The Beilstein Symposium „Molecular Mechanisms in Tribology“ took place on Oct 2-4, 2018, in Potsdam. At Lake Griebnitzsee, 68 scientists from Europe and all over the world discussed mechanisms of friction and wear with an emphasis on molecular structure in sliding contacts and tribochemical reactions. The symposium comprised 20 excellent invited talks and two poster sessions with contributions of outstanding quality. The contributions and vivid discussions after talks, during the poster sessions, and in the evenings made the symposium a success.
Two main areas of research structured the content of the symposium: on the one hand studies on the role of the molecular structure for friction and wear and on the other hand studies of chemical reactions activated by shear in sliding contacts.
Fundamental studies of the structural dynamics at the molecular scale and related pathways of dissipation were presented by Nicola Manini (Milano) and Michael Urbakh (Tel Aviv). The latter reported on the emergence of friction anisotropy only in the dynamics of structural lubricity between layered materials. The role of water in lubrication was subject of several talks. Roland Netz (Berlin) explained how a careful treatment of the chemical potential of water molecules in simulations allows to predict the transition from hydrodynamic lubrication to boundary slip. The interaction of hydrated ions with hydrophobic surfaces and its role in lubrication was explored in experiments reported by Rosa Espinoza-Marzal (Urbana-Champaign). Nuria Espallargas (Trondheim) explained her progress in replacing oil-based lubricants in applications in contact with sea water by water-based molecular functionalization of the contacting surfaces. The change in friction due to water intercalation in layered materials was related to phonon density effects through an isotope experiment by Jeong Park (Daejeon). Collective effects on the friction of molecular assemblies were discussed by Romain Lhermerout (Oxford) for C60 molecules jammed in confinement, by Juliette Cayer-Barrioz (Lyon) for time-scales of relaxation in discontinuous sliding, and by Seong Kim (Penn State) who provided a thoughtful review on the relation between the molecular volume and the activation volume in stress-assisted processes. Novel molecular designs with tribological functions were introduced by Bart Weber (Amsterdam) for fluorescent molecules reporting their nanometer confinement, by Sissi de Beer (Twente) for lubricant molecules attached to syringe needles, and by Nicholas Spencer (Zürich) for looped polymers grafted to surfaces.