Study on the choresteric-smectic isothermal phase transition inducedby application of electric field

合成了一系列以三环结构为介生单元的胆甾液晶。当电场作用于LC时，液晶表现出从平面相到焦锥相的等温相变。焦锥相位表现为电光开关。电光开关的响应时间约为600 μ s，焦锥相位的自发极化为5nC/cm^2。结果表明，焦锥相为铁电相。由此可见，本研究合成的胆甾相LC呈现出由胆甾相向铁电相的等温相变。胆甾型LC在电场作用下表现出三态电光开关。

A series of cholesteric liquid crystals possessing three ring structure as a mesogenic unit was synthesized. The liquid crystal exhibited an isothermal phase transition from planer phase to focal conic phase when an electric field was applied to the LC. The focal conic phase showed electro optical switching. The response time of the electro optical switching was about 600 micro s. The focal conic phase exhibited a spontaneous polarization of 5nC/cm^2. Those results indicate that the focal conic phase was a ferroelectric phase. Thus, It was shown that the cholesteric LC synthesized in this study exhibits isothermal phase transition from cholesteric phase to ferroelectric phase. The cholesteric LC shows three-states electro optical switching under application of electric field.