Static and dynamic light scattering study of strong intermolecular interactions in aqueous solutions of PVP/C60 complexes

The investigations of the dilute aqueous solutions of polyvinylpyrrolidone/fullerene (PVP/C60) complexes by static (SLS) and dynamic (DLS) light scattering showed that strong intermolecular interactions, effective on the distances of about 45–50 nm, take place in the solutions. Two concentration ranges are well distinguished in these solutions. Above a critical concentration (ccr) the fluctuations in the solutions are hindered and only one, diffusive, mode is observed in DLS experiments. Upon dilution (c<ccr) this unified structure divides into large fragments (domains) and the slow mode attributed to long-range concentration fluctuations, gradually appears. The angular and concentration dependencies of the diffusion coefficient of the slow mode indicate the existence of strong intermolecular interactions.