THERMOTROPIC AROMATIC COPOLYESTERS OF CATECHOL

Three new series of thermotropic aromatic main-chain polymers were synthesized and studied by differential scanning calorimetry and hot-stage polarized microscopy. The polymers were random copolyesters of p-hydroxybenzoic acid (from 60 to 10 mol %), catechol (from 20 to 45 mol %), and one of the following dicarboxylic diacids: terephthalic acid (series 1), 2,6-naphtalenedicarboxylic acid (series 2), and 1,2-bis-p-carboxyphenoxy ethane (series 3). Copolyesters with more than 25 mol % catechol in their structures were soluble in common organic solvents such as chloroform. All the synthesized copolyesters showed hysteresis of the heat capacity at the mesophase glass transition region and nematic mesophases above their T(g)'s which were stable over very broad ranges of temperature. Copolyesters containing the 2,6-naphtylenedioyl group showed the most stable nematic phases due to the increased anisometry of the 2,6-naphtylenedioyl unit compared to that of the therephthaloyl or the 4-oxybenzoyl units.