Surface analysis of aromatic polyimide films using ESCA

C 1s, N 1s and O 1s core spectra were measured for well‐cured polyimide films of poly( N , N ′‐(p,p′‐oxydiphenylene)promellitimide), and of poly( p , p ′‐oxybis(phenylene)‐3,3′,4,4′‐benzophenonetetracarboxylimide). Resolvable were: multiple C 1s, two N 1s and two O 1s components. A carbonyl deficiency not due to X‐ray‐induced decarboxylation was detected. Approximately 45% of the surface carbon matrix was found to be comprised of partially oxidized, non‐carbonyl‐containing moieties of unknown origin. C 1s chemical shift behavior showed that imide bond formation does occur on curing; the imidization reaction in the surface region is incomplete (or altered) based on the changes in the O 1s and N 1s data with increasing temperature of curing. A surface chemical structure inconsistent with the bulk structural formula is observed.