Carbon nanotubes are polymers of pure carbon, and thus possess all of carbon’s versatility, including the ability to form countless combinations and derivatives. In addition, carbon nanotubes are direct beneficiaries of the rich history and vast body of knowledge associated with carbon chemistry.
Consequently, carbon nanotubes can be functionalized in countless ways using a variety of well-understood chemical reactions. In addition, the geometry of a nanotube allows for the formation of novel synthetic structures not possible with other carbon structures.
Carbon nanotubes can be derivatized both covalently, in which other molecules being bonded to the nanotube share an electron with the tube, and non-covalently, in which the other molecule simply adheres to the carbon nanotube’s sidewall, providing a nano-scale coating of the carbon nanotube.
Because the carbon nanotube sidewalls are electrically polarizable, polar molecules can easily adhere to their surfaces. When molecules adhere even non-covalently to the carbon nanotube surface, they often cause subtle changes in the electronic structure of the tubes. Such changes can be easily detected, making carbon nanotubes exquisitely sensitive chemical sensors.
An important aspect of non-covalent derivatization is the association of surfactants with the carbon nanotube surface, enabling them to be suspended in water.