THERMOTROPIC POLYESTERS - SYNTHESIS AND PROPERTIES OF T-BUTYL-SUBSTITUTED POLY(4-OXYBENZOATE)S

Two series of novel t-butyl-substituted copolyesters, poly(3-t-butyl-4 -oxybenzoate-co-4-oxybenzoate)s and y(3,5-di-t-butyl-4-oxybenzoate-co- 4-oxybenzoate)s, have been synthesized. The former were prepared by th e conventional transesterification reaction via an acetolysis route an d the latter were made from or via a novel monomer, 3,5-di-t-butyl-4-h ydroxybenzoyl chloride. These polymers were characterized by solution viscometry, infra-red spectroscopy, wide angle X-ray scattering, hot-s tage polarizing microscopy and thermal analysis (d.s.c., t.g.a. and t. m.a.). Both poly(3-t-butyl-4-oxybenzoate) and poly(3,5-di-t-butyl-4-ox ybenzoate) were semicrystalline and did not melt before decomposing, a lthough they were easily soluble in conventional solvents. Of the mono substituted copolymers, only the 50:50 composition melted at a tempera ture substantially below decomposition, forming a nematic mesophase, w hich makes this copolymer the most promising for processing. None of t he disubstituted copolymers melted below its decomposition temperature .