Robust carbon nanotube composite fibers: Strong resistivities to protonation, oxidation, and ultrasonication

Carbon nanotube (CNT) fibers have great potential in the field of high performance fibers. However, poor inter-tube coupling between bundles resulting in low structural and mechanical stability under strong acid, ultrasonication and high-temperature oxidation limited the practical applications of CNT fibers in extreme environment. Here we report the preparation of robust carbon nanotube/carbon (CNT/C) composite fibers with highly aligned and dense structure utilizing an ultrafast Joule heating tension-annealing approach. CNT fibers prepared by floating catalytic chemical vapor deposition were infiltrated by polyacrylonitrile (PAN) solution, followed by programable tension annealing in argon for 10 s. Such a short process carbonized infiltrated PAN, resulting in the formation of CNT/C fibers within which CNTs were bonded by pyrolytic carbon. Due to the carbon-bonded structure, the composite fibers exhibited improved resistivity against structure damages when exposed to strong acid, ultrasonication, and high-temperature oxidation. Comparing with the pristine CNT fibers, such composite fibers showed 320% improvement in breaking load, 354% increase in strength (2.3 GPa) and 667% increase in modulus (60 GPa), respectively. Moreover, such composite fibers have low densities (1.48 g/cm³) and excellent flexibility and toughness. These combined features could broaden the application of the CNT/C composite fibers in many areas.