Molecular dynamics analysis of the influence of Coulomb and van der Waals interactions on the work of adhesion at the solid-liquid interface

We investigated the solid-liquid work of adhesion of water on a model silica surface by molecular dynamics simulations, where a methodology previously developed to determine the work of adhesion through thermodynamic integration was extended to a system with long-range electrostatic interactions between solid and liquid. In agreement with previous studies, the work of adhesion increased when the magnitude of the surface polarity was increased. On the other hand, we found that when comparing two systems with and without solid-liquid electrostatic interactions, which were set to have approximately the same total solid-liquid interfacial energy, former had a significantly smaller work of adhesion and a broader distribution in the interfacial energies, which has not been previously reported in detail. This was explained by the entropy contribution to the adhesion free energy; i.e., the former with a broader energy distribution had a larger interfacial entropy than the latter. While the entropy contribution to...