CMU Revamps Growth of Carbon Nanotubes
Source Newsroom: Central Michigan University
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Journal of the American Chemical Society first appearing online June 23 (online, 23-Jun-2004)
Newswise — Central Michigan University researchers have made a precedent-setting nanotechnology discovery that can lead to many industrial applications and open the door to more studies.
In the first reported instance, Bradley Fahlman, a faculty member in CMU's chemistry department and lead researcher on the project, has successfully grown multiwalled carbon nanotubes on a dendrimer-based catalyst at 175 degrees Celsius, the lowest-reported temperature to date.
"This is the first instance of growing nanotubes from a dendrimer at temperatures low enough to retain individual links between nanotubes and dendrimers," said Fahlman. "Our low-temperature procedure represents a new type of 'tip-growth' mechanism that is very different than those proposed for high-temperature methods. Our relatively mild conditions will allow for more detailed investigations related to the mechanism(s) for nanotube growth, from its inception."
Carbon nanotubes can be used in applications such as nanoelectronics, hydrogen storage, field emission display panels, and as reinforcements for plastics, rubber and other polymers.
Fahlman grew small-diameter nanotubes at 175 degrees Celsius. Traditional methods involve temperatures between 600 and 1000 degrees. Only less well-defined and larger-diameter nanotubes have been grown at less than 300 degrees until now, said Fahlman.
The results of Fahlman's study, "Low-Temperature Growth of Carbon Nanotubes from the Catalytic Decomposition of Carbon Tetracholoride," are published as an ASAP article, first appearing online June 23 at the Journal of the American Chemical Society on the Web: http://pubs.acs.org/journals/jacsat/index.html.
The discovery also opens the field for more studies. Dendrimers are a novel class of three-dimensional nanoscale, core-shell structures that can be precisely synthesized for a wide range of applications. Dendritic polymers are recognized as the fourth major class of polymers.
Fahlman was assisted on the project by postdoctoral researcher Jason Vohs, CMU seniors Jonathan Brege of Rogers City and Allan Brown of Bay City, CMU graduate student Jeffery Raymond of Lake, and Geoffrey Williams, supervisor of CMU's electron microscopy facility. CMU graduate student Martin Bennett of Charlevoix performed the Raman spectroscopic analysis.
Fahlman said CMU professors Bob Howell and Dillip Mohanty and Donald Tomalia, president and chief technology officer at Dendritic NanoTechnologies Inc. at CMU, provided valuable and generous support. Tomalia is a world-renowned scientist who discovered dendrimers.
Cottrell College Science Award (CC6045) from Research Corp. and CMU's College of Science and Technology and department of chemistry provided financial support for the project. Ewa Danielewicz at the Michigan State University Center for Advanced Microscopy provided field-emission scanning electron microscopic images.
"The nanotechnology field is moving like the wind," said James Hageman, CMU vice provost for research. "CMU has filed a patent on the Fahlman process, as we believe the potential applications for carbon nanotubes are nearly endless. The materials may exhibit semiconductor or metallic conductivity depending on their morphology and are lighter and stronger than copper. They can change and enhance the properties of plastics. We believe Fahlman's process will make carbon nanotubes a practical and marketable product."