| Wed January 7th 2015 16:00 – 17:00 ZH286 | Seminar | Unraveling and eliminating dissipation mechanisms in contacts of polymer-bearing surfaces Sissi de Beer |
Details:Polymer brushes are well known to lubricate high-pressure contacts, while they can keep a low-viscosity solvent in the contact, even at high normal loads. However, interdigitation of the polymers on the opposing surfaces can increase friction and result in wear due to scission and chain pull out. I will present a simple method to eliminate interdigitation. To do so, we have setup an asymmetric contact of two immiscible polymer brush systems in both molecular dynamic simulations and atomic force microscopy experiments. For such immiscible polymer brush systems, we find that friction upon sliding is a few orders of magnitude lower than for symmetric miscible contacts and also wear of the coating is strongly reduced. Moreover, depending on the contact-geometry, direction of motion and brush characteristics, alternative dissipation channels dominate the friction forces. I will discuss the relative importance of the dissipation channels for realistic, rough surfaces and I will show how we can use this knowledge to control adhesion and friction in polymer brush contacts. | ||
