Mixed surfactant system for stable suspension of multiwalled carbon nanotubes

The dispersion stability of carbon nanotubes in water and organic solvents is a challenging task for their utilization in nanoscale devices. Multiwalled carbon nanotubes (MWNTs) have been tested with different chemical functionalities of the side groups for their dissolution in organic solvents. Herein, we investigated the dispersive effects achieved by surface-active agents on MWNTs. Dodecyl trimethylammonium bromide (DTAB) and sodium octanoate (SOCT) were found to form exceptionally stable MWNT dispersions. In this study, a novel method was developed to prepare highly dispersed MWNTs using the mixtures of cationic surfactant DTAB and anionic surfactant SOCT. Stable dispersions were obtained at low total surfactant concentration as compared to their concentration when used alone. Zeta potential was confirmed to understand the surface charge-related stability of the nanotubes solutions. The dispersion of MWNTs has been characterized by scanning electron microscopy (SEM). Raman spectroscopy and transmission electron microscopy (TEM) showed non-covalent interaction of MWNTs and surfactants. (C) 2010 Elsevier B.V. All rights reserved.This research work is sponsored by 'Higher Education Commission (HEC), Govt. Of Pakistan' under the scholarship program titled: MS Level Training in Korean Universities/Industry.; This study was also supported by a grant from the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Commerce, Industry and Energy, Republic of Korea