Stabilization of pristine and oxidized carbon nanotubes dispersions in acidic and alkaline solutions

The possibility of stabilizing aqueous dispersions of carbon nanotubes (CNTs) using phenol-formaldehyde resin (PFR) and aminocumulene (AC) is shown. The preliminary oxidation of CNTs contributes to their higher solubility in the presence of these stabilizing agents. The concentration of pristine and oxidized CNTs in weakly alkaline solutions containing 2.5 g/L of PFR is 3.0 and 11.4 g/L, respectively. AC promotes the formation of stable dispersions in acidic media with the concentrations of pristine and oxidized CNTs, respectively, 3.3 and 20.4 g/L. A decrease in the effective sizes of agglomerates of both pristine and oxidized CNTs in the presence of PFR and AC has been shown by dynamic light scattering method. According to TG/DSC analysis and Raman spectroscopy data, it was concluded that the oxygen-containing groups of oxidized CNTs interact with the surfactants used. Schemes for the formation of hydrogen and chemical bonds between CNTs and PFR or AC were proposed, which made it possible to explain the effect of dispersion.