Polyelectrolyte Condensation Induced by Linear Cations

TL;DR

This study uses simulations to explore how linear divalent cations induce polyelectrolyte condensation, revealing length-dependent behaviors and nonmonotonic effects on bundle stability consistent with experimental observations.

Contribution

It provides new insights into the effects of cation length and surface charge density on polyelectrolyte bundling, explaining experimental phenomena through simulation.

Findings

Short cations induce condensation consistent with experiments.

Longer cations cause novel alignment-driven condensation.

Bundle stability varies nonmonotonically with charge density.

Abstract

We examine the role of the condensing agent in the formation of polyelectrolyte bundles, via grand-canonical Monte Carlo simulations. Following recent experiments we use linear, rigid divalent cations of various lengths to induce condensation. Our results clarify and explain the experimental results for short cations. For longer cations we observe novel condensation behavior owing to alignment of the cations. We also study the role of the polyelectrolyte surface charge density, and find a nonmonotonic variation in bundle stability. This nonmonotonicity captures two trends that have been observed in separate experiments.