X-ray photoelectron spectroscopy and infrared spectroscopy analysis of pyromellitic dianhydride–oxydianiline polyamide-acid and polyamide-ester imidization

Abstract

Pyromellitic dianhydride–oxydianiline amide-acid (PMDA–ODA–acid) and amide-ester (PMDA–ODA–ester) imidization was studied using x-ray photoelectron spectroscopy (XPS) and infrared spectroscopy. The data show that the PMDA–ODA–acid bulk and surface have imidized significantly already after 150 °C exposure, while PMDA–ODA–ester shows no imidization until 230 °C exposure. PMDA–ODA–acid reaches maximum bulk and surface imidization after exposure to 200 °C, while the PMDA–ODA–ester requires 300 °C exposure before maximum imidization is reached. The XPS analysis also shows that the PMDA–ODA–acid has two nitrogen 1s species, one at 400 eV due to imide species and another at 399.3 eV possibly due to isoimide species, while the PMDA–ODA–ester shows only a single nitrogen 1s peak at 400.9 eV due to imide species.