Influence of non-adsorbing polymer on the formation of colloidal crystals

Abstract

We studied the effect of non-adsorbing polymer on the crystallization phenomena of colloidal dispersions. The experiments have been performed on dispersions of monodisperse stearyl silica spheres in cyclohexane to which polystyrene or poly(dimethyl siloxane) was added. For all polymers used the behaviour was roughly similar. The addition of free polymer has a pronounced effect on the crystallization phenomena. The rate of crystallization increases dramatically. Besides ordering on top of the sediment, it turned out to be possible to induce crystallization throughout the entire sample just around the minimum concentration required for phase separation into a colloid-rich and a polymer-rich phase.