Estolide compositions exhibiting high oxidative stability
Provided herein are estolide compositions having high oxidative stability, said compositions comprising at least one compound of formula: in which n is an integer equal to or greater than 0; m is an integer equal to or greater than 1; R 1 , independently for each occurrence, is selected from optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched; R 2 is selected from hydrogen and optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched; and R 3 and R 4 , independently for each occurrence, are selected from optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched. Also provided herein are uses for the compositions and methods of preparing the same.
1. A composition comprising an estolide base oil and an antioxidant, said composition having a time of at least 600 minutes when tested in a rotating pressurized vessel oxidation test using ASTM Method 2272-11,
wherein the composition has an acid value equal to or less than 0.5 mg KOH/g, and wherein the estolide base oil comprises at least one estolide compound selected from compounds of Formula I:
wherein
x is, independently for each occurrence, an integer selected from 0 to 20;
y is, independently for each occurrence, an integer selected from 0 to 20;
n is an integer greater than or equal to 0;
R 1 is an optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched; and
R 2 is an optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched,
wherein each fatty acid chain residue of said at least one estolide compound is independently optionally substituted.
2. The composition according to claim 1 , wherein
x is, independently for each occurrence, an integer selected from 1 to 10;
y is, independently for each occurrence, an integer selected from 1 to 10;
n is an integer selected from 0 to 8;
R 1 is an optionally substituted C 1 to C 22 alkyl that is saturated or unsaturated, and branched or unbranched; and
R 2 is an optionally substituted C 1 to C 22 alkyl that is saturated or unsaturated, and branched or unbranched,
wherein each fatty acid chain residue is unsubstituted.
3. The composition according to claim 2 , wherein
x+y is, independently for each chain, an integer selected from 13 to 15; and
n is an integer selected from 0 to 6.
4. The composition according to claim 1 , wherein R 2 is an unsubstituted alkyl that is saturated or unsaturated, and branched or unbranched.
5. The composition according to claim 4 , wherein R 2 is a branched C 1 to C 20 alkyl that is saturated.
6. The composition according to claim 5 , wherein R 2 is a C 6 to C 12 alkyl.
7. The composition according to claim 1 , wherein R 1 is an unbranched C 1 to C 20 alkyl that is unsubstituted and saturated or unsaturated.
8. The composition according to claim 7 , wherein R 1 is saturated.
9. The composition according to claim 1 , wherein said composition has a time of at least 700 minutes when tested in a rotating pressurized vessel oxidation test using ASTM Method 2272-11.
10. The composition according to claim 1 , wherein the antioxidant comprises at least one diarylamine antioxidant.
11. The composition according to claim 10 , wherein the antioxidant comprises at least one diphenylamine antioxidant.
12. The composition according to claim 11 , wherein the antioxidant comprises at least one alkylated diphenylamine antioxidant.
13. The composition according to claim 12 , wherein the antioxidant comprises at least one nonylated diphenylamine, octylated diphenylamine, or butylated diphenylamine.
14. The composition according to claim 1 , wherein the antioxidant comprises at least one amine antioxidant.
15. The composition according to claim 1 , wherein the composition has an acid value of equal to or less than 0.1 mg KOH/g.
16. The composition according claim 1 , wherein the composition is substantially free of fatty acids.
17. The composition according to claim 3 , wherein x is, independently for each occurrence, an integer selected from 7 and 8.
18. The composition according to claim 3 , wherein y is, independently for each occurrence, an integer selected from 7 and 8.
19. The composition according to claim 3 , wherein R 2 is unsubstituted.
20. The composition according to claim 3 , wherein R 2 is unsubstituted and saturated.
21. The composition according to claim 20 , wherein R 2 is selected from a branched C 6 to C 12 alkyl.
22. The composition according to claim 3 , wherein R 1 is unsubstituted.
23. The composition according to claim 20 , wherein R 1 is unsubstituted and saturated.
24. The composition according to claim 23 , wherein R 1 is unbranched.
25. The composition according to claim 14 , wherein the antioxidant further comprises at least one phenolic antioxidant.
26. The composition according to claim 25 , wherein the antioxidant comprises at least one diarylamine antioxidant and at least one hindered phenolic antioxidant.
27. The composition according to claim 25 , wherein the antioxidant comprises 0.01 to 5 wt % of the composition.
28. The composition according to claim 1 , wherein the composition further comprises at least one lubricating oil selected from one or more of a Group I oil, a Group II oil, a Group III oil, a polyalphaolefin, a polyalkylene glycol, or an oil soluble polyalkylene glycol.
29. The composition according to claim 28 , wherein the at least one lubricating oil comprises an oil soluble polyalkylene glycol.
30. The composition according to claim 1 , further comprising at least one additive comprising one or more of an antimicrobial agent, an extreme pressure agent, a cold flow modifier, a friction modifier, a viscosity modifier, a pour point depressant, a metal chelating agent, a metal deactivator, an antifoaming agent, or a demulsifier.
31. The composition according to claim 30 , wherein the at least one additive comprises an extreme pressure agent.
32. The composition according to claim 31 , wherein the at least one additive comprises a phosphorous extreme pressure agent.
33. The composition according to claim 30 , wherein the at least one additive comprises a metal deactivator.
34. The composition according to claim 30 , wherein the at least one additive comprises a demulsifier.
35. The composition according to claim 31 , wherein R 2 is an unsubstituted C 1 to C 20 alkyl that is saturated.
36. The composition according to claim 35 , wherein R 2 is branched.
37. The composition according to claim 35 , wherein R 1 is an unsubstituted C 1 to C 20 alkyl that is unbranched.
38. The composition according to claim 37 , wherein R 1 is saturated.
39. The composition according to claim 38 , wherein x is, independently for each occurrence, an integer selected from 7 and 8.
40. The composition according to claim 39 , wherein y is, independently for each occurrence, an integer selected from 7 and 8.
41. The composition according to claim 40 , further comprising a metal deactivator.
42. The composition according to claim 41 , further comprising a demulsifier.