Radical cyclopolymerization of divinyl ethers. The polymerization kinetics and the polymer structure

The radical polymerizations of divinyl ether (DVE), cis-propenyl vinyl ether (PVE) and 2-methylpropenyl vinyl ether (CH₃-PVE) were carried out with AIBN initiator. The polymers were composed of five-membered monocyclic units with pendent unsaturated groups and [3, 3, 0]bicyclic units. The bicyclization was favored at low monomer concentrations and with methyl-substituted monomers. The microstructures of the polymers were determined by ¹³C-NMR spectroscopy, through extensive use of the model compounds. A common cyclopolymerization process has emerged from the data obtained. The monomers react exclusively at the unsubstituted vinyl group, and the trans ring closure produces five-membered monocyclic radicals which then propagate intermolecularly or cyclize to give trans-fused bicyclic units.