Materials Science and Technology of Polymers

Sissi de Beer won poster prize at ISP 2014

At the Internal Symposium on Polyelectrolytes Sissi de Beer won the poster prize with her poster entitled:
Unraveling and eliminating dissipation mechanisms in polymer brush friction.






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, interdigitation of the opposing polymers determines the lubricity, while for spherical star polymers in relative motion, viscoelastic deformation governs the energy dissipation. On her poster, Sissi discusses the relative importance of the dissipation channels for real contacts. Moreover, she shows via molecular dynamics simulations and atomic force microscopy experiments 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 symmetric contacts. The described system therefore holds great potential for applications in industry.