Isolation and purification of single walled carbon nanotube structures

Abstract

Disclosed are methods for isolating and purifying single wall carbon nanotubes from contaminant matrix material, methods for forming arrays of substantially aligned nanotubes, and products and apparatus comprising a plurality of nanotube structures.

1 . A method for separating carbon nanotubes from contaminants comprising the steps of: introducing nanotube-containing material including contaminants into an aqueous medium containing at least one dispersal agent to create a nanotube solution;
 agitating the solution to coat exposed surfaces of the nanotubes with dispersal agent to form a dispersed nanotube solution; and   removing excess dispersal agent medium from the dispersed nanotube solution.   
     
     
         2 . The method of  claim 1 , wherein the nanotubes include single-walled carbon nanotubes. 
     
     
         3 . The method of  claim 1 , wherein the dispersal agent includes detergents, surfactants, emulsifying agents, chaotropic salts, and ion pairing agents. 
     
     
         4 . The method of  claim 1 , wherein the dispersal agent includes a synthetic detergent. 
     
     
         5 . The method of  claim 1 , wherein the dispersal agent is selected from the group consisting of non-ionic, cationic, and anionic detergents. 
     
     
         6 . The method of  claim 3 , wherein the dispersal agent includes a synthetic detergent in concentrations from about 50% to about 95% of its critical micelle concentration value. 
     
     
         7 . The method of  claim 3 , wherein the dispersal agent includes a synthetic detergent having a hydrophilic-hydrophobic balance value from about 7 to about 13.2. 
     
     
         8 . The method of  claim 3 , wherein the emulsifying agent is present in concentrations from about 5 mg/ml to about 500 mg/ml of aqueous solution. 
     
     
         9 . The method of  claim 1 , wherein the pH of the aqueous medium is substantially neutral at ambient temperature. 
     
     
         10 . The method of  claim 3 , wherein the ion pairing agents are present in concentrations from about 1 mM to about 100 mM in aqueous solution. 
     
     
         11 . The method of  claim 1 , wherein up to about 1 mg of nanotube-containing matrix is added per milliliter of the aqueous dispersal agent medium. 
     
     
         12 . The method of  claim 1 , wherein the filter has a pore size of up to about 0.2 μm. 
     
     
         13 . The method of  claim 1 , wherein the filter has a pore size from about 0.05 μm to about 0.2 μm. 
     
     
         14 . The method of  claim 1 , wherein the method further comprises the steps of: centrifugating the dispersed nanotube solution to sediment contaminants from supernatant containing the nanotubes;
 and filtering the supernatant.   
     
     
         15 . The method of  claim 14 , wherein the filter includes a size exclusion column. 
     
     
         16 . The method of  claim 1 , wherein the method further comprises the step of washing the purified nanotubes with an aqueous wash to remove excess dispersal agent medium. 
     
     
         17 . The method of  claim 1 , wherein the method further comprises the step of depositing the purified nanotubes on a substrate. 
     
     
         18 . The method of  claim 17 , wherein the substrate includes a polymeric support film. 
     
     
         19 . The method of  claim 17 , wherein the substrate includes a surface-coated material. 
     
     
         20 . A method for transforming a carbon nanotube bundle comprised of a plurality of carbon nanotubes into discrete, individual carbon nanotube filaments comprising the steps of introducing the nanotube bundle into an aqueous medium containing an effective amount of a dispersal agent to substantially disperse the nanotube bundle into individual filaments in solution. 
     
     
         21 . The method of  claim 20 , wherein the nanotubes include single-walled carbon nanotubes. 
     
     
         22 . The method of  claim 20 , wherein the dispersal agent is selected from the group consisting of detergents, surfactants, emulsifying agents, chaotropic salts, and ion pairing agents. 
     
     
         23 . The method of  claim 20 , wherein the dispersal agent includes a synthetic detergent. 
     
     
         24 . The method of  claim 20 , wherein the dispersal agent is selected from the group consisting of non-ionic, cationic, and anionic detergents. 
     
     
         25 . The method of  claim 22 , wherein the dispersal agent includes a synthetic detergent in concentrations from about 50% to about 95% of its critical micelle concentration value. 
     
     
         26 . The method of  claim 22 , wherein the dispersal agent includes a synthetic detergent having a hydrophilic-hydrophobic balance value from about 7 to about 13.2. 
     
     
         27 . The method of  claim 22 , wherein the emulsifying agent is present in concentrations from about 5 mg/ml to about 500 mg/ml of aqueous solution. 
     
     
         28 . The method of  claim 22 , wherein the pH of the aqueous medium is substantially neutral at ambient temperature. 
     
     
         29 . The method of  claim 22 , wherein the ion pairing agents are present in concentrations from about 1 mM to about 100 mM in aqueous solution. 
     
     
         40 . A method of solubilizing a carbon nanotube bundle into individual carbon nanotube filaments in an aqueous medium comprising introducing the nanotube bundle into an aqueous medium containing an effective amount of a dispersal agent to substantially disperse the nanotube bundle into individual filaments in solution.