Abstract
Here, I review our recent study on concurrent cationic vinyl-addition and ring-opening copolymerization of vinyl ethers and oxiranes in terms of the factors that are required for successful crossover propagation reactions between the different types of monomers. A vinyl monomer does not add to the oxonium ion derived from an oxirane; hence, carbocationic species have to be generated through ring-opening reaction of the oxonium ion for the crossover reaction from oxirane to vinyl ether. The results of copolymerization reactions using various oxirane monomers suggest that appropriate substituents on oxiranes are responsible for the efficient generation of carbocationic species. Moreover, weak Lewis bases such as ester and ether promote the ring-opening reaction of oxonium ions through a nucleophilic attack on the carbon atom adjacent to the cationic oxygen atom. This article also summarizes concurrent cationic vinyl-addition, ring-opening, and carbonyl-addition terpolymerization through a one-way cycle of crossover reaction, copolymerization using an alkoxyoxirane monomer, and controlled copolymerization of vinyl monomers and cyclic formals.
