Eur. Phys. J. E (2012) 35: 60
https://doi.org/10.1140/epje/i2012-12060-7

Regular Article

Shear-affected depletion interaction

¹ Forschungszentrum Jülich, ICS-3 - Soft Matter, Jülich, Germany
² Van ’t Hoff Laboratory for Physical and Colloid Chemistry - Debye Research Institute, Utrecht University, Utrecht, The Netherlands

^* e-mail: e.july@fz-juelich.de
^** e-mail: p.lang@fz-juelich.de

Received: 17 January 2012
Revised: 8 May 2012
Accepted: 20 June 2012
Published online: 19 July 2012

Abstract

We investigate the influence of flow fields on the strength of the depletion interaction caused by disc-shaped depletants. At low mass concentration of discs, it is possible to continuously decrease the depth of the depletion potential by increasing the applied shear rate until the depletion force is not perceivable experimentally. Above a threshold in the platelet mass concentration, the depletion potential can no longer be affected by flow in the accessible range of shear rates. While the observed decrease of depletion strength at low depletant concentration may be ascribed to flow alignment of the discs, it is not clear why the influence of flow is vanishing at high concentrations. In order to observe these effects, a modification of the established total internal reflexion microscopy (TIRM) technique is be implemented. We show the suitability of these modifications to measure particle-wall interaction potentials under non-equilibrium conditions for systems where particles are exposed to a shear.