Tunable dispersibility and wettability of graphene oxide through one-pot functionalization and reduction

Hypothesis: Surface functionalization is an effective method to tune the wettability and dispersibility of graphene oxide (GO) nanosheets, but functionalization methods often require long reaction times and expensive reagents. To meet this GO processing need, we propose a quick, industrially scalable GO functionalization scheme based upon Fischer esterification and epoxide ring-opening reactions; we expect this method to yield hydrophobic graphene with tuned wettability and dispersibility properties through the attachment of various alkyl groups. Experiment: N-pentyl and t-butyl groups were grafted onto GO in a one-pot functionalization and reduction scheme and chemical functionalization was confirmed by various techniques. Subsequently, the wettability of the functionalized GO was investigated through contact angle measurements and the dispersibility of GO in various solvents was observed. Findings: The contact angle of n-pentyl functionalized GO increased to 134.0 degrees, a value comparable or superior to those achieved for functionalized GO in the literature. Furthermore, dispersibility studies showed that functionalized GO had distinct affinities for organic solvents, with t-butyl functionalized GO being highly dispersible in chloroform and n-pentyl GO being highly dispersible in toluene. We propose that this functionalization and reduction method could be successfully applied on the industrial scale to engineer reduced graphene oxide with tuned dispersibility and wettability properties. (C) 2019 Elsevier Inc. All rights reserved.