Eco-friendly amidation of oxidized carbon black by dry ball milling†

An unprecedented amidation of oxidized carbon black (oCB) by a mechanochemical approach is reported. The reaction proceeds in the presence of octadecylamine (ODA) in a short time, providing the corresponding adduct (oCB/ODA) with a high degree of functionalization. Hummers and ball milling procedures were used to obtain oxidized carbon black in solution and solvent-free conditions, respectively. Although the oxidation procedure used for oCB synthesis can deeply affect the degree of amidation because of the different nature of the functional groups on the carbon surface, the resulting powders were both functionalized with amine. The corresponding adducts showed a strong inversion of polarity, going from the high dispersibility in the water solution of the starting material to the high hydrophobic behaviour due to the alkyl chains bonded on the surface. Since the mechanochemical approach respects important green metrics, the procedure is highly sustainable.