Shape Changes of Liquid Crystal Elastomers Swollen by Low Molecular Weight Liquid Crystal Drops

TL;DR

This paper investigates how depositing low molecular weight liquid crystal droplets on liquid crystal elastomer films induces diverse shape changes and bending, driven by diffusion along the director, with potential applications in soft robotics and biomedical devices.

Contribution

It demonstrates that liquid crystal droplet swelling causes controllable shape transformations in LCEs, revealing the role of director alignment and diffusion in actuation.

Findings

Radially symmetric director alignments produce hat-shaped deformations.

Uniform director structures lead to arch-shaped bending.

Swelling can elevate the LCE top by up to 30 times, enabling powerful actuation.

Abstract

An elastomer swelling actuator deforms by absorbing a fluid, thus generating mechanical movement. We show that depositing small droplets of low molecular weight liquid crystal on liquid crystal elastomer (LCE) films leads to shape changes and bending actuation. It is found that the radially symmetric LCE director alignments provide radially symmetric hat shapes, while swelling LCEs with uniform director structure leads to arch shapes. Hybrid samples (different director alignments on two sides) lead to more complicated bent shapes. All the observed shapes can be explained by the diffusion that mainly progresses along the direction normal to the director of the LCE. The swelling induced bending force is elevating the top of the swollen LCE up to a factor of 30, providing a powerful and long-lasting actuation. These observations may lead to applications in various fields, like sealants, soft robotics and biomedical devices.