Modeling the cyclopolymerization of diallyl ether and methyl α-[(allyloxy) methyl]acrylate

The free-radical cyclopolymerization of diallyl ether (1) and methyl α-(allyloxymethyl)acrylate (2) has been modeled with the B3LYP/6-31G* methodology, by making use of model compounds for the growing radicals. The cyclization of both monomers is exo, with activation barriers of 5.33 and 9.82 kcal/mol, respectively. To account for the polymerizabilities of these monomers, competing reactions have also been modeled. Although both monomers have a lower barrier for homopolymerization than for cyclization, cyclization dominates due to entropy. This explains the high cyclopolymerization vs. homopolymerization of monomer 2, although its monofunctional counterpart has been reported to homopolymerize well. It has also been shown that the degradative chain transfer by H-abstraction from the allylic carbon is not effective with this monomer. Poor cyclopolymerization of the monomer 1 has been demonstrated by modeling the degradative chain transfer by H-abstraction from the allylic carbon, which has been shown to compete very efficiently with polymerization reactions. Additionally, intermolecular propagation reaction has been shown to be facile due to cyclization, since the attacking monomer adopts a cyclic structure.