Programmable and Reversible 3D-to-3D Shape Transformation: Hierarchical Multimodal Morphing Based on Liquid Crystal Elastomers.

Achieving programmable morphing in 3D-to-3D shapes of soft actuators based on liquid crystal elastomer (LCE), particularly those with multimodal transformations and non-zero Gaussian curvature, remains a significant challenge. Here, a facile strategy is presented to create 3D LCE-elastomer (LCE-Ela) bilayer structures capable of customizable and programmable 3D-to-3D shape transformations, generating reversible and multimodal morphologies with nonzero Gaussian curvature. By combining two types of mismatch strains-pre-stretch and thermal strains-in LCE-Ela bilayer, the approach enables hierarchical multimodal transformations: starting from a 2D initial configuration, programmable transformations enable the formation of complex 3D structures, which can subsequently transition into other 3D shapes following predefined programs, with each step of the hierarchical process allowing multimodal deformations to generate diverse structural morphologies. Experimental and computational demonstrations include over 30 diverse 3D LCE-Ela configurations, the majority of which exhibit nonzero Gaussian curvature. Moreover, biomimetic LCE-Ela structures-including a chameleon, butterfly, spider, and leaf-demonstrate vivid deformation and discoloration, showcasing their potential for applications such as information encryption, camouflage, and adaptive devices. This work provides a facile approach to generate customizable 3D-to-3D transformations with complex geometries, broadening the application scope of LCE-based technologies in 3D soft actuators.