Mechanical enhancement of graphene oxide-filled chitosan-based composite hydrogels by multiple mechanisms

Chitosan (CS) has become a favorable choice for synthesizing hydrogels due to its hydrophilic and biocompatible nature. However, achieving robust CS-based hydrogels remains challenging. Herein, we propose a multiple mechanisms-based network design for mechanical enhancement in CS-based double-network (DN) composite hydrogels. In the DN composite gels, graphene oxide-filled CS-based network serves as the first network and polyacrylamide network is the second network. The multi-structure of the first network enhances its energy dissipation capacity; when combining with the second network to form DN structure, the coupling effect between the multiple mechanisms-based networks allows for much more energy dissipation, enabling synergistic enhancement in mechanical properties of the DN composite gels. By regulating the mechanics, we further explore the role of the individual networks. The results indicate that both the individual networks are essential: The first network primarily contributes to the energy dissipation, while the second network plays a role to the synergistic enhancement in the DN composite gels. This work provides an effective reinforcing strategy for CS-based composite hydrogels.