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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 26: Polymer Dynamics

CPP 26.1: Vortrag

Mittwoch, 16. März 2011, 10:30–10:45, ZEU 160

Local mobilities and chain end effects in non-entangled polymer melts - a molecular dynamics simulation study — •Diddo Diddens^1,2 and Andreas Heuer^1,2 — ¹Institut für physikalische Chemie, Universität Münster, Corrensstraße 30, 48149 Münster, Germany — ²NRW Graduate School of Chemistry, Corrensstraße 36, 48149 Münster, Germany

The dynamics of a polymer chain in a dense, non-entangled melt can be well described by the Rouse model. Within this model, the chain is composed of a series of Brownian beads connected by harmonic springs, where each bead is characterized by a uniform friction coefficient imposed by the surrounding chains. However, when probing the bead’s mean square displacement, the chain ends move faster than the central monomers for topological reasons, and the chain ends have on average more intermolecular neighbors.

Using a newly developed method [1] we study the dependence of the local chain dynamics on the bead position by direct determination of the local friction coefficient. In this way, the Rouse assumption of uniform friction coefficients along the entire chain and specifically at the chain end is tested for an all-atom MD simulation of a poly(ethylene oxide) (PEO) melt. In particular, the interplay of the surroundings of a given monomer and the friction coefficient is discussed. Furthermore we analyze whether the forward-backwards dynamics of the monomers is compatible with the predictions of the Rouse model.

[1] D. Diddens, M. Brodeck, A. Heuer, EPL 91 (2010) 66005