Radical cyclocopolymerization of divinyl ether derivatives with maleic anhydride. The structure determination of the alternating copolymers by ¹³C-NMR spectroscopy

Radical copolymerizations of cis-propenyl vinyl ether, 2-methylpropenyl vinyl ether and cis-dipropenyl ether with maleic anhydride were carried out, and completely cyclized, and alternating copolymers were obtained with the 1: 2 composition of divinyl ethers and maleic anhydride. ¹³C-NMR spectroscopic data indicated that the polymers contained in common the bicyclic unit composed of one molecule of each monomer and the maleic anhydride unit. The bicyclic unit was characterized by the cis junction and the trans ring closure, and the maleic anhydride unit was formed by trans opening of the double bond. Introduction of methyl substituents do not appear to affect the polymer structure, though assignments become less definite.