Effect of non-ionic surfactants on the dispersion of multiwalled carbon nanotubes at high loading in ethanol

Abstract

The dispersion of highly concentrated multiwalled carbon nanotubes (MWNTs) in ethanol without polymer or covalent functionalization would generally facilitate the addition of MWNTs to a wide range of composite materials. To this end, suspensions of MWNTs in ethanol with various surfactants were prepared and their stabilities were evaluated. Non-ionic surfactants such as Triton X-100 and Tween 65 could suspend high-loading nanotubes in ethanol. MWNT suspensions in ethanol with Triton X-100 and Tween 65 initial supernatant concentrations of 1.0 g·L-1 were prepared and their concentrations were more than 0.50 and 0.35 g·L-1 after 240 h, respectively. These concentrations for MWNT suspensions, which are stable over the long term in ethanol without polymer or covalent functionalization, are higher than others reported in literature. The structural advantage of these non-ionic surfactant molecules for MWNT dispersion is discussed and a schematic representation is given to illustrate their adsorption on nanotube surfaces. The existence of surfactant molecules adsorbed on the nanotube surfaces was confirmed by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy(TEM). © Editorial office of Acta Physico-Chimica Sinica.