A cross-linked polyaryl piperidine anion exchange membrane, a preparation method and application thereof

Abstract

The application discloses a cross-linked polyaryl piperidine anion exchange membrane and a preparation method and application thereof, and relates to the technical field of anion exchange membranes. The anion exchange membrane takes polyaryl piperidine as a skeleton, introduces crown ether structure and a cross-linked network, and solves the technical problem that the balance between the hydroxyl ion conductivity and the dimensional stability is difficult in the existing anion exchange membrane. The anion exchange membrane comprises a specific structure of a repeating unit, is prepared through Friedel-Crafts superacid catalytic polymerization, Menshutkin reaction functionalization and Michael addition reaction cross-linking, and has excellent hydroxyl ion conductivity, dimensional stability, chemical stability and mechanical strength. The preparation method is simple in operation, fast in polymerization rate, and high in conversion rate, does not need to strictly control the temperature and oxygen of a reaction environment, is suitable for the field of water electrolysis hydrogen production, especially suitable for an anion exchange membrane water electrolysis system, and has a wide industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of anion exchange membrane technology, specifically to a cross-linked polyarylpiperidine anion exchange membrane and its preparation method, and also to the application of this anion exchange membrane in the field of water electrolysis for hydrogen production. Background Technology

[0002] As the global energy structure shifts towards clean energy, hydrogen energy, as an efficient, clean, and sustainable energy carrier, is experiencing continuous market demand growth. Anion exchange membrane electrolysis (AEMWE) technology, with its combination of the low-cost advantages of alkaline water electrolysis and the high-efficiency dynamic response characteristics of proton exchange membrane water electrolysis, has become a research hotspot in the hydrogen production field. It has gradually moved from laboratory research to the industrialization stage, demonstrating enormous development potential.

[0003] Anion exchange membranes (AEMs) are the core component of the AEMWE system. Their main function is to isolate the gases (hydrogen and oxygen) generated at the anode and cathode, while efficiently conducting hydroxide ions (OH-). - Hydroxide ions facilitate ion migration and charge balance. Anion exchange membranes typically consist of a rigid polymer backbone and cationic groups. The polymer backbone provides the membrane with the necessary mechanical strength and chemical stability, while the cationic groups are responsible for the conduction of hydroxide ions. The synergistic effect of these two components directly determines the overall performance of the membrane. Currently, commercially available anion exchange membranes are mostly based on polyarylene piperidine structures. These membrane materials possess excellent chemical stability and high ionic conductivity, but they generally face a technical bottleneck: balancing hydroxide conductivity with dimensional stability. Increasing conductivity often requires increasing the membrane's water absorption rate, which leads to increased swelling and decreased dimensional stability, thus affecting the long-term operational reliability of the water electrolysis system.

[0004] To address the aforementioned balance issue, crosslinking technology is considered an effective strategy. By constructing a crosslinked network within the membrane, dimensional stability can be improved while maintaining high conductivity. In existing technologies, Young Moo Lee's team introduced 4-vinylbenzyl chloride into the polyarylene piperidine structure via the Menshutkin reaction, followed by free radical polymerization of the vinyl group during the casting process to form a crosslinked network. Xu Tongwen's team introduced 4-vinylbenzyl chloride into poly(p-terphenyl-co-m-terphenylpiperidine), also achieving crosslinking through free radical polymerization. However, these existing crosslinking methods still have several drawbacks: firstly, the degree of crosslinking is not clearly characterized, making it difficult to precisely control membrane performance; secondly, the free radical polymerization reaction has stringent requirements for temperature and oxygen content in the reaction environment, increasing the difficulty of industrial production; and thirdly, excessive use of 4-vinylbenzyl chloride can easily lead to membrane opacity, while the degree of crosslinking in existing processes is lower than the theoretical value, resulting in relatively high water absorption and swelling rates, which cannot fully meet the requirements of industrial applications.

[0005] Therefore, developing an anion exchange membrane that can precisely control the degree of crosslinking, balance high conductivity and excellent dimensional stability, and has a simple preparation process and is easy to industrialize has important practical significance and application value. Summary of the Invention

[0006] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a cross-linked polyarylpiperidine anion exchange membrane and its preparation method, so as to solve the technical problems such as the difficulty in balancing hydroxide conductivity and dimensional stability in existing anion exchange membranes, the complexity of existing cross-linking methods, and insufficient degree of cross-linking. At the same time, the present invention provides an application of the anion exchange membrane in the field of water electrolysis for hydrogen production, so as to meet the needs of industrial production and use.

[0007] To achieve the above objectives, the first aspect of the present invention provides a cross-linked polyarylpiperidine anion exchange membrane, characterized in that the anion exchange membrane has the structural formula shown in Formula I:

[0008] Formula I:

[0009] Wherein: Ar1 and Ar2 are each independently selected from arylene groups in aromatic compounds; R1 is selected from arylene or alkylene groups; R2 and R3 are each independently selected from methyl, methoxy, and ethoxy groups; m and n represent the molar percentage of the corresponding structural unit in the repeating unit, m+n=1, and 0<n≤0.4.

[0010] Preferably, Ar1 and Ar2 are each independently selected from one or more of the following structures:

[0011] (1) ;

[0012] (2) ;

[0013] (3) ;

[0014] (4) ;

[0015] (5) ;

[0016] (6) ;

[0017] (7) ;

[0018] (8) y = 0 - 5;

[0019] (9) ;

[0020] (10) ;

[0021] The aforementioned aryl structure is characterized by high rigidity and excellent chemical stability, which can provide the membrane with good mechanical strength and structural stability.

[0022] Preferably, R1 is selected from one of the following structures:

[0023] (1) ;

[0024] (2) Where x is a positive integer from 1 to 10, alkylene groups in this range can ensure crosslinking efficiency while avoiding a decrease in membrane rigidity due to excessively long carbon chains.

[0025] Preferably, R2 and R3 are each independently selected from -CH3, -OCH3, and -OCH2CH3.

[0026] Preferably, the polymer backbone of the anion exchange membrane is composed of ether-free aryl groups, which avoids the problem of easy degradation of ether bonds under alkaline conditions. The cationic group is a piperidine group and contains crown ether structural units, which can improve the service life of the membrane in alkaline electrolysis environment.

[0027] Preferably, the anion exchange membrane forms a cross-linked network through a Michael addition reaction. The formation process of the cross-linked network satisfies the following: the auxiliary cross-linking agent is activated by a catalyst to generate a carbanion nucleophile, which attacks the β-carbon atom on the halogen alkene monomer to form a new C-C bond.

[0028] Preferably, the anion exchange membrane contains a crown ether structure, wherein the crown ether structure is the structural unit corresponding to dibenzo-18-crown ether-6. The ether bond in the crown ether group is stable under alkaline conditions, which can increase the free volume inside the polymer. At the same time, it combines with water molecules to form a hydrated hydrogen ion-crown ether complex, thereby improving the water absorption rate and hydroxide ion conduction efficiency of the membrane, and further enhancing the conductivity of the membrane.

[0029] A second aspect of this invention provides a method for preparing a cross-linked polyarylpiperidine anion exchange membrane, comprising the following steps:

[0030] Step 1: Under the catalysis of a superacid, aromatic compounds undergo polymerization with N-methyl-4-piperidinone. After the reaction is completed, the precursor polymer is obtained by washing and drying.

[0031] Step 2: Dissolve the precursor polymer in a first solvent, add the halogen olefin monomer as shown in Formula II, and then add the functionalized monomer. The two monomers react sequentially with the piperidine ring in the precursor polymer in a Menshutkin reaction. After the reaction is completed, the polymer is obtained by precipitation, washing and drying.

[0032] Formula II: ;

[0033] Wherein, X is a halogen atom F, Cl, Br, or I; R1 is selected from arylene or alkylene groups;

[0034] Step 3: Dissolve the functionalized polymer in a second solvent, add the auxiliary crosslinking agent as shown in Formula III, stir evenly, and slowly add the catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The auxiliary crosslinking agent is activated by DBU to generate a carbanion nucleophile, which then attacks the β-carbon atom on the halogen alkene monomer shown in Formula II to undergo a Michael addition reaction, forming a crosslinked network. Cast the reaction solution and dry it to obtain a crosslinked polyarylpiperidine anion exchange membrane.

[0035] Formula III: ;

[0036] R4 and R5 are each independently selected from methyl, methoxy, and ethoxy.

[0037] Preferably, in step 1, the catalytic system for the polymerization reaction is a superacid, which is selected from one or more of trifluoromethanesulfonic acid, methanesulfonic acid, and trifluoroacetic acid; the aromatic compound includes an aromatic compound without ether bonds and a crown ether, with a molar ratio of 1:9. This ratio can ensure the rigidity of the membrane while fully leveraging the promoting effect of the crown ether group on ion conduction.

[0038] Preferably, in step 2, the halogen alkene monomer is 4-vinylbenzyl chloride, and the functionalized monomer is iodomethane; the essence of the Menshutkin reaction is that the nitrogen atom on the piperidine ring undergoes a nucleophilic substitution reaction with the halogen atom in the halogen alkene monomer and the functionalized monomer to form a quaternary ammonium salt structure.

[0039] Preferably, in step 3, the Michael addition reaction process satisfies the following: the carbanion nucleophile attacks the β-carbon atom on 4-vinylbenzyl chloride, and a nucleophilic addition reaction occurs to form a new C-C bond.

[0040] Preferably, in step 1, the molar ratio of the aromatic compound, N-methyl-4-piperidinone, and superacid is 1:(1.0-1.4):(8-15), the reaction temperature is 0-25℃, and the reaction time is 1-24h.

[0041] Preferably, in step 2, the molar ratio of the precursor polymer, halogenated olefin monomer, and functionalized monomer is 1:(0.1-0.5):(1-8), and the reaction temperature is 10-35℃.

[0042] Preferably, in step 3, the mass ratio of the functionalized polymer, the auxiliary crosslinking agent, and DBU is 1:(0.01-0.2):(0.001-0.02).

[0043] A third aspect of the present invention provides the application of the cross-linked polyarylpiperidine anion exchange membrane as described above or the cross-linked polyarylpiperidine anion exchange membrane prepared according to the aforementioned preparation method in the field of hydrogen production by water electrolysis.

[0044] Compared with the prior art, the technical effects of the present invention are as follows:

[0045] (1) The cross-linked polyarylpiperidine anion exchange membrane of the present invention achieves a good balance between hydroxide conductivity and dimensional stability by introducing a crown ether structure and optimizing the cross-linking pathway. The introduction of crown ether groups improves the water absorption rate and hydroxide ion conduction efficiency of the membrane, so that the conductivity of the membrane at 60°C is not less than 0.08 S / cm; the cross-linked network constructed by Michael addition reaction ensures that the gel fraction of the membrane is not less than 85% and the swelling rate is not more than 25%, significantly improving dimensional stability. At the same time, the polymer skeleton adopts an ether-free aryl structure and the cationic group is a piperidine group, which endows the membrane with excellent chemical stability and can be used for a long time in an alkaline electrolysis environment.

[0046] (2) The preparation method of the present invention adopts Friedel-Crafts superacid catalytic polymerization, which has a fast polymerization rate, high conversion rate, and simple operation; the functionalization of polymer and the introduction of crosslinking sites are achieved through the Menshutkin reaction, and the reaction conditions are mild; the crosslinking process adopts Michael addition reaction, which does not require strict control of temperature and oxygen content, reducing the difficulty of industrial production, and the degree of crosslinking is easy to control. In addition, the raw materials used in the preparation process are easy to obtain, the process steps are simple, and it is suitable for large-scale production.

[0047] (3) The application of the anion exchange membrane of the present invention in the field of hydrogen production by water electrolysis can significantly improve the efficiency and stability of the anion exchange membrane water electrolysis system, reduce the cost of hydrogen production, and promote the development of the hydrogen energy industry. It has important economic value and social significance.

[0048] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0049] Figure 1The surface morphology of the cross-linked crown ether-containing poly(biphenylpiperidine) anion exchange membrane prepared in Example 1 of the present invention is shown in the image (scanning electron microscope, magnification 10000x).

[0050] Figure 2 The surface morphology of the cross-linked crown ether-containing poly(p-terphenylpiperidine) anion exchange membrane prepared in Example 2 of the present invention is shown in the image (scanning electron microscope, magnification 10000x).

[0051] Figure 3 The surface morphology of the cross-linked crown ether-containing poly(m-terphenylpiperidine) anion exchange membrane prepared in Example 3 of the present invention is shown in the image (scanning electron microscope, magnification 10000x). Detailed Implementation

[0052] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0053] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0054] Example 1

[0055] This embodiment provides a method for preparing a cross-linked crown ether-containing polybisphenylpiperidine anion exchange membrane containing an auxiliary cross-linking agent and cross-linking groups accounting for 20% of the total content. The main chain structure is as follows:

[0056]

[0057] Where R is the crosslinking portion .

[0058] (1) Synthesis of polyarylpiperidine precursor polymers

[0059] Biphenyl (6.94 g, 45 mmol), dibenzo-18-crown ether-6 (1.80 g, 5 mmol), and N-methyl-4-piperidinone (6.224 g, 55 mmol) were dissolved in 19 mL of dichloromethane and stirred until homogeneous at 0 °C. Trifluoroacetic acid (4 mL) and trifluoromethanesulfonic acid (46 mL) were then added dropwise to a single-necked flask. The reaction was continued at 0–5 °C for 3 h. After the stir bar became inert, the resulting dark blue viscous liquid was poured into deionized water. The precipitate was precipitated, cut into small pieces, and washed three times with deionized water until the pH of the washing solution was adjusted to approximately 7. After filtration, the polymer was dried in a vacuum oven at 80 °C for 24 h to obtain the precursor polymer.

[0060] (2) Synthesis of functionalized polymers

[0061] The precursor polymer (5 g) was dissolved in 188 ml of DMSO at room temperature, and 4-vinylbenzyl chloride (0.978 g, 6.41 mmol) was added. The mixture was reacted at room temperature for 24 h, and then iodomethane (9.705 g, 68.38 mmol) was added. The reaction was continued for 48 h. After the reaction was completed, the reaction solution was poured into ethyl acetate to precipitate the polymer. The precipitate was washed three times with deionized water and dried in a vacuum oven at 80 °C for 24 h to obtain the functionalized polymer.

[0062] (3) Preparation of cross-linked anion exchange membranes

[0063] The functionalized polymer (5g) was dissolved in 167g DMSO, and ethyl acetoacetate (0.5g) was added as an auxiliary crosslinking agent. After stirring until homogeneous, 1,8-diazabicyclo[5.4.0]undec-7-ene (0.05g) was slowly added dropwise. The homogeneous solution was poured onto a clean glass plate and cast at 60℃. After the membrane was formed, it was placed at 80℃ and vacuum dried for 12h to obtain a crosslinked polyarylpiperidine anion exchange membrane.

[0064] Working Principle: The polymer backbone of this anion exchange membrane is composed of biphenyl groups and piperidine rings, exhibiting high rigidity and excellent chemical stability. Crown ether structural units increase the membrane's free volume and water absorption, promoting the combination of hydroxide ions and water molecules to form hydrated ions, thus accelerating ion conduction. The cross-linked network formed through the Michael addition reaction restricts polymer chain movement, reducing the membrane's swelling ratio without affecting the hydroxide ion conduction channels. During the electrolysis of water to produce hydrogen, the membrane effectively isolates the hydrogen generated at the cathode from the oxygen generated at the anode. Hydroxide ions are efficiently conducted from the anode to the cathode through the cation groups and hydrated channels within the membrane, achieving charge balance and ensuring the continuous progress of the electrolysis reaction.

[0065] Example 2

[0066] This embodiment provides a method for preparing a cross-linked crown ether-containing poly(p-terphenylpiperidine) anion exchange membrane containing an auxiliary cross-linking agent and cross-linking groups accounting for 20% of the total content. The main chain structure is as follows:

[0067]

[0068] Where R is the cross-linked structure .

[0069] (1) Synthesis of polyarylpiperidine precursor polymers

[0070] 10.36 g (45 mmol) of terphenyl, 1.80 g (5 mmol) of dibenzo-18-crown ether-6, and 6.224 g (55 mmol) of N-methyl-4-piperidinone were dissolved in 19 mL of dichloromethane and stirred at 0 °C until homogeneous. Then, 4 mL of trifluoroacetic acid and 46 mL of trifluoromethanesulfonic acid were added dropwise to a single-necked flask. The reaction was continued at 0–5 °C for 3 h. After the stir bar became inert, the resulting dark blue viscous liquid was poured into deionized water. The precipitate was precipitated, cut into small pieces, and washed three times with deionized water until the pH of the washing solution was adjusted to approximately 7. After filtration, the polymer was dried in a vacuum oven at 80 °C for 24 h to obtain the precursor polymer.

[0071] (2) Synthesis of functionalized polymers

[0072] The precursor polymer (5g) from step (1) was dissolved in 135ml DMSO at room temperature. 4-Vinylbenzyl chloride (0.704g, 4.62mmol) was added and reacted at room temperature for 24h. Then iodomethane (6.988g, 49.23mmol) was added and the reaction was continued for 48h. After the reaction was completed, the reaction solution was poured into ethyl acetate to precipitate the polymer. The polymer was washed three times with deionized water and dried in a vacuum oven at 80℃ for 24h to obtain the functionalized polymer.

[0073] (3) Preparation of cross-linked anion exchange membranes

[0074] The functionalized polymer (5g) was dissolved in 167g DMSO, and ethyl acetoacetate (0.5g) was added as an auxiliary crosslinking agent. After stirring until homogeneous, 1,8-diazabicyclo[5.4.0]undec-7-ene (0.05g) was slowly added dropwise. The homogeneous solution was poured onto a clean glass plate and cast at 60℃. After the membrane was formed, it was placed at 80℃ and vacuum dried for 12h to obtain a crosslinked polyarylpiperidine anion exchange membrane.

[0075] Working Principle: This preparation method achieves the preparation of anion exchange membranes through a three-step reaction. The first step is a Friedel-Crafts superacid-catalyzed polymerization reaction, utilizing the strong catalytic activity of mixed superacids to rapidly polymerize terphenyl, crown ethers, and N-methyl-4-piperidinone, forming a precursor polymer with a specific structure. This process is characterized by high polymerization rate and high conversion rate. The second step, the Menshutkin reaction, is carried out in two steps: first, crosslinking sites are introduced, followed by quaternization modification to achieve functionalization. The reaction conditions are mild and do not require strict environmental control. The third step is a Michael addition reaction crosslinking, where a DBU-activated auxiliary crosslinking agent reacts with the crosslinking sites to form a crosslinked network. This crosslinking pathway does not require temperature and oxygen control, is simple to operate, and allows for easy control of the degree of crosslinking, overcoming the shortcomings of existing free radical polymerization crosslinking methods.

[0076] Example 3

[0077] This embodiment provides a method for preparing a cross-linked crown ether-containing poly(m-terphenylpiperidine) anion exchange membrane containing an auxiliary cross-linking agent and cross-linking groups accounting for 20% of the total content. The main chain structure is as follows:

[0078]

[0079] Where R is the cross-linked structure .

[0080] (1) Synthesis of polyarylpiperidine precursor polymers

[0081] 10.36 g (45 mmol) of terphenyl, 1.80 g (5 mmol) of dibenzo-18-crown ether-6, and 6.224 g (55 mmol) of N-methyl-4-piperidinone were dissolved in 19 mL of dichloromethane and stirred at 0 °C until homogeneous. Then, 4 mL of trifluoroacetic acid and 46 mL of trifluoromethanesulfonic acid were added dropwise to a single-necked flask. The reaction was continued at 0–5 °C for 2.5 h. After the stir bar became inert, the resulting dark blue viscous liquid was poured into deionized water. The precipitate was precipitated, cut into small pieces, and washed three times with deionized water until the pH of the washing solution was adjusted to approximately 7. After filtration, the polymer was dried in a vacuum oven at 80 °C for 24 h to obtain the precursor polymer.

[0082] (2) Synthesis of functionalized polymers

[0083] The precursor polymer (5g) from step (1) was dissolved in 135ml DMSO at room temperature. 4-Vinylbenzyl chloride (0.704g, 4.62mmol) was added and reacted at room temperature for 24h. Then iodomethane (6.988g, 49.23mmol) was added and the reaction was continued for 48h. After the reaction was completed, the reaction solution was poured into ethyl acetate to precipitate the polymer. The polymer was washed three times with deionized water and dried in a vacuum oven at 80℃ for 24h to obtain the functionalized polymer.

[0084] (3) Preparation of cross-linked anion exchange membranes

[0085] The functionalized polymer (5g) was dissolved in 167g DMSO, and ethyl acetoacetate (0.5g) was added as an auxiliary crosslinking agent. After stirring until homogeneous, 1,8-diazabicyclo[5.4.0]undec-7-ene (0.05g) was slowly added dropwise. The homogeneous solution was poured onto a clean glass plate and cast at 60℃. After the membrane was formed, it was placed at 80℃ and vacuum dried for 12h to obtain a crosslinked polyarylpiperidine anion exchange membrane.

[0086] Comparative Example 1

[0087] This embodiment provides a method for preparing a cross-linked poly(biphenylpiperidine) anion exchange membrane with a cross-linking group accounting for 20% of the total content, and the structural formula is as follows:

[0088] .

[0089] The precursor polymer and functionalized polymer were obtained in the same manner as in Example 1. The obtained functionalized polymer (1.8 g) was then dissolved in 60 g of DMSO. After stirring completely, the solution was poured onto a clean glass plate and cast at 60 °C. After the membrane was formed, it was placed at 80 °C and vacuum dried for 12 h to obtain a cross-linked polydiphenylpiperidine anion exchange membrane.

[0090] Comparative Example 2

[0091] This embodiment provides a method for preparing a cross-linked poly(p-terphenylpiperidine) anion exchange membrane with a cross-linking group accounting for 20% of the total content, and the structural formula is as follows:

[0092] .

[0093] The precursor polymer and functionalized polymer were obtained in the same manner as in Example 2. The obtained functionalized polymer (1.8 g) was then dissolved in 60 g of DMSO. After stirring completely, the solution was poured onto a clean glass plate and cast at 60 °C. After the membrane was formed, it was placed at 80 °C and vacuum dried for 12 h to obtain a cross-linked poly(p-terphenylpiperidine) anion exchange membrane.

[0094] Comparative Example 3

[0095] This embodiment provides a method for preparing a cross-linked poly(m-terphenylpiperidine) anion exchange membrane with a cross-linking group accounting for 20% of the total content, and the structural formula is as follows:

[0096] .

[0097] The precursor polymer and functionalized polymer were obtained in the same manner as in Example 1. The obtained functionalized polymer (1.8 g) was then dissolved in 60 g of DMSO. After stirring completely, the solution was poured onto a clean glass plate and cast at 60 °C. After the membrane was formed, it was placed at 80 °C and vacuum dried for 12 h to obtain a cross-linked poly(m-terphenylpiperidine) anion exchange membrane.

[0098] The products obtained from the examples and comparative examples were experimentally compared:

[0099] (1) Gel fraction (GF)

[0100] Cut the crosslinked membrane into 1cm x 2cm pieces and weigh the membrane. The membrane was then immersed in N,N-dimethylformamide solvent and placed in an oven at 80°C for 24 hours. After being completely dried, the membrane was weighed. The gel fraction of the cross-linked membrane is calculated using formula (1):

[0101] (1)

[0102] (2) Water absorption rate and swelling rate

[0103] The membrane was cut into 4cm × 1cm pieces and immersed in 1M NaOH solution at 60℃ for 24 hours for ion exchange, with the alkali solution replaced every 8 hours. After complete exchange, the membrane surface was rinsed with ultrapure water to remove the alkali solution, and then dried in a vacuum oven at 80℃ for 24 hours. The membrane sample was then removed, and the diagonal length of the membrane in the dry state was measured. ) and quality ( Subsequently, the membrane was placed in nitrogen-saturated ultrapure water and soaked at the corresponding temperature for 24 hours. The membrane sample was then removed, and its wet diagonal length at the corresponding temperature was quickly measured. Then, gently wipe away the water on its surface with lens paper and weigh its wet mass. The water absorption rate (WU) and swelling ratio (SR) of the membrane sample can be calculated according to formulas (2) and (3):

[0104] (2)

[0105] (3)

[0106] in, and These represent the diagonal length and mass of the dry film, respectively. and These refer to the diagonal length and mass of the wet film at the corresponding temperature, respectively.

[0107] (3) Hydroxide ion conductivity

[0108] The membrane was cut into 1cm × 4cm pieces and immersed in 1M NaOH solution at 60℃ for 24h for ion exchange, with the alkali solution being replaced every 8h. After complete exchange, the alkali solution on the membrane surface was rinsed off with ultrapure water, and the membrane was assembled into a conductivity testing fixture. The fixture was then placed in ultrapure water and nitrogen gas was continuously introduced. The potentiostatic impedance of the anion exchange membrane was tested using a Gamry electrochemical workstation, and the impedance was calculated using formula (4). Electrical conductivity:

[0109] (4)

[0110] in, Represents proton conductivity (S L represents the distance between the electrodes ( R represents the measured high-frequency impedance (kΩ), and A represents the effective area of ​​the membrane perpendicular to the electrode. ).

[0111] The basic data of the above embodiments are summarized in Table 1:

[0112] Table 1 Summary of Basic Data

[0113]

[0114] (4) Electrolysis performance of anion exchange membranes

[0115] NiFe or Pt / Ru / C catalysts are uniformly mixed with their corresponding ionomers in an isopropanol solution and fully dispersed. The catalyst ink is then sprayed onto the current collector, where the NiFe catalyst loading is 4.0%. The load on Pt / Ru / C is 1.0. The above steps were used to fabricate the membrane electrode. Using 1M KOH solution as fuel, polarization curves were recorded using a battery test station within the applied voltage range of 1.3 V to 2.0 V to investigate the membrane-based AEMW performance.

[0116] Table 2 summarizes the performance of AEMWE in the above embodiments:

[0117] Table 2 Summary of AEMWE Performance

[0118]

[0119] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A cross-linked polyarylpiperidine anion exchange membrane, characterized in that, The structural formula of the anion exchange membrane is shown in Formula I: Formula I: Wherein: Ar1 and Ar2 are each independently selected from arylene groups in aromatic compounds; R1 is selected from arylene or alkylene groups; R2 and R3 are each independently selected from methyl, methoxy, and ethoxy groups; m and n represent the molar percentage of the corresponding structural unit in the repeating unit, m+n=1, and 0<n≤0.

4.

2. The cross-linked polyarylpiperidine anion exchange membrane according to claim 1, characterized in that, Ar1 and Ar2 are each independently selected from one or more of the following structures: （1） ； （2） ； （3） ； （4） ； （5） ； （6） ； （7） ； （8） ，y=0-5； （9） ； （10） 。 3. The cross-linked polyarylpiperidine anion exchange membrane according to claim 1, characterized in that, R1 is selected from one of the following structures: （1） ； (2) , where x is a positive integer from 1 to 10.

4. The cross-linked polyarylpiperidine anion exchange membrane according to claim 1, characterized in that, R2 and R3 are each independently selected from -CH3, -OCH3, and -OCH2CH3.

5. The cross-linked polyarylpiperidine anion exchange membrane according to claim 1, characterized in that, The polymer backbone of the anion exchange membrane is composed of ether-free aryl groups, the cationic group is a piperidine group, and it contains crown ether structural units.

6. The cross-linked polyarylpiperidine anion exchange membrane according to claim 1, characterized in that, The anion exchange membrane forms a cross-linked network through a Michael addition reaction. The formation process of the cross-linked network satisfies the following: the auxiliary cross-linking agent is activated by a catalyst to generate a carbanion nucleophile, which attacks the β-carbon atom on the halogen alkene monomer to form a new C-C bond.

7. A method for preparing a cross-linked polyarylpiperidine anion exchange membrane, characterized in that, Includes the following steps: Step 1: Under the catalysis of a superacid, aromatic compounds undergo polymerization with N-methyl-4-piperidinone. After the reaction is completed, the precursor polymer is obtained by washing and drying. Step 2: Dissolve the precursor polymer in a first solvent, add the halogen olefin monomer as shown in Formula II, and then add the functionalized monomer. The two monomers react sequentially with the piperidine ring in the precursor polymer in a Menshutkin reaction. After the reaction is completed, the polymer is obtained by precipitation, washing and drying. Formula II: ; Wherein, X is a halogen atom F, Cl, Br, or I; R1 is selected from arylene or alkylene groups; Step 3: Dissolve the functionalized polymer in a second solvent, add the auxiliary crosslinking agent as shown in Formula III, stir evenly, and slowly add the catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The auxiliary crosslinking agent is activated by DBU to generate a carbanion nucleophile, which then attacks the β-carbon atom on the halogen alkene monomer shown in Formula II to undergo a Michael addition reaction, forming a crosslinked network. Cast the reaction solution and dry it to obtain a crosslinked polyarylpiperidine anion exchange membrane. Formula III: ; R4 and R5 are each independently selected from methyl, methoxy, and ethoxy.

8. The preparation method according to claim 7, characterized in that, In step 1, the catalytic system for the polymerization reaction is a superacid, which is selected from one or more of trifluoromethanesulfonic acid, methanesulfonic acid, and trifluoroacetic acid; the aromatic compounds include aromatic compounds without ether bonds and crown ethers, with a molar ratio of 1:

9.

9. The preparation method according to claim 7, characterized in that, In step 2, the halogen alkene monomer is 4-vinylbenzyl chloride, and the functionalized monomer is iodomethane. The essence of the Menshutkin reaction is that the nitrogen atom on the piperidine ring undergoes a nucleophilic substitution reaction with the halogen atom in the halogen alkene monomer and the functionalized monomer to form a quaternary ammonium salt structure.

10. The preparation method according to claim 7, characterized in that, In step 3, the auxiliary crosslinking agent is ethyl acetoacetate.

11. The preparation method according to claim 7, characterized in that, In step 3, the Michael addition reaction process satisfies the following: the carbanion nucleophile attacks the β-carbon atom on 4-vinylbenzyl chloride, and a new C-C bond is formed through nucleophilic addition.

12. The preparation method according to claim 7, characterized in that, In step 1, the molar ratio of aromatic compound, N-methyl-4-piperidinone and superacid is 1:(1.0-1.4):(8-15), the reaction temperature is 0-25℃, and the reaction time is 1-24h.

13. The preparation method according to claim 7, characterized in that, In step 2, the molar ratio of the precursor polymer, halogenated olefin monomer, and functionalized monomer is 1:(0.1-0.5):(1-8), and the reaction temperature is 10-35℃.

14. The preparation method according to claim 7, characterized in that, In step 3, the mass ratio of functionalized polymer, auxiliary crosslinking agent and DBU is 1:(0.01-0.2):(0.001-0.02).

15. The application of a cross-linked polyarylpiperidine anion exchange membrane as described in any one of claims 1-6 or a cross-linked polyarylpiperidine anion exchange membrane prepared by the preparation method as described in any one of claims 7-14 in the field of hydrogen production by water electrolysis.

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