Stimuli-Responsive Polymer Covalent Functionalization of Graphene Oxide by Ce(IV)-Induced Redox Polymerization

Stimuli-responsive polymers, poly(acrylic acid) and poly(N-isopropylacrylamide), were covalently grafted onto the surface of graphene oxide through a facile redox polymerization initiated by cerium ammonium nitrate in aqueous solution at mild temperature. Thermogravimetric and element analyses show that the graft ratio of polymers increased with the increase of feeding amount of monomers. Atomic force microscopy reveals that the size and morphology of graphene oxide are well retained after the redox polymerization, with the exception of being covered by a homogeneous layer of polymer. The covalently grafted poly(acrylic acid) and poly(N-isopropylacrylamide) afforded pH and thermal responsibility to graphene oxide, and the assemble disassemble behaviors of polymer-grafted graphene oxide in aqueous solution could be controlled by varying the pH or temperature of the solution, which provided a favorable strategy to handle the aqueous solution of graphene oxide.