| Role of surfactants in carbon nanotubes density gradient separation. | |
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MedLine Citation:
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PMID: 20055484 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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Several strategies aimed at sorting single-walled carbon nanotubes (SWNT) by diameter and/or electronic structure have been developed in recent years. A nondestructive sorting method was recently proposed in which nanotube bundles are dispersed in water-surfactant solutions and submitted to ultracentrifugation in a density gradient. By this method, SWNTs of different diameters are distributed according to their densities along the centrifuge tube. A mixture of two anionic amphiphiles, namely sodium dodecylsulfate (SDS) and sodium cholate (SC), presented the best performance in discriminating nanotubes by diameter. We present molecular dynamics studies of the water-surfactant-SWNT system. The simulations revealed one aspect of the discriminating power of surfactants: they can actually be attracted toward the interior of the nanotube cage. The binding energies of SDS and SC on the outer nanotube surface are very similar and depend weakly on diameter. The binding inside the tubes, on the contrary, is strongly diameter dependent: SDS fits best inside tubes with diameters ranging from 8 to 9 A, while SC is best accommodated in larger tubes, with diameters in the range 10.5-12 A. The dynamics at room temperature showed that, as the amphiphile moves to the hollow cage, water molecules are dragged together, thereby promoting the nanotube filling. The resulting densities of filled SWNT are in agreement with measured densities. |
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Authors:
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Elton J F Carvalho; Maria Cristina dos Santos |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: ACS nano Volume: 4 ISSN: 1936-086X ISO Abbreviation: ACS Nano Publication Date: 2010 Feb |
Date Detail:
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Created Date: 2010-02-23 Completed Date: 2010-05-07 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101313589 Medline TA: ACS Nano Country: United States |
Other Details:
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Languages: eng Pagination: 765-70 Citation Subset: - |
Affiliation:
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Departamento de Fisica dos Materiais e Mecanica, Universidade de Sao Paulo, 05315-970 Sao Paulo SP, Brazil. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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