On the gel layer interpretation of anomalous viscosity of colloidal silica dispersions

Abstract

The anomalous viscosity of colloidal dispersions of silica has been known and studied for a long time. Several different mechanisms have been proposed to explain it, related to the electrical double layer, hydration layer, and porous/gel layer at the silica-water interface. However, it is still not entirely clear which mechanism is actually operative. Here, based on measurements of viscosity dependence on the concentration of indifferent electrolyte in highly diluted colloidal silica systems and its interpretation using the well-known Einstein equation, the concept of a swellable polyelectrolyte gel layer is corroborated.