The Rouse-Zimm-Brinkman theory of the dynamics of polymers in dilute solutions

TL;DR

This paper develops a unified theory for polymer dynamics in dilute solutions, incorporating hydrodynamic screening effects and bridging the Rouse and Zimm models, with implications for solution viscosity and relaxation behaviors.

Contribution

It introduces a comprehensive model that accounts for hydrodynamic screening and transitions between Rouse and Zimm behaviors based on polymer concentration.

Findings

Hydrodynamic screening affects polymer diffusion and relaxation.

Transition from Zimm to Rouse behavior with increasing coil concentration.

Calculated viscosity and Huggins coefficient differ from classical results.

Abstract

We propose a theory of the dynamics of polymers in dilute solution, in which the popular Zimm and Rouse models are limiting cases of infinitely large and small draining parameter. The equation of motion for the polymer segments beads) is solved together with Brinkman's equation for the solvent velocity that takes into account the presence of other polymer coils in the solution. The equation for the polymer normal modes is obtained and the relevant time correlation functions are found. A tendency to the time-dependent hydrodynamic screening is demonstrated on the diffusion of the polymers as well as on the relaxation of their internal modes. With the growing concentration of the coils in solution they both show a transition to the (exactly) Rouse behavior. The shear viscosity of the solution, the Huggins coefficient and other quantities are calculated and shown to be notably different from the known results.