Dresden 2009 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 8: Glass I

DF 8.8: Vortrag

Dienstag, 24. März 2009, 12:20–12:40, WIL B321

Influence of surfaces on dynamics in polymer thin films - a molecular dynamics study — •Christian Vree and Stefan Georg Mayr — I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany

The influence of free surfaces on the mobility of model polymer chains is investigated with the help of classical molecular dynamics simulations. Below a critical temperature, T*, a strong enhancement of the mobility of chains near the surfaces is observed, as calculated from the center-of-mass displacements of the chains. This effect diminishes with increasing temperature. A similar behavior is observed in fluctuations of the radius of gyration, corresponding to conformation changes and hence to structural relaxations. Here the difference between surface and bulk decreases with increasing temperature as well as with increasing time. The temporal evolution of these fluctuations give rise to characteristic sampling times and, thus, activation energies of relaxations of the system. The activation energy for surface relaxations is found to be lower than for bulk relaxations and additionally less temperature dependent.

This work is financially supported by the DFG - SFB 602 (TP B3).

[1] C. Vree and S.G. Mayr, submitted to New Journal of Physics (2008)