Dispersion of multiwalled carbon nanotubes (MWCNTs) by ionic liquid-based Gemini pyrrolidinium surfactants in aqueous solution

• DOI: 10.1007/s00396-011-2500-2
• Publication Date: 2011-09-06T17:05:03Z
• Authors: Shaohua Zhang; Fei Lu; Liqiang Zheng
• Keywords: 01 natural sciences; 0104 chemical sciences

Gemini pyrrolidinium surfactants ([C n py-4-C n py][Br2]) are a new kind of ionic liquid-based Gemini surfactants. Multiwalled carbon nanotubes (MWCNTs) can be dispersed effectively in [C n py-4-C n py][Br2] aqueous solution. The resulting MWCNT suspensions are stable for more than 1 month, and no precipitation is observed. Ultraviolet–visible–near infrared (UV–Vis–NIR) spectra are performed to determine the dispersion of MWCNTs and the optimal concentration (C opt) of [C n py-4-C n py][Br2]. Compared with C n MPB, [C n py-4-C n py][Br2] is more effective in dispersing MWCNTs. It was also observed that [C n py-4-C n py][Br2] with a longer hydrocarbon chain displays a stronger dispersion ability. The adsorption of [C n py-4-C n py][Br2] on MWCNTs is investigated by zeta-potential and surface tension measurements. The zeta-potential results show that MWCNTs dispersed in [C n py-4-C n py][Br2] aqueous solution have relatively high positive charges. It is the electrostatic repulsion force between the MWCNTs which makes them stable. Furthermore, a possible dispersion mechanism is proposed.