Theory of relaxation properties of two-dimensional polymer networks, 2. Local dynamic characteristics

Abstract

Using normal mode transformation obtained in Part 1 of this series^[1], the exact analytical expressions for the mean-square displacements of junctions and non-junction beads, the autocorrelation functions of the end-to-end chain vectors between neighboring junctions, and those of subchain vectors of a two-dimensional regular network consisting of "bead and spring" Rouse chains are obtained. Contributions of intra- and interchain relaxation processes to the local dynamic characteristics considered are compared. The time behavior of dynamic quantities obtained is estimated for different scales of motions. The possibility of describing long-time relaxation of a two-dimensional network by a simplified coarse-grained network model is demonstrated. It is shown that the local relaxation properties of a two-dimensional polymer network (as well as a three-dimensional network) on scales smaller than the average distance between cross-links are very close to those of a single Rouse chain. The large-scale collective relaxation of the polymer networks having a two-dimensional connectivity differs considerably from that of the three-dimensional networks.