Pullout behavior of large-diameter collapsed double-walled carbon nanotubes

The pullout behavior of large-diameter collapsed double-walled carbon nanotubes (DWCNT) was studied by molecular dynamics simulations and compared with those in the circular cross-sectioned state. The pullout force-displacement curves of both are in good agreement with the same mean value of the pullout force during the steady pullout stage. The pullout force was mainly due to the formation of new surfaces; the friction between nested walls was negligible. The effects of different chiral combinations and inter-wall spacings on the pullout behavior for both section situations were investigated. The commensurate (zigzag/zigzag or armchair/ armchair) bi-tube systems have a larger fluctuation in the pullout force. The smaller interspacing implies lower mean pullout force with stronger fluctuations.