Fullerene ‐ polymer complexes: fractal crossover in solutions

Poly(vinylpyrrolidone)(PVP)-tetraphenylporphyrin(TPP)-C 60 -complexes in heavy water at concentration C p = l wt.% have been studied at 293 K. Starting from PVP+TPP-complex and doping it with C 60 up to C∼6 wt.%, we recognised complexes' structural evolution. We observed the changes from mass fractals with dimension D M ∼2.3 at C=0 wt.% to surface fractals, having dimension D s ∼2.8 at C∼2 wt.%. Then the system returns to mass fractals, D M (C)∼2.9-2.8 at C∼5-6 wt.%. These structural peculiarities we explain as a result of cross linking action of fullerene, forming a microgel above a critical concentration C*∼1 wt.%. Meanwhile, the network of over-doped complex (C∼5 wt.%) is degraded, indicating a strong influence of fullerene on the water structure.