Study of the water-oil interfacial activity of amino-modified graphene oxide

Abstract

The interfacial properties of Graphene oxide (GO) based materials have been widely studied in emulsification processes. The 2D chemical structure and high reactivity of Graphene Oxide (GO) allows the properties modification as wettability and dispersibility. Furthermore, the functionalized GO has been tested as a surfactant agent; however, little or nothing is known about its mechanism of action. Here, we investigated the interfacial activity of amine-modified GO in a water-toluene system. To consider the effect of the aliphatic chain length, GO was functionalized by amidation reaction and nucleophilic substitutions with n-propylamine (GO@3 C) and n-dodecylamine (GO@12 C). The covalent functionalization of GO was confirmed by FTIR spectroscopy, Raman spectroscopy, XPS spectroscopy, XRD and their morphology were observed by Scanning Electron microscopy. Results showed that the chemical modification of GO with n-alkylamines can decrease the Interfacial Tension (IFT) of the water-toluene system as the nanomaterial concentration increase, like a molecular surfactant that obey the Traube´s rule. Wettability of the materials it was also determined by the sessile drop method, revealing that the GO hydrophobicity increases as the length of the aliphatic chain becomes longer. Characteristics of the emulsion droplets were determined by micrograph analysis, and it was revealed that the diameter size, stability, and kind of emulsion can be changed depending on the type of GO functionalization.