SINGLE-CHAIN DIFFUSION-COEFFICIENT IN TRANSIENT NETWORKS AND STRONG SOLUTIONS

The static and hydrodynamic screening lengths in transient polymer net works and strong solutions are investigated. Arguments of the blob mod el are used to examine the static properties of these systems and in p articular the correlation length for the excluded volume interaction. The dynamic properties are deduced from the model developed originally by Edwards and coworkers and extended by Shiwa et nl. The dynamic cor relation length for hydrodynamic screening is deduced from this model and used for the calculation of the single chain diffusion coefficient , D-s, in transient polymer networks and strong solutions. When no dis tinction is made between static and dynamic correlation lengths, one g ets a power law behavior of D-s as similar to c(-1/2) at the theta tem perature and c(-1) in the presence of excluded volume interaction. Whe n the dynamic model of Edwards, Shiwa, and coworkers is used, a hydrod ynamic screening length different from the static length is derived an d its scaling with the polymer concentration is obtained in the theta temperature conditions. This model leads to a different scaling law of the self diffusion coefficient D-s similar to C-2 which is closer to the experimental observations that suggest a scaling law between c(-1. 75) and C-3.