Change search
ReferencesLink to record
Permanent link

Direct link
Ionic liquid lubrication: influence of ion structure, surface potential and sliding velocity
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
2013 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 35, 14616-14623 p.Article in journal (Refereed) Published
Abstract [en]

Colloid probe atomic force microscopy (AFM) has been employed to investigate the nanotribology of the ionic liquid (IL)-Au(111) interface. Data is presented for four ILs, 1-ethyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate ([EMIM] FAP), 1-butyl-3-methylimidazolium tris(pentafluoroethyl)-trifluorophosphate ([BMIM] FAP), 1-hexyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate ([HMIM] FAP) and 1-butyl-3-methylimidazolium iodide ([BMIM] I), at different Au(111) surface potentials. Lateral forces vary as a function of applied surface potential and ion structure because the composition of the confined ion layer changes from cation-enriched (at negative potentials) to mixed (at 0 V), and to anion-enriched (at positive potentials). ILs with FAP(-) anions all exhibit similar nanotribology: low friction at negative potentials and higher friction at positive potentials. [BMIM] I displays the opposite behaviour, as an I- anion-enriched layer is more lubricating than either the [BMIM](+) or FAP(-) layers. The effect of cation charged group (charge-delocalised versus charged-localised) was investigated by comparing [BMIM] FAP with 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate ([Py-1,Py-4] FAP). [BMIM] FAP is less lubricating at negative potentials, but more lubricating at positive potentials. This indicated that even at positive potentials the cation concentration in the boundary layer is sufficiently high to influence lubricity. The influence of sliding velocity on lateral force was investigated for the [EMIM] FAP-Au(111) system. At neutral potentials the behaviour is consistent with a discontinuous sliding process. When a positive or negative potential bias is applied, this effect is less pronounced as the colloid probe slides along a better defined ion plane.

Place, publisher, year, edition, pages
2013. Vol. 15, no 35, 14616-14623 p.
Keyword [en]
Atomic-Force Microscopy, Double-Layer Structure, In-Situ Stm, Room-Temperature, Perfluoropolyether Lubricants, Tribological Properties, Ethylammonium Nitrate, Frictional-Properties, Electrode Interface, Chain-Length
National Category
Physical Sciences Chemical Sciences
URN: urn:nbn:se:kth:diva-128506DOI: 10.1039/c3cp52638kISI: 000323196800007ScopusID: 2-s2.0-84882397283OAI: diva2:647948
Swedish Research CouncilSwedish Foundation for Strategic Research

QC 20130913

Available from: 2013-09-13 Created: 2013-09-12 Last updated: 2013-09-13Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Rutland, Mark W.
By organisation
Surface and Corrosion Science
In the same journal
Physical Chemistry, Chemical Physics - PCCP
Physical SciencesChemical Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 66 hits
ReferencesLink to record
Permanent link

Direct link