NASA's Langley Research Center researchers have developed a novel method for making carbon nanotubes that are very uniform in size. A template is used to guide the carbon nanotube growth so that all nanotubes are uniform in size. The carbon nanotubes can be used as-grown, uniformly dispersed, and aligned within the template or isolated from the template for use as carbon nanotubes. The solution-based process uses sugar as a carbon source, does not require vacuum, and is thus simple and low-cost in nature.
Mesoporous silica or alumina supports are used as a template for the aligned growth of the carbon nanotubes. Sucrose is deposited in each pore of the template. Upon the application of heat, the single-wall carbon nanotubes grow from the carbon in the sucrose precursor to produce carbon nanotubes of the desired diameter embedded in the silica template. Removing the silica template can isolate the carbon nanotubes.
This technology provides a low-cost method for growing carbon nanotubes of uniform length and diameter. The template and precursor starter materials are inexpensive. Standard furnace ovens can achieve the temperatures required to complete fabrication of the templated carbon nanotubes, and vacuum equipment is not required. The carbon nanotubes are free of metallic catalyst impurities.
Potential applications include electron field emission sources; flat-panel, field-emission displays; use as functional additive for creating high-strength, lightweight, multifunctional composite structures; and advanced electronic devices, interconnects, and packaging materials.