Fullerene C70 organohydrosols in water – dimethyl sulfoxide solutions

Hydrosols and aqueous suspensions of fullerenes have been studied by many research groups. In contrast, their colloid stability in the presence of organic solvent additives has been virtually unstudied. Meanwhile, the effect of adsorbable organic molecules on colloidal particles may resemble the effect of organic substances in biomedical and environmental studies. We have recently shown that colloidal solutions of C60 and C70 in DMSO can be easily prepared without the use of ultrasound. Now we study the properties of organohydrosols obtained by diluting these solutions with water. Fullerene colloids were characterized in DMSO and 1: 1 (by volume) DMSO–water binary mixture (52.4 mass. % DMSO) by dynamic light scattering, UV–visible spectroscopy, and TEM. The time evolution of the properties was investigated. While the UV–visible spectrum of C70 in entire DMSO smooths out over time, the characteristic bands in 52.4 mass. % DMSO remain even after six months. Coagulation of the negatively charged colloidal particles of C70 in 22.0 mass. % DMSO by inorganic salts was studied. The ratio of the CCC−1 values for Na+ (or K+), Ba2+, and La3+ is 1: 31: 836. At higher concentration of La(NO3)3, overcharging of the colloidal particles takes place. The data were discussed using the DLVO approach.