Single Wall Carbon Nanotubes (SWCNTs) exhibit extraordinary properties due to their unusual structure. They consist of a hollow cylinder of carbon, typically ~ 1nm in diameter, with very high aspect ratio (typically > 1,000). This structure can have remarkable optical and electronic properties, tremendous strength and flexibility, and high thermal and chemical stability. As a result, SWCNTs are expected to revolutionize several industries, including displays, electronics, health care and composites.
It is well known that SWCNT properties strongly depend on their diameter and orientation of the carbon hexagons (helicity) that form their walls. The various combinations of diameter and helicity are uniquely specified by the chiral vector identified with the integers (n,m). Unfortunately, most synthesis methods result in a wide distribution of chirality. If well-defined SWCNT samples are desired, one can attempt to separate them on the basis of different affinities to functional groups or adsorbates. However, a more commercially viable approach is the selective growth of SWCNTs with well-controlled structures. This enhanced quality control would greatly facilitate the development of SWCNT-based transistors, optoelectronic devices, photovoltaics, sensors, cancer treatment drugs, nanobiodetectors, etc.
In addition, bulk applications such as composites will require thousands of kilotonnes per year of SWCNTs at much lower cost ($1/g or less). Most synthesis methods are either not considered scalable for such outputs or are not capable of meeting cost and/or quality requirements when produced in such high volumes.
The inability of SWCNT suppliers to meet customer needs for quality, scalability and cost has prevented SWCNT-based products from becoming a commercial reality. However, recent advances in selective synthesis technology and significant investment in large-scale reactors will soon change this situation dramatically.