Susumu Era

New Room-Temperature Ferroelectric Liquid Crystals : Material Constants and Electro-Optic Properties

A binary ferroelectric liquid-crystal mixture having both room-temperature ferroelectricity and a large spontaneous polarization has been developed. The temperature range is from 20°C to 34°C. The spontaneous polarization is almost the same value, 4 nC/cm2, as that in DOBAMBC. Five material constants for the mixture; the transition temperature, spontaneous polarization, helical pitch, tilt angle and birefringence, are reported. A guest-host-type device was fabricated using the mixture, and some potential problems in the application of the materials to electro-optical switching devices are pointed out on the basis of the optical properties of this device.

Synthesis and physical properties of alkoxymethylene substituted phenyl cyclohexanecarboxylates

Abstract The homologous series of 4-alkoxymethylene-substituted-phenyl 4′-alkylcyclohexanecarboxylates are prepared. And their transition temperatures, bulk viscosities and birefringences have been measured comparing with the series of 4-alkoxy-substituted-phenyl 4′-alkylcyclohexanecarboxylates. The differences between the alkoxymethylene-substituted series and alkoxy-substituted series are discussed. Alkoxymethylene groups contribute to lowering the transition temperatures, and also reducing the bulk viscosities and optical anisotropy compared to the alkoxy groups as terminal groups of mesogens. This is apparently due to the higher flexibility of the alkoxymethylene groups, which affected the packing of molecules.

Study of New Liquid Crystal Materials (II): Synthesis and Mesomorphic Properties of Alkoxymethylene Substituted Phenyl Cyclohexanecarboxylates

Abstract The properties of alkoxymethylene-substituted-phenyl alkylcyclohexanecarboxylates are described. Such phenyl cyclohexanecarboxylates exhibit either a monotropic or an enantiotropic nematic phase. Their clearing points were lower than those of alkoxy-substituted-phenyl alkylcyclohexanecarboxylates, an effect considered to be due to the flexibility of the alkoxymethylene groups.

Dynamical Aspects of Switching between Surface Stabilized States in Smectic C* Ferroelectric Liquid Crystal

The switching process in a surface stabilized ferroelectric liquid crystal (SSFLC) cell under triangular wave voltage is studied by taking stroboscopic micrographs. Interior ±2π disclination motions and surface layer changes with surface disclinations are observed even in a uniform-state favored cell. The asymmetric semicircular shape of the ±2π disclination loop is observed under low frequency triangular waves of 0. 1 Hz. The loop becomes elongated hexagonal, when the frequency increases to 1 Hz or 10 Hz.

Helicoidal Structure and Spontaneous Polarization in the Mixtures of Ferroelectric Liquid Crystal with Its Racemate

Some phenomena that critically depend on the helicoidal pitch and spontaneous polarization in ferroelectric liquid crystals are studied. These quantities are changed by mixing active DOBAMBC with its racemate. The phenomena investigated are: (1) Directions of the spontaneous polarization at the bounding surfaces, (2) Critical thickness for realizing bistability, (3) Two types of fringe patterns corresponding to the helicoidal pitch, (4) Disclination lines in the middle of a cell, (5) Unwinding of the helicoidal structure induced by an electric field, and (6) Winding of the helicoidal structure near the phase transition to Sm A.