Liquid crystal polymers. 14. Synthesis and properties of thermotropic poly(1,4-alkylphenylene terephthalates)

A series of terephthalate polyesters was prepared from substituted hydroquinone monomers that contained a single cyclic or branched alkyl group. All the polymers were crystalline with melting points well below 400°C that decreased as the size of the cycloalkyl substituent increased. Most of the polymers had clearing temperatures below 400°C and all formed nematic melts. Copolyesters that contained equimolar amounts of two different substituted hydroquinone monomers, which were crystalline and had broad temperature ranges for nematic phase formation, were also prepared.