Preparation of Polyimide Films Derived from a Novel Precursor Pre-imidized Poly(amic acid) Ammonium Salt

摘要

In this paper, a series of polyimide films were prepares through a novel precursor pre-imidized poly(amic acid) ammonium salt (PI-PAAS). The chemical structure of PI-PAAS films was confirmed by 1H NMR, and the degree of pre-imidization was confirmed by FT-IR spectra. And the intrinsic viscosity of the PI-PAAS solution was not distinctly changed after 90 days, while the viscosity of poly(amic acid) (PAA) obviously decreased with storage time. It was suggested that hydrolytic stability of PI-PAAS was significantly improved as compared with that of PAA due to the shielded carboxyl groups on PI-PAAS, which prevented the molecular chain of the polymer from decomposition. Moreover, PI films derived from PI-PAAS precursors possessed superior mechanical properties.