Radiation functionalization of single- and multi-walled carbon nanotubes

Radiation functionalization was performed on single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) shortened by physical and chemical methods using γ-irradiation. FT-IR spectra of SWCNTs and MWCNTs functionalized with carboxylic acid units displayed the characteristic peaks of the carbonyl (ca. 1700 cm^-1) and hydroxyl groups (ca. 3400 cm ^-1). In the FT-IR spectra of SWCNTs and MWCNTs functionalized with sulfonic acid units, the characteristic peak at ca. 3400 cm^-1 was due to hydroxyl groups and that at ca. 1124 cm^-1 was due to sulfonic groups. From these results, the functionalization of the surfaces of SWCNTs and MWCNTs by the introduction of γ-irradiation was successful when using Triton X-100 as a dispersing agent in organic solvent.