Improved actuation of liquid crystal elastomers via solvent engineering

Abstract

Liquid crystal elastomers (LCEs), soft elastic networks with liquid crystal molecules, exhibit notable energydissipating and shape memory properties. This study explored how removed solvent in post-polymerization influences the structural and actuation characteristic of LCEs. By systematically varying solvent content during synthesis and evaluating post-polymerization effects, we discovered that solvent levels critically modulate actuation strain and stress through mesogen mobility and cross-linking density. Higher solvent content increased actuation strain up to 38.6 %, maintaining actuation stress of 0.11 MPa, but diminished it at excessive levels due to reduced mesogen concentration. Structural analyses via polarized optical microscopy, positron annihilation lifetime spectroscopy, and WAXS underscored the formation of expanded mesogen domains and changes in mesogen rotation behavior. These insights offer a pathway for customizing the performance of LCEs, enabling more precise and adaptable soft actuators in next-generation technologies.