Asymmetric and mikto-arm stars with a C60 core by grafting of macro-radicals or anionic polymer chains

Asymmetric and mikto-arm stars were synthesized by the stepwise addition of macro-radicals or of anionic polymer chains onto C60. Pure di-adducts (PSa)2C60 were obtained by atom transfer radical addition of a Br-terminated polystyrene (PSaBr). Tetra-adducts (PSa)2C60(PSb)2 and (PSa)2C60(PI)2 were prepared by grafting, respectively, two additional PSbBr or PIBr onto (PSa)2C60. The addition of 'living' polystyryllithium onto C60 can be stoichiometrically controlled. For example, the reaction of four PSaLi with one C60 led to the formation of (PSa)4C604−(Li+)4. The additional grafting of polystyryllithium (PSbLi) or polyisoprenyllithium (PILi) provided, respectively, (PSa)4C60(PSb)2 and (PSa)4C60(PI)2. All the stars were characterized using multiple detectors size exclusion chromatography (SEC).