High strength, tough and self-healing chitosan-based nanocomposite hydrogels based on the synergistic effects of hydrogen bond and coordination bond

In this study, we proposed a simple one-pot strategy to synthesize a fully physically cross-linked chitosan-based nanocomposite hydrogels through the construction of hydrogen bonds and metal-carboxylate coordination bonds within hydrogel networks, in which Al 3+ and hydroxyapatite acted as cross-linking points. FT-IR and XPS results confirmed that chitosan-based nanocomposite hydrogels were synthesized by the non-covalent interactions. pH-sensitivity, surface morphology and mechanical properties of the synthesized hydrogels can be regulated by the compositions. The resulting optimal sample exhibited three-dimensional structure, high tensile strength (379.5 kPa), and large elongation at break (18.6 mm/mm). The non-covalent interactions served as sacrificial bonds to dissipate energy during the deformation of the hydrogels, which improved significantly the toughness of the materials. Additionally, the multiple dynamically reversible non-covalent interactions not only made the materials have fast self-recovery capacity, but also gave the materials good self-healing ability. We expect that this facile strategy of incorporating the hydrogen bonds and coordination bonds may enrich the avenue in exploration of dynamic and tunable nanocomposite hydrogels to expand their potential applications in the biomedical field.