Entropy Driven Phase Separation in Binary Emulsions

Abstract

We have studied experimentally phase separation in binary mixtures comprised of nearly monodisperse emulsion droplets of two different sizes. For three values of ξ, where $\xi <1\mathrm{}$ is the size ratio, we have determined phase diagrams and find that segregation occurs for $\xi \le 0.30\pm 0.02$. The phase boundaries are strongly dependent on ξ, and phase-separated samples show nearly complete segregation of the two components, as a result of the osmotic depletion effect which drives the phase segregation. Our results agree qualitatively with recent model calculations.