Web Release Date: January 4,
Large Populations of Individual Nanotubes in Surfactant-Based Dispersions without the Need for Ultracentrifugation
and
School of Physics, Trinity College Dublin, University of Dublin, Dublin 2, Ireland, and Centre for Research on Adaptive Nanostructures & Nanodevices, Trinity College Dublin, University of Dublin, Dublin 2, Ireland
Received: August 29, 2007
In Final Form: October 15, 2007
Abstract:
Stable dispersions of single-walled carbon nanotubes have been produced using the surfactant sodium
dodecylbenzene sulfonate (SDBS). Atomic force microscopy analysis shows that, on dilution of these
dispersions, the nanotubes exfoliate from bundles, resulting in a concentration-dependent bundle diameter
distribution which saturates at Drms 
2 nm for concentrations, CNT < 0.05 mg/mL. The total bundle number
density increases with concentration, saturating at ~6 bundles per 
m3 for CNT > 0.05 mg/mL. As the
concentration is reduced the number fraction of individual nanotubes grows, approaching 50% at low
concentration. In addition, partial concentrations of individual SWNTs approaching 0.01 mg/mL can be realized.
These values are far superior to those for solvent dispersions due to repulsion stabilization of the surfactant-coated nanotubes. These methods facilitate the preparation of high-quality nanotube dispersions without the
need for ultracentrifugation, thus significantly increasing the yield of dispersed nanotubes.
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