Special CPM Seminar

Molecular mechanisms of lubrication

Roland Bennewitz

INM - Leibniz Institute for New Materials

Lubrication is the reduction of friction forces by means of molecules separating the surfaces in sliding contacts. We investigate molecular mechanisms of lubrication by means of high-resolution force microscopy. An example for solid lubrication is the mechanical protection of platinum crystals by graphene [1]. When liquids are confined to gaps with a size of few molecular diameters, density correlations lead to ordering normal to the confining surfaces. We have developed a dynamic shear force microscopy to measure the shear viscosity of model lubricants in such layered confinement [2]. Ionics liquids are a new class of lubricants with promising properties, in particular electrical conductivity and vanishing vapor pressure. Surface attachment of anion or cation layers can be controlled by electrochemical potentials, opening a pathway to switch friction by applying a potential [3].

References:
[1] A Klemenz, L Pastewka, S G Balakrishna, A Caron, R Bennewitz, and M Moseler, Nano Letters 14 (2014) 7145.
[2] M.-D Krass, N N Gosvami, R W Carpick, M H M�ser, and R Bennewitz, Journal of Physics: Condensed Matter 28 (2016) 134004.
[3] J Sweeney, F Hausen, R Hayes, G B Webber, F Endres, M W Rutland, R Bennewitz, and R Atkin, Physical Review Letters 109 (2012) 155502.