Regensburg 2013 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 44: Wetting, Micro- and Nanofluidics
CPP 44.6: Vortrag
Donnerstag, 14. März 2013, 16:30–16:45, H39
Self-Similarity and Energy Dissipation in Stepped Polymer Films — •Joshua D. McGraw1, Thomas Salez2, Oliver Bäumchen1, Elie Raphaël2, and Kari Dalnoki-Veress1 — 1Department of Physics & Astronomy and the Brockhouse Institute for Materials Research, McMaster University, Hamilton, ON, Canada — 2Laboratoire de Physico-Chimie Theorique, UMR CNRS Gulliver 7083, ESPCI, Paris, France
We have recently learned how to prepare polymer films whose only feature is a step in the height profile [1]. In the melt, Laplace pressure drives a flow that levels the topography, with the excess energy of the height step being dissipated by viscosity. It has been observed that the profiles are self-similar in time for a variety of molecular weights and geometries. Given the surface tension, this simple observation allows a precise measurement of the viscosity by comparison with numerical solutions [2] of the thin film equation. It is also possible to derive a master expression for the time dependence of the excess surface energy as a function of the material properties and film geometry. Thus, all geometries and molecular weights fall on a single temporal curve. The material parameter allowing this collapse is the capillary velocity: the ratio of the surface tension to the viscosity.
[1] McGraw et al., PRL (2012).
[2] Salez et al., EPJE (2012).