Mechanical properties of gelatin/polyacrylamide/graphene oxide nanocomposite double-network hydrogels

Gelatin/polyacrylamide/graphene oxide nanocomposite double-network hydrogels (Gelatin/PAAm/GO NC-DN gels) were prepared by in situ free radical polymerization. Their structure and properties were systematically characterized by X-ray diffraction (XRD), Raman spectroscopy, swelling experiments, scanning electron microscopy (SEM) and tensile tests. The results reveal that the GO nanosheets are significantly exfoliated in the gel matrix, serving as multi-functional cross-linkers in the NC-DN gels. At an optimal condition, Gelatin/PAAm/GO NC-DN gel demonstrates an excellent mechanical properties of an elastic modulus (E) of 187.3 kPa, a fractured stress (σf) of 0.324 MPa), a fractured strain (εf) of 45.5 mm/mm and a fractured energy (W) of 10.18 MJ/m3. More interestingly, the gels show a large hysteresis loop, softening phenomenon and self-recovery properties. This work deepens the understandings of the effect of nanomaterials on the mechanical properties of DN gels.