Three-Dimensional Printing of Liquid Crystal Elastomers and Their Applications

Liquid crystal elastomers (LCEs), which are composed of liquid crystal mesogens and polymer networks, exhibit excellent actuation performance and tailorable energy dissipation behavior. They have shown great potential in practical applications in artificial muscles, soft robotics, and wearable devices. However, it is challenging to fabricate LCE samples in arbitrary three-dimensional (3D) shapes and desired alignment patterns with traditional manufacturing methods. Recently, 3D printing techniques have been introduced in combination with alignment methods of LCEs to meet this challenge. In this Review, we highlight recent advances in the 3D printing techniques of LCEs. Two kinds of printing techniques, materials extrusion and vat photopolymerization, are discussed in detail. We compare the differences and key parameters in the printing techniques, such as director fields, resolutions, and printing speeds. The applications of the printed LCE structures in soft robots, reconfigurable surfaces, and haptic devices are also introduced.