Chemistry of inorganic compounds – Carbon or compound thereof – Elemental carbon
Patent
1997-04-10
2000-07-18
Griffin, Steven P.
Chemistry of inorganic compounds
Carbon or compound thereof
Elemental carbon
423445B, 423460, 423DIG40, 427216, D01F 912, D01F 1112
Patent
active
060903635
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
Carbon nanotubes, or so called `buckytubes`, were first observed by Iijima in 1991.sup.1. A method for macroscopic synthesis of nanotubes giving gram quantity of the material has been subsequently described.sup.2. Typically, the nanotubes consist of multilayers (normally 2-50) of concentric carbon tubes which are capped at both ends. The tubes are built up of sheets of carbon atoms arranged in hexagons and pentagons, with the pentagons concentrated in areas of low radius of curvature such as the tube ends. The tubes contain a hollow core up to 50 nm across typically 100-200 nm in length.
There has been much speculation on the possible physical and chemical properties of filled nanotubes, especially novel magnetic, mechanical, electrical, optical and catalytic properties.sup.3. However, no suitable method for opening and filling the carbon nanotubes with a variety of materials is currently available. There have previously been attempts to insert materials into the tubes by using composite metal-carbon electrodes during arc vaparisation.sup.4-9. These high temperature methods favour the production of metal carbides, the techniques can only be applied to a limited number of materials. In addition, the metal carbides or metal particles are encapsulated by carbon shells, and are thereby isolated from their environment. It has also been reported that if the nanotube is heated in air with lead, the tip of the tube can be opened, followed by the filling of the tube with the molten lead. About it of the tubes were filled in this manner and the presence of internal caps frequently limit the amount of tube filling. Recently, there have been two independent reports of the selective oxidation of nanotubes by carbon dioxide.sup.11 or oxygen.sup.12 in which ends of the nanotubes could be removed at temperatures >600.degree. C. leaving a small portion 2-10%) of opened tubes. Oxidation in this manner also removes the outer layers of hexagonal carbon which form the body of the tubes. In consequence the tubes become thinned. In extremity they can lead to the formation of single layered tubes.sup.11. The filling of open tubes prepared by these gas phase oxidations has proved difficult, probably due to the presence of amorphous carbon blocking the tubes.sup.12. Here we describe a simple wet and highly selective method for the opening of the ends of nanotubes in very high yields, and the filling of these opened tubes with metal compounds.
THE INVENTION
In one aspect the invention provides carbon nanotubes open on at least one end and containing material deposited therein. Generally at least 40%, preferably at least 70% and desirably 100%, of the carbon nanotubes are open on at least one end of the tubes which are open on at least one end, generally at least 10% e.g. at least 40%, preferably at least 70% and desirably 100%, contain material deposited therein. The invention also provides a method of making these open filled carbon nanotubes which method comprises treating capped nanotubes with a liquid comprising an oxidizing agent and a material for deposition in the uncapped nanotubes.
In another aspect, the invention provides carbon nanotubes of which at least 50%, preferably at least 80% and desirably 100%, are open on at least one end. These may be made by treating capped nanotubes with a liquid comprising an oxidising agent.
The material deposited within the open-ended carbon nanotubes may be selected from a wide range, of which the following are examples:
Metals or alloys in elemental form, such as d-block or f-block transition metals; such metals or allows in combined form, e.g. combined with oxygen or carbon; organic compounds, such as may be used for medical purposes; one or more of the elements Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, S, Al, Sc, Y, La, Si, Ge, Sn, N, P, As, Sb, Bi, O, Se, Te, F, Cl, Br, I, He, A, Kr, Xe, which may be useful as heterogeneous catalysts; materials which have ferrimagnetic properties; materials which have molecular sieving properties, and which may be useful as heterogeneou
REFERENCES:
patent: 5346683 (1994-09-01), Green et al.
patent: 5457343 (1995-10-01), Ajayan
patent: 5547748 (1996-08-01), Ruoff
patent: 5549973 (1996-08-01), Majetich
patent: 5560898 (1996-10-01), Uchida
patent: 5641466 (1997-06-01), Ebbesen
patent: 5698175 (1997-12-01), Hiura
Ebbesen, T.W., et al. "Purification of Nanotubes", Nature, vol. 367, p. 519, Feb. 10, 1994.
Tsang, S.C. et al. "A simple chemical method of opening . . . " Nature, vol. 372, No. 6502, Nov. 10, 1994, pp. 159-162.
Lago, R.M. et al. "Filling carbon nanotubes with small palladium . . . " J. Chem. Soc. Chem. Commun. , No. 13, Jul. 7, 1995, pp. 1355-1356.
X.K. Wang et al. "Cabon nanotubes . . . " Applied Physics Letters, vol. 66, No. 18, May 1, 1995, pp. 2430-2432.
K.C. Hwang. "Efficient cleavage of carbon . . . " J. Chem. Soc., chem. Commun., 1995, pp. 173-174.
P.M. Ajayan et al. "Capillary-induced filling of . . . " Nature, vol. 361, No. 6410, Jan. 28, 1993, London, GB, pp. 333-334.
P.M. Ajayan et al. "Opening carbon nanotubes . . . " Nature, vol. 362, No. 6420, Apr. 8, 1993, London, GB, pp. 522-525.
M. Ata et al. "Localized incorporation of Lanthanum . . . " Advanced Materials, vol. 6, No. 7/8, Aug. 1994 Weinheim, DE., pp. 590-592.
S.C. Tsang et al. "Thinning and opening of carbon nanotubes . . . " Nature, vol. 362, No. 6420, Apr. 8, 1993, London, GB, pp. 520-522.
Green Malcolm L. H.
Tsang Shik C.
DiMauro Peter
Griffin Steven P.
Isis Innovation Limited
LandOfFree
Method of opening and filling carbon nanotubes 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 opening and filling carbon nanotubes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of opening and filling carbon nanotubes will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2033544