Influence of nanoparticles of various types as fillers on resistance to hydrolysis of films of heat-resistant polyimide

Impact of nanoparticles of various types as fillers on the stability of the poly(pyromellitimide)-based nanocomposite films’ properties in alkaline hydrolysis was studied. It was shown that the introduction of nanoparticles into the polymer can lead to an increase in excess free volume. This fact is evidenced by scanning electron microscopy and densitometric studies. The increase of the excess free volume was shown to provoke a rise of the diffusion intensity of the hydrolyzing agent in the films volume during their exposure to an alkaline medium. This effect leads to film swelling and, thereby, to increases of the intensity of the destructive action of hydrolysis on the material. Chemical surface pretreatment of the nanofiller allows one to obtain a composite with an increased packing density compared to that for a composite with unmodified nanoparticles. However, the hydrolytic stability of such a film still remains somewhat inferior to that of the pristine polyimide.