Dispersability of multiwalled carbon nanotubes (MWCNTs) in aqueous suspensions was investigated with gum arabic GA (anionic) and polydiallyldimethylammonium chloride (PDADMAC) cationic dispersants. The isoelectric point (iep) of MWCNTs was at pH 4.5. The surface charge of MWCNTs changed to highly negative and iep shifted to pH<1.5 with GA, whereas with PDADMAC highly positive and iep is shifted to pH 10.2. The interaction energy of MWCNTs with GA and PDADMAC was 9.79 and 10.35 RT unit, respectively. The higher interaction energy with PDADMAC shows more favorable interaction with them. Stabilization mechanism with GA is attributed mainly by electrostatic repulsive forces, whereas with PDADMAC, electrostatic and steric effect.
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