Finite Size Polyelectrolyte Bundles at Thermodynamic Equilibrium

TL;DR

This study uses advanced simulation techniques to explore how charged rod-like polyelectrolytes form finite size bundles or phase separate depending on electrostatic interaction strength, revealing conditions for thermodynamic stability.

Contribution

It demonstrates the formation and stability of finite size polyelectrolyte bundles at equilibrium through detailed computer simulations, highlighting the role of electrostatic interactions.

Findings

Finite size bundles form at certain electrostatic strengths.

Increased electrostatic interaction leads to phase separation.

Simulations reveal thermodynamic stability of aggregates.

Abstract

We present the results of extensive computer simulations performed on solutions of monodisperse charged rod-like polyelectrolytes in the presence of trivalent counterions. To overcome energy barriers we used a combination of parallel tempering and hybrid Monte Carlo techniques. Our results show that for small values of the electrostatic interaction the solution mostly consists of dispersed single rods. The potential of mean force between the polyelectrolyte monomers yields an attractive interaction at short distances. For a range of larger values of the Bjerrum length, we find finite size polyelectrolyte bundles at thermodynamic equilibrium. Further increase of the Bjerrum length eventually leads to phase separation and precipitation. We discuss the origin of the observed thermodynamic stability of the finite size aggregates.