Top-Down approach for fabricating high-driving-stress wood-based hydrogel for load-bearing

In this study, a top-down approach was adopted to design and develop a wood-based hydrogel with high driving stress, which is used to achieve heavy object lifting and efficient load-bearing. Using the wood cellulose network as the framework and 3-Sulfopropyl acrylate potassium salt (SPA)as the filler, and leveraging the anisotropic expansion behavior of wood cellulose (tangential > radial),   we constructed a confined space via a semipermeable membrane to fabricate the wood-based hydrogel. The assembled wood-based hydrogel can exhibit extraordinary mechanical deformation ability and efficient mechanical output when stimulated by external moisture. The driving force of the wood-based hydrogel can reach 951 N, and the driving stress can reach 1.1 MPa, which is much higher than the polymer hydrogels in current research. In addition, the wood-based hydrogel has excellent swelling properties in different pH environments. Among them, in a NaCl solution with a pH of 7, its compressive strength can reach 1.24 MPa. The wood-based hydrogel we prepared not only has excellent cyclic stability and high driving stress, but also can lift a 100 g heavy object by 12 mm in just 6 min under low-voltage osmotic driving conditions. In the future, our wood-based hydrogel is expected to play an important role in fields such as soft robots, automated handling, and bionic load-bearing materials.