Novel carbon dot composite lubricating oil gelator as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of lubricating oil gels, and discloses a novel carbon dot composite lubricating oil gelator as well as a preparation method and application thereof. The preparation method comprises the following steps: dissolving 1-boric acid furan and 2-aminothiophenol in methanol, adding sodium hydroxide, carrying out ultrasonic dispersion, carrying out solvent heat treatment at 210 DEG C after ultrasonic dispersion, and carrying out alumina column chromatography to obtain carbon dots; the preparation method comprises the following steps: synthesizing a fluorine-containing gelator with a maleic amide ring as a terminal group through esterification reaction, adding carbon dots and the gelator into base oil, heating and dissolving, and cooling at room temperature to obtain gel-state carbon dot-based composite lubricating oil gel; the compound lubricating oil gelator is prepared by screening a precursor structure and designing, the strength improvement and reversible thermal conversion of gel fibers can be realized through [4 + 2] addition reaction, the compound lubricating oil gelator is applicable to III, IV and V lubricating oil and shows high antiwear and antifriction properties, and the prepared compound lubricating oil gel can keep the stability for more than one year.

Description

Technical Field

[0001] The present invention belongs to the technical field of lubricating oil gels, and in particular relates to a novel carbon dot composite lubricating oil gel factor, a preparation method and an application thereof. Background Art

[0002] In large-scale machinery, transportation, and other sectors, energy losses due to friction and wear account for approximately 30% of global energy consumption. Friction and wear not only accelerate material failure, but also significantly increase energy consumption and impact system stability. Introducing lubricants into material interfaces is the most direct and effective means of reducing friction and wear and extending component life. Lubrication plays a key role in improving the service life and operational efficiency of mechanical systems. However, conventional base oils are susceptible to sludge, carbon deposits, and varnish formation under high temperature, high pressure, or prolonged operation, severely impacting lubrication performance and equipment stability. Therefore, the development of novel lubricating materials with self-cleaning capabilities that can maintain lubrication system cleanliness over time and provide efficient and stable lubrication performance even in demanding environments has become a key research direction in the lubrication field. Nanomaterials, such as metal nanoparticles, carbon-based nanomaterials, and covalent organic frameworks (COFs), demonstrate promising potential as lubricant additives due to their size effects and excellent physicochemical properties. They effectively enhance the friction and anti-wear properties of lubricants through multiple mechanisms, including rolling friction, film formation, surface polishing, and repair of worn areas.

[0003] Carbon dots, a zero-dimensional carbon nanomaterial, were first reported in 2004, with a particle size typically less than 10 nm. They have a wide range of raw material sources, low preparation costs, and good water solubility, fluorescence properties, chemical stability, and environmental friendliness. Recent studies have shown that carbon dots can significantly improve the friction-reducing and anti-wear properties of lubricants through multiple mechanisms, such as rolling friction, forming a protective film at the friction interface, and filling surface depressions, and have the potential to become an efficient lubricant additive. However, carbon dots themselves have a strong polarity, resulting in poor dispersion stability in current mainstream non-polar commercial lubricants, making it difficult to achieve long-term uniform distribution. This dispersion barrier severely limits the practical application and commercial value of carbon dots in industrial lubrication systems. Summary of the Invention

[0004] The present invention aims to address the limitations of industrial applications caused by the poor dispersion stability of carbon dots in currently mainstream non-polar commercial lubricants. By providing a novel carbon dot composite lubricant gelling agent, its preparation method, and its application, the preparation method utilizes readily available raw materials, offers low synthesis costs, is simple to operate, and has a wide range of applications. The novel carbon dot composite lubricant gelling agent prepared using the present invention exhibits excellent gelling properties in Class III, IV, and V lubricants. The resulting gel fiber network exhibits excellent stability and reversible shear and temperature responsiveness, further enhancing the lubricant's load-bearing capacity and anti-wear and friction-reducing properties.

[0005] In order to achieve the above objectives, the technical solutions adopted in this application are: The first object of the present invention is to provide a method for preparing a novel carbon dot composite lubricating oil gel factor, comprising the following steps: S1. Dissolve maleimide undecanoic acid, 2H-perfluoro-1-decanol, 1,3-dicyclohexylcarbodiimide and a catalyst in dichloromethane, stir at room temperature for 24 hours, and obtain a fluorinated gel factor by silica gel column chromatography in an eluent; S2, dissolving 1-furan borate and 2-aminothiophenol in methanol, adding sodium hydroxide and ultrasonically dispersing, then performing solvothermal treatment, and then performing alumina column chromatography in ethanol to obtain carbon dots; S3. Add a certain proportion of fluorine-containing gel factor and carbon dots into methanol, reflux with stirring, and remove the solvent under reduced pressure to obtain a novel carbon dot composite lubricating oil gel factor.

[0006] Preferably, the molar mass ratio of maleimide undecanoic acid, 2H-perfluoro-1-decanol, 1,3-dicyclohexylcarbodiimide and catalyst in S1 is 1:1.1:1.1:(0.01-0.05); the volume of dichloromethane is 10-20 mL; The catalyst is one of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 4-dimethylaminopyridine.

[0007] Preferably, the rotation speed during the stirring process in S1 is 300~600rpm, the desolvant is a mixed solvent of methanol and dichloromethane, the volume ratio of methanol to dichloromethane is 1:20; the silica gel particle size in the silica gel column chromatography is 100~300 mesh.

[0008] Preferably, the mass ratio of the 1-boric acid furan to the sodium hydroxide in S2 is 1:(0.5-1.5), and the volume of the 2-aminothiophenol is 160-220 μL.

[0009] Preferably, the ultrasonic dispersion in S2 is performed for 10 to 15 minutes; the solvent thermal treatment is performed at a temperature of 200° C. to 220° C. for 3 to 5 hours.

[0010] Preferably, the ratio of the fluorine-containing gel factor to the carbon dots in S3 is (5-10):1.

[0011] Preferably, the reflux stirring temperature is 60-80° C., and the stirring time is 2-3 h.

[0012] The second object of the present invention is to provide a novel carbon dot composite lubricating oil gel factor prepared by the above preparation method.

[0013] The third object of the present invention is to provide the use of the novel carbon dot composite lubricant gel factor in lubricating oil, wherein the novel carbon dot composite lubricant gel factor is dispersed in lubricating oil at 60-90°C and cooled to room temperature.

[0014] Preferably, the amount of the novel carbon dot composite lubricant gel factor added to the lubricant is 1 to 6 wt %; the lubricant is one of Class III lubricant, Class IV lubricant, and Class V lubricant.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention designs the structure and gel fiber morphology of the carbon dot composite lubricant gel factor, which can make it exhibit excellent compatibility, gelation, and higher anti-wear and friction-reducing properties in various lubricants. The raw materials used in the preparation method are easy to obtain, the synthesis cost is low, the operation method is simple, and the application range is wide. The three-dimensional gel network formed by the new carbon dot composite lubricant gel factor prepared by the preparation method of the present invention has good structural stability, can maintain good lubrication performance for more than one year, and has extremely long lubrication time.

[0016] (2) The results show that compared with pure PAO, 500SN, and ANs lubricants, the addition of the new carbon dot composite lubricant gel factor designed by the present invention to the lubricant at a concentration of only 1 wt% can reduce the average friction coefficient from 0.155, 0.150, and 0.153 to 0.108, 0.107, and 0.101; the wear volume is reduced by 48%, 58%, and 74%, respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 These are SEM morphologies of the gel factor of the novel carbon dot composite lubricant prepared in Examples 1-3 of the present invention, where (a) is a panoramic view and (b) is an enlarged view of the center point; Figure 2Friction coefficient curves and wear volume histograms of the novel carbon dot composite lubricant gel factor prepared in Examples 1-3 of the present invention added to PAO, 500SN, and ANs lubricants, respectively. (a) is a friction coefficient curve of the novel carbon dot composite lubricant gel factor added to PAO; (b) is a friction coefficient curve of the novel carbon dot composite lubricant gel factor added to 500SN; (c) is a friction coefficient curve of the novel carbon dot composite lubricant gel factor added to ANs; (d) is a wear volume histogram; Figure 3 This is a comparison chart of the dispersion stability of the new carbon dot composite lubricant gel factors prepared in Examples 1-9 of the present invention in PEG, PAO, 500SN, ANs, PIPE, POE, 1936, 3970, and A51, respectively. DETAILED DESCRIPTION

[0018] The following will be combined with the data in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0020] The present invention provides a method for preparing a novel carbon dot composite lubricating oil gel factor, comprising the following steps: S1. Maleamide undecanoic acid, 2H-perfluoro-1-decanol, 1,3-dicyclohexylcarbodiimide and a catalyst are dissolved in 10-20 mL of dichloromethane in a molar mass ratio of 1:1.1:1.1:(0.01-0.05), for example, 1:1.1:1.1:0.01, 1:1.1:1.1:0.02, 1:1.1:1.1:0.03, 1:1.1:1.1:0.04, or 1:1.1:1.1:0.05. The mixture is stirred at room temperature at a speed of 300-600 rpm for 24 h, and the fluorinated gel factor is obtained after silica gel column chromatography in a desolvant; In some embodiments of the present invention, the catalyst is one of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 4-dimethylaminopyridine; the eluent is a mixed solvent of methanol and dichloromethane, and the volume ratio of methanol to dichloromethane is 1:20; the silica gel particle size in the silica gel column chromatography is 100-300 mesh; S2. Dissolve 1-furan borate and 2-aminothiophenol in methanol, add sodium hydroxide, and ultrasonically disperse for 10 to 15 minutes, for example, 10 minutes, 12 minutes, 14 minutes, and 15 minutes. Solvothermal treatment is performed at 200° C. to 220° C. for 3 to 5 hours, for example, 3 hours, 4 hours, and 5 hours. Then, the carbon dots are obtained by chromatography on an alumina column in ethanol. The mass ratio of 1-furan borate to sodium hydroxide is 1: (0.5-1.5), for example, 1:0.5, 1:0.7, 1:0.9, 1:1.2, 1:1.5; the volume of dissolved 2-aminothiophenol is 160 to 220 μL, for example, 160 μL, 170 μL, 180 μL, 190 μL, 200 μL, 210 μL, 220 μL; S3. Add the fluorinated gel factor and carbon dots to methanol in any ratio of (5-10):1, for example, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1, and reflux with stirring at 60-80°C for 2-3 hours. Remove the solvent under reduced pressure to obtain a novel carbon dot composite lubricating oil gel factor.

[0021] The present invention designs the structure and gel fiber morphology of the carbon dot composite lubricant gel factor, so that it can exhibit excellent compatibility, gelation, and higher anti-wear and friction-reducing properties in various lubricants. The raw materials used in the preparation method are easily available, the synthesis cost is low, the operation method is simple, and the application range is wide. The three-dimensional gel network formed by the novel carbon dot composite lubricant gel factor prepared by the preparation method of the present invention has good structural stability, can maintain good lubrication performance for more than one year, and has extremely long lubrication timeliness.

[0022] The present invention also provides an application of a novel carbon dot composite lubricant gel factor in lubricating oil, wherein the novel carbon dot composite lubricant gel factor is dispersed in lubricating oil at 60 to 90°C, for example, 60°C, 70°C, 80°C, or 90°C, and cooled to room temperature; wherein the novel carbon dot composite lubricant gel factor is added to the lubricating oil in an amount of 1 to 6 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or 6 wt%.

[0023] In some embodiments of the present invention, the lubricant is one of Group III lubricant, Group IV lubricant, and Group V lubricant, specifically PEG, PAO, 500SN, ANs, PIPE, POE, 1936, 3970, A51, etc. Compared with pure PAO, 500SN, and ANs lubricants, the lubricant with the addition of the new carbon dot composite lubricant gel factor can reduce the average friction coefficient from 0.155, 0.150, and 0.153 to 0.108, 0.107, and 0.101 at a concentration of only 1 wt%; the wear volume is reduced by 48%, 58%, and 74%, respectively.

[0024] The following is further described through specific examples.

[0025] Example 1 A method for preparing a novel carbon dot composite lubricating oil gel comprises the following steps: S1. Dissolve 10 mmol of maleimide undecanoic acid, 11 mmol of 2H-perfluoro-1-decanol, 11 mmol of 1,3-dicyclohexylcarbodiimide and 0.5 mmol of 4-dimethylaminopyridine in 20 mL of dichloromethane.

[0026] The mixture was stirred at 300 rpm at room temperature for 24 h and purified by 200-mesh silica gel column chromatography using a mixed solvent of methanol:dichloromethane = 1:20 as eluent to obtain a fluorinated gelling factor named Gel.

[0027] S2. Dissolve 0.2 g of 1-boronic acid furan and 162 μL of 2-aminothiophenol in 15 mL of methanol. Add 0.1 g of sodium hydroxide and disperse by ultrasonication. Solvothermal treatment is performed at 210°C for 3 h. Carbon dots (CDs) are obtained after chromatography on a neutral alumina column using ethanol as the eluent.

[0028] S3. Dissolve 1 g of Gel and 0.2 g of CDs in 20 mL of methanol, reflux with stirring at 80°C for 3 hours, and remove the solvent under reduced pressure to obtain a carbon dot composite gel factor, named Gel@CDs-0.2.

[0029] S4. 50 mg of Gel@CDs-0.2 was dispersed in 950 mg of PAO oil at 80°C. After cooling, the oil was tested using an SRV5 fretting friction and wear tester at 150°C, an amplitude of 1 mm, and a frequency of 25 Hz. Compared with pure PAO oil, the friction coefficient of the carbon dot composite lubricant gel decreased from 0.155 to 0.108, and the wear spot volume was reduced by 48%.

[0030] Example 2 A method for preparing a novel carbon dot composite lubricating oil gel comprises the following steps: S1. Dissolve 10 mmol of maleimide undecanoic acid, 11 mmol of 2H-perfluoro-1-decanol, 11 mmol of 1,3-dicyclohexylcarbodiimide and 0.5 mmol of 4-dimethylaminopyridine in 20 mL of dichloromethane.

[0031] The mixture was stirred at 300 rpm at room temperature for 24 h and purified by 200-mesh silica gel column chromatography using a mixed solvent of methanol:dichloromethane = 1:20 as eluent to obtain a fluorinated gelling factor named Gel.

[0032] S2. Dissolve 0.2 g of 1-boronic acid furan and 162 μL of 2-aminothiophenol in 15 mL of methanol. Add 0.1 g of sodium hydroxide and disperse by ultrasonication. Solvothermal treatment is performed at 210°C for 3 h. Carbon dots (CDs) are obtained after chromatography on a neutral alumina column using ethanol as the eluent.

[0033] S3. Dissolve 1 g of Gel and 0.2 g of CDs in 20 mL of methanol, reflux and stir at 80°C for 3 hours, and remove the solvent under reduced pressure to obtain a carbon dot composite gel factor, named Gel@CDs-0.2.

[0034] S4: 50 mg of Gel@CDs-0.2 was dispersed in 950 mg of 500SN oil at 80°C. After cooling, the mixture was tested using an SRV5 fretting tribometer at 150°C, an amplitude of 1 mm, and a frequency of 25 Hz. Compared to pure 500SN oil, the friction coefficient of the carbon dot composite lubricant gel decreased from 0.150 to 0.107, and the wear spot volume was reduced by 58%.

[0035] Example 3 A method for preparing a novel carbon dot composite lubricating oil gel comprises the following steps: S1. Dissolve 10 mmol of maleimide undecanoic acid, 11 mmol of 2H-perfluoro-1-decanol, 11 mmol of 1,3-dicyclohexylcarbodiimide and 0.5 mmol of 4-dimethylaminopyridine in 20 mL of dichloromethane.

[0036] The mixture was stirred at 300 rpm at room temperature for 24 h and purified by 200-mesh silica gel column chromatography using a mixed solvent of methanol:dichloromethane = 1:20 as eluent to obtain a fluorinated gelling factor named Gel.

[0037] S2. Dissolve 0.2 g of 1-boronic acid furan and 162 μL of 2-aminothiophenol in 15 mL of methanol. Add 0.1 g of sodium hydroxide and disperse by ultrasonication. Solvothermal treatment is performed at 210°C for 3 h. Carbon dots (CDs) are obtained after chromatography on a neutral alumina column using ethanol as the eluent.

[0038] S3. Dissolve 1 g of Gel and 0.2 g of CDs in 20 mL of methanol, reflux and stir at 80°C for 3 hours, and remove the solvent under reduced pressure to obtain a carbon dot composite gel factor, named Gel@CDs-0.2.

[0039] S4. 50 mg of Gel@CDs-0.2 was dispersed in 950 mg of ANs oil at 80°C. After cooling, the material was tested using an SRV5 fretting friction and wear tester at 150°C, an amplitude of 1 mm, and a frequency of 25 Hz. Compared with pure ANs oil, the friction coefficient of the carbon dot composite lubricant gel decreased from 0.153 to 0.101, and the wear spot volume was reduced by 78%.

[0040] Example 4 A method for preparing a novel carbon dot composite lubricating oil gel comprises the following steps: S1. Dissolve 10 mmol of maleimide undecanoic acid, 11 mmol of 2H-perfluoro-1-decanol, 11 mmol of 1,3-dicyclohexylcarbodiimide and 0.5 mmol of 4-dimethylaminopyridine in 20 mL of dichloromethane.

[0041] The mixture was stirred at 300 rpm at room temperature for 24 h and purified by 200-mesh silica gel column chromatography using a mixed solvent of methanol:dichloromethane = 1:20 as eluent to obtain a fluorinated gelling factor named Gel.

[0042] S2. Dissolve 0.2 g of 1-boronic acid furan and 162 μL of 2-aminothiophenol in 15 mL of methanol. Add 0.1 g of sodium hydroxide and disperse by ultrasonication. Solvothermal treatment is performed at 210°C for 3 h. Carbon dots (CDs) are obtained after chromatography on a neutral alumina column using ethanol as the eluent.

[0043] S3. Dissolve 1 g of Gel and 0.18 g of CDs in 20 mL of methanol, reflux and stir at 80°C for 3 hours, and remove the solvent under reduced pressure to obtain a carbon dot composite gel factor, named Gel@CDs-0.18.

[0044] S4. 50 mg of Gel@CDs-0.18 was dispersed in 950 mg of POE oil at 80°C. After cooling, the mixture was tested using an SRV5 fretting friction and wear tester at 150°C, an amplitude of 1 mm, and a frequency of 25 Hz. Compared with pure POE oil, the friction coefficient of the carbon dot composite lubricant gel decreased from 0.145 to 0.106, and the wear spot volume was reduced by 52%.

[0045] Example 5 A method for preparing a novel carbon dot composite lubricating oil gel comprises the following steps: S1. Dissolve 10 mmol of maleimide undecanoic acid, 11 mmol of 2H-perfluoro-1-decanol, 11 mmol of 1,3-dicyclohexylcarbodiimide and 0.5 mmol of 4-dimethylaminopyridine in 20 mL of dichloromethane.

[0046] The mixture was stirred at 300 rpm at room temperature for 24 h and purified by 200-mesh silica gel column chromatography using a mixed solvent of methanol:dichloromethane = 1:20 as eluent to obtain a fluorinated gelling factor named Gel.

[0047] S2. Dissolve 0.2 g of 1-boronic acid furan and 162 μL of 2-aminothiophenol in 15 mL of methanol. Add 0.1 g of sodium hydroxide and disperse by ultrasonication. Solvothermal treatment is performed at 210°C for 3 h. Carbon dots (CDs) are obtained after chromatography on a neutral alumina column using ethanol as the eluent.

[0048] S3. Dissolve 1 g of Gel and 0.18 g of CDs in 20 mL of methanol, reflux and stir at 80°C for 3 hours, and remove the solvent under reduced pressure to obtain a carbon dot composite gel factor, named Gel@CDs-0.18.

[0049] S4. 50 mg of Gel@CDs-0.18 was dispersed in 950 mg of PIPE oil at 80°C. After cooling, the material was tested using an SRV5 fretting friction and wear tester at 150°C, an amplitude of 1 mm, and a frequency of 25 Hz. Compared with pure PIPE oil, the friction coefficient of the carbon dot composite lubricant gel decreased from 0.159 to 0.113, and the wear spot volume was reduced by 37%.

[0050] Example 6 A method for preparing a novel carbon dot composite lubricating oil gel comprises the following steps: S1. Dissolve 10 mmol of maleimide undecanoic acid, 11 mmol of 2H-perfluoro-1-decanol, 11 mmol of 1,3-dicyclohexylcarbodiimide and 0.5 mmol of 4-dimethylaminopyridine in 20 mL of dichloromethane.

[0051] The mixture was stirred at 300 rpm at room temperature for 24 h and purified by 200-mesh silica gel column chromatography using a mixed solvent of methanol:dichloromethane = 1:20 as eluent to obtain a fluorinated gelling factor named Gel.

[0052] S2. Dissolve 0.2 g of 1-boronic acid furan and 162 μL of 2-aminothiophenol in 15 mL of methanol. Add 0.1 g of sodium hydroxide and disperse by ultrasonication. Solvothermal treatment is performed at 210°C for 3 h. Carbon dots (CDs) are obtained after chromatography on a neutral alumina column using ethanol as the eluent.

[0053] S3. Dissolve 1 g of Gel and 0.15 g of CDs in 20 mL of methanol, reflux and stir at 80°C for 3 hours, and remove the solvent under reduced pressure to obtain a carbon dot composite gel factor, named Gel@CDs-0.15.

[0054] S4. 50 mg of Gel@CDs-0.15 was dispersed in 950 mg of 1936 oil at 80°C. After cooling, the oil was tested using an SRV5 fretting tribometer at 150°C, an amplitude of 1 mm, and a frequency of 25 Hz. Compared to pure 1936 oil, the friction coefficient of the carbon dot composite lubricant gel decreased from 0.144 to 0.115, and the wear spot volume was reduced by 45%.

[0055] Example 7 A method for preparing a novel carbon dot composite lubricating oil gel comprises the following steps: S1. Dissolve 10 mmol of maleimide undecanoic acid, 11 mmol of 2H-perfluoro-1-decanol, 11 mmol of 1,3-dicyclohexylcarbodiimide and 0.5 mmol of 4-dimethylaminopyridine in 20 mL of dichloromethane.

[0056] The mixture was stirred at 300 rpm at room temperature for 24 h and purified by 200-mesh silica gel column chromatography using a mixed solvent of methanol:dichloromethane = 1:20 as eluent to obtain a fluorinated gelling factor named Gel.

[0057] S2. Dissolve 0.2 g of 1-boronic acid furan and 162 μL of 2-aminothiophenol in 15 mL of methanol. Add 0.1 g of sodium hydroxide and disperse by ultrasonication. Solvothermal treatment is performed at 210°C for 3 h. Carbon dots (CDs) are obtained after chromatography on a neutral alumina column using ethanol as the eluent.

[0058] S3. Dissolve 1 g of Gel and 0.15 g of CDs in 20 mL of methanol, reflux and stir at 80°C for 3 hours, and remove the solvent under reduced pressure to obtain a carbon dot composite gel factor, named Gel@CDs-0.15.

[0059] S4. 50 mg of Gel@CDs-0.15 was dispersed in 950 mg of 3970 oil at 80°C. After cooling, the material was tested using an SRV5 fretting tribometer at 150°C, an amplitude of 1 mm, and a frequency of 25 Hz. Compared to neat 3970 oil, the friction coefficient of the carbon dot composite lubricant gel decreased from 0.146 to 0.125, and the wear spot volume was reduced by 31%.

[0060] Example 8 A method for preparing a novel carbon dot composite lubricating oil gel comprises the following steps: S1. Dissolve 10 mmol of maleimide undecanoic acid, 11 mmol of 2H-perfluoro-1-decanol, 11 mmol of 1,3-dicyclohexylcarbodiimide and 0.5 mmol of 4-dimethylaminopyridine in 20 mL of dichloromethane.

[0061] The mixture was stirred at 300 rpm at room temperature for 24 h and purified by 200-mesh silica gel column chromatography using a mixed solvent of methanol:dichloromethane = 1:20 as eluent to obtain a fluorinated gelling factor named Gel.

[0062] S2. Dissolve 0.2 g of 1-boronic acid furan and 162 μL of 2-aminothiophenol in 15 mL of methanol. Add 0.1 g of sodium hydroxide and disperse by ultrasonication. Solvothermal treatment is performed at 210°C for 3 h. Carbon dots (CDs) are obtained after chromatography on a neutral alumina column using ethanol as the eluent.

[0063] S3. Dissolve 1 g of Gel and 0.125 g of CDs in 20 mL of methanol, reflux and stir at 80°C for 3 hours, and remove the solvent under reduced pressure to obtain a carbon dot composite gel factor, named Gel@CDs-0.125.

[0064] S4. 50 mg of Gel@CDs-0.125 was dispersed in 950 mg of A51 oil at 80°C. After cooling, the oil was tested using an SRV5 fretting tribometer at 150°C, an amplitude of 1 mm, and a frequency of 25 Hz. Compared to pure A51 oil, the friction coefficient of the carbon dot composite lubricant gel decreased from 0.136 to 0.105, and the wear spot volume was reduced by 59%.

[0065] Example 9 A method for preparing a novel carbon dot composite lubricating oil gel comprises the following steps: S1. Dissolve 10 mmol of maleimide undecanoic acid, 11 mmol of 2H-perfluoro-1-decanol, 11 mmol of 1,3-dicyclohexylcarbodiimide and 0.5 mmol of 4-dimethylaminopyridine in 20 mL of dichloromethane.

[0066] The mixture was stirred at 300 rpm at room temperature for 24 h and purified by 200-mesh silica gel column chromatography using a mixed solvent of methanol:dichloromethane = 1:20 as eluent to obtain a fluorinated gelling factor named Gel.

[0067] S2. Dissolve 0.2 g of 1-boronic acid furan and 162 μL of 2-aminothiophenol in 15 mL of methanol. Add 0.1 g of sodium hydroxide and disperse by ultrasonication. Solvothermal treatment is performed at 210°C for 3 h. Carbon dots (CDs) are obtained after chromatography on a neutral alumina column using ethanol as the eluent.

[0068] S3. Dissolve 1 g of Gel and 0.1 g of CDs in 20 mL of methanol, reflux with stirring at 80°C for 3 h, and remove the solvent under reduced pressure to obtain a carbon dot composite gel factor, named Gel@CDs-0.1.

[0069] S4. 50 mg of Gel@CDs-0.1 was dispersed in 950 mg of PEG oil at 80°C. After cooling, the material was tested using an SRV5 fretting friction and wear tester at 150°C, an amplitude of 1 mm, and a frequency of 25 Hz. Compared with pure PEG oil, the friction coefficient of the carbon dot composite lubricant gel decreased from 0.189 to 0.123, and the wear spot volume was reduced by 38%.

[0070] Comparative Example 1 A method for preparing a fluorine-containing lubricating oil gel comprises the following steps: S1. Dissolve 10 mmol of maleimide undecanoic acid, 11 mmol of 2H-perfluoro-1-decanol, 11 mmol of 1,3-dicyclohexylcarbodiimide and 0.5 mmol of 4-dimethylaminopyridine in 20 mL of dichloromethane.

[0071] The product was stirred at 300 rpm for 24 h at room temperature and purified by 200-mesh silica gel column chromatography using a mixed solvent of methanol: dichloromethane = 1:20 as the eluent, and named Gel.

[0072] S4: 50 mg of the gel was dispersed in 950 mg of PAO oil at 80°C. After cooling, the gel was tested using an SRV5 fretting friction and wear tester at 150°C, an amplitude of 1 mm, and a frequency of 25 Hz. Compared with pure PEG oil, the friction coefficient of the carbon dot composite lubricant gel decreased from 0.155 to 0.113, and the wear spot volume was reduced by 28%.

[0073] Comparative Example 2 A method for preparing a fluorine-containing lubricating oil gel comprises the following steps: S1. Dissolve 10 mmol of maleimide undecanoic acid, 11 mmol of 2H-perfluoro-1-decanol, 11 mmol of 1,3-dicyclohexylcarbodiimide and 0.5 mmol of 4-dimethylaminopyridine in 20 mL of dichloromethane.

[0074] The product was stirred at 300 rpm for 24 h at room temperature and purified by 200-mesh silica gel column chromatography using a mixed solvent of methanol: dichloromethane = 1:20 as the eluent, and named Gel.

[0075] S4: 50 mg of the gel was dispersed in 950 mg of 500SN oil at 80°C. After cooling, the gel was tested using an SRV5 fretting tribometer at 150°C, an amplitude of 1 mm, and a frequency of 25 Hz. Compared to pure 500SN oil, the friction coefficient of the carbon dot composite lubricant gel decreased from 0.150 to 0.107, and the wear spot volume was reduced by 33%.

[0076] Comparative Example 3 A method for preparing a fluorine-containing lubricating oil gel comprises the following steps: S1. Dissolve 10 mmol of maleimide undecanoic acid, 11 mmol of 2H-perfluoro-1-decanol, 11 mmol of 1,3-dicyclohexylcarbodiimide and 0.5 mmol of 4-dimethylaminopyridine in 20 mL of dichloromethane.

[0077] The product was stirred at 300 rpm for 24 h at room temperature and purified by 200-mesh silica gel column chromatography using a mixed solvent of methanol: dichloromethane = 1:20 as the eluent, and named Gel.

[0078] S4: 50 mg of the gel was dispersed in 950 mg of ANs oil at 80°C. After cooling, the gel was tested using an SRV5 fretting friction and wear tester at 150°C, an amplitude of 1 mm, and a frequency of 25 Hz. Compared with pure ANs oil, the friction coefficient of the carbon dot composite lubricant gel decreased from 0.153 to 0.115, and the wear spot volume was reduced by 64%.

[0079] Figure 1 This is a scanning electron microscope image of Gel@CDs-0.2 prepared in Examples 1-3 of the present invention, as shown in FIG. Figure 1 As shown in Figure 1, scanning electron microscopy (SEM) image a shows that the prepared carbon dot composite lubricating oil gel factor self-assembles into a fibrous structure with a fiber diameter of about 200 to 300 nm.

[0080] Figure 2Gel@CDs-0.2 and Gel prepared in Examples 1-3 and Comparative Examples 1-3 were added to PAO, 500SN, and ANs, respectively. The friction coefficient and wear volume of the lubricating oil gel at a concentration of 1 wt % were evaluated at 150°C, an amplitude of 1 mm, and a frequency of 25 Hz. Figure 2 In the figure, a is the friction coefficient curve of PAO, Gel and Gel@CDs-0.2 in PAO, b is the friction coefficient curve of 500SN, Gel and Gel@CDs-0.2 in 500SN, and c is the friction coefficient curve of ANs, Gel and Gel@CDs-0.2 in ANs. Figure 2 As shown in the figure, PAO, 500SN, and Ans all exhibit significant galling, with the friction coefficient fluctuating dramatically, rapidly rising to around 0.3 within a short period of time before plummeting and remaining above 0.15. The flat friction coefficients reached as high as 0.155, 0.150, and 0.153, respectively. The prepared carbon dot composite lubricant gel exhibited excellent lubrication performance at a concentration of 1 wt%, with average friction coefficients reduced to 0.108, 0.107, and 0.101, respectively. The friction coefficients were stable and showed no galling. (d) is a histogram of wear volume. Compared to pure lubricant, the wear volume of the carbon dot composite lubricant gel was statistically reduced by 48%, 58%, and 74%, respectively.

[0081] Figure 3 The stability photos of the carbon dot composite lubricating oil gels prepared in Examples 1 to 9 of the present invention are shown. The carbon dot composite lubricating oil gels maintained excellent stability with no refluxing after 12 months in different lubricating oils, demonstrating excellent lubricating oil adaptability.

[0082] It should be noted that when numerical ranges are mentioned in the present invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints may be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes preferred embodiments. Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they understand the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0083] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preparing a novel carbon dot composite lubricating oil gel factor, characterized in that: The following steps are involved: S1. Dissolve maleimide undecanoic acid, 2H-perfluoro-1-decanol, 1,3-dicyclohexylcarbodiimide and a catalyst in dichloromethane, stir at room temperature for 24 hours, and obtain a fluorinated gel factor by silica gel column chromatography in an eluent; S2, dissolving 1-furan borate and 2-aminothiophenol in methanol, adding sodium hydroxide and ultrasonically dispersing, then performing solvothermal treatment, and then performing alumina column chromatography in ethanol to obtain carbon dots; S3. Add a certain proportion of fluorine-containing gel factor and carbon dots into methanol, reflux with stirring, and remove the solvent under reduced pressure to obtain a novel carbon dot composite lubricating oil gel factor.

2. The method for preparing a novel carbon dot composite lubricating oil gel factor according to claim 1, characterized in that: The molar mass ratio of maleimide undecanoic acid, 2H- perfluoro-1-decanol, 1,3-dicyclohexylcarbodiimide and the catalyst in S1 is 1:1.1:1.1: (0.01 to 0.05); the volume of dichloromethane is 10 to 20 mL; The catalyst is one of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 4-dimethylaminopyridine.

3. The method for preparing a novel carbon dot composite lubricating oil gel factor according to claim 1, characterized in that: The rotation speed during the stirring process in S1 is 300-600 rpm, the de-eluent is a mixed solvent of methanol and dichloromethane, and the volume ratio of methanol to dichloromethane is 1:20; the silica gel particle size in the silica gel column chromatography is 100-300 mesh.

4. The method for preparing a novel carbon dot composite lubricating oil gel factor according to claim 1, characterized in that: The mass ratio of the 1-boronic acid furan to the sodium hydroxide in S2 is 1:(0.5-1.5), and the volume of the 2-aminothiophenol is 160-220 μL.

5. The method for preparing a novel carbon dot composite lubricating oil gel factor according to claim 1, characterized in that: The ultrasonic dispersion time in S2 is 10 to 15 minutes; the solvent thermal treatment temperature is 200°C to 220°C, and the time is 3 to 5 hours.

6. The method for preparing a novel carbon dot composite lubricating oil gel factor according to claim 1, characterized in that: The ratio of the fluorine-containing gel factor and the carbon dots in S3 is (5-10):

1.

7. The method for preparing the novel carbon dot composite lubricating oil gel factor according to claim 1, characterized in that: The reflux stirring temperature is 60-80°C, and the stirring time is 2-3h.

8. A novel carbon dot composite lubricating oil gel factor prepared by the preparation method according to any one of claims 1 to 7.

9. A use of the novel carbon dot composite lubricant gel factor according to claim 8 in lubricating oil, characterized in that: The novel carbon dot composite lubricant gel factor is dispersed in lubricant at 60-90° C. and cooled to room temperature.

10. The use according to claim 9, characterized in that The gel factor of the novel carbon dot composite lubricant is added to the lubricant in an amount of 1 to 6 wt %; the lubricant is one of Class III lubricant, Class IV lubricant, and Class V lubricant.

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