Electrotunable Lubricity with Ionic Liquid Nanoscale Films

O. Y. Fajardo, F. Bresme, A. A. Kornyshev, M. Urbakh*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

88 Scopus citations

Abstract

One of the main challenges in tribology is finding the way for an in situ control of friction without changing the lubricant. One of the ways for such control is via the application of electric fields. In this respect a promising new class of lubricants is ionic liquids, which are solvent-free electrolytes, and their properties should be most strongly affected by applied voltage. Based on a minimal physical model, our study elucidates the connection between the voltage effect on the structure of the ionic liquid layers and their lubricating properties. It reveals two mechanisms of variation of the friction force with the surface charge density, consistent with recent AFM measurements, namely via the (i) charge effect on normal and in-plane ordering in the film and (ii) swapping between anion and cation layers at the surfaces. We formulate conditions that would warrant low friction coefficients and prevent wear by resisting 'squeezing-out' of the liquid under compression. These results give a background for controllable variation of friction.

Original languageEnglish
Article number7698
JournalScientific Reports
Volume5
DOIs
StatePublished - 9 Jan 2015

Funding

FundersFunder number
DIP
German-Israeli Project Cooperation Program
TAU Center for Nanoscience and Nanotechnology
Engineering and Physical Sciences Research CouncilEP/H004319/1, EP/J003859/1, EP/K039946/1
European Cooperation in Science and TechnologyMP1303
Israel Science Foundation1316/13

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