1. Field of the Invention
The invention relates generally to carbon nanotube films and, particularly, to a method for making a carbon nanotube film.
2. Discussion of Related Art
Carbon nanotubes (CNTs) produced by means of arc discharge between graphite rods were first discovered and reported in an article by Sumio Iijima, entitled “Helical Microtubules of Graphitic Carbon” (Nature, Vol. 354, Nov. 7, 1991, pp. 56-58). CNTs are electrically conductive along their length, chemically stable, and capable, individually, of having a very small diameter (much less than 100 nanometers) and large aspect ratios (length/diameter). Due to these and other properties, it has been suggested that CNTs can play an important role in various fields, such as field emission devices, new optic materials, sensors, soft ferromagnetic materials, etc.
Carbon nanotube film has been found especially useful in field emission electron sources, photoelectric and biological sensors, transparent electrical conductors, battery electrodes, absorbing materials, water purification materials, light emitting material, and related devices. Thus, methods for making the carbon nanotube film have been become the basis for applications in the above-described fields. Currently, carbon nanotube film can be made by a method of direct growth.
Moreover, the carbon nanotube film can also be made by methods using carbon nanotube powders, such as a dropping and drying solvent method, a Langmuir-blodgett (L-B) method, a printing method, an electrophoresis method, a membrane filter method, etc. However, the above-described methods generally have complicated fabrication procedures. Thus, in use, such methods have proven less efficient than truly desirable. Furthermore, the carbon nanotube films produced by the above-described methods have poor tensile strength and/or toughness. Thus, the carbon nanotube films are susceptible to fracture.
What is needed, therefore, is a method for making a carbon nanotube film, that is very simple, efficient, and produces a film whose toughness is excellent.