Self-adaptive lubrication eutectic gel lubricant as well as preparation method and application thereof

Abstract

The invention provides a self-adaptive lubrication eutectic gel lubricant as well as a preparation method and application thereof, and relates to the technical field of tribology. The eutectic gel lubricant with self-adaptive lubrication provided by the invention is prepared from the following preparation raw materials: a eutectic solvent, polyvinylpyrrolidone, MXene nanosheets, acrylamide, a cross-linking agent and a photoinitiator, the eutectic solvent comprises a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is choline chloride, and the hydrogen bond donor comprises one or more of ethylene glycol, urea, glycerol and polyethylene glycol. The eutectic gel lubricant provided by the invention not only shows good thermodynamic stability in a wide temperature range (-30 to 80 DEG C), but also has a relatively low friction coefficient and excellent self-adaptive lubricating performance, and can be used for preparing high-temperature-resistant lubricating oil under different working conditions. And under different temperatures, different friction pair conditions, different loads and different frequencies, the lubricating oil shows excellent antifriction and antiwear properties.

Description

Technical Field

[0001] The present invention relates to the technical field of tribology, and particularly to a eutectic gel lubricant with self - adaptive lubrication, a preparation method thereof, and an application thereof. Background Art

[0002] Hydrogels are three - dimensional network structures formed by cross - linking of high - molecular compounds, and they can rapidly absorb and retain a large amount of water in water. Due to their excellent biocompatibility and hydrophilicity, hydrogels have been widely used in fields such as biomedicine and soft robotics.

[0003] However, hydrogels are prone to performance instability problems such as dehydration, solidification, network collapse dissociation, or mechanical property degradation under high - temperature or low - temperature environments, which seriously affect their applications in the field of tribology. Developing a new gel system to overcome the limitations of traditional hydrogels in terms of poor thermal stability and environmental adaptability in lubricant applications has become a technical problem to be urgently solved. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a eutectic gel lubricant with self - adaptive lubrication, a preparation method thereof, and an application thereof. The eutectic gel lubricant provided by the present invention has self - adaptive lubrication characteristics and thermodynamic stability under different environmental conditions.

[0005] In order to achieve the above - mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a eutectic gel lubricant with self - adaptive lubrication, comprising the following preparation raw materials:

[0007] Deep eutectic solvent, polyvinylpyrrolidone, MXene nanosheets, acrylamide, cross - linker, and photo - initiator; the deep eutectic solvent includes a hydrogen - bond acceptor and a hydrogen - bond donor, the hydrogen - bond acceptor is choline chloride, and the hydrogen - bond donor includes one or more of ethylene glycol, urea, glycerol, and polyethylene glycol, and the molar ratio of the hydrogen - bond acceptor to the hydrogen - bond donor is 1:2.

[0008] Preferably, the deep eutectic solvent is obtained by mixing the hydrogen - bond acceptor and the hydrogen - bond donor under heating conditions, the heating temperature is 50 - 80 °C, and the mixing time is 1 - 4 h.

[0009] Preferably, the weight - average molecular weight of the polyvinylpyrrolidone is 5800 - (1.3×10 6 )

[0010] Preferably, the cross - linker includes N,N - methylenebisacrylamide; the photo - initiator includes 2,2 - dimethoxy - 2 - phenylacetophenone.

[0011] Preferably, the dosage ratio of polyvinylpyrrolidone to the deep eutectic solvent is 0.1 - 0.3 g:1 mL.

[0012] Preferably, the dosage ratio of MXene nanosheets to the deep eutectic solvent is 4 - 6 mg:1 mL.

[0013] Preferably, the dosage ratio of acrylamide to the deep eutectic solvent is 0.15 - 0.23 g:2 mL.

[0014] Preferably, the mass ratio of the crosslinking agent to acrylamide is 1:30 - 1:10, and the mass ratio of the photoinitiator to acrylamide is 1:15 - 1:10.

[0015] The present invention provides a method for preparing the self - adaptive lubricating eutectic gel lubricant according to the above - mentioned technical solutions, comprising the following steps:

[0016] Mix the deep eutectic solvent, polyvinylpyrrolidone, MXene nanosheets, acrylamide, crosslinking agent and photoinitiator, and carry out polymerization under ultraviolet light to obtain the self - adaptive lubricating eutectic gel lubricant.

[0017] Preferably, the polymerization time is 15 - 40 min.

[0018] The present invention provides the application of the self - adaptive lubricating eutectic gel lubricant according to the above - mentioned technical solutions or the self - adaptive lubricating eutectic gel lubricant prepared by the preparation method according to the above - mentioned technical solutions in the field of friction lubrication.

[0019] The present invention provides a eutectic gel lubricant with adaptive lubrication, comprising the following raw materials for preparation: deep eutectic solvent, polyvinylpyrrolidone, MXene nanosheets, acrylamide, crosslinking agent and photoinitiator; the deep eutectic solvent comprises a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is choline chloride, and the hydrogen bond donor comprises one or more of ethylene glycol, urea, glycerol and polyethylene glycol. In the present invention, choline chloride is used as the hydrogen bond acceptor, and one or more of ethylene glycol, urea, glycerol and polyethylene glycol are used as the hydrogen bond donor to form a deep eutectic solvent (DES). On the one hand, the deep eutectic solvent has good thermodynamic stability, thus ensuring good temperature resistance when it is used as the solvent of the eutectic gel. On the other hand, the deep eutectic solvent itself has a low viscosity, which can prevent the influence of the friction resistance caused by the excessive viscosity of the formed eutectic gel on the lubrication effect. The present invention uses MXene nanosheets with excellent lubrication characteristics as the lubricating phase, which can endow the gel with good anti-friction and anti-wear capabilities. At the same time, in order to avoid the flocculation of MXene nanosheets in the deep eutectic solvent, polyvinylpyrrolidone is used as a stabilizer to improve the dispersion stability of MXene nanosheets in DES. The present invention uses acrylamide as a polymerization monomer, which can form a gel network through photoinitiated polymerization to prevent the creep and leakage of the deep eutectic solvent. The obtained eutectic gel not only has covalent crosslinking, but also has non-covalent interactions such as hydrogen bonds between the solvent, polyvinylpyrrolidone and MXene nanosheets, significantly improving the thermal stability and mechanical strength of the material and enhancing its stability and environmental adaptability. Through the special design of the overall composition and structure of the gel system, the eutectic gel lubricant provided by the present invention has good adaptive lubrication characteristics and thermodynamic stability under different environmental conditions.

[0020] The results of the examples show that the eutectic gel lubricant provided by the present invention not only exhibits good thermodynamic stability in a wide temperature range (-30 to 80 °C), but also has a low friction coefficient and excellent adaptive lubrication performance. When the eutectic gel lubricant is applied to a steel / steel friction pair, at a load of 20 N, a frequency of 25 Hz and room temperature, the friction coefficient is 0.055. Moreover, the eutectic gel lubricant can exhibit excellent anti-friction and anti-wear performance under different working conditions, such as different temperature ranges (-30 to 80 °C), different friction pairs (9Cr18Mo, polyoxymethylene, polypropylene, polyamide), different loads (10 to 70 N) and frequencies (10 to 50 Hz), thus overcoming the limitations of traditional hydrogels in lubricant applications, such as poor thermal stability, poor environmental adaptability and low load-bearing capacity.

[0021] The present invention provides a preparation method of the eutectic gel lubricant with adaptive lubrication as described in the above technical solution. The present invention prepares a eutectic gel lubricant with excellent friction reduction and anti-wear performance and adaptive lubrication through simple mixing and photoinitiated polymerization. The process is simple, the preparation conditions are mild, the raw materials are green, safe and environmentally friendly. Description of the Drawings

[0022] Figure 1 Photographs of MXene nanosheets dispersed in a deep eutectic solvent with the addition of polyvinylpyrrolidone prepared in Example 1 and MXene nanosheets dispersed in a deep eutectic solvent prepared in Comparative Example 1;

[0023] Figure 2 Photograph of the eutectic gel lubricant prepared in Example 1;

[0024] Figure 3 Graph of the storage modulus of the eutectic gel lubricant prepared in Example 1 varying with temperature ( Figure 3 a) in Figure 3 and DSC curve (

[0025] Figure 4 b) in

[0026] Figure 5 Graph of the friction coefficient of the eutectic gel lubricant prepared in Example 1 varying with time; Figure 5 In

[0027] Figure 6 a is the friction curve at -30 °C, b is the friction curves at different temperatures, c is the friction curves at different frequencies, and d is the friction curves at different loads;

[0028] Figure 7 Graph of the friction coefficient of the eutectic gel lubricants prepared in Comparative Example 1, Comparative Example 2, Comparative Example 3 and Example 1 varying with time;

[0029] Figure 8 Graph of the friction coefficient of the eutectic gel lubricants prepared in Example 1, Example 2, Example 3 and Example 4 varying with time;

[0030] Figure 9 Photographs of MXene nanosheets dispersed in a deep eutectic solvent with the addition of polyvinylpyrrolidone prepared in Example 5, Example 6 and Example 7 and MXene nanosheets dispersed in a deep eutectic solvent prepared in Comparative Example 4, Comparative Example 5 and Comparative Example 6;

[0031] Figure 10 Graph showing the variation of the friction coefficient of the eutectic gel lubricant prepared in Example 5 and Comparative Example 4 with time;

[0032] Figure 11 Graph showing the variation of the friction coefficient of the eutectic gel lubricant prepared in Example 6 and Comparative Example 5 with time;

[0033] Figure 12 Graph showing the variation of the friction coefficient of the eutectic gel lubricant prepared in Example 7 and Comparative Example 6 with time. Detailed implementation mode

[0034] The present invention provides a eutectic gel lubricant for self - adaptive lubrication, comprising the following preparation raw materials:

[0035] Deep eutectic solvent, polyvinylpyrrolidone, MXene nanosheets, acrylamide, cross - linker and photo - initiator; the deep eutectic solvent comprises a hydrogen - bond acceptor and a hydrogen - bond donor, the hydrogen - bond acceptor is choline chloride, the hydrogen - bond donor comprises one or more of ethylene glycol, urea, glycerol and polyethylene glycol, and the molar ratio of the hydrogen - bond acceptor to the hydrogen - bond donor is 1:2.

[0036] In the present invention, unless otherwise specified, the raw materials involved are well - known commercially available products in the art.

[0037] The eutectic gel lubricant for self - adaptive lubrication provided by the present invention comprises a deep eutectic solvent (DES). In the present invention, the deep eutectic solvent comprises a hydrogen - bond acceptor and a hydrogen - bond donor, the hydrogen - bond acceptor is choline chloride (ChCl), the hydrogen - bond donor comprises one or more of ethylene glycol (EG), urea (Urea), glycerol (Gly) and polyethylene glycol (PEG), the weight - average molecular weight of the polyethylene glycol is preferably 200 - 400; the molar ratio of the hydrogen - bond acceptor to the hydrogen - bond donor is 1:2.

[0038] In the present invention, the deep eutectic solvent is preferably obtained by mixing the hydrogen - bond acceptor and the hydrogen - bond donor under heating conditions. In the present invention, the heating temperature is preferably 50 - 80 °C, and can be 50, 55, 60, 70 or 80 °C; the mixing is preferably carried out under stirring conditions, the stirring speed is preferably 450 rpm; the mixing time is preferably 1 - 4 h, and can be 1, 2, 3 or 4 h, specifically based on obtaining a clear and transparent liquid. The present invention can obtain the deep eutectic solvent by a simple heating and stirring method.

[0039] In the present invention, the deep eutectic solvent itself has a relatively low viscosity. Therefore, when it is used as a solvent to form a eutectic gel lubricant, it will not generate a large frictional resistance due to excessive viscosity, which will affect the lubrication effect. The deep eutectic solvent has good thermodynamic stability, thus ensuring excellent temperature resistance when it is used as the solvent of the eutectic gel. In addition, the deep eutectic solvent is inexpensive, readily available, and environmentally friendly.

[0040] The eutectic gel lubricant for adaptive lubrication provided by the present invention includes MXene nanosheets. In the present invention, the dosage ratio of the MXene nanosheets to the deep eutectic solvent is preferably 4 - 6 mg:1 mL, and it can be 4 mg:1 mL, 5 mg:1 mL, or 6 mg:1 mL. In the present invention, the MXene nanosheets are preferably Ti 3 C 2 T x MXene nanosheets. The present invention has no special requirements for the source of the Ti 3 C 2 T x MXene nanosheets. They can be commercially available products or prepared by the preparation methods well-known to those skilled in the art. In the examples of the present invention, the Ti 3 C 2 T x MXene nanosheets are prepared by in-situ etching of Ti 3 AlC 2 MAX phase powder. The specific steps are preferably as follows:

[0041] Dissolve lithium fluoride (LiF) in hydrochloric acid solution, and slowly add Ti 3 AlC 2 MAX phase powder to carry out an etching reaction to obtain an etching reaction solution;

[0042] Centrifuge and wash the etching reaction solution with water until the pH value of the solution reaches a neutral state. Take the lower-layer precipitate, add water, carry out ultrasonic exfoliation under the protection of an inert gas, and then centrifuge to separate the upper-layer clear liquid to obtain an aqueous dispersion of MXene nanosheets.

[0043] In the present invention, the concentration of the hydrochloric acid solution is preferably 6 - 12 mol / L, and the dosage ratio of the hydrochloric acid solution to lithium fluoride is preferably 20 mL:1.6 g; the Ti 3 AlC 2The mass ratio of the MAX phase powder to lithium fluoride is preferably 1:1.6; the etching reaction is preferably carried out under heating and stirring, the heating temperature is preferably 35-45 °C, which can be 35, 40 or 45 °C, and the etching reaction time is preferably 24-36 h, which can be 24, 30 or 36 h. In the present invention, the rotation speed of the centrifugal cleaning is preferably 3500 rpm, the centrifugal cleaning is carried out multiple times, and the time of each centrifugal cleaning is preferably 5 min. In the present invention, the inert gas can be argon, and the introduction of the inert gas can remove the dissolved oxygen in the system; the time of the ultrasonic exfoliation is preferably 1-4 h, and the ultrasonic exfoliation is used to exfoliate the MXene multi-layer to few-layer nanosheets. In the present invention, the concentration of the aqueous dispersion of the MXene nanosheets is preferably 12-18 mg / mL.

[0044] The present invention uses MXene nanosheets with excellent lubrication characteristics as the lubricating phase, which can endow the eutectic gel lubricant with good anti-friction and anti-wear capabilities.

[0045] The self-adaptive lubricating eutectic gel lubricant provided by the present invention includes polyvinylpyrrolidone (PVP). In the present invention, the weight-average molecular weight of the polyvinylpyrrolidone is preferably 5800-(1.3×10 6 ), in the examples of the present invention, the weight-average molecular weight of the polyvinylpyrrolidone is 8000. In the present invention, the dosage ratio of the polyvinylpyrrolidone to the deep eutectic solvent is preferably 0.1-0.3 g:1 mL, which can be 0.1 g:1 mL, 0.2 g:1 mL or 0.3 g:1 mL.

[0046] The present invention uses polyvinylpyrrolidone as a stabilizer, which can improve the dispersion stability of MXene nanosheets in the deep eutectic solvent (DES). At the same time, the introduction of polyvinylpyrrolidone also provides a certain lubrication effect. The results of the examples show that after promoting the dispersion of MXene in the deep eutectic solvent (ChCl-EG) by using polyvinylpyrrolidone as a stabilizer, the friction coefficient of the eutectic gel lubricant can be reduced by 80%. This method is also applicable to the gel lubricants formed by using other ChCl-type deep eutectic solvents as solvents.

[0047] The eutectic gel lubricant with adaptive lubrication provided by the present invention comprises acrylamide, a crosslinking agent and a photoinitiator. In the present invention, the crosslinking agent preferably comprises N,N'-methylenebisacrylamide, and the N,N'-methylenebisacrylamide forms crosslinking points with polyacrylamide chains through its two reactive double bonds, thereby constructing a three-dimensional network structure; the photoinitiator preferably comprises 2,2-dimethoxy-2-phenylacetophenone. In the present invention, the dosage ratio of acrylamide to the deep eutectic solvent is preferably 0.15-0.23 g:2 mL, and can be 0.15 g:2 mL, 0.16 g:2 mL, 0.17 g:2 mL, 0.18 g:2 mL, 0.19 g:2 mL, 0.2 g:2 mL, 0.21 g:2 mL, 0.22 g:2 mL or 0.23 g:2 mL. In the present invention, when the amount of acrylamide is too low, a gel state cannot be formed, and when the amount of acrylamide is too high, the internal resistance of the gel network increases due to the increase in the degree of polymerization inside the gel, resulting in a decrease in the lubrication effect of the gel. The present invention limits the content of acrylamide monomers in the system so that the final state of the synthesized eutectic gel presents a semi-solid state, thereby participating in lubrication as a lubricant during the friction process and being more adaptable to the friction contact interface than traditional bulk hydrogels. In the present invention, the mass ratio of the crosslinking agent to acrylamide is preferably 1:30-1:10, and can be 1:30, 1:25, 1:20, 1:15 or 1:10, and the mass ratio of the photoinitiator to acrylamide is preferably 1:15-1:10, and can be 1:15, 1:14, 1:13, 1:12, 1:11 or 1:10.

[0048] In the present invention, as a polymerization monomer, acrylamide can form a gel network through photoinitiated polymerization under the action of a crosslinking agent and a photoinitiator, preventing the creep and leakage of the deep eutectic solvent, and finally obtaining a eutectic gel.

[0049] The present invention provides a eutectic gel lubricant based on a deep eutectic solvent. The eutectic gel lubricant has adaptive lubrication characteristics and thermodynamic stability under different environmental conditions, and can form a stable transfer film during the friction process, reducing the direct contact between friction pairs, thereby reducing wear and increasing the load-carrying capacity. The eutectic gel lubricant provided by the present invention not only exhibits good thermodynamic stability in a wide temperature range (-30 to 80 °C), but also has a low friction coefficient and excellent adaptive lubrication performance. Under different load and frequency conditions, the eutectic gel lubricant can maintain excellent lubrication effects, providing new ideas for the development of high-performance lubricating soft materials, which is of great significance for reducing energy loss, improving mechanical efficiency and extending the service life of equipment.

[0050] The present invention provides a preparation method for the eutectic gel lubricant with adaptive lubrication described in the above technical solutions, comprising the following steps:

[0051] Mix the eutectic solvent, polyvinylpyrrolidone, MXene nanosheets, acrylamide, crosslinking agent and photoinitiator, and carry out polymerization under ultraviolet light to obtain the self-adaptive lubricating eutectic gel lubricant.

[0052] In the present invention, the mixing method is preferably as follows:

[0053] Add polyvinylpyrrolidone to the eutectic solvent and carry out the first stirring and mixing to obtain a first mixed solution;

[0054] After carrying out the second stirring and mixing of the first mixed solution with the aqueous dispersion of MXene nanosheets, heat and dry the water to obtain a second mixed solution;

[0055] Add acrylamide, crosslinking agent and photoinitiator to the second mixed solution in sequence and carry out the third stirring and mixing.

[0056] The present invention has no special requirements for the time of the first stirring and mixing, the second stirring and mixing and the third stirring and mixing, and it is only necessary to ensure that the components are mixed evenly. Among them, the time of the first stirring and mixing can be 6-8 h, the time of the second stirring and mixing can be 10-20 min, and the time of the third stirring and mixing can be 10-20 min. In the present invention, the aqueous dispersion of MXene nanosheets is preferably the aqueous dispersion of MXene nanosheets prepared by the above technical solution, the heating temperature is preferably 60 °C, and the heating can be carried out in a vacuum oven. The present invention preferably adds acrylamide to the second mixed solution first, stirs evenly, and then adds the crosslinking agent and photoinitiator thereto; in order to promote the faster dissolution of each component, the second stirring and mixing can be carried out under heating conditions. The present invention can obtain the precursor solution of the gel by using a simple stirring method.

[0057] In the present invention, the polymerization time is preferably 15-40 min, and can be 15, 20, 30 or 40 min; the polymerization can be carried out at room temperature.

[0058] The preparation method provided by the present invention has a simple process, can be prepared by a simple liquid-phase reaction, has low cost and is environmentally friendly, and maximally avoids environmental pollution.

[0059] The present invention provides the application of the eutectic gel lubricant with self-adaptive lubrication described in the above technical solution or the eutectic gel lubricant with self-adaptive lubrication prepared by the preparation method described in the above technical solution in the field of friction lubrication. The present invention has no special requirements for the application method, and the application method of the gel lubricant well-known to those skilled in the art can be adopted. The eutectic gel lubricant provided by the present invention not only has excellent friction reduction and anti-wear performance, but also can maintain its lubrication performance under different friction conditions, such as under different temperatures, loads, frequencies and friction pairs, it can all exhibit excellent lubrication performance, can adapt to different environments, and is expected to be widely applied in multiple fields, especially in application scenarios that require high stability and self-adaptive lubrication performance.

[0060] In order to further illustrate the present invention, the following examples are used to describe in detail the self-adaptive lubricating eutectic gel lubricant provided by the present invention, its preparation method and application, but they cannot be understood as limiting the protection scope of the present invention.

[0061] In each of the examples and comparative examples, the preparation method of the MXene (Ti 3 C 2 T x MXene) nanosheet aqueous dispersion is as follows:

[0062] Dissolve LiF in 20 mL of 9M HCl solution, and slowly add Ti 3 AlC 2 MAX phase powder. Among them, the masses of the Ti 3 AlC 2 MAX phase powder and LiF are 1 g and 1.6 g respectively. Heat the above mixed solution at 40 °C and continuously stir for 24 h for sufficient etching; after the reaction is completed, wash by centrifugation with water (rotation speed 3500 r / min) until the pH value of the solution reaches neutral; then take the lower layer precipitate and add an appropriate amount of water, and ultrasonically exfoliate for 2 h under the protection of argon, and then perform centrifugal separation again (rotation speed 3500 r / min) to obtain the upper layer liquid, and finally obtain the MXene nanosheet (i.e., Ti 3 C 2 T x MXene few-layer nanosheet) aqueous dispersion with a concentration of 15 mg / mL.

[0063] In Examples 1 to 4, the preparation method of the deep eutectic solvent is as follows:

[0064] Weigh 1.3963 g of choline chloride (ChCl) and 1.2414 g of ethylene glycol (EG) (the molar ratio of choline chloride to ethylene glycol is 1:2), mix the two and place them in a 25 mL round-bottom flask and seal it, heat and stir at 50 °C for 2 h (450 rpm), and the obtained clear and transparent liquid is the deep eutectic solvent.

[0065] Example 1

[0066] An eutectic gel lubricant with self - adaptive lubrication, the preparation steps are as follows:

[0067] (1) Weigh 0.4 g of polyvinylpyrrolidone (PVP, M w = 8000) solid and add it to 2 mL of deep eutectic solvent, stir for 6 h to obtain a uniformly dispersed solution.

[0068] (2) Mix the aqueous dispersion of Ti 3 C 2 T x MXene few - layer nanosheets with the deep eutectic solvent added with PVP obtained in step (1), stir evenly, and place it in a vacuum oven to dry the water at 60 °C. Finally, the concentration of MXene nanosheets in the mixed solution (relative to the deep eutectic solvent) is 5 mg / mL.

[0069] (3) Add 0.15 g of acrylamide to the mixed solution prepared in step (2), stir evenly, then add 10 mg of N,N - methylenebisacrylamide and 11.3 mg of photoinitiator (2,2 - dimethoxy - 2 - phenylacetophenone). After all components are completely dissolved, place the final mixed solution in a petri dish and carry out photo - initiated polymerization under the irradiation of an ultraviolet lamp for 20 min to finally obtain the self - adaptive lubrication DES - PVP - MXene eutectic gel lubricant (abbreviated as DPM eutectic gel lubricant).

[0070] Comparative Example 1

[0071] An eutectic gel lubricant, the preparation steps are as follows:

[0072] (1) Add the aqueous dispersion of Ti 3 C 2 T x MXene few - layer nanosheets to 2 mL of deep eutectic solvent (the same as in Example 1), mix and stir evenly, and place it in a vacuum oven to dry the water at 60 °C. Finally, the concentration of MXene nanosheets in the mixed solution is 5 mg / mL.

[0073] (2) Add 0.15 g of acrylamide to the mixed solution prepared in step (1), stir evenly, then add 10 mg of N,N - methylenebisacrylamide and 11.3 mg of photoinitiator (2,2 - dimethoxy - 2 - phenylacetophenone). After all components are completely dissolved, place the final mixed solution in a petri dish and carry out photo - initiated polymerization under the irradiation of an ultraviolet lamp for 20 min to finally obtain the DES - MXene eutectic gel lubricant (abbreviated as DM eutectic gel lubricant).

[0074] Comparative Example 2

[0075] A eutectic gel lubricant is prepared as follows:

[0076] Add 0.15 g of acrylamide to 2 mL of a deep eutectic solvent (the same as in Example 1). After stirring evenly, add 10 mg of N,N-methylenebisacrylamide and 11.3 mg of a photoinitiator (2,2-dimethoxy-2-phenylacetophenone). After all components are completely dissolved, place the final mixed solution in a petri dish and carry out photoinitiated polymerization under ultraviolet light irradiation for 20 min to finally obtain a DES eutectic gel lubricant (abbreviated as D eutectic gel lubricant).

[0077] Comparative Example 3

[0078] A eutectic gel lubricant is prepared as follows:

[0079] (1) Weigh 0.4 g of polyvinylpyrrolidone (PVP, M w = 8000) solid and add it to 2 mL of a deep eutectic solvent (the same as in Example 1). Stir for 6 h to obtain a uniformly dispersed solution.

[0080] (2) Add 0.15 g of acrylamide to the mixed solution prepared in step (1). After stirring evenly, add 10 mg of N,N-methylenebisacrylamide and 11.3 mg of a photoinitiator (2,2-dimethoxy-2-phenylacetophenone). After all components are completely dissolved, place the final mixed solution in a petri dish and carry out photoinitiated polymerization under ultraviolet light irradiation for 20 min to finally obtain an adaptively lubricating DES-PVP eutectic gel lubricant (abbreviated as DP eutectic gel lubricant).

[0081] Figure 1 It is a physical picture of the deep eutectic solvent dispersed with MXene nanosheets after adding polyvinylpyrrolidone prepared in Example 1 and a physical picture of the deep eutectic solvent dispersed with MXene nanosheets prepared in Comparative Example 1. It can be seen that when the lubricating phase MXene is added alone, flocculation occurs in the deep eutectic solvent, while after pre-adding the stabilizer PVP, MXene can be uniformly dispersed in the whole system.

[0082] Figure 2 It is a physical picture of the eutectic gel lubricant prepared in Example 1. It can be seen that MXene remains uniformly dispersed in it and does not flow when inverted, preliminarily proving the formation of a solid-like gel substance.

[0083] Figure 3 It is a graph of the storage modulus of the eutectic gel lubricant prepared in Example 1 varying with temperature ( Figure 3 a in) and a DSC curve graph ( Figure 3 b in). From Figure 3It can be seen that the storage modulus of the eutectic gel lubricant at 100 °C is greater than the loss modulus, and it remains in the gel state. Moreover, it can be seen from the DSC curve that there are no peaks in the test range of -70 °C to 100 °C, indicating good thermal stability.

[0084] Figure 4 It is a graph showing the change of the friction coefficient of the eutectic gel lubricant prepared in Example 1 with time. The friction test conditions are as follows: at room temperature, with a steel / steel friction pair (the upper friction pair is a steel ball and the lower friction pair is a steel block, and the material of the steel is 9Cr18Mo), a load of 20 N, a frequency of 25 Hz, and a stroke of 1 mm. During the whole test process, the friction coefficient is maintained at about 0.055, indicating good lubrication performance.

[0085] Figure 5 It is a graph showing the change of the friction coefficient of the eutectic gel lubricant prepared in Example 1 with time at different temperatures, loads and frequencies. Figure 5 Among them, a is the friction curve at -30 °C, and the average friction coefficient is 0.068; b is the friction curve at different temperatures, and the friction coefficient decreases to 0.053 at the lowest with the increase of temperature, and the average friction coefficient is 0.10; c is the friction curve at different frequencies, and the friction coefficient gradually decreases to 0.04 with the increase of frequency, and the average friction coefficient is 0.073; d is the friction curve at different loads, and the friction coefficient gradually decreases to 0.04 with the increase of load, and the average friction coefficient is 0.089 (note: Figure 5 except for temperature in a and b, frequency in c, and load in d, other friction test conditions are the same as those in Figure 4 the corresponding friction test conditions). It can be seen that the eutectic gel lubricant has good lubrication self - adaptability to the changing environment. Even at -30 °C and different loads and frequencies, it can maintain a low friction coefficient.

[0086] Figure 6 It is a graph showing the change of the friction coefficient of Example 1 with time under different friction pairs. Figure 6 In it, POM, PP and PA respectively represent replacing the lower friction pair with polyoxymethylene, polypropylene and polyamide. Except for the lower friction pair, other friction test conditions are the same as those in Figure 4 the corresponding friction test conditions, and the corresponding friction coefficients are 0.038, 0.036 and 0.065 respectively. Figure 6 Steel in it represents the steel / steel friction pair. It can be seen that the eutectic gel lubricant can maintain its good lubrication performance when the lower friction pair is a steel block or different polymer blocks.

[0087] Figure 7Curves showing the variation of the friction coefficient of the eutectic gel lubricants prepared in Comparative Example 1, Comparative Example 2, Comparative Example 3, and Example 1 with time (the friction test conditions are the same as those Figure 4 corresponding friction test conditions). As can be seen from Figure 7 , the anti-friction effect of eutectic gels D and DM is extremely poor. The introduction of PVP not only serves as a stabilizer to promote the uniform dispersion of MXene in the deep eutectic solvent system but also provides a certain lubricating effect. Therefore, the introduction of MXene also exerts the excellent lubricating performance of two-dimensional lubricating materials. Compared with eutectic gel D, the friction coefficient of DPM gel is reduced by 80%.

[0088] Example 2

[0089] An adaptive lubricating eutectic gel lubricant is prepared as follows:

[0090] (1) Weigh 0.4 g of polyvinylpyrrolidone (PVP, M w = 8000) solid and add it to 2 mL of deep eutectic solvent, and stir for 6 h to obtain a uniformly dispersed solution.

[0091] (2) Mix the aqueous dispersion of Ti 3 C 2 T x MXene few-layer nanosheets with the deep eutectic solvent added with PVP obtained in step (1), stir evenly, and place it in a vacuum oven to dry the water at 60 °C. Finally, the concentration of MXene nanosheets in the mixed solution is 5 mg / mL.

[0092] (3) Add 0.19 g of acrylamide to the mixed solution prepared in step (2), stir evenly, then add 10 mg of N,N'-methylenebisacrylamide and 11.3 mg of photoinitiator (2,2-dimethoxy-2-phenylacetophenone). After all components are completely dissolved, place the final mixed solution in a petri dish and carry out photoinitiated polymerization under the irradiation of an ultraviolet lamp for 20 min to finally obtain the adaptive lubricating DPM eutectic gel lubricant.

[0093] Example 3

[0094] An adaptive lubricating eutectic gel lubricant is prepared as follows:

[0095] (1) Weigh 0.4 g of polyvinylpyrrolidone (PVP, M w = 8000) solid and add it to 2 mL of deep eutectic solvent, and stir for 6 h to obtain a uniformly dispersed solution.

[0096] (2) Mix the aqueous dispersion of Ti 3 C 2 T xThe MXene few-layer nanosheet aqueous dispersion is mixed with the eutectic solvent added with PVP obtained in step (1) and stirred evenly, and then placed in a vacuum oven to dry the moisture at 60 °C. Finally, the concentration of MXene nanosheets in the mixed solution is 5 mg / mL.

[0097] (3) Add 0.21 g of acrylamide to the mixed solution prepared in step (2). After stirring evenly, add 10 mg of N,N'-methylenebisacrylamide and 11.3 mg of photoinitiator (2,2-dimethoxy-2-phenylacetophenone). After all components are completely dissolved, place the final mixed solution in a petri dish and carry out photoinitiated polymerization under the irradiation of an ultraviolet lamp for 20 min to finally obtain the self-adaptive lubricating DPM eutectic gel lubricant.

[0098] Example 4

[0099] A self-adaptive lubricating eutectic gel lubricant is prepared according to the following steps:

[0100] (1) Weigh 0.4 g of polyvinylpyrrolidone (PVP, M w = 8000) solid and add it to 2 mL of eutectic solvent, and stir for 6 h to obtain a uniformly dispersed solution.

[0101] (2) Mix the aqueous dispersion of Ti 3 C 2 T x MXene few-layer nanosheets with the eutectic solvent added with PVP obtained in step (1), stir evenly, and place it in a vacuum oven to dry the moisture at 60 °C. Finally, the concentration of MXene nanosheets in the mixed solution is 5 mg / mL.

[0102] (3) Add 0.23 g of acrylamide to the mixed solution prepared in step (2). After stirring evenly, add 10 mg of N,N'-methylenebisacrylamide and 11.3 mg of photoinitiator (2,2-dimethoxy-2-phenylacetophenone). After all components are completely dissolved, place the final mixed solution in a petri dish and carry out photoinitiated polymerization under the irradiation of an ultraviolet lamp for 20 min to finally obtain the DPM self-adaptive eutectic gel lubricant.

[0103] Figure 8 The curve graph of the friction coefficient of the eutectic gel lubricants prepared in Example 1, Example 2, Example 3 and Example 4 changing with time (the friction test conditions are the same as the Figure 4 corresponding friction test conditions). From Figure 8It can be seen that when the amount of acrylamide is 0.15 g, the lubricating performance is optimal, and the friction coefficient is 0.055. When the amounts of acrylamide are 0.19 g, 0.21 g, and 0.23 g (Examples 2, 3, and 4), the corresponding friction coefficients are 0.075, 0.070, and 0.082, respectively. When the amount of acrylamide is too low, a gel state cannot be formed. When the content of acrylamide is increased, due to the increase in the degree of polymerization inside the gel, the internal resistance of the gel network becomes larger, resulting in a decrease in its lubricating effect.

[0104] Example 5

[0105] An eutectic gel lubricant with self - adaptation lubrication, the preparation steps are as follows:

[0106] (1) Weigh 3.4908 g of choline chloride (ChCl) and 3.003 g of urea (Urea), mix the two and place them in a 25 - mL round - bottom flask, seal it, and heat and stir at 80 °C for 1 h (450 rpm). The obtained clear and transparent liquid is the deep eutectic solvent.

[0107] (2) Weigh 0.4 g of polyvinylpyrrolidone (PVP, M w = 8000) solid and add it to 2 mL of the deep eutectic solvent prepared in step (1), stir for 6 h to obtain a uniformly dispersed solution.

[0108] (3) Mix the Ti 3 C 2 T x MXene few - layer nanosheet aqueous dispersion with the deep eutectic solvent added with PVP in step (2), stir evenly, and place it in a vacuum oven to dry the moisture at 60 °C. Finally, the concentration of MXene nanosheets in the mixed solution is 5 mg / mL.

[0109] (4) Add 0.15 g of acrylamide to the mixed solution prepared in step (3), stir evenly, then add 10 mg of N,N - methylenebisacrylamide and 11.3 mg of photo - initiator (2,2 - dimethoxy - 2 - phenylacetophenone). After all components are completely dissolved, place the final mixed solution in a petri dish and carry out photo - initiated polymerization under ultraviolet light irradiation for 20 min to finally obtain the DES - PVP - MXene (DPM) self - adaptive eutectic gel lubricant.

[0110] Comparative Example 4

[0111] An eutectic gel lubricant, the preparation steps are as follows:

[0112] (1) Weigh 3.4908 g of choline chloride (ChCl) and 3.003 g of urea (Urea), mix the two and place them in a 25 mL round-bottom flask, seal it, and heat and stir at 80 °C for 1 h (450 rpm). The resulting clear and transparent liquid is the deep eutectic solvent.

[0113] (2) Add the aqueous dispersion of Ti 3 C 2 T x few-layer MXene nanosheets to 2 mL of the deep eutectic solvent prepared in step (1), mix and stir evenly, and place it in a vacuum oven to dry the moisture at 60 °C. Finally, the concentration of MXene nanosheets in the mixture is 5 mg / mL.

[0114] (3) Add 0.15 g of acrylamide to the mixture prepared in step (2), stir evenly, and then add 10 mg of N,N'-methylenebisacrylamide and 11.3 mg of photoinitiator (2,2-dimethoxy-2-phenylacetophenone). After all components are completely dissolved, place the final mixture in a petri dish and carry out photoinitiated polymerization under ultraviolet light irradiation for 20 min to finally obtain the DES-MXene (DM) eutectic gel lubricant.

[0115] Example 6

[0116] An adaptive lubricating DPM eutectic gel lubricant is prepared as follows:

[0117] (1) Weigh 4.583 g of choline chloride (ChCl) and 5.98 g of glycerol (Gly), mix the two and place them in a 25 mL round-bottom flask, seal it, and heat and stir at 50 °C for 2 h (450 rpm). The resulting clear and transparent liquid is the deep eutectic solvent.

[0118] (2) Weigh 0.4 g of polyvinylpyrrolidone (PVP, M w = 8000) solid and add it to 2 mL of the deep eutectic solvent prepared in step (1), stir for 6 h to obtain a uniformly dispersed solution.

[0119] (3) Mix and stir evenly the aqueous dispersion of Ti 3 C 2 T x few-layer MXene nanosheets with the PVP-added deep eutectic solvent obtained in step (2), and place it in a vacuum oven to dry the moisture at 60 °C. Finally, the concentration of MXene nanosheets in the mixture is 5 mg / mL.

[0120] (4) Add 0.15 g of acrylamide to the mixed solution prepared in step (3). After stirring evenly, add 10 mg of N,N'-methylenebisacrylamide and 11.3 mg of photoinitiator (2,2-dimethoxy-2-phenylacetophenone). After all components are completely dissolved, place the final mixed solution in a petri dish and carry out photoinitiated polymerization under the irradiation of an ultraviolet lamp for 20 min to finally obtain the DES-PVP-MXene (DPM) self-adaptive eutectic gel lubricant.

[0121] Comparative Example 5

[0122] A eutectic gel lubricant, the preparation steps are as follows:

[0123] (1) Weigh 4.583 g of choline chloride (ChCl) and 5.98 g of glycerol (Gly). Mix the two and place them in a 25 mL round-bottom flask and seal it. Heat and stir at 50 °C for 2 h (450 rpm). The obtained clear and transparent liquid is the deep eutectic solvent.

[0124] (2) Add the Ti 3 C 2 T x MXene few-layer nanosheet aqueous dispersion into 2 mL of the deep eutectic solvent prepared in step (1), mix and stir evenly, and place it in a vacuum oven to dry the water at 60 °C. Finally, the concentration of MXene nanosheets in the mixed solution is 5 mg / mL.

[0125] (3) Add 0.15 g of acrylamide to the mixed solution prepared in step (2). After stirring evenly, add 10 mg of N,N'-methylenebisacrylamide and 11.3 mg of photoinitiator (2,2-dimethoxy-2-phenylacetophenone). After all components are completely dissolved, place the final mixed solution in a petri dish and carry out photoinitiated polymerization under the irradiation of an ultraviolet lamp for 20 min to finally obtain the DES-MXene (DM) eutectic gel lubricant.

[0126] Example 7

[0127] An adaptive lubricating DPM eutectic gel lubricant, the preparation steps are as follows:

[0128] (1) Weigh 2.1 g of choline chloride (ChCl) and 6 g of PEG200. Mix the two and place them in a 25 mL round-bottom flask and seal it. Heat and stir at 60 °C for 2 h (450 rpm). The obtained clear and transparent liquid is the deep eutectic solvent.

[0129] (2) Weigh 0.4 g of polyvinylpyrrolidone (PVP, M w = 8000) solid and add it to 2 mL of the deep eutectic solvent prepared in step (1), and stir for 6 h to obtain a uniformly dispersed solution.

[0130] (3) Add Ti 3 C 2 T x Mix the aqueous dispersion of few-layer MXene nanosheets with the eutectic solvent added with PVP obtained in step (2), stir evenly, and place it in a vacuum oven to dry the water at 60 °C. Finally, the concentration of MXene nanosheets in the mixed solution is 5 mg / mL.

[0131] (4) Add 0.15 g of acrylamide to the mixed solution prepared in step (3). After stirring evenly, add 10 mg of N,N'-methylenebisacrylamide and 11.3 mg of photoinitiator (2,2-dimethoxy-2-phenylacetophenone). After all components are completely dissolved, place the final mixed solution in a petri dish and carry out photoinitiated polymerization under the irradiation of an ultraviolet lamp for 20 min to finally obtain the DES-PVP-MXene (DPM) self-adaptive eutectic gel lubricant.

[0132] Comparative Example 6

[0133] A kind of eutectic gel lubricant, the preparation steps are as follows:

[0134] (1) Weigh 2.1 g of choline chloride (ChCl) and 6 g of PEG200, mix the two and place them in a 25 mL round-bottom flask and seal it. Heat and stir at 60 °C for 2 h (450 rpm), and the obtained clear and transparent liquid is the eutectic solvent.

[0135] (2) Add the aqueous dispersion of Ti 3 C 2 T x few-layer MXene nanosheets to 2 mL of the eutectic solvent prepared in step (1), mix and stir evenly, and place it in a vacuum oven to dry the water at 60 °C. Finally, the concentration of MXene nanosheets in the mixed solution is 5 mg / mL.

[0136] (3) Add 0.15 g of acrylamide to the mixed solution prepared in step (2). After stirring evenly, add 10 mg of N,N'-methylenebisacrylamide and 11.3 mg of photoinitiator (2,2-dimethoxy-2-phenylacetophenone). After all components are completely dissolved, place the final mixed solution in a petri dish and carry out photoinitiated polymerization under the irradiation of an ultraviolet lamp for 20 min to finally obtain the DES-MXene (DM) eutectic gel lubricant.

[0137] Figure 9Photographs of MXene nanosheets dispersed in deep eutectic solvents with the addition of polyvinylpyrrolidone prepared in Example 5, Example 6, and Example 7, and photographs of MXene nanosheets dispersed in deep eutectic solvents prepared in Comparative Example 4, Comparative Example 5, and Comparative Example 6. It can be seen that this method of pre-adding PVP as a stabilizer effectively alleviates the agglomeration of MXene in deep eutectic solvents, and MXene can be evenly dispersed throughout the system. This method is applicable to most ChCl-based DESs and has a certain universality.

[0138] Figure 10 Graph of the change in friction coefficient of the eutectic gel lubricant prepared in Example 5 and Comparative Example 4 over time. The friction coefficients corresponding to Comparative Example 4 and Example 5 are 0.24 and 0.13, respectively. Figure 11 Graph of the change in friction coefficient of the eutectic gel lubricant prepared in Example 6 and Comparative Example 5 over time. The friction coefficients corresponding to Comparative Example 5 and Example 6 are 0.16 and 0.089, respectively. Figure 12 Graph of the change in friction coefficient of the eutectic gel lubricant prepared in Example 7 and Comparative Example 6 over time. The friction coefficients corresponding to Comparative Example 6 and Example 7 are 0.15 and 0.13, respectively. Figures 10 - 12 The friction test conditions are the same as those Figure 4 corresponding thereto. It can be seen that the introduction of PVP can act as a stabilizer to promote the uniform dispersion of MXene in the deep eutectic solvent system and also provides a certain lubricating effect.

[0139] The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A eutectic gel lubricant for adaptive lubrication, characterized in that: The preparation includes the following raw materials: A low eutectic solvent, polyvinyl pyrrolidone, MXene nanosheets, acrylamide, a crosslinker and a photoinitiator; the low eutectic solvent comprises a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is choline chloride, the hydrogen bond donor comprises one or more of ethylene glycol, urea, glycerol and polyethylene glycol, and the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:

2.

2. The eutectic gel lubricant for adaptive lubrication according to claim 1, characterized in that: The low eutectic solvent is obtained by mixing a hydrogen bond acceptor and a hydrogen bond donor under heating conditions, the heating temperature is 50 to 80° C., and the mixing time is 1 to 4 hours.

3. The adaptive lubrication eutectic gel lubricant according to claim 1, characterized in that: The weight average molecular weight of the polyvinyl pyrrolidone is 5800~(1.3×10 6 ).

4. The adaptive lubrication eutectic gel lubricant according to claim 1, characterized in that: The crosslinking agent includes N,N-methylenebisacrylamide; and the photoinitiator includes 2,2-dimethoxy-2-phenylacetophenone.

5. The eutectic gel lubricant for adaptive lubrication according to any one of claims 1 to 3, characterized in that: The usage ratio of the polyvinyl pyrrolidone to the low eutectic solvent is 0.1-0.3 g:1 mL.

6. The adaptive lubrication eutectic gel lubricant according to claim 1 or 2, characterized in that: The usage ratio of the MXene nanosheets to the low eutectic solvent is 4-6 mg:1 mL.

7. The adaptive lubrication eutectic gel lubricant according to claim 1 or 2, characterized in that: The usage ratio of acrylamide to the low eutectic solvent is 0.15-0.23 g:2 mL, the mass ratio of the cross-linking agent to acrylamide is 1:30-1:10, and the mass ratio of the photoinitiator to acrylamide is 1:15-1:

10.

8. The method for preparing the adaptive lubrication eutectic gel lubricant according to any one of claims 1 to 7, characterized in that: The following steps are involved: The low eutectic solvent, polyvinyl pyrrolidone, MXene nanosheets, acrylamide, a crosslinking agent and a photoinitiator are mixed and polymerized under ultraviolet light to obtain the eutectic gel lubricant with adaptive lubrication.

9. The preparation method according to claim 8, characterized in that: The polymerization time is 15 to 40 minutes.

10. Use of the adaptive lubrication eutectic gel lubricant according to any one of claims 1 to 7 or the adaptive lubrication eutectic gel lubricant prepared by the preparation method according to any one of claims 8 to 9 in the field of friction lubrication.

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