Metal organic framework piezoelectric material, preparation method thereof and application of metal organic framework piezoelectric material in atom transfer radical polymerization
By preparing metal-organic framework materials, constructing local non-centrosymmetric structures and introducing variable-valence metal sites, the piezoelectric catalysis and activation functions are integrated, which solves the low efficiency and pollution problems of existing piezoelectric materials in atom transfer radical polymerization and realizes an efficient and low-cost polymerization process.
Patent Information
- Application Number
- CN202510790143.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-13
- Publication Date
- 2025-09-16
AI Technical Summary
Existing piezoelectric materials have problems in catalyzing atom transfer radical polymerization, such as low efficiency, serious transition metal residual contamination, poor compatibility and limited large-scale application, making it difficult to meet the needs of green synthesis and industrial production.
By preparing metal-organic framework materials, using polar metal oxygen clusters and bipyridine organic ligands to construct a local non-centrosymmetric structure, introducing variable valence metal sites, realizing the integration of piezoelectric catalysis and activation functions, and using ultrasound-driven atom transfer radical polymerization to avoid the additional addition of consumable metal complexes.
Efficiently drive atom transfer radical polymerization at room temperature and pressure, reduce energy consumption, improve polymerization efficiency, broaden application scenarios, reduce metal residual pollution, and reduce production costs.
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Figure CN120647965A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of piezoelectric materials, and in particular relates to a metal organic framework piezoelectric material, a preparation method thereof, and an application thereof in atom transfer radical polymerization. Background Art
[0002] As an important material basis for the development of modern society, artificial synthetic polymer materials have deeply penetrated into various fields such as daily life, industrial manufacturing and cutting-edge technology. Their functional innovation is of urgent significance to meet social needs. Among the controllable polymer synthesis technologies, atom transfer radical polymerization, with its excellent "activity / controllability" characteristics, can accurately synthesize functional polymer materials with narrow molecular weight distribution and clear topological structure, and has become a research hotspot in the field of polymer chemistry. However, in traditional atom transfer radical polymerization technology, the thermal drive method relies on a high temperature environment (>80℃), and has problems such as high energy consumption, side reactions and material contamination caused by residual transition metal activators; although the light drive method can achieve activation at room temperature, its dependence on a specific wavelength light source, the easy degradation of photosensitizers and the limitation of light penetration (especially in heterogeneous systems) seriously restrict large-scale application. In recent years, piezoelectrically driven atom transfer radical polymerization, as an emerging strategy, drives free radical activation by stimulating the built-in electric field of piezoelectric materials through mechanical stress, showing significant advantages of no need for high temperature / light source and green energy saving. However, the key bottleneck of the current piezoelectric atom transfer radical polymerization technology lies in the insufficient efficiency of the catalytic system: traditional commercial piezoelectric materials (such as ZnO and BaTiO3) have problems such as low carrier mobility and poor conductivity, which leads to the need to add high doses of catalysts (4.5wt%-9wt%) during the reaction process to compensate for the insufficient electron transfer efficiency; at the same time, in order to activate the free radical initiation process, high concentrations of transition metal complexes (such as iron / copper salts and bipyridine, amine ligands, etc.) must be added as activators.
[0003] Metal-organic frameworks (MOFs) are a class of organic-inorganic hybrid materials with localized crystalline non-centrosymmetry, constructed from metal nodes and organic ligands through coordination bonds. They exhibit unique piezoelectricity, structural richness, and functional diversity, attracting the attention of researchers in fields such as piezoelectric catalysis. However, existing research on the piezoelectric properties of MOF piezoelectric materials (such as ZIF-8 and UiO-66) has focused solely on pollutant control, energy conversion, and piezoelectric nanogenerators, and lacks the ability to catalyze atom transfer radical polymerization (ATRP). Furthermore, their piezoelectric coefficients are much lower than those of traditional piezoelectric materials (such as ZnO and BaTiO3), and the resulting piezoelectric potential is insufficient to efficiently drive ATRP.
[0004] In summary, existing piezoelectric materials used for piezoelectrically driven atom transfer radical polymerization have the following shortcomings: First, the compatibility of multi-component systems is poor, and the interfacial synergy between transition metals and piezoelectric materials is weak, resulting in low initiation efficiency; second, metal residual contamination is serious, and it is difficult to completely separate the metal ions and ligands in the polymer product after the reaction, which not only affects the purity of the material but also poses a risk of secondary environmental pollution; third, large-scale application is limited, and high catalyst dosage and complex post-processing processes significantly increase production costs, making it difficult to meet the needs of green synthesis and industrial production. Therefore, it is urgent to develop piezoelectric materials that combine efficient piezoelectric response and catalytic-activation functions to break through the above technical bottlenecks. Summary of the Invention
[0005] To solve the above technical problems, the present invention provides a metal-organic framework piezoelectric material, a preparation method thereof, and an application in atom transfer radical polymerization. First, a metal hydrochloride and an organic ligand are mixed and ultrasonically dispersed uniformly, and then a metal-organic framework material is obtained through a high-temperature solvent thermal reaction. Then, a variable-valence metal active site is introduced into the organic ligand unit by post-modification with a transition metal hydrochloride to obtain a metal-organic framework material containing a variable-valence metal site.
[0006] The first object of the present invention is to provide a method for preparing a metal organic framework piezoelectric material, comprising the following steps:
[0007] S1, metal hydrochloride, organic ligand and coordination modifier react in a solvent to obtain a metal organic framework material;
[0008] The metal organic framework material described in S2 and S1 and the transition metal precursor react in an organic solvent to obtain the metal organic framework piezoelectric material.
[0009] In one embodiment of the present invention, in S1, the metal hydrochloride is selected from one or more of hafnium chloride, zirconium chloride, cerium chloride and ferric chloride;
[0010] The organic ligand is selected from 2,2'-bipyridine-5,5'-dicarboxylic acid and / or 2,2'-bipyridine-6,6'-dicarboxylic acid;
[0011] The coordination modifier is selected from one or more of benzoic acid, acetic acid, formic acid and water;
[0012] The solvent is selected from one or more of N,N-dimethylformamide, tetrahydrofuran, cyclohexanone and toluene;
[0013] The molar ratio of the metal hydrochloride to the organic ligand is 1:(0.5-1.5);
[0014] The volume ratio of the coordination modifier to the solvent is (0.5-2):4.
[0015] In one embodiment of the present invention, in S1, the reaction temperature is 140°C-160°C, and the reaction time is 12h-36h.
[0016] In one embodiment of the present invention, in S2, the transition metal precursor is selected from one or more of iron salts, copper salts, nickel salts, cobalt salts and ruthenium salts;
[0017] The organic solvent is selected from one or more of methanol, N,N-dimethylformamide and chloroform;
[0018] The mass ratio of the metal organic framework material to the transition metal precursor is 1:(1-1.8).
[0019] In one embodiment of the present invention, the iron salt is selected from ferric chloride and / or ferric bromide;
[0020] The copper salt is selected from one or more of copper chloride, copper bromide and copper iodide;
[0021] The nickel salt is nickel chloride;
[0022] The cobalt salt is selected from one or more of cobalt chloride, cobalt bromide and cobalt iodide;
[0023] The ruthenium salt is ruthenium chloride.
[0024] In one embodiment of the present invention, in S2, the reaction temperature is 70°C-90°C, and the reaction time is 12h-36h.
[0025] The second object of the present invention is to provide a metal organic framework piezoelectric material prepared by the method.
[0026] The third object of the present invention is to provide an application of the metal organic framework piezoelectric material in atom transfer radical polymerization, wherein the application process is as follows: under a protective atmosphere, methacrylate monomers, metal organic framework piezoelectric materials and initiators are subjected to atom transfer radical polymerization in a solvent to obtain a polymer material.
[0027] In one embodiment of the present invention, the methacrylate monomer is selected from one or more of methyl methacrylate, hydroxyethyl methacrylate, butyl methacrylate and hexyl methacrylate;
[0028] The initiator is selected from one or more of benzyl bromide, ethyl bromoacetate and ethyl α-bromoisobutyrate;
[0029] The solvent is selected from one or more of tetrahydrofuran, N,N-dimethylformamide and cyclopropanone;
[0030] The molar ratio of the methacrylate monomer to the initiator is 100:(0.5-1.5);
[0031] The mass ratio of the metal organic framework piezoelectric material to the methacrylate monomer is 1:(22-38).
[0032] In one embodiment of the present invention, the power of the atom transfer radical polymerization is 300W-600W, and the frequency is 40kHz-80kHz.
[0033] In one embodiment of the present invention, before performing atom transfer radical polymerization, three freeze-evacuation-thaw-air intake cycles are performed in a liquid nitrogen bath to remove air until no bubbles are generated, and then a protective atmosphere is introduced to put the reaction system in a water-free and oxygen-free state, and then the system is transferred to an ultrasonic machine for piezoelectrically driven atom transfer radical polymerization.
[0034] The technical solution of the present invention has the following advantages over the prior art:
[0035] (1) The metal organic framework piezoelectric material described in the present invention, on the one hand, is characterized by the abundant polar bonds in polar metal oxygen clusters. The introduction of polar metal oxygen clusters as metal nodes can promote the formation of a local non-centrosymmetric structure in the metal organic framework material. This not only gives the material intrinsic piezoelectricity, but also significantly improves the carrier separation efficiency by constructing a polar microenvironment, thereby generating enhanced piezoelectric catalytic activity. On the other hand, the bipyridine organic ligand containing nitrogen atoms is a type of ligand with strong coordination ability and stable structure. It can form a stable metal complex with transition metals and serve as an activation center for atom transfer radical polymerization. This enables the metal organic framework piezoelectric material to break away from its dependence on high temperature / light source. By driving with mechanical energy (such as ultrasound), a polymer material with a narrow molecular weight distribution (PDI≤1.3) and controllable structure can be synthesized under mild conditions, systematically solving the bottleneck problems of low efficiency of piezoelectric materials, residual transition metal catalysts and high energy consumption in the prior art.
[0036] (2) The metal organic framework piezoelectric material of the present invention directly drives the valence metal (such as Fe) on the surface of the piezoelectric material through the piezoelectric potential generated by the ultrasonic induction metal organic framework material. 2+ / Fe 3+ 、Cu + / Cu 2+) reversible valence state transition, a process that can efficiently initiate atom transfer radical polymerization. Therefore, without the need to add additional consumable metal complexes as activators, an "active / controllable" atom transfer radical polymerization process can be driven. Compared with traditional piezoelectric catalytic systems, this material replaces the transition metal complexes that need to be added exogenously (such as CuBr, bipyridine, etc.), effectively inhibiting the phenomenon of free radicals being consumed during the transfer between catalytic and activation sites, thereby reducing the catalyst dosage and improving the polymerization efficiency.
[0037] (3) The metal-organic framework piezoelectric material described in the present invention exhibits significant advantages in atom transfer radical polymerization (ATRP): it only requires mechanical energy (such as ultrasound) to drive the reaction, and can operate efficiently at room temperature and pressure without relying on high temperature (>80°C) or specific wavelength light sources. At the same time, it reduces the excessive use of metals and lowers energy consumption. It is particularly suitable for heterogeneous, dark or light-shielding systems, thereby significantly broadening the application scenarios.
[0038] (4) The preparation method described in the present invention utilizes the ligand-rich skeleton structure of the metal-organic framework material to provide a large number of anchoring sites for the transition metal. Through a simple method, the transition metal activation center can be directly combined with the metal-organic framework material to achieve the integration of piezoelectric catalysis and activation functions. BRIEF DESCRIPTION OF THE DRAWINGS
[0039] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:
[0040] Figure 1 Schematic diagram of the synthesis route of the metal-organic framework piezoelectric material of Example 1 of the present invention. DETAILED DESCRIPTION
[0041] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.
[0042] Example 1
[0043] Reference Figure 1 As shown, the metal organic framework piezoelectric material and the preparation method thereof of this embodiment specifically include the following steps:
[0044] S1. Add 1.2 mL of deionized water and 1.8 mmol of hafnium tetrachloride to the reactor until completely dissolved; continue to add 24 mL of N, N-dimethylformamide, 1.8 mmol of 2,2'-bipyridine-5,5'-dicarboxylic acid and 6 mL of formic acid, after ultrasonic dispersion for 5 minutes, place in a 150 ° C oven to react for 24 hours, after cooling to room temperature, collect the white solid powder by centrifugation; then add 24 mL of N, N-dimethylformamide and stir at 80 ° C for 24 hours to remove the unreacted metal hydrochloride and organic ligand, cool to room temperature, collect the solid powder by centrifugation, wash three times with 15 mL of chloroform, and place in a vacuum oven at 80 ° C to dry for 12 hours to obtain a metal organic framework material (UiO67-bpy);
[0045] S2. Under a nitrogen atmosphere, 200 mg of metal-organic framework material (UiO67-bpy), 30 mL of methanol / chloroform (volume ratio of 1:1) and 1.3 mmol of ferric chloride hexahydrate (FeCl3·6H2O) were added to a single-necked flask in sequence and ultrasonically dispersed for 5 minutes. The mixture was then placed in an 80°C oil bath for reflux reaction for 24 hours. After the reaction was completed, it was naturally cooled to room temperature. The precipitate at the bottom was collected by filtration and washed with methanol until the filtrate was colorless to obtain a metal-organic framework piezoelectric material, namely UiO67-Febpy.
[0046] Example 2
[0047] The metal organic framework piezoelectric material and the preparation method thereof of this embodiment specifically include the following steps:
[0048] S1. Add 1.2 mL of deionized water and 1.8 mmol of hafnium tetrachloride to the reactor until completely dissolved; continue to add 24 mL of N, N-dimethylformamide, 1.8 mmol of 2,2'-bipyridine-5,5'-dicarboxylic acid and 6 mL of formic acid, after ultrasonic dispersion for 5 minutes, place in a 150 ° C oven to react for 24 hours, after cooling to room temperature, collect the white solid powder by centrifugation; then add 24 mL of N, N-dimethylformamide and stir at 80 ° C for 24 hours to remove the unreacted metal hydrochloride and organic ligand, cool to room temperature, collect the solid powder by centrifugation, wash three times with 15 mL of chloroform, and place in a vacuum oven at 80 ° C to dry for 12 hours to obtain a metal organic framework material (UiO67-bpy);
[0049] S2. Under a nitrogen atmosphere, 200 mg of metal-organic framework material (UiO67-bpy), 30 mL of methanol / chloroform (volume ratio 1:1) and 1.3 mmol of copper chloride dihydrate (CuCl2·2H2O) were added to a single-necked flask in sequence and ultrasonically dispersed for 5 minutes. The mixture was then placed in an 80°C oil bath for reflux reaction for 24 hours. After the reaction was completed, it was naturally cooled to room temperature. The precipitate at the bottom was collected by filtration and washed with methanol until the filtrate was colorless to obtain a metal-organic framework piezoelectric material, namely UiO67-Cubpy.
[0050] Example 3
[0051] The metal organic framework piezoelectric material and the preparation method thereof of this embodiment specifically include the following steps:
[0052] S1. Add 1.2 mL of deionized water and 1.8 mmol of hafnium tetrachloride to the reactor until completely dissolved; continue to add 24 mL of N, N-dimethylformamide, 1.8 mmol of 2,2'-bipyridine-5,5'-dicarboxylic acid and 6 mL of formic acid, after ultrasonic dispersion for 5 minutes, place in a 150 ° C oven to react for 24 hours, after cooling to room temperature, collect the white solid powder by centrifugation; then add 24 mL of N, N-dimethylformamide and stir at 80 ° C for 24 hours to remove the unreacted metal hydrochloride and organic ligand, cool to room temperature, collect the solid powder by centrifugation, wash three times with 15 mL of chloroform, and place in a vacuum oven at 80 ° C to dry for 12 hours to obtain a metal organic framework material (UiO67-bpy);
[0053] S2. Under a nitrogen atmosphere, 200 mg of metal-organic framework material (UiO67-bpy), 30 mL of methanol / chloroform (volume ratio of 1:1) and 1.3 mmol of nickel chloride dihydrate (NiCl2·6H2O) were added to a single-necked flask in sequence and ultrasonically dispersed for 5 minutes. The mixture was then placed in an 80°C oil bath for reflux reaction for 24 hours. After the reaction was completed, it was naturally cooled to room temperature. The precipitate at the bottom was collected by filtration and washed with methanol until the filtrate was colorless to obtain a metal-organic framework piezoelectric material, namely UiO67-Nibpy.
[0054] Comparative Example 1
[0055] Piezoelectric material zinc oxide.
[0056] Comparative Example 2
[0057] Piezoelectric material barium titanate.
[0058] Comparative Example 3
[0059] Piezoelectric material metal organic framework material (UiO67-bpy).
[0060] Test Example 1
[0061] 50 mg of the piezoelectric material of Example 1-3 and Comparative Example 1-3, 0.11 mmol (16 μL) of initiator α-ethyl bromoisobutyrate, 11 mmol of methacrylate monomer methyl methacrylate and 2 mL of N, N-dimethylformamide were added to the Schlenk reaction tube and uniformly dispersed (specifically, about 0.07 mmol of copper bromide and 30 μL of tris(2-pyridylmethyl)amine were additionally added during the piezoelectrically driven atom transfer radical polymerization of Comparative Example 1-3), and then three freeze-evacuation-thaw-air intake cycles were performed in a liquid nitrogen bath (77 K) to remove the air in the reaction tube until no bubbles were generated, and then nitrogen was introduced to put the reaction system in an inert gas protection state. The reaction system was transferred to an ultrasonic machine (42 kHz, 300 W) for piezoelectrically driven atom transfer radical polymerization for 2 h. After the reaction was completed, it was precipitated by anhydrous ether to obtain a polymer material.
[0062] According to the GB / T 36214.1-2018 method, the number average molecular weight and molecular weight distribution of the polymer material obtained by piezoelectrically driven atom transfer radical polymerization were characterized by gel permeation chromatography (GPC). Specifically, the polymer material was mixed with tetrahydrofuran to prepare a 10 mg / L polymer solution, which was injected into the gel permeation chromatograph through an injector with an injection volume of 1.0 mL. Tetrahydrofuran was selected as the mobile phase, the flow rate was set to 1.0 mL / min, and polymethyl methacrylate was selected as the internal standard substance. The number average molecular weight and molecular weight distribution of the prepared polymer material were tested. The results are shown in Table 1:
[0063] Table 1
[0064] Group Number average molecular weight (kDa) Molecular weight distribution Example 1 58.3 1.2 Example 2 12.3 1.3 Example 3 28.4 1.3 Comparative Example 1 8.5 1.4 Comparative Example 2 4.1 1.4 Comparative Example 3 42.3 2.7
[0065] As can be seen from Table 1, using the metal-organic framework materials (Piezo-MOFs-M) containing variable-valence metal sites of Examples 1-3 as the catalytic system, the number-average molecular weight of the polymer materials obtained after polymerization was significantly increased, and the polymerization process remained controllable. This is because the piezoelectric materials of the examples achieve the dual functions of piezoelectric catalysis and metal activation, reducing the consumption of free radicals during the transfer process and improving the polymerization efficiency.
[0066] Using the commercial piezoelectric materials (ZnO, BaTiO3) of Comparative Examples 1-2, copper bromide, and tris(2-pyridylmethyl)amine as the catalytic system, the polymer materials obtained after polymerization had a low number-average molecular weight (4.1 kDa-8.5 kDa), indicating low polymerization efficiency of the commercial piezoelectric materials, while the polymerization process remained controllable. This is because the catalytic sites of the piezoelectric materials of Comparative Examples 1-2 and the activation sites of the metal complex have a certain degree of steric hindrance, resulting in chain transfer during the free radical transfer process generated by the initiator cleavage, resulting in low polymerization efficiency.
[0067] The polymerization process was uncontrollable using UiO67-bpy as the catalytic system in Comparative Example 3. This is because UiO67-bpy lacks an effective valence-varying metal site as an activation center, making it impossible to achieve a controllable polymerization process.
[0068] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.
Claims
1. A method for preparing a metal organic framework piezoelectric material, characterized in that: The following steps are involved: S1, metal hydrochloride, organic ligand and coordination modifier react in a solvent to obtain a metal organic framework material; The metal organic framework material described in S2 and S1 and the transition metal precursor react in an organic solvent to obtain the metal organic framework piezoelectric material.
2. The method for preparing a metal organic framework piezoelectric material according to claim 1, characterized in that: In S1, the metal hydrochloride is selected from one or more of hafnium chloride, zirconium chloride, cerium chloride and ferric chloride; The organic ligand is selected from 2,2'-bipyridine-5,5'-dicarboxylic acid and / or 2,2'-bipyridine-6,6'-dicarboxylic acid; The coordination modifier is selected from one or more of benzoic acid, acetic acid, formic acid and water; The solvent is selected from one or more of N,N-dimethylformamide, tetrahydrofuran, cyclohexanone and toluene; The molar ratio of the metal hydrochloride to the organic ligand is 1:(0.5-1.5); The volume ratio of the coordination modifier to the solvent is (0.5-2):
4.
3. The method for preparing a metal organic framework piezoelectric material according to claim 1, wherein: In S1, the reaction temperature is 140°C-160°C, and the reaction time is 12h-36h.
4. The method for preparing a metal organic framework piezoelectric material according to claim 1, wherein: In S2, the transition metal precursor is selected from one or more of iron salts, copper salts, nickel salts, cobalt salts and ruthenium salts; The organic solvent is selected from one or more of methanol, N,N-dimethylformamide and chloroform; The mass ratio of the metal organic framework material to the transition metal precursor is 1:(1-1.8).
5. The method for preparing a metal organic framework piezoelectric material according to claim 4, characterized in that: The iron salt is selected from ferric chloride and / or ferric bromide; The copper salt is selected from one or more of copper chloride, copper bromide and copper iodide; The nickel salt is nickel chloride; The cobalt salt is selected from one or more of cobalt chloride, cobalt bromide and cobalt iodide; The ruthenium salt is ruthenium chloride.
6. The method for preparing a metal organic framework piezoelectric material according to claim 1, characterized in that: In S2, the reaction temperature is 70°C-90°C, and the reaction time is 12h-36h.
7. A metal organic framework piezoelectric material prepared by the method according to any one of claims 1 to 6.
8. Use of the metal organic framework piezoelectric material according to claim 7 in atom transfer radical polymerization, characterized in that: The application process is: under a protective atmosphere, methacrylate monomers, metal organic framework piezoelectric materials and initiators are subjected to atom transfer radical polymerization in a solvent to obtain a polymer material.
9. The method for preparing a metal organic framework piezoelectric material according to claim 8, characterized in that: The methacrylate monomer is selected from one or more of methyl methacrylate, hydroxyethyl methacrylate, butyl methacrylate and hexyl methacrylate; The initiator is selected from one or more of benzyl bromide, ethyl bromoacetate and ethyl α-bromoisobutyrate; The solvent is selected from one or more of tetrahydrofuran, N,N-dimethylformamide and cyclopropanone; The molar ratio of the methacrylate monomer to the initiator is 100:(0.5-1.5); The mass ratio of the metal organic framework piezoelectric material to the methacrylate monomer is 1:(22-38).
10. The method for preparing a metal organic framework piezoelectric material according to claim 8, characterized in that: The power of the atom transfer radical polymerization is 300W-600W, and the frequency is 40kHz-80kHz.