As you probably know, carbon nanotubes have very interesting mechanical, electrical and optical properties. But they are 'small.' Now, researchers at the University of Cincinnati (UC) have developed a process to build extremely long aligned carbon nanotube arrays. They've been able to produce 18-mm-long carbon nanotubes which might be spun into nanofibers. Such electrically conductive fibers could one day replace copper wires. The researchers say their nanofibers could be used for applications such as nanomedicine, aerospace and electronics.
 On the left is a CNT array image of UC|21, representing UC's strategic mission statement. (Credit: UC). This research work has been led by UC researchers Vesselin Shanov and Mark Schulz, co-directors of the UC Smart Structures Bio Nanotechnology Laboratory (UCSSBNL).
After developing their new method for growing long nanotube arrays, the team used the EasyTube™ 3000 System of First Nano, a division of CVD Equipment Corporation, to produce extremely long CNT arrays (18 mm) and other engineering marvels.
Now, here are some technical details about how the researchers built their long CNTs.
The UC substrate for growing CNT arrays is a multilayered structure with a sophisticated design in which a metal based catalyst alloy is formed on top of an oxidized silicon wafer. Its manufacturing requires a “clean room” environment and thin-film deposition techniques that can be scaled up to produce commercial quantities. CNT synthesis is carried out in a hydrogen/hydrocarbon/water/argon environment at 750 degrees Celsius. The achievement of growing centimeter-long nanotube arrays provides hope that continuous growth of CNTs in the meter length range is possible.
Five months ago, the longest CNTs created at UC were 7 millimeters long (please read this former news release, November 29, 2006). And now, the team is thinking about meter-long nanofibers. There will be such a range between the length and the width that I'm wondering if these future nanofibers will keep to be 'solid.'
Sources: University of Cincinnati news release, April 25, 2007; and various websites
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