ONIUM BUTYLTRIPHENYLBORATES AS DONOR-ACCEPTOR INITIATORS FOR SENSITIZED PHOTOPOLYMERIZATIONS OF VINYL MONOMER

Donor-acceptor initiators, onium butyltliphenylborates (DPIB, DMPSB) c ontaining both an onium cation (electron-accepting radical generator) and a berate anion (electron-donating radical generator) within the sa me compound were able to be sensitized by two aromatic ketones (2-chlo rothioxanthone and Michler's ketone) to initiate polymerization of tet rahydrofurfuryl acrylate monomer. The photopolymerization efficiency o f the onium butyltriphenylborates was higher than that of the onium sa lts (DPI, DMPS) or the berate compound (TBAB). The photoinitiation pro cesses between the photosensitizers and the initiators have been inves tigated by laser flash photolysis. It has been clarified that two kind s of radical species are generated by a photoinduced electron-transfer mechanism.