3D‐Printed Hydrogels with High‐Strength and Anisotropy Mediated by Chain Rigidity

Abstract Extrusion‐based 3D printing is a facile technology to construct complex structures of hydrogels, especially for tough hydrogels that have shown demonstrated potential in load‐bearing materials and tissue engineering. However, 3D‐printed hydrogels often possess mechanical properties that do not guarantee their usage in tissue‐mimicking, load‐bearing components, and motion sensors. This study proposes a novel strategy to construct high‐strength and anisotropic Fe3+ cross‐linked poly(acrylamide‐co‐acrylic acid)/sodium alginate double network hydrogels. The semi‐flexible sodium alginate chains act as a “conformation regulator” to promote the formation of strong intermolecular interactions between polymer chains and lock the more extended conformation exerted by the pre‐stretch, enabling the construction of 3D‐printed hydrogel structures with high orientation. The equilibrated anisotropic hydrogel filaments with a water content of 50–60 wt.% exhibit outstanding mechanical properties (tensile strength: 9–44 MPa; elongation at break: 120–668%; Young's modulus: 7–62 MPa; toughness: 26–52 MJ m−3). 3D‐printed anisotropic hydrogel structures with high mechanical performance show demonstrated potential as loading‐bearing structures and electrodes of flexible triboelectric nanogenerators for versatile human motion sensing.