Effect of surfactant adsorption on multi-walled carbon nanotubes dispersion

Abstract

Carbon nanotubes (CNTs) have attracted particular concern of researchers throughout the world due to their exceptional electronic, thermal, optical and mechanical properties for many applications. To obtain advantages of these properties, CNTs should have a high degree of individualization as well as homogeneous distribution. However, CNTs normally form agglomerates and inhomogeneous dispersion because of strong van de Waals interactions. One of the approaches to disperse them is non-covalent modification by using surfactant adsorption. The purpose of this work was to relate the adsorption behaviour of surfactants on multi-walled carbon nanotubes (MWCNTs) and activated carbons, and MWCNTs dispersion. The effect of surfactant concentration and the molecular structure of surfactants on the carbonaceous adsorbent in solution were investigated. In this study, sodium dodecyl benzene sulfonate (SDBS), cetylpyridinium chloride (CPC) and polyoxyethylene octyl phenyl ether (OP(EOL)10) were used as anionic, cationic and non-ionic surfactants, respectively. The adsorbed amount of surfactants on MWCNTs and activated carbon showed an order of SDBS > OP(EO)10 >and CPC > SDBS > OP(EO)10, respectively, as results from the different head group, tail length and charge. Moreover, the different dispersions of MWCNTs various concentration were also affected by the charge and alkyl chain length of surfactant.