Photopolymerization of 1,6-hexanediol diacrylate with deoxybenzoin as photoinitiator

Abstract Rates of the photopolymerization of 1,6-hexanediol diacrylate (HDODA) using deoxybenzoin (DOB)/amine photoinitiator systems have been measured. Triethylamine (TEA), N , N -dimethylethanol amine (DMEA), N , N -dimethylaminoethyl methacrylate, and N , N -diethylaminoethyl methacrylate (DMEMA) are postulated to form excited state complexes (exciplexes) with DOB from whence photoreduction of DOB occurs to give the ketyl radical (identified by laser flash photolysis) and an initiating radical species. Rate enhancements on the order of 5 to 7 are reported both in nitrogen and air-saturated HDODA. Thus, deoxybenzoin which acts as a rather poor cleavage type photoinitiator in the absence of a hydrogen-donating species, becomes an effective co-photoinitiator when used in conjunction with tertiary amines.