Entropically Driven Surface Phase Separation in Binary Colloidal Mixtures

P. D. Kaplan; J. L. Rouke; A. G. Yodh; D. J. Pine

doi:10.1103/PhysRevLett.72.582

Entropically Driven Surface Phase Separation in Binary Colloidal Mixtures

P. D. Kaplan, J. L. Rouke, A. G. Yodh, and D. J. Pine

Phys. Rev. Lett. 72, 582 – Published 24 January 1994

Abstract

We investigate the phase diagram of mixtures of charge stabilized polystyrene spheres of two different sizes in the hard-sphere limit. We observe bulk phase separation into two disordered phases and find a new ordered phase located on the cell walls. The ordered phase occurs at volume fractions as low as 0.2, much less than the value of 0.49 for hard-sphere freezing in monodisperse suspensions, and is qualitatively explained with simple geometric arguments.