The deformable diversity of organisms in nature has inspired the development of bionic hydrogel actuators. However, the anisotropic structures of hydrogel actuators cannot be altered after the fabrication process, which restricts hydrogel actuators to provide complex and diverse shape deformations. Herein, we propose a dual programming method to generate numerous anisotropic structures from initial isotropic gelatin-containing hydrogels; the isotropic hydrogel blocks could be first assembled into anisotropic structures based on the coil-triple helix transition of gelatin, and then, the assembled hydrogels could further be fixed into various temporary anisotropies, so that they can produce complex and diverse deformations under the stimulation of pH. In addition, the shape programming and deformation behaviors are reversible. This dual programming method provides more potential for the application of hydrogel actuators in soft robots and bionics.

Living organisms can generate diverse three-dimensional (3D) morphologies and programmatically regulate their morphological evolution via the neurally controlled expansion and contraction of soft tissues. Although polymeric hydrogels have been regarded as an ideal experimental platform for biomimetic morphing due to their soft-tissue-like properties, it is still a tricky problem to quantitatively design their 3D morphological evolution, especially for inert polymeric hydrogels. In this study, we developed a muscle-inspired deformation system that could programmatically regulate the morphological evolution of undeformable inert polymeric hydrogels using large-deformable hydrogels as muscles, which contained smart poly N-isopropylacrylamide (PNIPAm) microgel and could be anchored onto any hydrogels via interfacial diffusion polymerization (IDP). Moreover, by programmatically regulating the anchoring position of the large-deformable muscle, the 3D morphology of kirigami-shaped hydrogels could further evolve to obtain a more complex 3D morphology. Surprisingly, when the inert hydrogel was replaced by a shape-memory hydrogel, the 3D morphologies could be fixed and preserved for more than 1 month without any stress relaxation or swelling, even after removing the hydrogel muscle or external stimuli. Therefore, we believe that this deformation strategy will enhance our understanding of the life evolution of natural soft-wet organisms for developing intelligent soft materials such as shape-memory hydrogels, programmable deformations, and 3D biomimetic devices.