Printing Mosaics of Magnetically Programmed Liquid Crystal Directors for Reversibly Morphing Soft Matter

Liquid crystal elastomers (LCEs) can act as smart materials for 4D printing, where the material changes shape reversibly when stimulated. The abstract notes that magnetic-field alignment has been rarely used in 4D printing because it typically needs high field strength and has low printing efficiency. The authors report a digital light projection (DLP) setup integrated with a reorientable magnetic field to print LCE structures. They propose an LCE precursor solution that stays in a liquid-crystalline nematic phase and remains flowable at room temperature, allowing magnetic alignment before photopolymerization. They state that the resin can be aligned by a 500 mT magnetic field within seconds without temperature elevation or cycling. The printed structures show reversible thermal actuation greater than 30%, and the method supports local, arbitrary magnetic-field alignment across layers during printing. Finally, the abstract describes selective deformation using a photo-thermal effect to program molecular orientation, and suggests potential uses in soft robotics, biomedical structures, and microelectronics.