Carbon Nanotubes Functionalized With Polymers And Studies On Their Properties

Carbon nanotubes have been an area of intense research due to its unique structural and superior properties in numerous areas,such as m remarkable strength and high thermal and electrical conductivities.Nevertheless,the problem of insolubility in solvents and process ability duo to strong intertube Van der Waals attraction remains a severe limitation to the extensive use.The functionalization of carbon nanotubes is a vital tool in tailoring their properities and engineering devices,and many efforts have been undertaken with respect to this functionalization.Organic covalent modification of carbon nanotubes is the primary content in this thesis.Some novel well-defined graft copolymer with carbon nanotubes as the main backbone were successfully prepared through different synthesis ways and were characterized by FTIR,TEM and TGA etc.1.The chemical oxidation in a mixture of concentrated acids was used to modify carbon nanotubes(CNTs).After treatment,stable homogeneous dispersions of CNTs were prepared.Following the oxidation pretreatment,acyl chloride groups were introduced to the carbon nanotubes via reacting with sulfurous oxychloride and hydroxyl groups were introduced via ethylene glycol.The result showed that it introduced active functional groups while keeping the inherent properties of CNTs as much as possible.The modified CNTs were characterized by TEM and FTIR spectra.The method presented here was useful for further functionalization and application of CNTs.2.Carbon nanotubes with hydroxyl groups were used to synthesize graft copolymer MWNT-g-PAN through hydroxyl-functionalized carbon nanotubes/Ce⁴⁺,which was used as a redox system.The acrylonitrile(AN) was initiated by free radical to get the aim. As-prepared functionalized Multi-walled carbon nanotubes(MWNTs) were characterized with FTIR.The results proved the existence of chemical bonds between nanotubes and polymer.The dispersion experiments showed that the dispersion of the MWNT-COOH and MWNT-OH had been improved greatly in water and the MWNT-g-PAN had very good solubility in dimethylformamide(DMF). 3.The acids-treated carbon nanotubes were used to react with polyethylene glycol(PEG) with two hydroxyl groups and poly(EO-co-Gly) with several hydroxyl groups respectively,through removing off water.The prepared functionalized MWNTs were characterized with FTIR,TGA etc.The nonisothermal crystallization kinetics of MWNT-g-PEG was studied.The results indicated,at higher MWNTs content there was a dramatic reduction in crystallization process,with a lower crystallization velocity compared with pure PEG.4.The functionalized Multi-walled carbon nanotubes(MWNTs),which were synthesized by the reaction between 4-Hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (HO-TEMPO) and carboxyl groups on the MWNTs,were grafted with polystyrene chains.The prepared polystyrene chain was synthesized by the ATRP method.The soluble grafted MWNTs were obtained,indicating that the coupling was efficient.FTIR, GPC,¹H-NMR,TEM and TGA were used to determine the chemical structure, morphology,and the grafted PS quantities of the resulting products.According to the TGA values,it could be estimated that the graft density of polystyrene was that there was one chain per 972 carbon atoms on the surface of carbon nanotubes.TEM images of the samples provided direct evidence for the MWNTs coated with polymer layer.