Adsorption of graphene oxide at the oil-water interface: effects of concentration and temperature

As a two-dimensional material, graphene oxides (GOs) have attracted much attention due to their interfacial activity, easy functionalization, simple preparation, among others. Recently, some work demonstrated the amphiphilicity of GOs at the oil-water interface. Considering that an analysis of the adsorption behaviors of GOs at the interface is crucial to understand the amphiphilicity of GOs, we employ molecular dynamic method to explore the effect of concentration and temperature on the adsorption of GOs at the decane-water interface. The results show that the GOs adsorb at the interface with their surface parallel to the interface. With concentration increasing, the configuration of GOs changes from tiled form to stacks. At higher concentration, the GOs even are perpendicular to the interface. The transition of configuration of GOs at the interface induces a non-linear variation of interface tension, which we think is dominated by the hydrogen bonding at the GOs. In addition, with temperature rising, the interfacial tension decreases obviously because the arrangement and assembly of GOs at the interface is accelerated.