Giant deformations and soft-inflation in LCE balloons

TL;DR

This paper explores how liquid crystal elastomer balloons can be controlled and amplified for actuation through their unique deformation properties, including phase-separation and soft modes, leading to enhanced ballooning behaviors.

Contribution

It introduces the use of LCEs for controlled ballooning, highlighting their large spontaneous deformations and soft-mode mechanics that enable novel inflation behaviors.

Findings

LCE balloons exhibit phase-separation and volume jumps during inflation.

Soft modes allow for rotation-driven ballooning between different states.

Enhanced actuation strains are achieved through LCE properties.

Abstract

We propose that ballooning can be controlled, enriched and amplified by using rubbery networks of aligned molecular rods known as liquid crystal elastomers (LCEs). Firstly, LCEs are promising artificial muscles, showing large spontaneous deformations in response to heat and light. In LCE balloons, spontaneous deformations can trigger classic ballooning, either as phase-separation (at constant volume) or a volume jump (at constant pressure), resulting in greatly magnified actuation strains. Secondly, even at constant temperature, LCEs have unusual mechanics augmented by soft-modes of deformation in which the nematic director rotates within the elastomer. These soft modes enrich the mechanics of LCE balloons, which can also "balloon" between rotated and unrotated states, either during the classic instability, or as a separate pre-cursor, leading to successive instabilities during inflation.