Berlin 2015 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 35: Complex Fluids and Soft Matter - Part I (joint session DY/ CPP / BP)

DY 35.3: Talk

Wednesday, March 18, 2015, 15:30–15:45, BH-N 333

Binary mixtures of hard rod–like colloids: mesoscopic equilibrium theory and shear-driven instabilities — •Rodrigo Lugo Frias and Sabine Klapp — Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany

Mixtures of rod–like particles occur in a wide range of biological contexts and technological applications, and their equilibrium phase behavior has been intensely studied in recent years. Here we investigate a binary mixture of rod–like colloidal particles driven out of equilibrium by means of a steady shear flow (Couette geometry).

Using classical density functional theory (DFT), we first derive a mesoscopic free energy functional for a mixture of hard spherocylinders with different length–to–length ratio in terms of tensorial order parameters that describe their alignment. The resulting free energy displays a strong dependence on the microscopical properties of the system. Based on the equilibrium analysis, we then discuss the dynamical behavior of the mixture using a natural extension of the mesoscopic Doi–Hess theory. In particular we analyze the orientational dynamics under shear for varying shear rate, concentration and aspect ratio.

[1] F. Tardani, L. Gentile, G. A. Ranieri and C. La Mesa, J. Phys. Chem. C, 117, 8556 (2013).
[2] S. Hess, Z.Naturforsch. A 31a, 1034 (1976). M. Doi, J.Polym. Sci., Polym. Phys. Ed. 19, 229 (1981).
[3] R.  Lugo-Frias and S. H. L. Klapp, in preparation (2015).