TGB A* state in a homologous series of diarylethane α-chloroester ferroelectric liquid crystals

Abstract

A twist grain boundary (TGB A*) or twisted smectic A* state was observed in two compounds of a homologous series of diarylethane α-chloroester ferroelectric liquid crystals. The phases have been characterized by optical polarizing microscopy and differential scanning calorimetry. Textures of the TGB A* state obtained by preparation on a glass slide and in thin homeotropically orienting liquid crystal cells or as free-standing films clearly show the helical structure, whereas preparation in homogeneously orienting LC cells suggests that the helical structure is suppressed by the cell geometry, in a similar way to that observed for S*C phases in the surface stabilized geometry (SSFLCs).