Wednesday, July 05, 2006

US Patent 7070754 - Conductive SWNT Rope

Single walled carbon nanotubes (SWNTs) are either conductive or semiconductive depending on the direction of "wrapping" of the nanotubes. The established way to distinguish between different single walled nanotubes is in terms of the vector (n,m) identying the direction of such "wrapping" where n and m are integers. If n=m, or n-m is divisible by 3, than the SWNTs are conductive and otherwise they are semiconductive. Unfortunately, many techniques for fabricating SWNTs produces only a low relative concentration of the conductive nanotubes relative to the semiconductive nanotubes, which is undesirable when attempting to produce conductors such as for electrical wiring. Smalley's group at Rice University discovered/invented manufacturing techniques to overcome this problem ten years ago and, after pending for ten years, a patent for the product is just now issued.

Claim 8 is representative.

8. A single-wall carbon nanotube rope comprising at least 50 single-wall carbon nanotubes of which greater than 10% of the single-wall carbon nanotubes are (n, n) single-wall carbon nanotubes.