Flavone/Tertiary Amine as Free Radical Photoinitiator for UV Photopolymerization of Tripropylene Glycol Diacrylate(TPGDA)†

Abstract

The polymerization kinetics of tripropylene glycol diacrylate(TPGDA) was monitored by real time near infrared(RTIR) with favone(FL) as photosensitizer and different hydrogen donor as coinitiator.The commercial photosensitizer benzophenone(BP) was used as control.The results showed that the molar extinction coefficient(e max) of FL was much higher than that of BP.When FL was used in combination with tertiary amine hydrogen donor ethyl 4-N,N'-dimethylaminobenzoate(EDAB),the rate of polymerization(R p) and final double bond conversion(DC f) could reach 0.58 s-1and 97%,respectively,which was very close to that of commercial BP / EDAB system.However,using sesamin(SM) and benzodioxole(BDO) as coinitiator for FL,the R p and DC f were both very low,which indicated that the excited FL and tertiary amine could generate aminoalkyl free radical species via electron / proton transfer process and initiate the efficient photopolymerization of TPGDA.More importantly,when the co-polymerizable tertiary amines such as EBERYL P115 and dimethylaminoethyl methacrylate(DMEM) are used,the natural component characteristics of FL make it a promising photoinitiator in biomedical and food-packaging fields.