GRAFTING OF METHYLMETHACRYLATE ONTO RAYON USING Ag+-S2O8--SYSTEM AS INITIATOR

It is well known that Ce+4 initiates the graft polymerization of various vinyl monomers onto cellulose.We have found that the redox system consisted of Ag+ and S208-- also initiates the grafting onto cellulose easily in aqueous system at room temperature.In the present report, the rate of grafting of methylmethacrylate (MMA) onto rayon has been studied using various amount of AgNO3 and K2S2O8.The results obtained are as follows;1) When the concentration of MMA remains constant, both the initial rates of total polymerization and grafting are determined by [Ag+]×[S2O8--].2) At the concentration of initiator between 0.02 and 2.5 (m. mol/100 cc), although the rate of total polymerization is roughly proportional to ([Ag+]×[S208--])1/2, the rate of grafting is proportional to [Ag+]×[S208--].3) The efficiency of grafting is consequently roughly proportional to ([Ag+]×[S208--])1/2 from the above results.The probable mechanism of initiation of grafting is the oxidation of cellulose by Ag++ resulted from the reaction of Ag+ with S208--.In the case of total polymerization, termination occurs probably by the reaction of two chain radicals, but the termination of grafting is supposed to arise from the chain transfer reaction with monomer or solvent (H2O).