C60 fullerene aggregation in aqueous solution

In the present work we develop a novel approach for quantification of the energetics of C-60 fullerene aggregation in aqueous media in terms of equilibrium aggregation constant K-F. In particular, it is shown that the experimental determination of the magnitude of K-F is possible only within the framework of the 'up-scaled aggregation model', considering the C60 fullerene water solution as a solution of fullerene clusters. Using dynamic light scattering (DLS) data we report the value, K-F = 56 000 M-1, which is in good agreement with existing theoretical estimates and the results of energetic analyses. It is suggested that the proposed 'up-scaled model' may be used in any instances of non-specific aggregation resulting in formation of large spherical particles. The measurement of the translational diffusion coefficient and the dimensions of the light scattering particles using a DLS approach with respect to C-60 fullerene aggregates is found to contain significant systematic errors originating from the interaction effect that is well-known for micellar solutions. As a result, corrections to the equations associated with DLS data are proposed.