Stereo-selective swelling of imprinted cholesteric networks

TL;DR

This study demonstrates a novel method for stereo-selective separation of chiral isomers using a cholesteric elastomer with topologically imprinted helical director distribution, enabling selective swelling based on handedness.

Contribution

The paper introduces a new experimental approach utilizing cholesteric elastomers with topological imprinting for stereo-specific chiral separation, highlighting the role of network parameters in demixing.

Findings

Selective swelling occurs only for the correct handedness of chiral isomers.

The twist-untwist transition is controlled by network parameters.

Demixing efficiency depends on the nematic order and network characteristics.

Abstract

Molecular chirality, and the chiral symmetry breaking of resulting macroscopic phases, can be topologically imprinted and manipulated by crosslinking and swelling of polymer networks. We present a new experimental approach to stereo-specific separation of chiral isomers by using a cholesteric elastomer in which a helical director distribution has been topological imprinted by crosslinking. This makes the material unusual in that is has a strong phase chirality, but no molecular chirality at all; we study the nature and parameters controlling the twist-untwist transition. Adding a racemic mixture to the imprinted network results in selective swelling by only the component of ``correct'' handedness. We investigate the capacity of demixing in a racemic environment, which depends on network parameters and the underlying nematic order.