Synthesis and characterization of aromatic polyimide and polyamide‐imide from 2,5‐bis(4‐isocyanatophenyl)‐3,4‐diphenylthiophene and aromatic tetra‐ and tricarboxylic acids

Abstract Soluble polyimide having an inherent viscosity up to 1.4 dL/g was synthesized by the high‐temperature solution polycondensation of 2,5‐bis(4‐isocyanatophenyl)‐3,4‐diphenylthiophene with 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride. The polycondensation of the tetraphenylthiophene diisocyanate with trimellitic anhydride afforded polyamide‐imide with an inherent viscosity up to 0.9 dL/g. These polymers showed limited solubility in organic solvents and had glass transition temperatures around 320°C.