preprints.org > chemistry and materials science > physical chemistry > doi: 10.20944/preprints202310.0808.v1

Preprint Review Version 1 Preserved in Portico This version is not peer-reviewed

Version 1 : Received: 11 October 2023 / Approved: 11 October 2023 / Online: 13 October 2023 (02:53:07 CEST)

This review article is devoted to the colloidal properties of fullerene solutions. According to generally accepted understanding, all solvents in relations to fullerenes are divided into “good” (or “strong” or “high-solubility” ones), “poor” (usually polar) and “reactive”. Water occupies a special place, close to “poor” solvents. We have consistently considered and discussed the state of fullerenes in these systems. In "good", predominantly non-polar aromatic solvents and CS2, nonequilibrium dissolution methods lead to the formation of colloidal aggregates, whereas utilization of equilibrium methods results in the formation of molecular solutions. The latter, however, have some unusual properties; new results confirm previously expressed ideas about colloidal properties of these solutions. Both experimental and theoretical methods devoted to such systems are considered. In “poor” (polar) solvents, typical lyophobic colloidal systems appear. Both “bottom-up” and “top-down” methods of preparation are now well documented in the literature. However, some of these polar solvents dissolve fullerenes rather easily and with less energy consumption. In addition to N-methylpyrrolidin-2-one, which has been well studied for fullerenes, DMSO and DMF have now been described. These solvents can be considered a subset of poor solvents that have some features of being “reactive” at the expense of basic (“cationophilic”) properties. Room temperature ionic liquids are also used to dissolve fullerenes, but there is little experimental research. Hydrosols and aqueous suspensions of fullerenes are typical hydrophobic colloids that obey the Schulze–Hardy rule and other regularities in the presence of electrolytes. New experimental data confirm the previously obtained results. Organosols in acetonitrile and methanol are much less stable with respect to electrolytes; the difference in critical coagulation concentrations of electrolytes reaches two to three orders of magnitude. This allows us to conclude that there is an additional, so-called non-DLVO, stabilizing factor in the hydrosols. Accordingly, the value of the Hamaker constant of fullerene-fullerene interaction may be higher than that derived from coagulation data in water. Contrary to the mentioned “poor” polar solvents, the stability of fullerene sols in DMSO is even higher than in water. These results, as well as data obtained with DMF demonstrate strong solvation of fullerenes with basic solvents.

fullerenes; good and poor solvents; aggregate formations; organosols; hydrosols; coagulation by electrolytes; overcharging of colloidal particles; Hamaker constant

Chemistry and Materials Science, Physical Chemistry

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