Molecular-Mechanics Simulation of Nanoscale Peeling and Adhesion of Carbon Nanotube

Abstract

We have performed molecular mechanics study of nanoscale peeling and adhesion processes of carbon nanotube (CNT) on the rigid graphite surface. First, as a model of CNT, single-walled carbon nanotube (SW-CNT) of the (3, 3) armchair type with a length of l = 99.3 Å comprised of 480 carbon atoms is used. In the simulation CNT physically adsorbed on the graphite substrate is peeled (retracted) from the surface and then adsorbed (approached) onto the surface. We have first obtained the vertical force-distance curve with the characteristic hysteresis loop derived from the quasistabe states between the line- and point- and non-contacts during the peeling and adhesion processes. The analysis of the vertical and lateral force curves reveals that the CNT shows multiscale mechanics — both nanoscale mechanics in the order of CNT's length (≈ 100 Å) and atomic-scale mechanics in the order of CNT's diameter (≈ several Å). The deflection of CNT along z direction and the length l dependence of k_z, k_z ∝ l^−2.98, can be well explained by theory of elasticity. Lastly the effect of the chirarity of the CNT on the peeling and adhesion processes is studied for the armchair, zigzag and chiral type CNTs for the length of about 50 Å. The hysteresis of the peeling curve shows the adhesive behavior derived from the difference of adhesive feature and the free edge structure among different chirality of CNTs.