Electrophoretic Deposition of Carbon Nanotubes Using New Dispersing and Charging Agents

摘要: The dispersion of carbon nanotubes (CNTs) is of great importance in both industrial and academic areas. Various methods were proposed and investigated for the dispersion, including the use of surfactant and polymers as dispersing agents. However, such method requires relatively high dispersant concentrations. Polymers bring about bridging flocculation CNTs. Chemical modified CNTs have soluble groups in its structure and can be dissolved in water or ethanol. However, the functionalization process can cause the structure damages and hence the conductivity of CNTs is reduced. Therefore, new methods have to be explored to disperse CNTs with high efficiency and stability and less structure damages. The aromatic molecules can adsorb on the surface of CNTs by the π-π stacking mechanism. Because of the adsorption, the aggregation of CNTs can be broken and a homogeneous suspension can possibly be obtained. Pyrene was proved to be a good dispersant for CNTs in non-polar solvent for its adsorption on CNTs surface, which directly proves this mechanism. This mechanism can be used for choosing dispersing agent working in polar solvents, eg water and ethanol. Aromatic organic molecules with charged soluble groups can be used as dispersants for CNTs in polar solvents. And an example of this kind of molecules is pyrenebutyric acid (PBH), which has pyrene group for attaching CNTs and carboxylic acid for dissolving in water. Because PBH is insoluble in water, it has to be protonated using sodium hydroxide firstly and then the PB-works as dispersing agent for CNTs,(Fig. 1) so the dispersed CNTs is negatively charged and …