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DY: Fachverband Dynamik und Statistische Physik

DY 39: Wetting, Microfluidics and Confined Liquids I (joint session CPP/DY)

DY 39.3: Vortrag

Mittwoch, 14. März 2018, 10:15–10:30, C 264

Beyond the Navier-de Gennes Paradigm: Slip Inhibition on Ideal Substrates — Mark Ilton^1,2, Thomas Salez^3,4, Paul Fowler^1,5, Marco Rivetti⁵, Mohammed Aly⁶, Michael Benzaquen^4,7, Joshua McGraw^1,6, Elie Raphael⁴, Kari Dalnoki-Veress¹, and •Oliver Bäumchen⁵ — ¹McMaster University, Hamilton, Canada — ²University of Massachusetts, Amherst, MA, USA — ³Univ. Bordeaux, Talence, France — ⁴ESPCI Paris, Paris, France — ⁵Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany — ⁶Ecole Normale Supérieure, Paris, France — ⁷Ecole Polytechnique, Palaiseau Cedex, France

Hydrodynamic slip of a liquid at a solid surface governs liquid transport at small scales. For polymeric liquids, de Gennes predicted that the Navier boundary condition together with the theory of polymer dynamics imply extraordinarily large slip for entangled polymer melts on ideal surfaces; this Navier-de Gennes paradigm was confirmed using dewetting experiments on ultra-smooth, low-energy substrates. Here, we use capillary leveling of polymeric films on these same substrates to measure the slip length from a robust one-parameter fit to a lubrication model. We show that at the low shear rates involved in leveling experiments, the employed substrates can no longer be considered ideal. The data is instead consistent with physical adsorption of polymer chains at the solid/liquid interface. We extend the Navier-de Gennes description using one additional parameter, namely the density of physically adsorbed chains per unit surface. The resulting model is found to be in excellent agreement with the experimental observations.