Site‐Specific Pre‐Swelling‐Directed Morphing Structures of Patterned Hydrogels

Morphing materials have promising applications in various fields, yet how to program the self‐shaping process for specific configurations remains a challenge. Herein we show a versatile approach to control the buckling of individual domains and thus the outcome configurations of planar‐patterned hydrogels. By photolithography, high‐swelling disc gels were positioned in a non‐swelling gel sheet; the swelling mismatch resulted in out‐of‐plain buckling of the disc gels. To locally control the buckling direction, masks with holes were used to guide site‐specific swelling of the high‐swelling gel under the holes, which built a transient through‐thickness gradient and thus directed the buckling during the subsequent unmasked swelling process. Therefore, various configurations of an identical patterned hydrogel can be programmed by the pre‐swelling step with different masks to encode the buckling directions of separate domains.