Carbon nanotubes have revolutionised various areas of science and technology. Conceptually, carbon nanotubes can be thought of as all sp3 carbons arranged in graphene sheets, which have been rolled up to form a seamless hollow tube. The tubes can be capped at the ends by a fullerene type hemisphere and can have lengths ranging from tens of nanometers to several microns. They can be subdivided into two classes: the single walled carbon nanotubes (SWNT) and multiwalled carbon nanotubes (MWNT). SWNT consists of a single hollow tube with diameters between 0.4 and 2nm while MWNTs are composed of multiple concentric nanotubes ~0.34nm apart where the final MWNT has diameters of 20100nm. The present review describes the types of carbon nanotubes, methods of synthesis, properties & some applications having commercial importance, including biomedical.
