Molecularly‐Engineered, 4D‐Printed Liquid Crystal Elastomer Actuators

• Published in: Advanced functional materials Vol. 29; no. 3
• Main Authors: Saed, Mohand O., Ambulo, Cedric P., Kim, Hyun, De, Rohit, Raval, Vyom, Searles, Kyle, Siddiqui, Danyal A., Cue, John Michael O., Stefan, Mihaela C., Shankar, M. Ravi, Ware, Taylor H.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 17.01.2019
• Subjects: 4D printing; Actuation; actuators; Chemical synthesis; Crystal structure; Crystals; Elastomers; Inks; liquid crystal elastomers; Liquid crystals; Materials science; Medical devices; Medical electronics; Medical equipment; Morphing; multi‐materials printing; Phase transitions; soft robots; Three dimensional printing; Transition temperature
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201806412

Three‐dimensional structures that undergo reversible shape changes in response to mild stimuli enable a wide range of smart devices, such as soft robots or implantable medical devices. Herein, a dual thiol‐ene reaction scheme is used to synthesize a class of liquid crystal (LC) elastomers that can be 3D printed into complex shapes and subsequently undergo controlled shape change. Through controlling the phase transition temperature of polymerizable LC inks, morphing 3D structures with tunable actuation temperature (28 ± 2 to 105 ± 1 °C) are fabricated. Finally, multiple LC inks are 3D printed into single structures to allow for the production of untethered, thermo‐responsive structures that sequentially and reversibly undergo multiple shape changes. Novel inks for printable liquid crystal elastomers (LCEs) are reported herein. The 3D‐printed LCE structures undergo controlled and reversible shape change upon heating. By controlling the reaction parameters (e.g., reaction type, mesogen concentration, or crosslinking density), a wide range of LCEs are synthesized and characterized for their use as soft actuators.