Type

Journal Article

Authors

Jonathan N Coleman
Werner J Blau
Manfred M Kappes
Sergei Lebedkin
Valeria Nicolosi
Shane D Bergin
Silvia Giordani

Subjects

Chemistry

Topics
chemistry pyrrolidinones single walled nanotubes nanotubes solvents particle size amides n methylpyrrolidone

Debundling of single-walled nanotubes by dilution: observation of large populations of individual nanotubes in amide solvent dispersions. (2006)

Abstract Large-scale debundling of single-walled nanotubes has been demonstrated by dilution of nanotube dispersions in the solvent N-methyl-2-pyrrolidone (NMP). At high concentrations some very large (approximately 100 s of micrometers) nanotube aggregates exist that can be removed by mild centrifugation. By measurement of the absorbance before and after centrifugation as a function of concentration the relative aggregate and dispersed nanotube concentrations can be monitored. No aggregates are observed below CNT approximately 0.02 mg/mL, suggesting that this can be considered the nanotube dispersion limit in NMP. After centrifugation, the dispersions are stable against sedimentation and further aggregation for a period of weeks at least. Atomic force microscopy (AFM) 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/semidilute boundary. A population of individual nanotubes is always observed that increases with decreasing concentration until almost 70% of all dispersed objects are individual nanotubes at a concentration of 0.004 mg/mL. The number density of individual nanotubes peaks at a concentration of approximately 10(-2) mg/mL. Both the mass fraction and the partial concentration of individual nanotubes can also be measured and behave in similar fashion. Comparison of the number density and partial concentration also of individual nanotubes reveals that the individual nanotubes have average molar masses of approximately 700,000 g/mol. 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. Finally, the nature of the solvent properties required for dispersion are discussed.
Collections Ireland -> Trinity College Dublin -> PubMed

Full list of authors on original publication

Jonathan N Coleman, Werner J Blau, Manfred M Kappes, Sergei Lebedkin, Valeria Nicolosi, Shane D Bergin, Silvia Giordani

Experts in our system

1
Jonathan Coleman
Trinity College Dublin
Total Publications: 217
 
2
Werner Blau
Trinity College Dublin
Total Publications: 109
 
3
Valeria Nicolosi
Trinity College Dublin
Total Publications: 67
 
4
Shane D Bergin
Trinity College Dublin
Total Publications: 12
 
5
Silvia Giordani
Trinity College Dublin
Total Publications: 37