Nanotube Strands Are Centimeters Long

Growing carbon nanotubes as long as 1 mm was once considered a big deal. For many applications, though, much longer tubes are required. Such tubes are now a step closer. A China-U.S. team has synthesized single-walled carbon nanotube (SWNT) strands some 20 cm long [ Science , 294 , 884 (2002)]. These are the longest and strongest assemblies thus far made entirely of carbon nanotubes, according to one scientist familiar with the report. The strands, which look and feel much like human hair, were prepared by mechanical engineering professor Dehai Wu of Tsinghua University, in Beijing, and coworkers by pyrolyzing n -hexane at 1,150 °C in the presence of ferrocene catalyst and thiophene in flowing hydrogen gas. The strand shown here consists of hundreds of nanotubes and is about 10 µm wide. Characterization of the nanotube strands was carried out by materials engineer Pulickel M. Ajayan and coworkers at Rensselaer Polytechnic Institute. They find that the strands ...