Deformation of nanotubes in peeling contact with flat substrate: An in situ electron microscopy nanomechanical study

Abstract

Peeling of one-dimensional (1D) nanostructures from flat substrates is an essential technique in studying their adhesion properties. The mechanical deformation of the nanostructure in the peeling experiment is critical to the understanding of the peeling process and the interpretation of the peeling measurements, but it is challenging to measure directly and quantitatively at the nanoscale. Here, we investigate the peeling deformation of a bundled carbon nanotube (CNT) fiber by using an in situ scanning electron microscopy nanomechanical peeling technique. A precalibrated atomic force microscopy cantilever is utilized as the peeling force sensor, and its back surface acts as the peeling contact substrate. The nanomechanical peeling scheme enables a quantitative characterization of the deformational behaviors of the CNT fiber in both positive and negative peeling configurations with sub-10 nm spatial and sub-nN force resolutions. Nonlinear continuum mechanics models and finite element simulations are employed to interpret the peeling measurements. The measurements and analysis reveal that the structural imperfections in the CNT fiber may have a substantial influence on its peeling deformations and the corresponding peeling forces. The research findings reported in this work are useful to the study of mechanical and adhesion properties of 1D nanostructures by using nanomechanical peeling techniques. Published by AIP Publishing. [http://dx

Dynamic stiffness of the contact between a carbon nanotube and a flat substrate in a peeling geometry

“…One hypothesis is for example that nanoscale rearrangement or diffusion of defects occur during the strong mechanical solicitation of the contact point (the radius of curvature is typically only 10 times the nanotube diameter 13,14 ). Such defects exist undoubtedly 16 , as shown by the irregularities in the measured quantities along the cantilever length, in the form of fluctuations around the plateaus, or more dramatic force jumps in the force curves. Another hypothesis is that some friction occurs at the contact point, dissipating part of the mechanical energy and leading to delays in the system response.…”

“…The force versus distance curve displays a signature specific to this peeling process, and can be used to extract the energy of adhesion between the nano-object and the surface. Scanning electron microscopy has also been used to substantiate those conclusions by confirming the geometry of the contact during peeling 10,11,15,16 . These peeling experiments are however restricted to the quasi-static mechanical behavior of the contact, since the time scales probed are of the order 1 s. In this article, we explore the dynamic response of the contact, which can be quite different.…”

Dynamic stiffness of the contact between a carbon nanotube and a flat substrate in a peeling geometry

“…The force versus distance curve displays a signature specific to this peeling process, and can be used to extract the energy of adhesion between the nano-object and the surface. Scanning electron microscopy has also been used to substantiate those conclusions by confirming the geometry of the contact during peeling 10,11,15,16 .…”

A numerical-experimental approach towards picomechanics and picotribology: the case study of defective carbon nanotubes bundles

“…various experimental images reproducing other deformed states 25 (see Supplementary Figure S1), thus excluding tilt artifacts.…”