Movement with light: Photoresponsive shape morphing of printed liquid crystal elastomers

Soft machines will require soft materials that exhibit a rich diversity of functionality, including shape morphing and photoresponsivity. The combination of these functionalities enables useful behaviors in soft machines that can be further developed by synthesizing materials that exhibit localized responsivity. Localized responsivity of liquid crystal elastomers (LCEs), which are soft materials that exhibit shape morphing, can be enabled by formulating composite inks for direct ink writing (DIW). Gold nanorods (AuNRs) can be added to LCEs to enable photothermal shape change upon absorption of light through a localized surface plasmon resonance. We compared LCE formulations, focusing on their amenability for printing by DIW and the photoresponsivity of AuNRs. The local responsivity of different three-dimensional architectures enabled soft machines that could oscillate, crawl, roll, transport mass, and display other unique modes of actuation and motion in response to light, making these promising functional materials for advanced applications. [Display omitted] •Optimized inks for additive manufacturing of a liquid crystal elastomer composite•Developed spatiotemporal control during printing for complex three-dimensional structures•Demonstrated unique combinations of complex three-dimensional photoresponsive actuation•Controlled novel modes of actuation with computer vision techniques Soft matter that can adapt in response to a stimulus like light holds immense promise for various applications, such as biomedical devices and soft robotics. One example of adaptive soft matter is liquid crystal elastomer composites, which incorporate a functional additive and change shape through a phase transition. The combination of the material composition, the printed geometry of the material, and the localization of the stimulus can enable novel movement and reaction to light, as we demonstrate in this paper. Our results mark a significant advancement toward creating complex, 3D-printed, intelligent materials that pave the way for developing next-generation adaptive machines and devices that can transform in response to specific stimuli. In this paper, Ford et al. describe multifunctional material development for additive manufacturing. By controlling formulation properties and optimizing inks, they demonstrate precise 3D printing of gold nanorod/liquid crystal elastomer composites with spatiotemporal control. These structures exhibit unique photoresponsive actuation, sho