Highly conjugated visible and near-infrared light photoinitiating systems for radical and cationic polymerizations

In this communication, we report highly conjugated thiophenes having [1,2,5]-thiadiazolo and [1,2,5]selenadiazolo [3,4-f]-benzo [1,2,3] triazole in conjunction with diphenyliodonium hexafluorophosphate salt (DPI) as new visible and near-infrared light (NIR) photoinitiator systems for free radical (FRP) and cationic polymerizations (CP). The postulated mechanism is based on the electron transfer reactions between the excited conjugated molecule and DPI ions. The radicals and Bronsted acid formed this way initiate FRP and CP of appropriate monomers such as methylacrylate (MA), methyl methacrylate (MMA), triethylene glycol dimethacrylate (TEGDMA) and cyclohexene oxide (CHO), isobutyl vinylether (IBVE) respectively. The possibility of in situ hybrid polymerization is also demonstrated using bifunctional monomer glycidyl methacrylate (GMA).