Science 339, 182–186 (2013)

Credit: © 2013 AAAS

Single carbon nanotubes (CNTs) have shown outstanding mechanical, thermal and electrical properties that are difficult to reproduce on the macroscopic level. Because of severe limitations in large-scale manufacturing protocols, CNT fibres fail to fulfil the expected strength of carbon fibres as well as the thermal and electrical conductivities of metals. Natnael Behabtu and colleagues now demonstrate that, by using highly purified CNTs that are ten times longer than those currently used, fibres with unprecedented multifunctional performance can be produced using the well-known wet-spinning technology. A highly ordered texture reaching a packing fraction of 90% improves their tensile strength compared with wet-spun fibres made using other approaches. This morphology, combined with iodine doping and annealing steps, also favours inter- and intra-CNT electrical transport as well as thermal conductivity. The researchers also foresee that the properties of the fibres will get closer to those of single CNTs when even longer and defect-free CNTs will be available for industrially scalable wet-spinning processes.