An Integral Equation Study of the Hydrophobic Interaction between Graphene Plates

The hydrophobic association of two parallel graphene sheets is studied using the 3D-RISM HNC integral equations with several theoretical methods for the solvent distribution functions. The potential of mean force is calculated to study the effects of the aqueous solvent models and methods on the plates as a function of distance. The results of several integral equations (IE) are compared to MD simulations for the same model. The 3D-IEs are able to qualitatively reproduce the nature of the solvent effects on the potential of mean force but not quantitatively. The local minima in the potential of mean force occur at distances allowing well defined layers of solvent between the plates but are not coincident with those found in simulation of the same potential regardless of the theoretical methods tested here. The dewetting or drying transition between the plates is generally incorrectly dependent on steric effects with these methods even for very hydrophobic systems without solute-solvent attractions, in contradiction with simulation.