Single-wall carbon nanotubes (SWNTs) are fullerenes of closed-cage carbon molecules typically arranged in hexagons and pentagons. Commonly known as “buckytubes,” these cylindrical carbon structures have extraordinary properties, including high electrical and thermal conductivity, as well as high strength and stiffness. With intrinsic strength estimated to be on the order of 100 times that of steel, SWNTs are a possible strengthening reinforcement in composite materials. The intrinsic electronic properties of SWNTs also make them electrical conductors and useful in applications involving field mission devices such as flat-panel displays, and in polymers used for radio frequency interference and electromagnetic shielding that require electrical conductance properties.

The present invention is a composition of matter that provides a new, discrete aggregate comprising highly aligned SWNTs. The aggregates are called “carbon alewives” for their resemblance to the Atlantic fish bearing that name. The SWNT alewife aggregate is distinct. The shape is acicular, or needle-like, with a thicker middle that tapers toward the ends. Alewives are substantially free of tangles of long ropes, and can be easily dispersed and incorporated into other materials such as polymers, metals, ceramics, metal oxides, and liquids. This invention also includes composites comprising carbon alewives, wherein the SWNTs are substantially aligned, and impart properties such as reinforcement, enhanced tensile strength, and/or electrical and thermal conductivity to the composite.

The process for dispersing single-wall carbon nanotubes involves mixing the SWNTs with 100% sulfuric acid or a special superacid, and heating and stirring under an inert, anhydrous, oxygen-free environment. The SWNT/acid mixture is wet spun into a coagulant to form the SWNT fibers. The fibers are recovered, washed, and dried. The size of the fibers is dependent on the initial SWNT concentration in the acid, and is monodispersed for each concentration. The SWNTs are highly aligned in the fibers, as determined by Raman spectroscopy analysis.

This work was done by Richard Smalley, Rajesh Saini, Ramesh Sivarajan, Robert Hauge, Virginia Davis, Matteo Pasquali, and Lars Ericson of Rice University for Johnson Space Center. For further information, contact the JSC Technology Transfer Office at (281) 483-3809.

In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:

Rice University
P.O. BOX 1892
Houston, TX 77251-1892

Refer to MSC-25255-1.


NASA Tech Briefs Magazine

This article first appeared in the June, 2015 issue of NASA Tech Briefs Magazine.

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