4D printing of carbon-fiber-reinforced liquid crystal elastomers for self-deployable solar panels

Deployable structures that can be switched from a folded state to a predetermined or desired configuration are of paramount significance for diverse technological applications, which require the development of advanced smart actuation materials with high mechanical strength and programmable shape-morphing ability. Herein, we present a short-carbon-fiber-reinforced liquid crystal elastomer (SCF-LCE) fabricated via 4D printing, which not only demonstrates enhanced tensile strength (13.5 MPa) and high actuation strain (27%) but also exhibits adaptive photoresponsive actuation. During the printing process, mesogens and SCF are oriented along the nozzle's moving direction by the extrusion shear force, enabling the formation of monodomain matrix materials. Importantly, the incorporation of passive layers onto the SCF-LCE enables programmable deformations and self-deployable structures. As a proof-of-the-concept, the SCF-LCE bilayer actuator is integrated with solar panels for a demonstration of self-adaptive solar panel unfolding system. The combination of enhanced mechanical properties and large driving strain in this short-fiber reinforced LCE is an accessible and influential approach to designing and fabricating LCE composites that may find potential applications in space deployable structures, soft robotics, artificial muscles, and beyond.