[2+1] cycloaddition for cross-linking SWCNTs

Using the nitrene reaction, two individual single-walled carbon nanotubes can be covalently connected inducing only few defects to the nanotube sidewall. With this functionalization method nanotubes can be linked within a bundle as well as between bundles. For systematic investigations, a series of linker molecules of different lengths were synthesized. By filtering and drying, a buckypaper of linked nanotubes was obtained. The paper of modified nanotubes shows a higher stability than a buckypaper of pristine material. After the impurities and unreacted nanotubes have been washed out, the remaining connected SWCNTs are insoluble in any solvent. This report represents the first results of linking nanotubes using this method. Characterization on a molecular scale was carried out using SEM, TEM, AFM, XPS, XRD and Raman spectroscopy. Spectroscopic methods and X-ray diffraction give clear evidence for the reaction of nitrenes with the nanotube sidewall. With microscopic methods the linkage of the nanotubes can be observed. (C) 2003 Elsevier Ltd. All rights reserved.