Formation of micelle-decorated colloidal silica by adsorption of nonionic surfactant

The structure of the adsorbed layer of a nonionic surfactant on small colloidal silica beads in water at high pH is revisited. The adsorption isotherm was constructed by centrifugation and subsequent spectroscopic determination of the concentration of nonadsorbed surfactant in the supernatant. The shape of the surfactant-silica complexes was measured by small-angle neutron scattering in dilute solutions. External contrast variation was used to enhance scattering from the silica and the surfactant, respectively. Spectra are analyzed by comparison to results of numerical simulations of micelle-decorated silica beads. Very good agreement between experimental data and simulations is found.