Poly(aniline-2-sulfonic acid) modified multiwalled carbon nanotubes with good aqueous dispersibility.

Poly(aniline-2-sulfonic acid) (PASA)-modified multiwalled carbon nanotubes (MWNTs) were prepared by in situ oxidative polymerization. HRTEM images show that the PASA-modified MWNTs (PASANTs) are core (MWNT)-shell (PASA) tubular structures with a shell thickness of several nanometers. The strong interaction between the surface of the MWNTs and the conjugated structure of the PASA shell layer was proven by FTIR spectra. It was found that the aqueous dispersibility and dispersion stability of PASANTs were significantly improved compared to those of the raw MWNTs. Furthermore, when the PASA content is greater than 30 wt%, no precipitation is found for the dispersions of modified MWNTs after sedimentation for 500 h, exhibiting an excellent stability. The electrical conductivity of these modified MWNTs is 2-5 times higher than that of raw MWNTs and is 10(3) times higher than that of PASA.