Zinc ions enhanced nacre-like chitosan/graphene oxide composite film with superior mechanical and shape memory properties

Bio-inspired by the hierarchical structure and remarkable mechanical properties of natural nacre, nacre-like N-succinyl chitosan (NSC)-graphene oxide (GO) composite film was fabricated via zinc ion cross-linking and evaporation process. NSC and GO were used as the building “mortar and bricks,” which rapidly self-assembled into composite hydrogel (NSC/GO-Zn) via zinc ions cross-linking, and the hierarchical NSC/GO-Zn composite film was obtained thereafter by evaporation. A series of NSC/GO-Zn composite films with different GO concentrations was fabricated with the layered structure, as confirmed by scanning electron microscopy. Zinc ion-enhanced hierarchical NSC/GO-Zn composite film exhibited remarkable mechanical properties (strength of 212.6   ±   10.1   MPa and toughness of 2.51   ±   0.08   MJ·m −3 ). Unique shape memory response to alcohols was demonstrated by the composite film due to the presence of the chitosan, which has a significant ability to desorb/absorb water. Furthermore, a remarkable broad-spectrum bactericidal property of the NSC/GO-Zn composite film was observed through E. coli and S. aureus exposure. These features indicated that NSC/GO-Zn composite film has inherent properties that can be used in protection, aerospace, and biological materials.