Preliminary communication Thermotropic liquid crystals of polyesters having a mesogenic p,p' -bibenzoate unit X. Distinct orientation of molecules in a thin SmCA film stretched from isotropic melt, providing evidence for the biaxiallity of the SmCA p

Abstract

A thin oriented SmC film of a main-chain polyester was prepared by drawing from the A isotropic melt, and X-ray patterns were observed by irradiation from three characteristic positions relative to the film. The results clarify the biaxiallity of the SmC phase, with a A distinct molecular orientation where the mesogenic groups are tilted in a zigzag manner in a direction perpendicular to the film surface. Such a biaxial orientation is considered to result from the relaxation from the extended arrangement of the mesogenic groups on stretching to the stable zigzag arrangement.