Contents

Abstructs of Reviews

Outline of the Development of Nematic Liquid Crystal Compounds for LCD

Takashi INUKAI / Kazutoshi MIYAZAWA

Abstract : Discovery and early period of liquid crystal research are briefly reviewed, and representative nematic liquid crystal compounds used for the dynamic scattering and twisted nematic displays is also outlined. Description on the developments of compounds aimed at application for newer display modes are given.
Keywords : Review, Nematic liquid crystals, Applicability

Trend of Development of Liquid Crystal Displays

Masataka MATSUURA

Abstract : The recent development of Liquid Crystal Displays (LCDs) makes remarkable progress. Monochrome and/or color LCDs for OA uses such as word processor, personal computer, work station, and color LCDs for AV uses such as personal TV, car navigation, wall hanging TV, projection TV are being commercialized as a substitution of CRT. In this paper, the author reviews the recent developments of LCDs which aims at high performance LCDs. The recent developments of transparent color LCDs such as wide viewing angle, large size, high resolution will be described, as the vigorous development is being done, aiming at realization of the same level of display performance as CRT. The development of color reflective LCDs for new personal digital assistant will also be described.
Keywords : Liquid crystal display, Direct matrix addressing LCD, Active matrix addressing LCD, Wide viewing angle of TFT-LCD, Reflective color LCD

Photoconductive Liquid Crystals„ŸA New Class of Organic Electronic Materials

Jun-ichi HANNA

Abstract : This article describes electrical properties of photoconductive liquid crystals including discotic and calamitic ones which have been discovered recently, reviewing those of conventional organic photoconductors such as molecularly doped polymers and amorphous thin films of photoconductive molecules. ln addition, the potentials of these materials as a new class of organic electronic materials are discussed on the basis of our recent results on the electrical properties of these materials and in comparison with the conventional photoconductors, giving a special stress to practical application for electronic devices.
Keywords : Photoconductive liquid crystals, Electronic material, Photoconductivity, Carrier transport

Coating Film of Discotic Nematic Mesophase and its Application to Optical Material

Ken KAWATA / Masayuki NEGORO / Hideyuki NISHIKAWA / Masaki OKAZAKI

Abstract : Novel technique of optical compensation film utilizing an optically negative birefringence and inclined optic axis in the hybrid manner of triphenylene discotic liquid crystals is described. Discotic nematic (ND) phase is quite suitable for this purpose because of low viscosity in order to realise uniform orientation without any defects over broad area. But few discotics show ND phase. therefore we have studied the relationship between molecular structures of triphenylene discotic liquid crystals and the factors for the formation of ND phase in view of steric effects and intermolecular interactions. Electrostatic or dipole-dipole interactions and van der Waals force are rather strong based on polarity of hetero atoms composing side chains. These interactions influence multifold to neighboring molecures because of structural characteristics of discotics bearing several side chains. Therefore, the total force of interactions often deviate from proper molecular interaction range of forming ND phase. As a result, we suppose the possibility of forming ND phase would be small. We have also investigated the orientational behavior of their coating films with free surface on the alignment layer, and found them aligning in a single direction and in a hybrid way when heating to the temperature forming ND phase within the range of some microns thick. We have succeeded the fixation of such a novel orientation of ND phase by using new triphenylene benzoates bearing photo-polymerizing groups at the end of side chains. The combination technique of those films has produced optical compensation ability in TN-LCDs and proved to be effective of widening their viewing angle.
Keyword: Discotic nematic phase, Hybrid alignment, Photo-polymerization, Optical compensation film

Making Well-oriented Liquid Crystalline Sol of Filamentous Assemblies of Proteins

Ichiro YAMASHITA / Keiichi, NAMBA

Abstract : Bacterial flagellar filaments can adopt distinct polymorphic forms including two straight forms, in response to changes in the environment. Chemically identical subunits construct super-coiled filaments by bonding to each other in a regular manner. To understand the mechanism of the polymorphism and self-assembly, we have been studying the structures of straight flagellar filaments, using X-ray fiber diffraction. The X-ray fiber diffraction method is potentially powerful in studying filament structures at high resolution. However, this method requires very well-oriented liquid crystalline filament sols. We have studied the method of orientation and we have found that following four points are important.
1. Relatively small aspect-ratio (flagellar-length/diameter).
2. Introduction of a small repulsive force to prevent aggregation.
3. Centrifugation of filament sol to achieve orientation and high concentration.
4. Use of a strong magnetic field to orient domains of flagellar filaments sol.
The pH and the salt condition are the major factors in the second requirement and this procedure produces nematic liquid-crystalline domains in the sol. When the liquid-crystalline sols are centrifuged, the centrifugal force orients the filaments parallel to the force and concentrates filaments, and sols turn into more concentrated and more oriented liquid crystals. Then, we use a super-conducting magnet system which produces a central field of 13.5 Tesla to further improve the orientation. By these procedures, the flagellar filament sols have been oriented reproducibly to the disorientation angles as small as 0.6 degree. This preparation method is in principle and universally applicable to other systems. It was used to make well-oriented TMV and F-actin sols and X-ray diffraction patterns from those liquid crystalline sols showed well-separated layer lines.
Keyword : Bacterial flagellar filament, X-ray fiber diffraction, Lyotropic liquid crystal, Well-oriented filament sol