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

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.