Ionic liquids containing quaternary ammonium and phosphonium cations, and their use as environmentally friendly lubricant additives
An ionic liquid composition having the following generic structural formula: wherein Z is N or P, and R 1 , R 2 , R 3 , and R 4 are independently selected from hydrogen atom and hydrocarbon groups having one to four carbon atoms with optional interconnection to form a cyclic group that includes Z, and wherein R 1 , R 2 , R 3 , and R 4 are all hydrocarbon groups when Z is P, and X − is a phosphorus-containing or carboxylate anion, particularly an organophosphate, organophosphonate, or organophosphinate anion, or a thio-substituted analog thereof containing hydrocarbon groups with at least three carbon atoms. Also described are lubricant compositions comprising the above ionic liquid and a base lubricant, wherein the ionic liquid is dissolved in the base lubricant. Further described are methods for applying the ionic liquid or lubricant composition onto a mechanical device for which lubrication is beneficial, with resulting improvement in friction reduction, wear rate, and/or corrosion inhibition.
1. A lubricant composition comprising:
(i) an ionic liquid selected from the group consisting of:
and
(ii) a base lubricant selected from the group consisting of polyalkylene glycols, vegetable oils, synthetic ester oils, polyalphaolefins, and water;
wherein said ionic liquid is dissolved in said base lubricant and is included in said lubricant composition in a concentration in a range of 0.1-5 wt %, wherein the concentrations in said range are substantially non-toxic to aquatic life.
2. A lubricant composition comprising:
(i) an ionic liquid having the following formula:
and
(ii) a polyalkylene glycol base lubricant;
wherein said ionic liquid is dissolved in said base lubricant and is included in said lubricant composition in a concentration in a range of 0.1-5 wt %, wherein the concentrations in said range are substantially non-toxic to aquatic life.
3. The lubricant composition of claim 1 , wherein said ionic liquid is included in said lubricant composition in an amount of 0.1-3 wt %.
4. The lubricant composition of claim 1 , wherein said ionic liquid is included in said lubricant composition in an amount of 0.1-2 wt %.
5. The lubricant composition of claim 1 , wherein said ionic liquid is included in said lubricant composition in an amount of 0.1-1 wt %.
6. The lubricant composition of claim 1 , wherein said base lubricant comprises a polyalkylene glycol.
7. The lubricant composition of claim 1 , wherein said base lubricant comprises a vegetable oil.
8. The lubricant composition of claim 1 , wherein said base lubricant comprises a synthetic ester oil.
9. The lubricant composition of claim 1 , wherein said base lubricant comprises a polyalphaolefin.
10. The lubricant composition of claim 1 , wherein said base lubricant comprises water.
11. The lubricant composition of claim 1 , wherein said ionic liquid is included in said lubricant composition in an amount of 0.5-5 wt %.