Carbon nanotube

Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical
nanostructure. These cylindrical carbon molecules have unusual properties,
which are valuable for nanotechnology, electronics, optics, and other fields of
materials science and technology. Owing to the material s exceptional strength
and stiffness, nanotubes have been constructed with a length-to-diameter ratio of
up to 132,000,000:1,[1] significantly larger than that for any other material.
In addition, owing to their extraordinary thermal conductivity and mechanical
and electrical properties, carbon nanotubes find applications as additives to
various structural materials. For instance, nanotubes form a tiny portion of the
material(s) in some (primarily carbon fiber) baseball bats, golf clubs, car parts,
or damascus steel.[2][3]
Nanotubes are members of the fullerene structural family. Their name is derived
from their long, hollow structure with the walls formed by one-atom-thick sheets
of carbon, called graphene. These sheets are rolled at specific and discrete
("chiral") angles, and the combination of the rolling angle and radius decides the
nanotube properties, for example, whether the individual nanotube shell is a metal or semiconductor. Nanotubes are categorized as
single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs). Individual nanotubes naturally align themselves into
"ropes" held together by van der Waals forces, more specifically, pi-stacking.
Applied quantum chemistry, specifically orbital hybridization, best describes the chemical bonding in nanotubes. The chemical
bonding of nanotubes involves entirely sp2-hybrid carbon atoms. These bonds, which are similar to those of graphite and stronger
than those found in alkanes and diamond (which employ sp3-hybrid carbon atoms), provide nanotubes their unique strength.