Advanced Lignin‐Based Hydrogels with Superior Stiffness, Toughness, and Sensing Capabilities

Abstract Hydrogels, known for their 3D polymer networks and high water content, are widely used in applications ranging from agriculture to tissue engineering and soft electronics. However, balancing toughness and stiffness in hydrogels remains a significant challenge due to the inverse relationship between these properties. In this study, a dual‐network hydrogel is developed composed of lignin/poly(N,N‐dimethylacrylamide) (PDMA) and sodium alginate/Ca²⁺ (SA/Ca²⁺) using a solvent exchange method. This hydrogel incorporates multi‐level energy dissipative structures, resulting in both high stiffness and toughness. Specifically, the DL/S_0.1Ca_0.5 hydrogel exhibited impressive mechanical performance, including a tensile stress of 3.7 MPa, a tensile strain of 1100%, and a tensile modulus of 8.7 MPa, along with remarkably high toughness of 97,000 J m⁻² and work of extension of 25 MJ m⁻³. Additionally, it demonstrates exceptional rupture and collision resistance, outstanding conductivity of 19.7 S m⁻¹, and high strain sensitivity with a gauge factor up to 7.78. These features highlight its potential for use in extreme sports protection and wearable sensors, representing a significant advancement in the development of multifunctional hydrogels.