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CPP: Chemische Physik und Polymerphysik

CPP 23: Polymer films I

CPP 23.3: Vortrag

Dienstag, 8. März 2005, 14:30–14:45, TU C130

Investigation of the dynamics of a Nanoparticle in a Polymer Film — •Juan G. Diaz-Ochoa, Wolfgang Paul, Kurt Binder, and Martin Aichele — Institut fuer Physik, Johannes Gutenberg Universitaet , Staudinger Weg 7, D-55099 Mainz

The dynamics of a nanoparticle on a polymer film is investigated via Molecular Dynamics (MD) techniques. The interaction between particle and the monomers of the melt is modeled with a modified Lennard-Jones potential; we consider that the particle has a perfect smooth surface and spherical shape, ignoring its atomistic structure. The system is micro canonical and the simulations are performed for melt temperatures between the glass transition Tc and the film dewetting temperature. We show that the motion of a particle three to four times bigger and twenty five times more massive than the monomers of polymer-chains (at this scale the gravitational force is too weak and will be not considered) is sensitive to the change of temperature of the melt.

For temperatures near Tc the mean square displacement shows for short times a transition from a ballistic into a sub diffusive regime; this effect is related to a ‘caging effect’ of the particle in the melt; for long times the subdiffusive regime evolves into a diffusive one. We show more over that the Dynamics of the particle depends of its size and is affected by the number of monomers in each polymer chain . For temperatures T>>Tc the behavior of the particle is similar to a conventional Brownian particle