Observation of carbon nanotube and clay micellelike microstructures with dual dispersion property.

ABSTRACT

Micellar microstructures of carbon nanotubes (CNTs) with clay platelets were formed by physically pulverizing both materials in powder form. The resultant CNT-clay mixtures were enabled to decrease the level of aggregation of the CNTs from their original state in water as well as in organic mediums including toluene, dimethylformamide, and ethanol. The presence of clay significantly enhanced the CNT dispersion in the following trend anionic synthetic fluorinated mica (300 x 300 x 1 nm(3)) > anionic sodium montmorillonite (80 x 80 x 1 nm(3)) > cationic layered double hydroxide (200 x 200 x 1 nm(3)). Both geometric dimensions and ionic charge could be the predominant factors for decreasing the CNT entanglement. The CNT-Mica demonstrated an amphiphilic property for dispersing in water and toluene, but in an irreversible manner. It is explained that the original CNT and clay's noncovalent bonding forces are randomized during the contact with solvent. The formation of micellelike microstructures, resembling oil-in-water and water-in-oil surfactants, was proposed. Ultraviolet-visible absorbance and transmission electronic microscopy have verified the existence of two different microstructures, which also exhibited differences in thermal stability (600 vs 650 degrees C onset temperature) by thermal gravimetric analysis as well as electrical conductivity (10(-4) vs 10(-6) S/cm).