Synthesis of aromatic polyamides from oligocarbodiimides and isophthalic acid

A new method to synthesize aromatic polyamides from oligocarbodiimides (derived from toluenediisocyanate (TDI) and 4,4'-diphenylmethanediisocyanate (MDI)) in N-methyl-2-pyrrolidone (NMP) as a solvent is described. Molar masses, based on end-group analysis and size exclusion chromatography, are in the order of 15 000-20 000 ((M) over bar(a)). Chemical structures of the polyamides were firmly established by means of NMR using CH-correlation techniques. The polymers are amorphous, with T-g's from 250-268 degrees C, dependent on the TDI/MDI ratio. Thermal stability (weight loss onset around 400 degrees C according to TGA measurements) suggests that melt processing may be feasible.