Light‐Responsive Springs from Electropatterned Liquid Crystal Polymer Networks

• Published in: Advanced optical materials 2023-06, Vol.11 (12), p.n/a
• Main Authors: Ryabchun, Alexander, Lancia, Federico, Katsonis, Nathalie
• Format: Article
• Language: English
• Subjects: Actuation; artificial molecular switches; Biomimetics; chirality; Cholesteric liquid crystals; Crystals; Electric fields; liquid crystal networks; Liquid crystal polymers; liquid crystals; Materials science; Molecular machines; Movement; Optics; Patterning; soft robotics
• ISSN: 2195-1071; 2195-1071
• DOI: 10.1002/adom.202300358

Future robotic systems will have to adapt their operation to dynamic environments and therefore their development will require the use of active soft components. Bioinspired approaches toward novel actuation materials for active components rely on integrating molecular machines in soft matter, and ensuring that their nanoscale movement is amplified to the macroscale, where mechanically relevant motion is generated. This approach is successfully used in the design of photoresponsive soft springs and other mechanically active materials. Here, this study reports on a new approach where the operation of photoswitches and chiral liquid crystals are combined with an original and mask‐free microscopic patterning method to generate helix‐based movement at the macroscale, including light‐driven winding and unwinding accompanied with inversion of handedness. The microscopic patterning is the result of the unique organization of cholesteric liquid crystals under weak electric field. At a higher level, the pitch and the handedness of the active springs are defined by the imprinted pattern and the angle at which the spring ribbons are cut in the material. These findings are likely to enable soft and responsive robotic systems, and they show how transmission of molecular operation into macroscale functional movement is enabled by materials design across multiple hierarchical levels. A method for the design and synthesis of light‐responsive polymer springs is proposed. The material used for the springs is a chiral nematic liquid crystal that is patterned by application of a weak electric field. The pattern and chiral character of the material define the macroscopic geometrical parameters of the springs as well as their light‐induced actuation modes. These versatile elements can contribute to modern soft robotics.