GRAFTING OF ANIONIC POLYMERS ONTO C-60 IN POLAR AND NONPOLAR-SOLVENTS

The mechanism of addition of various ''living'' anionic polymers on C- 60 has been investigated in apolar and polar solvents, and well-define d star-shaped macromolecules with a C-60 core have been prepared. In t oluene, only addition of the carbanions onto double bonds on the fulle rene is observed. The maximum number of grafted chains depends on the reactivity of the carbanion borne by the chain; this value is six for the very reactive ''living'' polystyrene and polyisoprene but only thr ee using the more stable diphenylalkyl carbanion. The number of grafts can be, to some extent (3-6), controlled by stoichiometry. In THF, th e reaction mechanism is more complicated: 2 electrons ape first transf erred from the carbanions to the fullerene producing the C-60 dianion and then addition takes place. The number of grafted chains depends no t only on the reactivity of the carbanion but also on its ''bulkiness' ': four chains are grafted with tile carbanion styryl, three with 2-vi nylpyridyl, and none using diphenylethyl.