Grafting Methyl Methacrylate onto Styrene-Butadiene-Styrene Tri-Block Copolymer in Supercritical Carbon Dioxide

Grafting methyl methacrylate(MMA) onto styrene-butadiene-styrene tri-block copolymer(SBS) was carried out by free radical polymerization using supercritical carbon dioxide as a solvent of MMA and swelling agent for SBS. The grafting ratio reached to 26.3%.The effects of reaction conditions,such as monomer concentration,initiator concentration,supercritical CO_2 pressure and the reaction time on the grafting ratio were studied.The products were characterized by FT-IR,GPC,DSC and SEM.GPC data show that the molecular weight of SBS-g-MMA is higher than that of SBS.DSC testing indicates that the glass transition temperature of SBS-g-MMA is higher than that of SBS.