High mechanical properties nanocomposite hydrogel achieved based on montmorillonite and tailored microgel suspensions reinforcing polyacryamide networks

Hydrogels have attracted much attention because of their softness and water retention ability, but their poor mechanical properties have severely limited their application in various aspects. Herein, we reported a strategy to fabricate polyacrylamide/montmorillonite nanocomposite hydrogel by introducing montmorillonite via a facile and universal two-step method composed of microgel suspension system and in situ free radical polymerization. Compared with microgel, microgel suspension is simpler to prepare and better dispersed in hydrogels, which it could act as physical crosslinking points, interpenetrate with polyacrylamide networks embedded, and serve as sacrifical bonds to strengthen the hydrogels. Simultaneously, montmorillonite synergistically facilitated the formation of a robust and uniform polymer structure through the interaction of hydrogen bonds and polyacrylamide networks, resulting in significant improvements in mechanical properties. As a result, the satisfactory mechanical properties of the nanocomposite hydrogels are achieved at a relative high water content (80 wt%), including a superior compressive strength (95% deformation) of 37.96 MPa, tensile strength of 311.1 ± 8.2 kPa, elongation at break of 316.5 ± 21.1%, Young's modulus of 165.8 ± 7.5 kPa, and excellent toughness of 644.1 ± 21.8 kJ/m3, respectively. In addition, it was found that the hydrogel had excellent cycle compression stability through 10 cycles of loading and unloading at 80% strain. These new high-performance nanocomposite hydrogels are expected to be used in the fields of structural or load-bearing materials.