Carbon nanotube pastes and methods of use

Abstract

Discernable pastes comprising single-walled carbon nanotubes (SWNT) in water or in an organic solvent are prepared. The method of preparing the Discernable pastes comprises in general the following steps: a) removal of the catalyst used during the synthesis of SWNT; b) while the SWNT are still wet, addition of the appropriate amount of solvent, in a solvent/SWNT ratio which preferably varies between 30:1 and 100:1, depending on the desired viscosity of the paste; and c) high-energy horn sonication with a dismembrator probe. The resulting pastes are suitable for easy redispersion in solvents and surfactants and incorporation in various matrices such as polymers. They are also suitable to be impregnated with metal precursors such as noble metal compounds for example, Pt. Appropriate drying and thermal treatments of the impregnated material produce metal-SWNT composites in which small metal clusters can be uniformly dispersed over the nanotube surface. These metal-SWNT composites may find applications as catalysts as well as electrodes for fuel cells, batteries, and capacitors.

1 . A carbon nanotube resuspension, comprising:
 a carbon nanotube dispersion comprising single-walled carbon nanotubes dispersed in a solvent and having a paste-like consistency; and   a surfactant solution, and wherein the carbon nanotube dispersion in the surfactant solution has been sonicated with a horn sonicator at 500-750 W such that after 5 minutes of sonication the carbon nanotube resuspension of the single-walled carbon nanotubes in the surfactant solution comprises at least 50% of a maximum attainable resuspension of the single-walled carbon nanotubes in the surfactant solution as measured by optical absorption at a wavelength of 800-900 nm.   
     
     
         2 . The carbon nanotube resuspension of  claim 1  wherein the single-walled carbon nanotubes are non-functionalized. 
     
     
         3 . The carbon nanotube resuspension of  claim 1  wherein the single-walled carbon nanotubes comprise at least 2% by weight of the carbon nanotube dispersion. 
     
     
         4 . The carbon nanotube resuspension of  claim 1  wherein the solvent of the carbon nanotube dispersion is water. 
     
     
         5 . The carbon nanotube resuspension of  claim 1  wherein the solvent of the carbon nanotube dispersion is an organic solvent. 
     
     
         6 . The carbon nanotube resuspension of  claim 1  wherein the carbon nanotube dispersion has a viscosity of at least. 111 Pa.sec at a shear rate of ≦3657 s −1 . 
     
     
         7 . A method of providing a single-walled carbon nanotube resuspension comprising:
 providing a carbon nanotube dispersion comprising single-walled carbon nanotubes dispersed in a solvent and having a paste-like consistency;   combining the carbon nanotube dispersion with a surfactant solution to make a nanotube-surfactant mixture; and   sonicating the nanotube-surfactant mixture with a horn sonication at 500-750 W wherein after 5 minutes of sonication a resuspension of the single-walled carbon nanotubes in the nanotube-surfactant mixture has at least 50% of a maximum attainable resuspension of the single-walled carbon nanotubes in the nanotube-surfactant mixture, wherein the resuspension of the single-walled carbon nanotubes is measured by optical absorption at a wavelength of 800-900 nm.   
     
     
         8 . The method of  claim 7  wherein the single-walled carbon nanotubes are non-functionalized. 
     
     
         9 . The method of  claim 7  wherein the single-walled carbon nanotubes comprise at least 2% by weight of the carbon nanotube dispersion. 
     
     
         10 . The method of  claim 7  wherein the solvent of the carbon nanotube dispersion is water. 
     
     
         11 . The method of  claim 7  wherein the solvent of the carbon nanotube dispersion is an organic solvent. 
     
     
         12 . The method of  claim 7  wherein the carbon nanotube dispersion has a viscosity of at least. 111 Pa.sec at a shear rate of ≦3657 s −1 .