Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 13: Polymer Physics IV: Thin Films

CPP 13.4: Talk

Tuesday, March 27, 2007, 15:15–15:30, H40

Demixing and dewetting in films of binary mixtures — •Santiago Madruga and Uwe Thiele — Max Planck Institute for the Physics of Complex Systems, Noethnitzer Str. 38, 01187 Dresden

Thin polymer films are often used in advanced technological applications either as homogeneous coatings or as structured functional layers. Their stability and therefore potential usage is mostly determined by the wettability properties of the substrate and is rather well understood for single component liquids.

However, in various applications the film consists of a binary mixture such as a polymer blend. Then the dynamics of the decomposition in the film and of dewetting of the film couple. This allows for new pathways of structuring like decomposition induced dewetting [1]. We complete the bulk description of the dynamics of a binary mixture (model-H) [2] with boundary conditions for the evolving free surface.

The model is used to analyse the spinodal decomposition of a film of a binary mixture. The composition gradients give rise to a solutal Marangoni effect that modifies the dynamics deeply. Linear results obtained with the full transport equations for (a) purely diffusive transport described by the Cahn-Hilliard equation and (b) diffusive and convective transport described by model-H between parallel plates are compared to the case of a free surface.

We acknowledge support by the EU under grant MRTN-CT-2004-005728. [1] R. Yeushalmi-Rozen, T. Kerle, and J. Klein. Science. 285, 1254-1256 (1999); [2] D.M. Anderson, G.B. McFadden, and A.A.Wheeler. Ann. Rev. Fluid Mech. 30, 139-165 (1998).