Surface Strain Effects on the Water-Graphene Interfacial and Confinement Behavior

We studied via molecular dynamics the link between the strain-driven hydration free-energy changes in the association process involving finite-size graphene surfaces, the resulting water graphene interfacial tension, and the combined effect of the surface strain and confinement on the thermodynamic response functions and the dynamics of confined water. We found that an in-plane biaxial tensile strain epsilon = 10% enhances significantly not only the water graphene hydrophobicity with respect to that of the unstrained counterpart but also the confinement effect on the thermodynamic response functions and slowing down of the dynamics of water over those of the corresponding bulk counterpart. The interfacial behavior of water in contact with strained-graphene plates resembles that observed for pp corrugated-plate configuration, as reported earlier [Chialvo et al. J. Phys. Chem. C 2013, 117, 23875], exibiting a significant enhancement of the fluid surface hydrophobicity and response functions relative to those of the unstrained surface. In contrast, the slowing down of the dynamics of the confined water does not show any differentiation with respect to the type of surface.