Method of solubilizing carbon nanotubes in organic solutions

Details Method of solubilizing carbon nanotubes in organic solutions Method of solubilizing carbon nanotubes in organic solutions

2001-02-28

2003-03-11

Lovering, Richard D. (Department: 1712)

Colloid systems and wetting agents; subcombinations thereof; pro

Continuous liquid or supercritical phase: colloid systems;...

Primarily organic continuous liquid phase

C117S921000, C252S182280, C423S460000

Reexamination Certificate

active

06531513

ABSTRACT:

TECHNICAL FIELD
The present invention relates to the dissolution of full length or, unshortened carbon nanotubes in solutions and more particularly, to a method of dissolving carbon metals and semiconductors in organic solutions.
BACKGROUND OF THE INVENTION
All previous work on carbon nanotubes (both single-walled and multi-walled) has been carried out on the usual intractable, insoluble form of this material [Yakobson, B. I.; Smalley, R. E., Fullerene Nanotubes: C1,000.000 and Beyond. American Scientist 1997, 85, 324-337.] This form of the material is not amenable to many of the processing steps that are necessary if the carbon nanotubes (CNTs) are to reach their full potential—particularly in applications that require these materials in the form of polymers, copolymers, composites, ceramics and moldable forms.
While present forms of the CNTs can be heterogeneously dispersed in various media, the interactions between the CNTs and host and between the CNTs themselves are simply physical, and without the formation of chemical bonds. Thus, the advantageous properties of the CNTs are unlikely to be realized on a macroscopic level. What is needed is a method to prepare well-dispersed forms of CNTs perhaps by inducing them to exfoliate from the bundles and dissolve in organic solvents. Although long believed to be impossible, [Ebbesen, T. W., Cones and Tubes: Geometry in the Chemistry of Carbon. Acc. Chem. Res. 1998, 31, 558-566] we now teach such a procedure for the dissolution of all types of CNTs [Chen, J.; Hamon, M. A.; Hu, H.; Chen, Y.; Rao, A. M.; Eklund, P. C.; Haddon, R. C., Solution Properties of Single-Walled Carbon Nanotubes. Science 1998, 282, 95-98; Hamon, M. A.; Chen, J.; Hu, H.; Chen, Y.; Rao, A. M.; Eklund, P. C.; Haddon, R. C., Dissolution of Single-Walled Carbon Nanotubes.
Adv. Mater.
1999, 11, 834-840].
SUMMARY OF THE INVENTION
In accordance with the present invention, a simple method of solubilizing carbon nanotubes is provided. The resulting solutions are anticipated to be useful in the functionalization chemistry of the ends, the exterior walls or convex face and the interior cavity or concave face of carbon nanotubes and processing useful nanotube based polymer, copolymer and composite products and devices for a multitude of applications in various industries including aerospace, battery, fuel cell, healthcare and electromagnetic radiation shielding.
Advantageously, as a result of the present invention, functionalization chemistry of the CNTs can be achieved through the study of both the ionic and covalent solution phase chemistry with concomitant modulation of the single wall nanotube band structure.
Additional advantages and other novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the foregoing and other objects, and in accordance with the purposes of the present invention as described herein, a novel and improved method of dissolving CNT metals and semiconductors in common organic solutions is provided. The method comprises the attaching of an aliphatic carbon chain (which may contain organic residues) to the CNTs so as to render the CNTs soluble in the selected organic solvent.
The attaching step includes directly reacting the carbon nanotubes with an amine having a formula RNH
2
or R
1
R
2
NH wherein R, R
1
and R
2
=(CH
2
)
n
CH
3
where n=9-50. Alternatively, the attaching step includes directly reacting the carbon nanotubes with an alkylaryl amine having a formula RNH
2
Or R
1
R
2
NH wherein R, R
1
and R
2
=(C
6
H
4
)(CH
2
)
n
CH
3
where n=5-50.
In accordance with yet another aspect of the invention, the attaching step includes the steps of (a) mixing the carbon nanotubes with an amine or alkylaryl amine having a formula RNH
2
or R
1
R
2
NH wherein R, R
1
and R
2
=(CH
2
)
n
CH
3
and n=9-50 or R, R
1
and R
2
=(C
6
H
4
)(CH
2
)
n
CH
3
and =5-50; and (b) heating the resulting mixture to a temperature between 50-200° C. More preferably, the heating step is to 60-100° C. for at least 70 hours.
The method may also be described as including the further step of dissolving the resulting carbon nanotubes with attached aliphatic carbon chain in the selected organic solvent. That organic solvent may be an aromatic or chlorinated solvent. Solvents in which the CNTs of the present invention may be solubilized include but are not limited to chlorobenzene, dichlorobenzene, trichlorobenzene, tetrahydrofuran, chloroform, methylene chloride, diethylene glycol dimethyl ether, carbon disulfide, benzene, toluene, tetrachlorocarbon, pyridine, dichloroethane, diethyl ether, xylene, naphthalene, nitrobenzene, ether and mixtures thereof. The solubilities of the carbon nanotubes in these solvents range from about 0.01-5.0 mg/ml.
Advantageously, such a solution not only allows the study of the functionalization chemistry of the open ends, the exterior walls or convex face and the interior cavity or concave face of the nanotubes, but also processing of the nanotubes into useful products for various applications including as intermediates in the preparation of polymer, copolymer and composite materials.
In the following description, there are shown and described various embodiments of this invention, simply by way of illustration of several modes and alternate embodiments best suited to carry out the invention. As it will be realized, the invention is capable of still other and different embodiments, and its several details are capable of modifications in various, obvious aspects all without departing from the invention. Accordingly, the descriptions will be regarded as illustrative in nature and not as restrictive.
DETAILED DESCRIPTION OF THE INVENTION
In the novel method of the present invention, we begin with raw, as prepared, CNT soot (AP-CNTs). The AP-CNTs come in two basic forms: AP-single-walled carbon nanotubes (AP-SWNTs) available from CarboLex, Inc. of Lexington, Ky. and AP-multi-walled carbon nanotubes (AP-MWNTs) available from MER Corporation of 7960 South Kolb Rd, Tucson, Ariz. 85706. The AP-SWNTs are prepared by use of an electric arc technique similar to that described by Journet, C.; Maser, W. K.; Bernier, P.; Loiseau, A.; Lamy de la Chappelle, M.; Lefrant, S.; Deniard, P.; Lee, R. and Fischer, J. E., in Large Scale Production of Single-Walled Carbon Nanotubes by the Electric-Arc Technique. Nature 1997, 388, 756-758. The estimated purity of this material is 40-60% SWNT by volume. Batches of 10 grams may be prepared in a single run and there is considerable scope for further increase in scale. Thus it is possible to contemplate the very large-scale production of this material in the future. The AP-MWNTs are of an estimated purity of less than 10% and the nanotubes are of poor quality with many defective and fused together CNTs. We describe herein routes to soluble CNTs, starting from AP-SWNTs and AP-MWNTs.
In accordance with the present invention, full length or unshortened carbon nanotubes are solubilized. This is accomplished utilizing a simple procedure which advantageously preserves the length of the carbon nanotubes which is one of their primary attractions in many applications.
In a prior art approach described in copending U.S. patent application Ser. No. 09/409,787 filed on Sep. 30, 1999 now U.S. Pat. No. 6,368,569, and entitled “Method of Solubilizing Unshortened Carbon Nanotubes In Organic Solutions”, there are basically two steps in all of the procedures: (1) a pretreatment, or purification step that serves to add carboxylic acid functionalities to the nanotubes and (2) a chemical functionalization step that modifies the carboxylic acid in a way that attaches a long aliphatic carbon chain to th

Affiliated with

Also associated with

Rating

Method of solubilizing carbon nanotubes in organic solutions does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method of solubilizing carbon nanotubes in organic solutions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of solubilizing carbon nanotubes in organic solutions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3065571