Nano-scale friction and wear of polymer coated with graphene

Background: Friction and wear of polymers at the nano scale is a challenging problem due to the complex viscoelastic properties and structure. Using molecular-dynamics simulations, we investigate how a graphene sheet on top of a semicrystalline polymer (PVA) affects the friction and wear. Results: : Our setup is meant to resemble an AFM experiment with a silicon tip. We have used two different graphene sheets: an unstrained, flat sheet, and one that has been crumpled before being deposited on the polymer. Conclusion: The graphene protects the top layer of the polymer from wear and reduces the friction. The unstrained flat graphene is stiffer, and we find that it constrains the polymer chains and reduces the indentation depth.