| Graphene sheets, two-dimensional one-atom-thick layers of sp2-bonded carbon, have attracted tremendous attention from the experimental and theoretical communities. It can form zero-dimensional fullerenes, one-dimensional carbon nanotube and three-dimensional graphite. Graphene has changed the opinion that two-dimensional material can not exist at room temperature. It has a wide application in the transistors, nano-electronic devices, batteries for the outstanding electrical, mechanical and thermal properties. In this thesis, a single-layer structure of graphene oxide was prepared by sonicating and two different types of nanocomposites based on graphene were respectively obtained with poly(vinyl alcohol) and chitosan.(1)By comparing thermal expansion and ultrasonication methods, it can be observed that pyrolytic graphite can not be exfoliated to single layer graphene. The chemically active groups were greatly reduced due to the thermal expansion process and thus the applications of graphene in polymer composites were limited. After sonicating, however, graphene oxide was exfoliated to single layer with the chemically active groups, which can find wide applications in polymer nanocomposites.(2) (PVA/GO)n ultrathin film composites were prepared via layer-by-layer (LBL) self-assembly technique. UV-vis and XRD results indicated that GO could readily form ordered ultrathin films with PVA at molecular level owing to strong hydrogen bonding interaction between them. High orientation of graphene oxide in PVA matrix was achieved through such a self-assembly. Therefore, it offers an approach to fabricate a plenty of composite films based on water-soluble polymers and graphene oxide.(3) Chitosan/graphene oxide composites were prepared by solution blending. TEM and tensile test results showed that the graphene oxide was well dispersed in chitosan. Tensile strength and modulus of the nanocomposites were significantly increased, while the elongation at break of the nanocomposites was decreased. |
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