Phase chirality and stereo-selective swelling of cholesteric elastomers

TL;DR

This paper investigates how cholesteric elastomers exhibit phase chirality and stereo-selective swelling, revealing their ability to retain specific solvent chirality and how their optical properties vary with temperature and solvent uptake.

Contribution

It introduces the measurement of optical rotation to analyze the variation of phase chirality and local nematic order in cholesteric elastomers, demonstrating stereo-selectivity in solvent absorption.

Findings

Cholesteric elastomers show pronounced stereo-selectivity.

Optical rotation measurements reveal changes in phase chirality.

The study quantifies stereo-separation dynamics.

Abstract

Cholesteric elastomers possess a macroscopic ``phase chirality'' as the director n rotates in a helical fashion along an optical axis $z$ and can be described by a chiral order parameter. This parameter can be tuned by changing the helix pitch p and/or the elastic properties of the network. The cholesterics also possess a local nematic order, changing with temperature or during solvent swelling. In this paper, by measuring the power of optical rotation, we discover how these two parameters vary as functions of temperature or solvent adsorbed by the network. The main result is a finding of pronounced stereo-selectivity of cholesteric elastomers, demonstrating itself in the retention of the ``correct'' chirality component of a racemic solvent. It has been possible to quantify the amount of such stereo-separation, as the basic dynamics of the effect.