Dispersions and solutions of single walled carbon nanotubes
Citation:
Shane D. Bergin, 'Dispersions and solutions of single walled carbon nanotubes', [thesis], Trinity College (Dublin, Ireland). School of Physics, 2008, pp 161Download Item:
Abstract:
Large scale exfoliation of single walled carbon nanotubes (SWNTs) has been
shown in various media. Debundling of SWNTS has been demonstrated by dilution of
nanotube dispersions. On making the initial dispersions, large aggregates (~100s of
microns) are removed by a mild centrifugation step resulting in an isotropic phase
containing bundles of nanotubes. The root mean square bundle diameter, of bundles in this
isotropic phase, has been shown to be concentration dependent. Such debundling has been
demonstrated in the solvents N-methyl-2-pyrrolidone (NMP) and for the narcotic drug y-
Butyrolactone, sometimes referred to as 'liquid ecstasy'. After centrifugation, the
dispersions are stable against sedimentation and further aggregation for a period of weeks
at least. Atomic-force-microscopy studies on deposited films reveal that the bundle
diameter distribution decreases dramatically as concentration is decreased. Detailed data
analysis suggests the presence of an equilibrium bundle number density and that the
dispersions self-arrange themselves to always remain close to the dilute/semi-dilute
boundary. A population of individual nanotubes is always observed which increases with
decreasing concentration until almost seventy percent of all dispersed objects are
individual nanotubes at a concentration of 0.004 mg/ml in the NMP dispersions and for y-
Butyrolactone forty percent of all dispersed objects are individual nanotubes at a
concentration of 6x10'-4 mg/ml. The presence of individual nanotubes in NMP dispersion
was confirmed by photoluminescence spectroscopy. Concentration dependence of the
photoluminescence intensity confirms that the AFM measurements reflect the diameter
distributions in-situ. In addition, Raman spectroscopy confirms the presence of large
quantities of individual nanotubes in the deposited films.
Author: Bergin, Shane D.
Advisor:
Coleman, JonathanPublisher:
Trinity College (Dublin, Ireland). School of PhysicsNote:
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Full text availableKeywords:
Physics, Ph.D., Ph.D. Trinity College DublinMetadata
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