A kind of MOF-5 and its preparation and application, polymer self-lubricating composite material and its preparation and application

Abstract

The application belongs to the technical field of functional materials, and provides MOF-5, a preparation and application thereof, and a polymer self-lubricating composite material and a preparation and application thereof.A zinc salt, terephthalic acid, a capping agent (polyvinyl pyrrolidone or polyvinyl alcohol), a weak base (triethylamine or sodium acetate) and a solvent are mixed, and ultrasonic treatment is performed to obtain the MOF-5.The micro-morphology of the MOF-5 is in the form of a sheet layer, and the crystal face specificity is exposed by adding the capping agent and the weak base, so that the tribological performance can be improved when the MOF-5 is applied as a functional filler to a self-lubricating polymer.The MOF-5 mainly provides a reinforcing effect similar to that of crushed carbon fibers, and mainly acts as a bearing phase to bear the main load and contact the metal counterpart during the friction and wear process of the polymer self-lubricating composite material and the metal counterpart, and a uniform and continuous transfer film is formed on the surface of the metal counterpart, so that the tribological performance of the polymer self-lubricating composite material is improved.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, and in particular to a MOF-5 and its preparation and application, and a polymer self-lubricating composite material and its preparation and application. Background Technology

[0002] As a widely used novel material, MOFs are frequently applied in gas storage and transportation, organocatalysis, and drug delivery. Furthermore, organic ligands endow MOFs with abundant active groups on their surface. With their rich mesoporous structure, high thermal stability, excellent mechanical properties, and active surface groups, MOFs are often used as functional fillers in polymer composites. They can enhance the mechanical properties of composite materials and improve their flame retardant properties.

[0003] Meanwhile, as a classic MOF material, MOF-5 possesses excellent specific surface area, adsorption capacity, abundant active sites, and a stable framework structure, making it suitable as a functional filler. In existing technologies, MOF-5 has shown good results in dye wastewater treatment, carbon dioxide adsorption, and lithium-sulfur batteries; however, when used as a lubricating material, MOF-5 exhibits high tribological properties, particularly in volumetric wear. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide MOF-5 and its preparation and application, and polymer self-lubricating composite materials and their preparation and application. The MOF-5 provided by the present invention, when added as a functional material to a self-lubricating polymer, can reduce the volumetric wear of the resulting polymer self-lubricating composite material, thereby improving the tribological properties of the polymer self-lubricating composite material.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing MOF-5, comprising the following steps:

[0007] The zinc salt, terephthalic acid, capping agent, weak base and solvent are mixed and ultrasonically treated to obtain MOF-5;

[0008] The end-capping agent includes polyvinylpyrrolidone or polyvinyl alcohol;

[0009] The weak base includes triethylamine or sodium acetate.

[0010] Preferably, the zinc salt comprises zinc nitrate and / or zinc acetate, and the solvent comprises N-methylpyrrolidone.

[0011] Preferably, the mass ratio of the zinc salt to terephthalic acid is 5-20:2-6;

[0012] The mass ratio of terephthalic acid to the capping agent is 2-6:0-6, and the mass of the capping agent is not 0.

[0013] The mass ratio of terephthalic acid to weak base is 2-6:0-5, and the mass of weak base is not 0.

[0014] The mass ratio of the zinc salt to the solvent is 5–20:100.

[0015] Preferably, the ultrasonic treatment has a power of 500-800W and a duration of 20-60 minutes.

[0016] The present invention also provides MOF-5 prepared by the preparation method described in the above technical solution.

[0017] The present invention also provides the application of MOF-5 described in the above technical solution in polymer self-lubricating composite materials.

[0018] The present invention also provides a polymer self-lubricating composite material, comprising MOF-5 and polyetheretherketone, wherein the MOF-5 is the MOF-5 described in the above technical solution.

[0019] Preferably, the mass ratio of polyetheretherketone to MOF-5 is 33.6:0.3 to 3.5.

[0020] This invention also provides a method for preparing the polymer self-lubricating composite material described above, comprising the following steps:

[0021] Polyether ether ketone and MOF-5 were mixed and hot-pressed to obtain the polymer self-lubricating composite material.

[0022] The present invention also provides the application of the polymer self-lubricating composite material described in the above technical solution or the polymer self-lubricating composite material prepared by the preparation method described in the above technical solution in sliding bearings, gas compressors or automotive braking systems.

[0023] This invention provides a method for preparing MOF-5.

[0024] The preparation method provided by this invention, through the addition of a capping agent and a weak base, results in MOF-5 with a lamellar microstructure, a particle size of 1–5 μm, and specific exposure of crystal faces. When used as a functional filler in self-lubricating polymers, this reduces volumetric wear of the resulting self-lubricating composite material and improves its tribological properties. Furthermore, the ultrasonic treatment of this invention allows for a relatively large synthesis yield, making it suitable for industrial production.

[0025] This invention also provides a polymer self-lubricating composite material, which combines polyetheretherketone (PEEK) and MOF-5 as described in the above-mentioned technical solution. MOF-5 mainly provides a reinforcing effect similar to that of pulverized carbon fiber. During the friction and wear process between the polymer self-lubricating composite material and the metal pair, MOF-5 mainly acts as a load-bearing phase, bearing the main load and contacting the metal pair to form a uniform and continuous transfer film on the surface of the metal pair. This reduces the volumetric wear of the polymer self-lubricating composite material caused by the metal pair and improves the tribological properties of the polymer self-lubricating composite material. Attached Figure Description

[0026] Figure 1 Here is a scanning electron microscope image of the MOF-5 nanoparticles obtained in Example 1;

[0027] Figure 2 The XRD pattern of the MOF-5 nanoparticles obtained in Example 1 is shown below.

[0028] Figure 3 The curve showing the evolution of the friction coefficient of the polymer self-lubricating composite material obtained in Example 1 over time;

[0029] Figure 4 The image shows a scanning electron microscope (SEM) image of the worn surface obtained after testing the tribological properties of the polymer self-lubricating composite material obtained in Example 1.

[0030] Figure 5 The image shows a scanning electron microscope (SEM) image of the transfer film on the metal-pair surface after the tribological performance test of the polymer self-lubricating composite material obtained in Example 1. Detailed Implementation

[0031] This invention provides a method for preparing MOF-5, comprising the following steps:

[0032] The zinc salt, terephthalic acid, capping agent, weak base and solvent are mixed and ultrasonically treated to obtain MOF-5;

[0033] The end-capping agent includes polyvinylpyrrolidone or polyvinyl alcohol;

[0034] The weak base includes triethylamine or sodium acetate.

[0035] Unless otherwise specified, the raw materials used in this invention are preferably commercially available products.

[0036] In this invention, the zinc salt preferably comprises zinc nitrate and / or zinc acetate, more preferably zinc nitrate. Specifically, the zinc nitrate is preferably zinc nitrate hexahydrate. Specifically, the zinc acetate is preferably zinc acetate dihydrate.

[0037] In this invention, the terephthalic acid is used as an organic ligand.

[0038] In this invention, the capping agent includes polyvinylpyrrolidone (PVP) or polyvinyl alcohol (PVA), preferably polyvinylpyrrolidone.

[0039] In this invention, the weak base includes triethylamine (TEA) or sodium acetate (NaAc), preferably triethylamine.

[0040] In this invention, the solvent preferably includes N-methylpyrrolidone (NMP).

[0041] In this invention, the mass ratio of zinc salt to terephthalic acid is preferably 5-20:2-6, and more preferably 13.9:3.34 or 10.2:3.34.

[0042] In this invention, the mass ratio of terephthalic acid to the capping agent is preferably 2-6:0-6, and the mass of the capping agent is not 0, more preferably 2-6:0.1-6, and more specifically 3.34:3.36.

[0043] In this invention, the mass ratio of terephthalic acid to weak base is preferably 2-6:0-5, and the mass of weak base is not 0, more preferably 2-6:0.1-5, and more specifically 3.34:1.47.

[0044] In this invention, the mass ratio of the zinc salt to the solvent is preferably 5 to 20:100, and more preferably 13.9:100 or 10.2:100.

[0045] In this invention, the power of the ultrasonic treatment is preferably 500-800W, specifically 500W, 600W, 650W, 700W or 800W; the time is preferably 20-60min, specifically 20min, 30min, 40min, 50min or 60min.

[0046] After the ultrasonic treatment, the present invention preferably further includes solid-liquid separation of the obtained liquid, and the obtained solid is washed and dried sequentially to obtain MOF-5. In the present invention, the solid-liquid separation is preferably performed by centrifugation. In the present invention, the washing reagent is preferably ethanol, the washing method is preferably centrifugal washing, and the washing is preferably performed three times. In the present invention, the drying temperature is preferably 100–140°C, more preferably 120°C, and the drying time is preferably 8–16 hours, specifically 8 hours, 10 hours, 12 hours, or 16 hours.

[0047] This invention, by adding end-capping agents and weak bases, achieves a lamellar microstructure for MOF-5 with a particle size of 1–5 μm and specific exposed crystal faces. This allows it to be used as a functional filler in self-lubricating polymers, reducing volumetric wear and improving the tribological properties of the polymer self-lubricating composites. Furthermore, the ultrasonic treatment of this invention enables a relatively large synthesis volume, making it suitable for industrial production.

[0048] The present invention also provides MOF-5 prepared by the preparation method described in the above technical solution.

[0049] In this invention, MOF-5 is a metal-organic framework material with Zn ion clusters as the metal center and terephthalic acid as the organic ligand.

[0050] In this invention, the morphology of the MOF-5 is preferably lamellar. The particle size of the MOF-5 is preferably 1–5 μm.

[0051] The present invention also provides the application of MOF-5 described in the above technical solution in polymer self-lubricating composite materials.

[0052] The present invention also provides a polymer self-lubricating composite material, comprising MOF-5 and polyetheretherketone, wherein the MOF-5 is the MOF-5 described in the above technical solution.

[0053] In a specific embodiment of the present invention, the polyether ether ketone is preferably end-capped polyether ether ketone, and more preferably end-capped polyether ether ketone (FD-PEEK) 770PF-200 provided by Zhongyan Co., Ltd.

[0054] In this invention, the mass ratio of polyetheretherketone (PEEK) to MOF-5 is preferably 33.6:0.3 to 3.5, and more preferably 33.6:0.3, 33.6:0.7, 33.6:1.4, 33.6:2.8 or 33.6:3.5.

[0055] In this invention, MOF-5 in the polymer self-lubricating composite material mainly provides a reinforcing effect similar to that of pulverized carbon fiber. During the friction and wear process between the polymer self-lubricating composite material and the metal pair, MOF-5 mainly acts as a load-bearing phase, bearing the main load and contacting the metal pair to form a uniform and continuous transfer film on the surface of the metal pair. The formation of the transfer film can reduce the volume wear of the polymer self-lubricating composite material by the metal pair, thereby improving the tribological properties of the polymer self-lubricating composite material.

[0056] This invention also provides a method for preparing the polymer self-lubricating composite material described above, comprising the following steps:

[0057] Polyether ether ketone and MOF-5 were mixed and hot-pressed to obtain the polymer self-lubricating composite material.

[0058] In this invention, the polyetheretherketone (PEEK) is preferably used in the form of PEEK powder, and the particle size of the PEEK powder is preferably 200 mesh. In this invention, the particle size of the MOF-5 is preferably 1–5 μm.

[0059] Before use, the polyetheretherketone and MOF-5 are preferably pretreated, preferably by drying, and the drying temperature is preferably 120°C and the drying time is preferably 8 hours.

[0060] In this invention, the mixing of polyether ether ketone and MOF-5 is preferably carried out on a high-speed disperser.

[0061] In this invention, the temperature of the hot pressing is preferably 380-420°C, specifically 380°C, 390°C, 400°C, 410°C or 420°C; the pressure is preferably 3-6 MPa, specifically 3 MPa, 4 MPa, 5 MPa or 6 MPa; and the time is preferably 0.5-2 h, specifically 0.5 h, 1 h, 1.5 h or 2 h.

[0062] The present invention also provides the application of the polymer self-lubricating composite material described in the above technical solution or the polymer self-lubricating composite material prepared by the preparation method described in the above technical solution in sliding bearings, gas compressors or automotive braking systems.

[0063] In this invention, the polymer self-lubricating composite material is applied to a sliding bearing, and the polymer self-lubricating composite material is preferably made into a bearing cage.

[0064] In this invention, the polymer self-lubricating composite material is used in a gas compressor, and the polymer self-lubricating composite material is preferably made into a seal.

[0065] In this invention, the polymer self-lubricating composite material is used in automotive braking systems, and the polymer self-lubricating composite material is preferably made into brake pads.

[0066] The following examples illustrate in detail the MOF-5 provided by the present invention and its preparation and application, as well as the polymer self-lubricating composite material and its preparation and application. However, these examples should not be construed as limiting the scope of protection of the present invention.

[0067] The polyetheretherketone (PEEK) used in the following examples is end-capped polyetheretherketone (FD-PEEK) 770PF-200 provided by Zhongyan Co., Ltd.

[0068] Example 1

[0069] 1. Synthesis of MOF-5

[0070] 13.9 g of zinc nitrate hexahydrate, 3.34 g of terephthalic acid, 3.36 g of polyvinylpyrrolidone (PVP), and 1.47 g of triethylamine (TEA) were weighed into a 500 mL glass beaker using an analytical balance and dissolved in 100 g of N-methylpyrrolidone (NMP). An ultrasonic generator was then inserted and its power was adjusted to 650 W for ultrasonic treatment for 30 min. Finally, the liquid was centrifuged to collect the solid, which was washed three times with ethanol by centrifugation. The solid was then dried overnight in an oven at 120 °C to obtain MOF-5 nanoparticles with a particle size of 1–5 μm.

[0071] 2. Preparation of self-lubricating polymer composite materials

[0072] First, the PEEK (200 mesh) and MOF-5 nanoparticles were dried in an oven at 120℃ for 8 hours. Then, 33.6g of PEEK and 1.4g of MOF-5 nanoparticles were weighed using an electronic balance and mixed evenly using a high-speed disperser. Finally, hot pressing was performed at 400℃ for 1 hour under a controlled pressure of 4MPa to obtain a sheet-like polymer self-lubricating composite material. The sheet was then cut into 4×4×12mm sample pins for friction performance testing.

[0073] Example 2

[0074] 1. Synthesis of MOF-5

[0075] 13.9 g of zinc nitrate hexahydrate, 3.34 g of terephthalic acid, 3.36 g of polyvinylpyrrolidone (PVP), and 1.47 g of triethylamine (TEA) were weighed into a 500 mL glass beaker using an analytical balance and dissolved in 100 g of N-methylpyrrolidone (NMP). An ultrasonic generator was then inserted and its power was adjusted to 650 W for ultrasonic treatment for 30 min. Finally, the liquid was centrifuged to collect the solid, which was washed three times with ethanol by centrifugation. The solid was then dried overnight in an oven at 120 °C to obtain MOF-5 nanoparticles with a particle size of 1–5 μm.

[0076] 2. Preparation of self-lubricating polymer composite materials

[0077] First, the PEEK (200 mesh) and MOF-5 nanoparticles to be used were dried in an oven at 120℃ for 8 hours. Then, 33.6g of PEEK and 2.8g of MOF-5 were weighed using an electronic balance and mixed evenly using a high-speed disperser. Finally, hot pressing was performed at 400℃ for 1 hour under a controlled pressure of 4MPa to obtain a sheet-like polymer self-lubricating composite material. The sheet was then cut into 4×4×12mm sample pins for friction performance testing.

[0078] Example 3

[0079] 1. Synthesis of MOF-5

[0080] 13.9 g of zinc nitrate hexahydrate, 3.34 g of terephthalic acid, 3.36 g of polyvinylpyrrolidone (PVP), and 1.47 g of triethylamine (TEA) were weighed into a 500 mL glass beaker using an analytical balance and dissolved in 100 g of N-methylpyrrolidone (NMP). An ultrasonic generator was then inserted and set to 650 W for 30 min of ultrasonic treatment. Finally, the liquid was centrifuged to collect the solid, which was washed three times with ethanol by centrifugation. The solid was then dried overnight in an oven at 120 °C to obtain MOF-5 nanoparticles with a particle size of 1–5 μm.

[0081] 2. Preparation of self-lubricating polymer composite materials

[0082] First, the PEEK (200 mesh) and MOF-5 nanoparticles to be used were dried in an oven at 120℃ for 8 hours. Then, 33.6g of PEEK and 0.7g of MOF-5 were weighed using an electronic balance and mixed evenly using a high-speed disperser. Finally, hot pressing was performed at 400℃ for 1 hour under a controlled pressure of 4MPa to obtain a sheet-like polymer self-lubricating composite material. The sheet was then cut into 4×4×12mm sample pins for friction performance testing.

[0083] Example 4

[0084] 1. Synthesis of MOF-5

[0085] 10.2 g of zinc acetate dihydrate, 3.34 g of terephthalic acid, 3.36 g of polyvinyl alcohol (PVA), and 1.47 g of sodium acetate (NaAc) were weighed into a 500 mL glass beaker using an analytical balance and dissolved in 100 g of N-methylpyrrolidone (NMP). An ultrasonic generator was then inserted and set to 650 W for 30 min of ultrasonic treatment. Finally, the liquid was centrifuged to collect the solid, which was washed three times with ethanol by centrifugation. The solid was then dried overnight in an oven at 120 °C to obtain MOF-5 nanoparticles with a particle size of 1–5 μm.

[0086] 2. Preparation of self-lubricating polymer composite materials

[0087] First, the PEEK (200 mesh) and MOF-5 nanoparticles to be used were dried in an oven at 120℃ for 8 hours. Then, 33.6g of PEEK and 2.8g of MOF-5 were weighed using an electronic balance and mixed evenly using a high-speed disperser. Finally, a hot-pressing process was performed, with the applied pressure controlled at 4MPa and hot-pressed at 400℃ for 1 hour to obtain a sheet-like polymer self-lubricating composite material. The sheet was then cut into 4×4×12mm sample pins for friction performance testing.

[0088] Comparative Example 1

[0089] 1. Synthesis of MOF-5

[0090] 13.9 g of zinc nitrate hexahydrate and 3.34 g of terephthalic acid were weighed into a 500 mL glass beaker using an analytical balance and dissolved in 100 g of N-methylpyrrolidone (NMP). An ultrasonic generator was then inserted and set to 650 W for 30 min of ultrasonic treatment. Finally, the liquid was centrifuged to collect the solid, which was washed three times with ethanol and then dried overnight in an oven at 120 °C to obtain MOF-5 nanoparticles.

[0091] 2. Preparation of self-lubricating polymer composite materials

[0092] First, the PEEK (200 mesh) and MOF-5 powder materials to be used were dried in an oven at 120℃ for 8 hours. Then, 33.6g of PEEK and 1.4g of MOF-5 were weighed using an electronic balance and mixed evenly using a high-speed disperser. Finally, hot pressing was performed at 400℃ for 1 hour under a controlled pressure of 4MPa to obtain a sheet-like polymer self-lubricating composite material, denoted as PEEK / MOF-5 composite material. The sheet was then cut into 4×4×12mm sample pins for friction performance testing.

[0093] Comparative Example 2

[0094] 35g of PEEK (200 mesh) was weighed using an electronic balance and mixed evenly using a high-speed disperser. The mixture was then hot-pressed at 400℃ for 1 hour under a controlled pressure of 4MPa to obtain a sheet-like composite material. The sheet was then cut into 4×4×12mm sample pins for friction performance testing.

[0095] The composite materials obtained in Examples 1-4 and Comparative Examples 1-2 were subjected to friction performance tests. The parameters for the friction performance tests included: normal pressure of 4 MPa, linear velocity of 1 m / s, test duration of 2 h, and metal mating material of Cr15 rolling bearing steel. The volumetric wear rate was calculated using Ws = (m1-m2) / ρFL, where m1 is the mass of the sample pin before the friction test, m2 is the mass of the sample pin after the friction test, ρ is the density of the sample pin, F is the normal load, and L is the total test mileage. The results are shown in Table 1.

[0096] Table 1. Tribological performance results of the composite materials obtained in the examples and comparative examples.

[0097] steady-state friction coefficient <![CDATA[Volume wear rate (×10 -6 mm 3 / Nm)]]> Example 1 0.43 2.4 Example 2 0.45 4.6 Example 3 0.45 5.7 Example 4 0.48 5.5 Comparative Example 1 0.49 3.2 Comparative Example 2 0.38 7.8

[0098] As shown in Table 1, MOF-5, synthesized via end-capping agent and weak base induction, can serve as a tribologically enhancing filler, effectively improving the friction and wear resistance of polymer self-lubricating composites. The amount of MOF-5 added affects the tribological properties of the polymer self-lubricating composites. Among them, the polymer self-lubricating composite in Example 1 exhibits the best tribological properties.

[0099] Figure 1 The image shown is a scanning electron microscope (SEM) image of the MOF-5 nanoparticles obtained in Example 1. Figure 1 It can be seen that MOF-5 mainly has a plate-like structure with a particle size between 1 and 5 μm.

[0100] Figure 2 The image shows the XRD pattern of the MOF-5 nanoparticles obtained in Example 1. Figure 2 It can be seen that MOF-5 with specific crystal plane exposure was successfully synthesized.

[0101] Figure 3 The curve showing the evolution of the friction coefficient of the polymer self-lubricating composite material obtained in Example 1 over time is shown below. Figure 3 It can be seen that after a 1500s running-in period, the polymer self-lubricating composite material enters a steady state with a friction coefficient of 0.48.

[0102] Figure 4 The image shown is a scanning electron microscope (SEM) image of the worn surface obtained after testing the friction properties of the polymer self-lubricating composite material obtained in Example 1. Figure 4 Lamellar MOF-5 particles embedded in the matrix can be clearly observed, indicating that MOF-5 plays a load-bearing role during the friction and wear process of the composite material. Simultaneously, the MOF-5 lamellars exhibit peeling, which should be attributed to the exfoliating effect of interfacial shear forces on the MOF-5.

[0103] Figure 5 The image shows a scanning electron microscope (SEM) image of the transfer film on the metal-pair surface after the tribological performance test of the polymer self-lubricating composite material obtained in Example 1. Figure 5 A smooth and continuous transfer film was observed to form on the metal mating surface. The formation of the transfer film is attributed to the promoting effect of MOF-5, and the smooth transfer film also contributes to the improvement of the wear resistance of the composite material.

[0104] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing MOF-5, characterized in that, Includes the following steps: The zinc salt, terephthalic acid, capping agent, weak base and solvent are mixed and ultrasonically treated to obtain MOF-5; The end-capping agent is polyvinylpyrrolidone or polyvinyl alcohol; The weak base is triethylamine or sodium acetate; The zinc salt is zinc nitrate or zinc acetate; The solvent is N-methylpyrrolidone; The ultrasonic treatment has a power of 500~800W and a duration of 20~60min; The mass ratio of the zinc salt to terephthalic acid is 5~20:2~6; The mass ratio of terephthalic acid to end-capping agent is 2~6:0~6, and the mass of end-capping agent is not 0; The mass ratio of terephthalic acid to weak base is 2~6:0~5, and the mass of weak base is not 0; The mass ratio of the zinc salt to the solvent is 5~20:100; The MOF-5 has a lamellar morphology and a particle size of 1~5μm.

2. MOF-5 prepared by the method of claim 1.

3. The application of MOF-5 as described in claim 2 in polymer self-lubricating composite materials.

4. A polymer self-lubricating composite material, characterized in that, It includes MOF-5 and polyetheretherketone, wherein the MOF-5 is the MOF-5 as described in claim 2.

5. The polymer self-lubricating composite material according to claim 4, characterized in that, The mass ratio of polyetheretherketone (PEEK) to MOF-5 is 33.6:0.3~3.

5.

6. The method for preparing the polymer self-lubricating composite material according to any one of claims 4 to 5, characterized in that, Includes the following steps: Polyether ether ketone and MOF-5 were mixed and hot-pressed to obtain the polymer self-lubricating composite material.

7. The application of the polymer self-lubricating composite material according to any one of claims 4 to 5 or the polymer self-lubricating composite material prepared by the preparation method according to claim 6 in sliding bearings, gas compressors or automotive braking systems.

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