Rigid-rod liquid crystalline polyesters based on n-alkoxyterephthalic acid and 4,4′-dihydroxybiphenyl

The synthesis and the characterization of a set of polymers obtained by polycondensation of n-alkoxyterephthalic acid(n = 1, 3, 5, 7)and 4,4'-dihydroxybiphenyl are reported. The n-alkoxy insertion promotes the processability of the material by lowering the melting temperature. All polymers show the nematic phase at about 300 degrees C, almost independently of the length of lateral substituent. The isotropization is not observed up to 450 degrees C, where thermal decomposition occurs. The temperature of glass transition decreases with increasing it, ranging from 170 degrees C (n = 5) to 220 degrees C (n = 1). (C) 1998 John Wiley & Sons, Inc.