Improving Electrical Performance of Carbon Nanotube Fibers Using Liquids
Isenhart, Lucas Charles
Barrera, Enrique V
Doctor of Philosophy
Since the discovery of carbon nanotubes in 1991, carbon nanotube-based fibers have been put forth as candidates as a lightweight replacement for metals in electrical wiring. While a tremendous amount of progress has been made in developing these CNT-based fibers for copper replacements, they are still not ready for ubiquitous use. Thus far, the properties of carbon nanotube fibers that are made in industrial quantities typically fall below meticulously-made laboratory samples. Even these small-scale samples fall short of copper’s absolute conductivity value. If copper is to be replaced by an alternative conductor, it is of vital importance that this conductor’s performance equal or exceed copper. In pursuit of this goal, new methods to manipulate the electronic properties of CNTs in a fiber using liquids were investigated. Enhancing conduction using liquids is a nearly unexplored area as liquids have a very limited role in energy transmission. It has been shown that liquids are able to infiltrate the void space inside of several types of carbon nanotube fibers and alter the electrical properties. In so far, this inherent structural feature of CNT fibers has yet to be fully explored in regard to conduction. In this work, the composition, porous structure, and initial electronic properties of direct spun carbon nanotube fibers was obtained. A systematic study showing how solvent properties effect iodine doping in CNT fibers was performed. A novel method of creating liquid proof electrical contacts between CNT fibers and metals was developed. Experiments illuminating the changes in carbon nanotube fiber structure and resistance upon immersion in liquids were performed. And a liquid-phase doping scheme was examined and showed a decrease in fiber resistance as well as an increase in current carrying capacity. These electrical property changes induced by liquids have tremendous potential for large scale improvements. The understanding generated in this project of the effects that liquids have on conduction in carbon nanotube fibers resulted in an increase in the fiber’s electrical performance and will ultimately aid in the implementation of carbon nanotube fibers as conduction wires.
Carbon Nanotubes; Electrical Properties; Liquids