Single-Walled Carbon Nanotube (C(n)) — Properties, Uses & Safety

Overview

Single-walled carbon nanotubes (SWCNTs) are cylindrical nanostructures made entirely of carbon atoms, with the formula written as C(n) since they are extended structures with no fixed molecular weight. Imagine rolling a single sheet of graphene into a seamless tube with a diameter of about 1 to 2 nanometers — that is essentially what a single-walled carbon nanotube is. The carbon atoms are sp2 hybridized and arranged in a hexagonal lattice, similar to graphene, giving nanotubes extraordinary properties. SWCNTs are approximately 100 times stronger than steel at one-sixth the weight, making them among the strongest materials known. They exhibit remarkable electrical properties that depend on their chirality — the angle at which the graphene sheet is rolled. Some nanotubes are metallic conductors, while others are semiconductors, a property determined entirely by their geometric structure. SWCNTs also have exceptional thermal conductivity, exceeding that of diamond along their axis. At standard conditions, carbon nanotubes appear as a black powder or fibers. The GHS hazard code H373 (may cause organ damage through prolonged exposure) reflects concerns about inhalation of nanoparticle fibers, similar to asbestos-like health risks that are still being studied. Applications for carbon nanotubes include reinforcing composite materials, creating nanoscale electronic components, developing advanced battery electrodes, building chemical sensors, and potentially constructing a space elevator cable. For chemistry students, carbon nanotubes are a compelling example of how atomic-scale structure determines macroscopic properties. They extend the carbon allotropy series (diamond, graphite, graphene, fullerenes, nanotubes) and demonstrate that the same element can exhibit metallic or semiconducting behavior depending solely on geometry. Nanotubes connect to lessons on hybridization, bonding, band theory, and the emerging field of nanotechnology that is reshaping materials science and engineering.

IUPAC Name

carbon nanotube

CAS Number

308068-56-6

PubChem CID

0

Molecular Formula

C(n)

Molar Mass

0 g/mol

State at STP

solid

Appearance

Black powder or fibers