Developing super tough gelatin-based hydrogels by incorporating linear poly(methacrylic acid) to facilitate sacrificial hydrogen bonding.

Mechanically robust protein-based hydrogels are strongly desired but their construction remains a significant challenge. In this work, gelatin, together with methacrylic acid, is used to construct a novel hydrogen-bonded hydrogel through a facile low-temperature polymerization and a subsequent dry-swell process. The obtained gel is extremely stiff and tough with a high Young's modulus and a fracture energy of 11 MPa and 8.5 kJ m, respectively, which are comparable to the performance of tough synthetic hydrogels, rubber, cartilage, and skin. These gels also show recovery and healing properties as well as biocompatibility and stability in physiological saline solutions. The gel is easy to prepare and exhibits a wide range of functional properties, making it a promising load-bearing material for medical applications.