The peculiar behavior of fullerene C60 in mixtures of 'good' and polar solvents: Colloidal particles in the toluene-methanol mixtures and some other systems

The state of C-60 in toluene-methanol mixtures and some other solvents was studied within the range of fullerene concentrations from 4 x 10(-7) to 4 x 10(-5) M. The variations in the particle size from ca. 200-500 to ca. 1 nm, as followed up using the dynamic light scattering (DLS) method, were compared with the UV-vis absorption spectra. The threshold composition of the mixed solvent, which corresponds to the disappearance of single C-60 molecules, depends on the fullerene concentration. In toluene-methanol systems, small amounts of large aggregates were detected via the DLS even under conditions of substantial predominance of single molecules. The examination of the fullerene in several other binary organic solvents reveals the specific features of the formation and behavior of the negatively charged colloidal particles. (C) 2016 Elsevier B.V. All rights reserved.