Carbon: Nanotubes

Abstract A brief introduction to carbon nanotubes with basic structural classification, synthesis, properties, and surface modification is presented. The growth process of carbon nanotubes and the role of metals catalyst in the arc‐discharge, the laser‐vaporization, and the chemical vapor deposition (CVD) techniques are discussed. The synthesis of aligned carbon nanotubes in a preferred orientation from various substrates and the formation of branched carbon nanotubes are unique features of the CVD technique. The method of purification of carbon nanotubes is chosen on the basis of the amount of catalyst impurities and amorphous carbon present in them that are dependent on the techniques used to produce carbon nanotubes. Oxidative purification methods and the introduction of carboxylic acid on the surface of carbon nanotubes have been described. Optical, electrical, and mechanical properties of carbon nantubes have been highlighted. An overview of the surface modification of carbon nanotubes with covalent and noncovalent chemistry to enhance the dispersion and dissolution properties of carbon nantotubes and the problem associated with size, length, and the functional groups distribution affecting the solution properties of carbon nanotubes have been discussed.