Preparation And Properties Of Ternary Nanocomposite Based On Graphene

Graphene oxide and graphene exhibit great prospects in the areas of electrode materials, composite filler, biomaterials, and adsorption materials because of their large specific surface area, extraordinary mechanical, electrical and thermal properties. However, the defects of their poor dispersion lead to a great limitation to their applications of ideal reinforcing agents for their polymer composites. In this thesis, graphene oxide was prepared via an airtight oxidation reaction, then two kinds of ternary nanocomposite, graphene oxide/lignosulfonate/polyaniline and graphene/polyaniline/sulfonic polyaniline, were fabricated through modification of graphene oxide by water-soluble sulfonic polymer and conductive polymer polyaniline in order to improve the dispersity of graphene in the composites and properties of the composites.Firstly, graphene oxide was prepared by an airtight oxidation reaction with expansible graphite as a raw material, and then graphene was prepared via ammonia-hydrazine mixture reduction reaction. The morphologies and structures of graphene oxide and graphene were characterized by using TEM, AFM, FT-IR, Raman, UV-vis, XRD and TGA techniques. The results displayed that high quality graphene oxide and graphene nanosheets with an average area of 1 μm2 and 1-2 layers were obtained; the results also revealed that the thickness of graphene oxide sheet was about 1.5 nm and the graphene sheet was about 0.6 nm.Besides, graphene oxide/lignosulfonate/polyaniline (GO-LS-PANI) ternary nanocomposite was prepared via an in-situ static polymerization of aniline (ANI) in the presences of graphene oxide and lignosulfonate. The morphology and structure of the GO-LS-PANI ternary nanocomposite were characterized by FE-SEM, TEM, FT-IR, UV-vis, XRD and EA techniques. The results showed that polyaniline nanofibers with an average diameter of 50 nm were covered uniformly on the surface of graphene oxide nanosheets. Then, the adsorption properties of Pb2+ and methylene blue (MB) onto the GO-LS-PANI ternary nanocomposite were studied. The GO-LS-PANI ternary nanocomposite exhibited a maximum adsorption capacity as high as 216.4 mg g-1 for Pb2+ when the initial pH value was 5.0 and the adsorption temperature was 30℃; the GO-LS-PANI ternary nanocomposite has a maximum adsorption capacity as high as 26.3 mg g-1 for MB when the initial pH value was 7.0 and the adsorption temperature was 30℃. Moreover, the adsorption processes of Pb2+ and MB onto the GO-LS-PANI ternary nanocomposite agreed well with the pseudo-second-order kinetic equation and the Langmuir isotherm models.Finally, a ternary nanocomposite, graphene/polyaniline/sulfonic polyaniline (GPSP), was successfully prepared by in-situ oxidation copolymerization of ANI with diphenylamine-4-sulfonic acid (SP) in the presence of graphene oxide, followed by the chemical reduction reaction and using hydrazine hydrate as a reductant. The morphology and structure of the GPSP ternary nanocomposite were characterized by FE-SEM, TEM, FT-IR, UV-vis. XRD and TGA techniques. The results revealed that a hierarchical GPSP with a regular structure was obtained, the surface of graphene nanosheets was covered with poly(ANI-co-SP) nanoparticles with an average diameter of 30 nm. The electrochemical performance of GPSP ternary nanocomposite was further investigated. The specific capacitance of GPSP ternary nanocomposite reached 1111 F g-1 at a current density of 0.5 A g" Moreover, from the results of cycle stability performance of electrode materials, it was found that at a current density of 1 A g-1, the specific capacitance of GPSP ternary nanocomposite still retained 504 F g-1 after 500 charge/discharge cycle.