Long Wavelength Cationic Photopolymerization in Aerated Media: A Remarkable Titanocene/Tris(trimethylsilyl)silane/Onium Salt Photoinitiating System.

A new system for visible light induced polymerization of cationic resins working through it free radical promoted process under air is presented, This system is based on a fluorinated titanocene free radical initiator bis(cyclopentadienyl)bis[2,6-difluoro-3-(1-pyrryl)phenyl]titanium Ti, a silane (tris(trimethyl-Isilyl)silane TTMSS) together with ail onium salt (diphenyliodonium hexafluorophosphate). The polymerization process is highly efficient, and better under aerated than under laminated conditions; it appears as a suitable system for long wavelength cationic photopolymerization under air. This system could also be efficient for the polymerization under sunlight irradiation. The involved mechanisms investigated by laser flash photolysis and ESR spin trapping experiments are detailed.