Asymmetric and mikto-arm stars were synthesized by the stepwise addition of macro-radicals or of anionic polymer chains onto C-60. Pure di-adducts (PSa)(2)C-60 were obtained by atom transfer radical addition of a Br-terminated polystyrene (PSaBr). Tetra-adducts (PSa)(2)C-60(PSb)(2) and (PSa)C-60(PI)(2) were prepared by grafting, respectively, two additional PSbBr or PlBr onto (PSa)(2)C-60. The addition of ' living ' polystyryllithium onto C-60 can be stoichiometrically controlled. For example, the reaction of four PSaLi with one C-60 led to the formation of (PSa)(4)C-60(4-) (Li+)(4). The additional grafting of polystyryllithium (PSbLi) or polyisoprenyllithium (PILi) provided, respectively, (PSa)(4-) C-60(PSb)(2) and (PSa)(4)C-60(PI)(2): All the stars were characterized using multiple detectors size exclusion chromatography (SEC). (c) 2005 Elsevier Ltd. All rights reserved.