Coupled Evolution of Sliding and Rolling of Carbon Nanotubes: Effect of Lattice Mismatch and Size

The lattice mismatch and size effect of carbon nanotubes (CNTs) are essential for the sliding and rolling of CNTs. However, it still presents a significant challenge to understand and quantify the impacts of lattice mismatch and size effect of CNTs on nanofriction. To address this issue, we studied the rolling and sliding of nonperiodic CNTs on graphene and hexagonal boron nitride (hBN) using molecular dynamics method on the basis of reparametrized interlayer potential. We find that the increased length of CNTs makes the motion of CNTs transition from integral rolling to domino-like sliding on graphene and the lattice mismatch effectively reduces the length of rolling-sliding (R-S) transition, while the R-S transition disappears on hBN due to the distinct properties of substrates. In addition, the sliding friction force depends on lattice mismatch but not on the length of CNTs, while the rolling friction force depends on both the lattice mismatch and length of CNTs. These results allow us to establish a simple model based on the Prandtl- Tomlinson model to understand the underlying mechanism, which provides a novel physical picture about the lattice mismatch and size effect of CNTs in the nanofriction.

Automated summary

The lattice mismatch and size effect of carbon nanotubes (CNTs) have significant impacts on nanofriction. Molecular dynamics simulations reveal that longer CNTs transition from rolling to sliding on graphene, and the lattice mismatch reduces the length of rolling-sliding transition. However, this transition is absent on hexagonal boron nitride (hBN) due to its distinct properties. Sliding friction force depends on lattice mismatch, while rolling friction force depends on both lattice mismatch and CNT length.