Structure and thermodynamics of colloid-polymer mixtures: A macromolecular approach

¹ Physik-Department, Technische Universität München - 85747 Garching, Germany
² Departments of Materials Science & Engineering and Chemistry, University of Illinois Urbana, IL 61801, USA

Received: 12 April 2000
Accepted: 31 July 2000

Abstract

The change of the structure of concentrated colloidal suspensions upon addition of non-adsorbing polymer is studied within a two-component, Ornstein-Zernicke–based liquid state approach. The polymers' conformational degrees of freedom are considered and excluded volume is enforced at the segment level. The polymer correlation hole, depletion layer, and excess chemical potentials are described in agreement with polymer physics theory in contrast to models treating the macromolecules as effective spheres. Known depletion attraction effects are recovered for low particle density, while at higher densities novel many-body effects emerge which become dominant for large polymers.