SYNTHESIS AND CHARACTERIZATION OF A PURELY RANDOM THERMOTROPIC TERPOLYMER BASED UPON PARA-ACETOXYBENZOIC ACID, HYDROQUINONE DIACETATE, AND AZELAIC ACID

A purely random main-chain thermotropic polyester analogous to that obtained by polymerizing 4'-acetoxyphenyl 4-acetoxybenzoate and azelaic acid was synthesized by the terpolymerization of p-acetoxybenzoic acid, hydroquinone diacetate, and azelaic acid. Differential scanning calorimetry (DSC), solution viscosity, optical polarizing microscopy, carbon-13 nuclear magnetic resonance (C-13 NMR), and wide-angle X-ray diffraction (WAXD) measurements were used to characterize the polymer. C-13 NMR measurements showed a higher degree of randomness for the polymer obtained by this three-monomer method than for the random polymer obtained by the previously reported two-monomer method. DSC analysis of low molecular weight polymer (IhV < 0.30) revealed two thermal transitions associated with the crystalline- to nematic-phase transition. As the molecular weight of the polymer was increased, a third transition became apparent. This third transition increased in intensity with increasing IhV and was shown by WAXD measurements to be a transition other than the crystal-nematic transition, which has been hypothesized for similar systems.