Carbon nanotubes (CNT) possess extraordinary electrical, mechanical, optical, thermal, and chemical properties and find wide applications ranging from improving consumer electronics, to medicine delivery to cells, to strengthening airplane components.
Forms of CNT
Carbon nanotubes come in many different forms and purities. They range from flexible, thin, few-walled or single-walled nanotubes, typically short (less than 5 micron in length), very specialized, high molecular weight fullerene and with single or very few walls to rigid, long, thick, multi-walled nanotubes.
Their forms are - Single wall (SWNT), Double wall (DWNT), Multiwall (MWNT), alligned/tangled/dispersable, OH, COOH functionalized SWNT/MWNT, industrial grade SWCNTs, MWCNTs, conducting (metallic) and semiconducting SWCNTs, MWCNT, nonwoven Papers, CNT foam and special application CNTs.
Modification to CNT
Carbon nanotubes can be further modified in numerous ways to get desired material properties by bonding other atoms or molecules covalently to the ends or sidewalls of the nanotube or non-covalently bonded, e.g., by Van der Waals or polarization forces. Thus this doping changes its electronic properties while derivatization can make the CNTs more easily dispersed and/or soluble in liquids.
Suppliers
North American manufacturers focus more on single wall Carbon nanotubes. In Asia and Europe, Japan tops the list and China stands second in the production of multi wall Carbon nanotubes . Showa Denko, Mitsui and Hodogaya Chemical are among the largest suppliers. Many of the nanotubes marketed by the suppliers are incorporated into transparent conductive films for the display and touch panel industries. Nanotubes are sold to select customers as powders and in suspensions in liquids, also called inks.
Cheap production, purification and separation of conducting and semiconducting nanotubes of selective and uniform size with specific diameter, length and electrical properties is yet to be completely achieved in commercial scale.