Single chain dynamics in polymer networks: A Monte Carlo study

We investigated the dynamics of single chains diffusing in cross-linked polymer networks using the three-dimensional bond fluctuation method. We considered single chain dynamics in dry polymer networks, at monomer density of 0.51, and similarly, in networks swollen up to the maximum degree of swelling. In order to compare time scales at different degrees of network swelling we calculated the single monomer relaxation time tau(0), which showed a strong decrease with swelling. The scaling laws of terminal relaxation times tau(d) and the diffusion coefficients D as function of renormalized chain length covered both the Rouse and the entangled regime. We found that the entanglement length N-e as function of monomer density of the network has similar values to those calculated for polymer melts, at the same concentration. The effect of fixed topological constraints in polymer networks on the concentration dependence of the entanglement length is discussed.