Liquid separation by a graphene membrane

The behavior of liquids separated by a single graphene membrane has been studied with extensive molecular dynamics (MD) simulations at ambient conditions. With the help of appropriate empirical potentials, we have exploited two liquid phases forming distinct systems; say XGY, where G stands for graphene and X (Y) represents water (W), benzene (B), or acetonitrile (A). Our MD simulations revealed important changes in the wettability patterns of these liquids near the graphene surface. For instance, WGW exhibits strong density oscillations in a thin interfacial region with thickness of similar to 2.4 nm. In the case of BGB and AGA the oscillating-density interfacial region extends beyond similar to 3 nm and similar to 5 nm, respectively, under ambient conditions. More interestingly, our findings indicate that a liquid at one side of the graphene sheet can affect the degree of wetting on the other side, by means of dispersion interactions through the graphene membrane. These systems can offer a useful framework to understand the structural as well as thermodynamic properties of interfaces by considering a real two-dimensional substrate. (c) 2010 American Institute of Physics. [doi: 10.1063/1.3518507]