Nonlinear Elasticity of Single Collapsed Polyelectrolytes

TL;DR

This paper investigates the nonlinear elastic behavior of short, stiff polyelectrolytes through dynamic simulations, revealing force-extension patterns and charge distributions that elucidate molecular elasticity and like-charge attraction mechanisms.

Contribution

It provides a physical interpretation of force-extension behaviors and characterizes counterion charge distributions in highly stretched polyelectrolytes, advancing understanding of molecular elasticity.

Findings

Identification of force plateau and stick-release patterns depending on electrostatic strength.

Explanation of force-extension behavior via intramolecular structure analysis.

Characterization of counterion charge distribution forming a correlated liquid at high Coulomb coupling.

Abstract

Nonlinear elastic responses of short and stiff polyelectrolytes are investigated by dynamic simulations on a single molecule level. When a polyelectrolyte condensate undergoes a mechanical unfolding, two types of force-extension curves, i.e., a force plateau and a stick-release pattern, are observed depending on the strength of the electrostatic interaction. We provide a physical interpretation of such force-extension behavior in terms of intramolecular structures of the condensates. We also describe a charge distribution of condensed counterions onto a highly stretched polyelectrolyte, which clarifies a formation of one-dimensional strongly correlated liquid at large Coulomb coupling regime where a stick-release pattern is observed. These findings may provide significant insights into the relationship between a molecular elasticity and a molecular mechanism of like-charge attractions observed in a wide range of charged biopolymer systems.