Dresden 2009 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 39: POSTERS Colloids and Liquids

CPP 39.21: Poster

Thursday, March 26, 2009, 17:00–19:30, P3

Integral equations study of the depletion interaction between large colloids and a planar wall — Martin Oettel and •Vitalie Botan — Johannes-Gutenberg-Universität Mainz, Mainz, Germany

The integral equation theory, which is based on the full set of coupled inhomogeneous Ornstein-Zernike integral equations, has been developed for studying the depletion forces in colloidal suspensions containing a binary mixture of spheres close to a planar wall. Recent simulations pointed to a lack of sufficient theoretical understanding of the depletion force in hard systems with large asymmetry [1]. Our investigations of the wall-sphere depletion force in a purely hard system seem to be in good agreement with the recent Monte-Carlo simulation and density functional studies as well as predictions from morphological theory[2], which offers better insight into the regime of large asymmetry. The hard-sphere model captures the essence of the depletion phenomenon and can be mimicked experimentally by suitable choices of colloidal solutions [3]. However, a quantitative comparison between theory and experiment only appears possible if residual interactions are taken into account. We discuss the influence of effective electrostatic interactions among both species and the wall as well as the effect of gravity and tweezer forces in a model TIRM setup [4].

[1] A. R. Herring et al., Phys. Rev. Lett. 97 (2006), 148302.

[2] P.-M. König et al., Phys. Rev. Lett. 93 (2004), 160601.

[3] A. D. Dinsmore et al., Phys. Rev. Lett. 80 (1998), 409.

[4] D. Kleshchanok et al., J. Phys.: Cond. Matter 20 (2008), 073101.