Mechanically Robust Polyacrylamide Composite Hydrogel Achieved by Integrating Lamellar Montmorillonite and Chitosan Microcrystalline Structure into Covalently Cross-linked Network

Hydrogels have been attracting much attention on account of their soft and wet nature but inherently poor and unbalanced mechanical performance severely limits their applications. Herein, we reported a strategy to fabricate polyacrylamide/chitosan/montmorillonite nanocomposite hydrogels by simultaneously introducing lamellar montmorillonite and chitosan microcrystalline structure via a facile and universal two-step method composed of in situ free radical polymerization and alkali treatment . The incorporation of two-dimensional nanoclay and chitosan microcrystalline structure into polyacrylamide network synergistically facilitated the formation of robust and uniform polymer architecture through physical interactions and thus significantly improved the mechanical behavior. As a result, the satisfactory mechanical properties of the optimal nanocomposite hydrogels were achieved at a relative high water content (80 wt %), including a superior tensile strength of 1.91 MPa, high tensile strain of 1005%, and exceptionally great toughness of 14.16 MJ·m–3, respectively. Furthermore, they also possessed excellent compressive properties assessed from cyclic tests. On the basis of the structural evolution observation and analysis, a possible strengthening mechanism for enhanced mechanical properties was discussed and proposed. This high-performance nanocomposite hydrogel shows great potential as a promising candidate for structural or load-bearing materials.