Frustrated smectic liquid crystalline phases in lactic acid derivatives

Abstract

ABSTRACTWe have prepared and studied a series of compounds with different types of molecular core and lactate unit in the chiral terminal chain. We draw a survey and comparison of their mesomorphic properties with respect to the occurrence of twist grain boundary (TGB) phases. The materials exhibit extremely wide TGBA phase more than 60K broad, unique TGBA-TGBC-SmC*-SmCA* phase sequence and unique re-entrant TGBA phase below the SmA phase. TGB phases have been induced in binary mixtures of molecules with different molecular shape and chirality (chiral lactic acid derivative and non-chiral hockey-stick mesogen). Unique effect is observed for compounds with TGBA phase, where the applied electric field transforms the planar texture into the homeotropic one, homogeneously dark in crossed polarizers. The process is analogy of the Frederiks transition so far known only for nematics. This effect, changing the bright state to the dark one, is promising for applications.