Fast bistable switching composite systems of side-chain liquid-crystalline copolymer and low molecular weight liquid crystals

Mesomorphic characteristics and bistable light switching properties of the composite system composed of various side chain type liquid crystalline copolymers (LCcoPs) which includes the flexible dimethylsiloxane segment as one constituent of the copolymer and low molecular weight nematic liquid crystals (nematic LCs) have been investigated in order to construct the optimum smectic binary composite system with both fast light switching characteristics and stable memory effects at room temperature. Two types of novel (LCcoP/nematic LCs) composite systems in a smectic phase studied were (1) (pseudo LCcoP with weak polar methoxy terminal groups/nematic LCs with strong polar cyano terminal groups) and (2) (smectic LCcoP with strong polar cyano terminal groups/nematic LCs with the same terminal groups). The response speed of bistable light switching for the binary composite system could be remarkably improved by reducing the LCcoP fraction maintaining a smectic state at room temperature due to an increase of the optimum flexible segment fraction.