Functionalization of carbon nanotubes with derivatized polyimide

Single-walled and multiple-walled carbon nanotubes were functionalized with derivatized polyimide for the homogeneous dispersion of the nanotubes. For the functionalization, the nanotube-bound carboxylic acids derived from the surface defects were targeted for esterification reactions with pendant hydroxyl groups in the derivatized polyimide. The functionalized nanotube samples, readily soluble in several common organic solvents, were thoroughly characterized by a series of instrumental techniques including NMR in both solution phase and solid state, optical absorption, Raman, thermogravimetric analysis, and microscopy methods. The results were consistent with well-dispersed nanotubes functionalized by the polyimide, and also with the expectation that the nanotube electronic properties were largely preserved in the specific mode of functionalization. The presumed formation of ester linkages in the functionalized samples was supported by the results from chemical defunctionalization. The potential applications of the polyimide-functionalized carbon nanotubes and the demonstrated functionalization strategy are discussed.