Probing Carbon Nanotube鈥揝urfactant Interactions with Two-Dimensional DOSY NMR

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• 作者：Tejas A. Shastry ; Adam J. Morris-Cohen ; Emily A. Weiss ; Mark C. Hersam
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：May 8, 2013
• 年：2013
• 卷：135
• 期：18
• 页码：6750-6753
• 全文大小：278K
• 年卷期：v.135,no.18(May 8, 2013)
• ISSN：1520-5126

文摘

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鈥搒urfactant complexes.