Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 13: Poster: Interfaces and Thin Films
CPP 13.34: Poster
Dienstag, 27. März 2012, 18:15–20:45, Poster A
Modelling surfactant covered films - thermodynamic reformulation and extension of the hydrodynamic evolution equations — •Uwe Thiele1, Andrew J. Archer1, and Plapp Mathis2 — 1Department of Mathematical Sciences, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK — 2Physique de la Matiere Condensee, Ecole Polytechnique, CNRS, 91128 Palaiseau, France
We propose several models that describe the dynamics of liquid films that are covered by a relatively large concentration of insoluble surfactant. First, we briefly review the ’classical’ hydrodynamic form of the coupled evolution equations for film height and surfactant concentration that are well established for small concentrations. Then we re-formulate the basic model as a gradient dynamics based on an underlying free energy functional that accounts for wettability and capillarity. Based on this re-formulation in the framework of non-equilibrium thermodynamics, we propose extensions of the basic hydrodynamic model that account for (i) nonlinear equations of state, (ii) surfactant-dependent wettability, (iii) surfactant phase transitions, and (iv) substrate-mediated condensation. In passing we discuss important differences to models found in the literature.
We acknowledge support by the EU (PITN-GA-2008-214919).