Probing carbon nanotube-surfactant interactions with two-dimensional DOSY NMR

Tejas A. Shastry, Adam J. Morris-Cohen, Emily A. Weiss*, Mark C. Hersam

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


Two-dimensional diffusion ordered spectroscopy (2D DOSY) NMR was used to probe the micellar structure of sodium dodecyl sulfate (SDS) and sodium cholate (SC) in aqueous solutions with and without semiconducting and metallic single-walled carbon nanotubes (SWCNTs). The solutions contain SDS and SC at weight ratios of 1:4 and 3:2, the ratios commonly used to isolate semiconducting and metallic SWCNTs through density gradient ultracentrifugation (DGU). These results show that the coverage of surfactant on the semiconducting and metallic SWCNTs is nearly identical in the 1:4 surfactant mixture, and a lower degree of bundling is responsible for the greater buoyancy of semiconducting SWCNTs. In the 3:2 surfactant mixture, the metallic SWCNTs are only encapsulated in SC while the semiconducting SWCNTs remain encapsulated in a poorly packed two-surfactant micelle, leading to a large buoyant density difference between the electronic species. This work provides insight into future directions to increase the purity of semiconducting and metallic SWCNTs sorted through DGU and demonstrates the utility of 2D DOSY NMR in probing SWCNT-surfactant complexes.

Original languageEnglish (US)
Pages (from-to)6750-6753
Number of pages4
JournalJournal of the American Chemical Society
Issue number18
StatePublished - May 8 2013

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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