Structure and thermodynamics of colloid-polymer mixtures: A macromolecularapproach

The change of the structure of concentrated colloidal suspensions upon addi tion of non-adsorbing polymer is studied within a two-component, Ornstein-Z ernicke-based liquid state approach. The polymers' conformational degrees o f freedom are considered and excluded volume is enforced at the segment lev el. The polymer correlation hole, depletion layer, and excess chemical pote ntials are described in agreement with polymer physics theory in contrast t o 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 po lymers.