Nonlinear elasticity of single collapsed polyelectrolytes

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 charge distributions of counterions condensed onto a polyelectrolyte, which clarify formation of one-dimensional strongly correlated liquid at large Coulomb coupling regime. 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.