Synthesis of Polymethyl Methacrylate Grafted Styrene-butadiene-Styrene Triblock Polymer via Atom Transfer Radical Polymerization and its Characterization

Grafting of poly (methyl methacrylate) (PMMA) onto styrene-butadiene-styrene (SBS) triblock copolymer (SBS-g-PMMA) was synthesized by atom transfer radical polymerization (ATRP). The hydroxylated SBS (SBS-OH) was synthesized firstly by the reaction of SBS and formic acid/peroxide hydrogen. After esterification reactions between -chloroacetic chloride and hydroxyl side groups, the chlorinated SBS (SBS-Cl) was obtained. Then the SBS-Cl was used as a macroinitiator to initiate the graft polymerization of MMA in the presence of CuBr and N,N,N',N',No-Pentamethyldiethyltriamine (PMDETA) to get SBS-g-PMMA. The structure of SBS-g-PMMA was characterized by fourier transform infrared spectrometer (FTIR) and proton nuclear magnetic resonance (1H-NMR), and the results confirmed that MMA was grafted. The properties of the product were characterized by gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and atomic force micrograph (AFM). The molecular weight distribution of SBS-g-PMMA was as narrow as 1.17 measured by GPC. TGA data showed that the thermal stability of SBS-g-PMMA was improved. By AFM images, the structure of micro-phase separation could be observed obviously.