Polydispersity and osmotic pressure of stable ordered colloidal dispersions

Abstract

An expression is obtained from a simple model for the effect of polydispersity on the equation of state of an ordered electrostatically-stabilized colloidal dispersion. Comparison with cell theory and computer simulation confirm the model's validity in the region where repulsive forces dominate. The predicted increase in osmotic pressure is less pronounced the thicker the Debye–Hückel double-layer. Implications for the position of the order–disorder transition are considered.