Ion-conducting behaviour and photoinduced ionic-conductivity switching of composite films containing crowned cholesteric liquid crystals

Abstract

Ionic conduction has been studied with composite films of polyester elastomer, alkali-metal perchlorate and cholesterol derivatives incorporating a benzocrown moiety (crowned cholesterols), which can form a cholesteric liquid crystal when mixed in the appropriate molar ratio at the measuring temperatures of ionic conductivity. In films with lithium or sodium salts, the activation energy for ionic conduction was lower under the liquid-crystal conditions than under the corresponding isotropic conditions, implying specific ionic conduction in the cholesteric liquid-crystal phase. In the ion-conducting composite films that also contained a small amount of crowned cholesterol carrying the azobenzene moiety, significant photoinduced ionic-conductivity switching, based on the order–disorder cycle of the liquid-crystal state, was realized by alternate irradiation with UV and VIS light.