On the relationship between the fullerene reactivity and degree of substitution

Resumo

The kinetics of radical polymerization of N-isopropylacrylamide (NIPA, initiator of AIBN) in the presence of some C₆₀ derivatives was studied. It was established experimentally and by quantum chemical calculations that the ability of fullerene to add radicals decreased sharply after the destruction of six double bonds in the C₆₀ molecule due to the addition of six free radicals or other particles. The calculations show that the energy of bond formation between the seventh initiator radical and C₆₀ is by 20 times lower than that in the case of previous six radicals, and the further addition of radicals is impossible. It was experimentally found that the maximally possible number of added initiator radicals can be much higher. Moreover, during radical polymerization of NIPA a polymer layer grows around the C₆₀ molecules with maximally possible number of already added initiator radicals. The layer consists of polymer NIPA chains chemically bound with C₆₀. A possible mechanism explaining this fact is discussed.