Thermally initiated cationic frontal polymerization of epoxies and vinyl ethers through a lone onium salt

Frontal polymerization (FP) of epoxy monomers is typically achieved with a radical-induced cationic frontal polymerization (RICFP) process that combines a thermal radical initiator with an onium salt superacid generator. In this paper, we show that both thermal and UV-initiated cationic frontal polymerizations are possible for common epoxy and vinyl ether monomers with only an iodonium superacid generator in the absence of a standalone thermal radical initiator. Increasing superacid generator concentration resulted in an increase in front velocity, as did the addition of vinyl ether to epoxies. The front velocity is reduced by the addition of 4-methoxyphenol (MeHQ), indicating free-radicals play a significant role. image