Chiral Liquid Crystal Polymers. 7. Structural Characterization of Thermotropic Polyesters Based on 4,4'-(terephthaioyldioxy)dibenzoic Acid and 1,3-butanediol

Abstract

A series of five samples of poly{(R)-1-methyl-1,3-propanediyl-[4,4'-(terephthaloyldioxy)]dibenzoate} obtained by polycondensation of 1,3-butanediol (enantiomeric excess comprised between 0 and 80%) with the diacyl chloride of 4,4'-(terephthaloyldioxy)dibenzoic acid were investigated by differential calorimetry, optical microscopy and X-ray diffraction. All the samples were semicrystalline and displayed a thermotropic smectic A phase followed by a cholesteric or nematic phase. The values of the transition temperatures T _S-N and T _i were not much affected by the enantiomeric excess of the flexible component, slight increases being detected with increasing chirality. There was evidence that the smectic A phase can assume a monolayer structure and/ or an interdigitated bilayer structure.

Keywords:

• chiral thermotropic polyesters
• poly(4,4'-terephthaloyldioxydibenzoate)s
• polymorphic liquid crystalline polymers
• enantiomeric excess
• bilayer smectic phase
• cholesteric phase.