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Keywords:

  • graphene oxide;
  • graphene oxide multilayered structures;
  • graphene oxide polymer nanocomposites;
  • ionic graphene oxides

Abstract

The chemical surface modification of graphene and graphene oxide materials is a burgeoning area of investigation. We report the preparation of new ionic forms of graphene oxide by wet chemical modification and metathesis reactions. Graphene oxide (GO) was prepared by a modified Hummers method and functionalized to form cationic and anionic species. The former were prepared via nucleophilic substitution of alkyl amines at the epoxy and hydroxyl groups on the GO while the latter, consisting of sulfonated GO, was prepared via an aryl diazonium salt. The functionalized graphene oxide sheets consist of quaternary ammonium ion substituted GO, GO+, with Cl- or I- as counter ion and sulfonated GO, GO-, with H+, Ba2+ or tetraphenylphosphonium (TPP+) ion as counter ions. The addition reaction between GO+ and GO- in aqueous solution by metathesis to form a black [GO+][GO-] precipitate was also investigated. Materials were characterized by XRD, FTIR, Raman, STEM and TEM/HRTEM. Chemically modified graphene and graphene oxides are expected to facilitate further understanding of the chemistry and physics of graphene materials in general and contribute to the formation and further understanding of advanced hybrid graphene and graphene oxide polymer nanocomposites.1,2