Continuous carbon nanotube yarns and their applications

Assembling carbon nanotubes (CNTs) into macroscopic structures is of great importance to their applications. Since their discovery much progress has been made in vertically aligning CNT into arrays on substrates, which has found use in field emission display. However, little work has been done on their lateral alignment into continuous CNT yarns or ropes. Here we show a new finding that CNTs can be self－assembled into yarns simply by pulling from super－aligned CNT arrays. In this process the CNT array serves as a cocoon. The pure CNT yarn is made of well－aligned CNT segments that are end－to－end jointed by van der Waals′ interaction. The CNT polarizer extending to the ultraviolet region was implemented by parallel aligning a large multitude of yarns. The yarns were also used as filaments of a light bulb, which emitted incandescent light with low power consumption. Moreover, the strength and the conductivity of the CNT yarns can be considerably enhanced by high temperature treatment, which may further lead to a variety of uses of the yarns at the macroscopic level.