Molybdenum disulfide coating and preparation method thereof

Abstract

The invention discloses a molybdenum disulfide coating and a preparation method thereof.The preparation method comprises the steps that molybdenum disulfide nanosheets are subjected to plasma treatment and dissolved in an anhydrous solvent I, a silane coupling agent, carboxyl-terminated fluorine-containing polyether sulfone, N, N '-dicyclohexylcarbodiimide and 4-dimethylaminopyridine are added and stirred to be dissolved, the pH is adjusted to be 5-6, and the molybdenum disulfide coating is obtained; carrying out microwave treatment to obtain a fluorine polyarylether sulfone-molybdenum disulfide modified compound; the preparation method comprises the following steps: respectively preparing an oil phase and a water phase, carrying out mixed emulsification treatment, heating, adding a chain extender and a catalyst, and carrying out polymerization reaction to obtain microcapsules; the modified compound is dissolved in an anhydrous solvent II, graphene quantum dots are added, after ultrasonic treatment, microcapsules, a flame retardant and pentaerythritol tetra-3-mercaptopropionate are added, and after stirring and curing, the molybdenum disulfide coating is obtained. Therefore, the molybdenum disulfide coating has triple functions of super lubrication, self-repairing and flame retardance, and is excellent in performance, economical, simple and convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of solid lubricating coatings, and in particular to a molybdenum disulfide coating and a preparation method thereof. Background Art

[0002] Wear caused by friction is a common phenomenon in daily life and all areas of the national economy. Wear is one of the main causes of failure of mechanical parts and has a great impact on the life and reliability of mechanical parts. Therefore, solid lubricating coatings are often sprayed on the surface of mechanical parts to provide surface protection in extreme environments, help mechanical parts withstand the influence of these harsh conditions, and extend their service life.

[0003] Solid lubricant coating technology combines solid lubricants such as molybdenum disulfide, graphite, and polytetrafluoroethylene with binders such as resins and polyimides. The coating is then applied to mechanical components through spraying, dipping, brushing, or vapor deposition to form a thin film with friction-reducing, wear-resistant, and high-temperature resistant properties. Commonly used solid lubricant coatings include molybdenum disulfide (MoS2), graphite, polytetrafluoroethylene (PTFE), and tungsten disulfide (Tungsten Disulfide). However, graphite-based coatings are susceptible to oxidation failure at high temperatures (>400°C), polytetrafluoroethylene (PTFE) coatings have low load-bearing capacity, and tungsten disulfide coatings are thicker and more expensive. Molybdenum disulfide coatings, on the other hand, offer extremely low friction coefficients, superior lubricity, high temperature resistance, stability to acids, alkalis, and organic solvents, and excellent mechanical and electrical properties, making them a key development area for solid lubricant coatings. However, at temperatures exceeding 400°C, MoS2 oxidizes, gradually losing its lubricating properties. Furthermore, in the presence of water, the friction coefficient of MoS2 increases, weakening its friction-reducing effect and making it difficult to meet practical application requirements.

[0004] Currently, researchers have mostly improved the friction and wear properties of molybdenum disulfide in atmospheric environments by adding metallic elements or doping it to form composite coatings. However, these methods are costly, require expensive equipment, and involve complex operating procedures. Therefore, developing a new, economical and simple molybdenum disulfide coating material that optimizes its various properties, effectively handles harsh operating environments, and extends the lifespan of molybdenum disulfide coatings is a pressing technical challenge for those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a molybdenum disulfide coating and a preparation method thereof. The molybdenum disulfide coating material can effectively combine the advantageous properties of carboxyl-terminated fluorinated polyarylethersulfone and polyurethane resin, enhance the high temperature resistance, chemical stability, mechanical properties and flame retardancy of the molybdenum disulfide coating material, optimize its surface properties, and realize self-repair of cracks in the molybdenum disulfide coating material by constructing polyurethane microcapsules, effectively reducing the negative effects of various harsh environments and extending the service life of the molybdenum disulfide coating.

[0006] In order to achieve the above object, the present invention provides a method for preparing a molybdenum disulfide coating, comprising the following steps: S1, plasma-treating molybdenum disulfide nanosheets and dissolving them in anhydrous solvent I, adding a silane coupling agent, carboxyl-terminated fluorinated polyarylethersulfone, N,N'-dicyclohexylcarbodiimide, and 4-dimethylaminopyridine, stirring and dissolving, adjusting the pH to 5-6, and microwave-treating to obtain a fluorinated polyarylethersulfone-molybdenum disulfide modified composite; S2, separately preparing an oil phase and an aqueous phase, mixing and emulsifying them, raising the temperature and adding a chain extender and a catalyst to carry out a polymerization reaction to obtain microcapsules; S3. Dissolve the modified composite in anhydrous solvent II, add graphene quantum dots, and after ultrasonic treatment, add microcapsules, flame retardant, and pentaerythritol tetrakis-3-mercaptopropionate respectively, stir and solidify to obtain a molybdenum disulfide coating.

[0007] In some embodiments of the present invention, in step S1, the thickness of the molybdenum disulfide nanosheets is less than 5 nm and the diameter is 1-2 μm, the anhydrous solvent I is N-methylpyrrolidone with a purity of ≥99.99%, the silane coupling agent is one or more of silane coupling agent KH-550, silane coupling agent A-1120 and silane coupling agent A-1100, the mass ratio of the molybdenum disulfide nanosheets to the silane coupling agent is 4-7:1-3, and the amount of the anhydrous solvent I is 10-15% of the mass of the polyurethane prepolymer.

[0008] In some embodiments of the present invention, step S1 includes: S1.1. Weigh molybdenum disulfide nanosheets, spread them evenly on a quartz carrier, and after vacuum drying, place them in a plasma chamber. Flow 99.99% pure argon into the chamber at a flow rate of 20-25 sccm, maintaining a dynamic pressure of 0.1-0.3 mbar. Turn on the RF power supply, set the power to 100 W, and the frequency to 13.56 MHz. Ensure that the chamber wall temperature is ≤40°C. Continue the treatment for 5-10 minutes to obtain plasma-treated molybdenum disulfide. S1.2. Slowly add the plasma-treated MoS2 nanosheets to anhydrous solvent I. After ultrasonic dispersion, add a silane coupling agent and magnetically stir at 300-500 rpm for 10-15 minutes to fully dissolve the modified MoS2 nanosheets. S1.3. Add carboxyl-terminated fluorinated polyarylethersulfone with a fluorine content of 12% in batches, stir in a water bath at 60°C until completely dissolved, then add N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine in sequence, stir for 15-20 minutes, add 2 drops of glacial acetic acid, adjust the pH of the reaction system to 5-6, place in a microwave reactor, and react at 75-85°C for 30-45 minutes at a power of 300-350W and a pulse mode of 10s on / 5s off. Then pour into 200 mL of ethanol for precipitation, and obtain a fluorinated polyarylethersulfone-molybdenum disulfide modified composite after high-speed centrifugation.

[0009] In some embodiments of the present invention, in step S2, the fluorine-containing polyol is one or more of perfluoropolyether diol, fluorinated polycarbonate diol and fluorinated polyester diol, the diisocyanate is one or more of toluene diisocyanate, diphenylmethane diisocyanate and isophorone diisocyanate, the surfactant is sodium lauryl sulfate, the chain extender is one or more of ethylenediamine, 1,4-butanediol and adipic acid dihydrazide, and the catalyst is stannous octoate.

[0010] In some embodiments of the present invention, in step S2, the amount of dimethyl disulfide is 30-35% of the mass of the prepolymer, the mass ratio of the fluorinated polyol to the diisocyanate is 2-7:1-3, the amount of the surfactant is 0.5-1% of the mass of the aqueous phase, and the amount of the chain extender is 2-5% of the mass of the prepolymer.

[0011] In some embodiments of the present invention, step S2 includes: S2.1. Add dimethyl disulfide and fluorinated polyol to a reaction vessel, stir magnetically at 200-300 rpm for 15-20 min, then slowly add diisocyanate dropwise and stir on ice for 30-40 min to form a prepolymer to obtain an oil phase. Simultaneously, add deionized water and surfactant to another reaction vessel, stir in a 40°C water bath until dissolved, to obtain an aqueous phase. S2.2. The oil phase solution is dropped into the aqueous phase at a rate of 0.5 ml / min. At the same time, high-speed shear emulsification is performed at 8000-10000 rpm for 10-15 min to form an O / W emulsion. The temperature is raised to 60-75°C, and a chain extender and a catalyst are added. After reacting under nitrogen protection for 6-8 hours, the emulsion is cooled to room temperature and centrifuged at 5000-6000 rpm for 3-5 minutes. The emulsion is washed with an ethanol / water mixture with a volume ratio of 1:1 and passed through a 400-mesh sieve to obtain microcapsules with a particle size distribution of 2-5 μm.

[0012] In some embodiments of the present invention, in step S3, the anhydrous solvent II is N-methylpyrrolidone with a purity of ≥99.8%, the flame retardant is a DOPO derivative FR-102 flame retardant, the mass ratio of the modified composite to the graphene quantum dots is 5-9:1-3, the amount of the anhydrous solvent II is 60-70% of the mass of the molybdenum disulfide coating, the mass ratio of the microcapsules to the pentaerythritol tetrakis-3-mercaptopropionate is 4-6:1-2, and the amount of the flame retardant is 2-5% of the mass of the molybdenum disulfide coating.

[0013] In some embodiments of the present invention, step S3 includes: S3.1. Add the modified composite to anhydrous solvent II and magnetically stir until completely dissolved. Then, add graphene quantum dots with a diameter of 3 to 5 nm and ultrasonically treat at 40 kHz and 300 W for 25 to 30 minutes to obtain a three-dimensional lubricated network. S3.2. Slowly add microcapsules and magnetically stir at a stirring speed of 100-150 rpm for 40-60 minutes. Add flame retardants in batches, stirring for 5 minutes after each addition of 1 g. Then inject pentaerythritol tetrakis-3-mercaptopropionate and continue stirring until the viscosity of the system is stable. After pre-curing in an oven at 70-80°C for 1-2 hours, increase the temperature in steps of 2°C / min to 150-200°C, keep warm for 1-2 hours, and then naturally cool to 80°C and maintain for 1 hour to obtain a cured molybdenum disulfide coating.

[0014] The present invention provides a molybdenum disulfide coating, which is prepared by the above-mentioned preparation method of the molybdenum disulfide coating, comprising molybdenum disulfide nanosheets, anhydrous solvent I, a silane coupling agent, carboxyl-terminated fluorinated polyarylethersulfone, N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine, dimethyl disulfide, fluorinated polyol, diisocyanate, surfactant, chain extender, catalyst, anhydrous solvent II, graphene quantum dots, flame retardant, and pentaerythritol tetrakis-3-mercaptopropionate; wherein, The molybdenum disulfide nanosheets serve as a core lubricating phase, providing an ultra-low friction surface through a vertically oriented layered structure, thereby enhancing the wear resistance of the molybdenum disulfide coating; The silane coupling agent bridges the molybdenum disulfide and the fluorinated polyarylethersulfone through a covalent bond, thereby improving the inorganic-organic interface bonding strength of the molybdenum disulfide coating and preventing the molybdenum disulfide nanosheets from peeling off; The carboxyl-terminated fluorinated polyarylethersulfone is used to provide the molybdenum disulfide nanosheets with high-temperature resistant active groups such as sulfone groups, and to construct a low surface energy interface with the fluorine segments, thereby improving the high-temperature resistance and chemical stability of the molybdenum disulfide coating. The N,N'-dicyclohexylcarbodiimide is used to catalyze the amidation reaction between the carboxyl group of the carboxyl-terminated fluorinated polyarylethersulfone and silylated molybdenum disulfide, thereby increasing the grafting rate and preventing the side reaction from consuming the active group. The 4-dimethylaminopyridine is used as a proton transfer catalyst to accelerate the conversion efficiency of the N,N'-dicyclohexylcarbodiimide intermediate, effectively shortening the microwave-assisted grafting reaction time of the molybdenum disulfide coating; The dimethyl disulfide is used to provide a core material for polyurethane microcapsules, and the coating self-repair is achieved through a dynamic sulfur exchange reaction, thereby enhancing the crack self-repair function of the molybdenum disulfide coating. The fluorinated polyol is used to introduce fluorinated segments into the polyurethane microcapsule shell, thereby enhancing compatibility with the carboxyl-terminated fluorinated polyarylethersulfone matrix and preventing the polyurethane microcapsules from agglomerating. The diisocyanate is used to react to form a polyurethane microcapsule shell, thereby improving the dimethyl disulfide release rate of the molybdenum disulfide coating; The chain extender is used to adjust the mechanical properties of the polyurethane shell and improve the hardness and toughness of the molybdenum disulfide coating; The graphene quantum dots are used to fill the interlayer defects of the molybdenum disulfide, construct a three-dimensional heat conduction-lubrication network, and improve the in-plane thermal conductivity and wear resistance of the molybdenum disulfide coating; The pentaerythritol tetrakis-3-mercaptopropionate is used to provide a high-density thiol group in the polyurethane prepolymer, which undergoes a reversible sulfur exchange reaction with dimethyl disulfide, thereby improving the indoor self-repair rate of the molybdenum disulfide coating.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses a silane coupling agent to modify the plasma-pretreated molybdenum disulfide nanosheets. The silanol generated by the hydrolysis of the silane coupling agent undergoes dehydration condensation with the hydroxyl groups on the surface of the molybdenum disulfide to generate stable covalent bonds, and introduces amino functional groups to the surface of the molybdenum disulfide. The molybdenum disulfide nanosheets are plasma-treated, and argon ions bombard the surface of the molybdenum disulfide under the acceleration of the radio frequency electric field, stripping off the weakly bound sulfur atoms. The generated sulfur vacancies can be used as anchoring points for the subsequent silane coupling agent. The high-energy electrons in the plasma will break the Mo-S bond, generating dangling bonds, and forming active molybdenum sites on the surface, which can chemically bond with the silanol in the silane coupling agent, effectively improving the grafting rate of molybdenum disulfide and the silane coupling agent, ensuring the amount of amino groups on the surface of the molybdenum disulfide, and laying the foundation for the subsequent covalent grafting with the carboxyl-terminated fluorinated polyaryl ether sulfone. At the same time, carboxyl-terminated fluorinated polyaryl ether sulfone is used to modify molybdenum disulfide nanosheets. The carboxyl group at the end of the carboxyl-terminated fluorinated polyaryl ether sulfone molecular chain undergoes a condensation reaction with the amino group on the surface of the modified molybdenum disulfide to form a stable amide bond. Through the "bridging" effect of the silane coupling agent, a covalent connection is established between molybdenum disulfide and the carboxyl-terminated fluorinated polyaryl ether sulfone. This double chemical bonding significantly improves the interfacial compatibility between inorganic nanomaterials and organic polymers. At the same time, the introduction of the high-temperature resistant active group sulfonyl and aromatic ring structure of the fluorinated polyaryl ether sulfone improves the high-temperature resistance of the molybdenum disulfide coating, and synergistically with the fluorine segment to give the molybdenum disulfide coating chemical stability and low surface energy.

[0016] (2) The present invention adopts the microcapsule technology of polyurethane-wrapped dimethyl disulfide, utilizes the reaction of fluorinated polyol and diisocyanate to form a polyurethane shell, introduces fluorinated chain segments, and generates fluorine-fluorine interaction with carboxyl-terminated fluoropolyaryl ether sulfone, thereby enhancing the interfacial bonding between the microcapsule and the substrate. With dimethyl disulfide as the inner core, when microcracks are generated in the coating, the microcapsule ruptures and releases dimethyl disulfide. The disulfide bonds in dimethyl disulfide can undergo a reversible sulfur exchange reaction with the thiol groups in the polyurethane, thereby achieving efficient self-repair of the cracks. At the same time, the carbamate groups in the polyurethane form hydrogen bonds with the sulfone groups of the carboxyl-terminated fluoropolyaryl ether sulfone, further improving the peel strength between the microcapsule and the substrate.

[0017] (3) The present invention uses a fluoropolyaryl ether sulfone-molybdenum disulfide modified composite, graphene quantum dots, polyurethane microcapsules, flame retardants, and pentaerythritol tetramercaptopropionate to first cure at low temperature, and then perform high-temperature cross-linking and curing by gradient heating to form a molybdenum disulfide coating. Vertically oriented molybdenum disulfide nanosheets and graphene quantum dots are used to construct a three-dimensional lubricating network through π-π stacking and hydrogen bonding, which effectively reduces the friction coefficient of the molybdenum disulfide coating. At the same time, the thiol group of pentaerythritol tetramercaptopropionate and the isocyanate group of the polyurethane prepolymer undergo nucleophilic addition reaction to form a thiocarbamate bond, thereby improving the mechanical strength of the molybdenum disulfide coating, and introducing thiol groups on the surface of the polyurethane shell to improve the sulfur exchange repair efficiency of dimethyl disulfide. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] The present invention provides a method for preparing a molybdenum disulfide coating, comprising the following steps: S1. Plasma-treat molybdenum disulfide nanosheets and dissolve them in anhydrous solvent I. Add a silane coupling agent, carboxyl-terminated fluorinated poly(aryl ether sulfone), N,N'-dicyclohexylcarbodiimide, and 4-dimethylaminopyridine. After stirring and dissolving, adjust the pH to 5-6 and microwave-treat them to obtain a fluorinated poly(aryl ether sulfone)-molybdenum disulfide modified composite.

[0020] In step S1, the thickness of the molybdenum disulfide nanosheets is less than 5 nm and the diameter is 1-2 μm. The anhydrous solvent I is N-methylpyrrolidone with a purity of ≥99.99%. The silane coupling agent is one or more of silane coupling agent KH-550, silane coupling agent A-1120, and silane coupling agent A-1100. The mass ratio of the molybdenum disulfide nanosheets to the silane coupling agent is 4-7:1-3. The amount of anhydrous solvent I is 10-15% of the mass of the polyurethane prepolymer.

[0021] Step S1 includes: S1.1. Weigh molybdenum disulfide nanosheets, spread them evenly on a quartz carrier, place them in a vacuum oven at 75~80℃ and dry them for 2~3h, then place them in a plasma chamber. Let argon gas with a purity of 99.99% flow into the chamber, control the flow rate at 20~25sccm, maintain the dynamic pressure at 0.1~0.3mbar, turn on the RF power supply, set the power to 100W, the frequency to 13.56MHz, ensure that the chamber wall temperature is ≤40℃, and continue the treatment for 5~10min to obtain plasma-treated molybdenum disulfide.

[0022] Vacuum drying effectively removes surface-adsorbed water and organic impurities from the MoS2 nanosheets. Controlling the drying temperature between 75 and 80°C, which is below the oxidation threshold of MoS2, removes only physically adsorbed water and prevents structural damage. Drying at this temperature for 2 to 3 hours ensures the evaporation of deep-seated moisture, preventing water vapor interference during subsequent plasma treatment. 99.99% pure argon is introduced into the plasma chamber. This inert gas prevents MoS2 oxidation while also bombarding the MoS2 with argon ions, effectively activating the MoS2 surface. Controlling the gas flow rate within the plasma chamber between 20 and 25 sccm balances plasma density and gas consumption, maintaining a stable plasma concentration within the chamber and avoiding uneven treatment due to low gas flow rates and gas waste due to high gas flow rates. Dynamic pressure is controlled between 0.1 and 0.3 mbar to ensure plasma uniformity and prevent excessive pressure from reducing ion energy.

[0023] Controlling the RF power at around 100W balances surface activation and structural integrity, preventing structural damage to the MoS2 caused by excessive power. The frequency, controlled at 13.56MHz, the industry-standard RF frequency, ensures stable plasma excitation and prevents high-frequency interference with argon ion bombardment and activation of the MoS2. The chamber wall temperature is also maintained at ≤40°C to prevent local overheating that could cause MoS2 oxidation or increase sulfur vacancies. Maintaining this RF power, frequency, and chamber wall temperature for 5-10 minutes effectively removes contaminants from the MoS2 surface, optimizes the MoS2 surface modification, enhances the interfacial compatibility between MoS2 and subsequent polymers, and ensures the integrity of the MoS2 nanosheets.

[0024] Plasma treatment is a physical and chemical process in which ionized gas generates highly reactive particles (such as electrons, ions, and free radicals). These high-energy particles in the plasma then bombard and modify the material surface, degrading surface materials and increasing surface roughness. This technique not only improves material performance but also enhances durability and reliability. Argon ions, accelerated by a radio frequency electric field, bombard the MoS2 surface, stripping away weakly bound sulfur atoms. The resulting sulfur vacancies serve as anchoring sites for the subsequent addition of a silane coupling agent. Simultaneously, the high-energy electrons in the plasma break Mo-S bonds, creating dangling bonds and forming active Mo sites on the surface that chemically bond with the silanols in the silane coupling agent. This effectively increases the grafting efficiency of the MoS2 onto the silane coupling agent and ensures the presence of amino groups on the MoS2 surface, paving the way for the subsequent covalent grafting of carboxyl-terminated fluorinated poly(arylethersulfone).

[0025] S1.2. Slowly add the plasma-treated molybdenum disulfide nanosheets into anhydrous solvent I, ultrasonically disperse at 40 kHz, 300 W for 20 to 30 minutes, add a silane coupling agent, and magnetically stir at a speed of 300 to 500 rpm for 10 to 15 minutes to fully dissolve it to obtain modified molybdenum disulfide nanosheets.

[0026] Ultrasonic dispersion of MoS2 nanosheets overcomes the van der Waals forces between MoS2 layers, enabling interlayer exfoliation. This further activates the surface-grafted hydroxyl groups under cavitation, promoting penetration of solvent molecules into the interstices between the nanosheets. Controlling the ultrasonic frequency to 40 kHz, which falls within the optimal cavitation efficiency range (20–50 kHz), balances penetration depth and energy density, avoiding energy insufficiency caused by too low a frequency and the generation of free radical side reactions that can occur with too high a frequency. Controlling the ultrasonic power to 300 W ensures an energy density above 1.5 W / mL, increasing the dispersion rate of MoS2 into a single layer. At this ultrasonic frequency and power, sonication for 20–30 minutes avoids insufficient MoS2 dispersion due to too short a time, and increased MoS2 flake breakage due to too long a time. Controlling the stirring speed to 300–500 rpm creates an appropriate vortex, balancing mixing efficiency with bubble generation and preventing silane hydrolysis caused by high-speed stirring.

[0027] Ultrasonic dispersion uses liquid as a medium, creating cavitation through the action of ultrasound waves in the liquid. The high-speed microfluidics generated by ultrasonic cavitation at the solid-liquid interface can remove or weaken the boundary contamination layer, enhance the stirring effect, and disperse and deagglomerate particles in the liquid. As a physical method and tool, it can create various extreme conditions in liquids. 40kHz ultrasound generates cavitation bubbles, which instantly collapse to form localized high-pressure and high-speed microjets, effectively exfoliating MoS2 stacks and reducing the thickness of MoS2 nanosheets. Furthermore, after ultrasound treatment, the absolute value of the Zeta potential increases, and electrostatic repulsion is strengthened, effectively preventing the reagglomeration of MoS2 nanosheets.

[0028] S1.3. Add carboxyl-terminated fluorinated polyarylethersulfone with a fluorine content of 12% in batches, stir in a water bath at 60°C until completely dissolved, then add N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine in sequence, stir for 15-20 minutes, add 2 drops of glacial acetic acid, adjust the pH of the reaction system to 5-6, place in a microwave reactor, and react at 75-85°C for 30-45 minutes at a power of 300-350 W and a pulse mode of 10s on / 5s off. Then pour into 200 mL of ethanol for precipitation, and centrifuge at 7000-8000 rpm for 10-20 minutes to obtain a fluorinated polyarylethersulfone-molybdenum disulfide modified composite.

[0029] The water bath temperature is controlled at about 60°C to balance the dissolution rate and solvent volatility, and is lower than the polymer glass transition temperature to avoid molecular chain degradation. The stirring dissolution time is controlled at 15-20 min to avoid too short time, incomplete activation of carboxyl group due to incomplete catalytic effect of N,N'-dicyclohexyl carbodiimide, and to affect the grafting rate of carboxyl-terminated fluorine-containing polyarylether sulfone and silanized molybdenum disulfide, and to accelerate the acyl transfer of 4-dimethylamino pyridine and inhibit side reactions to avoid invalid consumption of active groups. The pH of the reaction system is adjusted to 5-6, and the acidic environment (pH < 7) can promote the stability of Si-O bond of silane modified molybdenum disulfide and inhibit the hydrolysis of N,N'-dicyclohexyl carbodiimide.

[0030] The microwave power is controlled at 300-350 W to ensure rapid heating of the reaction system, and to avoid local overheating leading to oxidation of molybdenum disulfide. The pulse mode is controlled at 10 s on / 5 s off, and intermittent heating can maintain temperature uniformity to prevent polymer heat aggregation. The system reaction temperature is controlled at 75-85°C to balance the reaction rate and side reaction control. Under the conditions of microwave power, pulse mode and reaction temperature, microwave treatment for 30-45 min can enable sufficient grafting of carboxyl-terminated fluorine-containing polyarylether sulfone and silanized molybdenum disulfide to improve the grafting rate, and can avoid the occurrence of crosslinking and other side reactions caused by too long reaction time. The centrifugal speed is controlled at 7000-8000 rpm to provide about 6000 x g centrifugal force to fully separate the nanocomposites. Centrifugation for 10-20 min at this centrifugal speed can avoid incomplete precipitation of nanocomposites caused by too short centrifugation time, and can avoid compacted precipitation of nanocomposites which is difficult to redisperse caused by too long centrifugation time. Microwave reaction refers to a process in which molecules or ions of a substance absorb microwave energy and convert it into heat energy to initiate a chemical reaction under the action of a microwave field. Microwave interacts with fluorine-containing polyarylether sulfone through dipole polarization to cause high-frequency rotational motion of C-F bond of fluorine-containing polyarylether sulfone, generate heat through molecular friction, reduce the activation energy of C-F bond, enhance the mobility and effective collision probability of molecular chain, and improve the reaction rate constant of the system. In addition, microwave can intensify the vibration of N=C=N bond of N,N'-dicyclohexyl carbodiimide to promote the activation of carboxyl group, and the orientation arrangement of 4-dimethylamino pyridine in the microwave field can also effectively improve its catalytic efficiency. At the same time, the microwave field can induce the directional arrangement of silanol of silane coupling agent on the surface of molybdenum disulfide and carboxyl of fluorine-containing polyarylether sulfone to improve the grafting density of the two, which is more conducive to the grafting reaction of carboxyl-terminated fluorine-containing polyarylether sulfone and modified molybdenum disulfide nanosheet.

[0031] Carboxyl-terminated fluorinated poly(arylethersulfone) is a specially modified polymer material with high mechanical strength, excellent thermal stability, and corrosion resistance. The presence of C-H bonds imparts excellent hydrophobicity to the material, while the presence of carboxyl groups allows for chemical bonding with metal substrates, resulting in excellent adhesion. It has broad applications in a variety of fields, including electronic packaging, precision instrumentation, aerospace, high-temperature resistant coatings, and advanced composite materials. The carboxyl groups at the end of the carboxyl-terminated fluorinated poly(arylethersulfone) react with the amino groups on the surface of molybdenum disulfide modified with a silane coupling agent under the action of a catalyst to form amide bonds, achieving molecular-level interfacial bonding between the polymer and the nanosheets. Fluorine atoms, with their strong electronegativity, are introduced into the poly(arylethersulfone) backbone, effectively reducing the dielectric constant and optimizing the dielectric properties of the molybdenum disulfide nanosheets. The poly(arylethersulfone) backbone synergizes with the molybdenum disulfide to achieve a thermal decomposition temperature of 480°C, improving the high-temperature resistance of the MoS2 coating. The fluorine segments, in combination with the fluorine segments, impart chemical stability and low surface energy to the MoS2 coating.

[0032] S2. Prepare the oil phase and the water phase separately, mix and emulsify them, then heat them to 60-75°C, add a chain extender and a catalyst to carry out polymerization reaction, and obtain microcapsules.

[0033] In step S2, the fluorine-containing polyol is one or more of perfluoropolyether diol, fluorinated polycarbonate diol and fluorinated polyester diol, the diisocyanate is one or more of toluene diisocyanate, diphenylmethane diisocyanate and isophorone diisocyanate, the surfactant is sodium lauryl sulfate, the chain extender is one or more of ethylenediamine, 1,4-butanediol and adipic acid dihydrazide, the catalyst is stannous octoate, the amount of dimethyl disulfide is 30-35% of the mass of the prepolymer, the mass ratio of the fluorine-containing polyol to the diisocyanate is 2-7:1-3, the amount of the surfactant is 0.5-1% of the mass of the aqueous phase, and the amount of the chain extender is 2-5% of the mass of the prepolymer.

[0034] Step S2 includes: S2.1. Add dimethyl disulfide and fluorinated polyol into a reaction vessel respectively. After magnetic stirring at 200-300 rpm for 15-20 min, slowly add diisocyanate dropwise and stir in an ice bath for 30-40 min to form a prepolymer to obtain an oil phase. At the same time, add deionized water and surfactant into another reaction vessel respectively. Stir in a 40°C water bath until dissolved to obtain an aqueous phase.

[0035] Magnetic stirring at a controlled speed of 200-300 rpm for 15-20 minutes ensures uniform mixing of the reactants while avoiding splashing. Stirring the reaction in an ice bath can suppress the rapid exothermic reaction between the diisocyanate and the hydroxyl group, preventing localized overheating. Stirring the reaction in an ice bath for 30-40 minutes ensures that the NCO groups (isocyanate groups) fully react with the OH groups to form urethane bonds. Keeping the water bath temperature around 40°C accelerates surfactant dissolution, but below its cloud point.

[0036] Dimethyl disulfide is a synthetic organosulfur compound that is slightly soluble in water but readily soluble in organic solvents. It is thermally stable, hydrophobic, and has a low boiling point. Its disulfide bonds can break under the action of reducing agents, generating methyl mercaptan, or can undergo homolytic cleavage under high temperatures or light, forming free radicals. In the preparation of polyurethane microcapsules, dimethyl disulfide typically does not participate in the reaction and is only encapsulated as an inert core material. When microcracks form in the coating, the microcapsules rupture, releasing dimethyl disulfide. The disulfide bonds in dimethyl disulfide can undergo a reversible sulfur exchange reaction with the thiol groups in the polyurethane, achieving efficient self-healing of the cracks.

[0037] The n-butylamine titration method is used to track the consumption of NCO groups. This method can provide real-time information on the concentration of residual isocyanate in the reaction system, reflecting the progress of the system in real time, avoiding overreaction or continued side reactions, and ensuring that the final polyurethane prepolymer has a predictable NCO content and molecular weight distribution.

[0038] Accurately weigh 1.0g of polyurethane prepolymer sample, in an airtight environment, quickly inject the sample into a weighed conical flask containing 25.00mL of anhydrous toluene, and stir magnetically in a 30℃ water bath until completely dissolved. Add 15.00mL of 0.1mol / L n-butylamine solution to the sample bottle, seal the bottle mouth, and react at 25℃ for 20min, shaking every 5min to ensure complete reaction. Add 50mL of isopropanol to dilute, immediately add 5 drops of bromophenol blue indicator, and titrate with 0.1mol / L hydrochloric acid standard solution to the yellow end point. The volume of hydrochloric acid consumed is recorded as V 1. Set up a blank control group and titrate the n-butylamine solution without adding sample in the same way. The volume of hydrochloric acid consumed is V 0. Calculate the concentration of NCO groups based on the volume of hydrochloric acid consumed to determine whether the reaction is complete. When the concentration of NCO groups reaches the set value, stop the reaction. The calculation formula is: in, V 0 is the volume of hydrochloric acid consumed by the blank control group, in mL; V 1 is the volume of hydrochloric acid consumed when titrating the sample, in mL;C HCl is the concentration of hydrochloric acid, 0.1 mol / L; m The sample is the mass of the polyurethane prepolymer sample, 1.0 g.

[0039] In the above-mentioned testing process, the preset concentration of isocyanate groups is 3%~5%.

[0040] S2.2. The oil phase solution is dropped into the aqueous phase at a rate of 0.5 ml / min. At the same time, high-speed shear emulsification is performed at 8000-10000 rpm for 10-15 min to form an O / W emulsion. The temperature is raised to 60-75°C, and a chain extender and a catalyst are added. After reacting under nitrogen protection for 6-8 hours, the emulsion is cooled to room temperature and centrifuged at 5000-6000 rpm for 3-5 minutes. The emulsion is washed with an ethanol / water mixture with a volume ratio of 1:1 and passed through a 400-mesh sieve to obtain microcapsules with a particle size distribution of 2-5 μm.

[0041] Controlling the oil phase solution dropwise addition rate at 0.5 ml / min prevents localized excessive concentrations from causing uneven emulsion formation and ensures stable oil phase dispersion. A shear rate of 8,000–10,000 rpm provides high shear force, breaking up oil phase droplets and forming fine, uniform emulsion particles. High-speed shear emulsification at this shear rate for 10–15 minutes ensures sufficient emulsification while avoiding prolonged shearing that could lead to temperature increases and demulsification. The reaction temperature is controlled between 60 and 75°C, above the active temperature of the chain extender but below the boiling point of dimethyl disulfide to prevent core material volatilization. A nitrogen atmosphere is introduced to prevent oxygen from interfering with the polymerization reaction and side reactions such as oxidation and bubble formation. A reaction time of 6–8 hours at this temperature and atmosphere ensures sufficient consumption of -NCO groups and complete crosslinking of the wall material. Controlling the centrifugal speed between 5000 and 6000 rpm balances separation efficiency and microcapsule integrity, avoiding wall material rupture caused by excessively high speeds. Centrifuging at this speed for 3 to 5 minutes effectively separates microcapsules from unreacted monomers. Washing with a 1:1 ethanol / water mixture is recommended. This ratio balances solubility and microcapsule stability, and it simultaneously removes organic residues and water-soluble impurities. Using a 400-mesh sieve ensures uniform particle size distribution and removes oversized particles or agglomerates.

[0042] S3. Dissolve the modified composite in anhydrous solvent II, add graphene quantum dots, and after ultrasonic treatment, add microcapsules, flame retardant, and pentaerythritol tetrakis-3-mercaptopropionate respectively, stir and solidify to obtain a molybdenum disulfide coating.

[0043] In step S3, the anhydrous solvent II is N-methylpyrrolidone with a purity of ≥99.8%, the flame retardant is a DOPO derivative FR-102 flame retardant, the mass ratio of the modified composite to the graphene quantum dots is 5-9:1-3, the amount of the anhydrous solvent II is 60-70% of the mass of the molybdenum disulfide coating, the mass ratio of the microcapsules to pentaerythritol tetrakis-3-mercaptopropionate is 4-6:1-2, and the amount of the flame retardant is 2-5% of the mass of the molybdenum disulfide coating.

[0044] Step S3 includes: S3.1. Add the modified complex to anhydrous solvent II and magnetically stir at 200-300 rpm and 50-60°C for 1-2 hours until completely dissolved. Then add graphene quantum dots with a diameter of 3-5 nm and ultrasonically treat at 40 kHz and 300 W for 25-30 minutes to obtain a three-dimensional lubricating network.

[0045] Controlling the stirring speed at 200-300 rpm can balance the dissolution efficiency and avoid solvent volatilization. Controlling the system reaction temperature at 50-60°C promotes the full dissolution of the modified complex, but below the boiling point of anhydrous solvent II to avoid solvent evaporation. Stirring at this stirring speed and reaction temperature for 1-2 hours can ensure the full stretching of the molecular chains of the complex, which is conducive to the subsequent full combination with graphene quantum dots. Controlling the ultrasonic frequency at 40kHz and the power at 300W can ensure the effective cavitation and uniform dispersion of the graphene quantum dots, avoiding the agglomeration of the graphene quantum dots. Ultrasonic treatment under these ultrasonic conditions for 25-30 minutes can avoid the uneven dispersion of the graphene quantum dots caused by too short a time, and the destruction of the graphene quantum dot structure caused by too long a time.

[0046] Graphene quantum dots are a quasi-zero-dimensional nanomaterial consisting of 1 to 3 layers of graphene sheets, with oxygen-rich edges and sp 2 Hybrid carbon networks have good mechanical properties and are often used in various fields such as bioimaging, optoelectronic devices, coating materials, and drug carriers. As a lubricating reinforcement phase, quantum dots have low interlayer shear strength, and interlayer sliding can effectively reduce the friction coefficient of the coating. The carboxyl groups of graphene quantum dots react with the amino groups of the modified complex to form covalent bonds, thereby increasing the crosslinking density of the molybdenum disulfide coating material. The hydroxyl groups of graphene quantum dots react with the ether bonds of the modified complex to form intermolecular hydrogen bonds. The sp 2 The hybridized carbon interacts with the aromatic rings of the modified composite, connecting the modified composite through covalent bonds, hydrogen bonds, and π-π stacking, becoming a "molecular bridge" connecting the functional components. This achieves synergistic optimization of lubricity, flame retardancy, and mechanical strength, significantly improving the tensile strength of the MoS2 coating and forming a spatial support structure. Furthermore, the graphene quantum dots fill the interlayer gaps of the MoS2 coating, effectively inhibiting the propagation of microcracks and improving the fracture toughness of the MoS2 coating.

[0047] A 100 mm × 100 mm × 3 mm aluminum alloy substrate was sandpapered and then coated with a molybdenum disulfide coating. The coating was cured for 24 hours at 23 ± 2°C and 50 ± 5% relative humidity. Five measurement points were evenly selected on the sample surface and the thickness was measured using a film thickness gauge to ensure a coating thickness of 20 ± 2 μm. After equilibrating for 4 hours at 23 ± 1°C and 50 ± 3% relative humidity, the coated sample was secured to the test platform using double-sided conductive adhesive. A pre-treated 25 mm × 25 mm stainless steel slider was connected to the force sensor via a universal joint. A 50 g preload was applied for 30 seconds. The sensor position was adjusted to ensure that the slider was in complete parallel contact with the sample surface. The test program was initiated, and the slider moved 70 mm across the sample surface at a speed of 100 ± 5 mm / min. The force sensor system automatically recorded the friction force changes at a sampling frequency of 200 Hz. The normal load was set to 200 g, and each sample was tested 5 times in different areas of the surface, with an interval of 5 minutes between each test. The friction curve was monitored in real time. Specifically, Friction coefficient ( μ ) is calculated as: in, F The average friction force within the range of 40-60mm during the movement of the slider, in N; N is the normal load, which is 200 g; n is a valid data point.

[0048] The friction coefficient of the prepared MoS2 coating in air ( μ ) ≤0.1, with a low friction coefficient, which can reduce the wear between the contact surfaces, extend the service life of the coating and the base material, while reducing energy loss and improving the operating efficiency of mechanical equipment.

[0049] S3.2. Slowly add microcapsules and magnetically stir at a stirring speed of 100-150 rpm for 40-60 minutes. Add flame retardants in batches, stirring for 5 minutes for each 1 g. Then inject pentaerythritol tetrakis-3-mercaptopropionate and continue stirring until the viscosity of the system is stable. After curing in a 70-80 ° C oven for 1-2 hours, increase the temperature to 150-200 ° C at a heating rate of 2 ° C / min, keep warm for 1-2 hours, and then naturally cool to 80 ° C and maintain for 1 hour to obtain a cured molybdenum disulfide coating.

[0050] During the n-butylamine titration test, the preset concentration of isocyanate groups was 0.3% to 0.5%. Low-shear mixing of the microcapsules, modified composite, and graphene quantum dots prevents the vertical alignment of the MoS2 coating from being disrupted after the introduction of the microcapsules and solvent, which could affect its lubricity.

[0051] Keeping the stirring speed between 100-150 rpm and slow stirring effectively prevents shear forces from damaging the microcapsule wall material. Stirring at this speed for 40-60 minutes ensures adequate wetting of the microcapsules into the substrate and prevents sedimentation. Adding flame retardants for 5 minutes per gram effectively balances dispersion efficiency and reaction rate, preventing flame retardant agglomeration. Maintaining the initial curing temperature of the molybdenum disulfide coating at 70-80°C, below the boiling point of dimethyl disulfide, protects the integrity of the core material. Curing at this temperature for 1-2 hours allows for slow solvent evaporation, ensuring residual solvent levels below 3%. Maintaining the ramp rate at 2°C / min prevents thermal shock cracking of the microcapsules caused by excessive heating. Maintaining the ramp temperature at 150-200°C promotes lattice rearrangement of the molybdenum disulfide. Maintaining the temperature at this rate and temperature for 1-2 hours promotes sufficient crosslinking of the molybdenum disulfide coating system, ensuring a high crosslink density. Controlling the annealing temperature at 80°C and maintaining it for 1 hour can effectively release the internal stress of the coating system and ensure the stability of the coating material.

[0052] Pentaerythritol tetrakis-3-mercaptopropionate is an excellent thioester antioxidant with a high unit sulfur content. The structure containing pentaerythritol exhibits excellent high temperature resistance and water extraction resistance. The thiol group of pentaerythritol tetrakis-3-mercaptopropionate will undergo a nucleophilic addition reaction with the remaining isocyanate groups in the prepolymer to form thiocarbamate bonds, thereby enhancing the mechanical strength of the molybdenum disulfide coating and introducing thiol groups on the surface of the polyurethane shell, thereby improving the sulfur exchange repair efficiency of dimethyl disulfide.

[0053] The present invention provides a molybdenum disulfide coating, which is prepared by the above-mentioned preparation method of the molybdenum disulfide coating, comprising molybdenum disulfide nanosheets, anhydrous solvent I, a silane coupling agent, carboxyl-terminated fluorinated polyarylethersulfone, N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine, dimethyl disulfide, fluorinated polyol, diisocyanate, surfactant, chain extender, catalyst, anhydrous solvent II, graphene quantum dots, flame retardant, and pentaerythritol tetrakis-3-mercaptopropionate; wherein, MoS2 nanosheets serve as the core lubricating phase, providing an ultra-low friction surface through a vertically oriented layered structure, thus enhancing the wear resistance of the MoS2 coating. Silane coupling agents bridge molybdenum disulfide and fluorinated polyarylethersulfone through covalent bonds, thereby enhancing the inorganic-organic interface bonding strength of the molybdenum disulfide coating and preventing the peeling of molybdenum disulfide nanosheets. Carboxyl-terminated fluorinated poly(arylethersulfone) is used to provide high-temperature-resistant active sulfone groups to MoS2 nanosheets, and to construct a low-surface-energy interface with the fluorine segments, thereby improving the high-temperature resistance and chemical stability of the MoS2 coating. N,N'-dicyclohexylcarbodiimide is used to catalyze the amidation reaction between the carboxyl group of carboxyl-terminated fluorinated poly(arylethersulfone) and silylated MoS2, thereby increasing the grafting rate and avoiding the consumption of active groups by side reactions. 4-Dimethylaminopyridine was used as a proton transfer catalyst to accelerate the conversion efficiency of N,N'-dicyclohexylcarbodiimide intermediates, effectively shortening the microwave-assisted grafting reaction time of molybdenum disulfide coatings. Dimethyl disulfide is used to provide the core material of polyurethane microcapsules, achieving coating self-repair through dynamic sulfur exchange reaction, and enhancing the crack self-repair function of molybdenum disulfide coating; Fluorinated polyols are used to introduce fluorinated segments into the polyurethane microcapsule shell to enhance compatibility with the carboxyl-terminated fluorinated polyarylethersulfone matrix and prevent the agglomeration of polyurethane microcapsules. Diisocyanate is used to react to form the polyurethane microcapsule shell and improve the dimethyl disulfide release rate of the molybdenum disulfide coating; Chain extenders are used to adjust the mechanical properties of the polyurethane shell and improve the hardness and toughness of the molybdenum disulfide coating; Graphene quantum dots are used to fill interlayer defects in MoS2, construct a three-dimensional heat-conducting and lubricating network, and improve the in-plane thermal conductivity and wear resistance of the MoS2 coating. Pentaerythritol tetrakis-3-mercaptopropionate is used to provide high-density thiol groups in polyurethane prepolymers, which undergo a reversible sulfur exchange reaction with dimethyl disulfide to improve the indoor self-healing rate of molybdenum disulfide coatings.

[0054] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a molybdenum disulfide coating, characterized in that the steps include: S1, plasma-treating molybdenum disulfide nanosheets and dissolving them in anhydrous solvent I, adding a silane coupling agent, carboxyl-terminated fluorinated polyarylethersulfone, N,N'-dicyclohexylcarbodiimide, and 4-dimethylaminopyridine, stirring and dissolving, adjusting the pH to 5-6, and microwave-treating to obtain a fluorinated polyarylethersulfone-molybdenum disulfide modified composite; S2, separately preparing an oil phase and an aqueous phase, mixing and emulsifying them, raising the temperature and adding a chain extender and a catalyst to carry out a polymerization reaction to obtain microcapsules; S3. Dissolve the modified composite in anhydrous solvent II, add graphene quantum dots, and after ultrasonic treatment, add microcapsules, flame retardant, and pentaerythritol tetrakis-3-mercaptopropionate respectively, stir and solidify to obtain a molybdenum disulfide coating.

2. The method for preparing a molybdenum disulfide coating according to claim 1, wherein: In step S1, the thickness of the molybdenum disulfide nanosheets is less than 5 nm and the diameter is 1-2 μm; the anhydrous solvent I is N-methylpyrrolidone with a purity of ≥99.99%; the silane coupling agent is one or more of silane coupling agent KH-550, silane coupling agent A-1120, and silane coupling agent A-1100; the mass ratio of the molybdenum disulfide nanosheets to the silane coupling agent is 4-7:1-3; and the amount of the anhydrous solvent I is 10-15% of the mass of the polyurethane prepolymer.

3. The method for preparing a molybdenum disulfide coating according to claim 1, wherein: Step S1 includes: S1.

1. Weigh molybdenum disulfide nanosheets, spread them evenly on a quartz carrier, and after vacuum drying, place them in a plasma chamber. Flow 99.99% pure argon into the chamber at a flow rate of 20-25 sccm, maintaining a dynamic pressure of 0.1-0.3 mbar. Turn on the RF power supply, set the power to 100 W, and the frequency to 13.56 MHz. Ensure that the chamber wall temperature is ≤40°C. Continue the treatment for 5-10 minutes to obtain plasma-treated molybdenum disulfide. S1.

2. Slowly add the plasma-treated MoS2 nanosheets to anhydrous solvent I. After ultrasonic dispersion, add a silane coupling agent and magnetically stir at 300-500 rpm for 10-15 minutes to fully dissolve the modified MoS2 nanosheets. S1.

3. Add carboxyl-terminated fluorinated polyarylethersulfone with a fluorine content of 12% in batches, stir in a water bath at 60°C until completely dissolved, then add N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine in sequence, stir for 15-20 minutes, add 2 drops of glacial acetic acid, adjust the pH of the reaction system to 5-6, place in a microwave reactor, and react at 75-85°C for 30-45 minutes at a power of 300-350W and a pulse mode of 10s on / 5s off. Then pour into 200 mL of ethanol for precipitation, and obtain a fluorinated polyarylethersulfone-molybdenum disulfide modified composite after high-speed centrifugation.

4. The method for preparing a molybdenum disulfide coating according to claim 1, wherein: In step S2, the fluorine-containing polyol is one or more of perfluoropolyether diol, fluorinated polycarbonate diol and fluorinated polyester diol; the diisocyanate is one or more of toluene diisocyanate, diphenylmethane diisocyanate and isophorone diisocyanate; the surfactant is sodium lauryl sulfate; the chain extender is one or more of ethylenediamine, 1,4-butanediol and adipic acid dihydrazide; and the catalyst is stannous octoate.

5. The method for preparing a molybdenum disulfide coating according to claim 1, wherein: The amount of dimethyl disulfide used is 30-35% of the mass of the prepolymer; the mass ratio of the fluorinated polyol to the diisocyanate is 2-7:1-3; the amount of the surfactant used is 0.5-1% of the mass of the aqueous phase; and the amount of the chain extender used is 2-5% of the mass of the prepolymer.

6. The method for preparing a molybdenum disulfide coating according to claim 1, wherein: Step S2 includes: S2.

1. Add dimethyl disulfide and fluorinated polyol to a reaction vessel, stir magnetically at 200-300 rpm for 15-20 min, then slowly add diisocyanate dropwise and stir on ice for 30-40 min to form a prepolymer to obtain an oil phase. Simultaneously, add deionized water and surfactant to another reaction vessel, stir in a 40°C water bath until dissolved, to obtain an aqueous phase. S2.

2. The oil phase solution is dropped into the aqueous phase at a rate of 0.5 ml / min. At the same time, high-speed shear emulsification is performed at 8000-10000 rpm for 10-15 min to form an O / W emulsion. The temperature is raised to 60-75°C, and a chain extender and a catalyst are added. After reacting under nitrogen protection for 6-8 hours, the emulsion is cooled to room temperature and centrifuged at 5000-6000 rpm for 3-5 minutes. The emulsion is washed with an ethanol / water mixture with a volume ratio of 1:1 and passed through a 400-mesh sieve to obtain microcapsules with a particle size distribution of 2-5 μm.

7. The method for preparing a molybdenum disulfide coating according to claim 1, wherein: In step S3, the anhydrous solvent II is N-methylpyrrolidone with a purity of ≥99.8%; the flame retardant is a DOPO derivative FR-102 flame retardant; the mass ratio of the modified composite to the graphene quantum dots is 5-9:1-3; the amount of the anhydrous solvent II is 60-70% of the mass of the molybdenum disulfide coating; the mass ratio of the microcapsules to the pentaerythritol tetrakis-3-mercaptopropionate is 4-6:1-2; and the amount of the flame retardant is 2-5% of the mass of the molybdenum disulfide coating.

8. The method for preparing a molybdenum disulfide coating according to claim 1, wherein: Step S3 includes: S3.

1. Add the modified composite to anhydrous solvent II and magnetically stir until completely dissolved. Then, add graphene quantum dots with a diameter of 3 to 5 nm and ultrasonically treat at 40 kHz and 300 W for 25 to 30 minutes to obtain a three-dimensional lubricated network. S3.

2. Slowly add microcapsules and magnetically stir at a stirring speed of 100-150 rpm for 40-60 minutes. Add flame retardants in batches, stirring for 5 minutes after each addition of 1 g. Then inject pentaerythritol tetrakis-3-mercaptopropionate and continue stirring until the viscosity of the system is stable. After pre-curing in an oven at 70-80°C for 1-2 hours, increase the temperature in steps of 2°C / min to 150-200°C, keep warm for 1-2 hours, and then naturally cool to 80°C and maintain for 1 hour to obtain a cured molybdenum disulfide coating.

9. A molybdenum disulfide coating, characterized in that: The molybdenum disulfide coating is prepared by the preparation method of any one of claims 1 to 8, comprising molybdenum disulfide nanosheets, anhydrous solvent I, a silane coupling agent, carboxyl-terminated fluorinated polyarylethersulfone, N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine, dimethyl disulfide, fluorinated polyol, diisocyanate, surfactant, chain extender, catalyst, anhydrous solvent II, graphene quantum dots, flame retardant, and pentaerythritol tetrakis-3-mercaptopropionate; wherein, The molybdenum disulfide nanosheets serve as a core lubricating phase, providing an ultra-low friction surface through a vertically oriented layered structure, thereby enhancing the wear resistance of the molybdenum disulfide coating; The silane coupling agent bridges the molybdenum disulfide and the fluorinated polyarylethersulfone through a covalent bond, thereby improving the inorganic-organic interface bonding strength of the molybdenum disulfide coating and preventing the molybdenum disulfide nanosheets from peeling off; The carboxyl-terminated fluorinated polyarylethersulfone is used to provide the molybdenum disulfide nanosheets with high-temperature resistant active groups such as sulfone groups, and to construct a low surface energy interface with the fluorine segments, thereby improving the high-temperature resistance and chemical stability of the molybdenum disulfide coating. The N,N'-dicyclohexylcarbodiimide is used to catalyze the amidation reaction between the carboxyl group of the carboxyl-terminated fluorinated polyarylethersulfone and silylated molybdenum disulfide, thereby increasing the grafting rate and preventing the side reaction from consuming the active group. The 4-dimethylaminopyridine is used as a proton transfer catalyst to accelerate the conversion efficiency of the N,N'-dicyclohexylcarbodiimide intermediate, effectively shortening the microwave-assisted grafting reaction time of the molybdenum disulfide coating; The dimethyl disulfide is used to provide a polyurethane microcapsule core material, and the coating self-repair is achieved through a dynamic sulfur exchange reaction, thereby enhancing the crack self-repair function of the molybdenum disulfide coating; The fluorinated polyol is used to introduce fluorinated segments into the polyurethane microcapsule shell, thereby enhancing compatibility with the carboxyl-terminated fluorinated polyarylethersulfone matrix and preventing the polyurethane microcapsules from agglomerating. The diisocyanate is used to react to form a polyurethane microcapsule shell, thereby improving the dimethyl disulfide release rate of the molybdenum disulfide coating; The chain extender is used to adjust the mechanical properties of the polyurethane shell and improve the hardness and toughness of the molybdenum disulfide coating; The graphene quantum dots are used to fill the interlayer defects of the molybdenum disulfide, construct a three-dimensional heat conduction-lubrication network, and improve the in-plane thermal conductivity and wear resistance of the molybdenum disulfide coating; The pentaerythritol tetrakis-3-mercaptopropionate is used to provide a high-density thiol group in the polyurethane prepolymer, which undergoes a reversible sulfur exchange reaction with dimethyl disulfide, thereby improving the indoor self-repair rate of the molybdenum disulfide coating.

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