Study On Multi-walled Carbon Nanotubes Grafted By Hyperbranched Poly (Amine-ester)

Carbon nanotubes have high mechanical strength, unique optical properties and super adsorption capacity, so people pay more and more attention to it. But the poor dispersibility in the solvent limits their wide application and development. Surface functionalization of carbon nanotubes means introducting functional groups on the carbon nanotubes'surface to increase its dispersion in solvents, while also giving it a new performance.In this study, multi-walled carbon nanotubes were used as the raw material. Carbon nanotubes were purified by gas combining liquid method to remove the residual carbon impurities and the metal catalyst particles from them. XRD and TGA-DSC characterization show that the purification method is effective. Then the mixed acid was used to connect the carboxyl on the carbon nanotubes'surface. The "grafting from" method was used to "grow" hyperbranched macromolecules on the surface of carbon nanotubes and the "grafting to" method was used to graft hyperbranched polyurethane to the surface of carbon nanotubes. Functional carbon nanotubes were characterized by SEM, FTIR, TGA-DSC, XRD and acid-base titration methods. The results showed that the mixed acid oxidation can efficiently introduct carboxyl and hydroxyl on the surface of carbon nanotubes. By controling the reaction temperature and time, carbon nanotubes can be achieved without destroying its structure, and producing a large number of oxidation groups on its surface. The "grafting from" method, not only grafted hyperbranched macromolecules on its surface, but also "grew" macromolecules'area on its surface. The "grafting to" method can graft specific structure polymer on the surface of carbon nanotubes. Hyperbranched polymers have a variety of functional groups which not easy to wind. Hyperbranched polyurethane modified with carbon nanotubes can significantly improve its capacity of dispersion. Hydroxyl density of carbon nanotubes were 24.74 mmol/g, 20.04 mmol/g; solubility in water were 2.67, 2.49. Modification of carbon nanotubes can create conditions for further functionalization and application.