Abstract: Eosin dye (EO)-diphenyliodonium salt(DPIO) system has been synthesized as a new dye photoinitiator sensitive to visible spectral region. Its maximum absorption is at 527nm. The eosiniodonium system does not react in the dark.but on irradiation with visible light,the photoinduced electron transfer sensitive reaction may lead to the bleaching of dye and cleavage of iodonium. The produced free-radicals could initiate the curing of acrylate film composed of epoxy 6101 diaerylate and pentaerythritol triacrylate (2:1W/W). The photocuring rate was found to be depended strongly on the composition of the system. The diiodonium salts EO (Ph₂I)₂ appeared more effective than monoiodonium salt EOEt (Ph₂I), while the bimolecular system (EONa₂+Ph₂I⁺BF₄^-) failed to cause any crosslinking reaction in the same coudition. It may be concluded that the photoinduced electron transfer photosensitization by the ion-pairs is a high efficient pathway to overcome the diffusion controlled limitation.

Key words: eosin-iodonium salt, acrylate, photocuring, photoinduced electron transfer sensitiation