Chemical Initiation of Graft Copolymerization of Methyl Methacrylate onto Styrene–butadiene Block Copolymer
Journal of Polymer Science: Part A, Polymer Chemistry
When a solution containing both styrene–butadiene block copolymer (SBS) and methyl methacrylate is treated with an initiator both homopolymerization of the methyl methacrylate and graft copolymerization of the methyl methacrylate onto the SBS occur. The amount of graft copolymerization depends upon the time and temperature of the reaction, the concentrations of all species, and the identity of the solvent and initiator. The combination of benzoyl peroxide in chloroform gives the highest graft yield and the reaction occurs by removal of an allylic hydrogen from the SBS by the initiator radical and subsequent addition of monomer units to that site; there is a significant solvent effect. Both AIBN and BPO function by the removal of an allylic hydrogen atom from SBS; BPO is able to effect this reaction relatively easily while AIBN can remove the hydrogen atom only with great difficulty and to a limited extent.