Methods of dispersing carbon nanotubes

Patent metadata

Field	Value
Publication number	US-10144638-B2
Application number	US-28230407-A
Country	US
Kind code	B2
Filing date	Mar 9, 2007
Priority date	Mar 9, 2006
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

A method is described for preparing carbon nanotube dispersions in organic solvents such as chloroform and methyl ethyl ketone. Structures resulting from organic dispersions are also disclosed. The dispersing agents used in this method comprise long chain hydrocarbons, halogen-substituted hydrocarbons, fluorocarbons, or a mixture of hydrocarbons, halogen-substituted hydrocarbons, and fluorocarbons; wherein the hydrocarbons, halogen-substituted hydrocarbons and fluorocarbons have from 6 to 40 carbons in a chain, at least one alkene or alkyne moiety, and at least one pendant carboxylic acid, phosphonic acid, and/or sulfonic acid group or an ester of these acids.

First claim

We claim:

1. A process for dispersing carbon nanotubes in an organic solvent, comprising:
mixing carbon nanotubes with a dispersing agent; wherein the dispersing agent comprises long chain hydrocarbons, halogen-substituted hydrocarbons, fluorocarbons, or a mixture of hydrocarbons, halogen-substituted hydrocarbons, and fluorocarbons; and wherein the hydrocarbons, halogen-substituted hydrocarbons and fluorocarbons have from 6 to 40 carbons in a chain, at least one alkene or alkyne moiety, and at least one pendant carboxylic acid, phosphonic acid, and/or sulfonic acid group or an ester of these acids.

2. The process of claim 1 wherein the mixture of carbon nanotubes and dispersing agent is sonicated.

3. The process of claim 1 wherein excess dispersing agent is removed, and further wherein the carbon nanotubes resulting from this treatment are subsequently dispersed in a volatile organic solvent.

4. The process of claim 1 wherein the carbon nanotubes comprise multi-wall carbon nanotubes.

5. The process of claim 1 wherein a paste comprising carbon nanotubes and dispersing agent is obtained, and this paste is filtered to remove excess solvent and dispersing agent.

6. The process of claim 1 wherein, after treatment with the dispersing agent, the treated nanotubes are washed with a solvent to remove excess dispersing agent.

7. The process of claim 1 wherein the dispersing agent comprises hydrocarbons and/or fluorocarbons that have from 8 to 22 carbons in a chain.

8. The process of claim 1 wherein the dispersing agent comprises ethyl-2-octynoate, methyl oleate, oleic acid, or methyl-5-hexyonate.

9. The process of claim 1 wherein the dispersing agent comprises a sulfonyl head and a oligourethane or oligo-siloxane tail.

10. The process of claim 1 wherein the dispersing agent comprises a dendrimer.

11. The process of claim 1 wherein the process yields a dispersion of carbon nanotubes in organic solvent of at least 8 mg/L.

12. The process of claim 1 wherein the carbon nanotubes are dispersed in a volatile organic solvent selected from the group consisting of methyl ethyl ketone, butyl acetate, propyl acetate, and combinations thereof.

13. The process of claim 1 wherein the carbon nanotubes that result from the treatment exhibit a G/D ratio in the Raman spectrum of at least 14 and an onset of decomposition determined by thermogravimetric analysis in air of at least 380° C.

14. The process of claim 1 wherein the dispersing agent comprises a sulfonic acid, sulfonic ester, phosphonic acid, or phosphonic ester group.

15. The process of claim 1 wherein the dispersing agent does not lower the conductivity of the final product.

16. The process of claim 1 wherein the carbon nanotubes are first treated with neat dispersing agent and sonication, then washed to remove excess dispersing agent, and finally dispersed in organic solvent.

17. The process of claim 1 wherein the dispersing agent comprises:
a long straight chain or branched carboxylic acid or ester having the structure:

where R 1 is H or straight chain or branched aliphatic, R 2 is a group containing one or more non-conjugated alkenes or alkynes or their mixtures, and R 3 is straight chain or branched aliphatic.

18. The process of claim 1 wherein the dispersing agent comprises:
a long straight chain or branched carboxylic acid or ester containing at least one or more non-conjugated alkenes or alkynes and at least 6 carbon atoms with a structure such as:

where R 1 is H or straight chain or branched aliphatic, R 2 is a straight chain or branched alkyl group, and R3 is a group containing one or more non-conjugated alkenes or alkynes or their mixtures.

19. The process of claim 1 wherein the dispersing agent comprises:

20. A carbon nanotube dispersion made by the process of claim 1 .

21. A carbon nanotube network made by depositing the dispersion of claim 1 onto a hydrophobic polymeric substrate.

22. A carbon nanotube / polymer composite made from the dispersion of claim 1 .

23. A structure comprising:
a carbon nanotube film deposited from organic solvent comprising the dispersing agent of claim 1 wherein the carbon nanotube film exhibits:
a transmittance of about 80% at 550 nm and a sheet resistance of 20 to about 100,000ohms/square; or
a bulk conductivity in the range 1 to 1000 S/cm.

24. The structure of claim 23 comprising the dispersing agent of claim 1 .

Assignees

• Heintz Amy M
• Cafmeyer Jeffrey
• Elhard Joel D
• Vijayendran Bhima R
• Battelle Memorial Institute

Inventors

• Heintz Amy M
• Cafmeyer Jeffrey
• Elhard Joel D
• Vijayendran Bhima R

Classifications

• B82Y10/00 Primary

  Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic · CPC title

• H01L51/0048

  Electricity · mapped topic

• H01L51/0007

  Electricity · mapped topic

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title

• C01B2202/06

  Multi-walled nanotubes · CPC title