Silk Fibroin‐Regulated Shape Memory Composite Hydrogels with Tunable Recovery Time

ABSTRACT Shape memory polymers (SMPs) are pivotal for applications in soft robotics, biomedical devices, and flexible electronics. However, their reliance on external stimuli for activation and the difficulty of precisely programming recovery dynamics remain significant limitations. Autonomous SMPs with delayed recovery offer a promising alternative, yet facile control of recovery onset and duration is still difficult to attain. Here, a semi‐interpenetrating network (semi‐IPN) hydrogel composed of poly(acrylic acid) and silk fibroin (PAA‐SF) is presented, fabricated via a facile one‐step UV polymerization. By modulating the SF content within the PAA network, the hydrogel exhibits tunable shape recovery kinetics across multiple programming environments, including organic solvents, air, and water, enabling spatiotemporal control over shape restoration. Moreover, the hydrogels show significantly enhanced mechanical properties and strong adhesion compared to neat PAA hydrogels. Benefiting from these combined properties and excellent cytocompatibility, demonstrating two proof‐of‐concept devices: a smart four‐jaw gripper capable of retrieving objects in confined spaces, and a stiffness‐switchable needle that reversibly transitions between soft and rigid states. This work not only introduces a robust and multifunctional shape memory hydrogel but also provides a versatile platform for designing stimulus‐free, time‐programmable soft actuators for biomedical and robotic applications.