Spacer length dependence of mesomorphic characteristics and bistable electro-optical effects for smectic (liquid crystalline copolymer/liquid crystals) composite systems

Mesomorphic characteristics and bistable electro-optical switching effects of smectic composite systems composed of side chain liquid crystalline copo lymer (LCcoP) with a weak polar methoxy terminal group in a side chain and low molecular weight nematic liquid crystals (nematic LCs) with each strong polar cyano end group have been investigated. The spacer length of the mes ogenic side chain in LCcoP has strongly affected the mesomorphic characteri stics and the electro-optical effects of the (LCcoP/LCs) composite systems. The response speed of the binary composite systems became faster with a de crease of the spacer length. The binary composite systems showed reversible and bistable electro-optical switching characteristics with response time of similar to 100 ms, that is, a light scattering state and a transparent o ne upon the application of ac electric fields with low frequency (up to - H z) and high one (10-10(5) Hz), respectively. However, a light scattering st ate was also observed due to the sign reversal of dielectric anisotropy upo n the application of an ac electric field above -10(5) Hz.