Synthesis of aromatic polyimides in DMAc containing large amount of water and the properties thereof

A series of polyamic acids were prepared in N,N-dimethylactamide (DMAc) con taining large amount of water, some of which contain the amount of water up to 25%. Their inherent viscosities decreased with the increase of water in DMAc, depending on the electronic properties of dianhydride and reaction c ondition. The molecular weights and mechanical properties of the polyimides thermally imidized from the polyamic acids were almost independent on the water content in solvent. The decomposition-resynthesis of polyamic acids d uring the curing was also investigated.