Studies on the Polymerization of Bifunctional Monomers. XIX. Radical Cyclopolymerization of Divinylformal

Radical polymerizations of divinylformal were carried out with AIBN initiator in several solvents. In many solvents (benzene, cyclohexane, acetonitrile, DMSO, etc.), the polymers consisted of the cyclized monomer unit and 5 to 8= of the pendant formate group. The amounts of the residual vinyl group were quite small in these solvents. The formate group was probably formed by the hydrogen migration and the subsequent ring scission of the cyclic propagating radical. On the other hand, a polymer obtained in CS 2 contained about 30= of the pendant vinyl group but no formate group. In addition, the carbon and hydrogen contents of this polymer were lower than expected, and sulfur was detected instead. The polymerization in benzene-CS 2 mixtures indicated a much stronger influence of CS 2 than benzene. These results suggest that CS 2 molecules interact strongly with the propagating radical to the extent that it can be incorporated into polymer.