Interfacial structure of an H-bonding liquid confined into silica nanopore with surface silanols

Molecular computer simulation has been performed on liquid methanol confined into silica cylindrical pores with diameter D = 24 angstrom. It has been motivated by recent conclusions obtained from neutron scattering experiments in similar conditions of confinement. A central issue is the influence of H-bond interactions within the fluid and between the fluid and the pore surface on the local structure of the liquid. It relies on the use of a realistic atomic description of the porous silicate and the chemical nature of the surface. A description of the interfacial interactions and the spatial correlations has been achieved in terms of energy distribution functions and density radial distribution functions. It shows that surface silanols significantly affect the spatial arrangement of the interfacial methanol molecules, which occupy half the pore volume. In addition, the effects of the surface boundary conditions propagate into the entire volume through layering and orientation order. (C) 2005 Elsevier B.V. All rights reserved.