Berlin 2015 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 46: P11: Wetting, Micro and Nano Fluidics
CPP 46.3: Poster
Mittwoch, 18. März 2015, 10:00–13:00, Poster A
Relaxation of Surface Perturbations in Thin Liquid Films as a Probe of Liquid/Substrate Interactions — •Marco Rivetti1, Christine Linne1, Paul Fowler1,2, Joshua D. McGraw2, Thomas Salez3, Michael Benzaquen3, Elie Raphaël3, Kari Dalnoki-Veress2,3, and Oliver Bäumchen1 — 1Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen, Germany — 2Department of Physics & Astronomy, McMaster University, Hamilton, Canada — 3PCT Lab, UMR CNRS 7083 Gulliver, ESPCI ParisTech, PSL Research University, Paris, France
Perturbations of the free surface of a thin liquid film relax due to capillary forces. Flow is driven by local curvature gradients of the surface and resisted by the liquid's viscosity. For an initial non-equilibrium profile given by a step geometry, capillary leveling is shown to result in self-similar profiles. We find an excellent agreement between experimental profiles, as obtained from atomic force microscopy data, and numerical calculations. For liquid films supported by rigid substrates and in the presence of a no-slip boundary condition, this system provides a precise nano-rheological probe of the capillary velocity. For flows on small length scales, however, the interactions of liquid molecules with the substrate at the solid/liquid interface become important. We show that the capillary levelling is sensitive to the slip boundary condition at the solid/liquid interface. Thin film models comprising hydrodynamic slip enable a quantification of the slip length. Aside from friction, energy can also be dissipated through the elastic deformation of the substrate, which we will discuss in detail.