Photoinduced and Thermally Induced Cationic Polymerizations Using Dialkylphenacylsulfonium Salts

A study of the photoinitiated and thermally initiated cationic polymerizations of several monomer systems using dialkylphenacylsulfonium salt (DPS) photoinitiators bearing different alkyl chains and anions has been conducted. DPS compounds are capable of photoinitiating the cationic polymerization of a wide variety of epoxy and vinyl ether monomers directly on irradiation with UV light or by using visible light irradiation in the presence of photosensitizers. Kinetic studies show that DPS photoinitiators compare favorably with respect to their reactivity to diaryliodonium and triarylsulfonium salt photoinitiators in the polymerization of epoxides. The photopolymerizations of vinyl and 1-propenyl ethers display a marked induction period consistent with termination of the growing chains by reaction with the photogenerated ylides. Preliminary studies have demonstrated that DPS can also be employed as thermal initiators for the cationic ring-opening polymerization of epoxides at moderate temperatures.