| Abstract: | The bulk polymerization of maleic anhydride initiated with acylperoxides, di-tert-butyl peroxide, AIBN, or pyridine proceeds with evolution of CO2. The amount of CO2 generated depends on the nature and the concentration of the initiator. With peroxide initiators, less than 5% of the polymerized maleic anhydride is decarboxylated. 1H-NMR spectra, obtained on the benzoyl peroxide-initiated polymer and its methyl ester, are consistent with the unrearranged poly(maleic anhydride) structure and rule out the polycyclopentanone structure proposed by Braun and co-workers. Base-initiated polymaleic anhydride is substantially decarboxylated, and the resulting polymer has anhydride and carboxyl groups. Elemental analyses and 1H-NMR spectra obtained on the pyridine-initiated polymer and its methyl ester refute both the cis-poly(vinylene ketoanhydride) structure suggested by Schopov and the polycylopentanone structure proposed by Braun and co-workers. |
