Functionalized carbon nanotubes exhibiting enhanced solubility and methods of making

Abstract

Functionalized carbon nanotubes and dispersions containing functionalized carbon nanotubes are provided. Exemplary functionalized carbon nanotubes include optionally substituted indene-based moieties. Methods of making functionalized carbon nanotubes and dispersions containing functionalized carbon nanotubes are provided. Methods of making conductive carbon nanotube dispersions, including films, are provided. Such methods include heating carbon nanotubes in a solvent in the absence of externally applied energy, to obtain an adduct that includes the solvent moiety bound to the carbon nanotube. Where the solvent includes an indene-based compound, the carbon nanotube thus prepared includes optionally indene-based moieties bound to the carbon nanotubes.

What is claimed is: 
     
         1 . A functionalized carbon nanotube comprising a carbon nanotube and an optionally substituted polycyclic aromatic moiety directly and covalently bound to the wall of the carbon nanotube. 
     
     
         2 . The functionalized carbon nanotube of  claim 1 , wherein the optionally substituted polycyclic aromatic moiety is one or more moieties selected from the group consisting of optionally substituted naphthalene, optionally substituted phenanthrene, optionally substituted pyrene, optionally substituted chrysene, and optionally substituted anthracene. 
     
     
         3 . The functionalized carbon nanotube of  claim 1 , wherein the optionally substituted polycyclic aromatic moiety is directly and covalently bounded to the carbon nanotube via a [4+2] Diels-Alder reaction. 
     
     
         4 . The functionalized carbon nanotube of  claim 1 , wherein the carbon nanotube comprises single-walled carbon nanotube. 
     
     
         5 . A carbon nanotube dispersion, comprising a population of the functionalized carbon nanotubes of  claim 1  and a solvent. 
     
     
         6 . The carbon nanotube dispersion of  claim 5 , wherein the optionally substituted polycyclic aromatic moiety is one or more moieties selected from the group consisting of optionally substituted naphthalene, optionally substituted phenanthrene, optionally substituted pyrene, optionally substituted chrysene, and optionally substituted anthracene. 
     
     
         7 . The carbon nanotube dispersion of  claim 5 , wherein the optionally substituted polycyclic aromatic moiety is directly and covalently bounded to the carbon nanotube via a [4+2] Diels-Alder reaction. 
     
     
         8 . The carbon nanotube dispersion of  claim 5 , wherein the solvent is selected from one or more solvents selected from the group consisting of water, THF, PGMEA, alcohol, hexane, benzene, toluene, xylenes, chlorobenzene, and a mixture thereof. 
     
     
         9 . The carbon nanotube dispersion of  claim 5 , wherein the carbon nanotube comprise single-walled carbon nanotube. 
     
     
         10 . The carbon nanotube dispersion of  claim 5 , wherein the concentration of the carbon nanotubes in the dispersion is greater than 1.5 mg/mL, greater than 1.6 mg/mL, from 0.2 mg/mL to 1 mg/mL, or from 0.2 mg/mL to 0.6 mg/mL. 
     
     
         11 . A method of preparing functionalized carbon nanotube, comprising:
 heating a carbon nanotube and an optionally substituted polycyclic aromatic compound in the absence of externally applied microwave energy to directly and covalently bound the optionally substituted polycyclic aromatic moiety to the wall of the carbon nanotube.   
     
     
         12 . The method of  claim 11 , wherein the optionally substituted polycyclic aromatic moiety is one or more moieties selected from the group consisting of optionally substituted naphthalene, optionally substituted phenanthrene, optionally substituted pyrene, optionally substituted chrysene, and optionally substituted anthracene. 
     
     
         13 . The method of  claim 11 , wherein the optionally substituted polycyclic aromatic moiety is directly and covalently bounded to the carbon nanotube via a [4+2] Diels-Alder reaction. 
     
     
         14 . The method of  claim 11 , wherein the carbon nanotube and the optionally substituted polycyclic aromatic compound are dispersed in a solvent. 
     
     
         15 . The method of  claim 14 , wherein the heating step comprises refluxing the carbon nanotube in the solvent or melting the carbon nanotube in the solvent. 
     
     
         16 . The method of  claim 11 , wherein the optionally substituted polycyclic aromatic compound is used as a solvent. 
     
     
         17 . The method of  claim 11 , wherein the carbon nanotube comprises single-walled carbon nanotube. 
     
     
         18 . The method of  claim 11 , wherein the carbon nanotube is purified prior to reaction. 
     
     
         19 . The method of  claim 11 , wherein the carbon nanotube is greater than 70% pure, or greater than 95% pure. 
     
     
         20 . A functionalized carbon nanotube prepared by the method of  claim 11 . 
     
     
         21 . A method of preparing the carbon nanotube dispersion of  claim 5 , comprising:
 providing a population of the functionalized carbon nanotubes comprising the optionally substituted polycyclic aromatic moiety directly and covalently bound to the wall of the carbon nanotubes; and   dispersing the population of the functionalized carbon nanotubes in a solvent selected from one or more solvents selected from the group consisting of water, THF, PGMEA, alcohol, hexane, benzene, toluene, xylenes, chlorobenzene, and a mixture thereof.   
     
     
         22 . The method of  claim 21 , wherein the carbon nanotube dispersion is prepared by sonication of the functionalized carbon nanotubes in the solvent. 
     
     
         23 . The method of  claim 21 , wherein the method further comprises a step of isolating the functionalized carbon nanotubes from the solvent by extraction or leaching and the extraction. 
     
     
         24 . The method of  claim 23 , wherein the extraction is solid-liquid extraction, liquid-liquid extraction or Soxhlet extraction. 
     
     
         25 . A method of making a conductive carbon nanotube comprising
 reacting a plurality of carbon nanotubes with an optionally substituted polycyclic aromatic compound under conditions sufficient to directly and covalently bound the optionally substituted polycyclic aromatic moiety to the wall of the carbon nanotubes to form a plurality of optionally substituted polycyclic aromatic moiety-carbon nanotube adducts in the absence of externally applied microwave energy;   dispersing the plurality of the adducts in a solvent to form a dispersion;   applying the dispersion to a substrate;   heating the substrate containing the dispersion under conditions sufficient to increase the electrical conductivity of the substrate.   
     
     
         26 . The method of  claim 25 , further comprising a step of removing the solvent prior to the step of heating the substrate. 
     
     
         27 . The method of  claim 25 , wherein the conductive carbon nanotube forms a conductive film. 
     
     
         28 . The method of  claim 25 , wherein the carbon nanotube is single-walled. 
     
     
         29 . A method of separating a population comprising a plurality of semiconducting nanotubes and a plurality of metallic nanotubes, the method comprising
 selectively functionalizing one type of the plurality of semiconducting nanotubes and the plurality of metallic nanotubes by directly and covalently bounding an optionally-substituted polycyclic aromatic moiety to the wall of the type of nanotubes, and separating the functionalized type of nanotubes from the unfunctionalized type of nanotubes based on the presence of the functional groups.   
     
     
         30 . The method of  claim 29  wherein the step of selectively functionalizing comprises refluxing the plurality of semiconducting nanotubes and the plurality of metallic nanotubes in a solvent in the absence of externally applied microwave energy, to obtain an adduct comprising one type of the plurality of semiconducting nanotubes and the plurality of metallic nanotubes selectively bounded with the optionally-substituted polycyclic aromatic moiety. 
     
     
         31 . The method of  claim 29 , wherein the separating step comprises selective extraction or leaching of one type of the plurality of semiconducting nanotubes or the plurality of metallic nanotubes. 
     
     
         32 . The method of  claim 29 , wherein the separating step comprises a solid-liquid extraction or liquid-liquid extraction.