Slip-controlled thin-film dynamics

R. Fetzer; M. Rauscher; A. Münch; B. A. Wagner; K. Jacobs

doi:doi:10.1209/epl/i2006-10160-3

Europhys. Lett., 75 (4), pp. 638-644 (2006)
DOI: 10.1209/epl/i2006-10160-3

Slip-controlled thin-film dynamics

R. Fetzer¹, M. Rauscher^{2, 3}, A. Münch^{4, 5}, B. A. Wagner⁵ and K. Jacobs¹

¹ Department of Experimental Physics, Saarland University 66123 Saarbrücken, Germany
² Max-Planck-Institut für Metallforschung - Heisenbergstr. 3 70569 Stuttgart, Germany
³ ITAP, University of Stuttgart - Pfaffenwaldring 57, 70569 Stuttgart, Germany
⁴ Institute of Mathematics, Humboldt University Berlin - 10099 Berlin, Germany
⁵ Weierstrass Institute for Applied Analysis and Stochastics Mohrenstr. 39, 10117 Berlin, Germany

received 13 March 2006; accepted in final form 4 July 2006
published online 19 July 2006

Abstract
In this study, we present a novel method to assess the slip length and the viscosity of thin films of highly viscous Newtonian liquids. We quantitatively analyse dewetting fronts of low-molecular-weight polystyrene melts on octadecyl- (OTS) and dodecyltrichlorosilane (DTS) polymer brushes. Using a thin-film (lubrication) model derived in the limit of large slip lengths, we can extract slip length and viscosity. We study polymer films with thicknesses between 50 $\un{nm}$ and 230 $\un{nm}$ and various temperatures above the glass transition. We find slip lengths from 100 $\un{nm}$ up to 1 $\un{\mu m}$ on OTS- and between 300 $\un{nm}$ and 10 $\un{\mu m}$ on DTS-covered silicon wafers. The slip length decreases with temperature. The obtained values for the viscosity are consistent with independent measurements.

PACS
83.80.Sg - Polymer melts.
47.15.gm - Thin film flows.
83.50.Lh - Slip boundary effects (interfacial and free surface flows).

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