CLUSTER ORIGIN OF FULLERENE SOLUBILITY

The possibility of the existence of fullerenes in organic solvents in the form of clusters containing a number of fullerene molecules is dis cussed. A theory is developed on the basis of a droplet model for clus ters, which enables one to describe the distribution function of clust ers by size and to obtain the non-monotone temperature dependency of f ullerene solubility observed recently. It is shown that a phase transi tion taking place in a crystalline C-60 at T-c similar or equal to 260 K significantly changes the role of clusters in solution. At T > T-c the distribution function of clusters, characterized by the number n o f constituent molecules, has its maximum at n = 11 and higher, while at T < T-c the value of n similar or equal to 3-5. This is the reason for the different temperature dependencies of fullerene solubility in various temperature ranges. Comparison of the calculated values of so lubility with experimental data permits one to obtain energetic parame ters characterizing the interaction of a fullerene molecule with its s urrounding in a solid phase or a solution.