Polymer-mediated colloidal stability: on the transition between adsorption and depletion

Álvaro González García; Marjolijn M B Nagelkerke; Remco Tuinier; Mark Vis

doi:10.1016/j.cis.2019.102077

Polymer-mediated colloidal stability: on the transition between adsorption and depletion

Adv Colloid Interface Sci. 2020 Jan:275:102077. doi: 10.1016/j.cis.2019.102077. Epub 2019 Nov 21.

Authors

Álvaro González García¹, Marjolijn M B Nagelkerke¹, Remco Tuinier², Mark Vis³

Affiliations

¹ Van 't Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry & Debye Institute, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands; Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry & Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands.
² Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry & Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands; Van 't Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry & Debye Institute, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands. Electronic address: r.tuinier@tue.nl.
³ Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry & Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands.

PMID: 31816521
DOI: 10.1016/j.cis.2019.102077

Abstract

Addition of polymers to a colloidal dispersion modulates the interactions between the colloids. We briefly review the effects of positive and negative adsorption (also termed depletion). The effective colloid-polymer interactions sensitively affect the colloidal phase behavior. We present a theoretical framework to predict the phase behavior of colloid-polymer mixtures for varying affinities between colloid and polymer, leading to either positive or negative adsorption of polymer segments. For certain conditions, polymers are neither depleted nor adsorbed: the polymer concentration is essentially constant up to the colloidal surface, a condition which we term neutral adsorption. Near this condition, the calculated phase diagrams reveal a stable-unstable-restabilisation transition with increasing polymer concentration. Similar effects have been reported experimentally, for instance as a function of temperature [Feng et al., Nat. Mat., 2015, 14, 61-65], which may modulate the effective polymer-colloid affinity. Understanding how to achieve neutral adsorption opens up the possibility of preparing highly dense, yet stable, colloid-polymer mixtures.

Keywords: Adsorption; Bridging; Colloidal interaction; Colloid–polymer mixtures; Depletion; Phase behavior.

Publication types

Review