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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 35: Poster: Micro- and Nanofluidics

CPP 35.6: Poster

Mittwoch, 16. März 2011, 17:00–19:00, P2

Effects of concentration-dependent wettability on the statics and dynamics of droplets of mixtures and suspensions — •Desislava V Todorova and Uwe Thiele — School of Mathematics, Loughborough University, Leicestershire, LE11 3TU, United Kingdom

We discuss the behaviour of small drops of non-volatile liquid mixtures, colloidal suspensions and polymer solutions on a solid substrate. A hydrodynamic long-wave model is developed to analyze static and moving contact lines in the case of partially wetting liquids that show a concentration-dependent wettability. Thereby, Hamaker constants for mixtures are obtained employing homogenization techniques [1].

The model is used to study static drop profiles, in particular, the change of the equilibrium contact angle with mean solute concentration. Following this, we focus on sliding drops and look at the change of dynamic contact angles and drop profiles with concentration for the cases of constant and concentration-dependent viscosity. Individual drop and concentration profiles and characteristics of solution families are obtained employing numerical continuation and time simulation techniques [2].

[1] G. A. Niklasson, C. G. Granqvist, O. Hunderi, Appl. Optics 20, 26-30 (1981); D. Todorova et al., J. Optoelectron. Adv. Mater. 11, 1296-1299 (2009)

[2] E. Doedel, H.B. Keller, J.P. Kernevez, Int. J. Bifurcation Chaos 1, 493-520 (1991); P. Beltrame, U. Thiele, SIAM J. Appl. Dyn. Syst. 9, 484-518 (2010)

We acknowledge support by the EU (PITN-GA-2008-214919).