Molecular dynamics simulation of capillary evaporation of water adsorbed on hydrophilic nanopores.

Abstract

The coarse-grained non-equilibrium molecular dynamics simulations were performed to investigate the capillary evaporation of water adsorbed on hydrophilic nanopores. The ELBA water model was implemented. To assess the effect of hydrophilicity, three hydrophilic nanoporous thin films, which made of fixed water molecules, were modeled by tuning the interactions between water and pore wall molecules. Initially, equilibrium pore–filling state were obtained by canonical ensemble molecular dynamics simulations. Then, the evaporation processes into vacuum were performed by adopting the deletion boundary conditions for both ends of the rectangular parallelepiped simulation cell. The desorption rate shows almost constant within the capillary evaporation regime and did not clearly depends on the hydrophilicity. This could be attributed to the evaporated water molecule did not attracted by interaction from pore wall. The adsorbed water layer arises from higher hydrophilicity enhances the mass flux of condensed water in the pore.