Influences of out-of-plane elastic energy and thermal effects on friction between graphene layers

Through molecular dynamic simulations, a system for investigating the contributions of elastic deformation energy and thermal activation effects to friction has been constructed. In this system, a graphene flake slides on a suspended graphene layer anchored on a bed of springs. The “graphene–spring” system provides a useful ideal approach to model different layers of graphene through changing the stiffness of the springs. The results first indicate that both the friction force and the elastic deformation energy have an exponential dependence on the support stiffness. Second, the observed non-monotonic variation in friction manifested by peaks and plateaus with increasing temperature results from the changing rate of energy dissipation due to the transition of slip regimes. Therefore, we suggest that the friction force emanates from the competition between the interfacial energy barrier and out-of-plane elastic deformation energy, as well as the competition between the thermal activation effects and transition of slip regimes. Therefore, the observation can extend the validity of the Prandtl–Tomlinson model on friction phenomena. Our simulations are intended to provide theoretical guidance when considering the influence of stiffness on the friction between graphene layers in the design of nanodevices.