Regensburg 2010 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 38: Micro and Nanofluidics II

CPP 38.3: Talk

Thursday, March 25, 2010, 10:00–10:15, H39

Equilibrium properties of polymer films and droplets — •Nikita Tretyakov and Marcus Müller — Institut für Theoretische Physik, Georg-August-Universität Göttingen

We study equilibrium properties of polymer films and droplets on a substrate by Molecular Dynamics simulation. We use a Lennard-Jones bead spring model for polymer chains and the substrate is represented by 2 layers of an fcc lattice. We use a dissipative particle dynamics (DPD) thermostat in our simulation. Various strengths of polymer-substrate interaction were used in order to tune the wettability.

The pressure tensor was calculated for different thicknesses of polymer films using a slab geometry. The values of the surface tensions of the substrate-liquid and liquid-vapor interfaces were derived. The wetting transition between complete (films) and partial wetting (droplets) was observed and the interface potential as function of thickness of the film was computed. The interface potential provides information about the contact angle and the stability of a thin film with respect to dewetting (spinodal or nucleation mechanisms). For ultra-thin films, no homogeneous layer can be observed and in this region the interface potential is a linear combination of contributions from the coexisting thin and thick films.