Lubricant compositions, and synthesizing methods and applications of same
A lubricant composition includes a base lubricant and a plurality of lubricant additive molecules functioning as precursor molecules to induce tribopolymerization and forming in situ protective tribofilm with desirable robustness and low shear resistance. Each lubricant additive molecule includes one or more surface-active groups attractable to target surface, and a carbon containing component operable connected to the one or more surface active groups. The carbon containing component comprise a carbon ring structure having a high ring strain that is metastable and activatable with a ring-opening reaction. A less stable carbon ring structure is more readily activated to the intermediate state, preferable to form more active fragments. Increasing the adsorption strength further is beneficial to prolonging the residence time of additive molecules on the target surface, thereby facilitating the dissociation of molecules and subsequent polymerization.
1. A lubricant additive, comprising:
one or more surface-active groups attractable to a target surface; and
a carbon containing component operable connected to the one or more surface active groups, wherein the carbon containing component comprises a carbon ring structure having a high ring strain that is metastable and activatable with a ring-opening reaction,
wherein the one or more surface active groups comprise two or more carboxyl groups;
wherein the lubricant additive comprises cycloalkane-carboxylic acid molecules, wherein the cycloalkane-carboxylic acid molecules comprise cyclopropanecarboxylic acid (CPCa), cyclobutanecarboxylic acid (CBCa), cyclopropane-1,1-dicarboxylic acid (CPDCa), and cyclobutane-1,1-dicarboxylic acid (CBDCa), or a mixture thereof; and
wherein a carbon film is operably formed in situ on the target surface only when tribological energy activates the lubricant additive to unravel the carbon containing component under a pressure and a temperature during operation.
2. The lubricant additive of claim 1 , wherein the lubricant additive has a higher adsorption strength to allow molecules to remain on the target surface long enough to facilitate dissociation induced mechanically or thermally and subsequent polymerization to yield tribopolymers.
3. The lubricant additive of claim 1 , wherein the lubricant additive operably binds to the target surface via polar (electrostatic) or chemical interactions through the surface active group.
4. The lubricant additive of claim 1 , wherein increasing the number of the carboxyl groups results in stronger binding of the lubricant additive to the target surface, thereby increasing residence time and hence facilitating mechanically or thermally induced dissociation and subsequent polymerization.
5. A lubricant composition used for in situ forming a carbon film on a target surface of a target machine, comprising:
a base lubricant; and
a plurality of lubricant additive molecules, wherein each lubricant additive molecule comprises:
one or more surface-active groups attractable to a target surface; and
a carbon containing component operable connected to the one or more surface active groups, wherein the carbon containing component comprise a carbon ring structure having a high ring strain that is metastable and activatable with a ring-opening reaction,
wherein the one or more surface active groups comprise two or more carboxyl groups;
wherein the plurality of lubricant additive molecules comprises cycloalkane-carboxylic acid molecules, wherein the cycloalkane-carboxylic acid molecules comprises cyclopropanecarboxylic acid (CPCa), cyclobutanecarboxylic acid (CBCa), cyclopropane-1,1-dicarboxylic acid (CPDCa), and cyclobutane-1,1-dicarboxylic acid (CBDCa), or a mixture thereof; and
wherein the carbon film is formed on the target surface of the target machine only when tribological energy activates the lubricant additive to unravel the carbon containing component under a pressure and a temperature during operation.
6. The lubricant composition of claim 5 , wherein the lubricant composition has about 0.5-10 wt. % of the lubricant additive molecules.
7. The lubricant composition of claim 6 , wherein the lubricant composition has about 0.5 wt. % of the lubricant additive molecules.
8. The lubricant composition of claim 5 , wherein the carbon film is oligomeric/polymeric in nature.
9. The lubricant composition of claim 5 , wherein the lubricant additive has a higher adsorption strength to allow molecules to remain on the target surface long enough to facilitate dissociation induced mechanically or thermally and subsequent polymerization to yield tribopolymers.
10. The lubricant composition of claim 5 , wherein the lubricant additive molecules operably bind to the target surface via polar (electrostatic) or chemical interactions through the one or more surface active groups.
11. The lubricant composition of claim 10 , wherein the one or more surface active groups have positive charges, and the target surface has negative charges, and vice versa, such that the one or more surface active groups are attractable to the target surface.
12. The lubricant composition of claim 5 , wherein the lubricant composition has Raman features at about 1350 and 1580 cm −1 .
13. A method for in situ forming a carbon film on a target surface of a target machine, comprising:
adding the lubricant composition of claim 5 into the target machine, wherein the lubricant composition is in contact with the target surface of the target machine; and
operating the target machine to cause a temperature and a pressure at the target surface so that the carbon containing component is unraveled thereon to form a carbon film on the target surface during the operation.
14. The method of claim 13 , wherein the lubricant composition has about 0.5-10 wt. % of the lubricant additive molecules.
15. The method of claim 13 , wherein the temperature is in a range of 25° C.-500° C., and the pressure is in a range of 0.1-3 Gpa.
16. The method of claim 13 , wherein the carbon film is oligomeric/polymeric in nature.