Conjugationally cross-linking carbon nanotube film for high electrical conductivity and stability

Individual carbon nanotube (CNT) can be metallically conductive. However, the electrical conductivities of CNT assemblies, such as fibers, sheets or buckypapers that are made of individual nanotubes, are much lower than their constitutes. The major reason is that the intertube resistance is much greater than nanotube intrinsic resistance due to the lack of an effective electron conductive pathways from nanotube to nanotube. This paper reports on research in which nanotubes were conjugationally cross-linked via chemical modification and polymerization. Conjugation of ene-yne backbones with nanotubes of the crosslink structures created effective 3-D electron transfer paths within the nanotube networks. The inter-connected nanotube sheets demonstrated an electrical conductivity of 6200 S cm-1, which is greater than one order of increase compared to the pristine sheets. The covalent bonding also rendered carbon nanotube sheets excellent doping stability at atmosphere for over 300 hours, and they also were resistant to degradation at elevated temperatures. The results show promise towards fabricating highly conductive, lightweight carbon nanotube assemblies for various applications.