Regensburg 2007 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 12: Polymer Physics III: Interfaces
CPP 12.1: Talk
Tuesday, March 27, 2007, 10:00–10:15, H40
Monte Carlo simulations of tethered chains in contact with an adsorbing surface — •Radu Descas1, Jens-Uwe Sommer2, and Alexander Blumen1 — 1Albert-Ludwigs-University, Theoretical Polymer Physics, Freiburg — 2Technical University of Dresden, Institute for Theoretical Physics, Dresden
We use MC simulations combined with scaling arguments to study the adsorption of tethered polymer chains at flat surfaces [1]. In the two-dimensional semi-dilute surface regime we analyze the average extension of single chains in the direction parallel and perpendicular to the surface. Our simulation results agree well with previous scaling predictions [2], especially for the parallel extension of the chains and much below the saturation concentration of the adsorbed layer. Increasing the surface concentration, saturation effects influence the adsorption free energy. The investigation of the free energy function leads us to propose a new scaling parameter which controls the saturation behavior in polymer layers. The strong decrease of the fraction of adsorbed monomers per chain with increasing concentration confirms our assumptions. Based on our model we infer the existence of a crossover-scaling region between the semi-dilute and the saturated state. Our results for the chains’ extension give further support to our scaling model. Furthermore, we investigate the over-saturated surface regime which can be understood as the coexistence of a brush-like layer formed on top of a saturated adsorption layer.
[1] R. Descas, J.-U Sommer, and A. Blumen, J. Chem. Phys. in press.
[2] E. Bouchaud and M. Daoud, J. Physique 48, 1991 (1987).