CN116083140B

CN116083140B - Self-lubricating microcapsule, preparation method thereof and self-lubricating composite material containing self-lubricating microcapsule

Info

Publication number: CN116083140B
Application number: CN202310148349.9A
Authority: CN
Inventors: 于呈呈; 李肖鹏; 李磊; 祁羽; 李小磊; 伍德民
Original assignee: Ji Hua Laboratory
Current assignee: Ji Hua Laboratory
Priority date: 2023-02-22
Filing date: 2023-02-22
Publication date: 2024-07-12
Anticipated expiration: 2043-02-22
Also published as: CN116083140A

Abstract

The invention provides a self-lubricating microcapsule, a preparation method thereof and a self-lubricating composite material containing the self-lubricating microcapsule. The self-lubricating microcapsule comprises a lubricating core material and a capsule wall coating the lubricating core material; the capsule wall comprises niobium diselenide nanoplatelets and a polymer, wherein the niobium diselenide nanoplatelets are dispersed in the polymer. The self-lubricating microcapsule provided by the invention has good dispersibility and mechanical properties, and can improve the mechanical bearing property of the self-lubricating composite material containing the self-lubricating microcapsule while realizing good friction and lubrication properties.

Description

Self-lubricating microcapsule, preparation method thereof and self-lubricating composite material containing self-lubricating microcapsule

Technical Field

The invention belongs to the technical field of self-lubricating materials, and particularly relates to a self-lubricating microcapsule, a preparation method thereof and a self-lubricating composite material containing the self-lubricating microcapsule.

Background

In the fields of aerospace, mechanical engineering and the like, the problem of friction and abrasion of key parts such as bearings, gears and the like is unavoidable, so that the service life of equipment is shortened, the production capacity is reduced, and even serious safety accidents are caused. Therefore, the research of excellent lubricating and wear-resistant materials has important significance.

The self-lubricating material can provide a continuous lubricating functional material by itself without adding lubricant in the working process, and the lubricant of one of the main components of the material can form a self-lubricating transfer film with low friction, high bearing capacity and long service life at a friction interface in the friction process, thereby achieving the aims of antifriction and wear resistance. The microcapsule technology is a technology which uses inorganic or high polymer materials to coat solid, liquid or gaseous functional materials into solid particles with core-shell structures through physical, chemical and other means, so that the materials in the capsule core are protected, and under the proper conditions of pressurization, heating and the like, the capsule wall is broken, so that the functional materials in the core are released. The lubricant is coated by microcapsule technology and then filled in a polymer matrix, so that the polymer composite material with self-lubricating function can be formed.

The capsule type self-lubricating composite material has remarkable results in the research of the last ten years, but the microcapsule prepared by the prior art can obviously reduce the mechanical property of the composite material when being added into a polymer matrix, and particularly can reduce the bearing property of the self-lubricating composite material. The microcapsule prepared at present has larger particle size, generally in micron order, wider particle size distribution range and poorer dispersion uniformity; on the other hand, the microcapsule has lower mechanical property and is easy to form stress concentration points.

Therefore, a self-lubricating microcapsule with good dispersibility and mechanical properties needs to be researched in the field so as to improve the mechanical bearing property of the self-lubricating composite material.

Disclosure of Invention

Aiming at the defects existing in the prior art, the invention aims to provide a self-lubricating microcapsule, a preparation method thereof and a self-lubricating composite material containing the self-lubricating microcapsule. The self-lubricating microcapsule has good dispersibility and mechanical properties, and can improve the mechanical bearing property of the self-lubricating composite material while realizing good friction and lubrication properties.

To achieve the purpose, the invention adopts the following technical scheme:

In a first aspect, the present invention provides a self-lubricating microcapsule comprising a lubricating core material, and a capsule wall coating the lubricating core material;

The capsule wall comprises niobium diselenide nanoplatelets and a polymer, wherein the niobium diselenide nanoplatelets are dispersed in the polymer.

According to the invention, the niobium diselenide nano-sheets are introduced into the capsule wall of the self-lubricating microcapsule, so that the agglomeration of self-lubricating microcapsule particles can be effectively reduced, and the dispersibility of the self-lubricating microcapsule particles is improved; the mechanical property of the self-lubricating microcapsule particles can be improved, so that the mechanical bearing property of the self-lubricating composite material containing the self-lubricating microcapsule is improved; the friction coefficient of the self-lubricating composite material can be further reduced, and the self-lubricating performance of the self-lubricating composite material can be improved.

In some embodiments of the invention, the lubricating core material is selected from one or more of perfluoro hexanone, octanoic acid, and perfluoro polyether.

In some embodiments of the invention, the number of stacked layers of niobium diselenide nanoplatelets is 1-3.

In some embodiments of the invention, the niobium diselenide nanoplatelets have a diameter of 1 to 200 nm; for example, it may be 1nm, 10nm, 30 nm, 50nm, 80 nm, 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, or the like.

In some embodiments of the invention, the niobium diselenide nanoplatelets are chemically bound to the polymer.

In some embodiments of the invention, the polymer is a copolymer of vinyl caprolactone, 4-acryloylmorpholine and methacrylamide.

In some embodiments of the invention, the niobium diselenide nanoplatelets are present in the capsule wall in an amount of 3 to 13 wt%; for example 3 wt%、3.5wt%、4 wt%、4.5 wt%、5 wt%、5.5 wt%、6 wt%、6.5 wt%、7 wt%、7.5 wt%、8 wt%、8.5 wt%、9 wt%、9.5 wt%、10 wt%、10.5 wt%、11 wt%、11.5 wt%、12 wt%、12.5 wt% or 13 wt%. If the content of the niobium diselenide nano-sheets in the capsule wall is too low, the effect of improving the dispersibility and the mechanical property of the self-lubricating microcapsule is difficult to play, and if the content of the niobium diselenide nano-sheets in the capsule wall is too high, the microcapsule can not be formed effectively.

In some embodiments of the invention, the self-lubricating microcapsule comprises a lubricating core material in an amount of 40-65 wt%; for example, 40 wt%, 42wt%, 45 wt%, 48 wt%, 50 wt%, 52 wt%, 55 wt%, 58 wt%, 60 wt%, 62 wt% or 65 wt% or the like may be used.

In some embodiments of the invention, the self-lubricating microcapsules have a particle size of 80 to 1000 nm; for example, 80 nm, 100nm, 150 nm, 200 nm, 250 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, or the like may be used.

In a second aspect, the present invention provides a method for preparing the self-lubricating microcapsule according to the first aspect, the method comprising the steps of:

(1) Stripping the niobium diselenide two-dimensional lamellar material into niobium diselenide nano-sheets;

(2) Mixing an organic solvent, a lubricating core material and a surfactant to obtain an oil phase; mixing microcapsule wall material monomers, a cross-linking agent, the niobium diselenide nano-sheets and water to obtain a water phase; and adding the oil phase into the water phase in the presence of an initiator to react, so as to generate the self-lubricating microcapsule.

In some embodiments of the invention, the exfoliating niobium diselenide two-dimensional platelet material into niobium diselenide nanoplatelets comprises: dispersing the niobium diselenide two-dimensional lamellar material in an aqueous solution containing organic acid and organic acid salt, carrying out ultrasonic treatment, and then adding an ethanol solution containing polyethylene glycol phosphate and methacrylic acid-2-aminoethyl ester hydrochloride for reaction, so that the niobium diselenide two-dimensional lamellar material is peeled into the niobium diselenide nano-sheet.

In the invention, the niobium diselenide two-dimensional lamellar material is pretreated by utilizing organic acid and organic acid salt, so that the number of hydroxyl groups and cations of the lamellar layer of the two-dimensional lamellar material can be increased, and the interface interaction between the modifier (polyethylene glycol phosphate and methacrylic acid-2-aminoethyl ester hydrochloride) and the lamellar layer is enhanced; polyethylene glycol phosphate and methacrylic acid-2-aminoethyl ester hydrochloride are matched, and the polyethylene glycol phosphate and methacrylic acid-2-aminoethyl ester hydrochloride enter between two-dimensional lamellar material layers through hydrogen bonding and cation exchange reaction intercalation, so that lamellar spacing is increased, interaction force between lamellar layers is weakened, stripping time of the two-dimensional lamellar material can be obviously shortened, and stripping rate is improved. After being stripped by the method, the niobium diselenide nano-sheets with the stacking layer number of 1-3 can be obtained. Wherein, methacrylic acid-2-amino ethyl ester hydrochloride can also be connected to the niobium diselenide nano-sheet, and reacts with microcapsule wall material monomer during the polymerization reaction in the step (2), so that the niobium diselenide nano-sheet and the capsule wall polymer realize firm chemical bonding.

In some embodiments of the invention, the organic acid is selected from one or more of formic acid, acetic acid, propionic acid, and butyric acid.

In some embodiments of the invention, the organic acid salt is selected from one or more of sodium formate, sodium acetate, sodium propionate, and sodium butyrate.

In some embodiments of the invention, the mass ratio of the organic acid to the organic acid salt is 1:1-4; for example, it may be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, or 1:4, etc.

In some embodiments of the invention, the mass ratio of the organic acid and organic acid salt to the niobium diselenide two-dimensional platelet material is 2-7:1; for example, it may be 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, or 7:1, etc.

In some embodiments of the invention, the mass ratio of the aqueous solution containing the organic acid and the organic acid salt to the niobium diselenide two-dimensional lamellar material is 10-50:1; for example, it may be 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, or 50:1, etc.

In some embodiments of the invention, the time of the sonication is from 1 to 10 min; for example, it may be 1 min, 2min, 3 min, 4 min, 5 min, 6 min, 7 min, 8min, 9 min, 10 min, or the like.

In some embodiments of the invention, the mass ratio of the polyethylene glycol phosphate to the 2-aminoethyl methacrylate hydrochloride is 1-5:1; for example, it may be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, or 5:1, etc.

In some embodiments of the present invention, in the ethanol solution containing polyethylene glycol phosphate and methacrylic acid-2-aminoethyl ester hydrochloride, the mass of polyethylene glycol phosphate is 15-30% of the mass of ethanol, and the mass of methacrylic acid-2-aminoethyl ester hydrochloride is 6-15% of the mass of ethanol.

In some embodiments of the invention, the mass ratio of the polyethylene glycol phosphate and 2-aminoethyl methacrylate hydrochloride to the niobium diselenide two-dimensional platelet material is 0.5-5:1; for example, it may be 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, or 5:1, etc.

In some embodiments of the invention, the ethanol solution containing polyethylene glycol phosphate and 2-aminoethyl methacrylate hydrochloride is added dropwise.

In some embodiments of the invention, the adding an ethanol solution comprising polyethylene glycol phosphate and 2-aminoethyl methacrylate hydrochloride is performed under stirring conditions, the stirring speed being 100-300 rpm; for example, it may be 100 rpm, 120rpm, 150rpm, 180 rpm, 200 rpm, 220 rpm, 250 rpm, 280 rpm, 300 rpm, or the like.

In some embodiments of the invention, the reaction time for adding the ethanol solution containing polyethylene glycol phosphate and 2-aminoethyl methacrylate hydrochloride is 1-5 min; for example, it may be 1 min, 1.5min, 2 min, 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min or 5min, etc.

In some embodiments of the invention, the exfoliating the niobium diselenide two-dimensional platelet material into niobium diselenide nanoplatelets further comprises: after the reaction is finished, separating a solid product, and washing, drying, grinding and sieving to obtain the niobium diselenide nano-sheet.

In some embodiments of the invention, the organic solvent is selected from one or more of cyclohexane, cyclopentane, cycloheptane, and n-hexane.

In some embodiments of the invention, the surfactant is selected from one or more of sucrose esters, cocobetaine, and sodium stearoyl lactylate.

In some embodiments of the invention, the mass ratio of the organic solvent, the lubricating core material and the surfactant in the oil phase is 1 (0.5-3): 0.01-0.05. Wherein the mass of the lubricating core material relative to the organic solvent may be 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, or the like, based on the mass of the organic solvent being 1; the mass of the surfactant with respect to the organic solvent may be 0.01, 0.02, 0.03, 0.04, 0.05, or the like.

In some embodiments of the invention, the microcapsule wall monomers are carbon-carbon double bond containing monomers. Preferably, the microcapsule wall material monomer consists of vinyl caprolactone, 4-acryloylmorpholine and methacrylamide in a mass ratio of 1 (0.5-3) to 0.8-6. Wherein the mass ratio of the 4-acryloyl morpholine to the vinyl caprolactone can be 0.5:1, 0.8:1, 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 2.8:1, 3:1 or the like; the mass ratio of the methacrylamide to the vinyl caprolactone can be 0.8:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, or 6:1, etc.

In the invention, vinyl caprolactone, 4-acryloylmorpholine and methacrylamide are adopted as main monomers for synthesizing the capsule wall polymer, and the three are matched, so that the formed polymer has good mechanical properties on one hand, and is beneficial to further improving the mechanical properties of the capsule wall; on the other hand, the adsorption of the niobium diselenide nano-sheets is facilitated, and the formation of self-lubricating microcapsules is facilitated; in addition, the interfacial interaction between the microcapsule and the matrix such as polyester resin, epoxy resin and the like can be improved, and the mechanical bearing property of the self-lubricating composite material can be improved.

In some embodiments of the invention, the crosslinker is N, N-methylenebisacrylamide.

In some embodiments of the invention, the mass ratio of the microcapsule wall material monomer, the cross-linking agent, the niobium diselenide nano-sheets and the water in the water phase is 1 (0.01-0.1): 0.05-0.15): 10-40. Wherein the cross-linking agent may be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc. based on the mass of the microcapsule wall material monomer being 1; the mass of the niobium diselenide nano-sheet relative to the microcapsule wall material monomer can be 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14 or 0.15 and the like; the mass of the water relative to the microcapsule wall material monomer can be 10, 15, 20, 25, 30, 35 or 40, etc.

In some embodiments of the invention, the ratio of the mass of the lubricating core material to the total mass of the microcapsule wall material monomer, cross-linking agent and niobium diselenide nanoplatelets is 1:1-3; for example, it may be 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.2, 1:2.5, 1:2.8, or 1:3, etc. Preferably 1:1-2.

In some embodiments of the invention, the initiator is potassium persulfate.

In some embodiments of the invention, the initiator is used in an amount of 0.1 to 0.3% by mass of the microcapsule wall monomer; for example, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.22%, 0.25%, 0.28%, or 0.3% may be used.

In some embodiments of the invention, the temperature of the reaction in step (2) is 50-80 ℃, e.g., 50 ℃,52 ℃, 55 ℃, 58 ℃, 60 ℃, 62 ℃, 65 ℃, 68 ℃,70 ℃, 72 ℃, 75 ℃, 78 ℃, or 80 ℃, etc.; the time is 4-8 h, and can be, for example, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8h, etc.

In some embodiments of the invention, the reaction in step (2) is performed in a protective atmosphere.

In some embodiments of the invention, the reaction in step (2) is carried out under stirring conditions, the stirring being at a rate of 1000 to 2000 rpm; for example, 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, 1600 rpm, 1700 rpm, 1800 rpm, 1900 rpm, or 2000 rpm, etc.

In some embodiments of the invention, the method of preparing further comprises: after the reaction in the step (2) is finished, separating a solid product, washing and drying to obtain the self-lubricating microcapsule.

In a third aspect, the present invention provides a self-lubricating composite material comprising the self-lubricating microcapsules of the first aspect, and a polymer matrix.

In some embodiments of the invention, the self-lubricating microcapsules are present in the self-lubricating composite material in an amount of 2 to 40 wt%; for example 2 wt%、3wt%、5 wt%、8 wt%、10 wt%、12 wt%、15 wt%、18 wt%、20 wt%、22 wt%、25 wt%、28 wt%、30 wt%、32 wt%、35 wt%、38 wt% or 40 wt%, etc.

In some embodiments of the invention, the polymer matrix is selected from one or more of unsaturated polyesters, polyurethanes, acrylate resins, and epoxy resins.

Compared with the prior art, the invention has the following beneficial effects:

According to the invention, the niobium diselenide nano-sheets are introduced into the capsule wall of the self-lubricating microcapsule, so that on one hand, the agglomeration of self-lubricating microcapsule particles can be effectively reduced, and the dispersibility of the self-lubricating microcapsule particles is improved; on the other hand, the mechanical property of the self-lubricating microcapsule particles can be improved. The self-lubricating composite material containing the self-lubricating microcapsule has good mechanical bearing, antifriction and wear-resisting properties.

Drawings

FIG. 1 is a transmission electron microscope image of niobium diselenide nanoplatelets obtained in preparation example 1;

FIG. 2 is a scanning electron microscope image of the self-lubricating microcapsules provided in example 1;

fig. 3 is a graph showing the compressive strength test of a composite material containing self-lubricating microcapsules provided in example 1 and comparative example 1 and an unsaturated polyester resin.

Detailed Description

The technical scheme of the invention is further described below by the specific embodiments with reference to the accompanying drawings. It should be apparent to those skilled in the art that the detailed description is merely provided to aid in understanding the invention and should not be taken as limiting the invention in any way.

Preparation example 1

Preparation of niobium diselenide nanosheets:

dissolving formic acid 10 g and sodium formate 10 g in deionized water 100 mL, adding niobium diselenide two-dimensional lamellar material 10 g, and carrying out ultrasonic treatment at normal temperature for 10min to obtain a two-dimensional lamellar material dispersion;

polyethylene glycol phosphate 4 g and methacrylic acid-2-aminoethyl ester hydrochloride 1 g are dissolved in ethanol 15g to obtain a modifier solution;

dripping the modifier solution into the two-dimensional lamellar material dispersion liquid, and finishing 2 min drops; reacting 1.1 min at normal temperature under the stirring rate of 300 rpm; and after the reaction is finished, centrifuging at a high speed, carrying out vacuum suction filtration, leaching a solid product by using absolute ethyl alcohol and deionized water, carrying out vacuum drying, grinding and sieving to obtain the niobium diselenide nano-sheet.

The morphology of the niobium diselenide nano-sheet obtained in the preparation example is characterized by adopting a transmission electron microscope, and the result is shown in figure 1; it can be seen that the niobium diselenide nano-sheets are successfully peeled off, and the stacking layer number is 1-3. The D50 particle size of the niobium diselenide nano-sheet obtained in the preparation example is measured to be 113nm by adopting a Markov dynamic light scattering analyzer.

Preparation example 2

Preparation of niobium diselenide nanosheets:

Dissolving acetic acid 15 g and sodium acetate 30g in deionized water 200 mL, adding niobium diselenide two-dimensional lamellar material 10 g, and carrying out ultrasonic treatment at normal temperature for 10min to obtain a two-dimensional lamellar material dispersion;

polyethylene glycol phosphate 10g and methacrylic acid-2-aminoethyl ester hydrochloride 10g were dissolved in 66g of ethanol to give a modifier solution;

Dripping the modifier solution into the two-dimensional lamellar material dispersion liquid, and finishing 5min drops; reacting 5min at normal temperature under the stirring rate of 100 rpm; and after the reaction is finished, centrifuging at a high speed, carrying out vacuum suction filtration, leaching a solid product by using absolute ethyl alcohol and deionized water, carrying out vacuum drying, grinding and sieving to obtain the niobium diselenide nano-sheet.

The D50 particle size of the niobium diselenide nano-sheet obtained in the preparation example is 94nm by using a Markov dynamic light scattering analyzer.

Preparation example 3

Preparation of niobium diselenide nanosheets:

dissolving 18 g of propionic acid and 62 g of sodium propionate in 500 mL of deionized water, adding 10 g of niobium diselenide two-dimensional lamellar material, and carrying out ultrasonic treatment at normal temperature for 10min to obtain a two-dimensional lamellar material dispersion;

Polyethylene glycol phosphate 33 g and methacrylic acid-2-aminoethyl ester hydrochloride 17 g were dissolved in 120g of ethanol to give a modifier solution;

dripping the modifier solution into the two-dimensional lamellar material dispersion liquid, and finishing 3 min drops; reacting at normal temperature under the stirring rate of 200 rpm for 2 min; and after the reaction is finished, centrifuging at a high speed, carrying out vacuum suction filtration, leaching a solid product by using absolute ethyl alcohol and deionized water, carrying out vacuum drying, grinding and sieving to obtain the niobium diselenide nano-sheet.

The D50 particle size of the niobium diselenide nano-sheet obtained in the preparation example is 149nm by using a Markov dynamic light scattering analyzer.

Preparation example 4

Preparation of niobium diselenide nanosheets:

the only difference from preparation 1 is that polyethylene glycol phosphate is replaced with equal mass of 2-aminoethyl methacrylate hydrochloride.

The D50 particle size of the niobium diselenide nano-sheet obtained in the preparation example is 1532nm measured by a Markov dynamic light scattering analyzer, which indicates that the niobium diselenide nano-sheet is of an intercalation type block aggregation structure, and the exfoliated niobium diselenide nano-sheet is not obtained.

Example 1

The embodiment provides a self-lubricating microcapsule, which is prepared by the following steps:

uniformly mixing cyclohexane 8 g, perfluoro hexanone 4 g and sucrose ester 0.08 and g to obtain an oil phase;

2g of vinyl caprolactone, 1 g of 4-acryloylmorpholine, 1.6 g of methacrylamide, 0.05 g of N, N-methylene bisacrylamide, 0.46 g of niobium diselenide nano-sheet obtained in preparation example 1 and 180 mL of deionized water are mixed to obtain a water phase;

Dropwise adding the oil phase into the water phase in a nitrogen atmosphere, and simultaneously dropwise adding 20 wt% of potassium persulfate aqueous solution (containing potassium persulfate 0.005 g) and 5 min; and (3) reacting 8h at the temperature of 80 ℃ and the stirring rotation speed of 1500 rpm, filtering a solid product after the reaction is finished, washing and drying to obtain the self-lubricating microcapsule.

The morphology of the self-lubricating microcapsule obtained in this example was characterized by using a scanning electron microscope, and the result is shown in fig. 2; it can be seen that the self-lubricating microcapsule has a core-shell structure, and niobium diselenide nano-sheets are dispersed on the capsule wall.

Example 2

uniformly mixing cyclopentane 2 g, octanoic acid 6 g and cocobetaine 0.1 and g to obtain an oil phase;

Mixing 0.7g of vinyl caprolactone, 2.1 g of 4-acryloylmorpholine, 4.2 g of methacrylamide, 0.7g of N, N-methylenebisacrylamide, 0.35 g of niobium diselenide nano-sheet obtained in preparation example 1 and 70 mL of deionized water to obtain a water phase;

dropwise adding the oil phase into the water phase in a nitrogen atmosphere, and simultaneously dropwise adding a 20 wt% potassium persulfate aqueous solution (containing potassium persulfate 0.02 g) for 10 minutes; and (3) reacting 6 h at the temperature of 75 ℃ and the stirring rotation speed of 2000 rpm, filtering a solid product after the reaction is finished, washing and drying to obtain the self-lubricating microcapsule.

Example 3

Uniformly mixing cycloheptane 2 g, perfluoropolyether 3 g and sodium stearoyl lactylate 0.04 and g to obtain an oil phase;

Mixing 0.5g of vinyl caprolactone, 1 g g of 4-acryloylmorpholine, 2.5 g g of methacrylamide, 0.2 g g of N, N-methylenebisacrylamide, 0.6g g of niobium diselenide nano-sheet obtained in preparation example 3 and 120 mL g of deionized water to obtain a water phase;

Dropwise adding the oil phase into the water phase in a nitrogen atmosphere, and simultaneously dropwise adding a 20wt% potassium persulfate aqueous solution (containing potassium persulfate 0.01 g) for 3 min; and (3) reacting 7 h at 50 ℃ and stirring speed of 1000 rpm, filtering a solid product after the reaction is finished, washing and drying to obtain the self-lubricating microcapsule.

Example 4

uniformly mixing n-hexane 3 g, octanoic acid 5g and sucrose ester 0.09 and g to obtain an oil phase;

Mixing 0.9g of vinyl caprolactone, 1.5 g of 4-acryloylmorpholine, 2.9 g of methacrylamide, 0.18 g of N, N-methylenebisacrylamide, 0.63 g of niobium diselenide nano-sheet obtained in preparation example 1 and 160 mL of deionized water to obtain a water phase;

Dropwise adding the oil phase into the water phase in a nitrogen atmosphere, and simultaneously dropwise adding 20 wt% of potassium persulfate aqueous solution (containing potassium persulfate 0.015 g) and 7 min; reacting at 62 ℃ under the condition of stirring rotation speed of 1300 rpm for 4h, filtering a solid product after the reaction is finished, washing and drying to obtain the self-lubricating microcapsule.

Example 5

This example provides a self-lubricating microcapsule differing from example 1 only in that vinyl caprolactone 2 g, 4-acryloylmorpholine 1g and methacrylamide 1.6 g are replaced with 4-acryloylmorpholine 2 g and methacrylamide 2.6 g.

Example 6

This example provides a self-lubricating microcapsule differing from example 1 only in that vinyl caprolactone 2 g, 4-acryloylmorpholine 1 g and methacrylamide 1.6 g are replaced by vinyl caprolactone 2.5 g and 4-acryloylmorpholine 2.1 g.

Comparative example 1

This comparative example provides a self-lubricating microcapsule differing from example 1 only in that no niobium diselenide nanoplatelets were added.

Comparative example 2

This comparative example provides a self-lubricating microcapsule differing from example 1 only in that niobium diselenide nanoplatelets were replaced with graphene oxide (average diameter 164 nm).

Comparative example 3

This comparative example provides a self-lubricating microcapsule differing from example 1 only in that niobium diselenide nanoplatelets are replaced with silica particles (D50 particle size 150 nm).

Comparative example 4

This comparative example provides a self-lubricating microcapsule differing from example 1 only in that niobium diselenide nanoplatelets were replaced with titanium dioxide particles (D50 particle size 70 nm).

The self-lubricating microcapsules provided in the above examples and comparative examples, the curing agent methyl ethyl ketone peroxide-cobalt iso-octoate and the unsaturated polyester resin (mark 901 of Shanghai fine chemical Co., ltd.) were uniformly mixed and cured at 80℃for 3 h to obtain a self-lubricating composite material, wherein the amount of the self-lubricating microcapsules is 10% of the mass of the self-lubricating composite material. Meanwhile, unsaturated polyester resin without self-lubricating microcapsules was used as a comparison.

Performance test:

the self-lubricating microcapsules provided in the above examples and comparative examples, and the prepared self-lubricating composite materials were tested for performance by the following test methods:

Particle size and polydispersity: diluting the prepared sample to be tested with a certain deionized water, performing ultrasonic dispersion at room temperature for 10min times, and performing room temperature test on the average particle size and the polydispersity of the self-lubricating microcapsule by using a Markov dynamic light scattering analyzer (Malvern Mastersizer 2000), performing parallel test on the same sample for 3 times, and taking an average value.

Core material content, niobium diselenide nano-sheet content in capsule wall: and (3) testing the core material content of the microcapsule sample and the content of the niobium diselenide nano-sheets in the capsule wall by adopting a comprehensive thermal analyzer (STA 409 PC), wherein the temperature rising rate is 10 ℃/min, and the temperature range is 25-800 ℃.

Coefficient of friction of self-lubricating composite: the prepared composite was characterized for tribological properties using a multifunctional frictional wear tester (UMT-3, brucker), employing a ball-and-disk contact reciprocation mode. Wherein, the Shanghai steel ball mill produces small balls (surface roughness about 5 nm) with the diameter of 4.6 mmGCr15 bearing steel as a counter grinding pair, the reciprocating distance is 4.5mm, and the test is carried out for 60min under certain reciprocating frequency and load conditions. Before experimental test, the steel ball is immersed in absolute ethyl alcohol for ultrasonic cleaning for 20 min to remove stains on the surface of the steel ball. Each sample was tested three times under the same conditions and the results averaged.

Self-lubricating composite compression strength: the compression strength test of the resin matrix composite material is carried out by an Instron-1121 universal material tester according to GB/T2569-1995 method for testing compression Property of resin casting body. The compression rate was 1 mm/min, the number of each test bar was 9, and the results were averaged.

The results of the above performance tests are shown in table 1 below:

TABLE 1

Group of	Particle size (nm)	Polydisperse coefficient	Core content (%)	Niobium diselenide nanosheet content in capsule wall (%)	Coefficient of friction	Compressive Strength (MPa)
							Example 1	415	0.105	65.0	9.3	0.012	145.5
Example 2	382	0.129	58.1	5.0	0.020	172.6
							Example 3	624	0.124	63.5	12.1	0.047	158.9
Example 4	878	0.143	55.4	10.7	0.033	155.4
							Example 5	1034	0.204	40.2	3.4	0.121	99.4
Example 6	1167	0.188	41.5	3.9	0.146	98.7
							Comparative example 1	3439	0.237	35.0	/	0.281	45.3
Comparative example 2	1846	0.214	39.4	/	0.197	66.7
							Comparative example 3	2757	0.230	37.6	/	0.258	58.0
Comparative example 4	2548	0.225	36.5	/	0.240	60.4
							Polyester resin	/	/	/	/	0.649	96.4

The compression strength test graphs of the composite material containing the self-lubricating microcapsules of example 1, the composite material containing the self-lubricating microcapsules of comparative example 1, and the unsaturated polyester resin are shown in fig. 3.

From the test results of table 1 and fig. 3, it can be seen that the self-lubricating composite material containing the self-lubricating microcapsules provided by the present invention has a lower friction coefficient and a higher compressive strength.

Among them, in example 5 and example 6, only two of vinyl caprolactone, 4-acryloylmorpholine and methacrylamide were used as microcapsule wall material monomers, so that the mechanical properties of the self-lubricating microcapsules were reduced, the compression strength of the self-lubricating composite materials was reduced, and the friction coefficient was increased.

Compared with example 1, comparative examples 1-4 all resulted in an increase in the coefficient of friction of the self-lubricating microcapsules and a significant decrease in the mechanical properties (lower than pure resin) due to the absence of niobium diselenide nanoplatelets or the use of other materials instead of niobium diselenide nanoplatelets, which in turn resulted in a significant decrease in the compressive strength of the self-lubricating composite.

The foregoing is merely a specific embodiment of the disclosure to enable one skilled in the art to understand or practice the disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown and described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A self-lubricating microcapsule, characterized in that the self-lubricating microcapsule comprises a lubricating core material and a capsule wall coating the lubricating core material;

the capsule wall comprises niobium diselenide nano-sheets and a polymer, wherein the niobium diselenide nano-sheets are dispersed in the polymer;

The polymer is a polymerization product of microcapsule wall material monomers; the number of stacked layers of the niobium diselenide nano-sheets is 1-3, and the diameter of the niobium diselenide nano-sheets is 1-200 nm;

The preparation method of the self-lubricating microcapsule comprises the following steps:

(2) Mixing an organic solvent, a lubricating core material and a surfactant to obtain an oil phase; mixing microcapsule wall material monomers, a cross-linking agent, the niobium diselenide nano-sheets and water to obtain a water phase; adding the oil phase into the water phase in the presence of an initiator to react to generate the self-lubricating microcapsule;

The mass ratio of the organic solvent to the lubricating core material to the surfactant in the oil phase is 1 (0.5-3) (0.01-0.05);

The microcapsule wall material monomer consists of vinyl caprolactone, 4-acryloylmorpholine and methacrylamide in a mass ratio of 1 (0.5-3) to 0.8-6;

the cross-linking agent is N, N-methylene bisacrylamide;

The mass ratio of the microcapsule wall material monomer, the cross-linking agent, the niobium diselenide nano-sheet and the water in the water phase is 1 (0.01-0.1) (0.05-0.15) (10-40);

the temperature of the reaction in the step (2) is 50-80 ℃ and the time is 4-8 h.

2. The self-lubricating microcapsule according to claim 1, wherein the lubricating core material is selected from one or more of the group consisting of perfluoro hexanone, octanoic acid and perfluoro polyether;

And/or, a chemical bond between the niobium diselenide nanoplatelets and the polymer;

And/or the content of the niobium diselenide nano-sheets in the capsule wall is 3-13 wt%;

and/or the content of the lubricating core material in the self-lubricating microcapsule is 40-65 wt%;

and/or the particle size of the self-lubricating microcapsule is 80-1000 nm.

3. A method of preparing the self-lubricating microcapsules of claim 1 or 2, comprising the steps of:

the cross-linking agent is N, N-methylene bisacrylamide;

4. The method of claim 3, wherein the stripping of the niobium diselenide two-dimensional platelet material into niobium diselenide nanoplatelets comprises: dispersing the niobium diselenide two-dimensional lamellar material in an aqueous solution containing organic acid and organic acid salt, carrying out ultrasonic treatment, and then adding an ethanol solution containing polyethylene glycol phosphate and methacrylic acid-2-aminoethyl ester hydrochloride for reaction, so that the niobium diselenide two-dimensional lamellar material is peeled into the niobium diselenide nano-sheet.

5. The method according to claim 4, wherein the organic acid is selected from one or more of formic acid, acetic acid, propionic acid, and butyric acid;

and/or the organic acid salt is selected from one or more of sodium formate, sodium acetate, sodium propionate and sodium butyrate;

And/or the mass ratio of the organic acid to the organic acid salt is 1:1-4;

and/or the mass ratio of the organic acid and the organic acid salt to the niobium diselenide two-dimensional lamellar material is 2-7:1;

And/or the mass ratio of the aqueous solution containing the organic acid and the organic acid salt to the niobium diselenide two-dimensional lamellar material is 10-50:1;

and/or the mass ratio of the polyethylene glycol phosphate to the methacrylic acid-2-aminoethyl ester hydrochloride is 1-5:1;

and/or the mass ratio of the polyethylene glycol phosphate to the methacrylic acid-2-amino ethyl ester hydrochloride to the niobium diselenide two-dimensional lamellar material is 0.5-5:1;

And/or the time of the ultrasonic treatment is 1-10 min;

And/or adding an ethanol solution containing polyethylene glycol phosphate and methacrylic acid-2-amino ethyl ester hydrochloride to react under stirring, wherein the stirring speed is 100-300 rpm;

and/or adding an ethanol solution containing polyethylene glycol phosphate and methacrylic acid-2-amino ethyl ester hydrochloride for reaction for a reaction time of 1-5 min;

and/or, the peeling of the niobium diselenide two-dimensional lamellar material into niobium diselenide nano-sheets further comprises: after the reaction is finished, separating a solid product, and washing, drying, grinding and sieving to obtain the niobium diselenide nano-sheet.

6. A method of preparation according to claim 3, wherein the organic solvent is selected from one or more of cyclohexane, cyclopentane, cycloheptane and n-hexane;

And/or the surfactant is selected from one or more of sucrose ester, cocobetaine and sodium stearoyl lactylate;

And/or the ratio of the mass of the lubricating core material to the total mass of the microcapsule wall material monomer, the cross-linking agent and the niobium diselenide nano-sheet is 1:1-3;

And/or, the initiator is potassium persulfate;

And/or the initiator is used in an amount of 0.1-0.3% of the mass of the microcapsule wall material monomer.

7. The method of claim 6, wherein the ratio of the mass of the lubricating core material to the total mass of the microcapsule wall material monomer, cross-linking agent, and niobium diselenide nanoplatelets is 1:1-2.

8. A production method according to claim 3, wherein the reaction in step (2) is carried out in a protective atmosphere;

and/or, the reaction in the step (2) is carried out under stirring conditions, wherein the stirring speed is 1000-2000 rpm;

And/or, the preparation method further comprises: after the reaction in the step (2) is finished, separating a solid product, washing and drying to obtain the self-lubricating microcapsule.

9. A self-lubricating composite material, characterized in that it comprises the self-lubricating microcapsules according to claim 1 or 2, and a polymeric matrix.

10. The self-lubricating composite material according to claim 9, wherein the self-lubricating microcapsules are present in the self-lubricating composite material in an amount of 2-40 wt%;

and/or the polymer matrix is selected from one or more of unsaturated polyester, polyurethane, acrylate resin and epoxy resin.