BODIPY derivatives and boranil as new photoinitiating systems of cationic polymerization exhibiting a tunable absorption in the 400–600 nm spectral range

Novel photoinitiators based on the BODIPY and boranil chromophores being able to photosensitize the iodonium salt decomposition are proposed for the cationic polymerization of epoxy, epoxy-silicone and vinyl ether monomers under exposure to laser diodes at 405, 457, 473 and 532 nm. They allow an interesting tunability of the absorption in the 400–600 nm wavelength range. Quite excellent polymerization profiles are recorded with final conversions up to 90%. Addition of N-vinylcarbazole (NVK) can also greatly enhance the performance. ESR and steady state photolysis experiments show the generation of aryl radicals and cation radicals. The observed mechanisms are discussed.