Programmable multimodal actuation in cholesteric liquid crystal elastomer hollow fibers beyond mechanochromism.

Abstract

Cholesteric liquid crystal elastomers (CLCEs) change color under strain, offering attractive prospects for soft robotics and photonic devices. However, the helical structure of CLCEs averages out the exceptional anisotropy and soft elasticity of the nematic phase, leaving little scope for also using the director orientation to program their thermal or mechanical actuation. Here, we develop programmable CLCE hollow fibers with longitudinal, circumferential, or twisted alignments via the integration of dynamic boronic ester bonds and mechanical force/pressure-induced orientation, all while preserving sufficient periodicity for structural color. Upon inflation, these fibers exhibit diverse motions-expansion, contraction, elongation, twisting-with synchronous color adaptation. Accordingly, we derive a membrane balloon model based on the non-ideal neo-classical LCE energy with suitable CLCE director profiles, successfully capturing key mechanical features including non-monotonicity and sub-criticality. This study provides a paradigm for the development of intelligent shape- and color-changing systems in a bespoke and versatile way.