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O: Fachverband Oberflächenphysik

O 9: Nanotribology

O 9.3: Vortrag

Montag, 11. März 2013, 11:00–11:15, H42

Unraveling and eliminating dissipation mechanisms in contacts of polymer-bearing surfaces — •Sissi de Beer and Martin H. Müser — Jülich Supercomputing Centre, Institute for Advanced Simulation, FZ Jülich, Jülich, Germany

Polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a high normal load while maintaining low friction at the interface. Depending on the contact-geometry, direction of motion and brush characteristics, different dissipation mechanisms dominate the friction forces. For example, in a parallel plate geometry the interdigitation of the opposing polymers determines the lubricity, while for spherical star polymers in relative motion, viscoelastic deformation governs the energy dissipation. We discuss the relative importance of the dissipation channels for real contacts and show via molecular dynamics simulations that, by using an asymmetric contact of a hydrophobic and hydrophilic polymer-bearing surface, the important dissipation-mechanisms - interdigitation and capillary break-up - can be eliminated. This can reduce friction by a few orders of magnitude compared to a symmetric contact. Our proposed system therefore holds great potential for applications in industry.