Graphene oxide-induced structural morphology and colloidal interaction at water–oil interface

Abstract

Adsorption of amphiphilic monolayer graphene oxides (GOs) at oil–water interfaces can modify the interfacial structure and morphology, and in turn, influence their aggregating interactions and packing arrangement. A microscopic understanding of adsorption structures and interaction mechanisms for nanoscale GOs with varied chemical compositions at the interfaces can guide and improve the GO-related material preparation and micro-emulsification processes. Herein, all-atom molecular dynamics simulations were conducted for the structural morphologies and residing organizations of multiple GO nanosheets at the water-cyclohexane interface. The colloidal interaction was simulated as the potential of mean forces (PMF) between GO nanosheets at the interface. For the first time, the interfacial structural morphologies were revealed and correlated with the GO chemical compositions. GO nanosheets with more edge carboxyl groups, lower oxidation degrees, or lower hydroxyl proportion can lead to more uniform or homogeneous GOs packing, corresponding to weaker interface fluctuation or distortion. The PMF-based interactions can be applied to explain the GOs contacting performances at the interface, wherein the interfacial water plays a controlling role in regulating the GO interactions. Our simulation study provides new insights into the GO-induced liquid–liquid interface behavior.