Surface modification of graphene oxide for preparing self-healing nanocomposite hydrogels

In this work, graphene oxide (GO) and vinyl modified GO (V-GO)-based nanocomposite hydrogels with improved mechanical property and self-healing ability have been synthesized and characterized. GO first was synthesized by modified Hummer's method using graphite powder and then functionalized with vinyl groups by using (3-mercaptopropyl) trimethoxysilane (MPTS) via silanization method. The GO and V-GO nanoparticles were characterized by FT-IR, UV-vis spectroscopy, SEM, and dynamic light scattering technique (DLS). Hydrogels were obtained by in-situ free-radical polymerizations of acrylamide (AAm) and [3-(methacryloylamino)propyl] trimethylammonium chloride (MAPTAC) monomers in the presence of GO and V-GO nanoparticles. The effects of the amount of GO and V-GO on the gelation profile and viscoelastic characteristics of the hydrogels were studied. The pH-responsive action, swelling behavior, and swelling kinetics of the hydrogels with various GO and V-GO contents were also evaluated. The mechanical performance of nanocomposite cationic hydrogels prepared with GO and V-GO nanosheets was compared to the neat AAm-MAPTAC hydrogels. The self-healing ability of the hydrogels were elucidated as a function of the amount of GO and V-GO nanosheets bound to the polymer network by physical interactions and chemical cross-links, respectively.