Solvent Effects on Molecular Adsorption on Ag Surfaces: Polyvinylpyrrolidone Oligomers

The solution-phase adsorption of solutes on solid surfaces is important in a number of applications that are currently being researched. However, most theoretical approaches describing this phenomenon fall short of accurately describing the solution environment. Herein, we use classical molecular dynamics simulations based on an accurate many-body force field to quantify vacuum and solution-phase (ethylene glycol) adsorption free energies of polyvinylpyrrolidone (PVP) oligomers on Ag surfaces—a system studied experimentally for solution-phase nanocrystal growth. We find a favorable free-energy change when PVP adsorbs to Ag surfaces in the presence of solvent. However, the binding free energy for a PVP molecule in solution is significantly smaller than that for a PVP molecule in vacuum. In vacuum, the adsorbates lose considerable entropy upon adsorption to a solid surface because of a loss in their configurational degrees of freedom. In solution, adsorption entropies are a result of a solvent–solute exchan...