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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 37: Molecular Dynamics

CPP 37.4: Vortrag

Freitag, 29. Februar 2008, 11:15–11:30, C 230

Surface diffusion of single polymer chains - a molecular dynamics study — •Christian Vree and S. G. Mayr — I. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen

Bulk diffusion and transport of polymers in melts and solutions have attracted large scientific interest during the past decades in particular with respect to the influence of solvants, chain length, conformation and temperature. Contrary, surface kinetics of polymers are still poorly understood, although there is increasing interest in this field. Surface diffusion is of great importance in thin film physics, i.e. in physical vapor deposition methods. Therefore it is essential to understand the microscopic mechanisms of surface diffusion in more detail.

Here we present molecular dynamics studies of a polymer chain on a surface of a thin film of the same type of polymer. A cubic box with periodic boundary conditions in x- and y-direction and free surfaces in z-direction with typical dimensions of 42σ× 42σ× 30σ, where σ is the bond length in Lennard-Jones units, acts as the substrate, where a single chain is placed on. Non-bonded particles interact via a truncated Lennard-Jones potential, while bonded particles interact via the FENE-potential suggested by Kremer and Grest (J. Chem. Phys. 92, 5057, 1990). We find that the mobility on the surface is increased compared to the bulk value by about a factor of 2, while the time scaling does not change significantly.

This work is financially supported by the DFG SFB 602 (TP B3), as well as the GIF No. 1428-303.1/2004.