ABSTRACT
Carbon nanotubes (CNTs) in their as-produced forms are dif“cult to disperse and dissolve in water or organic media, and they exhibit extremely high resistance to wetting. Dif“culties also arise from incorporating the insoluble nanotubes into polymers when fabricating composites. This is because the carbon atoms on CNT walls are chemically stable due to the aromatic nature of the bonding. As a result, the reinforcing CNTs interact with the surrounding polymer matrix, mainly through van der Waals interactions, which may not provide an ef“cient load transfer across the CNT/matrix interface. It is known that the performance of a CNT/polymer nanocomposite depends critically on the dispersion of CNTs and the interfacial interactions between the CNTs and polymer. These challenges demand development of effective methods to modify the surface properties of CNTs. A suitable functionalization via the physical or chemical attachment of functionalities onto the CNT surface represents a strategy not only for improving CNT dispersion, solubility, and processability, but also for allowing strong interfacial interactions to take place between the CNTs and the polymer matrix. The endowed functionalities on CNTs can also be used to tailor the interactions of CNTs with other entities besides polymers, such as a solvent, biomolecules, and other nanoparticles. In addition, functionalized CNTs may exhibit mechanical or electrical properties that are different from those of pristine CNTs, and thus may be utilized for “ne-tuning the chemistry and physics of CNTs1. Therefore, the functionalization of CNTs has been an attractive target for synthetic chemists and materials scientists for a long time.
