The grafting mechanism of poly(vinyl acetate) macroradicals prepared by
cobalt-mediated radical polymerization (CMRP) onto C60 is investigated.
Experimental conditions such as the polymerization mechanism, the
temperature and the stoichiometry directly impact the grafting mechanism
and the nature and stability of the final products.
Mixtures of PVAc/C60 adducts having between one and eight polymer chains per C60 are formed. C60 has a well-known radical scavenging ability.
PVAc/C60 adducts prepared with low [PVAc]:[C60] ratios may contain weak C60-C60
bonds that further dissociate and account for the instability of the
products. The formation of such dimers can be lessened by increasing the
temperature from 30°C to 100°C. The temperature increase also allows a
complete dissociation of the PVAc-Co dormant species into PVAc°
macroradicals and an almost quantitative grafting of eight PVAc chains
onto C60, leading to well-defined C60(PVAc)8 octa-adducts.