Double‐Walled Carbon Nanotubes with Dynamic Strength of over 90 GPa Enhanced by Intershell Friction

Abstract

AbstractLow‐dimensional ultra‐strong nanomaterials have attracted great anticipation for applications under extreme dynamic conditions. A photocatalytic method is developed to selectively cut off the outer shell of double‐walled carbon nanotubes (DWCNTs), achieving non‐contact measurement of intershell friction with both high temporal and spatial resolutions at high sliding velocities under optical microscope. The intershell friction linearly increases with the sliding velocity, with a slope related to intershell distance and chirality of DWCNTs. The maximum measured friction reaches 194.1 ± 7.3 nN at a sliding velocity of 977 mm s−1, a value comparable to the tensile force (≈450 nN) for breaking the outer shell. Molecular dynamics simulations indicate that the velocity‐dependent intershell friction is related to dynamic localized commensurate contacts. The friction‐induced “intershell locking” enhances the effective dynamic strength of DWCNTs from 64.8 ± 3.4 GPa to 90.1 ± 4.0 GPa at a tensile strain rate of 3300 s−1. This study reveals anomalous friction mechanisms at nanoscale and demonstrates promising application of DWCNTs as ultra‐strong materials.