(631c) Molecular Dynamics Simulation of Amphiphilic Graphene Oxide As a Tunable Colloidal Surfactant in Oil/Water Mixtures

Recently, the amphiphilic nature of graphene oxide (GO) has been shown to provide a significant advantage for its use as an efficient colloidal stabilizer and emulsifier in oil/water mixtures. The GO emulsification can be tuned by factors such as degree of oxidation, size of the graphene sheets, and pH level of the medium. In spite of several reports pertaining to GO as a tunable surfactant, a deep understanding of the emulsification process is still missing. Hereon, we study the effects of above-mentioned factors on the GO amphiphilicity using molecular dynamics (MD) simulation in BIOVIA Materials Studio software with COMPASS force field. A series of toluene/water/GO systems with varying GO sheet sizes, O/C ratios (surface oxygen densities), and pH levels are geometry-optimized. Then we run dynamics simulations using the NVT ensemble for 8 ns and analyze the equilibrated systems. The results of this study provide a more comprehensive picture of how to tune the GO emulsification for oil/water mixtures and the field of stimuli-responsive stabilizers, which are of great importance in crude oil extraction, recycling petroleum industry effluents, and pharmaceutical industries.