Regensburg 2013 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 22: Focus: Wetting on smooth and rough surfaces: From spreading to superhydrophobicity I

CPP 22.6: Talk

Wednesday, March 13, 2013, 11:00–11:15, H34

Dewetting of mixtures as described by a gradient dynamics model — •Uwe Thiele, Desislava Todorova, and Hender Lopez — Department of Mathematical Sciences, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK

We show that the dynamics of free surface films of mixtures (polymer blends, nanoparticle suspensions) may be described by a hydrodynamic long-wave model that is written thermodynamically inspired gradient dynamics form based on an underlying free energy functional (accounting for wettability and capillarity). For an ideal mixture whose components do not differ in their wettability, the *classical* hydrodynamic model used, e.g., in Refs. [1,2] is recovered. The gradient dynamics form allows us to extend the model to incorporate (i) solute-dependent wettability, and (ii) solute-solvent decomposition [3]. We illustrate extension (i) by an investigation of the dewetting of a film of a mixture and show that a film may become unstable through the coupling of film height and concentration fluctuations. The resulting nonlinear dynamic behaviour and equilibrium states are discussed [4]. The outlook discusses how the idea also applies to surfactant-covered films [5]. We acknowledge support by the EU (PITN-GA-2008-214919).

[1] M. Warner, R. Craster and O. Matar. J. Colloid Interface Sci. 267, 92 (2003). [2] L. Frastia, A.J. Archer, U. Thiele, Phys. Rev. Lett. 106, 077801 (2011); Soft Matter 8, 11363 (2012). [3] U. Thiele, Eur. Phys. J. Special Topics, 197, 213-220 (2011). [4] D. Todorova, H. Lopez and U. Thiele, in prep. [5] U. Thiele, A.J. Archer and M. Plapp, Phys. Fluids 24, 102107 (2012).