Why orthotropic friction is important on graphene and graphene fluoride thin films

Abstract

We experimentally demonstrate that graphene and graphene fluoride manifest different coefficients of sliding friction at the edges (graphene fluoride from 5.8×10-3 to 4.9×10-1; graphene from 8.2×10-3 to 3.3×10-1) of a sheet sample versus the interior (graphene fluoride from 5.1×10-3 to 1.5×10-1; graphene from 2.5×10-2 to 2.3×10-1) under ambient humidity conditions (~ 40-60%). Atomic force microscopy (AFM) was used to prove the friction coefficients show distinct directional dependence between graphene and graphene fluoride.