Sliding on a Nanotube: Interplay of Friction, Deformations and Structure

Abstract

The frictional properties of individual carbon nanotubes (CNTs) are studied by sliding an atomic force microscopy tip across and along its principle axis. This direction-dependent frictional behavior is found to correlate strongly with the presence of structural defects, surface chemistry, and CNT chirality. This study shows that it is experimentally possible to tune the frictional/adhesion properties of a CNT by controlling the CNT structure and surface chemistry, as well as use friction force to predict its structural and chemical properties.

Adhesion and size dependent friction anisotropy in boron nitride nanotubes

“…In a previous study it was shown that even for very different types of nanotubes the friction anisotropy as a function of α was approximately always following the same analytical curve [12]. Thus, here we will be able to calculate α for each BN-NT with a given friction anisotropy.…”

“…Next, we fit the friction data obtained for different BN-NTs with equation (1) The measured maximum and minimum friction anisotropy (a), average transverse and longitudinal shear strengths (σT , σL (GPa)), coupling parameter (α), intrinsic shear strength (σ int (GPa)) and "hindered rolling" shear strengths (σ HR (GPa)) of BN-NTs as well as the C-NTs from Ref. [12]. than σ L , which varies between 0.02 ± 0.001 and 0.1 ± 0.01 GPa.…”

Morphology-dependent load transfer governs the strength and failure mechanism of carbon nanotube yarns

“…To relate the contact area to the normal van der Waals adhesion force (Fn), and the static friction force (Fs) of CNT-CNT contact (Equations 6 and 7), we must know the contact strength. Previous studies employed molecular dynamics simulations and atomic force microscopy experiments to determine that CNT-CNT contact in shear can be represented by a single asperity microscale friction law 28,29 Here, A is the Hamaker's constant, d is the separation between the outer walls of the CNTs, w and Lc are the contact width and length respectively.…”

“…Therefore, in nominal simulations we use τ = 0.24 GPa as the interfacial shear strength for relative sliding between CVD grown CNTs. 29 In general, the interfacial shear strength depends on factors such as CNT roughness, chirality, presence of other chemical groups and defect density.…”

Measuring the Elasticity of Ribonucleotide(s)-Containing DNA Molecules Using AFM

“…It is found that ds RNA are softer compared to ds DNA with similar contour length due to the existence of nicks along the RNA chain. AFM, in particular, is a powerful technique to study the elasticity of nano-systems [44][45][46][47][48], and ds DNA shorter than hundred nanometers have been investigated using AFM [49][50][51][52][53]. Remarkably, these short ds DNAs have been recently found to be much softer than few kilo base pair DNAs by means of AFM [50,52], X-ray diffraction [54,55], and fluorescence resonance energy transfer (FRET) [55] techniques.…”