Single-Wall Carbon Nanotube Film Having High Modulus and Conductivity and Process for Making the Same

Abstract

The invention relates to a film comprising greater than 80 wt % single-wall carbon nanotubes wherein the tensile modulus is at least about 6 GPa at 0.2% strain and the conductivity of the film is at least about 70,000 S/m. The tensile modulus is typically about 8 GPa at 0.2% strain. The method for making the film comprises preparing a solution of single-wall carbon nanotubes in a superacid, such as oleum containing approximately 20 to 30% sulfur trioxide, under a dry, oxygen-free atmosphere. The solution is placed on a surface in a moisture-containing atmosphere, wherein the solution absorbs moisture and acid leaches out. The film is washed to further remove acid, dried, and, optionally, subjected to a heat treatment. Besides free-standing films, coatings of single-wall carbon nanotubes can be made on a variety of surfaces including polymers, glass, metals, and ceramics. The surfaces can be flat planes, fibers or contour shapes.

1 - 15 . (canceled) 
     
     
         16 . A method for making a single-wall carbon nanotube film comprising:
 (a) preparing a mixture comprising single-wall carbon nanotubes and a superacid in a dry, oxygen-free atmosphere; and   (b) forming a film in a moisture-containing atmosphere, wherein the film comprises at least about 80 wt % single-wall carbon nanotubes.   
     
     
         17 . The method of  claim 16 , wherein the superacid is selected from the group consisting of a Brønsted superacid, a Lewis superacid, a Brønsted-Lewis conjugate superacid and mixtures thereof. 
     
     
         18 . The method of  claim 17 , wherein the Brønsted superacid is selected from the group consisting of superacids include perchloric acid, chlorosulfuric acid, fluorosulfuric acid, chlorosulfonic acid, fluorosulfonic acid, perfluoroalkanesulfonic acid, trifluoromethanesulfonic acid, higher perfluoroalkanesulfonic acid, C 2 F 5 SO 3 H, C 4 F 9 SO 3 H, C 5 F 11 SO 3 H, C 6 F 13 SO 3 H, C 8 F 17 SO 3 H, 
       
         
           
           
               
               
           
         
         and α,ω-perfluoroalkanedisulfonic acid. 
       
     
     
         19 . The method of  claim 17 , wherein the Lewis superacid is selected from the group consisting of antimony pentafluoride, arsenic pentafluoride, tantalum pentafluoride and niobium pentafluoride. 
     
     
         20 . The method of  claim 17 , wherein the Brønsted-Lewis conjugate superacid is selected from the group consisting of oleum, polyphosphoric acid-oleum mixtures, tetra(hydrogen sulfato)boric acid-sulfuric acid, fluorosulfuric acid-antimony pentafluoride, fluorosulfuric acid-sulfur trioxide, fluorosulfuric acid-arsenic pentafluoride, HSO 3 F:HF:SbF 5 , HSO 3 F:SbF 5 :SO 3 , a perfluoroalkanesulfonic acid-based system, C n F 2n+1 SO 3 H:SbF 5 , where n=1, 2 or 4, CF 3 SO 3 H:B(SO 3 CF 3 ) 3 , hydrogen-fluoride-antimony pentafluoride, hydrogen fluoride-tantalum pentafluoride, hydrogen fluoride-boron trifluoride, a conjugate Friedel-Crafts acid, HBr:AlBr 3 , and HCl:AlCl 3 . 
     
     
         21 . The method of  claim 16 , wherein the superacid is oleum. 
     
     
         22 . The method of  claim 21 , wherein the oleum contains at most about 30% SO 3 . 
     
     
         23 . The method of  claim 16 , wherein the superacid is trifluoromethanesulfonic acid. 
     
     
         24 . The method of  claim 16 , wherein the single-wall carbon nanotubes are at a concentration range of about 0.01 wt % and about 10 wt % in the acid. 
     
     
         25 . The method of  claim 16 , wherein the single-wall carbon nanotubes are at a concentration range of about 0.05 wt % and about 5 wt % in the acid. 
     
     
         26 . The method of  claim 16  wherein the film comprises at least about 90 wt % single-wall carbon nanotubes. 
     
     
         27 . The method of  claim 16  wherein the film comprises at least about 95 wt % single-wall carbon nanotubes. 
     
     
         28 . The method of  claim 16  wherein the film comprises at least about 99 wt % single-wall carbon nanotubes. 
     
     
         29 . The method of  claim 16  further comprising washing the film to remove the superacid. 
     
     
         30 . The method of  claim 29  wherein the washing is done with a solvent selected from the group consisting of acetone, alcohol, water and a combination thereof. 
     
     
         31 . The method of  claim 16  further comprising drying the film. 
     
     
         32 . The method of  claim 31  wherein the drying is done in an atmosphere selected from the group consisting of a vacuum, nitrogen and inert gas. 
     
     
         33 . The method of  claim 31  wherein the drying is done at a temperature in the range of about room temperature and about 200° C. 
     
     
         34 . The method of  claim 16  further comprising subjecting the film to a heat treatment at a temperature of at least about 200° C. 
     
     
         35 . The method of  claim 16  wherein the film has a tensile modulus of at least about 6 GPa at 0.2% strain. 
     
     
         36 . The method of  claim 35  wherein the film has an electrical conductivity of at least about 7×10 4  S/m. 
     
     
         37 . The method of  claim 16  wherein the film has a tensile modulus of at least about 7 GPa at 0.2% strain. 
     
     
         38 . The method of  claim 37  wherein the film has an electrical conductivity of at least about 7×10 4  S/m. 
     
     
         39 . The method of  claim 16  wherein the film is formed on a substrate. 
     
     
         40 . The method of  claim 16  wherein the film is a coating. 
     
     
         41 . The method of  claim 39  wherein the substrate is selected from the group consisting of glass, polymer, polyethylene, polypropylene, polystyrene, metal, aluminum, stainless steel, and combinations thereof. 
     
     
         42 . The method of  claim 39  wherein the substrate is a fiber. 
     
     
         43 . The method of  claim 42  wherein the fiber comprises a material selected from the group consisting of polyethylene, polypropylene, glass, metal, ceramic and combinations thereof. 
     
     
         44 . The method of  claim 16  wherein the single-wall carbon nanotubes are derivatized with a functional group.