Simulation of Nanoscale Peeling and Adhesion of Single-Walled Carbon Nanotube on Graphite Surface

• Published in: E-journal of surface science and nanotechnology Vol. 6; pp. 72 - 78
• Main Authors: Sasaki, Naruo, Toyoda, Arihiro, Itamura, Noriaki, Miura, Kouji
• Format: Journal Article
• Language: English
• Published: Tokyo The Japan Society of Vacuum and Surface Science 01.01.2008; Japan Science and Technology Agency
• Subjects: Adhesion; Atomic force microscopy; Carbon nanotube; Computer simulations; Molecular mechanics simulations; Peeling; Physical adsorption; Theory of elasticity
• ISSN: 1348-0391; 1348-0391
• DOI: 10.1380/ejssnt.2008.72

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 bistable states between the line- and point-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 on the order of CNT's length (≈ 100 Å) and atomic-scale mechanics on the order of CNT's diameter (≈ several Å). The deflection of CNT along z direction for some regions can be well explained by theory of elasticity. Next the effect of the CNT length l on the peeling process is studied. As the CNT becomes shorter, discrete jump of the force curve vanishes and the peeling force curve exhibits continuous behavior because the shorter CNT has larger spring constant k_z along the vertical direction. The length l dependence of k_z in the present simulation exhibits k_z ∝ l-2.98, which is in good agreement with theory of elasticity, k_z ∝ l -3. 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 slight difference of the adhesive behavior among different chirality of CNTs. [DOI: 10.1380/ejssnt.2008.72]