Dielectrophoresis of surface conductance modulated single-walled carbon nanotubes using catanionic surfactants

Youngjin Kim, Seunghyun Hong, Sehun Jung, Michael S. Strano, Jaeboong Choi, Seunghyun Baik

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    63 Scopus citations


    Dielectrophoresis has received considerable attention for separating nanotubes according to electronic types. Here we examine the effects of surface conductivity of semiconducting single walled carbon nanotubes (SWNT), induced by ionic surfactants, on the sign of dielectrophoretic force. The crossover frequency of semiconducting SWNT increases rapidly as the conductivity ratio between the particle and medium increases, leading to an incomplete separation of ionic surfactant suspended SWNT at an electric field frequency of 10 MHz. To reduce the conductivity ratio, the surface charge of SWNT is neutralized by an equimolar mixture of anionic surfactant sodium dodecyl sulfate (SDS) and cationic surfactant cetyltrimethylammonium bromide (CTAB), resulting in negative dielectrophoresis of semiconducting species at 10 MHz. A comparative Raman spectroscopy study shows a nearly complete separation of metallic SWNT.

    Original languageBritish English
    Pages (from-to)1541-1545
    Number of pages5
    JournalJournal of Physical Chemistry B
    Issue number4
    StatePublished - 2 Feb 2006


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