HOW long is a carbon nanotube? Until recently, the answer was no more than a few micrometres. But the creation of the world鈥檚 longest nanotube suggests there is no fundamental length limit.
Nanotubes will grow only with the help of a catalyst such as a particle of iron, which encourages carbon to crystallise into tubes. But the tubes tend to bump into surfaces, preventing them from growing beyond a few micrometres. Now Yuntian Zhu and colleagues at Los Alamos National Laboratory in New Mexico have overcome this problem (Nature Materials, DOI: 10.1038/nmat1216). When they suspended an iron particle in a hot chamber containing alcohol vapour as the source of carbon, the nanotube trailed behind the particle. 鈥淚t was like a kite, with the growing nanotube as the string,鈥� Zhu says.
Suspending the tube as it grew meant it reached a record length of 4 centimetres, and longer tubes should be possible, says Zhu.
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