Microscopic theory of solvent mediated long range forces: influence of wetting

TL;DR

This paper develops a density functional theory to describe long-range solvent-mediated forces between large particles, accounting for wetting and critical fluctuations, with applications to models like polymer solutions.

Contribution

It introduces a general density functional approach that captures wetting effects and critical fluctuations in solvent-mediated forces between particles.

Findings

Long-range attractive potentials near the binodal

Wetting significantly influences particle interactions

Applicable to models like the Gaussian core model

Abstract

We show that a general density functional approach for calculating the force between two big particles immersed in a solvent of smaller ones can describe systems that exhibit fluid-fluid phase separation: the theory captures effects of strong adsorption (wetting) and of critical fluctuations in the solvent. We illustrate the approach for the Gaussian core model, a simple model of a polymer mixture in solution and find extremely attractive, long ranged solvent mediated potentials between the big particles for state points lying close to the binodal, on the side where the solvent is poor in the species which is favoured by the big particles.