Carbon nanotubes (CNTs) have attracted much attention due to their extraordinary mechanical and unique electronic properties. CNTs are being studied for applications in high-strength/low-weight composites and other applications. In order to alter the CNT properties for particular applications, chemical functionalization may be necessary. Development of multifunctional composite materials may require functionalization of a collection of CNTs to allow the tubes to be dispersed more easily in a host matrix.
For many applications of nanotubes in sensors, composites, and other nano devices, chemical functionalization of the nanotubes is necessary. A common approach to functionalize nanotubes is to use a wet chemical procedure or electrochemical procedure. A patented method and system for dry chemical functionalization of a collection of CNTs was developed. This technology is a clean and efficient approach that uses a plasma or glow discharge to functionalize the nanotubes with atomic or molecular chemical species. The method can use direct current, radio frequency (inductive or capacitive), or microwave sources to strike a glow discharge and generate a large number of species needed for functionalization from appropriate source gases.
This technology provides a selective, scalable approach not involving “wet” chemistry, for functionalization of a collection of CNTs with any of a large class of elements and compounds, including hydrogen, alkali metals, selected hydrocarbons, selected organic species, and halogens. A selected precursor gas is irradiated to provide a cold plasma of selected target species in a first chamber. The target species are directed toward an array of CNTs located in a second chamber. A CNT array is functionalized with the target species — at room temperature — to a point of saturation very rapidly, making it an efficient method to functionalize CNTs.