Highly Stretchable Nanocomposite Hydrogels with Outstanding Antifatigue Fracture Based on Robust Noncovalent Interactions for Wound Healing

Stable mechanical properties under cyclic mechanical loads are critical for the applications of hydrogels in flexible electronics and tissue engineering. However, most existing tough hydrogels still face obvious notch sensitivity and suffer from fatigue fracture under continuous load. Designing hydrogels with multifunctional properties, such as high stretchability, toughness, and excellent antifatigue fracture, through a facile strategy is on demand. In this work, the nanocomposite hydrogels with comprehensive mechanical properties were prepared by one-pot polymerization of acrylamide (AM), isocyanoethyl methacrylate-glutamine (IEM-Gln), and Laponite XLG nanosheets. Owing to the potent hydrogen bonds formed by urea groups in IEM-Gln and hydrogen-bonding interaction between the polymer chain and nanoclays, the presented nanocomposite hydrogels displayed excellent mechanical properties (tensile strength of 160 kPa, stretchability of 2600%, compressive strength of 2.3 MPa, and toughness of 3300 J/m2). It was noteworthy that the hydrogels exhibited excellent notch insensitivity and fatigue fracture resistance, and even after 50 cycles, there was no measurable crack propagation observed. In addition, the introduction of clay nanosheets into the gelation system endowed the composite hydrogels with outstanding hemostatic activity and tissue adhesiveness. The nanocomposite hydrogels could not only reduce the skin tension of the wound tissue by their high tensile properties but also accelerate hemostasis in the first stage of wound healing, both of which led to the fast healing of skin wound in mice.