Dye photosensitized cationic ring-opening polymerization: Search for new dye skeletons

New dyes (based on diamine, oligophenylenevinylene, salphen ligands and polyazine skeletons) are checked here for the formation of free radicals under very soft irradiation conditions (halogen lamp, blue or green LED bulbs and laser diode at 457 nm) under air. Three component systems involving a combination of diamine (or oligophenylenevinylene) dye/diphenyl iodonium salt/silane (or N-vinylcarbazole NVK) are used. Excellent ring-opening polymerization ROP profiles are obtained. A comparison of the ability of these dyes vs. Eosin-Y (used as a well known reference dye) is also provided. The chemical mechanisms are investigated in detail by ESR and luminescence experiments. Upon a visible light exposure, these systems generate aryl, silyl or αN radicals that can be easily oxidized to promote the ring-opening polymerization of epoxy monomers. In every case, the silyliums (R3Si+) or the N-vinylcarbazole derived cations (NVK+) are the polymerization initiating structures.