Self-assembly, mesomorphic behavior, and ionic conductivity of polymerized ionic liquid crystals with a threshold switching characteristic

摘要

A series of pyridinium-based polymerized ionic liquid crystals (PILCs) with different anions were synthesized, including poly(pyridinium bromide)s and poly(pyridinium trifluoroacetate) s, and their chemical structure, liquid-crystalline properties and conductivity properties were investigated by many experimental techniques. At low temperature, some PILCs containing less cholesteryl mesogens presented smectic A phases; while the PILCs containing more cholesteryl mesogens displayed bicontinuous cubic phases. At high temperature, all the PILCs showed nematic phases. Compared with the corresponding poly(pyridinium bromide)s based on identical polymer cations, the poly(pyridinium trifluoroacetate)s showed lower glass transition and isotropic transition temperature. The PILCs displayed excellent temperature-dependent ionic conductivity, making it attractive for applications in temperature-controlled electronic switches. In cubic and smectic A phases, the PILCs presented Arrheniuslike ionic conductivity behavior, and they exhibited Vogel-Fulcher-Tammann-like behavior in nematic phases.