Europhys. Lett.
Volume 68, Number 3, November 2004
Page(s) 384 - 390
Section Atomic and molecular physics
Published online 16 October 2004
Europhys. Lett., 68 (3), pp. 384-390 (2004)
DOI: 10.1209/epl/i2003-10314-9

Dynamics of a polymer in a quenched random medium: A Monte Carlo investigation

A. Milchev1, 2, V. G. Rostiashvili1 and T. A. Vilgis1

1  Max Planck Institute for Polymer Research Ackermannweg 10, 55128 Mainz, Germany
2  Institute for Physical Chemistry, Bulgarian Academy of Sciences 1113 Sofia, Bulgaria

received 11 December 2003; accepted in final form 1 September 2004
published online 16 October 2004

We use an off-lattice bead-spring model of a self-avoiding polymer chain immersed in a 3-dimensional quenched random medium to study chain dynamics by means of a Monte Carlo (MC) simulation. The chain center-of-mass mean-squared displacement as a function of time reveals two crossovers which depend both on chain length N and on the degree of Gaussian disorder $\Delta$. The first one from normal to anomalous diffusion regime is found at short time $\tau_1$ and observed to vanish rapidly as $\tau_1\propto\Delta^{-11}$ with growing disorder. The second crossover back-to-normal diffusion, $\tau_2$, scales as $\tau_2\propto N^{2\nu+1}f(N^{2-3\nu}\Delta)$ with f being some scaling function. The diffusion coefficient DN depends strongly on disorder and drops dramatically at a critical dispersion $\Delta_{\ab{c}}\propto N^{-2+3\nu}$ of the disorder potential so that for $\Delta>\Delta_{\ab{c}}$ the chain center of mass is practically frozen. These findings agree well with our recent theoretical predictions.

36.20.-r - Macromolecules and polymer molecules.
71.55.Jv - Disordered structures; amorphous and glassy solids.
07.05.Tp - Computer modeling and simulation.

© EDP Sciences 2004