Observation of Nanometer-Scale Rolling Motion Mediated by Commensurate Contact

TL;DR

This study demonstrates that atomic lattice interlocking at the nanoscale can determine whether a nanomaterial rolls or slides on a surface, with experimental and simulation evidence showing rolling occurs only on graphite due to lattice registry.

Contribution

It provides the first combined experimental and computational analysis of lattice-mediated rolling versus sliding at the nanometer scale, revealing atomic-scale mechanisms.

Findings

Rolling occurs only on graphite due to lattice interlocking.

Force measurements correlate with atomic registry between CNTs and substrate.

Simulations identify energy barriers and atomic features influencing motion.

Abstract

We report, through experimental observations and computer simulations, that atomic lattice interlocking can determine whether an object rolls or slides on a surface. We have quantitatively manipulated carbon nanotubes (CNTs) on a variety of substrates with an atomic force microscope (AFM) and observe rolling to occur only on graphite. We measure the forces when the CNT is in-registry with the graphite lattice, and observe rolling only in this lock-in state. Atomistic computer simulations identify the energy barriers for sliding and rolling, elucidate atomic-scale features of slip-roll motion, and explain the details of the lateral force data in terms of the intrinsic faceting of multiwall CNTs.