Solvation in nanoscale solvophobic confinement near liquid–gas phase coexistence

Abstract

We study using computer simulations the solvation dynamics of a solvophilic solute in a solvophobic nano-confinement placed in equilibrium bulk subcritical liquid near liquid–gas phase-coexistence. We find a bi-exponential solvent response inside the confinement as in the bulk. The solvation timescales are significantly shorter under strong confinement compared to the bulk timescale. This is for a low density fluid phase created via competition between drying effect by the solvophobic walls and the surface-mediated wetting by the solvophilic solute. The timescale increases linearly with slit separation to approach the bulk value. We rationalize our observations by simple hydrodynamic arguments.