Dynamics of Strongly Deformed Polymers in Solution

TL;DR

This paper investigates the complex dynamics of strongly deformed polymers in solution, revealing significant differences from linear models through a spectrum analysis and nonlinear response to flow changes.

Contribution

It introduces a method to determine the complete relaxation spectrum of nonlinear polymer models, highlighting differences from linear models and analyzing nonlinear flow responses.

Findings

Relaxation spectrum differs from linear Rouse model

Finite extensibility causes inhomogeneous tension distribution

Nonlinear response exhibits multiple decay regimes

Abstract

Bead spring models for polymers in solution are nonlinear if either the finite extensibility of the polymer, excluded volume effects or hydrodynamic interactions between polymer segments are taken into account. For such models we use a powerful method for the determination of the complete relaxation spectrum of fluctuations at {\it steady state}. In general, the spectrum and modes differ significantly from those of the linear Rouse model. For a tethered polymer in uniform flow the differences are mainly caused by an inhomogeneous distribution of tension along the chain and are most pronounced due to the finite chain extensibility. Beyond the dynamics of steady state fluctuations we also investigate the nonlinear response of the polymer to a {\em large sudden change} in the flow. This response exhibits several distinct regimes with characteristic decay laws and shows features which are beyond the scope of single mode theories such as the dumbbell model.