A green route to stable aqueous dispersions of fullerene C60 through plasma processing

Fullerenes are promising nanomaterials, due to their biological, physical, photochemical, and electrical properties. However, their negligible solubility in water represents a limit to their extensive use. In this work, we propose a timesaving, green and dry chemistry approach, based on O2 low pressure plasma treatment, to enhance the dispersion of C60 in water. For the first time this kind of process is investigated to modify the C60 surface with polar oxygenated moieties and to fully characterize their water dispersions. The effect of plasma power and treatment time on the chemical composition and structure of fullerene powders, as well as on their dispersibility in water was investigated. XPS analyses on powders highlighted the presence of polar groups at the surface of plasma treated C60, even in higher amount on their dried water suspensions. On the other hand, XRD evidenced, an overall preservation of C60 cages. The enhancement of C60 dispersibility in water was supported by UV-Vis spectroscopy analysis. The obtained C60 dispersions were stable at least over a period of 15 days. Particles size (-220-250 nm), polydispersity index (-0.15) and zeta potential (--40 mV) of the plasma-modified C60 dispersions were assessed via DLS and ELS confirming the stability at different pH and ionic strength. The present work expands the knowledge of fullerenes processing for the preparation of stable aqueous C60 dispersions.