Facile Construction of Gelatin/Polyacrylamide Acrylic Acid/Sodium Alginate-Based Triple-Network Composite Hydrogels with Excellent Mechanical Performances

Three-network hydrogels have a wide range of applications due to their different network structures and diverse cross-linking methods. In this work, a triple-network hydrogel strategy based on double network coordination and cross-linking is proposed, including gelatin (Gelatin) network, polyacrylamide acrylic acid (PAMAAc) network, and sodium alginate (SA) network. SA and AAc molecular chains contain a large amount of -COO-, which can coordinate with metal ions and generate a large number of dynamic coordination bonds. The hydrogel forms the PAMAAc network through free radical polymerization, and at the same time the interpenetrating cross-linked Gelatin network and SA network are formed through hydrogen bonding. In addition, the addition of metal ions realizes the coordination cross-linking of the double network in the hydrogel. Moreover, the prepared composite hydrogels exhibit good mechanical properties and self-recovery properties. It should be noted that the concentration of different metal ions and the time of coordination and crosslinking will affect the mechanical properties of the hydrogel. The current work provides an idea for preparing a three-network hydrogel with high compressive strength and fast self-recovery.