Drexel Nanotechnology Research Paves the Way to Ever Smaller Electronic Devices
The alternating pattern of PE-b-PEO formed on SWNTs with a 12 nm period imaged using transmission electron microscopy. The dark and bright stripes represent the PEO and PE domains, respectively.Image Source: Drexel University
Professor Christopher Li in Drexel University’s Department of Materials Science and Engineering and colleagues are one step closer to making personal electronic devices even smaller. Their research demonstrates that it is possible to manipulate a carbon nanotube, the building block of nanotechnology applications, for the future miniaturization of electronic devices, including computers, cell phones, and PDAs. Carbon nanotubes, or CNTs -- the diameter of only a few millionths of a human hair -- are favored in nanotechnology research and applications for their unusual properties. To be able to use CNTs to create ever smaller electronic devices, a nanotube would have to be furnished with multiple transistors. To achieve this goal, one has to be able to fabricate uniform, large-scale, controllable patterns on CNTs at a few tenths of a nanometer scale, a difficult task which to date has not been successfully addressed. Drexel researchers, led by Professor Li, have now demonstrated that it is possible to create periodic, alternating patterns on carbon nanotubes with a period of 12 nanometers by decorating carbon nanotubes with judiciously selected crystalline block copolymers (in this case polyethylene-block-poly(ethylene oxide)). Block copolymers are comprised of two chemically different polymer chains that are covalently linked together at one end. The trick is to select two blocks of the copolymer so that one has a strong tendency to crystallize on the carbon nanotube surface and the other block can then be brought to the vicinity of the carbon nanotube. The period of the pattern can be easily controlled to be ~10-100 nanometers by simply varying the molecular weight of the block copolymers.
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