Determination of the concentration of single-walled carbon nanotubes in aqueous dispersions using UV- Visible absorption spectroscopy Academic Article uri icon

abstract

  • Stable, homogeneous, aqueous dispersions of single-walled carbon nanotubes (SWNTs) are prepared by nonspecific physical adsorption of surfactants enhanced by sonication. Upon centrifugation, supernatant and precipitate phases are obtained. The initial weights of the SWNTs and the surfactant are divided between these two phases, and the respective SWNT concentration in each phase is unknown. The focus of this work is on the determination of the true concentration of raw, exfoliated HiPCO SWNTs in the supernatant phase. A UV−visible absorption-based approach is suggested for a direct measurement of the SWNT and the surfactant concentration in the supernatant. UV−visible absorbance spectra of SWNTs−surfactant dispersions and surfactants alone reveal that the intensity of a certain peak, attributed to the π-plasmon resonance absorption, is unaffected by the presence of most surfactants. A calibration plot is then made by monitoring the intensity of the peak as a function of the true concentration of the exfol...

publication date

  • January 1, 2006