Preparation method and application of oil-soluble ionic liquid-carbon dot eutectic

Abstract

The present invention relates to a method for preparing an oil-soluble ionic liquid-carbon point eutectic, comprising the following steps: (1) preparing an ionic liquid: first adding n-butylamine to an excess of anhydrous ethanol and then dropping diisooctyl phosphate, or first adding n-octylamine and then dropping palmitic acid; then rapidly stirring the resulting solution at room temperature for 12 hours, rotary evaporation, vacuum drying, to obtain an ionic liquid diisooctyl phosphate n-butylammonium or palmitic acid n-octyl ammonium in a solid state at room temperature; (2) preparing carbon points: dodecylamine, anhydrous AlCl3 and o-dichlorobenzene oil bath pyrolysis to obtain carbon points; (3) preparing an ionic liquid-carbon point eutectic: adding 3 wt.%~10 wt.% of carbon points to the ionic liquid, then adding an excess of anhydrous ethanol, ultrasonically dissolving, vacuum drying, to obtain the corresponding ionic liquid-carbon point eutectic. At the same time, the present invention also discloses the application of the ionic liquid-carbon point eutectic. The preparation method of the present invention is simple, and has good oil solubility and room temperature fluidity as a lubricating oil additive.

Description

Technical Field

[0001] The present invention relates to the technical field of additives, and in particular to a preparation method of an oil-soluble ionic liquid-carbon dot eutectic and application thereof. Background Art

[0002] With the continuous advancement of industrial technology, material and energy losses caused by friction and wear account for about 3% of the national economy in developed countries. This proportion may be higher in developing countries where technological maintenance is relatively backward. Therefore, modern industrial technology and scientific research pay great attention to the research and development of advanced lubricating materials. In recent years, ionic liquids have gained widespread research interest in scientific research and industry due to their great potential in advanced lubricating materials. Compared with traditional lubricating materials, ionic liquids, as a new type of lubricating material, have the characteristics of non-volatility, non-flammability and high thermal stability. However, the solubility of ionic liquids in non-polar lubricating oils is extremely low, which greatly limits their application. In addition, low-melting-point ionic liquids have shown greater application potential due to their wide liquid range and are suitable for a wider range of industrial scenarios.

[0003] Carbon dots (CDs) are non-toxic and biocompatible nanomaterials composed of carbon-based material particles with a diameter of no more than 10 nm. Recently, carbon dots have been studied as lubricating additives in polar base oils and have shown excellent load-bearing capacity, anti-wear and interface repair capabilities. Compared with existing lubricating additives, carbon dots show extremely high lubrication efficiency and can still exert excellent tribological properties even at concentrations as low as 0.01 wt.%. However, the dispersion stability of carbon dots in non-polar base oils remains a challenge. This is mainly because the solid properties of carbon dots make them prone to agglomeration and precipitation in systems with weak solvation forces.

[0004] Deep eutectic solvents (DESs) are liquids formed by mixing two solids, resulting in a decrease in the lattice energy of the components. Their discovery has broadened the application range and functionality of materials to a certain extent.

[0005] Therefore, the present invention is intended to combine ionic liquids and carbon dots to synthesize a new eutectic to compound the advantages of the two materials. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing an oil-soluble ionic liquid-carbon dot eutectic which is simple and easy to implement.

[0007] Another technical problem to be solved by the present invention is to provide an application of the oil-soluble ionic liquid-carbon dot eutectic.

[0008] In order to solve the above problems, a method for preparing an oil-soluble ionic liquid-carbon dot eutectic according to the present invention comprises the following steps:

[0009] ⑴ Preparation of ionic liquids:

[0010] In excess anhydrous ethanol, n-butylamine is first added and then diisooctyl phosphate is added dropwise, or n-octylamine is first added and then palmitic acid is added dropwise; the resulting solution is then rapidly stirred at room temperature for 12 hours, ethanol is removed by rotary evaporation, and vacuum dried at 70° C. for 12 hours to obtain ionic liquid diisooctyl n-butylammonium phosphate ([N4HHH][DEHP]) or n-octyl ammonium palmitate ([N8HHH][PA]) which is solid at room temperature;

[0011] ⑵Preparation of carbon dots:

[0012] Dodecylamine, anhydrous AlCl3 and o-dichlorobenzene are added to a container equipped with a magnetic stirring and reflux device, and then heated to 140°C in an oil bath for 48 hours for pyrolysis. After the reaction is stopped, a mixture is obtained; after the mixture is naturally cooled to room temperature, it is first concentrated to remove part of the solvent, then passed through a silica gel column in two steps, and finally ethanol is removed by rotary evaporation. The obtained solid product is vacuum dried at 70°C for 12 hours to obtain carbon dots (CDs);

[0013] ⑶ Preparation of ionic liquid-carbon dot eutectic:

[0014] 3 wt.% to 10 wt.% of the carbon dots are added to the ionic liquid, and then an excess of anhydrous ethanol is added. After ultrasonic dissolution, the ethanol is removed by rotary evaporation, and the mixture is vacuum dried at 70°C for 12 hours to obtain the corresponding ionic liquid-carbon dot eutectic (IL-CD DESs).

[0015] In the step (1), the molar ratio of n-butylamine to diisooctyl phosphate is 1:1, and the molar ratio of n-octylamine to palmitic acid is 1:1.

[0016] In the step (2), the mass ratio of dodecylamine to anhydrous AlCl3 is 1.4-1.6:1; the mass volume ratio of dodecylamine to o-dichlorobenzene is 1:5-6.

[0017] An oil-soluble ionic liquid-carbon dot eutectic prepared by any of the methods described above.

[0018] The application of the oil-soluble ionic liquid-carbon dot eutectic as described above is characterized in that the oil-soluble ionic liquid-carbon dot eutectic is used as an additive in lubricating oil.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The ionic liquid-carbon dot eutectic of the present invention has a novel structure, a simple preparation method, does not contain active elements such as halogens and sulfur, and will not cause corrosion to moving parts such as bearings.

[0021] 2. The ionic liquid-carbon dot eutectic of the present invention can improve the oil solubility and fluidity of the ionic liquid and the carbon dots, and as a lubricating oil additive, has good oil solubility and room temperature fluidity, and has excellent friction reduction, anti-wear and extreme pressure properties.

[0022] 3. The present invention not only broadens the liquid range of ionic liquids and enhances their applicability, but also improves the dispersibility of carbon dots in base oils. In addition, when used as a non-polar base oil additive, the ionic liquid-carbon dot eutectic exhibits a significant synergistic effect in terms of oil solubility and lubricity, which is expected to promote the widespread application of ionic liquids, carbon dots and their eutectics as lubricant additives in the field of lubrication engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0024] Figure 1 These are appearance photos of low eutectic formed by the ionic liquid of the present invention and carbon dots with different mass fractions. DETAILED DESCRIPTION

[0025] A method for preparing an oil-soluble ionic liquid-carbon dot eutectic comprises the following steps:

[0026] ⑴ Preparation of ionic liquids:

[0027] In excess anhydrous ethanol, n-butylamine is first added and then diisooctyl phosphate (DEHP) is added dropwise, or n-octylamine is first added and then palmitic acid (PA) is added dropwise, the molar ratio of n-butylamine to diisooctyl phosphate is 1:1, and the molar ratio of n-octylamine to palmitic acid is 1:1. The resulting solution is then rapidly stirred at room temperature for 12 hours, the ethanol is removed by rotary evaporation, and vacuum dried at 70°C for 12 hours to obtain ionic liquid diisooctyl phosphate n-butylammonium ([N4HHH][DEHP]) or n-octylammonium palmitate ([N8HHH][PA]) which is solid at room temperature.

[0028] ⑵Preparation of carbon dots:

[0029] Dodecylamine, anhydrous AlCl3 and o-dichlorobenzene were added to a container equipped with a magnetic stirring and reflux device, and the mass ratio (g / g) of dodecylamine to anhydrous AlCl3 was 1.4~1.6:1; the mass volume ratio (g / mL) of dodecylamine to o-dichlorobenzene was 1:5~6. Then, the mixture was heated to 140℃ in an oil bath for 48 hours, and the reaction was stopped to obtain a mixture; after the mixture was naturally cooled to room temperature, it was first concentrated to remove part of the solvent, and then passed through a silica gel column in two steps, and finally the ethanol was removed by rotary evaporation, and the obtained solid product was vacuum dried at 70℃ for 12 hours to obtain carbon dots (CDs).

[0030] ⑶ Preparation of ionic liquid-carbon dot eutectic:

[0031] 3 wt.%~10 wt.% of carbon dots were added to the ionic liquid, and then excess anhydrous ethanol was added. After ultrasonic dissolution, the ethanol was removed by rotary evaporation and vacuum dried at 70°C for 12 hours to obtain the corresponding ionic liquid-carbon dot eutectic (IL-CDDESs).

[0032] An application of an oil-soluble ionic liquid-carbon dot eutectic, wherein the oil-soluble ionic liquid-carbon dot eutectic is applied as an additive in lubricating oil.

[0033] Example 1

[0034] In a 100 mL single-necked flask containing 30 mL of anhydrous ethanol, 0.05 mol of n-butylamine (3.66 g) was first added, and then an equal molar amount of diisooctyl phosphate (DEHP 0.05 mol, 16.12 g) was dropped. The resulting solution was then rapidly stirred at room temperature for 12 hours, and then the ethanol was removed by rotary evaporation, and vacuum dried at 70°C for 12 hours to obtain diisooctyl phosphate n-butylammonium ionic liquid (19.32 g) which was solid at room temperature and recorded as [N4HHH][DEHP].

[0035] In a 100 mL single-necked flask containing 30 mL of anhydrous ethanol, 0.05 mol of n-octylamine (6.46 g) was first added, and then an equal mole of palmitic acid (PA 0.05 mol, 12.82 g) was dropped. The resulting solution was then rapidly stirred at room temperature for 12 hours, the ethanol was removed by rotary evaporation, and vacuum dried at 70°C for 12 hours to obtain n-octyl ammonium palmitate ionic liquid (18.66 g) that was solid at room temperature, recorded as [N8HHH][PA].

[0036] 0.25 g of [N8HHH] [PA] was added to a 50 ml single-necked flask containing 0.75 g of [N4HHH] [DEHP], and then 10 ml of anhydrous ethanol was added to the flask, and the two ionic liquid mixtures were dissolved by ultrasound. The ethanol was removed by rotary evaporation, and then dried in a vacuum at 70°C for 12 hours to obtain an ionic liquid-ionic liquid eutectic, which was recorded as IL-IL DES.

[0037] Example 2

[0038] The preparation method of [N4HHH][DEHP] is the same as that in Example 1.

[0039] 9.26 g of raw material dodecylamine, 6.2 g of anhydrous AlCl3 and 50 mL of o-dichlorobenzene were added to a 250 mL three-necked flask with magnetic stirring and reflux device, and then heated to 140°C in an oil bath for 48 h for pyrolysis without gas protection. After stopping the reaction, the mixture was naturally cooled to room temperature, concentrated to remove part of the solvent, and passed through a silica gel column in two steps. The first step was to remove the solvent with n-hexane as the eluent, and the second step was to remove the raw material dodecylamine and other impurities with ethanol as the eluent. The ethanol was removed by rotary evaporation, and the solid product was vacuum dried at 70°C for 12 hours to obtain carbon dots, which were recorded as CDs.

[0040] 0.03 g of CD was added to a 50 ml single-necked flask containing 0.97 g of [N4HHH][DEHP]. Then 10 ml of anhydrous ethanol was added to the flask, and the mixture of ionic liquid and carbon dots was dissolved by ultrasound. The ethanol was removed by rotary evaporation, and then dried in a vacuum at 70°C for 12 hours to obtain an ionic liquid-carbon dot eutectic, which was recorded as IL-CD DES-1 and had an appearance as shown below: Figure 1 shown.

[0041] Example 3

[0042] The preparation method of [N4HHH][DEHP] is the same as that in Example 1.

[0043] The preparation method of CD is the same as that of Example 2.

[0044] 0.05 g of CD was added to a 50 ml single-necked flask containing 0.95 g of [N4HHH] [DEHP]. Then 10 ml of anhydrous ethanol was added to the flask, and the mixture of ionic liquid and carbon dots was dissolved by ultrasound. The ethanol was removed by rotary evaporation, and then dried in a vacuum at 70 ° C for 12 hours to obtain an ionic liquid-carbon dot eutectic, which was recorded as IL-CD DES-2 and had an appearance as shown below. Figure 1 shown.

[0045] Example 4

[0046] The preparation method of [N4HHH][DEHP] is the same as that in Example 1.

[0047] The preparation method of CD is the same as that of Example 2.

[0048] 0.07 CD was added to a 50 ml single-necked flask containing 0.93 g [N4HHH] [DEHP]. Then 10 ml of anhydrous ethanol was added to the flask, and the mixture of ionic liquid and carbon dots was dissolved by ultrasound. The ethanol was removed by rotary evaporation, and then dried in a vacuum at 70 ° C for 12 hours to obtain an ionic liquid-carbon dot eutectic, which was recorded as IL-CD DES-3 and had an appearance as shown below. Figure 1 shown.

[0049] Example 5

[0050] The preparation method of [N4HHH][DEHP] is the same as that in Example 1.

[0051] The preparation method of CD is the same as that of Example 2.

[0052] 0.10 CD was added to a 50 ml single-necked flask containing 0.90 g [N4HHH] [DEHP]. Then 10 ml of anhydrous ethanol was added to the flask, and the mixture of ionic liquid and carbon dots was dissolved by ultrasound. The ethanol was removed by rotary evaporation, and then dried in a vacuum at 70°C for 12 hours. The ethanol was removed by rotary evaporation, and then dried in a vacuum at 70°C for 12 hours to obtain an ionic liquid-carbon dot eutectic, which was recorded as IL-CD DES-4 and had an appearance as shown below. Figure 1 shown.

[0053] Depend on Figure 1 It can be seen that the ionic liquid-carbon dot eutectics prepared in Examples 2 to 5 all have good fluidity and are in a liquid state at room temperature.

[0054] Application of binary ionic liquid eutectic as lubricating oil additive

[0055] The tribological test was conducted on the fretting friction and wear tester SRV-V of Optimal Company. PAO 4 was selected as the base oil, the ionic liquid-carbon dot eutectic prepared in Examples 2-5 was selected as the additive, and the ionic liquid-ionic liquid eutectic prepared in Example 1 was used as the comparative additive. The amount of additive added was 1% by mass. The contact form of the test was ball-disc point contact, the upper sample was a Φ10 mm AISI 52100 steel ball, and the lower sample was a Φ10 mm×3.5 mm AISI52100 steel disc. The specific experimental conditions were: frequency 25 Hz, amplitude 1.0 mm, temperature 30±1°C, load 250 N, and the test results are shown in Table 1.

[0056] Table 1 Average friction coefficient and wear rate of oil samples

[0057]

[0058] As can be seen from Table 1, the base oil has a higher average friction coefficient and produces an extremely high average wear rate. The friction coefficient of PAO+1%IL-IL DES is also above 0.3, and leads to a higher wear rate, indicating that it is difficult to significantly improve the lubricity of the base oil using only ionic liquid eutectic as an additive. However, adding ionic liquid-carbon point eutectic as an additive can significantly improve the tribological properties of PAO base oil. In particular, the average friction coefficient of two oil samples formed as PAO additives by ionic liquid-carbon point eutectic IL-CD DES-2 and IL-CD DES-3 prepared by Example 3 and Example 4 is significantly reduced compared to the base oil, and the wear rate is also two orders of magnitude lower than the base oil.

[0059] In summary, the present invention can improve the oil solubility and fluidity of ionic liquids and carbon dots, and enhance the tribological properties of ionic liquid-carbon dot eutectics when used as additives. It is expected to promote the widespread application of ionic liquids, carbon dots and their eutectics as lubricant additives in the field of lubrication engineering.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an oil-soluble ionic liquid-carbon dot eutectic, comprising the following steps: ⑴ Preparation of ionic liquids: Firstly add n-butylamine to excess anhydrous ethanol and then drop diisooctyl phosphate; then quickly stir the resulting solution at room temperature for 12 hours, remove the ethanol by rotary evaporation, and vacuum dry at 70°C for 12 hours to obtain ionic liquid diisooctyl n-butylammonium phosphate which is solid at room temperature; ⑵Preparation of carbon dots: Dodecylamine, anhydrous AlCl3 and o-dichlorobenzene are added to a container equipped with a magnetic stirring and reflux device, and then heated to 140°C in an oil bath for pyrolysis for 48 hours. After the reaction is stopped, a mixture is obtained. After the mixture is naturally cooled to room temperature, it is first concentrated to remove part of the solvent, and then passed through a silica gel column in two steps. Finally, ethanol is removed by rotary evaporation. The obtained solid product is vacuum dried at 70°C for 12 hours to obtain carbon dots. ⑶ Preparation of ionic liquid-carbon dot eutectic: 5 wt.% to 7 wt.% of the carbon dots are added to the ionic liquid, and then an excess of anhydrous ethanol is added. After ultrasonic dissolution, the ethanol is removed by rotary evaporation, and vacuum drying is performed at 70°C for 12 hours to obtain the corresponding ionic liquid-carbon dot eutectic.

2. The method for preparing an oil-soluble ionic liquid-carbon dot eutectic according to claim 1, characterized in that: In the step (1), the molar ratio of n-butylamine to diisooctyl phosphate is 1:

1.

3. The method for preparing an oil-soluble ionic liquid-carbon dot eutectic according to claim 1, characterized in that: In the step (2), the mass ratio of dodecylamine to anhydrous AlCl3 is 1.4-1.6:1; the mass volume ratio of dodecylamine to o-dichlorobenzene is 1:5-6.

4. An oil-soluble ionic liquid-carbon dot eutectic prepared by the method according to any one of claims 1 to 3.

5. The use of an oil-soluble ionic liquid-carbon dot eutectic as claimed in claim 4, characterized in that: The oil-soluble ionic liquid-carbon dot eutectic is used as an additive in lubricating oil.

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