High-dispersion-stability surface-functionalized two-dimensional nano material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of lubricating materials, in particular to a high-dispersion-stability surface-functionalized two-dimensional nano material as well as a preparation method and application thereof. According to the preparation method, the two-dimensional nano material is modified by selecting a proper polymer, so that the obtained surface-functionalized two-dimensional nano material has high dispersion stability in lubricating oil and a solvent, and the technical bottleneck that an inorganic nano material is difficult to stably disperse in the solvent and a lubricating medium is solved. Besides, a mechanical ball milling method is adopted for modification, the method has the advantages of being environmentally friendly, simple and easy to prepare on a large scale, and the prepared surface-functionalized two-dimensional nano material can remarkably reduce the friction coefficient and the abrasion loss of lubricating oil as a lubricating oil additive.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricating materials, and particularly relates to a highly dispersible and stable surface-functionalized two-dimensional nanomaterial, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of technology and the increasing prominence of environmental problems, contemporary industry has higher and higher requirements for the lubrication performance of lubricating materials under extremely harsh working conditions such as wide temperature ranges, high and low loads, and high and low speeds. For example, the working temperature of aviation engine lubricating oil usually exceeds 200 °C; high-power diesel locomotives in high-altitude areas in western China need lubricating oil that works at -43 °C to ensure that the engine has good lubrication performance while starting quickly in extremely cold temperatures. In order to meet the demand for high and low temperature, high and low load, and high and low speed lubricating oils for high-end equipment, different types of high-performance synthetic base oils have been developed and industrially applied, including polyalphaolefins (PAO), synthetic ester oils, polyethers (PAG), and perfluoropolyethers (PFPE), etc. However, the types of additives that can meet extremely harsh working conditions, especially anti-friction and anti-wear additives, are very limited, which restricts the development and application of high-performance lubricating oils.

[0003] Currently widely used organic molecular additives containing elements such as sulfur and phosphorus, such as tricresyl phosphate (TCP), zinc dialkyldithiophosphate (ZDDP), and molybdenum dialkyldithiocarbamate (MoDTC), etc., although having excellent anti-friction and anti-wear properties, are prone to decomposition and aging during application, resulting in a significant decline in tribological properties. At the same time, the gases emitted under high-temperature conditions pollute the environment.

[0004] Inorganic two-dimensional materials have been widely used as solid lubricating materials and lubricating oil additives due to their high chemical stability, high thermal stability, excellent tribological properties, low toxicity, and environmental friendliness. For example, during World War I, fighter pilots found that adding MoS 2 to engine oil helped the plane land smoothly. The MoS 2 lubricating oil of Liqui Moly in Germany has a market share of more than 30% in the German market. However, the bottleneck restricting the development of inorganic nano-additives is the unstable dispersion of nano-particles in the lubricating oil medium, which is prone to agglomeration and sedimentation. For example, the MoS 2 friction improver of Liqui Moly has serious deposition due to the unstable dispersion of the MoS 2 additive, and the product needs to be shaken violently before use. These factors result in poor stability, short service life, and poor lubrication reliability of nano-MoS 2 . Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a highly dispersed and stable surface-functionalized two-dimensional nanomaterial, a preparation method thereof and an application thereof.

[0006] In order to achieve the above object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a highly dispersed and stable surface-functionalized two-dimensional nanomaterial, comprising a two-dimensional nanomaterial and a polymer modified on the surface of the two-dimensional nanomaterial; the mass ratio of the two-dimensional nanomaterial to the polymer is 1:3 to 3:1;

[0008] The polymer is a copolymer of monomer A and monomer B or a Pluronic surfactant;

[0009] The monomer A includes one or more of acrylic acid monomers, acrylate monomers, acrylamide monomers, vinyl benzoic acid monomers and 3,4-dihydroxystyrene;

[0010] The monomer B includes methacrylate or acrylate; the ester group in the methacrylate or acrylate is a branched or straight-chain ester group with 4 to 40 carbon atoms.

[0011] Preferably, the acrylic acid monomers include one or more of 2-propylacrylic acid, 2-ethylacrylic acid, β-(acryloyloxy)propionic acid, maleic acid, itaconic acid, vinylacetic acid, 4-pentenoic acid, 5-hexenoic acid, methacrylic acid and acrylic acid;

[0012] The acrylate monomers include at least one of 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 2-hydroxyethyl acrylate, 2,3-dihydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxyphenyl methacrylate and 4-hydroxynaphthalen-1-yl methacrylate;

[0013] The acrylamide monomers include one or more of N-acryloyl(trimethylol)aminomethane, N-(hydroxymethyl)acrylamide, 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole, N-acryloyl(trimethylol)aminomethane, 3-methacryloyldopamine, 3-acrylamido-phenol, 3-acrylamidobenzoic acid, maleic diamide, maleamic acid, 3-acrylamidophenylboronic acid, N-p-hydroxyphenylacrylamide, N-(4-hydroxyphenyl)methacrylamide, N-(3,4-dihydroxyphenethyl)acrylamide, acrylamide, methacrylamide and N-hydroxyethylacrylamide;

[0014] The vinyl benzoic acid monomers include one or more of 4-vinylbenzoic acid, 3-vinylbenzoic acid and 2-vinylbenzoic acid.

[0015] Preferably, the methacrylate includes n-butyl methacrylate, lauryl methacrylate, isooctyl methacrylate, octadecyl methacrylate or dodecyl methacrylate.

[0016] Preferably, the molar amount of the monomer A accounts for 1-40% of the total molar amount of the monomer A and the monomer B.

[0017] Preferably, the weight-average molecular weight of the copolymer of the monomer A and the monomer B is 2000-2000000 g / mol, and the PDI index is 1-10.

[0018] Preferably, the two-dimensional nanomaterial includes BN, Bi 2 Te 3 or MX 2 In the MX 2 , M is Mo, W, Nb, Ta, Re or Ti; X is S, Se or Te.

[0019] The present invention provides a method for preparing the highly dispersible and stable surface-functionalized two-dimensional nanomaterial described in the above solution, including the following steps:

[0020] Ball-milling the polymer and the two-dimensional material raw material to obtain the highly dispersible and stable surface-functionalized two-dimensional nanomaterial; the mass ratio of the two-dimensional material raw material to the polymer is 1:3-3:1.

[0021] Preferably, the rotation speed of the ball-milling is 200-1000 r / min, and the time is 12-60 h.

[0022] The present invention provides an application of the highly dispersible and stable surface-functionalized two-dimensional nanomaterial described in the above solution or the highly dispersible and stable surface-functionalized two-dimensional nanomaterial prepared by the preparation method described in the above solution as a lubricating oil additive.

[0023] Preferably, the lubricating oil is a polar lubricating oil or a non-polar lubricating oil.

[0024] The present invention provides a highly dispersible and stable surface-functionalized two-dimensional nanomaterial, comprising a two-dimensional nanomaterial and a polymer modified on the surface of the two-dimensional nanomaterial; the mass ratio of the two-dimensional nanomaterial to the polymer is 1:3 to 3:1; the polymer is a copolymer of monomer A and monomer B or a Pluronic surfactant; monomer A includes one or more of acrylic acid monomers, acrylate monomers, acrylamide monomers, vinyl benzoic acid monomers, and 3,4-dihydroxystyrene; monomer B includes methacrylate or acrylate; the ester group in the methacrylate or acrylate is a branched or linear ester group with 4 to 40 carbon atoms. By selecting a suitable polymer to modify the two-dimensional nanomaterial, the obtained surface-functionalized two-dimensional nanomaterial has high dispersibility and stability in lubricating oils (whether polar or non-polar).

[0025] The present invention provides a preparation method of the above-mentioned highly dispersible and stable surface-functionalized two-dimensional nanomaterial. Compared with the chemical modification method in the related art, the preparation process is complex, the product is difficult to separate, and the waste liquid and waste gas generated during the preparation process will cause environmental pollution, which is not conducive to large-scale industrial production and application. The present invention uses the mechanical ball milling method for modification, which has the advantages of being green, simple, and easy for large-scale preparation. Moreover, the prepared surface-functionalized two-dimensional nanomaterial has high dispersibility and stability in solvents / base oils, and can meet the lubrication requirements under extremely harsh working conditions such as high and low temperatures, high and low loads, and high and low speeds. Description of the Drawings

[0026] Figure 1 Photographs of MoS 2 -LPDO dispersed in PAO2 standing still for (a) 1 day and (b) 60 days and standing still in n-octane for (c) 1 day and (d) 60 days;

[0027] Figure 2 TEM morphology diagrams of MoS 2 -LPDO prepared by mechanical ball milling at different magnifications;

[0028] Figure 3 XRD spectra of MoS 2 powder and MoS 2 -LPDO after ball milling;

[0029] Figure 4 Curves of friction coefficient varying with time for PAO2 base oil and PAO2 base oil added with 0.5 wt%, 1 wt%, 2 wt%, 3 wt% MoS 2 -LPDO;

[0030] Figure 5For PAO2 base oil and MoS 2 -LPDO's wear scar volume after friction when its addition amounts in PAO2 are 0.5wt%, 1wt%, 2wt%, and 3wt% respectively;

[0031] Figure 6 For 1wt% of MoS 2 -F68 dispersed in (a) trihydroxy complex ester and left standing for 1 day (Ⅰ) and 60 days (Ⅱ), and (b) in castor oil and left standing for 1 day (Ⅰ) and 30 days (Ⅱ); photos

[0032] Figure 7 For 0.1wt% (Ⅰ), 0.05wt% (Ⅱ), and 0.01wt% (Ⅲ) of WS 2 -LBA dispersed in PAO2 and left standing for (a) 1 day and (b) 60 days; photos

[0033] Figure 8 For 0.1wt% (Ⅰ), 0.05wt% (Ⅱ), and 0.01wt% (Ⅲ) of BN-LPDO dispersed in PAO2 and left standing for (a) 1 day and (b) 60 days; photos

[0034] Figure 9 For 0.1wt% (Ⅰ), 0.05wt% (Ⅱ), and 0.01wt% (Ⅲ) of MoS 2 -PMA-LMA dispersed in PAO2 and left standing for (a) 1 day and (b) 60 days; photos

[0035] Figure 10 For 0.1wt% of MoS 2 -PMMA dispersed in PAO2 and left standing for (a) 1 day and (b) 60 minutes; photos Detailed implementation manners

[0036] The present invention provides a highly dispersible and stable surface-functionalized two-dimensional nanomaterial, including a two-dimensional nanomaterial and a polymer modified on the surface of the two-dimensional nanomaterial; the mass ratio of the two-dimensional nanomaterial to the polymer is 1:3 to 3:1.

[0037] In the present invention, unless otherwise specified, the raw materials used are all well-known commercially available products in the art.

[0038] In the present invention, the two-dimensional nanomaterial preferably includes BN, Bi 2 Te 3 or MX 2 wherein M in MX 2 is Mo, W, Nb, Ta, Re or Ti; X is S, Se or Te; in specific embodiments, the two-dimensional nanomaterial can be MoS 2 , WS2 , MoSe 2 , MoTe 2 , TaSe 2 , NbSe 2 or NiTe 2 .

[0039] In the present invention, the polymer is a copolymer of monomer A and monomer B or a Pluronic surfactant.

[0040] In the present invention, the monomer A includes one or more of acrylic acid monomers, acrylate monomers, acrylamide monomers, vinyl benzoic acid monomers, and 3,4-dihydroxystyrene.

[0041] Among them, the acrylic acid monomers preferably include one or more of 2-propylacrylic acid, 2-ethylacrylic acid, β-(acryloyloxy)propionic acid, maleic acid, itaconic acid, vinyl acetic acid, 4-pentenoic acid, 5-hexenoic acid, methacrylic acid, and acrylic acid;

[0042] The acrylate monomers preferably include at least one of 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 2-hydroxyethyl acrylate, 2,3-dihydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxyphenyl methacrylate, and 4-hydroxynaphthalen-1-yl methacrylate;

[0043] The acrylamide monomers preferably include one or more of N-acryloyl(trimethylol)aminomethane, N-(hydroxymethyl)acrylamide, 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole, N-acryloyl(trimethylol)aminomethane, 3-methacryloyldopamine, 3-acrylamido-phenol, 3-acrylamidobenzoic acid, maleic diamide, maleamic acid, 3-acrylamidophenylboronic acid, N-p-hydroxyphenylacrylamide, N-(4-hydroxyphenyl)methacrylamide, N-(3,4-dihydroxyphenethyl)acrylamide, acrylamide, methacrylamide, and N-hydroxyethylacrylamide;

[0044] The vinyl benzoic acid monomers preferably include one or more of 4-vinylbenzoic acid, 3-vinylbenzoic acid, and 2-vinylbenzoic acid.

[0045] In the present invention, the monomer B includes methacrylate or acrylate; the ester group in the methacrylate or acrylate is a branched or straight-chain ester group having 4 to 40 carbon atoms; in a specific embodiment, the number of carbon atoms of the ester group in the methacrylate or acrylate can be 4, 6, 8, 10, 12, 14, 16, 18, 20, 24, 28, 30, 32, 36 or 40; the methacrylate can specifically be n-butyl methacrylate, lauryl methacrylate, isooctyl methacrylate, stearyl methacrylate or dodecyl methacrylate; the acrylate can specifically be dodecyl 2-acrylate, isooctyl acrylate or hexyl acrylate.

[0046] In the present invention, the molar amount of the monomer A preferably accounts for 1 to 40% of the total molar amounts of the monomer A and the monomer B, and can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40% in a specific embodiment.

[0047] In the present invention, the polymer can be a random copolymer or a block copolymer of the monomer A and the monomer B.

[0048] When the polymer is a random copolymer of the monomer A and the monomer B, the preparation method of the copolymer of the monomer A and the monomer B preferably includes: mixing the monomer A, the monomer B, an initiator and a polar organic solvent, and carrying out a copolymerization reaction to obtain the copolymer of the monomer A and the monomer B.

[0049] In the present invention, the initiator preferably includes an azo initiator, and the azo initiator preferably includes azobisisobutyronitrile; the molar amount of the initiator is preferably 0.1 to 0.3% of the total molar amounts of the monomer A and the monomer B, and can be 0.1%, 0.15%, 2% or 3% in a specific embodiment.

[0050] In the present invention, the polar organic solvent preferably includes N,N-dimethylformamide; the present invention has no special requirement for the dosage of the polar organic solvent, and it can ensure the smooth progress of the polymerization reaction.

[0051] In the present invention, the temperature of the copolymerization reaction is preferably 65 to 105 °C, and the time is preferably 6 to 48 h; in a specific embodiment, the temperature of the copolymerization reaction can be 65 °C, 75 °C, 85 °C, 100 °C or 105 °C, and the time of the copolymerization reaction can be 6 h, 10 h, 20 h, 30 h, 40 h or 48 h. In the present invention, the copolymerization reaction is preferably carried out in an oil bath. The present invention preferably first deoxygenates the obtained reaction system after mixing for half an hour in a nitrogen environment, and then places it in an oil bath for copolymerization reaction.

[0052] After completing the copolymerization reaction, the present invention preferably adds methanol to the reaction system to precipitate the polymer. The obtained precipitate is dissolved in N,N-dimethylformamide and then methanol is added again to separate the precipitate, obtaining the copolymer of monomer A and monomer B.

[0053] In the present invention, when the polymer is a block copolymer of monomer A and monomer B, the preparation method of the copolymer of monomer A and monomer B preferably includes: mixing monomer A, a first initiator, a chain transfer agent, and a first polar organic solvent, and carrying out a first polymerization reaction under anhydrous and anaerobic conditions to obtain a prepolymer of monomer A; mixing the prepolymer of monomer A, a second initiator, monomer B, and a second polar organic solvent, and carrying out a second polymerization reaction to obtain a block copolymer of monomer A and monomer B.

[0054] The present invention mixes monomer A, a first initiator, a chain transfer agent, and a first polar organic solvent, and carries out a first polymerization reaction under anhydrous and anaerobic conditions to obtain a prepolymer of monomer A.

[0055] In the present invention, the first initiator preferably includes an azo initiator, and the azo initiator preferably includes azobisisobutyronitrile; the molar amount of the first initiator is preferably 0.1-0.3% of the molar amount of monomer A, and in specific embodiments, it can be 0.1%, 0.15%, 2%, or 3%.

[0056] In the present invention, the chain transfer agent preferably includes 2-cyano-2-propyl dodecyl trithiocarbonate, 4-cyano-4-[(dodecylthio)thiocarbonylthio]valeric acid, or cyanomethyl methyl(phenyl)aminodithiocarbonate; the molar amount of the chain transfer agent is preferably 1-5% of the molar amount of monomer A, and in specific embodiments, it can be 1%, 2%, 3%, 4%, or 5%. In the present invention, the first polar organic solvent preferably includes N,N-dimethylformamide; the present invention has no special requirements for the dosage of the first polar organic solvent, as long as the polymerization reaction can proceed smoothly.

[0057] In the present invention, the temperature of the first polymerization reaction is preferably 65-105°C, and the time is preferably 6-48 h. In specific embodiments, the temperature of the first polymerization reaction can be 65°C, 75°C, 85°C, 95°C, or 105°C, and the time can be 6 h, 10 h, 20 h, 30 h, 40 h, or 48 h.

[0058] After completing the first prepolymerization reaction, the present invention adds methanol to the obtained reaction system to form a precipitate, and separates and dries the obtained precipitate to obtain the prepolymer of monomer A.

[0059] After obtaining the prepolymer of monomer A, the present invention mixes the prepolymer of monomer A, a second initiator, monomer B, and a second polar organic solvent, and performs a second polymerization reaction to obtain a block copolymer of monomer A and monomer B.

[0060] In the present invention, the type of the second initiator is preferably the same as that of the first initiator, which will not be elaborated here. In the present invention, the molar amount of the second initiator is preferably 0.1-0.3% of the total molar amount of monomer A and monomer B, and may be 0.1%, 0.2%, or 0.3% in specific embodiments.

[0061] In the present invention, the second polar organic solvent preferably includes N,N-dimethylformamide; the present invention has no special requirements for the amount of the second polar organic solvent, and it is only necessary to ensure the smooth progress of the polymerization reaction.

[0062] In the present invention, the temperature of the second polymerization reaction is preferably 65-105°C, and the time is preferably 6-48 h; in specific embodiments, the temperature of the second polymerization reaction may be 65°C, 75°C, 85°C, 95°C, or 105°C, and the time may be 6 h, 10 h, 20 h, 30 h, 40 h, or 48 h.

[0063] After completing the second polymerization reaction, the present invention adds methanol to the obtained reaction system to precipitate a solid, and after solid-liquid separation, a block copolymer of monomer A and monomer B is obtained.

[0064] In the present invention, the weight-average molecular weight of the copolymer of monomer A and monomer B (including random copolymer and block copolymer) is preferably 2000-2000000 g / mol, and the PDI index is preferably 1-10; in specific embodiments, the weight-average molecular weight of the copolymer of monomer A and monomer B may be 2000 g / mol, 10000 g / mol, 100000 g / mol, 1000000 g / mol, 1500000 g / mol, or 2000000 g / mol, and the PDI index may be 1, 2, 3, 5, 7, 8, or 10.

[0065] In the present invention, when the polymer is a Pluronic surfactant, the Pluronic surfactant is preferably a commercially available product in the art and has the structure shown in Formula 1:

[0066]

[0067] In the present invention, the Pluronic surfactant preferably includes one or more of Pluronic F series surfactants, Pluronic L series surfactants, and Pluronic P series surfactants; the Pluronic F series surfactants preferably include Pluronic F-68 and / or Pluronic F-127; the Pluronic L series surfactants preferably include Pluronic L-61 and / or Pluronic L-64; the Pluronic P series surfactants preferably include Pluronic P-105 and / or Pluronic P-123.

[0068] In a specific embodiment, the mass ratio of the two-dimensional nanomaterial to the polymer can be 1:3, 2:3, 1:1, 4:3, 5:3, 2:1, 7:3, 8:3, or 3:1.

[0069] By selecting a suitable polymer to modify the two-dimensional nanomaterial, the surface-functionalized two-dimensional nanomaterial obtained in the present invention has high dispersion stability in lubricating oils (whether polar or non-polar) and solvents (whether polar or non-polar), solving the technical bottleneck that inorganic nanomaterials are difficult to stably disperse in solvents and lubricating media.

[0070] The present invention provides a method for preparing the surface-functionalized two-dimensional nanomaterial with high dispersion stability as described in the above solution, comprising the following steps:

[0071] Ball-milling the polymer and the two-dimensional material raw material to obtain the surface-functionalized two-dimensional nanomaterial with high dispersion stability; the mass ratio of the two-dimensional material raw material to the polymer is 1:3 to 3:1.

[0072] In the present invention, the particle size of the two-dimensional material raw material is preferably 100 nm to 5 μm. In a specific embodiment, the particle size of the two-dimensional material raw material can be 100 nm, 200 nm, 500 nm, 800 nm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, or 5 μm.

[0073] In the present invention, the rotation speed of the ball-milling is preferably 200 to 1000 r / min, and the time is preferably 12 to 60 h; in a specific embodiment, the rotation speed of the ball-milling can be 200 r / min, 400 r / min, 500 r / min, 600 r / min, 800 r / min, or 1000 r / min, and the ball-milling time can be 12 h, 20 h, 30 h, 40 h, 50 h, or 60 h.

[0074] In the present invention, the ball milling is preferably carried out under nitrogen protection.

[0075] In the present invention, the ball-to-material ratio of the ball milling is preferably 30:(1 - 90); in specific embodiments, the ball-to-material ratio of the ball milling can be 30:1, 30:5, 30:10, 30:20, 30:30, 30:40, 30:50, 30:60, 30:80 or 30:90.

[0076] In the ball milling process of the present invention, the polymer can effectively intercalate, exfoliate and modify the two-dimensional material, and at the same time, the two-dimensional material changes from a large particle size to a nanoscale, realizing the modification of the polymer.

[0077] Compared with the chemical modification method in the related art, there are problems such as complex preparation process, difficult separation of products, environmental pollution caused by waste liquid and waste gas generated during the preparation process, which is not conducive to large-scale industrial production and application; the present invention uses the mechanical ball milling method for modification, which has the advantages of being green, simple and easy for large-scale preparation, and the prepared surface-functionalized two-dimensional nanomaterials have high dispersion stability and excellent antifriction and antiwear properties.

[0078] The present invention provides the application of the highly dispersible and stable surface-functionalized two-dimensional nanomaterials described in the above solution or the highly dispersible and stable surface-functionalized two-dimensional nanomaterials prepared by the preparation method described in the above solution as a lubricating oil additive.

[0079] In the present invention, the lubricating oil is preferably a polar lubricating oil or a non-polar lubricating oil; there are no special requirements for the specific types of the polar lubricating oil and non-polar lubricating oil of the present invention, and the well-known polar lubricating oil and non-polar lubricating oil in the art can be used. Specifically, the polar lubricating oil can be one or more of trimethylolpropane trioleate (1427), pentaerythritol oleate (1429), polyether synthetic oil (PAG), 5 Ris aviation engine oil and castor oil; the non-polar lubricating oil can be one or more of mineral oil and polyalphaolefin (such as PAO2, PAO4, PAO10).

[0080] The highly dispersible and stable surface-functionalized two-dimensional nanomaterials provided by the present invention as a lubricating oil additive can significantly reduce the friction coefficient and wear amount of the lubricating oil, and can be used to replace the currently widely used traditional lubricating oil additives, such as zinc dialkyldithiophosphate (ZDDP) and molybdenum dialkyldithiocarbamate (MoDTC) and other environmentally unfriendly lubricating additives containing sulfur and phosphorus.

[0081] In the present invention, the addition amount of the highly dispersible and stable surface-functionalized two-dimensional nanomaterials is preferably 0.005 - 10% of the mass of the lubricating oil; in specific embodiments, it can be 0.005%, 0.05%, 0.1%, 1%, 3%, 5%, 7% or 10%.

[0082] The high-dispersion stability surface-functionalized two-dimensional nanomaterials provided by the present invention, their preparation methods and applications will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0083] Example 1

[0084] 3-Methacryloyldopamine and n-butyl methacrylate with a molar ratio of 1:4, azobisisobutyronitrile with a total molar amount of monomers of 0.15%, and an appropriate amount of anhydrous N,N-dimethylformamide were placed in a round-bottom flask. After deoxygenating the reaction system in a nitrogen environment for half an hour, it was heated to 80 °C in an oil bath and reacted for 48 h. After the reaction, methanol was added to the system to precipitate and separate the polymer. The obtained polymer was dissolved in a small amount of N,N-dimethylformamide and then precipitated and separated again to purify the polymer. The obtained polymer was denoted as LPDO. Using gel chromatography PL-GPC50 with chloroform as the mobile phase, the molecular weight and molecular weight distribution of the polymer were characterized. The results showed that the weight-average molecular weight of the prepared LPDO was 28000 g / mol and the PDI was 2.86.

[0085] MoS with a mass ratio of 2:1 2 (1 μm) and LPDO were placed in a ball milling jar. Under nitrogen protection, ball milling was carried out at room temperature at a rotation speed of 500 r / min for 48 h, and the ball-to-material ratio was 30:1, thus obtaining surface-functionalized nano-MoS 2 , denoted as MoS 2 -LPDO.

[0086] Stability test:

[0087] MoS 2 -LPDO was respectively added to PAO2 base oil and n-octane solvent, and the addition amounts were 0.1 wt%, 0.05 wt% and 0.01 wt% respectively. After standing for 60 days, the results are shown in Figure 1 . Figure 1 In, (a) is a photo of 0.1 wt% (Ⅰ), 0.05 wt% (Ⅱ) and 0.01 wt% (Ⅲ) MoS 2 -LPDO dispersed in PAO2 and standing for 1 day, (b) is a photo of 0.1 wt% (Ⅰ), 0.05 wt% (Ⅱ) and 0.01 wt% (Ⅲ) MoS 2 -LPDO dispersed in PAO2 and standing for 60 days, (c) is a photo of 0.1 wt% (Ⅰ), 0.05 wt% (Ⅱ) and 0.01 wt% (Ⅲ) MoS 2 -LPDO dispersed in n-octane and standing for 1 day, (d) is a photo of 0.1 wt% (Ⅰ), 0.05 wt% (Ⅱ) and 0.01 wt% (Ⅲ) MoS 2- Photos of LPDO dispersed in PAO2 and left standing for 60 days.

[0088] MoS with an addition amount of 0.1 wt% 2 - The stable existence time of LPDO in different lubricating base oils is shown in Table 1. In Table 1, PETO is pentaerythritol oleate, which belongs to polar lubricating oil.

[0089] Table 1 Addition of 0.1 wt% of MoS 2 - Stable existence time (days) of LPDO in different lubricating base oils

[0090] PAO2 PETO Trimethylolpropane trioleate Mineral oil Castor oil Polyether synthetic oil (PAG) 60 50 50 60 50 50

[0091] From Table 1 and Figure 1 it can be seen that the dispersion system prepared by the present invention can stably exist for several months.

[0092] Characterization of the morphology and crystallinity of two-dimensional nanomaterials:

[0093] The morphology of nano-MoS 2 -LPDO was characterized by a JEM-1200EX transmission electron microscope (TEM). TEM photos at different magnifications are as Figure 2 shown. Figure 2 are TEM photos of the modified MoS 2 at different magnifications. Figure 2 It shows that the above method can successfully prepare large-particle-size MoS 2 powder into nano-sized MoS 2 .

[0094] The crystal structures of pure MoS 2 and MoS 2 -LPDO nanosheets before and after ball milling were characterized by a XPert PRO PMD X-ray diffractometer (XRD). The results are shown in Figure 3 , where Bulk represents MoS 2 before ball milling, and MoS 2 -AfterMilling represents MoS 2 after ball milling. The ball milling conditions are the same as in Example 1. From Figure 3 it can be seen that the crystallinity of MoS 2 powder obtained by ball milling alone decreases significantly, indicating that its crystal structure is damaged during ball milling. However, the nano-MoS 2 -LPDO prepared by ball milling MoS 2 powder in the presence of polymer LPDO can maintain a good crystal structure. 2

[0095] Tribological property test:

[0096] Using a German Optimol SRV-IV micro tribometer, MoS 2 -LPDO was added to PAO2 at addition amounts of 0 wt%, 0.5 wt%, 1 wt%, 2 wt% and 3 wt% respectively. Friction performance tests were carried out under the conditions of a temperature of 100 °C, a frequency of 25 Hz, an amplitude of 1 mm, a load of 100 N and a time of 30 min. The steel balls used in the test were GCr15 bearing steel with a diameter of 10 mm, and the block used for the lower specimen was a GCr15 steel block with a diameter of 24 mm and a height of 7.9 ± 0.1 mm. The friction coefficient curve is as Figure 4 shown.

[0097] As Figure 4 can be seen, the addition of MoS 2 -LPDO can effectively reduce the friction coefficient of the PAO2 base oil, and the anti-friction effect is the best when the concentration is 0.5 wt%, and the friction coefficient is reduced from 0.2 to 0.11.

[0098] The wear volume of the wear scar on the steel block was characterized using a MicroXAM 3D non-contact surface profiler, and the results are as Figure 5 shown. As Figure 5 can be seen, MoS 2 -LPDO with different dispersion concentrations all showed good anti-wear effects.

[0099] Example 2

[0100] MoS 2 with a mass ratio of 2:1 and Pluronic F-68 were placed in a ball milling jar and ball milled at room temperature for 48 h at a rotation speed of 500 r / min under nitrogen protection, and the ball-to-material ratio was 30:1, thus obtaining surface-modified nano-MoS 2 , denoted as MoS 2 -F68.

[0101] MoS 2 -F68 was added to trihydroxy complex ester and castor oil respectively, and the results of the addition amount of 1 wt% are shown in Figure 6 . Figure 6 In 2 , (a) are the photos of MoS 2 -F68 dispersed in trihydroxy complex ester standing for 1 day (Ⅰ) and standing for 60 days (Ⅱ), and (b) are the photos of MoS 2 -F68 dispersed in castor oil standing for 1 day (Ⅰ) and standing for 30 days (Ⅱ).

[0102] Table 2 Stable existence time (days) of 0.1 wt% MoS

[0103] Trimethylolpropane trioleate PETO Mineral oil Castor oil PAG 60 14 14 30 14

[0104] From Figure 6 and the data in Table 2, it can be seen that MoS 2 -F68 can stably exist in various lubricating oils for two weeks to several months.

[0105] Example 3

[0106] 4-Vinylbenzoic acid and isooctyl methacrylate with a molar ratio of 1:4, azobisisobutyronitrile with a total molar amount of monomers of 0.15%, and an appropriate amount of anhydrous N,N-dimethylformamide were placed in a round-bottom flask. After deoxygenating the reaction system in a nitrogen environment for half an hour, it was heated to 80 °C in an oil bath and reacted for 48 h. After the reaction, methanol was added to the system to precipitate and separate the polymer. The obtained polymer was dissolved in a small amount of N,N-dimethylformamide and then precipitated and separated again to purify the polymer. The obtained polymer was denoted as LBA.

[0107] WS with a mass ratio of 2:1 2 (12,500 mesh) and LBA were placed in a ball mill jar. Under nitrogen protection, ball milling was carried out at room temperature at a rotation speed of 500 r / min for 48 h, and the ball-to-material ratio was 30:1, thus obtaining surface-functionalized nano-WS 2 , denoted as WS 2 -LBA.

[0108] Stability test:

[0109] WS 2 -LBA was respectively added to the PAO2 base oil, and the addition amounts were 0.1 wt%, 0.05 wt%, and 0.01 wt% respectively. After standing for 60 days, the results are shown in Figure 7 . Figure 7 In, (a) is a photo of 0.1 wt% (Ⅰ), 0.05 wt% (Ⅱ), and 0.01 wt% (Ⅲ) WS 2 -LBA dispersed in PAO2 and standing for 1 day, and (b) is a photo of 0.1 wt% (Ⅰ), 0.05 wt% (Ⅱ), and 0.01 wt% (Ⅲ) WS 2 -LPDO dispersed in PAO2 and standing for 60 days, showing that WS 2 -LPDO can be uniformly dispersed in PAO2 and can be stably dispersed in PAO2 for two months.

[0110] Example 4

[0111] N-hydroxyethyl acrylamide and lauryl methacrylate with a molar ratio of 1:4, azobisisobutyronitrile with a total molar amount of monomers of 0.15%, and an appropriate amount of anhydrous N,N-dimethylformamide were placed in a round-bottom flask. After deoxygenating the reaction system in a nitrogen environment for half an hour, it was heated to 80 °C in an oil bath and reacted for 48 h. After the reaction, methanol was added to the system to precipitate and separate the polymer. The obtained polymer was dissolved in a small amount of N,N-dimethylformamide and then precipitated and separated again to purify the polymer. The obtained polymer was denoted as LNO.

[0112] BN (12,500 mesh) and LNO with a mass ratio of 2:1 were placed in a ball mill jar. Under nitrogen protection, ball milling was carried out at room temperature at a rotation speed of 500 r / min for 48 h, and the ball-to-material ratio was 30 / 1, thus obtaining surface-functionalized nano-BN, denoted as BN-LNO.

[0113] Stability test:

[0114] BN-LNO was added to PAO2 base oil respectively, and the addition amounts were 0.1 wt%, 0.05 wt%, and 0.01 wt% respectively. After standing for 60 days, the results are shown in Figure 8 . Figure 8 In it, (a) are the photos of 0.1 wt% (Ⅰ), 0.05 wt% (Ⅱ), and 0.01 wt% (Ⅲ) BN-LPDO dispersed in PAO2 after standing for 1 day, and (b) are the photos of 0.1 wt% (Ⅰ), 0.05 wt% (Ⅱ), and 0.01 wt% (Ⅲ) BN-LPDO dispersed in PAO2 after standing for 60 days, showing that WS 2 -LPDO can be evenly dispersed in PAO2 and can be stably dispersed in PAO2 for two months.

[0115] Example 5

[0116] 1 g of methacrylic acid, 0.08 g of azobisisobutyronitrile, 0.05 g of 2-cyano-2-propyl dodecyl trithiocarbonate, and an appropriate amount of anhydrous N,N-dimethylformamide were placed in a round-bottom flask. After deoxygenating the reaction system in a nitrogen environment for half an hour, it was heated to 80 °C in an oil bath and reacted for 48 h. After the reaction, methanol was added to the system for precipitation separation and drying, denoted as a macroinitiator. The above macroinitiator, 10 g of lauryl methacrylate, 0.08 g of azobisisobutyronitrile, and an appropriate amount of anhydrous N,N-dimethylformamide were placed in a round-bottom flask. After deoxygenating the reaction system in a nitrogen environment for half an hour, it was heated to 80 °C in an oil bath and reacted for 48 h. After the reaction, methanol was added to the system for precipitation separation, and the obtained block polymer was denoted as PMA-LMA

[0117] MoS with a mass ratio of 2:1 2(12,500 mesh) and PMA-LMA were placed in a ball mill jar and ball milled at room temperature for 48 h at a rotation speed of 500 r / min under nitrogen protection, with a ball-to-material ratio of 30:1, to obtain surface-functionalized nano-MoS 2 , denoted as MoS 2 -PMA-LMA.

[0118] MoS 2 -PMA-LMA was added to PAO2 base oil at addition amounts of 0.1 wt%, 0.05 wt%, and 0.01 wt%, respectively, and left standing for 60 days. The results are shown in Figure 9 . Figure 9 . In 2 , (a) are photos of 0.1 wt% (Ⅰ), 0.05 wt% (Ⅱ), and 0.01 wt% (Ⅲ) of MoS2-PMMA dispersed in PAO2 after standing for 1 minute, and (b) are photos of 0.1 wt% (Ⅰ), 0.05 wt% (Ⅱ), and 0.01 wt% (Ⅲ) of MoS

[0119] Comparative Example 1

[0120] MoS 2 (12,500 mesh) and polymethyl methacrylate (PMMA, purchased from Macklin, with a molecular weight of 35,000) were placed in a ball mill jar and ball milled at room temperature for 48 h at a rotation speed of 500 r / min under nitrogen protection, with a ball-to-material ratio of 30:1, to obtain surface-functionalized nano-MoS 2 , denoted as MoS 2 -PMMA.

[0121] Stability test:

[0122] MoS 2 -PMMA was added to PAO2 base oil at an addition amount of 0.1 wt% and left standing for 60 minutes. The results are shown in Figure 9 . Figure 9 . In 2 , (a) is a photo of 0.1 wt% of MoS 2 -PMMA dispersed in PAO2 after standing for 1 minute, and (b) is a photo of 0.1 wt% of MoS Figure 9 It can be seen that MoS 2 -PMMA is difficult to stably disperse in PAO2 base oil for a long time and sedimentation occurs only after 60 minutes.

[0123] Comparative Example 2

[0124] MoS 2(12,500 mesh) and low-density polyethylene powder were placed in a ball milling jar and ball milled at a rotation speed of 500 r / min for 48 h at room temperature under nitrogen protection, with a ball-to-material ratio of 30:1, thus obtaining surface-functionalized nano-MoS 2 , denoted as MoS 2 -PE.

[0125] Stability test:

[0126] MoS 2 -PE was added to PAO2 base oil at an addition amount of 0.1 wt%. After ultrasonic treatment for 60 minutes and standing for 60 minutes, there was obvious precipitation at the bottom.

[0127] Comparative Example 3

[0128] MoS 2 (12,500 mesh) and butyl methacrylate with a mass ratio of 2:1 were placed in a ball milling jar and ball milled at a rotation speed of 500 r / min for 48 h at room temperature under nitrogen protection, with a ball-to-material ratio of 30:1, thus obtaining surface-functionalized nano-MoS 2 , denoted as MoS 2 -BuMA.

[0129] Stability test:

[0130] MoS 2 -BuMA was added to PAO2 base oil at an addition amount of 0.1 wt%. MoS 2 -BuMA was added to PAO2 base oil at an addition amount of 0.1 wt%. After ultrasonic treatment for 60 minutes and standing for 60 minutes, the solvent was significantly stratified and there was precipitation at the bottom.

[0131] Comparative Example 4

[0132] MoS 2 (12,500 mesh) and methacrylic acid with a mass ratio of 2:1 were placed in a ball milling jar and ball milled at a rotation speed of 500 r / min for 48 h at room temperature under nitrogen protection, with a ball-to-material ratio of 30:1, thus obtaining surface-functionalized nano-MoS 2 , denoted as MoS 2 -MMA.

[0133] Stability test:

[0134] MoS 2 -MMA was added to PAO2 base oil at an addition amount of 0.1 wt%. MoS 2 -MMA was added to PAO2 base oil at an addition amount of 0.1 wt%. After ultrasonic treatment for 60 minutes and standing for 60 minutes, the solvent was significantly stratified and there was precipitation at the bottom.

[0135] Comparative Example 5

[0136] Put MoS₂ with a mass ratio of 2:1 2 (12,500 mesh) and 2-hydroxyethyl methacrylate into a ball milling tank, and ball mill at room temperature for 48 h at a rotation speed of 500 r / min under nitrogen protection, with a ball-to-material ratio of 30:1, to obtain surface-functionalized nano-MoS₂ 2 , denoted as MoS₂ 2 -MA-OH.

[0137] Stability test:

[0138] Add MoS₂ 2 -MA-OH to PAO2 base oil with an addition amount of 0.1 wt%, add MoS₂ 2 -MA-OH to PAO2 base oil with an addition amount of 0.1 wt%, ultrasonicate for 60 minutes, and after standing for 60 minutes, the solvent has obvious stratification and precipitation at the bottom.

[0139] Comparative Example 6

[0140] Put MoS₂ with a mass ratio of 2:1 2 (12,500 mesh) and polystyrene resin into a ball milling tank, and ball mill at room temperature for 48 h at a rotation speed of 500 r / min under nitrogen protection, with a ball-to-material ratio of 30:1, to obtain surface-functionalized nano-MoS₂ 2 , denoted as MoS₂ 2 -PS.

[0141] Stability test:

[0142] Add MoS₂ 2 -PS to PAO2 base oil with an addition amount of 0.1 wt%, add MoS₂ 2 -PS to PAO2 base oil with an addition amount of 0.1 wt%, ultrasonicate for 60 minutes, and after standing for 60 minutes, the solvent has obvious stratification and precipitation at the bottom.

[0143] The above are only the preferred embodiments of 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 surface functionalized two-dimensional nanomaterial with high dispersion stability, characterized in that: It comprises a two-dimensional nanomaterial and a polymer modified on the surface of the two-dimensional nanomaterial; the mass ratio of the two-dimensional nanomaterial to the polymer is 1:3 to 3:1; The polymer is a copolymer of monomer A and monomer B or a Pluronic surfactant; The monomer A includes one or more of olefin monomers, acrylate monomers, acrylamide monomers, vinylbenzoic acid monomers and 3,4-dihydroxystyrene; The monomer B includes methacrylate or acrylate; the ester group in the methacrylate or acrylate is a branched or linear ester group having 4 to 40 carbon atoms.

2. The surface functionalized two-dimensional nanomaterial with high dispersion stability according to claim 1, characterized in that: The olefinic monomers include one or more of 2-propyl acrylic acid, 2-ethyl acrylic acid, β-(acryloyloxy) propionic acid, maleic acid, itaconic acid, vinyl acetic acid, 4-pentenoic acid, 5-hexenoic acid, methacrylic acid and acrylic acid; The acrylic acid ester monomer includes at least one of 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, hydroxyethyl acrylate, 2,3-dihydroxypropyl acrylate, 4-hydroxybutyl acrylate, hydroxyethyl methacrylate, 4-hydroxyphenyl methacrylate and 4-hydroxynaphthalene-1-methacrylate; The acrylamide monomers include one or more of N-acryloyl (trihydroxymethyl) aminomethane, N-(hydroxymethyl) acrylamide, 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl] phenyl]-2H-benzotriazole, N-acryloyl (trihydroxymethyl) aminomethane, 3-methacryloyl dopamine, 3-acrylamide-phenol, 3-acrylamide benzoic acid, maleic acid diamine, maleamic acid, 3-acrylamidophenylboric acid, N-p-hydroxyphenyl acrylamide, N-(4-hydroxyphenyl) methacrylamide, N-(3,4-dihydroxyphenylethyl) acrylamide, acrylamide, methacrylamide and N-hydroxyethyl acrylamide; The vinylbenzoic acid monomer includes one or more of 4-vinylbenzoic acid, 3-vinylbenzoic acid and 2-vinylbenzoic acid.

3. The surface functionalized two-dimensional nanomaterial with high dispersion stability according to claim 1, characterized in that: The methacrylate includes n-butyl methacrylate, lauryl methacrylate, isooctyl methacrylate, octadecyl methacrylate or dodecyl methacrylate.

4. The surface functionalized two-dimensional nanomaterial with high dispersion stability according to claim 1 or 2, characterized in that: The molar amount of the monomer A accounts for 1 to 40% of the total molar amount of the monomer A and the monomer B.

5. The surface functionalized two-dimensional nanomaterial with high dispersion stability according to claim 1 or 2, characterized in that: The weight average molecular weight of the copolymer of monomer A and monomer B is 2000-2000000 g / mol, and the PDI index is 1-10.

6. The surface functionalized two-dimensional nanomaterial with high dispersion stability according to claim 1, characterized in that: The two-dimensional nanomaterial includes BN, Bi2Te3 or MX2, wherein in the MX2, M is Mo, W, Nb, Ta, Re or Ti; and X is S, Se or Te.

7. The method for preparing the surface functionalized two-dimensional nanomaterial with high dispersion stability according to any one of claims 1 to 6, characterized in that: The following steps are involved: The polymer and the two-dimensional material raw material are ball-milled to obtain the surface functionalized two-dimensional nanomaterial with high dispersion stability; the mass ratio of the two-dimensional material raw material to the polymer is 1:3 to 3:

1.

8. The preparation method according to claim 7, characterized in that: The ball mill has a rotation speed of 200 to 1000 r / min and a milling time of 12 to 60 hours.

9. Use of the surface functionalized two-dimensional nanomaterial with high dispersion stability described in any one of claims 1 to 6 or the surface functionalized two-dimensional nanomaterial with high dispersion stability prepared by the preparation method described in any one of claims 7 to 8 as a lubricating oil additive.

10. The use according to claim 9, characterized in that: The lubricating oil is polar lubricating oil or non-polar lubricating oil.

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