Morphing of stiffness-heterogeneous liquid crystal elastomers via mechanical training and locally controlled photopolymerization

The large, reversible shape-changing behaviors of liquid crystal elastomers (LCEs), resulting from liquid crystal-polymer network couplings, are promising for many applications. Despite intensive studies, harnessing molecular-material-structure interactions of LCEs for the design of locally controlled shape-morphing structures remains a challenge. Here, we report a facile and versatile strategy to tailor the stiffness and the morphing behavior of reconfigurable LCE structures via locally controlled mesogen alignment and crosslinking densities. Selective photopolymerization of spatially aligned LCE structures yields well-controlled lightly and highly crosslinked domains of distinct stiffness and selective permanent mesogen programming, which enables various previously inaccessible stiffness-heterogeneous geometries, as demonstrated in diverse morphing LCE structures via integrated experimental and finite element analysis. Furthermore, programming of the non-photopolymerized regions allows for reshaping, as shown in a sequentially shape-morphing LCE rod and “face”. The heterogenous morphing LCE structures have the potential for many applications, including in artificial muscles, soft robotics, and many others.