Structuring of colloidal silica nanoparticle suspensions near water–silica interfaces probed by specular neutron reflectivity

Abstract

Structuring of aqueous suspensions of colloidal silica nanoparticles near an isolated planar silica–water interface is studied by specular neutron reflectivity. The reflectivity data clearly show that the suspensions develop a damped, oscillatory concentration profile in the normal direction to the interface. The wavelengths of these oscillations agree well with those independently determined by direct force measurements in the slit-geometry. The reflectivity data further demonstrate that the oscillatory structure persists over several layers and that the first particle layer is separated from the interface by a particle-free region.