A novel visible-light sensitive ion-pair photoinitiation system diphenyliodonium salt of ethyl esterified eosine has been synthesized and studied.The results showed that its physicochemical properties and photoinitiation efficiency are influenced by its structure

concentration and the properties of the media in which it is in.When exposed to visible light

the photoinitiated electron transfer from the anion to the cation took place

producing initiating phenyl radical and terminating ethyl esterified eosine radical.The kinetic equation of photopolymerization of vinyl monomers with this photoinitiator

molecular weight and distribution have been measured.Finally comparison of the monoiodonium and bisiodonium salts of eosine have been carried out.