Excluded volume effects in the stabilization of colloids by polymers

Abstract

A self‐avoiding walk on a lattice, confined between two planes, is examined as a model of the stabilization of a colloidal system by adsorbed polymer. If the walk interacts with neither plane, there is a repulsive force on the planes due to the decrease in the volume of configuration space available to the walk. This effect is larger for a self‐avoiding walk than for a random walk. If the walk interacts with only one of the planes, with an attractive potential, there is a decrease in the magnitude of the stabilizing effect as the temperature decreases, but the force on the planes remains repulsive. If the walk interacts with both planes, with an attractive potential, there is a stabilizing effect at high temperatures but a destabilization (sensitized flocculation) at low temperatures.