Lubricants and methods to determine dewetting thickness thereof

1. A lubricant comprising:

a plurality of segments, each linked together by ether linkages according to a general formula:

Re1-Rb1-Ri-Rc-Ri-Rb2-Re2;

wherein Rc is a divalent center segment including a perfluoroalkyl ether moiety;

wherein each of Rb1 and Rb2 is, independently, a sidechain segment including a perfluoroalkyl ether moiety;

wherein each Ri is, independently, a divalent linking segment including a functional group including elements from Group 13-17 of the periodic table of the elements;

wherein each of Re1 and Re2 is, independently, a monovalent end segment including a functional group including elements from Group 13-17 of the periodic table of the elements; wherein Rb1≠Rc≠Rb2; and

wherein the lubricant has a bonding percentage of about 70% to about 100% corresponding to a total area of a surface on which the lubricant is located.

2. The lubricant of claim 1 , wherein the bonding percentage is about 75% to about 100%, and an average thickness of a layer of the lubricant on the surface is about 0.3 nanometers to about 3 nanometers.

3. The lubricant of claim 1 , wherein the bonding percentage is about 80% to about 100%, and an average thickness of a layer of the lubricant on the surface is about 0.3 nanometers to about 3 nanometers.

4. The lubricant of claim 1 , wherein the bonding percentage is about 85% to about 100%, and an average thickness of a layer of the lubricant on the surface is about 0.3 nanometer to about 3 nanometers.

5. The lubricant of claim 1 , wherein the lubricant has a segment weight average molecular weight (α) determined according to the formula:

α=[molecular weight of Rb 1 +molecular weight of Rb 2 +molecular weight of Rc]÷3;

and

wherein a dewetting thickness of the lubricant, T dw , is determined according to the formula:

T dw =ψ (α);

wherein ψ is a function determined from a relationship between a dewetting thickness and a segment weight average molecular weight of a plurality of other lubricants;

wherein each of the plurality of other lubricants includes one or more segments including perfluoroalkyl ether moieties;

wherein the segment weight average molecular weight of each of the plurality of other lubricants is equal to a weight average molecular weight of the one or more segments including perfluoroalkyl ether moieties present in the respective other lubricant; and

wherein the segment weight average molecular weight of each of the plurality of other lubricants is about 300 grams/mole (g/mol) to about 5,000 g/mol.

6. The lubricant of claim 1 ,

wherein each functional group is —OH; or

wherein each functional group includes: a saturated C 1 -C 20 radical, an unsaturated C 1 -C 20 radical, an alicyclic C 3 -C 20 radical, a heterocyclic C 3 -C 20 radical, an aromatic C 5 -C 20 radical, a heteroaromatic C 5 -C 20 radical, a cyclotriphosphazine radical, a halogen, —NR 2 , —NR*—CO—R*,—OR*,—O—CO—R*, —CO—O—R*, —SeR*, —TeR*, —PR* 2 , —PO—(OR*) 2 , —O—PO—(OR*) 2 , —N═P(NR* 2 ) 3 , —AsR* 2 , —SR*, —SO 2 —(OR*) 2 , —SiR* 3 , —(CH 2 )q-SiR* 3 , —(CF 2 )q-SiR* 3 , or a combination thereof, wherein q is 1 to 10 and each R* is, independently, a hydrogen, a halogen, a saturated, unsaturated, aromatic, and/or heterocyclic C 1 -C 20 radical, and wherein two or more R* may join together to form a ring structure, and wherein at least one functional group is selected to be attachable to a protective overcoat of a magnetic recording media comprising the lubricant.

7. The lubricant of claim 1 , wherein a weight average molecular weight is from about 1 to about 20 kiloDaltons (kDa) and a polydispersity is about 1 to about 2.

8. The lubricant of claim 1 , wherein:

Rc includes a perfluoroethyl ether moiety;

each of Rb 1 and Rb 2 includes a perfluoroethyl ether moiety;

each Ri has the general formula:

Re 1 has the general formula:

and

Re 2 has the general formula:

wherein each R 1 is, independently, a functional group including elements from Group 13-17 of the periodic table of the elements, and

Rc is of the formula:

Rb 1 is of the formula:

and

Rb 2 is of the formula:

and

wherein each of x, y 1 and y 2 is, independently, an integer from 1 to 10.

9. The lubricant of claim 8 , wherein x is less than y 1 and x is less than y 2 ; or

wherein x is greater than y 1 and x is greater than y 2 .

10. The lubricant of claim 8 , wherein y 1 ≠y 2 .

11. The lubricant of claim 8 , wherein each R 1 is a hydroxyl (—OH).

12. The lubricant of claim 1 , having the formula:

wherein each of x, y 1 , and y 2 is an integer from 1 to 10; and

wherein y 1 ≠x≠y 2 .

13. The lubricant of claim 12 ,

wherein a dewetting thickness T dw =0.0045(α)+8.0226; and

wherein α=(116.015*y 1 +116.015*y 2 +116.015*x)÷3.

14. A data storage system, comprising:

at least one magnetic head;

a magnetic recording medium including a lubricant according to claim 1 ;

a drive mechanism for positioning the at least one magnetic head over the magnetic recording medium; and

a controller electrically coupled to the at least one magnetic head for controlling operation of the at least one magnetic head.

15. A data storage system, comprising:

a slider comprising at least one magnetic head and an air bearing surface, wherein a lubricant according to claim 1 is disposed on the air bearing surface; and

a magnetic recording medium including a magnetic recording layer;

wherein the slider is configured to write information to the magnetic recording layer using heat assisted magnetic recording.

16. The data storage system of claim 15 , wherein an average thickness of a layer of the lubricant on the surface is about 0.3 nanometers to about 3 nanometers.

17. A lubricant comprising a plurality of segments linked together by ether linkages according to a formula:

wherein each of x, y 1 , and y 2 is an integer from 1 to 10;

wherein y 1 ≠x≠y 2 ; and

wherein the lubricant has a bonding percentage of about 70% to less than about 100% corresponding to a total area of a surface on which the lubricant is located.

18. The lubricant of claim 17 , comprising a weight average molecular weight from about 1 to about 20 kiloDaltons (kDa) and a polydispersity from about 1 to about 2, and an average thickness of a layer of the lubricant on the surface is about 0.3 nanometers to about 3 nanometers.

19. A method to determine a dewetting thickness of a lubricant, comprising:

(a) generating a chemical representation of the lubricant including a plurality of segments, each linked together through an ether linkage according to a general formula:

Re 1 -Rb 1 -Ri-Rc-Ri-Rb 2 -Re 2 ;

wherein Rc is a divalent center segment including a perfluoroalkyl ether moiety;

wherein each of Rb 1 and Rb 2 is, independently, a sidechain segment including a perfluoroalkyl ether moiety;

wherein each Ri is, independently, a divalent linking segment including a functional group including elements from Group 13-17 of the periodic table of the elements;

wherein each of Re 1 and Re 2 is, independently, a monovalent end segment including a functional group including elements from Group 13-17 of the periodic table of the elements; and

wherein Rb 1 ≠Rc≠Rb 2 ;

wherein the lubricant has a bonding percentage of about 70% to about 100% corresponding to a total area of a surface on which the lubricant is located;

(b) determining a segment weight average molecular weight (α) according to the formula:

α=[molecular weight of Rb 1 +molecular weight of Rb 2 +molecular weight of Rc]÷3; and

(c) determining the dewetting thickness, T dw , of the lubricant according to the formula:

T dw =0.0045(α)+8.0226.

20. The method of claim 19 , wherein the lubricant comprises a compound with the formula:

wherein each of x, y 1 , and y 2 is an integer from 1 to 10;

wherein y 1 ≠x≠y 2 ;

wherein x is less than y 1 ;

wherein and x is less than y 2 ;

wherein y 1 ≠y 2 ; and

wherein α=(116.015*y 1 +116.015*y 2 +116.015*x)÷3.