Preparation of stable aqueous dispersions of carbon nano-onions via supramolecular crown ether-ammonium interactions with aminated biocompatible polymers

We explore the possibility of using crown ether/ammonium interactions for the dispersion of carbon nano onions (CNOs) in water using biocompatible polymers. Pristine CNOs were functionalized by reaction of diazotized 4-aminobenzo-18-crown-6 and characterized by Raman and FTIR spectroscopies, thermogravimetric analysis and HRTEM. In the presence of biocompatible polymers containing pendant amino groups (aminated carboxymethyl cellulose and poly-L-lysine) the modified CNOs formed stable dispersions in water at acidic pH. In particular, the dispersion of modified CNOs in aminated carboxymethyl cellulose at pH 4 was stable after several months at room temperature. Precipitation of the modified CNOs under alkaline conditions and in the presence of excess K+ indicates that the ammonium/crown ether interactions are the major driving force in the formation of these dispersions. The method opens the way for the preparation of stable dispersions of carbon nanomaterials in water with several applications. (C) 2018 Elsevier B.V. All rights reserved.