Depletion interactions and fluid-solid equilibrium in emulsions

Silicon-oil-in-water emulsions stabilized with sodium dodecylsulfate (SDS), have been studied. They exhibit practically no coalescence, whereas for high surfactant concentrations a ``creaming'' of the emulsion is observed. We demonstrate that this behavior is related to a fluid-solid phase transition due to an attractive interaction induced by the depletion of SDS micelles. A simple model for the fluid-solid transition is proposed, in quantitative agreement with experiment.