Dresden 2014 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 40: Colloids and Complex Liquids III
CPP 40.2: Talk
Thursday, April 3, 2014, 11:30–11:45, ZEU 260
Alignment of cylindrical colloids induced by critical Casimir torques — •Marcel Labbé-Laurent1,2, Matthias Tröndle1,2, Ludger Harnau1,2, and Siegfried Dietrich1,2 — 1Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, 70569 Stuttgart — 2IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart
Critical fluctuations in simple fluids or binary liquid mixtures give rise to forces acting on immersed colloidal particles. These Casimir-like forces are attractive or repulsive depending on the chemical surface properties [1]. Recent experiments have demonstrated a fluctuation-induced lateral trapping of spherical colloidal particles immersed in a binary liquid mixture near its critical demixing point and exposed to chemically patterned substrates [2].
Inspired by these experiments, we study the critical Casimir effect for elongated colloids of cylindrical shape. When the colloidal particles are close to a chemically structured substrate, a critical Casimir torque acting on the colloids emerges. Our analysis indicates that critical Casimir interactions are capable to achieve well-defined, reversible alignments both of chemically homogeneous and of Janus cylinders [3].
[1] C. Hertlein, L. Helden, A. Gambassi, S. Dietrich, and C. Bechinger, Nature 451, 172 (2008)
[2] M. Tröndle, O. Zvyagolskaya, A. Gambassi, D. Vogt, L. Harnau, C. Bechinger, and S. Dietrich, Mol. Phys. 109, 1169 (2011)
[3] M. Labbé-Laurent, M. Tröndle, L. Harnau, S. Dietrich, preprint; arXiv:1311.3814 (2013)