Synthesis and characterization of polyisoprene-poly(methyl methacrylate) AB diblock and A2B2 heteroarm star copolymers

The synthesis of A(2)B(2) heteroarm stars, where A is polyisoprene (PI) and B is poly(methyl methacrylate) (PMMA) has been achieved using living anionic polymerization. A divinyl coupling agent 1,1-(1,2-ethandiyl)bis(4-(1-phenylethenyl)benzene) (EPEB) was used to link together polyisoprenyllithium chains and create a dianion from which methyl methacrylate (MMA) polymerization could be initiated and thus form a four-armed star. PI-PMMA diblocks were synthesized by sequential anionic polymerization. Characterization was performed using size exclusion chromatography (SEC), H-1 NMR, and membrane osmometry. Hydrogenation of the polymers using toluenesulfonyl hydrazide yielded the corresponding poly(ethylene-alt-propylene)-PMMA stars and diblocks.