An oleic acid-modified borate / polydopamine / talc nanocomposite material, its preparation method and application

Abstract

This invention discloses an oleic acid-modified borate / polydopamine / talc nanocomposite material, its preparation method, and its applications, belonging to the field of nanocomposite material technology. This invention uses polydopamine as a bridging agent to bond borate nanoparticles to the surface and interlayer of talc sheets. Oleic acid is then grafted onto the resulting borate / polydopamine / talc nanocomposite material to prepare the oleic acid-modified borate / polydopamine / talc nanocomposite material. The composite material of this invention has a water contact angle of 143–145°. When used as a lubricating oil additive in base oils, it requires a small addition amount and provides significant lubrication effects. It exhibits excellent dispersion stability in base oils and can effectively improve the tribological and antioxidant properties of the base oils. The preparation method of this invention uses safe, environmentally friendly, and pollution-free raw materials. The preparation process is simple, with low production costs. The resulting composite material has broad economic and social benefits and is worthy of large-scale promotion and application.

Description

Technical Field

[0001] This invention belongs to the field of nanocomposite materials technology, specifically relating to an oleic acid-modified borate / polydopamine / talc nanocomposite material, its preparation method, and its application. Background Technology

[0002] Friction and wear are reportedly responsible for a quarter of global energy losses. This is because frictional resistance generated during the relative movement of components causes the consumption of mechanical energy, which is converted into heat, resulting in wear on the contact surfaces. Therefore, research on reducing friction and wear is essential. Nanomaterials are widely used in tribology due to their unique thermal and mechanical properties and small size effect. Nano-borates have the advantages of being non-toxic, environmentally friendly, and low-cost. Due to their unique antioxidant stability, rust and corrosion prevention, sealing adaptability, mechanical properties, and small size effect, they have attracted widespread attention as lubricant additives. CN108485753A discloses a graphene-based nano-borate lubricant and its preparation method. This method combines graphene with nano-borate to obtain graphene-based nano-borates. Introducing borate groups onto graphene can improve the dispersibility and anti-wear properties of graphene, thus making it suitable as an anti-wear material for lubricants.

[0003] Borates can induce chemical reactions under friction, thereby forming a self-healing protective film rich in boron trioxide, iron oxide, and iron boride on the friction contact surface. Boron is a non-reactive extreme pressure anti-wear element; it does not corrode metals, but its adsorption to metal surfaces is poor, requiring substances containing active groups to rapidly bring boron to the metal surface. Talc is a two-dimensional layered silicate mineral composed of an octahedral magnesium hydroxide layer sandwiched between two tetrahedral silica layers. Due to its novel electrochemical, catalytic, thermal, and mechanical properties, it has attracted considerable interest over the past decade. Therefore, in the field of tribology, talc and its derivatives have been found to be excellent solid lubricants or nano-additives in water / oil-based lubricants. The surface of talc contains numerous unsaturated or dangling bonds such as Si-O-Si, O-Si-O, Mg-O / -OH, and hydrogen bonds, exhibiting strong physicochemical activity and polarity. During friction, it has a high affinity for the friction pair surface, rapidly forming a tribochemical reaction film and thus possessing unique tribological properties. Furthermore, talc powder, due to its softness and tendency to break into flakes, often exhibits poor extreme pressure performance. Therefore, combining talc powder with nano-borate can achieve a synergistic lubrication effect, with talc powder carrying borate to the friction pair surface, while borate exerts its extreme pressure anti-friction properties.

[0004] However, the hydrophobic properties of talc surface result in few binding sites with other substances, making the composite of inert borates with talc a challenge. Polydopamine (PDA) possesses excellent adhesive properties due to its abundant phenolic hydroxyl and amino active functional groups, which can form hydrogen bonds with most inorganic substances, thus bonding them together. Therefore, it has wide applications in the preparation of composite materials as lubricant additives. Patent publication number CN 113861679A discloses a polydopamine nanosphere / boron nitride quantum dot / graphene solid lubricant, its preparation method, applications, and composite materials. The polydopamine in this lubricant exhibits strong interfacial adhesion, which can improve the adhesion between graphene and boron nitride quantum dots, while also enhancing the interfacial interaction and compatibility between graphene and boron nitride quantum dots and the polymer matrix. The solid lubricant obtained by this method can reduce and stabilize the coefficient of friction of the matrix material and improve its wear resistance.

[0005] Furthermore, PDA exhibits strong chemical bonding with the iron-based friction pair surface, and under the influence of tribochemical effects, it is adsorbed onto the friction contact area, rapidly forming Fe-OC bonds with the oxide layer through further chelation. However, borates are ionic minerals, which can rapidly precipitate upon contact with anions and cations, easily forming large, irregularly shaped crystals and leading to severe agglomeration. Their morphology and size are difficult to regulate through technical conditions. Ostwald ripening is a process in which small crystals redissolve under thermodynamic drive and regrow on the outer surface of larger crystals. Therefore, the particle size regrowth of ZB can be controlled during the high-temperature reaction. Furthermore, intercalation can be achieved by simply mixing two-dimensional layered crystals with a solution containing selected intercalants, which can be attributed to the increased interlayer spacing at high temperatures. Simultaneously, under thermodynamic drive, PDA can uniformly adhere to the talc surface and interlayer. In addition, intercalation methods can be classified into polymerization intercalation, solution intercalation, and melt intercalation. The polymerization intercalation method involves inserting organic monomers into the interlayer space of an inorganic material with a layered structure, then initiating in-situ polymerization of the monomers within the interlayer space. During polymerization, the interlayer spacing of the inorganic phases increases or even peels off, resulting in an organic-inorganic nanocomposite material. Therefore, driven by thermodynamics, it is expected to utilize the abundant phenolic hydroxyl and nitrogen-containing groups in the PDA structure as intermediate bridges for chelating metal ions to achieve uniform growth of borate on the surface and between layers of talc and rapid self-polymerization of PDA. In summary, the uniform growth of borate can be regulated by the anchoring effect of PDA, effectively solving the problem of easy agglomeration of borate nanoparticles due to their high surface energy.

[0006] However, the thickness of two-dimensional layered materials affects their tribological properties, as the increased contact area and thickness make it difficult for the material to penetrate the friction pair surface. Currently, most methods for exfoliating two-dimensional materials employ electrochemical exfoliation, ultrasonic exfoliation, and ball milling exfoliation. Among these, ball milling exfoliation has advantages such as low cost, environmental friendliness, and ease of operation, and has great potential for practical application. Therefore, to fully utilize the advantages of talc and borate, this invention adopts the Ostwald curing strategy to design an intercalated nanocomposite material, and uses mechanical ball milling to exfoliate and hydrophobically modify the nanocomposite material to improve its tribological properties. Summary of the Invention

[0007] To address the above problems, this invention provides an oleic acid-modified borate / polydopamine / talc nanocomposite material, its preparation method, and its application. By using polydopamine as an intermediate bridge, borate nanoparticles are uniformly anchored on the surface of talc, and oleic acid is further introduced into the material, which can effectively solve the problem of easy agglomeration of borate materials. The resulting composite material is used as a lubricating oil additive, which has good dispersion stability in base oil and can effectively improve the tribological properties of base oil.

[0008] This invention is achieved through the following technical solution:

[0009] An oleic acid-modified borate / polydopamine / talc nanocomposite material is disclosed. Using polydopamine as a bridging agent, borate nanoparticles are first bonded to the surface and interlayer of talc sheets via polydopamine to obtain the borate / polydopamine / talc nanocomposite material. Then, oleic acid is grafted onto the obtained borate / polydopamine / talc nanocomposite material to prepare an oleic acid-modified borate / polydopamine / talc nanocomposite material. The general structural formula of the oleic acid-modified borate / polydopamine / talc nanocomposite material is as follows:

[0010]

[0011] Furthermore, the water contact angle of the oleic acid-modified borate / polydopamine / talc nanocomposite is 143–145°.

[0012] A method for preparing the oleic acid-modified borate / polydopamine / talc nanocomposite material as described above includes the following steps:

[0013] (1) Preparation of borate / polydopamine / talc nanocomposite material: Talc powder was dispersed in water, then dopamine hydrochloride, H2O2 and acetate dihydrate were added and ultrasonically mixed to obtain solution A. Sodium borate decahydrate was dissolved in water to obtain solution B. Solution A and solution B were then mixed to obtain solution B. The resulting mixed solution was transferred to a high-pressure reactor for hydrothermal reaction. After the reaction was completed, the solution was naturally cooled to room temperature. After filtration, washing, precipitation and vacuum freeze drying, borate / polydopamine / talc nanocomposite material was obtained.

[0014] (2) Preparation of oleic acid modified borate / polydopamine / talc nanocomposite material: The borate / polydopamine / talc nanocomposite material and oleic acid aqueous emulsion were added to a mechanical activation reactor for mechanical activation, and then the resulting product was freeze-dried under vacuum to obtain oleic acid modified borate / polydopamine / talc nanocomposite material.

[0015] Further, in step (1), the acetate dihydrate is zinc acetate dihydrate, copper acetate dihydrate, nickel acetate dihydrate, or cobalt acetate dihydrate.

[0016] Further, in step (1), the mass ratio of talc, dopamine hydrochloride and acetate dihydrate in solution A is 0.38:0.08-0.1:0.1-0.15, the mass-to-volume ratio of talc to H2O2 is 0.38g:0.2-0.3mL, and the mass-to-volume ratio of talc to water is 0.38g:65-70mL.

[0017] Further, in step (1), the mass ratio of sodium borate decahydrate to water in solution B is 0.19 g: 40-45 mL; the mass ratio of sodium borate decahydrate to talc is 0.18-0.2: 0.38.

[0018] Further, in step (1), the temperature of the hydrothermal reaction is 200-250℃ and the time is 3.5-4h; the temperature of the vacuum freeze drying is -40 to -30℃ and the time is 10-12h.

[0019] Further, in step (2), the mass-to-volume ratio of the borate / polydopamine / talc nanocomposite material and the oleic acid emulsion is 0.6g:50-60mL; and the volume concentration of the oleic acid emulsion is 25-30μL / mL.

[0020] Further, in step (2), the mechanical activation is as follows: adding ball milling media with a mass ratio of 0.6:30 to 40 with the borate / polydopamine / talc nanocomposite material, and ball milling for 3.5 to 4 hours at a speed of 500 to 600 rpm; the ball milling media is zirconium balls; the vacuum freeze-drying temperature is -40 to -30°C, and the time is 10 to 12 hours.

[0021] The application of an oleic acid-modified borate / polydopamine / talc nanocomposite as described above as a lubricating oil additive; applying the lubricating oil additive to base oils such as rapeseed oil and polyalphaolefin (PAO) can effectively reduce the tribological properties of the base oil.

[0022] The following describes the preparation principle of the oleic acid-modified borate / polydopamine / talc nanocomposite material of the present invention, taking the preparation of oleic acid-modified zinc borate / polydopamine / talc nanocomposite material (denoted as OA-ZB / PDA / PU) as an example:

[0023] In this invention, dopamine hydrochloride (DA) and Zn 2+ The DA (dopaquinone) and talc (denoted as PU) are uniformly mixed under ultrasonication. DA is oxidized to dopaquinone by hydrogen peroxide. After adding sodium borate solution, Zn... 2+ With B4O7 2- The zinc borate precipitate (denoted as ZB) is rapidly formed by the rapid combination. The solution is then transferred to a high-temperature reactor, where, driven by high-temperature thermodynamics, the combined ZB redissolves into Zn. 2+ and B4O7 2- Then Zn 2+ B4O7 2- It enters the PU interlayer along with dopaquinone molecules. Finally, dopaquinone combines with Zn. 2+ A chelation reaction occurs, providing spatial confinement and numerous binding sites for the dense and strong binding of zinc ions. The "binding" and "bridging" effects are achieved through hydrogen bonding between dopamine-rich functional groups and PU. During the hydrothermal process, DA accelerates self-polymerization to form polydopamine (PDA), further stabilizing the "binding" and "bridging" effects. Under the anchoring effect of PDA, ZB can grow uniformly on the surface of PU and between its layers. Finally, the obtained ZB / PDA / PU is mixed with an oleic acid aqueous emulsion (OA) and added to a ball mill jar for mechanical ball milling. Under mechanical force, the long-chain alkyl groups of OA bond with the active functional groups of PDA. Simultaneously, this step can mechanically exfoliate the layered structure of ZB / PDA / PU, ultimately yielding OA-ZB / PDA / PU.

[0024] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0025] 1. This invention uses polydopamine as a bridging agent to stably bond borate nanoparticles to the surface and interlayer of talc flakes, effectively reducing the stacking of talc flakes and overcoming the shortcomings of traditional inorganic nanomaterials that easily accumulate and settle in lubricating oil. The polydopamine structure contains benzene rings and amino groups, providing binding sites for the introduction of long-chain alkyl structures from oleic acid. The introduction of oleic acid further improves the dispersion stability of inorganic nanoparticles in lubricating oil. Furthermore, the nitrogen atom contains lone pairs of electrons, exhibiting certain reducing properties, thereby improving the antioxidant properties of the lubricating oil.

[0026] 2. This invention prepares oleic acid-modified borate / polydopamine / talc nanocomposite materials using an intercalation method. With the help of oleic acid, borate nanoparticles can better electrostatically adsorb onto the friction pair surface during friction, thus more easily forming a thin protective film and reducing friction damage. Simultaneously, the addition of talc, whose surface contains numerous unsaturated or dangling bonds such as Si-O-Si, O-Si-O, Mg-O / -OH, and hydrogen bonds, exhibits strong physicochemical activity and polarity. During friction, it has a high affinity for the friction pair surface, rapidly forming a tribochemical reaction film with unique tribological properties. Furthermore, it can effectively fill surface scratches and reduce mechanical damage; the synergistic effect of both materials achieves a friction-reducing and anti-wear effect.

[0027] 3. The composite material of this invention, when used as a lubricating oil additive in various base oils, exhibits significant lubrication effects with small addition amounts and demonstrates excellent dispersion stability in base oils. When applied to rapeseed oil and polyalphaolefin (PAO), the average wear scar diameters are 0.35 mm and 0.36 mm, respectively, and the average friction coefficients are 0.063 and 0.067, effectively improving the tribological properties of the base oils. The preparation method of this invention uses safe, environmentally friendly, and pollution-free raw materials, has a simple preparation process, and low production costs. The resulting composite material has broad economic and social benefits and is worthy of large-scale promotion and application. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the preparation process of OA-ZB / PDA / PU in Example 1.

[0029] Figure 2 The images show the XRD patterns of OA-ZB / PDA / PU, ZB, ZB / PU, ZB / PDA / PU, and PU prepared in Example 1 and Comparative Examples 1-3, respectively.

[0030] Figure 3 The FT-IR images are of OA-ZB / PDA / PU, ZB, ZB / PU, ZB / PDA / PU, PU, ​​and OA, respectively, prepared in Example 1 and Comparative Examples 1-3.

[0031] Figure 4 XPS images of OA-ZB / PDA / PU, ZB / PU, and ZB / PDA / PU prepared in Example 1 and Comparative Examples 2-3, respectively.

[0032] Figure 5 The images show SEM images of OA-ZB / PDA / PU, ZB, ZB / PU, ZB / PDA / PU, and PU prepared in Example 1 and Comparative Examples 1-3, respectively.

[0033] Figure 6 The WCA diagrams are for OA-ZB / PDA / PU, ZB, ZB / PU, ZB / PDA / PU and PU obtained in Example 1 and Comparative Examples 1-3, respectively.

[0034] Figure 7 The AFM images are of ZB / PDA / PU and OA-ZB / PDA / PU prepared in Comparative Example 3 and Example 1, respectively.

[0035] Figure 8 The images show TEM images of ZB / PDA / PU and OA-ZB / PDA / PU prepared in Comparative Example 3 and Example 1, respectively.

[0036] Figure 9 The graph shows the dispersion and dispersion stability test results of ZB / PU, ZB / PDA / PU, and OA-ZB / PDA / PU prepared in Comparative Examples 2-3 and Example 1, respectively, in rapeseed oil. Detailed Implementation

[0037] The present invention will be further described in detail below through embodiments. These embodiments are only used to illustrate the present invention and do not limit the scope of protection of the present invention.

[0038] Example 1

[0039] Preparation of oleic acid-modified zinc borate / polydopamine / talc nanocomposites:

[0040] 0.38 g of talc powder was dispersed in 70 mL of deionized water, and then 0.09 g of dopamine hydrochloride, 0.2 mL of H₂O₂, and 0.11 g of zinc acetate dihydrate were added. The mixture was sonicated for 1 h. Simultaneously, 0.19 g of sodium borate decahydrate was dissolved in 40 mL of deionized water. The two liquids were mixed thoroughly and transferred to a 200 mL Teflon-lined stainless steel autoclave for hydrothermal reaction at 200 °C for 4 h. After the reaction, the mixture was allowed to cool naturally to room temperature. The precipitate was washed with deionized water, and the resulting sample was freeze-dried under vacuum at -30 °C for 12 h to obtain the zinc borate / polydopamine / talc nanocomposite material (denoted as ZB / PDA / PU). 0.6 g of ZB / PDA / PU sample, 50 mL of oleic acid aqueous emulsion (30 μL / mL), and 30 g of zirconium balls (d = 1 mm) were added to a ball mill jar and ball-milled at 500 rpm for 4 h. After ball milling, the zirconium balls and water were filtered off, and the resulting sample was freeze-dried under vacuum at -30 °C for 12 h to obtain an oleic acid-modified zinc borate / polydopamine / talc nanocomposite material (denoted as OA-ZB / PDA / PU). A schematic diagram of its preparation process is shown below. Figure 1 As shown.

[0041] Example 2

[0042] Preparation of oleic acid-modified copper borate / polydopamine / talc nanocomposites:

[0043] 0.38 g of talc powder was dispersed in 70 mL of deionized water, and then 0.1 g of dopamine hydrochloride, 0.3 mL of H₂O₂, and 0.15 g of copper acetate dihydrate were added. The mixture was sonicated for 1 h. Simultaneously, 0.2 g of sodium borate decahydrate was dissolved in 45 mL of deionized water. The two liquids were mixed thoroughly and transferred to a 200 mL Teflon-lined stainless steel autoclave for hydrothermal reaction at 250 °C for 3.5 h. After the reaction, the mixture was allowed to cool naturally to room temperature. The precipitate was filtered and washed with deionized water. The resulting sample was then freeze-dried under vacuum at -40 °C for 10 h to obtain the copper borate / polydopamine / talc nanocomposite material (denoted as CuB / PDA / PU). 0.6 g of CuB / PDA / PU sample, 60 mL of oleic acid aqueous emulsion (25 μL / mL) and 40 g of zirconium balls (d = 1 mm) were added to a ball mill jar and ball-milled at 600 rpm for 3.5 h. After ball milling, the zirconium balls and water were filtered off, and the obtained sample was freeze-dried under vacuum at -40 °C for 10 h to obtain oleic acid modified copper borate / polydopamine / talc nanocomposite material (denoted as OA-CuB / PDA / PU).

[0044] Example 3

[0045] Preparation of oleic acid-modified nickel borate / polydopamine / talc nanocomposites:

[0046] 0.38 g of talc powder was dispersed in 70 mL of deionized water, and then 0.09 g of dopamine hydrochloride, 0.3 mL of H₂O₂, and 0.13 g of nickel acetate dihydrate were added. The mixture was sonicated for 1 h. Simultaneously, 0.19 g of sodium borate decahydrate was dissolved in 42 mL of deionized water. The two liquids were mixed thoroughly and transferred to a 200 mL Teflon-lined stainless steel autoclave for hydrothermal reaction at 220 °C for 4 h. After the reaction, the mixture was allowed to cool naturally to room temperature. The precipitate was filtered and washed with deionized water, and the resulting sample was freeze-dried under vacuum at -30 °C for 11 h to obtain the nickel borate / polydopamine / talc nanocomposite material (denoted as NiB / PDA / PU). 0.6 g of NiB / PDA / PU sample, 55 mL of oleic acid aqueous emulsion (30 μL / mL) and 30 g of zirconium balls (d = 1 mm) were added to a ball mill jar and ball-milled at 550 rpm for 4 h. After ball milling, the zirconium balls and water were filtered off, and the obtained sample was freeze-dried under vacuum at -30 °C for 11 h to obtain oleic acid modified nickel borate / polydopamine / talc nanocomposite material (denoted as OA-NiB / PDA / PU).

[0047] Example 4

[0048] Preparation of oleic acid-modified cobalt borate / polydopamine / talc nanocomposites:

[0049] 0.38 g of talc powder was dispersed in 70 mL of deionized water, and then 0.08 g of dopamine hydrochloride, 0.2 mL of H₂O₂, and 0.1 g of cobalt acetate dihydrate were added. The mixture was sonicated for 1 h. Simultaneously, 0.18 g of sodium borate decahydrate was dissolved in 40 mL of deionized water. The two liquids were mixed thoroughly and transferred to a 200 mL Teflon-lined stainless steel autoclave for hydrothermal reaction at 200 °C for 4 h. After the reaction, the mixture was allowed to cool naturally to room temperature. The precipitate was washed with deionized water, and the resulting sample was freeze-dried under vacuum at -35 °C for 12 h to obtain the cobalt borate / polydopamine / talc nanocomposite material (denoted as CoB / PDA / PU). 0.6 g of CoB / PDA / PU sample, 50 mL of oleic acid aqueous emulsion (27 μL / mL) and 30 g of zirconium balls (d = 1 mm) were added to a ball mill jar and ball-milled at 500 rpm for 4 h. After ball milling, the zirconium balls and water were filtered off, and the obtained sample was freeze-dried under vacuum at -35 °C for 12 h to obtain oleic acid modified cobalt borate / polydopamine / talc nanocomposite material (denoted as OA-CoB / PDA / PU).

[0050] Comparative Example 1

[0051] Preparation of zinc borate:

[0052] 0.11 g of zinc acetate dihydrate was dispersed in 70 mL of deionized water and sonicated for 1 h. Simultaneously, 0.19 g of sodium borate decahydrate was dissolved in 40 mL of deionized water. The two liquids were mixed thoroughly and transferred to a 200 mL Teflon-lined stainless steel autoclave for hydrothermal reaction at 200 °C for 4 h. After the reaction, the mixture was allowed to cool naturally to room temperature. The precipitate was filtered and washed with deionized water, and the resulting sample was freeze-dried under vacuum for 12 h to obtain zinc borate (denoted as ZB).

[0053] Comparative Example 2

[0054] Preparation of zinc borate / talc composite materials:

[0055] 0.38 g of talc powder was dispersed in 70 mL of deionized water, and then 0.11 g of zinc acetate dihydrate was added and sonicated for 1 h. Simultaneously, 0.19 g of sodium borate decahydrate was dissolved in 40 mL of deionized water. The two liquids were mixed thoroughly and transferred to a 200 mL Teflon-lined stainless steel autoclave for hydrothermal reaction at 200 °C for 4 h. After the reaction, the mixture was allowed to cool naturally to room temperature, and the precipitate was washed with deionized water. The resulting sample was then freeze-dried under vacuum for 12 h to obtain the zinc borate / talc composite material (denoted as ZB / PU).

[0056] Comparative Example 3

[0057] Preparation of zinc borate / polydopamine / talc nanocomposites:

[0058] 0.38 g of talc powder was dispersed in 70 mL of deionized water, and then 0.09 g of dopamine hydrochloride, 0.2 mL of H₂O₂, and 0.11 g of zinc acetate dihydrate were added. The mixture was sonicated for 1 h. Simultaneously, 0.19 g of sodium borate decahydrate was dissolved in 40 mL of deionized water. The two liquids were mixed thoroughly and transferred to a 200 mL Teflon-lined stainless steel autoclave for hydrothermal reaction at 200 °C for 4 h. After the reaction, the mixture was allowed to cool naturally to room temperature. The precipitate was filtered and washed with deionized water, and the resulting sample was freeze-dried under vacuum for 12 h to obtain the zinc borate / polydopamine / talc nanocomposite material (denoted as ZB / PDA / PU).

[0059] Material characterization analysis

[0060] (I) X-ray diffraction (XRD) analysis

[0061] X-ray diffraction (XRD) was used to characterize OA-ZB / PDA / PU, ZB, ZB / PU, ZB / PDA / PU, and PU prepared in Example 1 and Comparative Examples 1-3, respectively, to explore the phase information of the materials. The characterization results are as follows: Figure 2 As shown. Figure 2In Chinese, "PU" stands for talc.

[0062] Depend on Figure 2 It can be seen that the XRD pattern of ZB corresponds well to the typical structure of ZnB4O7 (PDF#24-1438), and its characteristic peaks at 2θ = 21.9°, 26°, 28.4°, 31.2°, 33.7°, 36.1° and 40.5° correspond to the (020), (400), (302), (321) and (113), (511), (512) lattice planes, respectively; the XRD pattern of PU corresponds well to Mg3Si4O 10 The monoclinic crystal structure of (OH)₂ (PDF#13-0558) has characteristic peaks at 2θ = 9.5°, 19°, and 28.6°, corresponding to the (002), (004), and (006) lattice planes. Compared with the ZB / PU spectrum, the peak intensities of ZB / PDA / PU at 2θ = 31.2° and 33.7° are weakened, which may be related to the introduction of PDA. Compared with the XRD pattern of ZB / PDA / PU, OA-ZB / PDA / PU shows almost no ZB characteristic peaks at 2θ = 31.2° and 33.7°, and the peak intensities at 2θ = 9.5°, 19°, and 28.6° become broad and weak. This may be related to the further regulation of ZB growth by OA during mechanical activation treatment. The introduction of long-chain alkyl groups enhances the steric hindrance effect, while mechanical force effectively exfoliates the layered PU.

[0063] (II) Fourier Transform Infrared Spectroscopy (FT-IR) Analysis

[0064] Fourier transform infrared spectroscopy (FT-IR) was used to characterize and analyze OA-ZB / PDA / PU, ZB, ZB / PU, ZB / PDA / PU, PU, ​​and OA prepared in Example 1 and Comparative Examples 1-3, respectively, to determine the functional groups of the materials. The characterization results are as follows: Figure 3 As shown. Figure 3 In this context, "OA" represents oleic acid.

[0065] Depend on Figure 3 It can be seen that the FT-IR spectrum of OA-ZB / PDA / PU is at 1020 cm⁻¹. -1 and 725cm -1 The absorption peaks at these locations correspond to -B (3) -O and -B (4) -O tensile vibration, which coincides with the characteristic peak of ZB; 3680cm -1 675cm -1 and 469cm -1 The absorption peaks at 2930 cm⁻¹ correspond to the stretching vibrations of hydroxyl groups, Mg-O bonds, and Si-O bonds, respectively, which are consistent with the peak values ​​of PU;-1 and 2850cm -1 The characteristic absorption peaks at 1020 cm⁻¹ correspond to the stretching vibration modes of -CH₃ and -CH₂, respectively; -1 The enhanced absorption peak at 1440 cm⁻¹ may be related to the phenolic carbon-oxygen stretching vibration of PDA; -1 The absorption peak at the point may originate from the -C=C stretching vibration of OA grafted onto the PU surface. The appearance of characteristic peaks for OA, ZB, PDA, and PU indicates the successful synthesis of the composite, consistent with the XRD analysis results.

[0066] (III) X-ray photoelectron spectroscopy (XPS) analysis

[0067] The surface chemical states of OA-ZB / PDA / PU, ZB / PU, and ZB / PDA / PU prepared in Example 1 and Comparative Examples 2-3 were analyzed using X-ray photoelectron spectroscopy (XPS). The analytical results are as follows: Figure 4 As shown. High-resolution C, B, O, Zn, Si, Mg, and N XPS spectra provide detailed information on surface chemistry using Thermo Avantage fitting software.

[0068] Depend on Figure 4 (a) shows that the C1s XPS spectra of ZB / PDA / PU and OA-ZB / PDA / PU exhibit three peaks corresponding to the chemical bands CC / C=C (284.8 eV), CO (286 eV), and CC=O (288.5 eV). Compared with ZB / PDA / PU, the CC / C=C peak of OA-ZB / PDA / PU is significantly enhanced, which may be due to the long-chain alkyl groups of oleic acid bonding with ZB / PDA / PU through hydrogen bonds during ball milling, consistent with the results shown in the FT-IR spectra. Figure 4 (b) It can be seen that the N1s spectra of ZB / PDA / PU and OA-ZB / PDA / PU show peaks corresponding to the chemical band of C-NH2 (399.3 eV). Figure 4 (c) shows that the B1s spectra of ZB / PU, ZB / PDA / PU, and OA-ZB / PDA / PU exhibit a BO peak. Figure 4 (d) It can be seen that the O1s spectra of ZB / PU, ZB / PDA / PU, and OA-ZB / PDA / PU show four peaks corresponding to the chemical bands of Mg-O (530 eV), CO (531.4 eV), BO (532.2 eV), and Si-O (533 eV). This may be because the introduction of PDA and the mechanical exfoliation process did not disrupt the composition of the composite material. Figure 4 (e) shows that the Zn 2p spectra of ZB / PU, ZB / PDA / PU, and OA-ZB / PDA / PU exhibit Zn 2p...3 / 2 (1022.3 eV) and Zn 2p 1 / 2 The two peaks corresponding to the chemical band at (1045.4 eV). (By...) Figure 4 (f) shows that the Si 2p spectra of ZB / PU, ZB / PDA / PU, and OA-ZB / PDA / PU exhibit peaks corresponding to the chemical band of Si-O (102.7 eV). Figure 4 (g) As shown, the Mg 1s spectra of ZB / PU, ZB / PDA / PU, and OA-ZB / PDA / PU exhibit Mg-O (1304.6 eV), Mg-O (1304.8 eV), and Mg-O (1304 eV), respectively. These analyses indicate that OA-ZB / PDA / PU was successfully synthesized using a hydrothermal synergistic mechanical exfoliation method, establishing a robust chemical bridge between ZB and PU and enhancing their synergistic effect in the friction and lubrication process.

[0069] (iv) Scanning Electron Microscopy (SEM) Analysis

[0070] Scanning electron microscopy (SEM) was used to characterize and analyze the OA-ZB / PDA / PU, ZB, ZB / PU, ZB / PDA / PU, and PU prepared in Example 1 and Comparative Examples 1-3, respectively. The characterization results are as follows: Figure 5 As shown.

[0071] Depend on Figure 5 (a) As can be seen, PU has a layered stacked structure. During friction, layered materials primarily rely on interlayer slippage to counteract frictional forces and achieve lubrication. However, layered PU is prone to breakage during friction, thus requiring modification to enhance its lubrication performance. Figure 5 (b) It can be seen that ZB consists of nanoparticles with non-uniform shapes and aggregated together. This may be because zinc borate is an ionic mineral; when anions and cations come into contact, it precipitates rapidly and easily forms large crystals with poor dispersibility, poor particle size distribution, and poor particle size distribution. Figure 5 (c) It can be seen that in the ZB / PU material, nano-zinc borate (denoted as ZB NPs) is randomly deposited on the surface of talc powder, and... Figure 5 (b) Compared to zinc borate, the agglomeration of zinc borate was somewhat improved, but its tribological properties still did not achieve satisfactory results. Figure 5 (d) shows that, compared to ZB / PU, the ZB NPs anchored on the ZB / PDA / PU surface are more dispersed and have a higher density. This result indicates that PDA / PU can provide spatial constraint and binding network, and PDA enhances the dispersion and adhesion of ZB NPs, thereby preventing uncontrolled growth of ZB NPs. This strategy solves the problem of easy aggregation and sedimentation of ZB nanoparticles in base oils.

[0072] (V) Water Contact Angle (WCA) Analysis

[0073] The water contact angle (WCA) was used to characterize and analyze the OA-ZB / PDA / PU, ZB, ZB / PU, ZB / PDA / PU, and PU prepared in Example 1 and Comparative Examples 1-3, respectively. The test results are as follows: Figure 6 As shown.

[0074] Depend on Figure 6 (a) It can be seen that the water contact angle of PU is 136°. This may be because talc has a structure similar to nonpolar siloxanes, and the symmetrical and dense Si-O and O-Si-O bonds give it low surface energy and thus hydrophobicity. Figure 6 (b) It can be seen that the high surface energy nano-ZB exhibits hydrophilicity, with a water contact angle of 0°. From Figure 6 (c) It can be seen that the water contact angle of ZB / PU is 0°, which can be attributed to the hydrophilic ZB coating on the PU surface. Figure 6 (d) shows that the water contact angle of ZB / PDA / PU is 0°. The hydrophilic ZB / PDA / PU is difficult to disperse stably in lubricating oil, therefore hydrophobic modification is necessary. Figure 6 (e) shows that the contact angle of OA-ZB / PDA / PU is 143°. This is because the grafting of long-chain OA with ZB / PDA / PU significantly reduces its surface energy, making it hydrophobic. The hydrophilic end of the superdispersant molecule is tightly bound to PDA through hydrogen bonds and van der Waals forces, while the hydrophobic end is a polymer chain of a certain length that can dissolve in the dispersion medium; this is called a solvated chain. When the particles adsorbed by the superdispersant approach each other, the spatial barrier of the solvent chain acts as a "spacer" and "scaffold," enabling stable diffusion of the particles in the medium. Therefore, it is beneficial for improving the dispersibility and dispersion stability of OA-ZB / PDA / PU in base oils, as well as its tribological properties.

[0075] (vi) Atomic Force Microscopy (AFM) Analysis

[0076] Atomic force microscopy (AFM) was used to characterize and analyze the ZB / PDA / PU and OA-ZB / PDA / PU prepared in Comparative Example 3 and Example 1, respectively, to detect the degree of material peeling. The characterization results are as follows: Figure 7 As shown.

[0077] Depend on Figure 7 (a) It can be seen that the thickness of the ZB / PDA / PU nanosheets is 300–500 nm, while... Figure 7 (b) It can be seen that the length of the OA-ZB / PDA / PU nanosheets is 50–120 nm. This indicates that under mechanical force, the thickness of ZB / PDA / PU decreases, achieving the purpose of exfoliation.

[0078] (vii) Transmission Electron Microscopy (TEM) Analysis

[0079] Transmission electron microscopy (TEM) was used to characterize and analyze the ZB / PDA / PU and OA-ZB / PDA / PU prepared in Comparative Example 3 and Example 1, respectively. The characterization results are as follows: Figure 8 As shown.

[0080] Depend on Figure 8 (a) It can be seen that the TEM image of ZB / PDA / PU shows a multi-layer stacked structure, while Figure 8 In (b), the multilayered stacked structure is barely visible in the TEM image of OA-ZB / PDA / PU. This result confirms that ZB / PDA / PU was stripped after the ball milling process, consistent with the AFM results. Figure 8 In (c), the (006) crystal surface of ZnB4O7 and Mg3[Si4O 10 The lattice stripes appearing on the (006) crystal surface also confirm the successful growth of ZB NPs on the PU surface.

[0081] (viii) Dispersion and Dispersion Stability Analysis

[0082] The free time of ZB / PU, ZB / PDA / PU, and OA-ZB / PDA / PU prepared in Comparative Examples 2-3 and Example 1 in rapeseed oil was tested and analyzed to further study the dispersion and dispersion stability of the materials in rapeseed oil. Each material was added to an equal volume of rapeseed oil at a concentration of 0.2 wt% at 25°C. After ultrasonic treatment, the mixtures were left to stand for 0 h, 12 h, 3 d, and 7 d. The test results are as follows: Figure 9 As shown. Figure 9 In the figure, ① represents ZB / PU, ② represents ZB / PDA / PU, and ③ represents OA-ZB / PDA / PU. Figures (a), (b), (c), and (d) represent the results of rapeseed oil after being stored for 0 h, 12 h, 3 d, and 7 d, respectively.

[0083] Depend on Figure 9 (a) It can be seen that after ultrasonic treatment, ZB / PU, ZB / PDA / PU, and OA-ZB / PDA / PU can initially be uniformly dispersed in rapeseed oil. From Figure 9 (b) It can be seen that ZB / PU exhibits significant deposition after standing for 12 hours. This may be because the ZB NPs dispersed on the PU surface tend to aggregate, making it difficult to form a stable and uniform dispersion system in the oil. In contrast, in Figure 9In (c), ZB / PDA / PU only showed stratification after standing in rapeseed oil for 3 days, and no hard sedimentation occurred even after 7 days of storage. This phenomenon is attributed to the thermodynamically driven rapid self-polymerization of PDA on the PU surface and between the layers. The intertwined polydopamine fixed on the two-dimensional talc surface forms a network structure, providing uniform chelation sites and effectively controlling the uniformity of ZB growth on the PU surface and between layers. Furthermore, in… Figure 9 In (d), after soaking in rapeseed oil for 7 days, OA-ZB / PDA / PU showed no significant stratification or sedimentation compared to ZB / PDA / PU, demonstrating the superiority of the oleic acid superdispersant. The hydrophilic end of the superdispersant molecule is tightly bound to PDA through hydrogen bonds and van der Waals forces, while the hydrophobic end is a polymer chain of a certain length that can dissolve in the dispersion medium, known as a solvated chain. When the particles adsorbed by the superdispersant approach each other, the spatial barrier of the solvent chain acts as a "spacer" and "scaffold," achieving stable diffusion of the particles in rapeseed oil.

[0084] Application Example 1

[0085] The oleic acid-modified zinc borate / polydopamine / talc nanocomposite material prepared in Example 1 was added to rapeseed oil at a concentration of 0.2 wt%. Its tribological properties were investigated using a four-ball friction tester. The conditions for the four-ball friction test were: test load 392 N, running speed 1200 r / m, and running time 60 min. The average wear scar diameter was 0.35 mm and the average friction coefficient was 0.063. The extreme pressure test was conducted according to the test method of GB / T 3142-82. The test conditions were: time 10 s and speed 1450 rpm. The average extreme pressure value was 922 N.

[0086] The same test was conducted by replacing rapeseed oil with PAO using the same method. The average wear scar diameter was 0.36 mm, the average coefficient of friction was 0.067, and the average extreme pressure was 549 N.

[0087] Application Comparative Example 1

[0088] Talc powder was added to rapeseed oil at a concentration of 0.2 wt%, and its tribological properties were investigated using a four-ball friction tester. The conditions for the four-ball friction test were: test load 392 N, running speed 1200 r / m, and running time 60 min. The average wear scar diameter obtained from the experiment was 0.72 mm, and the average friction coefficient was 0.081. The extreme pressure test method was carried out according to GB / T 3142-82 test method, and the test conditions were: time 10 s, speed 1450 rpm. The average extreme pressure value obtained from the experiment was 726 N.

[0089] The same test was conducted by replacing rapeseed oil with PAO using the same method. The average wear scar diameter was 0.63 mm, the average coefficient of friction was 0.084, and the average extreme pressure was 412 N.

[0090] Application Comparative Example 2

[0091] The zinc borate prepared in Comparative Example 1 was added to rapeseed oil at a concentration of 0.2 wt%. Its tribological properties were investigated using a four-ball friction tester. The conditions for the four-ball friction test were: test load 392 N, running speed 1200 r / m, and running time 60 min. The average wear scar diameter was 0.73 mm and the average friction coefficient was 0.077. The extreme pressure test was conducted according to the test method of GB / T3142-82. The test conditions were: time 10 s and speed 1450 rpm. The average extreme pressure value was 746 N.

[0092] The same test was conducted by replacing rapeseed oil with PAO using the same method. The average wear scar diameter was 0.67 mm, the average coefficient of friction was 0.088, and the average extreme pressure was 431 N.

[0093] Application Comparative Example 3

[0094] The zinc borate / talc composite material prepared in Comparative Example 2 was added to rapeseed oil at a concentration of 0.2 wt%. Its tribological properties were investigated using a four-ball friction tester. The conditions for the four-ball friction test were: test load 392 N, running speed 1200 r / m, and running time 60 min. The average wear scar diameter was 0.75 mm and the average friction coefficient was 0.082. The extreme pressure test was conducted according to GB / T 3142-82. The test conditions were: time 10 s and speed 1450 rpm. The average extreme pressure value was 785 N.

[0095] The same test was conducted by replacing rapeseed oil with PAO using the same method. The average wear scar diameter was 0.59 mm, the average coefficient of friction was 0.078, and the average extreme pressure was 471 N.

[0096] Application Comparative Example 4

[0097] The zinc borate / polydopamine / talc nanocomposite material prepared in Comparative Example 3 was added to rapeseed oil at a concentration of 0.2 wt%. Its tribological properties were investigated using a four-ball friction tester. The conditions for the four-ball friction test were: test load 392 N, running speed 1200 r / m, and running time 60 min. The average wear scar diameter was 0.58 mm and the average friction coefficient was 0.075. The extreme pressure test was conducted according to GB / T 3142-82 test method. The test conditions were: time 10 s and speed 1450 rpm. The average extreme pressure value was 863 N.

[0098] The same test was conducted by replacing rapeseed oil with PAO using the same method. The average wear scar diameter was 0.42 mm, the average friction coefficient was 0.073, and the average extreme pressure was 491 N.

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An oleic acid-modified borate / polydopamine / talc nanocomposite material, characterized in that, Using polydopamine as a bridging agent, borate nanoparticles are first bonded to the surface and interlayer of talc sheets via polydopamine to obtain a borate / polydopamine / talc nanocomposite material. Then, oleic acid is grafted onto the obtained borate / polydopamine / talc nanocomposite material to prepare an oleic acid-modified borate / polydopamine / talc nanocomposite material. The general structural formula of the oleic acid-modified borate / polydopamine / talc nanocomposite material is as follows: The method for preparing the oleic acid-modified borate / polydopamine / talc nanocomposite material includes the following steps: (1) Preparation of borate / polydopamine / talc nanocomposite material: Talc powder was dispersed in water, and then dopamine hydrochloride, H2O2 and acetate dihydrate were added and ultrasonically mixed to obtain solution A. Sodium borate decahydrate was dissolved in water to obtain solution B. Then solution A and solution B were mixed evenly and the resulting mixed solution was transferred to a high-pressure reactor for hydrothermal reaction. After the reaction was completed, it was naturally cooled to room temperature. After filtration, washing, precipitation and vacuum freeze drying, borate / polydopamine / talc nanocomposite material was obtained. (2) Preparation of oleic acid modified borate / polydopamine / talc nanocomposite material: The borate / polydopamine / talc nanocomposite material and oleic acid aqueous emulsion were added to a mechanical activation reactor for mechanical activation, and then the resulting product was vacuum freeze-dried to obtain oleic acid modified borate / polydopamine / talc nanocomposite material.

2. The oleic acid-modified borate / polydopamine / talc nanocomposite material according to claim 1, characterized in that, The water contact angle of the oleic acid-modified borate / polydopamine / talc nanocomposite is 143–145°.

3. A method for preparing an oleic acid-modified borate / polydopamine / talc nanocomposite material as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Preparation of borate / polydopamine / talc nanocomposite material: Talc powder was dispersed in water, and then dopamine hydrochloride, H2O2 and acetate dihydrate were added and ultrasonically mixed to obtain solution A. Sodium borate decahydrate was dissolved in water to obtain solution B. Then solution A and solution B were mixed evenly and the resulting mixed solution was transferred to a high-pressure reactor for hydrothermal reaction. After the reaction was completed, it was naturally cooled to room temperature. After filtration, washing, precipitation and vacuum freeze drying, borate / polydopamine / talc nanocomposite material was obtained. (2) Preparation of oleic acid modified borate / polydopamine / talc nanocomposite material: The borate / polydopamine / talc nanocomposite material and oleic acid aqueous emulsion were added to a mechanical activation reactor for mechanical activation, and then the resulting product was vacuum freeze-dried to obtain oleic acid modified borate / polydopamine / talc nanocomposite material.

4. The method for preparing the oleic acid-modified borate / polydopamine / talc nanocomposite material according to claim 3, characterized in that, In step (1), the acetate dihydrate is zinc acetate dihydrate, copper acetate dihydrate, nickel acetate dihydrate, or cobalt acetate dihydrate.

5. The method for preparing the oleic acid-modified borate / polydopamine / talc nanocomposite material according to claim 3, characterized in that, In step (1), the mass ratio of talc, dopamine hydrochloride and acetate dihydrate in solution A is 0.38:0.08-0.1:0.1-0.15, the mass-to-volume ratio of talc to H2O2 is 0.38 g: 0.2-0.3 mL, and the mass-to-volume ratio of talc to water is 0.38 g: 65-70 mL.

6. The method for preparing the oleic acid-modified borate / polydopamine / talc nanocomposite material according to claim 3, characterized in that, In step (1), the mass ratio of sodium borate decahydrate to water in solution B is 0.19 g : 40-45 mL; the mass ratio of sodium borate decahydrate to talc is 0.18-0.2 : 0.

38.

7. The method for preparing the oleic acid-modified borate / polydopamine / talc nanocomposite material according to claim 3, characterized in that, In step (1), the temperature of the hydrothermal reaction is 200-250℃ and the time is 3.5-4 h; the temperature of the vacuum freeze drying is -40 to -30℃ and the time is 10-12 h.

8. The method for preparing the oleic acid-modified borate / polydopamine / talc nanocomposite material according to claim 3, characterized in that, In step (2), the mass-to-volume ratio of the borate / polydopamine / talc nanocomposite material and the oleic acid emulsion is 0.6 g : 50-60 mL; the volume concentration of the oleic acid emulsion is 25-30 μL / mL.

9. The method for preparing the oleic acid-modified borate / polydopamine / talc nanocomposite material according to claim 3, characterized in that, In step (2), the mechanical activation is as follows: adding ball milling media with a mass ratio of 0.6:30 to 40 with the borate / polydopamine / talc nanocomposite material, and ball milling for 3.5 to 4 h at a speed of 500 to 600 rpm; the vacuum freeze drying temperature is -40 to -30℃ and the time is 10 to 12 h.

10. The application of an oleic acid-modified borate / polydopamine / talc nanocomposite material as described in claim 1 or 2 as a lubricating oil additive.

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