Molecular dynamics simulation of water confined in a nanopore of amorphous silica

Molecular dynamics simulations are performed to study the transport and structural properties of water confined in a cylindrical silica nanopore. The pore wall is amorphous and mimics a typical mesoporous silica material. The diameters of silica pores studied are 4.75, 9.51, 20 and 25 angstrom. The self-diffusion of water calculated decreases with pore size and indicates much slower transport compared to the bulk phase. Strong adsorption of water to the silica wall is observed in the density profiles, indicating the hydrophilic nature of the wall. The hydrogen-bonding network is strongly affected by water-silica wall interaction. The average number of hydrogen bonds per water decreased with decreasing pore diameter.