Small organic molecules act as a trigger in an unzippering mechanism to facilitate carbon nanotube dispersion

In binary dispersing agents system, the contribution and roles of different sized molecules to carbon nanotubes (CNTs) dispersion remain unclear, which hinders the understanding of the environmental behaviour and risks of CNTs. This study compared the dispersion of CNTs by m-nitrobenzoic acid (NBA), trans-cinnamic acid (TCA), tannic acid (TA), and their mixtures. The dispersion efficiency of CNTs significantly reduced with the increased solid-phase concentration (Qe) of TA due to the adsorption of TA on newly exposed CNTs surfaces. However, the CNTs dispersion efficiency by NBA or TCA was independent of Qe because the dispersed CNTs surface was completely occupied by NBA or TCA without newexposed sites available for subsequent adsorption. The mixture of NBA or TCA with TA significantly enhanced the dispersion efficiency of CNTs, indicating a synergistic effect of CNTs dispersion. The addition of NBA or TCA decreased the hydrodynamic diameter of CNTs dispersed by TA, which indicated that NBA or TCA facilitated TA wedging into CNTs bundles for more complete separation of CNTs. This study highlighted the triggering effect of small molecules in the unzippering mechanismfor improving the dispersing efficiency of CNTs by large molecules. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study compared the dispersion of carbon nanotubes (CNTs) by different molecules and found some interesting results: TA affects the dispersion efficiency of CNTs; NBA or TCA are not affected by Qe in their dispersion efficiency of CNTs; mixtures of NBA or TCA with TA can enhance the dispersion efficiency of CNTs.