Association behaviors of poly(N-vinylpyrrolidone)-grafted fullerenes in aqueous solution

Poly(N-vinylpyrrolidone) (PVP)-grafted fullerenes (PVP-C60 and PVP-C70) were synthesized by iniferter polymerization in order to fabricate water-soluble fullerene containing micelles. PVP-C60 formed micelles with hydrodynamic diameters ranging from 15 to 33 nm. The solubilization of fullerene molecules into the core of the PVP-C60 micelles was also found to control the size of the micelles. By increasing the amount of added fullerene, we gradually increased the micelle size before drastically increasing it to that of 200 nm in hydrodynamic diameter. The drastic change occurred at a critical value of the added C60/PVP monomer ratio, almost independently of the molecular weight of PVP.