Functionalization And Application Of Multi-walled Carbon Nanotubes

Nowadays, carbon nanotubes (CNTs) have attracted widespread attention and have gained continuous and promising applications due to their unique structure and excellent properties. However, the poor solubility and low dispersion performance have restricted the wide application of carbon nanotubes. Therefore, in order to improve the solubility and dispersion, the surface modification or functionalization of carbon nanotubes has become the research hotspot in the materials, physics and chemistry field.Although carbon nanotubes have high chemical stability, large surface area and outstanding mechanical properties, only very limited literatures concerned their use as a support for covalently bonded homogeneous catalysts. Inspired by high solubility of functionalization of carbon nanotubes, we have ignited an effort to explore, when the carbon nanotubes anchored homogeneous catalysts are soluble in the reaction medium, whether the catalytic activity was maintained in comparison with their homogeneous analogues. Herein, we present the synthesis and characterization of2,2,6,6-tetramethylepiperidine-l-oxyl (TEMPO) attached on the oxidized MWNTs, which was evaluated as heterogeneous and soluble catalysts for the oxidation of alcohols. To our delight, the soluble MWNTs-TEMPO catalyst proved to be effective and highly selective for the oxidation reaction of primary and secondary alcohols under standard Anelli’s condition. Additionally, we further investigated the substrate scope and recycling of the catalyst, as well as the effect of the solubility of the functionalized MWNTs on the catalytic activity.Recently, diverse chemical functionalizations for carbon nanotubes have been developed to resolve the aggregates, which represent a severe hindrance for their excellent performances. Especially, the grafting of macromolecules has attracted great interest in the recent decades because it is a powerful strategy to enhance the solubility and minimize the degree of functionalization. In addition, their chemical affinity to engineering polymer matrices makes them an ideal candidate as an advanced filler material in nanocomposites in combination with strength and conductivity. Herein, we report functionalization of oxidized carbon nanotubes (MWNTs-COOH) with polycarbonates by means of surface-initiated immortal CO2and epoxides copolymerization, which was directly carried out in a single step by rapid and reversible chain transfer. The grafting modification provided stable dispersion of CNTs in a range of polar solvents, allowing the fabrication of highly conductive thin films. Moreover, the grafting CNTs were found to be compatible with PPC matrix to improve the mechanical properties.