Dependence of the dimension of the associates of water-soluble tris-malonate of light fullerene C60[=C(COOH)2]3 in water solutions at 25oC

Abstract

Investigation of the concentration dependence of the size and type C₆₀[=C(COOH)₂]₃ aggregation in aqueous solutions at 25 ^◦C was accomplished with the help of a dynamic light scattering method. It was determined that three types of aggregates are realized in the solutions. The average number of C₆₀[=C(COOH)₂]₃ molecules in smaller aggregates and all types of aggregates were calculated. One can see that over the whole concentration range, from 0.01 to 10 g/dm³, aqueous solutions of C₆₀[=C(COOH)₂]₃ are characterized by sub-micro-heterogeneous behavior (because second-type aggregates with the linear dimensions – hundreds of nm are formed in all solutions). Additionally, the most concentrated solution (C = 10 g/dm³) is characterized by micro-heterogeneous or colloid behavior (because third-type aggregates with the linear dimensions on the order of µm – are formed). In order to describe or explain such behavior, a stepwise aggregation model was invoked.