (CD), and circularly polarized fluorescence (CPF) spectra.

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In the present work, the spontaneous arrangements of the gold nanoparticles were accomplished with liquid-crystalline (LC) ligands. We assumed that the spatial arrangement and distribution of the metal nanoparticles could also be controlled using the photoresponsive LC ligands. In this study, we synthesized gold nanoparticles covered with a monolayer of the azobenzene LC ligands, and controlled the aggregation structures by solvents and light.

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The relationship between Photorefractive effect of cholesteric liquid crystals and the electrooptic properties was studied with a teo-beam coupling experiment. we report the unique properties which have been observed in the CLCs.

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Photorefractive effect of terthiophene polymer-stabilized FLCs was investigated.

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Liquid crystal (LC) lens with two divided and double circularly hole-patterned electrodes is developed for improving a range of a lens power with a negative lens property. The lens power of the negative lens property can be improved by assisting the applied voltage to the additional new hole-patterned electrode and two divided electrodes. The lens power of the LC lens with the double circularly hole-patterned electrodes is about three times as large as that of conventional LC lens with a single hole-patterned electrode.

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A thin film of insulator is introduced into a liquid crystal lens cell replacing the substrate between the patterned electrode and the liquid crystal layer. The distance between the electrodes then becomes so short that the driving voltages of approximate 3Vrms are realized, while the focus range is approximately 8(1/m).

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We have examined how the random lasing can be enhanced by adding gold nanoparticles to dye-doped liquid crystals. The plasmons with metal nanoparticles termed as localized surface plasmons (LSPs), can strongly scatter light of a specific wavelength, and generate intense near-field light in the vicinity of particle surfaces. Addition of metal nanoparticles to the dye-dope liquid crystals can lead larger scattering cross-section than that of dielectric nanoparticles and enhance the fluorescence of the dye resulting from the LSP resonance. With metal nanoparticles added, we have observed the random lasing properties induced by LSP resonance.

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We are developing a novel spectroscopic ellipsometer composed of two nematic hybrid cells in place of wave-plates. Setting the two LCRs at the appropriate angles and varying the applied voltage to each, we can control both transmittance optical axis and the magnitude of retardation independently. In this report, we show a prototype of the LC ellipsometer with using a tunable He-Ne laser and Ar laser as light source and the complex reflective ratios of Gold film on a glass substrate measured by our ellipsometer.

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Extremely thick polymer dispersed liquid crystal (PDLC) is investigated by using nematic liquid crystal 5CB and polymethyl methacrylate (PMMA) to attain millimeter-wave (MMW) and/or terahertz-wave (THz) LC control devices. Mixture of (5CB), MMA and benzoyl peroxide (BPO) is injected into the wedge-formed cell whose thickness changes from 0mm to 1mm, and is polymerized by heating the cell. Light scatting properties of the cell are measured by applying voltage and changing temperature. Morphology of PDLC is also observed by SEM.

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Liquid crystal (LC) phase shifters in the microwave and millimeter-wave region are investigated by using microstrip line (MSL) which is well known as an excellent planar type waveguide for the super high frequency electromagnetic waves. Novel wave guide structure, which can covert normal MSL to the inverted MSL structure, is designed to introduce LC materials on the MSL as CPW type LC phase shifters. Fundamental phase shifting properties up to 15GHz are demonstrated empirically by constructing the designed device structure.

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It is well-known that successive structual phase transitions appear in liquid crystals. In this presentation, it is studied how the structural phase transitions are influenced by the mixture of typical two types of liquid molecules, such as a stick type molecules and a disk one, and temperature.

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We study nucleation and growth of a lamellar phase from isotropic phase in lyotropic liquid crystals, aqueous solutions C10E3 and C12E5, focusing on their dependence on physical properties of the lamellar phase and quench depth. By being added hexanol and SDS, which decreases and increases the bending elastic modulus of the lamellar phase, the size of an onion nucleus at its formation decreased and increased, respectively. In addition, under similar quench depth, growth instability of the nucleus was promoted by adding hexanol, but suppressed by adding SDS.

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In the present study, we perform Monte Carlo simulation of a mixture of nematic liquid crystal and small amount of spherical molecules. We used hard spherocylinders and hard spheres for model molecules. Substrate is modeled by a large hard platelet. We discuss about affinity of homeotropic alignment due to the addition of spherical molecules.

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Viscoelastic properties of the interfacial layers formed between liquid crystal and a polymer sublayer were investigated using a quartz crystal microbalance (QCM). It has been reported that a solid-like interfacial layer can be formed between a polymer sublayer and a single-component liquid crystal. In the present study, the formation process of the interfacial layer was investigated for binary liquid crystal mixtures. In the first stage immediately after the liquid crystal was dropped on the polyimide, the thickness of the interfacial layer for a binary liquid crystal mixture was almost constant for hundreds of seconds. This induction period may suggest that the formation of the interfacial layer can be accompanied by a phase separation of the binary liquid crystal in the vicinity of the interfacial layer.

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