Single Polymer Friction at Interfaces

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Friction at interfaces is dominated by processes that dissipate kinetic energy. For friction between two solid substrates this can be lattice vibrations, plasmons, or phonons. The mechanisms for single polymers on solid substrates are still unknown.The aim of this project is an understanding of polymer friction on solid substrates in aqueous environment. We will utilize the AFM-based single polymer probes developed in the last proposal to pull polymers laterally across surfaces. A variation of velocities, hydrophobicity, charge, topography and temperature of the interaction partners and the solvent will help to delineate the dissipation mechanisms. In addition, we will measure if Amonton’s law holds at the nano-scale and how adhesion contributes to the normal force. The experiments will be complemented by the tracking of fluorescently marked single polymers to learn how nonequilibrium and equilibrium friction are related for polymers at interfaces. We should even be able to gain new insights into lubrication and wear.