Synergistic Free Radical Effects in Photoinitiated Cationic Polymerization

摘要

Aryl free radicals produced by the photolysis of an onium salt photoinitiator can be used to accelerate the rates of photoinitiated cationic vinyl and ring-opening polymerizations. Secondary radical species generated by reaction of aryl radicals through hydrogen abstraction or by addition to double bonds of the monomer are oxidized to cations by onium salts. Fragmentation of the reduced onium salt produces radical species that participate in a non-photochemical chain process the generates additional cations. The increased number of initiating cationic species accounts for the observed acceleration effect.