This is the first report of the synthesis of well-defined disubstituted polymer derivatives of C-60 by a radical mechanism. Narrow-polydispersity polystyryl adducts with TEMPO (2,2,6,6-tetrametylpiperidinyl-1-oxy), prepared by the nitroxyl-mediated "living" radical polymerization technique, were heated with a 4-fold excess (in molar ratio) of C-60 in o-dichlorobenzene at 145 degrees C to give 1,4-dipoly-styryldihydro[60]fullerenes (yields 60-80%). A low-mass model compound 2-benzoyloxy-1-phenylethyl adduct with TEMPO gave essentially the same result. These disubstituted derivatives retained the redox properties of C-60 and gave UV-vis spectra characteristic of 1,4-bisadducts. A possible mechanism by which disubstituted derivatives are selectively produced was discussed.