Pair interaction and phase separation in mixtures of colloids and excluded volume polymers

Abstract

The interactions in polymer–colloid mixtures and their phase stability are calculated using the adsorption method. Starting from appropriate expressions for the correlation length and the osmotic pressure of a polymer solution in the excluded volume interaction limit, this method allows computation of the potential between two plates, two spheres and between a sphere and a plate. The results are in close agreement with computer simulation results. Extended to a many body system of colloids and polymers, the same approach allows one to calculate the thermodynamic properties and phase behavior. Results are presented for the phase behavior of polymer–sphere and polymer–platelet mixtures. The agreement with experimental data is satisfactory and helps to better explain the polymer–colloid phase behavior.