The effect of anion architecture on the lubrication chemistry of phosphonium orthoborate ionic liquids.

Autor: Munavirov B; System and Component Design, KTH Royal Institute of Technology, 100 44, Stockholm, Sweden., Black JJ; School of Chemistry, University of New South Wales, UNSW Sydney, Sydney, NSW, 2052, Australia., Shah FU; Chemistry of Interfaces, Luleå University of Technology, 97 187, Luleå, Sweden., Leckner J; Axel Christiernsson International AB, 44911, Nol, Sweden., Rutland MW; School of Chemistry, University of New South Wales, UNSW Sydney, Sydney, NSW, 2052, Australia. mark@kth.se.; Division of Surface and Corrosion Science, KTH Royal Institute of Technology, 100 44, Stockholm, Sweden. mark@kth.se.; Surfaces, Processes and Formulation, RISE Research Institutes of Sweden, 100 44, Stockholm, Sweden. mark@kth.se., Harper JB; School of Chemistry, University of New South Wales, UNSW Sydney, Sydney, NSW, 2052, Australia. j.harper@unsw.edu.au., Glavatskih S; System and Component Design, KTH Royal Institute of Technology, 100 44, Stockholm, Sweden. segla@kth.se.; School of Chemistry, University of New South Wales, UNSW Sydney, Sydney, NSW, 2052, Australia. segla@kth.se.; Department of Electromechanical, Systems and Metal Engineering, Ghent University, 9052, Ghent, Belgium. segla@kth.se.
Jazyk: angličtina
Zdroj: Scientific reports [Sci Rep] 2021 Dec 15; Vol. 11 (1), pp. 24021. Date of Electronic Publication: 2021 Dec 15.
DOI: 10.1038/s41598-021-02763-5
Abstrakt: Phosphonium ionic liquids with orthoborate anions have been studied in terms of their interfacial film formation, both physisorbed and sacrificial from chemical breakdown, in sheared contacts of varying harshness. The halogen-free anion architecture was varied through (i) the heteronuclear ring size, (ii) the hybridisation of the constituent atoms, and (iii) the addition of aryl functionalities. Time of Flight-Secondary Ion Mass Spectrometry analysis revealed the extent of sacrificial tribofilm formation allowing the relative stability of the ionic liquids under tribological conditions to be determined and their breakdown mechanisms to be compared to simple thermal decomposition. Overall, ionic liquids outperformed reference oils as lubricants; in some cases, sacrificial films were formed (with anion breakdown a necessary precursor to phosphonium cation decomposition) while in other cases, a protective, self-assembly lubricant layer or hybrid film was formed. The salicylate-based anion was the most chemically stable and decomposed only slightly even under the harshest conditions. It was further found that surface topography influenced the degree of breakdown through enhanced material transport and replenishment. This work thus unveils the relationship between ionic liquid composition and structure, and the ensuing inter- and intra-molecular interactions and chemical stability, and demonstrates the intrinsic tuneability of an ionic liquid lubrication technology.
(© 2021. The Author(s).)
Databáze: MEDLINE
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