Water-soluble multiwalled carbon nanotubes functionalized with sulfonated polyaniline.

Multiwalled carbon nanotubes (MWNTs) functionalized with a water-soluble conducting polymer, sulfonated polyaniline (SPAN), were prepared by in situ polymerization of aniline followed by sulfonation with chlorosulfonic acid in an inert solvent and by hydrolysis in water. Electron microscopy, laser Raman spectroscopy, X-ray photoelectron spectroscopy, and UV-vis absorption spectroscopy were employed to characterize the morphology and chemical structure of the resulting product. The results show that the quinonoid structure of SPAN preferentially interacts with the nanotubes and is stabilized by strong pi-pi interaction between two components. The structure of MWNTs was not perturbed by the incorporation of SPAN, since the pi-pi interaction between MWNTs and SPAN is much weaker in comparison to that of the carbon covalent bond. The SPAN functionalized MWNTs are highly dispersible in water, thus opening new possibilities for their prospective technological applications.