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 40.3: Vortrag
Mittwoch, 14. März 2018, 10:15–10:30, C 264
Beyond the Navier-de Gennes Paradigm: Slip Inhibition on Ideal Substrates — Mark Ilton1,2, Thomas Salez3,4, Paul Fowler1,5, Marco Rivetti5, Mohammed Aly6, Michael Benzaquen4,7, Joshua McGraw1,6, 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.