Method for functionalizating carbon naontubes 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 carbon nanotubes, said method comprising:
(a) providing methyl radicals in the presence of an organic iodide, wherein the methyl radicals react with the organic iodide to form carbon-centered free radicals; and
(b) reacting the carbon-centered free radicals with carbon nanotubes to form functionalized carbon nanotubes, wherein reacting comprises forming carbon-carbon bonds between the carbon nanotubes and the carbon-centered free radical.
2. The method of claim 1 , wherein the functionalized carbon nanotubes are sidewall-functionalized carbon nanotubes.
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 nanotubes comprise the organic group R bonded to a sidewall of the carbon nanotubes.
4. The method of claim 3 , wherein the organic group comprises a polymeric group.
5. The method of claim 4 , wherein the polymeric group comprises poly(ethylene glycol).
6. The method of claim 4 , wherein the polymeric group is selected from the group consisting of a polyolefin, a polyester, a polyurethane, and combinations thereof.
7. The method of claim 1 , wherein the carbon nanotubes are selected from the group consisting of single-wall carbon nanotubes, multi-wall carbon nanotubes, sidewall-fluorinated carbon nanotubes and combinations thereof.
8. The method of claim 1 , wherein the methyl radicals are formed by a reaction of dimethyl sulfoxide and hydroxyl radicals.
9. The method of claim 8 , wherein the hydroxyl radicals are generated using Fenton's reagent.
10. The method of claim 8 , wherein the hydroxyl radicals are generated from hydrogen peroxide.
11. The method of claim 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.
12. The method of claim 1 , wherein the organic iodide is an alkyl iodide.
13. The method of claim 12 , 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.
14. The method of claim 13 , wherein the alkyl group has a number of carbons in a range of 1 and about 30.
15. The method of claim 12 , wherein the alkyl iodide comprises an alkyl group comprising heteroatoms selected from the group consisting of nitrogen, oxygen, halogens, and combinations thereof.
16. The method of claim 15 , wherein the alkyl group has a number of carbons in a range of 1 and about 30.