In this paper, the authors demonstrate local alignment of nematic liquid crystal through the fabrication of a local micro-grating structure. The grating structure was fabricated through curing of the used material via a two-photon excitation laser-lithography process. A local twisted nematic cell was prepared using a rubbed substrate with the substrate with the micro-grating structure. The fabricated cell was observed under a polarizing microscope. The polarizing optical photographs suggest that liquid crystals molecules aligned parallel to the grating structure and local alignment is achieved in the grating region.

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We verify the validity of Fukudas model about the surface anchoring of liquid crystal at surface groove system through the observation of the existence of azimuthal nematic bistability in such a system. The bistability is achieved by a composite action between two orthogonal surface undulations, which tend to stabilize the nematic director along either of the two diagonal axes. The azimuthal easy directions of the bistability can be systematically controlled through modulating the pitch and the height of the undulations by nanoimprint lithography. This bistabililty may be considered as a new candidate for bistable display.

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We have proposed the multidomain patterning of the liquid crystal (LC) alignment by controlling the anchoring strength of alignment surfaces. The LC director distribution has been numerically and experimentally analyzed in the LC cell with one-dimensional periodic change of the anchoring strength. The twist angle distribution is strongly affected by the periodic size, as well as the anchoring strength, the cell thickness and elastic strain energies of K11, K22 and K33.

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In 1972 Berreman proposed a well-known theory on surface anchoring arising from the elastic distortions of a liquid crystal induced by a grooved surface. We argue that his theory is based on an invalid assumption and gives an incorrect result on the azimuthal angle (phi) dependence of the anchoring energy. The anchoring energy of a one-dimensionally grooved surface is proportional to sin⁴phi, in sharp contrast to the Berreman's energy proportional to sin²phi. Our result indicates that one-dimensional surface grooves cannot contribute to surface anchoring in the usual Rapini-Papoular sense.

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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 APA films on LC molecular orientation characteristic are examined.

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In our previous study, we critically reexamined Berreman's theory on surface anchoring to develop a correct theoretical treatment of the surface anchoring induced by a one-dimensionally grooved surface. Here we extend our theory to two-dimensionally patterned surfaces. We argue that a surface with a square pattern in contact with a "one-constant" nematic yields bistable anchoring whose easy axes are along the diagonal direction. This result is in remarkable contrast to the naive application of Berreman's theory to the same system, which result in no surface anchoring. We also discuss the anchoring of a hexagonally patterned surface.

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Liquid crystal (LC) alignment properties and the optical writing and erasing have been investigated in the LC cell with rubbed PVCi/PVA substrate. The writing is carried out by increasing the anchoring strength of PVCi. LC material dependence is found in the erasing process by exposing the excess UV light. The written image can not erase when using the LC which has no UV absorption around at 313nm of Hg lamp. The erasing can be possible when we add another LC having the UV absorption. The erasing capability disappears by adding the fluorescent dye into the LC. The dye is considered to work as the dissipation process of the UV light energy which changes the alignment surface of PVCi.

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New type of liquid crystalline copolymers comprising a photo-cross-linkable 4-oxycinnamic acid side groups and hydrogen bonding 4-oxybenzoic acid side groups were synthesized. Photoinduced reorientation behavior and generated birefringence of thin film using linearly polarized ultraviolet light are investigated.

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We have investigated photo-induced alignment of two different polyimides that contain azobenzene in the backbone structure; one was synthesized from pyromellitic dianhydride and 4,4'-diaminoazobenzene (PMDA-DAAB), and the other was made from oxydiphthalic anhydride and 4,4'-diaminoazobenzene (ODPA-DAAB). The in-plane anisotropy of the films induced by irradiation with linearly polarized light (LP-L) of wavelength 350-500 nm was determined from the polarization dependence of the absorption band assigned to the pi-pi* transition of azobenzene. From the LP-L exposure dependence of the in-plane anisotropy, we found that the photo-alignment efficiency of ODPA-DAAB is much higher than that of PMDA-ODA. By using ODPA-DAAB, the LP-L exposure is reduced to one-sixth of that required for PMDA-DAAB, to obtain the same in-plane anisotropy.

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As a non-rubbing liquid crystal (LC) alignment method, we have studied a low-energy ion-beam (IB) method using two kinds of ion species of Ar and N₂. Samples treated under various conditions of ion doses of ~10¹³ to ~10¹⁵ (ions/cm²) show almost comparable voltage holding ratio (VHR) to a rubbed sample. Although N₂ gives a lower light leakage than Ar, we find that light leakage at the dark state increases with increase in ion dosage for the both ion species. From these results, we show the usefulness of low-energy ion-beam alignment method for LCD production.

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We report the measurement of dielectric constants, birefringence, and pretilt angle in binary mixtures of nematic liquid crystals (CP7B and CCN-47). CP7B has a strong longitudinal dipole moment and exhibits a large positive dielectric anisotropy and CCN-47 has a strong transverse dipole moment and exhibits a large negative dielectric anisotropy. We show that the pretilt angle increases with dielectric anisotropy and birefringence much rapidly than reported earlier. It is suggested that this effect may arise due the presence of strong permanent dipole moments in the molecules.

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Anchoring energy at interface is usually derived as A_Qcos²q, i.e. Rapini-Papoular (RP) model taking account of the symmetry of the liquid crystal (LC) director in the bulk. However, for polar LC molecules, it is not true in the mono-molecular layer region from the interface due to the symmetry braking. Thus, it is straightforward to introduce the odd-rank term in addition to RP model as W(q)=-A_Pcos q- A_Qcos²q. It was shown that the second derivative of Taylor series at the energy minimum of W(q) yield the anchoring energy A_P²/4A_Q-A_Q.

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We report the first detailed electrooptical characterizations of the nematic (N) phase of a banana liquid crystal, and point out the difference from those of rodlike molecules. The pretilt angle is very small (less than 1 deg.) even in cells with a polyimide film yielding a high pretilt angle (about deg.) for calamitic molecules. We also measured the birefringence in the N phase as a function of temperature and estimated the orientational order parameter S. The molecule shows a small negative dielectric anisotropy in the N phase and the anisotropy becomes large in the B2 phase.

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An induction of electric polarization due to splay and bend deformations, called flexo-electric effects, is characteristic phenomenon in liquid crystals.[1] Stimulated by a recent investigation of large flexo-electric effect,[2] we have carried out the molecular dynamics study of the flexo-electric effect. A system studied here is the one composed of Gay-Berne particles, where the particle is of banana shaped, consisting of two same Gay-Berne particles combined together with fixed bend angle. The simulation boxes are prepared; fan-shaped column with homogeneous anchoring condition at the curved surfaces. In these systems, the bend deformation induces the nematic order parallel to the curved surface; , with a radial unit vector er and radius R. In order to obtain such ordering topology, we apply a magnetic field in the axial direction where negative anisotropy of susceptibility is assumed. The polarization Pd is proportional to the biaxial order whose temperature dependence is shown.

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Heat capacity measurements have been carried out on mixtures of banana- and rod-shaped molecules with a high-resolution ac calorimetry as well as non-adiabatic scanning calorimetry. Significant anomalies have been observed at the B4-B4' phase transition, while small anomalies were also observed at the B4'-Bx phase transitions.

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We have studied various ferroelectric liquid crystals by conoscopy using tilted cells to find the quadrupolar ordering of the shortest molecular axis in the perfectly unwound state. Some materials exhibit increasing biaxiality, while others shows decreasing biaxiality with rising temperature. A temperature-induced sign reversal of biaxiality is observed in the former. Three different physical mechanisms are: (i) anisotropic fluctuations of the long molecular axis, (ii) a biased rotational quadrupolar ordering around the long axis, and (iii) the local field effect. By means of a simple theoretical investigation, we conclude that these two types of trends are due mainly to the opposite sign of the biaxial order parameter $C$, which represents the mechanism (ii), i.e.\ the quadrupolar ordering.

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Electric field induced SmC*alpha-SmC transition is studied on the basis of a concept of discrete soliton. The wave number of periodic structure corresponds to the soliton density, whose dependence on the electric field is shown to make a devil's staircase. An excitation of soliton just below the critical field is quite drastic showing that repulsive interaction between discrete soliton is quite short range.

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The experiments were conducted on Langmuir monolayers composed of chiral dipalmitoyl-phosphatidylcoline (D-DPPC and L-DPPC) molecules and racemic DPPC (DL-DPPC) molecules using the Maxwell displacement current (MDC) and the Brewster angle microscopy (BAM) to examine orientational structures and domain shapes of monolayers. Chiral DPPC monolayer domain shapes were formed without mirror symmetry, which had a close relation to chirality of molecules. Racemic DPPC monolayer domain shapes were spanner-like, which had the two lobes bent towards opposite directions singly in a domain with mirror symmetry. These shapes indicate phase seperation ocurrs within the domain.

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We have observed spanner-shaped domains from racemic DPPC monolayers by Maxwell displacement current and Brewster angle microscopy. We have constructed an electrostatic model of racemic lipid domains, and analyzed the possibilities of chiral phase separation within a domain. It was found that the diffusion equilibrium condition is written as the analogous form to the diffusion equilibrium condition of Bragg-Williams theory.

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Phase behavior of a liquid crystalline oligomer composed of a semifluorinated alkyl chain and three cyanobiphenyl mesogenic chains was investigated under pressures up to 100 MPa using a polarizing optical microscope equipped with a high-pressure optical cell and high-pressure DTA apparatus. The T-P phase diagram was determined for both the cooled and annealed samples, in order to estimate both the stable and metastable cubic phases under pressures up to 100 MPa.

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Two cubic (Cub)-phase forming compounds, 4'-n-hexadecyloxy-3'-cyanobiphenyl-4- carboxylic acid (ACBC-16) and its 3'-nitro analogue (ANBC-16) were studied by infrared spectroscopy (IR) and quantum chemical calculation (QCC). The only difference between the two compounds is the lateral substituent at the 3' position of the biphenyl ring, which gives rise to differences in the smectic C (SmC) layer thickness and the temperature interval of the Cub phase between ACBC-16 and ANBC-16. Close inspection of IR and QCC results and comparison of the temperature behaviors of the two compounds reveal that steric effect of NO2 group that is slightly bulkier than CN group is an origin for those differences. The molecular stackings in the crystalline, SmC, and Cub phases of those compounds are discussed.

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Thermotropic cubic mesogens BABH-n exhibit two types of bicontinuous cubic phases with Ia3d and Im3m symmetries, depending on temperature and the alkyl chain length. We have examined their structures by using small-angle X-ray scattering and infrared spectroscopy. Especially, in this presentation, we focus attention on the packing structure of the Ia3d-type cubic phase at the molecular level, and discuss some differences observed between the short- and long- chain systems.

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BABH-n is a molecule which has a rigid core and flexible chains on both ends. Depending on the length of the alkyl chains, BABH-n shows two symmetrically different cubic phases (Ia3d-Cub, Im3m-Cub). In these phases, the number of diffractions of small-angle X-ray scattering (SAXS) is about ten due to highly disordered nature of the phases. Therefore, a conventional Fourier synthesis brings large truncation errors to the electron density maps. To avoid the disadvantage, we adopted the so-called maximum entropy method (MEM) to the data. From the resultant density maps, we discussed the appropriate internal structures of the cubic phases.

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Thermotropic cubic mesogens BABH-n exhibit two bicontinuous cubic phases with Ia3d and Im3m symmetries, depending on the alkyl chain length and temperature. The Im3m cubic phase is observed only in thermotropic LC systems and the phase transition to and from the Ia3d cubic phase is of much interest. So we studied the mechanism of cubic-cubic phase transition, using the time-resolved small-angle X-ray scattering.

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For the development of organic-inorganic hybrid liquid crystals (LCs), we have prepared monodispersed iron oxide magnetic nanodisks with different sizes. The synthesis of the spinel-type iron oxide nanodisks was carried out by the decomposition of dioctyl ether solution of Fe(CO)5 in the presence of m-chloroperoxybenzoic acid (mCPBA) and tridecanoic acid or an LC with carboxylic acid moiety. The thermal behavior and the self-assembled structure of the resulting organic-inorganic hybrid materials were identified by POM, DSC, SAXS, and TEM. The hybridization techniques would lead to the development of novel and dynamically functional materials multi-responsive to magnetic and electric fields.

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A novel organic-inorganic hybrid thermotropic liquid crystal with thermotropic cubic mesophases is developed by the hybridization of organic dendrons having an amino-group with CO2H-modified spherical gold nanoparticles with narrow size distribution through ionic interaction or formation of covalent bonding. Small angle X-ray scattering and DSC measurements reveal that the hybrids show thermotropic cubic mesophases in a wide range of temperatures. Effect of the generation of the dendrons, the particle size, and the monodispersity on the formation of the thermotropic mesophases has been examined. This technique would lead to the development of novel and dynamically functional materials with light insulating-transmitting property.

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Triphenyl phosphine oxide derivatives assemble into columns via a weak phi-phi interaction. They should be a new building block of phi-conjugated liquid crystals. We have designed and synthesized novel liquid crystals based on phosphine oxide with phi-conjugated moieties. The molecules show thermally stable columnar phases. We have examined the liquid-crystalline and photophysical properties to determine the assembled structures of the phi-conjugated moieties.

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Intermolecular ferromagnetic interactions (J > 0) in all-organic magnetic materials were observed only in the solid state at low temperatures. Here we show the first observation of unique intermolecular mesoscopical-ferromagnetic interactions only in the liquid crystalline (LC) state of all-organic radical compound 1 which contains a polar and chiral cyclic-nitroxide unit in the mesogen core and shows an achiral or a chiral nematic (N or N^*) phase at higher temperatures. The LC grains on water were attracted by a weak permanent magnet, whereas the crystalline phases were almost paramagnetic and not responsive to the magnet. We observed that the motion of the LC grains was faster in the N^* phase than in the N phase.

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Although metallomesogens with redox-activity have already been reported in the past, the reports on the redox properties concern only their solution state, where no LC structures exist. This drawback has then restricted the understanding of the direct correlation between the LC structures and redox functionality. Here, we demonstrate a strategy that appears particularly well suited for the design of redox-active LC materials. A significant stabilization of the Colho phase is bringing out by the interplay of the branched alkyl chains and the stacking interactions of the central planar core comprised of the asymmetric mixed-ligands. The result reported here also constitutes the first unequivocal evidence of electrochemically induced a LC-to-ionic liquid phase transformation at rt.

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In this work, novel bis{bis[4-(3,4-dialkoxy)phenoxy]phenylglyoximato}nickel(II) have been synthesized in order to develop the materials that visualize van der Waals forces in very wide temperature region. These present novel complexes exhibit thermochromism changing their colour with temperature. The peripheral long alkoxy chains fasten the central metals. This originates the present thermochromism. It is noteworthy that these materials show the highest apparent pressure and the widest temperature region in the bis(glyoximato)nickel(II) complexes known to date.

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It is well-known that pthalocyanine Si complexes form polymers and oligomers via axial ligands to give a short-range columnar structure where p-electronic systems stack to each. In this work, the monomer, dimers and oligomers were syntheised to investigate the mesomorphic properties.

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New ionic liquid crystalline systems composed of carboxylate and ammonium derivatives were synthesized by ion complexation. The ionic liquid crystalline systems without aromatic mesogenic groups formed liquid crystalline phases such as smectic A, hexagonal columnar, and cubic mesophases. At the smectic A-cubic phase transition, dark domains, which exhibited the formation of an optical-isotropic phase, appeared and grew slowly in a focal conic fan texture of the smectic A phase. The X-ray diffraction pattern of the cubic mesophase exhibited the existence of d(200), d(210), d(211), d(310), and d(430), which indicated the formation of Pm3n.

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We reported a novel ionic liquid crystal oligomer, sodium 1, 2-bis{6-[4-(4-cyanophenyl)phenyloxy]hexyloxycarbonyl}ethane sulfonate (SBCPHS), in which sodium sulfonate is introduced to the U-shaped dimeric system. The compound exhibited two rectangular columnar phases, i.e. Colrd (C2/m) and Colrd (P2/m). The phase behavior results from competition among a space filling effect, intermolecular interaction between cyanobiphenyl moieties, and micro-segregation between ionic and hydrophobic groups. In this work, we studied lyotropic systems of SBCPHS / Water and SBCPHS / 6OCB. In addition to a typical lamellar phase, we found an interesting molecular organization with myelin figures.

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2, 3, 6, 7, 10, 11-hexakis (4-alkyloxy-2, 3, 5, 6-tetrafluorobenzoyloxy) triphenylenes (CnF4; n=12, 14, 16) and the branched chain derivative [C7(1C1)F4] were synthesized to study the mesomorphic transition behavior by polarized optical microscope, DSC and XRD techniques. It was found that CnF4s exhibit Colh phase having a wide range of temperature, and as the peripheral chains are elongated, the clearing points get slightly lowered. It was shown that the elongation of the peripheral chains and the introduction of branched structure into the chains give no change in the type of mesomorphism, implying a strong attractive interaction among the fluorinated phenyl groups.

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Sandwich type of tris, bis[octakis(3,4-dialkoxyphenoxy)phahtlaocyaninato]lutetium(III)complexes (abbreviated as triple-deckers and double-deckers) were synthesized. Their mesomorphic properties were investigated by using polarization microscope, DSC and temperature-dependent X-ray diffraction techniques. Double-deckers(n=10-16) and triple-deckers(n=9-16) showed a Coltet phase. Moreover, they exhibit spontaneous perfect homeotropic alignment in the Coltet phase. It takes 9 hours for the double-deckers, only one minute for the triple-deckers to achieve the perfect homeotropic alignment.

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In this study, the alignment change of liquid crystal domains induced by infrared irradiation was investigated for helical columnar mesophases (H) of hexahexylthiotriphenylene (C6STP). A uniform and anisotropic alignment change of domains was observed when a polarized infrared light corresponding to the wavelength of the aromatic C-C stretching absorption band of triphenylene core was irradiated. The results strongly imply that the infrared irradiation is a possible technique for device fabrication by use of columnar mesophases as an organic semiconductor.

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With the recent progress of liquid crystal display technology, requirements for characteristics, especially for the quick response property, of liquid crystal materials are increasing. To achieve quicker response, development of a polar nematic liquid crystal compound with higher nematic-isotropic transition temperature and higher anisotropy is required. We have designed and synthesized compounds with five rings framework with -CF₂O- linkage group. These compounds have high nematic-isotropic transition temperature, high dielectric anisotropy and high optical anisotropy. Moreover, these compounds have better solubility than conventional five rings compounds and chemical and physical stability. These compounds are suitable for various kinds of purposes and conditions with wide variety of TFT-LCD driving modes.

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Recently, we reported that the solubility of gases and solids in nematic liquid crystal solvent was calculated by use of regular solution theory. In this report, we investigate the solubility of water in nematic liquid crystal solvent. As a result, it is found that the solubility of water is also explained by the solubility parameter difference between a solute and a nematic liquid crystal solvent.

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It is known that cholesteric liquid crystal can be induced by adding a small amount of chiral dopant to a nematic liquid crystal. We found that chiral dopants having 1-(1-naphthyl)ethylimine as an optically active moiety showed large helical twisting power for nematic liquid crystal, 6-OCB. In the case of the chiral dopant showing largest helical twisting power, it can be induced helical pitch comparable to the visible light wavelength by mixing only 4wt%.

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We prepared a series of homologues of novel binaphthyl derivatives, and investigated their induced helical senses and pitches in different host nematic liquid crystals. In the mixture with 5-hepthyl-2-(4-hexyloxyphenyl)primidine, temperature-dependent helical twist inversion was observed for the mixture doped with the odd members, whereas a right-handed helix was observed for the mixture doped with the even members. On the other hand, a left-handed helix was induced in each mixture with 4-methyloxyphenyl 4-pentylcyclohexane. We discuss the change in sign of the induced pitch in terms of chirality transfer from the binaphtyl derivative to a host nematic liquid crystal.

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New atropisomeric chiral dopants were synthesized from an optically active trans-1,2-cyclohexanedicarboxylic acid derivatives and achiral biphenols. It was found that the control of the axial chirality was useful for increasing the helical twisting power (HTP) values. On the other hand, the HTP values of the chiral dopants were strongly depended on the terminal substituents. The chiral dopant having a fluoro terminal substituent showed the largest HTP value.

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We synthesized the symmetrical achiral dimmer, a,w-bis(4-(4'-butoxy- phenyl)benzylthio)octafluorobutane with fluorocarbon on center, connected via sulfur and with two butoxybiphenyl on the end and (4-(4'-butoxyphenyl)benzylthio)octafluorobutyliodide. Their mesogenicity was studied by DSC measurements and POM observations. The X-ray diffraction study revealed the relationship between the molecular shape and mesomorphic structure.

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We have found that a polymerization of an optically active phenyl isocyanide bearing an L-alanine pendant with a long alkyl chain by a ethynediyl Pt-Pd complex as an initiator produced the diastereomeric helical polymers consisting of right- or left-handed helix with different molecular weight to each other, which can be further separated into the diastereomeric helices. Furthermore, It was elucidated that these polymers form smectic A liquid crystals in the concentrated solutions.

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This paper describes that synthesis and mesomorphic properties of 2-oxo-2H-chromen-6-yl 4-alkoxycinnamates (compounds 1-n). Compounds 1-n show smectic A (SmA) phase exclusively, and the thermal stability increase on ascending the homologues. The layer spacings of the SmA phase were characterized by means of a small angle X-ray diffaction study and the results are compared with the molecular length. These results suggest that the SmA phase has a partially bilayer structure, where the 2-oxo-2H-chromene moiety arranges side by side around the layer boundary.

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Synthesis of poly(a-fluoromethylacrylate)s with biphenyl mesogenic groups were performed using anionic polymerization. We obtained the polymers with number average molecular weights of ca. 100000. The physical properties of polymers were studied by thermal, optical and spectroscopic methods. The effects of CF3 groups on the structure and mesomorphic phase transition were studied.

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A clear liquid crystalline phase has been discovered in a polyolefin of poly(methylene-1,3-cyclopentane) (PMCP) obtained with cyclization polymerization of 1,5-hexadiene (HD) using a zirconocene catalyst in the presence of chain transfer reagents. PMCP clearly shows fluidity and birefringence above the glass transition temperature under the ambient conditions. Schlieren-like texture indicates nematic liquid crystalline phase. Clear diffraction pattern is observed in wide-angle X-ray diffraction analysis below the isotropization temperature (Ti). The Ti decreases with decreasing of molecular weight the PMCP. Non-Newtonian viscosity region in the range of low share rate, which is a characteristic of liquid crystal, has been detected below the isotropization temperature.

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We prepared a homologous series of novel non-symmetric dimeric liquid crystals in which a 2,3-difluoro-1,4-diphenylbenzene unit and a 4-(4-fluorophenyl)benzene unit are connected via a flexible spacer, and investigated their physical properties. All compounds exhibited enatiotropic nematic phases. When an electric AC field was applied, a striped pattern that was similar to Williams domain appeared in the nematic phases of these compounds, whereas such a pattern was not observed in a nematic phase of an equimolar mixture of the corresponding monomeric compounds. We discuss structure-property correlation of the polar liquid crystal oligomers.

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The electric field induced change in chiral nematic phase (N* phase) was investigated.

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We prepared a homologous series of novel liquid crystal trimers, 1,4-bis{4-{omega-[4-(5-dodecylpyrimidine-2-yl)phenyloxy]alkyloxyphenyl}carbonyloxy}benzene I-(m,n) and investigated their physical properties using optical microscopy, differential scanning calorimetry and X-ray diffraction. All compounds exhibited enantiotropic nematic (N) and smectic C phases. Pronounced odd-even effects were apparent for the transition properties on varing the spacer length. X-ray diffraction measurements suggest that the SmC has a monolayer structure in which the molecular long axis is tilted to the layer normal. Furthermore, formation of defect-lines was observed for the SmC phases.

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