Enhancement of coil-stretch hysteresis by self-concentration in polymer solutions

TL;DR

This paper investigates how concentration affects coil-stretch hysteresis in polymer solutions, revealing that intermolecular interactions significantly enhance hysteresis width near the critical overlap concentration.

Contribution

It introduces a combined approach of Brownian dynamics simulations and scaling theory to analyze non-dilute polymer solutions, highlighting the role of self-concentration effects.

Findings

Hysteresis window width is strongly increased near the critical overlap concentration.

Intermolecular overlap and hydrodynamic screening occur at concentrations below $c^*$.

Stretched polymers occupy larger volumes than equilibrium coils in the hysteresis regime.

Abstract

The effect of concentration on coil-stretch hysteresis in extensional flows of polymer solutions is examined with insights from Brownian dynamics simulations of isolated chains and scaling theory for non-dilute solutions. In the hysteresis regime, stretched molecules pervade larger volumes than equilibrium coils. For such chains, intermolecular overlap and hydrodynamic screening crossover set in at concentrations much smaller than the critical overlap concentration $c^\ast$ for equilibrium coils. The width of the hysteresis window is consequently strongly enhanced around $c^\ast$.