Programming Shape Memory Hydrogel to a Pre‐Encoded Static Deformation toward Hierarchical Morphological Information Encryption

Abstract Morphological information encryption such as gesture and sign language is a traditional but efficient way of information storage and communication. However, due to the limited deformability, almost all of the existing information encryption materials store and deliver information via the pattern or color changes on the 2D plane. Herein, a thermo and ion dual‐responsive shape memory hydrogel containing short alkyl chains modified polyvinyl alcohol (PVA‐C6) and polyacrylamide‐co‐polyacrylic acid [P(AAm‐co‐AAc)], is prepared. In this system, the ion‐responsive shape memory process of P(AAm‐co‐AAc) provides the preprogrammed morphological information and actuating force while the thermo‐responsive hydrophobic clusters of PVA‐C6 are utilized as a molecular switch to control the deformed posture within the deformation process. Incorporated with a photothermal particle, Fe 3 O 4 , the photothermal PVA‐C6 hydrogel is capable of generating diverse configurations that can be encoded as the corresponding information. With the assistance of the programmable NIR, the hydrogel can transfer to the encoded configuration and decrypt the information. Besides, the obtained morphological information can also be erased by immersing the hydrogel in hot water, in order to avoid the leakage of information. This study motivates the design and fabrication of deformable materials and provides a new insight into the information encrypt materials.