Studies of thermal cyclizations of polyamic acids and tertiary amine salts

Abstract Thermal conversion rates of the polyamic acid derived from pyromellitic dianhydride and 4,4′‐diaminodiphenyl ether are presented. Formation of the imide ring proceeds by fast and slow first‐order processes. Tertiary amines give ring closures faster by a factor of 10 than the free acid. The enhancement is an activation entropy rather than an activation energy effect.