Effective shape and phase behaviour of short charged rods

TL;DR

This paper calculates the effective shape and phase behavior of short charged rods in electrolytic solutions, revealing how charge and screening influence their liquid crystalline and crystalline phases.

Contribution

It introduces a method to determine effective rod dimensions and phase diagrams based on explicit second virial coefficient calculations considering electrostatic interactions.

Findings

Identification of regimes with nematic, smectic, and crystal phases

Effective dimensions depend on charge and screening length

Phase diagram mapped over a range of electrostatic parameters

Abstract

We explicitly calculate the orientation-dependent second virial coefficient of short charged rods in an electrolytic solvent, assuming the rod-rod interactions to be a pairwise sum of hard-core and segmental screened-Coulomb repulsions. From the parallel and isotropically averaged second virial coefficient, we calculate the effective length and diameter of the rods, for charges and screening lengths that vary over several orders of magnitude. Using these effective dimensions, we determine the phase diagram, where we distinguish a low-charge and strong-screening regime with a liquid crystalline nematic and smectic phase, and a high-charge and weak-screening regime with a plastic crystal phase in the phase diagram.