Twisting of single-walled carbon nanotube bundles

Bundles of single-walled carbon nanotubes produced by laser ablation are often seen twisted in morphology, forming nanoropes which would better suit the function for improvement of structural stability in mechanical applications. The rope-like configuration is explained with a model that relates the twisting morphology to the helicity difference between the neighboring nanotubes. This self-assembly phenomenon is attributed to the fact that a twisted structure has lower total energy compared with the raft-like parallel bundles when the helicities of neighboring nanotubes are different.