Interfacial-bubbling-induced Nondestructive Expansion to Reconstruct Superstrong and Multifunctional Carbon Nanotube Fibers

The severe challenge in ordering carbon nanotubes (CNTs) has become one of the key obstacles in developing high performance CNT fibers. Herein, a nondestructive straightening and multi-functionalization strategy is developed based on an interfacial-bubbling-induced expansion to CNT networks. By activating an electrolysis process in an acid solution, hydrogen bubbles are generated and evolved within the interior of CNT network, leading to an extremely large and uniform expansion, with the lateral size increased by more than two orders of magnitude. The expansion is found to be governed by a force balance between the liquid pressing, surface tension of bubble, and confining force from the network. The expanded CNT networks can be converted into highly aligned and densified fibers with a tensile strength up to 5.18 GPa, after continuous stretching and densification. They are also excellent scaffolds for multifunctional composites. By in situ impregnating polyethylene glycol during the expansion, robust composite fibers with the abilities of electro-thermal conversion and phase change energy storage are produced. (c) 2021 Elsevier Ltd. All rights reserved.