Nano Chemistry

A carbon nanotube (CNT) is a tube made of carbon with diameters typically measured in nanometres. A scanning tunneling microscopy image of a single-walled carbon nanotube Rotating single-walled zigzag carbon nanotube Single-wall carbon nanotubes (SWCNTs) Single-wall carbon nanotubes are one of the allotropes of carbon, intermediate between fullerene cages and flat graphene, with diameters in the range of a nanometre. Although not made this way, single-wall carbon nanotubes can be idealized as cutouts from a two-dimensional hexagonal lattice of carbon atoms rolled up along one of the Bravais lattice vectors of the hexagonal lattice to form a hollow cylinder. In this construction, periodic boundary conditions are imposed over the length of this roll-up vector to yield a helical lattice of seamlessly bonded carbon atoms on the cylinder surface.[1] Multi-wall carbon nanotubes (MWCNTs) consisting of nested single-wall carbon nanotubes[1] weakly bound together by van der Waals interactions in a tree ring-like structure. If not identical, these tubes are very similar to Oberlin, Endo, and Koyama's long straight and parallel carbon layers cylindrically arranged around a hollow tube.[2] Multi-wall carbon nanotubes are also sometimes used to refer to double- and triple-wall carbon nanotubes. Carbon nanotubes can also refer to tubes with an undetermined carbon-wall structure and diameters less than 100 nanometres. Such tubes were discovered in 1952 by Radushkevich and Lukyanovich.[3][4] The length of a carbon nanotube produced by common production methods is often not reported, but is typically much larger than its diameter. Thus, for many purposes, end effects are neglected and the length of carbon nanotubes is assumed infinite. Carbon nanotubes can exhibit remarkable electrical conductivity,[5][6] while others are semiconductors.[7][8] They also have exceptional tensile strength[9] and thermal conductivity[10][11][12] because of their nanostructure and strength of the bonds between carbon atoms. In addition, they can be chemically modified.[13] These properties are expected to be valuable in many areas of technology, such as electronics, optics, composite materials (replacing or complementing carbon fibers), nanotechnology, and other applications of materials science.