Early-Stage Wear of Polymer Surfaces and Layered Materials Scraped by a Nanotip

In this chapter we describe two representative applications of atomic force microscopy to investigating early-stage wear on polymeric surfaces and layered materials on the nanoscale. Ripples and exfoliated flakes or chips are the most typical surface structures obtained in each case. On polymers the ripple formation can be interpreted within the Prandtl-Tomlinson mechanism for atomic-scale friction with the evolving surface profile defining the energy landscape sensed by the scanning probe. If the scratching is repeated, nanoplastic particles are extruded from the crests of the ripples and displaced from the places where they were formed. Layered materials are exfoliated all along the scanned track, with the wear products either folded or bent depending on the thickness of the worn material. On multilayer surfaces, but not on monolayers, stick–slip is also observed in the friction force signal acquired while scratching.