Enhancement of the mechanical properties of directly spun CNT fibers by chemical treatment.

Translating the remarkable mechanical properties of individual carbon nanotubes to macroscopic assemblies presents a unique challenge in maximizing the potential of these remarkable entities for new materials. Infinitely long individual nanotubes would represent the ideal molecular building blocks; however, in the case of length-limited nanotubes, typically in the range of micro- and millimeters, an alternative strategy could be based on the improvement of the mechanical coherency between bundles assembling the macroscopic materials, like fibers or films. Here, we present a method to enhance the mechanical performance of fibers continuously spun from a CVD reactor, by a postproduction processing methodology utilizing a chemical agent aided by UV irradiation. The treatment results in an increase of 100% in specific strength and 300% in toughness of the fibers with strength values rocketing to as high as 3.5 GPa SG(-1). An attempt has been made to explore the nature of the chemical modifications introduced in the fiber and the consequential effects on its properties.