Phosphonium Ionic Liquids (Pils) In Lubrication

Part 4: CYPHOS® IL 104

In the last several blogs we focused on trihexyl(tetradecyl)phosphonium bis(trifluoromethanesulfonyl)amide aka CYPHOS® IL 109 (CAS # 460092-03-9, Strem: 15-6370, 96-6520, Ionic Liquid Kit 3: CYPHOS® IL Phosphonium Salt Kit) in lubrication [1-3].

This time we would like to talk about another PIL based on trihexyl(tetradecyl)phosphonium cation, namely, trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate aka CYPHOS® IL 104 (CAS # 465527-59-7, Strem: 15-6374, 96-6520 Ionic Liquid Kit 3: CYPHOS® IL Phosphonium Salt Kit) [4]:

CYPHOS® IL 104 is a developmental ionic liquid made from commercially available CYPHOS® IL 101 [5] and CYANEX® 501[6]. The preparation ofCYPHOS® IL 104 was originally reported in [7-8] and its NMR characterization was also reported in [8].

Four phosphonium-based ILs were studied in [9]. Some of them, including CYPHOS® IL 104, showed excellent miscibility with non-polar hydrocarbon oils such as mineral based oil SAE 10W and synthetic PAO. CYPHOS® IL 104 had an exceptionally high thermal stability with the onset of decomposition being 366 ⁰C, the highest among the four PILs studied. Also, CYPHOS® IL 104 showed no corrosive attack to non-protected metals such as grey cast iron or cast aluminum 319 at either room or elevated temperature (135 ⁰C) over a period of 7 days. Initial tribological evaluation demonstrated significant friction and wear reductions from adding a small amount (e.g., 5 wt%) of CYPHOS® IL 104 into a base oil. Results suggested great potential for the oil-miscible PILs, including CYPHOS® IL 104, as lubricant additives.

The miscibility and anti-wear performance of various phosphonium (including CYPHOS® IL 104), imidazolium, and pyrrolidinium ionic liquids in a range of polar and nonpolar base oils for steel on aluminum was studied in [10]. The largest reductions in wear at the highest load tested were found for a mineral oil/ CYPHOS® IL 104 blend.

Two phosphonium cation-based ionic liquids, including CYPHOS® IL 104, were tested as lubricant additive at three concentrations (0.25, 0.5 and 1 wt%) fulfilling the phosphorus concentration limits imposed for motor oils by ILSAC GF-5. Mixtures of the base oil using ZDDP as additive reaching equivalent phosphorus concentrations to that obtained with the ionic liquids were also tested as comparative samples. The CYPHOS® IL 104 - containing mixtures outperformed the anti-wear behavior of the other samples [11].

In another study, the tribological behavior of two phosphonium-based ILs, including CYPHOS® IL 104, as additives to a bio-oil (BO) was investigated in steel-steel contact for use in wind turbine gearboxes [12]. Adding CYPHOS® IL 104 reduced wear volume 68.4% compared to the base BO. Addition of halogen-containing (and more expensive) CYPHOS® IL 109 resulted in wear reduction of 74.3% with respect to the base BO.

We have briefly reviewed just a handful of publications on the testing of phosphonium phosphinate ionic liquid CYPHOS® IL 104 in lubrication. More publications of interest on this subject matter were published after 2016 and we will make an effort to review those publications as well in subsequent blogs. Stay tuned!

References:

1. Phosphonium Ionic Liquids in Lubrication. Part 1: CYPHOS® IL 109
2. Phosphonium Ionic Liquids in Lubrication. Part 2: CYPHOS® IL 109
3. Phosphonium Ionic Liquids in Lubrication. Part 3: CYPHOS® IL 109
4. CYPHOS® IL 104
5. CYPHOS® IL 101
6. CYTOP® 501
7. WO2002079212
8. Green Chem. 2003, 5, 2, 143-152.
9. Wear, 2012, 289, 58-64.
10. ACS Appl. Mater. Interfaces, 2013, 5, 22, 11544-11553.
11. Tribology International, 2016, 98, 82-93.
12. Wear, 2017, 376-377 (Part A), 756-765.

Featured Products

15-6370 Trihexyl(tetradecyl)phosphonium bis(trifluoromethanesulfonyl)amide, min. 97% CYPHOS® IL 109 (460092-03-9)

15-6374 Trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate, min. 90% CYPHOS® IL 104 (465527-59-7)

96-6520 Ionic Liquid Kit 3: CYPHOS® IL Phosphonium Salt Kit