XPS study on the thermal degradation of poly‐N,N′/4,4′‐diphenylether/pyromellitimide

Thin foil samples of the title polymer preheated in vacuo up to different temperatures with the highest one reaching 1200 K were analysed by XPS. On heat treatment the surface content of oxygen decreased and that of carbon increased monotonously, while that of nitrogen passed over a local maximum at c . 800 K. Ether‐type oxygens proved to be more heat resistant than carbonyl type ones. From the change of the N 1s peak the probable mechanism of decomposition up to c . 800 K was inferred to be a decarboxylation to give CHN type structures. At higher temperatures decarbonylation of the imide groups appeared to become predominant, resulting in the formation of amide functionalities. The development of a conductive (polyaromatic) structure was deduced from the gradual decrease in the charge shift with the increase of the temperature of pretreatment.