Hydrodynamic characterization of surfactant encapsulated carbon nanotubes using an analytical ultracentrifuge

Michael S. Arnold, Jin Suntivich, Samuel I. Stupp, Mark C. Hersam*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

104 Scopus citations


The hydrodynamic properties of surfactant encapsulated single-walled carbon nanotubes (SWNTs) have been characterized by optically measuring their spatial and temporal redistribution in situ in an analytical ultracentrifuge. The measured redistribution profiles are fit to the Lamm equation, thus determining the sedimentation, diffusion, and hydrodynamic frictional coefficients of the surfactant encapsulated SWNTs. For sodium cholate encapsulated SWNTs, we demonstrate that the technique of analytical ultracentrifugation can be utilized to determine the linear packing density of surfactant molecules along the length of the SWNTs, 3.6 ± 0.8 nm-1, and the anhydrous molar volume of the surfactant molecules on the SWNT surfaces, 270 ± 20 cm3 mol-1. Additionally, analytical ultracentrifugation is used to measure and compare the sedimentation rates of bundled and isolated carbon nanotubes. This study should serve as a guide for designing centrifuge-based processing procedures for preparing samples of SWNTs for a wide variety of applications and studies. Additionally, the results obtained here should aid in understanding the hydrodynamic properties of SWNTs and the interactions between SWNTs and surfactants in aqueous solution.

Original languageEnglish (US)
Pages (from-to)2291-2300
Number of pages10
JournalACS nano
Issue number11
StatePublished - Nov 2008


  • Carbon nanotubes
  • Density
  • Diffusion
  • Hydrodynamic
  • Sedimentation
  • Surfactant encapsulated
  • Ultracentrifuge

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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