Thermodynamics of synthesis of poly-(p,p′-dipenyleneoxide)pyromellitimide

The Experimental and Calculational Thermochemistry of 1,2,4,5-Benzenetetracarboxylic Dianhydride: Is This 10 π Multiring Species Aromatic?

“…A quick literature search (SciFinder) shows some 5000 references to the former species (and substituted derivatives) in the primary and (a majority to the) patent literature, many of which describe transformation to derivatives of the latter species as well as the ring-opened bis amide/bis carboxylic acid. Reflecting this multiple academic, commercial, and military interest in this species, there are three literature measurements of the enthalpy of formation of the solid cyclic dianhydride − as well as steps along the polymerization process. However, the results are sorely dissonant, −907.3, −1047, and −953.5 kJ mol -1 , respectively, from these sources.…”

Reaction Modeling of the Multistep Synthesis of Polyamic Acid from Pyromellitic Dianhydride and Oxydianiline

“…Poly(pyromellitimides) are generally made by the reaction of pyromellitic dianhydride (PMDA) and bifunctional diamine to form the soluble polyamic acid precursors, followed by the dehydrocyclization of the polyamic acids to polyimides (Kreuz et al, 1966(Kreuz et al, , 1967Sroog, 1967Sroog, ,1976Bower and Frost, 1963;Varga et al, 1979;Sroog et al, 1965). The thermodynamics and kinetics of the two separate stages have been extensively studied previously (Kreuz et al, 1966(Kreuz et al, , 1967Varga et al, 1979;Sroog et al, 1976; Karyakin et al, 1977;Sazanov et al, 1975;Tsimpris and Mayhan, 1973;Hodgkin, 1976). While the dehydrocyclization reaction is complicated due to the fact that chemical pathways can be quite different depending on if thermal or chemical method is practiced (Kreuz et al, 1966;Varga et al, 1979), the polyamic acid synthesis was deemed as a straightforward polycondensation reaction with several secondary reactions (Kolegov, 1977;Johnson, 1971).…”