Sonication-driven dispersion of multiwalled carbon nanotubes in water with the aid of Na+-montmorillonite

Abstract

The poor dispersibility of multiwalled carbon nanotubes (MWNTs) in aqueous solvents is a serious obstacle to give full play to the excellent properties of MWNTs. How to effectively disperse MWNTs has become an urgent problem to be solved. Therefore, the addition of tertiary phase became necessary to promote such dispersion. In the present work, the sonication-driven dispersion of multi-wall carbon nanotubes (MWNTs) in aqueous Na+-montmorillonite (MMT) solution has been investigated with the help of UV-vis spectroscopy, particle agglomeration size and Transmission Electron Microscopy (TEM). The impact of ultrasonic power and time as well as MMT/MWNTs ratio on the dispersion of MWNTs was discussed. It was observed that sonication at 240 W for 40 min at MMT/MWNTs weight ratio of 2 resulted in efficient dispersion and formation of stabilized suspensions of individual nanotubes. The ultrasound provided high local shears to overcome the van der Waals interactions between tubes and lead to MWNTs debundling, which facilitate adsorption and immobilization of MMT on the surface of the MWNTs, preventing re-aggregation of MWNTs.