Eur. Phys. J. E (2016) 39: 115
https://doi.org/10.1140/epje/i2016-16115-5

Regular Article

Phase behaviour of colloids plus weakly adhesive polymers

¹ Laboratory of Physical Chemistry (SPC), Department of Chemical Engineering and Chemistry & Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Helix STO 2.49, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
² Van ’t Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry & Debye Institute, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
³ Physical Chemistry, Department of Chemistry, Lund University, P.O. Box 124, S-22100, Lund, Sweden

^* e-mail: r.tuinier@tue.nl

Received: 14 June 2016
Accepted: 7 November 2016
Published online: 30 November 2016

Abstract

The phase behaviour of a colloidal dispersion mediated by weakly adhesive polymers is considered. The polymers are depleted but are weakly adhesive and hence comprise a non-zero polymer concentration at the colloid’s surface, in contrast to the classical assumption in depletion theories involving a zero polymer concentration at the surface. The theory is composed of a generalized free-volume theory for colloid-polymer mixtures and a self-consistent mean-field theory for polymers at surfaces. It is found that the weak adhesion of the polymers shifts the phase stability of the colloid-polymer mixtures to higher polymer concentrations as compared to assuming a full depletion effect. The predicted phase diagrams employing the new theory are consistent with experiments on mixtures of silica spheres coated with stearyl alcohol and polydimethylsiloxane in cyclohexane and with Monte Carlo simulation results.