Coinitiators Based on Group 14 Elements in Photoinitiating Systems for Radical and Cationic Polymerization

New co-initiators based oil group 14 elements (disilanes, polysilanes, digermanes, distannanes) are proposed. Under their photosensitized excitation, in the presence of benzophenone BP or a thiopyrylium salt TP, a metal-metal bond cleavage is observed. The generated radicals are excellent initiating species for free radical photopolymerization, FRP, and free radical promoted cationic photopolymerization, FRPCP. In FRP, when working both in laminate and under air, the new combinations are found highly reactive and, in most cases, better than the BP/ethyl dimethylaminobenzoate or Eosin/methyldiethanolamine reference systems. Their ability in FRPCP under air is also found excellent. The associated mechanisms are questioned oil the basis of laser flash photolysis and ESR experiments.