Super-slippery microcapsules and composites thereof and methods of making the same

Abstract

This invention discloses a superlubricating microcapsule, its composite material, and a method for preparing them. The superlubricating microcapsule comprises a core material and a wall material covering the core material. The core material includes component A and component B. Component A is one or more of the following: molybdenum dialkyl dithiophosphate oxydiphosphate, molybdenum dialkyl dithiocarbamate, molybdenum amine complex, molybdenum naphthenate, molybdenum alkyl salicylate, nitrogen-containing molybdenum dialkyl dithiophosphate oxydiphosphate, bisphenol molybdenum, molybdenum thiophosphate, molybdenum hydroxamic acid, molybdenum fatty acid, organic molybdate, Schiff base molybdenum, trimeric molybdenum salt, ethyl thiotungstate, propyl thiotungstate, and butyl thiotungstate. Component B is an ionic liquid or lubricating oil. The superlubricating microcapsule composite material of this invention is made of superlubricating microcapsules and a matrix material with a core-shell structure. The matrix material includes a solid lubricant core material and a polymer shell material covering the core material. The preparation method of this invention is simple, feasible, and highly operable, enabling macroscopic superlubricity in atmospheric environments, and has high application value.

Description

Technical Field

[0001] This invention relates to a superlubricating microcapsule and its composite material and their preparation method, belonging to the field of lubricating material technology. Background Technology

[0002] Microencapsulation technology refers to a micro-packaging technology that encapsulates trace amounts of substances within polymer films for storing solids, liquids, and gases. Besides possessing the advantages of both core and shell materials, microcapsule materials exhibit unique properties significantly different from simple blends or copolymers due to the synergistic effect between the core and shell components. With different characteristic components, morphologies, controllable particle size, and synergistic effects between components, microcapsules are widely used in electronics, food, pharmaceuticals, cosmetics, agriculture, and biology, with a very promising future. Furthermore, microcapsules are widely used to adjust or enhance the lubrication properties of materials, playing a crucial role in tribology. Superlubricity refers to a lubrication state with extremely low or even completely absent frictional resistance (friction coefficient below 0.01), representing the ultimate goal of lubrication technology development. It can significantly reduce energy dissipation at the friction interface, effectively extending component life and enhancing its reliability. The lubricant within the microcapsule is encapsulated in a solid shell and can be used as a lubricating and reinforcing filler in polymer composites, thereby enabling the real-time release of the lubricant from the microcapsule under interfacial stress stimulation during friction. Microcapsules, due to their ability to respond automatically without external lubrication, hold great potential for improving the service performance of critical moving parts in advanced equipment. By introducing microcapsules, the lubrication properties of polymer composites can be significantly improved, reducing the coefficient of friction (COF) of the resin matrix to ~0.02. Nevertheless, achieving superlubricity in microcapsule composites remains a challenge, partly because oil evaporation and shell decomposition make it difficult to incorporate microcapsules into low-friction matrices with high molding temperatures (>250°C), such as polytetrafluoroethylene (PTFE). Therefore, exploring novel microcapsule composite systems to achieve a superlubricated state with a COF below 0.01 is of extremely high research value. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a superlubricating microcapsule and its composite material and their preparation method, that is, to achieve the composite of microcapsules with a low-friction polymer matrix, thereby achieving macroscopic superlubricity in an atmospheric environment.

[0004] In a first aspect, the present invention provides an ultra-slippery microcapsule, comprising a core material and a wall material covering the core material;

[0005] The core material includes component A and component B;

[0006] Component A is one or more of the following: molybdenum dialkyl dithiophosphate oxy, molybdenum dialkyl dithiocarbamate, molybdenum amine complex, molybdenum naphthenate, molybdenum alkyl salicylate, nitrogen-containing molybdenum dialkyl dithiophosphate oxy, bisphenol molybdenum, molybdenum thiophosphate, molybdenum hydroxamic acid, molybdenum fatty acid, organic molybdate, Schiff base molybdenum, trimeric molybdenum salt, ethyl thiotungstate, propyl thiotungstate, butyl thiotungstate, and ammonium thiotungstate.

[0007] Component B is an ionic liquid or a lubricating oil. The ionic liquid includes one or more of the following: 1-butyl-3-methylimidazolium hexafluorophosphate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-octyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. The lubricating oil includes one or more of the following: PAO base oil, linseed oil, alkyl silicone oil, phenyl silicone oil, chain oil, tung oil, mineral oil, ester base oil, liquid paraffin, perfluoropolyether, heavy alkylbenzene, and oleic acid.

[0008] In the aforementioned super-lubricating microcapsules, the mass of component A is 0.1 to 50 wt% of the total mass of the core material.

[0009] In the aforementioned super-slippery microcapsules, the wall material includes one or more of polyimide, polysulfone, polyamide-imide, polyether-imide, polystyrene, urea-formaldehyde resin, and polymethyl methacrylate.

[0010] In the above-mentioned super-lubricating microcapsules, the particle size of the super-lubricating microcapsules is 100 nm to 1000 μm;

[0011] The wall thickness of the super-smooth microcapsules is 10 nm to 100 μm.

[0012] Secondly, the present invention provides a method for preparing the super-lubricating microcapsules described in any of the above claims, comprising the following steps:

[0013] 1) Mix component A and component B to obtain the core material;

[0014] 2) The core material and the wall material are mixed and dissolved in an organic solvent to obtain an oil phase;

[0015] 3) The oil phase is added to the aqueous phase consisting of surfactant and water, and the mixture is heated to react and obtain the super-slippery microcapsules.

[0016] In the above-mentioned method for preparing super-slippery microcapsules, in step 2), the mass ratio of the core material to the wall material is 1:(0.067-15), preferably 1:(0.25-2).

[0017] The organic solvent is dichloromethane, acetone, ethyl acetate, carbon tetrachloride, or petroleum ether;

[0018] In step 3), the oil phase is added to the aqueous phase under stirring or ultrasonic conditions. The stirring speed of the mechanical stirring is 200-2000 rpm, and the ultrasonic power is 50-1500 W.

[0019] The surfactant is one or a mixture of several of the following: polyvinyl alcohol, Triton X100, Tween 80, sodium dodecylbenzene sulfonate, ammonium dodecyl sulfate, hexadecyltrimethylammonium bromide, gelatin, gum arabic, and lignin.

[0020] The concentration of the surfactant in the aqueous phase is 0.05–10 wt%.

[0021] The heating temperature is between room temperature and 80°C, and the heating time is between 0.5 and 10 hours.

[0022] Thirdly, the present invention provides a superlubricating microcapsule composite material, which is made of any of the superlubricating microcapsules described above and a matrix material having a core-shell structure, wherein the matrix material includes a solid lubricant core material and a polymer shell material covering the core material.

[0023] In the above-mentioned super-lubricating microcapsule composite material, the solid lubricant core material is one or more of the following: polyimide, polytetrafluoroethylene, graphite, graphene, molybdenum disulfide, boron nitride, polyamide-imide, polyether-imide, tungsten disulfide, black phosphorus, polyether ether ketone, polyphenylene sulfide, fluorinated graphite, silver, and solid paraffin.

[0024] The polymer shell material is one or more of polyimide, polysulfone, polyamide-imide, polyether-imide, polystyrene, urea-formaldehyde resin, and polymethyl methacrylate;

[0025] The particle size of the matrix material is 100 nm to 100 μm;

[0026] The solid lubricant core material has a mass fraction of 5 to 95 wt% in the matrix material with a core-shell structure.

[0027] In the above-mentioned super-lubricating microcapsule composite material, the mass of the super-lubricating microcapsule accounts for 0.5 to 50 wt% of the total mass of the super-lubricating microcapsule composite material.

[0028] Fourthly, the present invention provides a method for preparing the super-lubricating microcapsule composite material as described in any of the above claims, comprising the following steps: mixing the super-lubricating microcapsules and the matrix material and then sintering them to obtain the super-lubricating microcapsule composite material.

[0029] In the above-mentioned method for preparing superlubricated microcapsule composite materials, the method for preparing the matrix material includes the following steps:

[0030] 1) The solid lubricant core material is dispersed in water to obtain a core material dispersion;

[0031] 2) Add the precursor and initiator of the polymer shell material to the core material dispersion, and heat under an inert atmosphere to react and obtain the matrix material.

[0032] In the above-mentioned method for preparing superlubricated microcapsule composite materials, the concentration of the solid core material dispersion is 1-50 vol%.

[0033] The reaction is carried out under stirring or ultrasonic conditions, with the stirring rate of mechanical stirring being 200–2000 rpm and the ultrasonic power being 50–1500 W.

[0034] The heating temperature is 40–90 °C, and the heating time is 4–12 hours.

[0035] In the above-mentioned method for preparing super-lubricating microcapsule composite materials, the pressure in the sintering step is 1-20 MPa and the sintering temperature is 80-300 ℃.

[0036] The present invention has the following beneficial effects:

[0037] Compared with existing technologies, this invention, based on microencapsulation technology and combined with solid-liquid coupling lubrication design, prepares microcapsules and their composite materials capable of achieving ultra-low lubrication states. The preparation method is simple, feasible, and highly operable. Different types, particle sizes, and encapsulation rates of microcapsules and their composite materials can be synthesized by controlling reaction conditions. Furthermore, macroscopic superlubricity can be achieved in atmospheric environments, demonstrating high application value. This invention improves the microcapsule composite material system, achieving macroscopic superlubricity in microcapsule composite materials and pioneering a new method for achieving macroscopic superlubricity under mild environmental conditions, providing a novel approach for further promoting the practical application of superlubricity in industry. Attached Figure Description

[0038] When considered in conjunction with the accompanying drawings, the invention will be more fully and better understood, and its many accompanying advantages will become readily apparent, by referring to the following detailed description. However, the accompanying drawings, which are provided to further illustrate the invention and form part of this invention, are used to explain the invention and do not constitute an undue limitation thereof, as shown in the figures:

[0039] Figure 1 This is a SEM image of the silicone oil / MoDTC@PS microcapsules in Example 1 of this invention;

[0040] Figure 2 This is a SEM image of the PTFE@PMMA matrix powder in Example 1 of the present invention;

[0041] Figure 3 This is a photograph of the microcapsule composite material sample from Example 1 of the present invention;

[0042] Figure 4 This is a TEM image of the PAO / MoDTC@PS microcapsules in Example 2 of this invention;

[0043] Figure 5 This is a graph showing the friction coefficient of the microcapsule composite material in Example 2 of the present invention. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0045] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0046] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0047] In this invention, numerical ranges are involved. Unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range.

[0048] Furthermore, when multiple scopes are provided to describe a feature or characteristic, these scopes may be merged. In other words, unless otherwise specified, all scopes disclosed herein should be understood to include any and all subscopes to which they are included. Additionally, in the description of the invention, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] As described in the background section, superlubricity refers to a lubrication state with extremely low or even completely absent frictional resistance (friction coefficient below 0.01), which can significantly reduce energy dissipation at the friction interface. However, the friction coefficient of current lubricating microcapsules can only reach a minimum of about 0.02. How to achieve the composite of microcapsules and low-friction polymer matrix to achieve macroscopic superlubricity in an atmospheric environment remains a technical problem that urgently needs to be solved.

[0050] Part One, the present invention provides a superlubricated microcapsule comprising a core material and a wall material covering the core material; the core material comprises component A and component B; component A is one or more of the following: molybdenum dialkyl dithiophosphate, molybdenum dialkyl dithiocarbamate (MoDTC), molybdenum amine complex, molybdenum naphthenate, molybdenum alkyl salicylate, nitrogen-containing molybdenum dialkyl dithiophosphate, bisphenol molybdenum, molybdenum thiophosphate, molybdenum hydroxamic acid, molybdenum fatty acid, organic molybdate, Schiff base molybdenum, tripolymolybdenum salt, ethyl thiotungstate, propyl thiotungstate, butyl thiotungstate, and ammonium thiotungstate; component B is an ionic liquid or a lubricating oil, wherein the ionic liquid comprises 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF)6), 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIM]PF6), and 1-ethyl-3-methylimidazolium hexafluorophosphate. The lubricant comprises one or more of the following: salt ([EMIM]PF6), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4), 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM]BF4), 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIM]BF4), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([BMIM][NTf2]), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([EMIM][NTf2]), and 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([OMIM][NTf2]). It is understood that PAO base oil refers to polyalphaolefin base oil, including but not limited to PAO 2, PAO 4, PAO 6, PAO 8, mPAO65, mPAO 100, mPAO 150, and other series of PAO base oils. It should be noted that although this invention specification only provides examples of preparing superlubricating microcapsules using a combination of components A and B, component A serves as a solid lubricant and component B as a liquid lubricant. This invention utilizes the synergistic lubrication of solid and liquid lubricants to achieve superlubricity. Components A and B can be selected as needed. Based on the above technical solution, this invention, by using a combination of components A and B as core materials to prepare superlubricating microcapsules, can significantly reduce the coefficient of friction and achieve macroscopic superlubricity in atmospheric environments.

[0051] In some embodiments, the mass of component A is 0.1 to 50 wt% of the total mass of the core material, including but not limited to 33%, and the synergistic effect of component A and component B is more likely to be achieved within this range.

[0052] In some embodiments, the wall material includes one or more of polyimide, polysulfone, polyamide-imide, polyether-imide, polystyrene (PS), urea-formaldehyde resin, and polymethyl methacrylate.

[0053] In some embodiments, the particle size of the super-lubricating microcapsules is 100 nm to 1000 μm; the wall thickness of the super-lubricating microcapsules is 10 nm to 100 μm.

[0054] In the second part, the present invention provides a method for preparing the super-lubricating microcapsules according to any one of the above claims, comprising the following steps:

[0055] 1) Mix component A and component B to obtain the core material;

[0056] 2) The core material and the wall material are mixed and dissolved in an organic solvent to obtain an oil phase;

[0057] 3) The oil phase is added to the aqueous phase consisting of surfactant and water, and the mixture is heated to react and obtain the super-slippery microcapsules.

[0058] In some embodiments, in step 1), the mixing of component A and component B can be specifically performed by ultrasonication at 100 W power for 10 min; in step 2), the mass ratio of the core material to the wall material is 1:(0.067-15), preferably 1:(0.25-2), including but not limited to 1:1.3; the organic solvent can be reasonably selected according to the solubility of the core material and the wall material, for example, the organic solvent is dichloromethane, acetone, ethyl acetate, carbon tetrachloride or petroleum ether.

[0059] In some embodiments, in step 3), the oil phase is added to the aqueous phase under stirring or ultrasonic conditions. The stirring speed of the mechanical stirring is 200 to 2000 rpm, and the ultrasonic power is 50 to 1500 W. When the mechanical stirring speed and ultrasonic power are set within the above ranges, it can ensure that the oil phase and the aqueous phase are uniformly mixed to carry out the emulsification reaction, such as under mechanical stirring conditions of 600 rpm.

[0060] In some embodiments, the surfactant is one or a mixture of several of the following: polyvinyl alcohol, Triton X100, Tween 80, sodium dodecylbenzenesulfonate, ammonium dodecyl sulfate, hexadecyltrimethylammonium bromide, gelatin, gum arabic, and lignin; the concentration of the surfactant in the aqueous phase is 0.05 to 10 wt%; when the mass percentage of the surfactant in the aqueous phase and the volume ratio of the aqueous phase to the oil phase are within the above ranges, a stable oil-in-water (O / W) emulsion can be obtained when it is mixed with the oil phase.

[0061] In some embodiments, the heating temperature is between room temperature and 80°C, and the heating time is between 0.5 and 10 hours; this temperature and time range is more conducive to the formation of microcapsules. The term "room temperature" refers to 15–30°C, preferably 20–25°C, such as 25°C. The heating holding time can specifically be 4 hours.

[0062] It is understood that the method further includes the following post-processing steps: filtering the solution after the reaction, and washing and drying the obtained solid sample sequentially. Optionally, the drying is natural drying at room temperature, oven drying, or freeze drying.

[0063] Thirdly, the present invention provides a superlubricating microcapsule composite material, which is made of any of the superlubricating microcapsules described above and a matrix material having a core-shell structure, wherein the matrix material includes a solid lubricant core material and a polymer shell material covering the core material.

[0064] In some embodiments, the solid lubricant core material may optionally be one or more selected from polyimide, polytetrafluoroethylene (PTFE), graphite, graphene, molybdenum disulfide, boron nitride, polyamide-imide, polyether-imide, tungsten disulfide, black phosphorus, polyetheretherketone, polyphenylene sulfide, fluorinated graphite, silver, and solid paraffin. Alternatively, the polymer shell material may be one or more selected from polyimide, polysulfone, polyamide-imide, polyether-imide, polystyrene, urea-formaldehyde resin, and polymethyl methacrylate.

[0065] In some embodiments, the particle size of the matrix material is 100 nm to 100 μm; the mass fraction of the solid lubricant core material in the matrix material is 5 to 95 wt%.

[0066] In some embodiments, the mass of the superlubricating microcapsule accounts for 0.5 to 50 wt% of the total mass of the superlubricating microcapsule composite material, including but not limited to 50 wt% and 33 wt%.

[0067] Part Four: The present invention provides a method for preparing the super-lubricating microcapsule composite material according to any one of the above claims, comprising the following steps: mixing the super-lubricating microcapsules and the matrix material and then sintering them to obtain the super-lubricating microcapsule composite material.

[0068] In some embodiments, the method for preparing the matrix material includes the following steps:

[0069] 1) The solid lubricant core material is dispersed in water to obtain a core material dispersion;

[0070] 2) Add the precursor and initiator of the polymer shell material to the core material dispersion, and heat under an inert atmosphere to react and obtain the matrix material.

[0071] Further, the concentration of the solid core material dispersion is 1–50 vol%; optionally, the reaction is carried out under stirring or ultrasonic conditions. The stirring speed of mechanical stirring is 200–2000 rpm (e.g., 600 rpm, 800 rpm), and the ultrasonic power is 50–1500 W; the heating temperature is 40–90 °C, and the time is 4–12 hours, such as reacting at 70 °C for 6 hours; the reaction temperature and time are adjusted according to the polymerization reaction of the precursor and initiator under an inert atmosphere. If the temperature is too low, no reaction will occur; if the temperature is too high, the reactants may be damaged. The precursor of the polymer shell material can be reasonably selected according to the polymer shell material. For example, when the polymer shell material is polymethyl methacrylate, methyl methacrylate (MMA) is selected as the shell material, and azobisisobutyronitrile (AIOBR) is selected as the initiator. The proportions of each raw material can be adjusted within a reasonable range according to the particle size and performance requirements. In a specific embodiment of the present invention, the ratio of polymethyl methacrylate concentrated dispersion (PTFE content 60%), methyl methacrylate and azobisisobutyronitrile is 20 mL: 20 mL: 0.5 g or 20 mL: 10 mL: 0.5 g.

[0072] It is understood that the method further includes the following post-processing steps: filtering the solution after the reaction, and washing and drying the obtained solid sample sequentially. The drying process includes room temperature air drying, oven drying, or freeze drying.

[0073] In some embodiments, the sintering step is performed at a pressure of 1–20 MPa and a sintering temperature of 80–300 °C, such as hot pressing at 10 MPa and 100 °C for 30 min.

[0074] The technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0075] Unless otherwise specified, the methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0076] Example 1: Preparation of silicone oil / MoDTC@PS microcapsules and composite materials

[0077] (1) Preparation of silicone oil / MoDTC@PS microcapsules

[0078] S1: Take 2g of silicone oil and 1g of MoDTC, mix them, and sonicate at 100 W for 10 min to obtain microcapsule core material. Mix the core material with 4g of PS (molecular weight 50000) and dissolve it in 50 mL of dichloromethane to obtain the oil phase.

[0079] S2: Take 0.5 g of polyvinyl alcohol (0588 low viscosity type) and add it to 200 mL of deionized water to completely dissolve it to obtain the aqueous phase.

[0080] S3: Transfer the aqueous phase to a three-necked flask, add the oil phase under mechanical stirring at 600 rpm, and keep at room temperature for 4 hours.

[0081] S4: Filter the solution after the reaction, wash the resulting solid sample, and then dry it to obtain silicone oil / MoDTC@PS microcapsules, such as... Figure 1 As shown, the particle size is 100 nm to 1000 μm and the wall thickness is 10 nm to 100 μm.

[0082] (2) Preparation of PTFE@PMMA matrix material

[0083] S1: Take 20 mL of concentrated polytetrafluoroethylene dispersion (PTFE content 60%), add it to 1000 mL of deionized water and transfer it to a four-necked flask, then purge the air from the flask with nitrogen.

[0084] S2: Add 20 mL of methyl methacrylate to a four-necked flask, followed by 0.5 g of azobisisobutyronitrile.

[0085] S3: Set the mechanical stirring speed to 600 rpm and the water bath temperature to 70 ℃ for 6 hours.

[0086] S4: Filter the solution after the reaction, wash the resulting solid sample, and then dry it to obtain the PTFE@PMMA matrix material, such as... Figure 2 As shown, the particle size is 100 nm to 100 μm.

[0087] (3) Preparation of microcapsule composite materials

[0088] S1: The silicone oil / MoDTC@PS microcapsules prepared in (1) and the PTFE@PMMA matrix material prepared in (2) are mechanically mixed in a mass ratio of 1:1 to obtain a mixed powder.

[0089] S2: The mixed powder is hot-pressed and sintered at 10 MPa and 100 ℃ for 30 min to obtain a microcapsule composite material bulk, such as... Figure 3 As shown.

[0090] (4) Tribological property testing of composite materials

[0091] The tribological properties of the composite material were tested on a UMT5 (point contact mode, pressure 15 MPa, speed 6 mm / s). The stable friction coefficient of the microcapsule composite material was 0.008, indicating that it could enter a superlubricated state.

[0092] Example 2: Preparation of silicone oil / MoDTC@PS microcapsules and composite materials

[0093] (1) Preparation of PAO / MoDTC@PS microcapsules

[0094] S1: Take 2g PAO (PAO4, chemical grade) and 1g MoDTC, mix them, and sonicate at 100 W for 10 min to obtain microcapsule core material. Mix the core material with 4g PS (molecular weight 50000) and dissolve it in 50 mL dichloromethane to obtain oil phase.

[0095] S2: Take 0.5 g of polyvinyl alcohol (0588 low viscosity type) and add it to 200 mL of deionized water to completely dissolve it to obtain the aqueous phase.

[0096] S3: Transfer the aqueous phase to a three-necked flask, add the oil phase under mechanical stirring at 600 rpm, and keep at room temperature for 4 hours.

[0097] S4: Filter the solution after the reaction, wash the resulting solid sample, and then dry it to obtain PAO / MoDTC@PS microcapsules, such as... Figure 4 As shown, the particle size is 100 nm to 1000 μm and the wall thickness is 10 nm to 100 μm.

[0098] (2) Preparation of PTFE@PMMA matrix material

[0099] S1: Take 20 mL of concentrated polytetrafluoroethylene dispersion (PTFE content 60%), add it to 1000 mL of deionized water and transfer it to a four-necked flask, then purge the air from the flask with nitrogen.

[0100] S2: Add 10 mL of methyl methacrylate to a four-necked flask, followed by 0.5 g of azobisisobutyronitrile.

[0101] S3: Set the mechanical stirring speed to 800 rpm and heat in a water bath at 70 ℃ for 6 hours.

[0102] S4: Filter the solution after the reaction, wash the obtained solid sample, and then dry it to obtain the PTFE@PMMA matrix material.

[0103] (3) Preparation of microcapsule composite materials

[0104] S1: The microcapsules prepared in (1) and the PTFE@PMMA matrix material prepared in (2) are mechanically mixed at a mass ratio of 1:2 to obtain a mixed powder.

[0105] S2: The mixed powder is hot-pressed and sintered at 10 MPa and 100 ℃ for 30 min to obtain the microcapsule composite material block.

[0106] (4) Tribological property testing of composite materials

[0107] The composite material was subjected to tribological property testing on a UMT5 (point contact mode, pressure 15 MPa, speed 6 mm / s). The change of the friction coefficient over time is shown below. Figure 5 As shown in the results, the friction coefficient of the microcapsule composite material can enter the superlubricated state (stable friction coefficient 0.0062).

[0108] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including modifications made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. A super-lubricating microcapsule composite material, characterized in that, It is made of superlubricating microcapsules and a matrix material with a core-shell structure, wherein the matrix material includes a solid lubricant core and a polymer shell covering the solid lubricant core; The solid lubricant core material is polytetrafluoroethylene; The polymer shell material is polymethyl methacrylate; The super-lubricated microcapsule includes a core material and a wall material covering the core material; The core material includes component A and component B; Component A is molybdenum dialkyldithiocarbamate; Component B is an ionic liquid or a lubricating oil. The ionic liquid includes one or more of the following: 1-butyl-3-methylimidazolium hexafluorophosphate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-octyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. The lubricating oil includes one or more of the following: PAO base oil, linseed oil, alkyl silicone oil, phenyl silicone oil, chain oil, tung oil, mineral oil, ester base oil, liquid paraffin, perfluoropolyether, heavy alkylbenzene, and oleic acid. The wall material includes one or more of polyimide, polysulfone, polyamide-imide, polyether-imide, polystyrene, urea-formaldehyde resin, and polymethyl methacrylate.

2. The super-lubricating microcapsule composite material according to claim 1, characterized in that: The mass of component A is 0.1 to 50 wt% of the total mass of the core material in the super-lubricating microcapsule.

3. The super-lubricating microcapsule composite material according to any one of claims 1-2, characterized in that: The particle size of the super-lubricating microcapsules is 100 nm to 1000 μm; The wall thickness of the super-smooth microcapsules is 10 nm to 100 μm.

4. The super-lubricating microcapsule composite material according to any one of claims 1-2, characterized in that: The method for preparing the super-lubricating microcapsules includes the following steps: 1) Mix component A and component B to obtain the core material; 2) The core material and the wall material are mixed and dissolved in an organic solvent to obtain an oil phase; 3) The oil phase is added to the aqueous phase consisting of surfactant and water, and the mixture is heated to react and obtain the super-slippery microcapsules.

5. The super-lubricating microcapsule composite material according to claim 4, characterized in that: In step 2), the mass ratio of the core material to the wall material is 1:(0.067~15). The organic solvent is dichloromethane, acetone, ethyl acetate, carbon tetrachloride, or petroleum ether; In step 3), the oil phase is added to the aqueous phase under stirring or ultrasonic conditions. The stirring speed of the mechanical stirring is 200-2000 rpm, and the ultrasonic power is 50-1500 W. The surfactant is one or a mixture of several of the following: polyvinyl alcohol, Triton X100, Tween 80, sodium dodecylbenzene sulfonate, ammonium dodecyl sulfate, hexadecyltrimethylammonium bromide, gelatin, gum arabic, and lignin. The concentration of the surfactant in the aqueous phase is 0.05–10 wt%. The heating temperature is between room temperature and 80°C, and the heating time is between 0.5 and 10 hours.

6. The super-lubricating microcapsule composite material according to claim 5, characterized in that: In step 2), the mass ratio of the core material to the wall material is 1:(0.25~2).

7. The super-lubricating microcapsule composite material according to claim 1, characterized in that: The particle size of the matrix material is 100 nm to 100 μm; The solid lubricant core material has a mass fraction of 5–95 wt% in the matrix material with a core-shell structure.

8. The super-lubricating microcapsule composite material according to any one of claims 1-2 and 7, characterized in that: The mass of the super-lubricating microcapsules accounts for 0.5 to 50 wt% of the total mass of the super-lubricating microcapsule composite material.

9. A method for preparing the super-lubricating microcapsule composite material according to any one of claims 1-3 and 7-8, comprising the following steps: mixing the super-lubricating microcapsules and the matrix material and then sintering them to obtain the super-lubricating microcapsule composite material.

10. The method for preparing the superlubricated microcapsule composite material according to claim 9, characterized in that: The method for preparing the matrix material includes the following steps: 1) The solid lubricant core material is dispersed in water to obtain a core material dispersion; 2) Add the precursor and initiator of the polymer shell material to the core material dispersion, and heat under an inert atmosphere to react and obtain the matrix material.

11. The method for preparing the superlubricated microcapsule composite material according to claim 10, characterized in that: The concentration of the core material dispersion is 1–50 vol%. The reaction is carried out under stirring or ultrasonic conditions, with the stirring rate of mechanical stirring being 200–2000 rpm and the ultrasonic power being 50–1500 W. The heating temperature is 40–90 °C, and the heating time is 4–12 hours.

12. The method for preparing the superlubricated microcapsule composite material according to any one of claims 9-11, characterized in that: In the sintering step, the pressure is 1–20 MPa and the sintering temperature is 80–300 °C.

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