Mechanical peeling of free-standing single-walled carbon-nanotube bundles.

An in situ electron microscopy study is presented of adhesion interactions between single-walled carbon nanotubes (SWNTs) by mechanically peeling thin free-standing SWNT bundles using in situ nanomanipulation techniques inside a high-resolution scanning electron microscope. The in situ measurements clearly reveal the process of delaminating one SWNT bundle from its originally bound SWNT bundle in a controlled-displacement manner and capture the deformation curvature of the delaminated SWNT bundle during the peeling process. A theoretical model based on nonlinear elastica theory is employed to interpret the measured deformation curvatures of the SWNTs and to quantitatively evaluate the peeling force and the adhesion strength between bundled SWNTs. The estimated adhesion energy per unit length for each pair of neighboring tubes in the peeling interface based on our peeling experiments agrees reasonably well with the theoretical value. This in situ peeling technique provides a potential new method for separating bundled SWNTs without compromising their material properties. The combined peeling experiments and modeling presented in this paper will be very useful to the study of the adhesion interactions between SWNTs and their nonlinear mechanical behaviors in the large-displacement regime.