Sticky Tape Sorts Nanotubes

Taking a cue from Nobel Prize-winning physicists who prepared graphene with adhesive tape, a research team has developed sticky polymer films to separate metallic and semiconducting single-walled carbon nanotubes (Angew. Chem. Int. Ed., DOI: 10.1002/anie.201101700). Fabrication of these nanotubes typically yields a mixture of the two types. In the past, researchers separated them by selectively destroying one nanotube type or by using solution-based methods such as dielectrophoresis. Researchers led by Jin Zhang of China’s Peking University have now demonstrated a less labor-intensive separation of the nanotubes using polydimethylsiloxane thin films modified with either amine or phenyl groups. When pressed onto an array of nanotubes and peeled away, amine-terminated tapes bind to and remove semiconducting nanotubes. Likewise, phenyl-terminated tapes remove metallic nanotubes. Stanford University’s Zhenan Bao, who has sorted nanotubes with chemically functionalized surfaces, says methods like this one that harness the power of molecule-nanotube interactions “will be highly desirable for low-cost electronics.”