Preparation, Modification And Application Of Carbon Nanoubes And Graphene

Carbon is a basic and important element on earth. Carbon nanostructures in zero, one and two dimensions offer great potential in a broad range of applications. In this paper, we studied the preparation, modification and primary application of two carbon nanomaterials:carbon nanotubes (CNTs) and graphene. The detail research contents and results are summarized as follows:(1) Through series of steps, the raw material of CNTs were purified and carboxyl and hydroxyl were introduced, which greatly improved solubility and stability of CNTs dispersion. Functionalization of CNTs with amine groups was achieved after such steps as carboxylation, acylation and amidation; The grafting of polystyrene-polyacrylamide block copolymer to single walled carbon nanotubes (SWCNTs) was achieved by in situ living free radical polymerization. The resulting dispersions were stable and had homogeneous dark ink-like appearance, consisting mainly of long isolated nanotubes and thin bundles; Anionic and cationic CNTs/polyelectrolytes, prepared by covalent modification of CNTs with poly(acrylic acid) and poly(acrylamide), were used for the layer-by-layer (LBL) self-assembly of CNTs on different substrates, such as glass and PS colloids; Nanotube-reinforced epoxy composites were prepared by mixing amino-functionalized CNTs with epoxy resin. Differential scanning calorimetry, thermogravimetric analysis and bending tests were used to investigate the thermal and mechanical properties of the composites. The results showed that different kinds of amino-functionalized CNTs would have different effects on the thermal and mechanical properties of the composites; Catalyst of Pt-Co supported on single-walled carbon nanotubes (SWCNTs) is prepared using mixed reducing agents. Under same Pt loading mass and experimental conditions, the SWCNTs-Pt-Co catalyst showed higher electro catalytic activity and improved resistance to CO poisoning than the SWCNTs-Pt catalyst.(2) A massively scalable, fast and facile method for preparation of graphene oxide sheets (GOS) and graphene nanoplatelets was achieved. The basic strategy involved the preparation of graphite oxide (GO) from graphite through reaction with benzoyl peroxide, complete exfoliation of GO into GOS, followed by their in-situ reduction to individual graphene nanoplatelets. The mechanism of GOS producing is mainly the generation of oxygen-containing groups on graphene sheets; The grafting of polystyrene-polyacrylamide (PS-PAM) block copolymer to graphene nanoplatelets was achieved by in situ living free radical polymerization. This method is beneficial because the amphiphilic property of the block copolymer can help to stabilize graphene nanoplatelets in both polar and non-polar solvents; Organophilic chemically functionalized graphene (OCFG) sheets were achieved through such steps as complete exfoliation of GO into GOS, followed by reacting with 1-Bromobutane to get OCFG sheets; hydrophilic and organophilic chemically modified graphene sheets were prepared through a two-step diimide-activated amidation. The dispersions are homogeneous and exhibit long-term stability, which facilitate their combination with polymers to yield homogeneous composites; graphene nanoplatelets were self-assembled through LBL method. Anionic and cationic graphene-containing polyelectrolytes, prepared by covalent modification of graphene sheets with poly (acrylic acid) and poly (acryl amide), were used in the cyclic dispersion procedures; Magnetic GOS were prepared by attaching magnetic nanoparticles to GOS through high temperature reaction of ferric triacetylacetonate with GOS in 1-methyl-2-pyrrolidone; Catalyst of Pt-Co binding on GOS was prepared using mixed reducing agents and their activity in the electro-oxidation of methanol was studied. It was found that the presence of GOS leads to higher activity, which might be due to the increase of electrochemically accessible surface areas and easier charge-transfer at the interfaces. An in situ chemical synthesis approach was proposed to prepare Ag/chemically converted graphene (CCG) nanocomposites. The reducing process of GOS was accompanied by generation of Ag nanoparticles. Raman signals of CCG in such nanocomposites are greatly increased by the attached silver nanoparticles, displaying surface-enhanced Raman scattering activity. In addition, it was found that the antibacterial activity of Ag nanoparticle still exists, which is promising to be used as graphene-based biomaterials; GOS were functionalized by bovine serum albumin (BSA) via diimide-activated amidation under ambient conditions. The obtained GOS-BSA conjugates are highly water-soluble, forming brown-colored aqueous solutions. Results of cyclic volatammograms showed that the protein in the GOS-BSA conjugates retains its bioactivity.