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 (Mn). Chemical structures of the polyamides were firmly established by means of NMR using CH-correlation techniques. The polymers are amorphous, with Tg's from 250–268°C, dependent on the TDI/MDI ratio. Thermal stability (weight loss onset around 400°C according to TGA measurements) suggests that melt processing may be feasible.
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Schotman et al. (1999) studied this question.
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