FULLERENES IN SOLUTIONS

Information is given about the thermodynamic and kinetic singularities in the behavior of fullerenes in solutions. Experimental data are giv en on the solubility of fullerenes of different sorts in different sol utions in a wide temperature range. These data are analyzed on the bas is of the phenomenon of aggregation of fullerenes in solutions, which was predicted by me and later observed experimentally. A broad spectru m of phenomena are treated, which are associated with the formation in solutions of clusters that consist of a number of fullerene molecules . These phenomena include the recently revealed nonmonotonic temperatu re dependence of solubility of fullerenes in various solvents, nonline ar concentration dependence of nonlinear optical susceptibility of the third order, a sharp dependence of the coloring of fullerene solution on the composition of solvent, and the like. The above-identified phe nomena are analyzed on the basis of the drop model of cluster, which p rovides for a consistent thermodynamic description of the behavior of fullerenes in solutions. Experimental data are given on the diffusion coefficient of fullerenes in solutions. These data are analyzed from t he standpoint of the possibility of using them to describe the Stokes- Einstein formula. Proceeding from the cluster behavior of solubility o f fullerenes, the concentration dependence of the diffusion coefficien t of fullerenes in solutions is revealed. The possibility of using thi s latter dependence as a basis for a new method of separation and puri fication of fullerenes, including higher ones, is discussed. The possi bility is shown of the existence of thermal diffusion of fullerenes in solutions, based on the cluster behavior of their solubility. The res ults are given of calculations of the temperature and concentration de pendences of the thermal diffusion coefficient of fullerenes in soluti ons.