Synergistic effects in hybrid free radical/cationic photopolymerizations

Multifunctional alkyl glycidyl ether and oxetane monomers are usually deemed to be poorly reactive and are consequently of limited use for high speed photocuring applications. However, these monomers can be made to undergo exceedingly rapid exothermic photopolymerization when combined with a multifunctional acrylate monomer and a corresponding free radical photoinitiator. Under optimum UV irradiation conditions, these hybrid photopolymerizations take place rapidly and substantially without an induction period. A mechanism was proposed on the basis of thermal acceleration of the cationic ring-opening polymerizations induced by the fast exothermic free radical acrylate photopolymerization. (C) 2007 Wiley Periodicals, Inc.