Confinement effect on thermodynamic and structural properties of water in hydrophilic mesoporous silica

The adsorption of water on porous silica surfaces at 300 K, has been qualitatively reproduced by Grand Canonical Monte Carlo simulations (GCMC) without any adjustment of adsorbate/substrate potential parameter. The simulated adsorption isotherm and isosteric differential enthalpy of adsorption compare well to experimental data for Vycor, showing the ability of the model in describing hydrophilic properties of silica surfaces. The analysis of fluid structure in the mesoporous glass gives detailed insights into confinement and disorder effects on water adsorbed on the hydrophilic surface of a porous glass. It is shown that hydrophilic properties are not simply related to surface hydroxyl density but are also related to local structure of the silica surface.