Direct polycondensation of aromatic tetracarboxylic acids with aromatic diamines in ionic liquids

The direct polycondensation of aromatic diamines and tetracarboxylic acids was studied using imidazolium-type ionic liquids as the reaction medium. Polyimides with inherent viscosities of 0.05 dL g(-1) could be prepared in high yields by this novel polycondensation at 150 degrees C for 12 h without polyamic acids. In this reaction, ionic liquids could catalyze the condensation and cyclodehydration reaction of dicarboxylic acids and amines to directly give imide rings.