Carbon nanotube is a material, which possess outstanding characteristics and offer remarkable possibilities. This article gives a brief overview of the physico-chemical nature and characterization of single-walled nanotubes (SWNTs). Of the two types of carbon nanotube, the single walled nanotubes are the ones that are more remarkable. Single walled carbon nanotubes have powerful strength and can be highly electrically conducting or semiconducting, also single walled carbon nanotubes may be as thermally conductive as any other material at room temperature, besides single walled carbon nanotubes have a very large surface area per unit mass, with unique optical properties. Those unique properties offer many possibilities to advancements in performance in a wide range of materials and devices.
Since their discovery in 1991 by Ijima, single walled carbon nanotubes raised a great deal of activity in global research community and industry, they have inspired much investment in manufacturing methods, characterization and application development.
Single walled carbon nanotubes are an allotrope of sp2 hybridized carbon, similar to fullerenes. Individual single walled carbon nanotubes are much stronger than steel. The structure of single walled carbon nanotubes have a cylindrical tube like shape comprised of 6-membered carbon rings, as in graphite. The cylindrical tubes of single walled carbon nanotubes may have one or both ends capped with a hemisphere of the buckyball or fullerene structure. Calculated values for tensile strengths of SWNTs are ~ 100 times greater than steel at 1/16th the weight. A single walled carbon nanotubes may be envisioned as a sheet of graphite one atom thick rolled into a tube. The highest measured value of single walled carbon nanotubes is approximately half of the predicted theoretical strength,2 possibly due to defects in the structure.
Some Properties of Single Walled Carbon Nanotubes
Individual single walled carbon nanotubes have current carrying capacities of 109 amp/cm2, higher than those of copper or gold, 3 and semiconducting species exhibit higher electron mobility than silicon. Single walled carbon nanotubes have a distinct optical absorption and fluorescence response, with each chirality demonstrating its own characteristic absorption and fluorescence spectrum. In general, coating formed with single walled carbon nanotubes are highly transparent in the visible and IR regions of the spectrum, making single walled carbon nanotubes an ideal candidate to replace ITO as the transparent conductor of choice for applications such as displays, solar cells and electroluminescent lighting etc. Room temperature thermal conductivity of a single nanotube may be comparable to that of diamond or in-plane graphite, which are generally thought to display the highest measured thermal conductivity of any known material at moderate temperatures.
Single walled carbon nanotubes applications:
Single walled carbon nanotubes are used in reinforced resins and elastomers.
Single walled carbon nanotubes are used in conductive polymer blends and films.
Single walled carbon nanotubes are used in lithium ion batteries and super capacitors.
Single walled carbon nanotubes are used in displays, solar cells and lighting technologies.
Single walled carbon nanotubes are used in
security tags, sensors and memory elements.