A mechanistic study of polyimide formation from diester‐diacids

Abstract

Abstract Previous work by a number of researchers has noted the presence of anhydride during the imidization step of polyimide polymer processing from diester‐diacids and diamines. This has been often, and incorrectly, dismissed as being due to the reversion of the intermediate amide‐acid. Comparison of the relative rates of reactions among model compounds demonstrates the intermediacy of anhydride in the imidization reaction. When creation of the anhydride is blocked, the production of amide‐acid is greatly slowed. Infrared and NMR observations of mixtures of monomers confirm the production of anhydride as a necessary intermediate in the imidization reaction occuring during the production of polyimide polymers from diester diacids.