Berlin 2012 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 16: Poster: Colloids and Complex Liquids
CPP 16.19: Poster
Tuesday, March 27, 2012, 18:15–20:45, Poster A
Critical Casimir torques acting on cylindrical colloids and Janus particles — •Marcel Labbé-Laurent1,2, Matthias Tröndle1,2, Ludger Harnau1,2, and Siegfried Dietrich1,2 — 1Max-Planck-Institut für intelligente Systeme, Stuttgart, Germany — 2Universität Stuttgart, Germany
Critical fluctuations in fluids give rise to forces acting on immersed colloidal particles. These Casimir-like forces are attractive or repulsive depending on the chemical surface properties. Self-assembly of colloids opposite to structured surfaces, induced by the critical Casimir effect, is observed experimentally for colloidal particles immersed in a critical water-2,6-lutidine mixture and is in agreement with theory [1]. Asymmetrical particles experience a critical Casimir torque in the presence of varying boundary conditions. The strength and the direction of the torque depend on the particle shape. Rod-like and disc-like particles exhibit different self-orientation. Similarly, Janus-particles are subject to critical Casimir torques and self-orientate, which may be useful in view of current research or applications.
[1] M. Tröndle, O. Zvyagolskaya, A. Gambassi, D. Vogt, L. Harnau, C. Bechinger, and S. Dietrich, Mol. Phys. 109, 1169 (2011).