Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 16: Poster: Colloids and Complex Liquids
CPP 16.11: Poster
Dienstag, 27. März 2012, 18:15–20:45, Poster A
Trapping colloids via critical Casimir forces — •Matthias Tröndle1,2, Andrea Gambassi3, Ludger Harnau1,2, and Siegfried Dietrich1,2 — 1Max-Planck-Institut für Intelligente Systeme, Stuttgart, Germany — 2Universität Stuttgart, Germany — 3SISSA - International School for Advanced Studies and INFN, Trieste, Italy
Colloids opposite to substrates patterned with stripes of different chemical boundary conditions experience normal and lateral critical Casimir forces. Upon approaching the critical point of the solvent, this generates laterally confining potentials for the colloids. The strength of these trapping potentials is reversibly tunable by temperature changes. Experimental measurements for colloidal particles immersed in a binary liquid mixture of water and 2,6-lutidine close to the critical demixing point agree with the corresponding theoretical predictions [1,2]. It turns out that critical Casimir forces are a sensitive probe to the details of the geometry of the substrate pattern. A suitable choice of chemical stripes forming the pattern may even lead to levitation of colloids at a stable distance from the substrate due to the critical Casimir effect [3].
[1] M. Tröndle, O. Zvyagolskaya, A. Gambassi, D. Vogt, L. Harnau, C. Bechinger, and S. Dietrich, Mol. Phys. 109, 1169 (2011). [2] M. Tröndle, S. Kondrat, A. Gambassi, L. Harnau, and S. Dietrich, EPL 88, 40004 (2009). [4] M. Tröndle, S. Kondrat, A. Gambassi, L. Harnau, and S. Dietrich, J. Chem. Phys. 133, 074702 (2010).