Functionalizing multi-walled carbon nanotubes with poly(oxyalkylene)-amidoamines

Multi-walled carbon nanotubes were functionalized by sequential HNO 3 oxidation and amidation with high-molecular-weight poly(oxyalkylene)-amines (400–2000 g mol −1 ) as the modifying agents. These nanotube-tethering organic portions include two types of polyether backbone, hydrophobic poly(oxypropylene) (POP) and hydrophilic poly(oxyethylene) (POE). By varying these hydrophilic or hydrophobic structures and their lengths, the organically modified nanotubes can be tailored to have different dispersing properties, either in water or in organic solvents. Homogeneous dispersion further allowed the observation of the detailed morphology of individual nanotubes and their aggregated forms by using atomic force microscopy and field emission-scanning electron microscopy analyses.