New one-step synthesis of polyimides in salicylic acid

A new polymerization in the melt of salicylic acid has been developed for the one-step synthesis of polyimides from various diamines and dianhydrides. The polymerization is carried out in high solid content up to 40–50 wt/v% at 200 °C and affords the completely cyclized polyimides with high molecular weights in 1–2 h. The preliminary studies on some of the polymerization variables (e.g., concentration and time) suggest that the imidization is very fast and the chain growth is likely to proceed via the addition of the growing imide segments.