Discontinuous Metric Programming in Liquid Crystalline Elastomers

Liquid crystalline elastomers (LCEs) are shape-changing materials that exhibit large deformations in response to applied stimuli. Local control of the orientation of LCEs spatially directs the deformation of these materials to realize a spontaneous shape change in response to stimuli. Prior approaches to shape programming in LCEs utilize patterning techniques that involve the detailed inscription of spatially varying nematic fields to produce sheets. These patterned sheets deform into elaborate geometries with complex Gaussian curvatures. Here, we present an alternative approach to realize shape-morphing in LCEs where spatial patterning of the crosslink density locally regulates the material deformation magnitude on either side of a prescribed interface curve. We also present a simple mathematical model describing the behavior of these materials. Further experiments coupled with the mathematical model demonstrate the control of the sign of Gaussian curvature, which is used in combination with heat transfer effects to design LCEs that self-clean as a result of temperature-dependent actuation properties.

Automated summary

Liquid crystalline elastomers (LCEs) are shape-changing materials that undergo large deformations in response to stimuli. By locally controlling the orientation of LCEs, we can achieve spontaneous shape changes in these materials. In this study, we propose a novel approach to shape-morphing in LCEs by spatially patterning the crosslink density to regulate the material deformation on a prescribed interface curve. We also develop a simple mathematical model to describe the behavior of LCEs. Through experiments and mathematical modeling, we demonstrate the control of Gaussian curvature and design self-cleaning LCEs based on temperature-dependent actuation properties.