Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 15: POSTERS Dynamics and Diffusion

CPP 15.1: Poster

Dienstag, 24. März 2009, 14:00–16:30, P3

Monte Carlo simulations of chain dynamics in crosslinked polymer networks — Sorin Nedelcu and •Jens-Uwe Sommer — Leibniz Institute of Polymer Research Dresden, Germany

We consider the reptation dynamics of freely diffusive long chains in monomodal, crosslinked polymer networks in a dry state, and then in a swollen state. The chain terminal relaxation time shows an increase with the network degree of swelling (Q), with an exponent of about 0.37+/-0.1, while the center of mass diffusion coefficient remains almost constant with Q. The monomer friction coefficient decreases with Q vary rapidly, with a coefficient of approximately -1.3, and this Q-dependence explains why the diffusion coefficient does not change. We also present a dynamical scaling theory to compare with our simulation results, and comparisons with de Gennes predictions for semi-dilute solutions. An important finding is that the number of entanglements that a chain can form seems to vary very little with the network degree of swelling, which is explained by a nonaffine deformation of the network by swelling. The case of unentangled, short chains diffusing in the polymer network, and a comparison with long chain dynamics is briefly reviewed.