The internal structure of layered colloidal particles determined with SANS

Abstract

Small-angle neutron scattering measurements at various contrasts were performed on dilute colloidal silica dispersions in order to resolve the internal structure of the particles. The particles were prepared by outgrowth of a commercially available silica core, followed by an esterification of the surface silanol groups with stearyl alcohol. Variation of the scattering contrast was achieved by using mixtures of 1H12- and 2H12-cyclohexane as dispersing medium. The scattering data were interpreted as originating from a polydisperse system of spherical three-layer particles. Model parameters were optimized sequentially, applying an increasing number of constraints. Good agreement between experimental and calculated scattering curves is obtained, even at higher K values and low contrasts. In comparison with other particles in the same size range, these silica particles represent a very suitable model system for small-angle scattering experiments at higher volume fractions.