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

Abstract

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.