Berlin 2018 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 40: Wetting, Microfluidics and Confined Liquids I (joint session CPP/DY)
CPP 40.4: Vortrag
Mittwoch, 14. März 2018, 10:30–10:45, C 264
Consistency condition for macro- and mesoscopic descriptions of contact line with surfactant — •Uwe Thiele1, Sarah Trinschek1, Jacco H. Snoeijer2, and Karin John3 — 1Institut für Theoretische Physik, Universität Münster, Wilhelm-Klemm-Str. 9, Münster — 2Physics of Fluids Group, Faculty of Science and Technology, University of Twente, Enschede — 3Laboratoire Interdisciplinaire de Physique, Université Grenoble-Alpes, CNRS
Consider a three-phase contact line where a liquid-gas interface meets a solid. For a simple liquid at equilibrium it is described on the macroscale by the Young-Dupré law relating the three interfacial energies to the equilibrium contact angle θe. On the mesoscale, it is modelled by a film-height-dependent wetting energy f(h). Macro- and mesoscale description are consistent if γ cosθe =γ+f(ha) where γ and ha are the liquid-gas interface energy and the thickness of the equilibrium adsorption layer, respectively.
Our contribution discusses the incorporation of insoluble surfactant. We derive the macro- and mesoscopic equilibrium models for spatially inhomogeneous states (consistent with the dynamic approach of [1,2]). Discussing the case of a static contact line with surfactant, we show that again there exists a consistency condition between macro- and mesoscopic descriptions. It imposes a particular dependence of the wetting energy on surfactant concentration. This is illustrated at a simple example. [1] U. Thiele, A. J. Archer and M. Plapp, Phys. Fluids 24, 102107 (2012). [2] U. Thiele, A. J. Archer and L. M. Pismen, Phys. Rev. Fluids 1, 083903 (2016).