Molecular Dynamics Simulation of Water-Acetonitrile Mixtures in a Silica Slit

Molecular dynamics simulations of aqueous acetonitrile confined in a planar silica slit are presented. It is found, in agreement with experimental observations, that a thin layer of water that excludes acetonitrile is in contact with the hydrophilic silica surface. The organization of the fluid-silica interfacial region is described for fluids with the fraction of water molecules in the system varying from 0 to 1 at 298 K. The width of the slit is set so that the density of the fluid in the central region of the slit is close to the density of the liquid for the temperature and composition of the mixture.