A Raman Spectroscopic Study of Vapor Deposited Poly(N,N'- bis(phenoxyphenyl)pyromellitimide) Films

Raman spectra have been obtained for thin (ca. 200 nm) poly(N,N'- bis(phenoxyphenyl)pyromellitimide) films produced by co-deposition of 4,4'- oxydianiline and pyrometallic dianhydride onto polycrystalline copper substrates from the vapor phase. It is demonstrated that even severe overdosing with one of the starting materials produces material which, after curing, is spectroscopically identifiable as polyimide. The details of the spectra obtained are, however, variable according to the dosing and curing conditions and, in some cases are substantially different from those characteristic solutions cast films. These differences are attributed to the presence of reaction products formed by the attach on imide carbonyls by unreacted amines in the matrix to form branched polymer chains. Imides.