Synthesis and polymerization of methyl 3-methylenecyclobutene-1-carboxylate and dimethyl 3-methylenecyclobutene-1,2-dicarboxylate

The two title monomers were synthesized. In both cases the key cyclobutane intermediates were obtained by cycloaddition of allene to acrylonitrile or chloromaleic anhydride. These two new monomers proved to be highly reactive in free radical polymerization, and each polymerized spontaneously in air at room temperature. Linear polymers were prepared in dimethyl sulfoxide solution at 35° with AIBN and UV light. At higher temperatures crosslinking became a problem in some instances. The structure of the polymers derived from 1,4 polymerization in the diene portion of the monomers was confirmed by ¹³C-NMR, ¹H-NMR and IR spectra. Copolymers were prepared with methyl methacrylate, styrene, and p-methoxystyrene and were always rich in the methylene-cyclobutene monomers used. Films of homopolymers and copolymers could be cast from chloroform solution.