Regensburg 2007 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 19: POSTER: Micro and Nano Fluidics
CPP 19.15: Poster
Wednesday, March 28, 2007, 16:00–18:30, Poster B
Fingering instability in entangled polymer films — •Julia Mainka1, Chiara Neto2, Oliver Bäumchen1, and Karin Jacobs1 — 1Saarland University, Experimental Physics, D-66041 Saarbrücken, Germany — 2Department of Applied Mathematics, Research School of Physical Sciences and Engineering, Australian National University, 0200 Canberra A.C.T., Australia
Viscous fingering is a prevalent phenomenon in dewetting polymer melts that arises at the interface between the moving liquid and the solid substrate. In our investigations we consider the fingering instability that occurs at the linear three phase contact line of a liquid polystyrene film. The film retracts from a highly non-wettable solid substrate only under the action of capillary driving forces. The investigations are realized by means of optical and atomic force microscopy under different external conditions. When dewetting starts, the material removed from the dewetted area forms a rim at the front of the receding film. The rim grows in size, and after a certain time, begins fluctuating in height and with. With increasing undulations, and further retracting of the contact line, material in the shape of fingers is left behind. The fingering is a consequence of an analogon of the Rayleigh-Plateau instability. The aim of our investigations is to show how parameters like molecular weight of the polymers, film thickness and slippage influence the dynamics and the morphology of the emerging finger structures. In particular, slippage and entanglement of the polymer seem to contribute to the understanding of the observed fingering instabilities.