Compositions – Electrically conductive or emissive compositions – Elemental carbon containing
Reexamination Certificate
1999-09-22
2001-12-18
Hendrickson, Stuart L. (Department: 1754)
Compositions
Electrically conductive or emissive compositions
Elemental carbon containing
C423S447100, C423S447200, C423S460000, C423S461000
Reexamination Certificate
active
06331262
ABSTRACT:
TECHNICAL FIELD
The present invention relates to the dissolution of single walled carbon nanotubes in solutions and more particularly, to a method of dissolving naked single walled nanotube 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 single-walled carbon nanotubes (SWNTs) 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 SWNTs can be heterogeneously dispersed in various media, the interactions between the SWNTs and host and between the SWNTs themselves are simply physical, and without the formation of chemical bonds. Thus, the advantageous properties of the SWNTs are unlikely to be realized on a macroscopic level. What is needed is a method to prepare well-dispersed forms of SWNTs 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 SWNTs [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].
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to overcome the above-described limitations and disadvantages of the prior art by providing (1) a method of solubilizing single-walled carbon nanotubes; and (2) solutions of single-walled carbon nanotubes dissolved in an organic solvent. Such solutions are anticipated to be useful in determining the functionalization chemistry of the open ends, the exterior walls or convex face and the interior cavity or concave face of single-walled 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 SWNTs can be determined through the study of both the ionic and covalent solution phase chemistry with concomitant modulation of the single wall nanotube band structure.
Additional objects, 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 single-walled carbon nanotubes and semiconductors in common organic solutions is provided. The method comprises purifying the single-walled carbon nanotubes and terminating ends thereof with carboxylic acid groups. This is followed by shortening the single-walled carbon nanotubes to a length of between substantially 1-1000 nm. Next is the polishing of the single-walled carbon nanotubes. Then follows the converting of the carboxylic acid groups on the ends to acid chloride groups. This is followed by the reacting of the single-walled 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
where n=9-50 or R, R
1
and R
2
=(C
6
H
4
) (CH
2
)
n
CH
3
where n=5-50. The final step is the dissolving of the reacted single-walled carbon nanotubes in the organic solvent. More preferably, RNH
2
is a compound selected from a group including octadecylamine, 4-dodecylaniline, 4-tetradecylaniline and any mixtures thereof.
The terminating step may be further described as the adding of a mineral acid (eg. HCl, HNO
3
, H
2
SO
4
) to an aqueous suspension of purified SWNTs to protonate the ends. The converting and reacting steps may be more specifically described as including (1) reacting of the carboxylic acid groups on the ends of the SWNTs with a reagent selected from a group consisting of SOCl
2
, PCl
5
and any mixtures thereof to induce acid chloride conversion, (2) the mixing of the acid chloride converted SWNTs with the amine or alkylarylamine either without solvent or in an appropriate solvent (eg. toluene, chlorobenzene, dichlorobenzene, dimethylformamide, hexmethylphosphoramide, dimethylsulfoxide and any mixtures thereof) and (3) the heating of the resulting mixture to a temperature between 50°-200° C. and more preferably 90°-100° C. Preferably, the heating is maintained for a least 96 hours during which the reaction is completed.
In accordance with yet another aspect of the present invention, a novel solution is provided comprising single-walled carbon nanotubes dissolved in an organic solvent. That organic solvent is preferably an aromatic or chlorinated solvent. Solvents in which the SWNTs of the present invention may be solubilized include but are not limited to chloroform, dichloromethane, benzene, toluene, chlorobenzene, 1,2-dichlorobenzene, dichlorocarbene, ether, tetrahydrofuran and mixtures thereof. The single-walled carbon nanotubes dissolved in the organic solvent have a length between 1-1000 nm and a diameter between 0.5-100 nm and are connected via amide linkages to branched or unbranched alkyl chains of 5 and more preferably 9 or more carbon atoms in length.
Advantageously, such a solution not only allows the study of the functionalization chemistry of the 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.
Still other objects of the present invention will become apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of this invention, simply by way of illustration of one of the 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 drawings and descriptions will be regarded as illustrative in nature and not as restrictive.
REFERENCES:
patent: 5560898 (1996-10-01), Uchida et al.
patent: 5641466 (1997-06-01), Ebbesen et al.
patent: 5695734 (1997-12-01), Ikazaki et al.
patent: 5698175 (1997-12-01), Hiura et al.
patent: 5716708 (1998-02-01), Lagow
patent: 97-32571 (1997-09-01), None
C. Journet et al., “Large-scale production of single-walled carbon nanotubes by the electric-arc technique,” Nature, (Aug. 21, 1997).
A.G. Rinzler et al., “Large-scale purification of single-wall carbon nanotubes: process, product, and characterization,” Applied Physics A, p. 29-37, (Nov. 22, 1998).
Erik Dujardin et al., “Purification of Single-Shell Nanotubes,” Adv. Mat. Wiley-VCH Verlag GmbH, D-69469 Weinheim, p. 611-613, (Nov. 22, 1998).
Jian Chen et al., “Solution Properites of Single-Walled Carbon Nanotubes,” Reports, (Oct. 2, 1998).
Y. Chen et al., “Chemical attachment of organic functional groups to single-walled carbon nanotube material,” vol. 13 (No. 9), p. 2423-2431, (Sep. 9, 1998).
Thomas W. Ebbesen, “Cones and T
Chen Jian
Haddon Robert C.
Hendrickson Stuart L.
King and Schickli PLLC
University of Kentucky Research Foundation
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