Polyimide Aerogels as Lightweight Dielectric Insulators for Carbon Nanotube Cables

Replacing copper as the central conductor with carbon nanotube (CNT) yarn has potential for greatly reducing the weight of data and power cables for any number of aerospace and automotive applications. Polyimide aerogels, with lightweight and low dielectric constants approaching one, have promise to even further reduce the weight of the cable as the dielectric insulation layer. In this paper, polyimide aerogels containing 4,4′-bis(4-aminophenoxy)biphenyl (BAPB) in the backbone and two different cross-linkers (1,3,5-triaminophenoxybenzene, TAB, or poly(isobutylene-alt-maleic anhydride), PMA-D) were examined as potential coatings on CNT yarns. The effects of polyimide concentration and different solvent combinations on the quality of the coating were also examined. The best quality coatings were obtained with aerogels made by using PMA-D as the cross-linker, high polymer concentration, and a mixture of solvents. This work demonstrates the feasibility of using polyimide aerogels as the dielectric layer for lightweight CNT data and power cables. More improvements need to be made in the future, including scale up of the coating process, coating quality, and durability.