The alternating copolymerization mechanism of vinyl esters with maleic acid derivatives

The mechanism of the chain propagation in alternating copolymerizations has been studied on monomers of similar chemical composition, namely the acceptors (diethyl maleate-DEM and maleic anhydride-MA) and donors (vinyl phenylate-VP and vinyl butylate-VB). The ESR method has shown the chain propagation in the system DEM-VP and MA-VP to be an alternating addition of the monomer molecules to the growing macroradicals, although some donor-acceptor comonomer complexes were found in the latter case to be present in solution; the chain propagation in system MA-VB is an addition reaction between the binary comonomer complexes. The studied pairs of monomers were found to have a change of the chain propagation mechanism from a consecutive addition of the individual monomers to one in which the binary donor-acceptor complexes add on to the growing radicals as the donor acceptor reaction increases in intensity.