This bonding structure, which is stronger than the sp3 bonds found in diamond, provides the molecules with their unique strength. The chemical bonding of nanotubes are composed entirely of sp2 bonds, similar to those of graphite. The nature of the bonding of a nanotube is described by applied quantum chemistry, specifically, orbital hybridization. There are two main types of nanotubes: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs). They've been able to produce 18-mm-long carbon nanotubes which might be spun into nanofibers. Researchers at the University of Cincinnati (UC) have developed a process to build extremely long aligned carbon nanotube arrays. Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers (approximately 50,000 times smaller than the width of a human hair), while they can be up to several millimeters in length. Whereas buckyballs are spherical in shape, a nanotube is cylindrical, with at least one end typically capped with a hemisphere of the buckyball structure. Nanotubes are members of the fullerene structural family, which also includes buckyballs. Inorganic nanotubes have also been synthesized. They exhibit extraordinary strength and unique electrical properties, and are efficient conductors of heat. Such cylindrical carbon molecules have novel properties that make them potentially useful in many applications in nanotechnology, electronics, optics and other fields of materials science. This results in a nanostructure where the length-to-diameter ratio exceeds 10,000. A single wall carbon nanotube is a one-atom thick sheet of graphite (called graphene) rolled up into a seamless cylinder with diameter of the order of a nanometer. Carbon nanotubes (CNTs) are allotropes of carbon.

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