Non-Radical Photocured 3D Printing of Liquid Crystal Elastomers

Digital light processing (DLP) of liquid crystal elastomers (LCEs) enables the fabrication of complex architectures for soft robotics and energy-dissipative devices. However, conventional photocuring of LCE relies exclusively on radical-mediated polymerization, which involves acrylates homopolymerization inevitably, resulting in heterogeneous networks with uneven crosslinks, high crosslinking density and unreacted groups, leading to low rate of acceptable products due to cracking and constrained mesogen reorientation. It exhibits significantly higher defect rate for the products and printing cost, while compromising the material performance like damping and actuation behaviors. Here, we report a non-radical 3D printing strategy of LCEs using photobase generator (PBG). It promotes precise selectively thiol-acrylate Michael-addition, forming a homogenous network of low crosslinking density without residue thiols. It prevents cracking and guarantees a high success rate in printing. Also, it achieves the softest among all photocured LCEs with the Young's modulus of 1.69 MPa. Moreover, it liberates LC mesogen for easier reorientation, achieving higher actuation strain of 97% (<70% for radical-based counterparts) and a soft elasticity plateau 3 times wider, and enhancing damping capacity through synergistic mesogen reorientation and 3D architectural design. This strategy provides a high success route to high-performance 3D printed LCEs for soft robotics and impact protection.