Regensburg 2013 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 34: Poster: Wetting, Micro and Nano Fluidics
CPP 34.20: Poster
Wednesday, March 13, 2013, 16:30–18:30, Poster C
Capillary Levelling of Stepped Polymer Films - A Nanofluidic Probe of the Slip Boundary Condition — •Oliver Bäumchen1, Thomas Salez2, Joshua D. McGraw1, Michael Benzaquen2, Paul Fowler1, Elie Raphaël2, and Kari Dalnoki-Veress1 — 1Department of Physics & Astronomy and the Brockhouse Institute for Materials Research, McMaster University, Hamilton, ON, Canada, L8S 4M1 — 2Laboratoire de Physico-Chimie Theorique, UMR CNRS Gulliver 7083, ESPCI, Paris, France
For flows on small length scales, the hydrodynamic boundary condition of a liquid at a solid surface plays an enormous role. In recent years much has been learned about this slip boundary condition from flows that are driven by internal, capillary, forces such as dewetting of thin liquid films. For the case of dewetting, holes in the film grow, driven by exposing the underlying substrate. Here, we present the opposite approach: We show that the capillary levelling of initially curved surfaces, in our case stepped polymer films, is sensitive to the nano-rheological properties of the liquid [1] and the slip boundary condition at the buried liquid/substrate interface. A thin film model which includes the hydrodynamic boundary condition enables us to quantify slip at the buried interface and to extract its dependence on the molecular weight of the polymer.
[1] J.D. McGraw, T. Salez, O. Bäumchen, E. Raphaël, and K. Dalnoki-Veress, Physical Review Letters 109, 128303 (2012).