Method for functionalizing carbon nanotubes utilizing peroxides
A method for functionalizing the wall of single-wall or multi-wall carbon nanotubes involves the use of acyl peroxides to generate carbon-centered free radicals. The method allows for the chemical attachment of a variety of functional groups to the wall or end cap of carbon nanotubes through covalent carbon bonds without destroying the wall or endcap structure of the nanotube. Carbon-centered radicals generated from acyl peroxides can have terminal functional groups that provide sites for further reaction with other compounds. Organic groups with terminal carboxylic acid functionality can be converted to an acyl chloride and further reacted with an amine to form an amide or with a diamine to form an amide with terminal amine. The reactive functional groups attached to the nanotubes provide improved solvent dispersibility and provide reaction sites for monomers for incorporation in polymer structures. The nanotubes can also be functionalized by generating free radicals from organic sulfoxides.
1. A method for functionalizing a carbon nanotube, comprising:
(a) providing phenyl radicals in the presence of an organic iodide, wherein the phenyl radicals react with the organic iodide to form carbon-centered free radicals; and
(b) reacting the carbon-centered free radicals with a carbon nanotube to form a functionalized carbon nanotube.
2. The method of claim 1 , wherein the functionalized carbon nanotube is a sidewall-functionalized carbon nanotube.
3. The method of claim 1 , wherein (a) the organic iodide comprises an organic group R; (b) the carbon-centered free radicals comprise .R carbon-centered free radicals; and (c) the functionalized carbon nanotube comprises the organic group R bonded to a sidewall of the carbon nanotube.
4. The method of claim 3 , wherein (a) the organic iodide has a form RI; and (b) a carbon atom in the organic group R is bonded to iodine.
5. The method of claim 1 , wherein the carbon nanotube is selected from the group consisting of a single-wall carbon nanotube, a multi-wall carbon nanotube and a combination thereof.
6. The method of claim 1 , wherein the carbon nanotube is a sidewall-fluorinated carbon nanotube.
7. The method of claim 1 , wherein the phenyl radicals are provided by decomposition of benzoyl peroxide.
8. The method of 1 , wherein the organic iodide comprises an organic group selected from the group consisting of an alkyl group, an aryl group, a cyclic group, and combinations thereof.
9. The method of claim 1 , wherein the organic iodide is an alkyl iodide.
10. The method of claim 9 , wherein the alkyl iodide comprises an alkyl group selected from the group consisting of a hydrocarbon alkyl group, an alkyl amide, an alkyl amine, alkyl halide, an alkyl cyanide, a nitro alkyl, an alkyl ether, an alkyl ester, an alkyl ether, an alkyl ketone, an alkyl carboxylic acid, an alkyl carboxylate and combinations thereof.
11. The method of claim 9 , wherein the alkyl iodide comprises an alkyl group comprising heteroatoms selected from the group consisting of nitrogen, oxygen, halogens, and combinations thereof.
12. The method of claim 10 , wherein the alkyl group has a number of carbon atoms in the range of 1 and about 30.
13. The method of claim 11 , wherein the alkyl group has a number of carbon atoms in the range of 1 and about 30.
14. The method of claim 3 , wherein the organic group is a polymeric group.
15. The method of claim 14 , wherein the polymeric group comprises poly(ethylene glycol).
16. The method of claim 14 , wherein the polymeric group is selected from the group consisting of a polyolefin, a polyester, a polyurethane, and combinations thereof.