Polymer for preparing anion-exchange membrane with high alkali stability, anion-exchange membrane and preparation method of anion-exchange membrane

Abstract

The invention relates to a polymer for preparing an anion exchange membrane with high alkali stability, the anion exchange membrane and a preparation method of the anion exchange membrane. The polymer comprises a polystyrene main chain or a polystyrene-containing block copolymer main chain and a nitrogen heterocyclic monomer, the nitrogen heterocyclic ring monomer is bonded to the phenyl para-position on the polystyrene main chain or the polystyrene-containing block copolymer main chain through methylene. The ionic conductivity, alkali stability and long-term operation durability of the membrane are greatly improved, and the service life of the membrane is prolonged.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of anion exchange membrane materials, and particularly relates to a polymer for preparing a high-alkali-stability anion exchange membrane, an anion exchange membrane and a preparation method thereof. BACKGROUND

[0002] Anion exchange membrane electrolysis of water to produce hydrogen is a hydrogen production technology that uses an anion exchange membrane as an electrolyte and a transition metal as a catalytic electrode, and uses pure water or a low-concentration alkaline solution as an electrolyte, and has the advantages of low cost of alkaline electrolysis of water (ALK) and high current density of proton exchange membrane (PEM), and is attracting more and more research and industrial attention. However, although the anion exchange membrane technology has shown significant potential in the production of hydrogen by water electrolysis, it still faces a series of key technical challenges in the process of moving towards large-scale commercial application. In particular, under high-temperature working conditions and long-term continuous operation, the chemical stability of the traditional aryl polymer main chain in a strong alkali and high-temperature environment is insufficient, which directly affects the overall efficiency and service life of the system, therefore, the current research focus is on developing new high-performance anion exchange membrane materials, optimizing their chemical structure to enhance mechanical strength and stability, and improving the reliability of anion exchange membranes in harsh operating environments, so as to promote the overall progress and industrialization of green hydrogen production technology. SUMMARY

[0003] The present application aims to overcome the defects in the prior art, and provides a polymer for preparing a high-alkali-stability anion exchange membrane, an anion exchange membrane and a preparation method thereof, which greatly improves the ion conductivity, alkali stability and long-term operation durability of the membrane, and prolongs the service life thereof.

[0004] To achieve the above-mentioned object, the technical solutions adopted by the present application are as follows:

[0005] A polymer for preparing a high-alkali-stability anion exchange membrane, comprising a polystyrene main chain or a block copolymer containing polystyrene, and a nitrogen-free heterocyclic monomer, wherein the nitrogen-free heterocyclic monomer is bonded to the polystyrene main chain or the block copolymer containing polystyrene through a methylene group at the para position of the phenyl group.

[0006] As a further technical solution, the block copolymer containing polystyrene comprises any one of a styrene-butadiene-styrene block copolymer, an acrylonitrile-butadiene-styrene block copolymer, a styrene-acrylonitrile block copolymer, a styrene-methyl methacrylate block copolymer, and an acrylonitrile-styrene-acrylate block copolymer.

[0007] A polymer for preparing a high-alkali-stability anion exchange membrane, having a structural formula as shown in formula 1-6: ; In formula 1-6, x, y, z are the mole percentage of the corresponding block in the polymer; x+y+z=100%, 20%≤x≤100%, 0%≤y≤80%, 0%≤z≤60%; In formula 1-6, R is independently selected from any one of , , , , , , , , , , .

[0008] As a further technical solution, in formula 1, x=100%; in formula 2, 20%≤x≤100%, 76%≤y≤80, 40%≤z≤60%; in formula 3, 10%≤x≤30%, 20%≤y≤60%, 40%≤z≤60%; in formula 4, 40%≤x≤60%, 40%≤y≤60%; in formula 5, 40%≤x≤60%, 40%≤y≤60%; in formula 6, 10%≤x≤30%, 40%≤y≤60%, 40%≤z≤60%.

[0009] The preparation method of the above-mentioned polymer comprises the following steps: Under the condition of ice water bath, the main chain polymer and the unsaturated nitrogen heterocyclic monomer are dissolved in the first solvent, then stirred, and trifluoromethanesulfonic acid (TFSA) is added dropwise, and stirring is continued for at least 72h to obtain a viscous solution; then the viscous solution is poured into the second solvent to obtain a solid polymer; the residual excess acid of the solid polymer is washed with the first lye, and washed with deionized water for multiple times until neutral, and dried in a vacuum oven to obtain the polymer of any one of claims 1-4; the main chain polymer is polystyrene or a block copolymer containing polystyrene; As a further technical solution, the unsaturated nitrogen heterocyclic monomer includes any one of 4-vinylpiperidine hydrochloride, 4-vinylpiperidine hydrochloride, 3-vinylpiperidine hydrochloride, 4-methylene piperidine hydrochloride, 1,2,3,6, tetrahydropyridine hydrochloride, 3-vinylpiperidine hydrochloride, 2-vinylpiperidine hydrochloride, 3-methylene piperidine hydrochloride, N-vinylpyrrolidone hydrochloride, 2-vinylpiperidine hydrochloride, 3-methylene-1-azabicyclo[2.2.2]octane hydrochloride.

[0010] As a further technical solution, the molar ratio of the main chain polymer and the unsaturated nitrogen heterocyclic monomer is 1:0.3-0.5.

[0011] As a further technical solution, the molar ratio of the unsaturated nitrogen-containing heterocyclic monomer to trifluoromethanesulfonic acid is 1:8-20.

[0012] As a further technical solution, the first solvent is one or more of dichloromethane solution, trichloromethane, and 1,2-dichloroethane.

[0013] As a further technical solution, the second solvent is one or more of water, ethyl acetate, methanol, ethanol, diethyl ether, tetrahydrofuran, or acetone.

[0014] As a further technical solution, the first alkaline solution is any one of K2CO3 solution, KOH solution, NaOH solution, and NaHCO3 solution.

[0015] As a further technical solution, the concentration of the first alkaline solution is 0.5-2.0M.

[0016] A highly alkali-stable anion exchange membrane comprises a polystyrene backbone or a polystyrene-containing block copolymer backbone, and a nitrogen-containing heterocyclic cationic functional group on the polystyrene backbone or the polystyrene-containing block copolymer backbone, wherein the nitrogen-containing heterocyclic cationic functional group is selected from... , , , , , , , , , , Any one of them.

[0017] A method for preparing a highly alkali-stable anion exchange membrane, characterized in that it is prepared using the aforementioned polymer, and the preparation method includes the following steps: Step a: The polymer is dissolved in a third solvent, then K2CO3 and iodomethane are added, and the mixture is stirred at 40-50°C for at least 48 hours to obtain a viscous solution. The viscous solution is then poured into a fourth solvent to precipitate a white precipitate. The precipitate is then filtered, collected, washed with deionized water, and dried in a vacuum oven to obtain the quaternized polymer. Step b: Dissolve the obtained quaternized polymer in a fifth solvent, stir at 50-60℃, filter through a 0.25-0.45μm polytetrafluoroethylene (PTFE) filter, cast the solution onto a clean glass plate, and dry in an oven at 80-120℃ to obtain I. - Type I film; the obtained I - The membrane is peeled off and immersed in anion exchange solution for ion exchange to obtain a highly alkaline stable anion exchange membrane.

[0018] As a further technical solution, in step a, the mass volume of the polymer and the third solvent is 1g:(6-10)mL.

[0019] As a further technical solution, in step a, the third solvent is one or more of N,N-dimethylformamide, N,N-diethylformamide, N-methylpyrrolidone, and toluene.

[0020] As a further technical solution, in step a, the fourth solvent is ethyl acetate, methanol, ethanol, acetone, or diethyl ether.

[0021] As a further technical solution, in step b, the fifth solvent is one or more of N,N-dimethylformamide, N,N-diethylformamide, N-methylpyrrolidone, and toluene.

[0022] As a further technical solution, in step b, the mass volume of the quaternized polymer and the fifth solvent is 1g:(15-25)mL.

[0023] As a further technical solution, in step b, the anion exchange solution includes one or more of NaOH, KOH, NaCl, KCl, NaBr, KBr, Na2SO4, and Na2CO3.

[0024] As a further technical solution, in step b, the concentration of the anion exchange solution is 0.5-2.0M.

[0025] The application of the high-alkali-stability anion exchange membrane in anion exchange membrane water electrolysis for hydrogen production.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: The core advantage of this invention, which uses polystyrene or polystyrene-containing block polymers as the main chain, lies in providing a highly customizable and high-performance material platform: the intrinsic chemical inertness of the saturated carbon-carbon main chain of polystyrene can significantly resist the attack of hydroxide ions, fundamentally improving the alkaline stability of the membrane; through mature living polymerization technology, the sequence, molecular weight, and topology of the block copolymer can be precisely designed, thereby self-assembling within the membrane to form highly ordered and highly interconnected ion transport channels, achieving high ionic conductivity; its benzene ring structure can serve as a universal chemical "handle," modifying and grafting cationic monomers through double bond reactions. Compared with the traditional benzyl bond reaction grafting method, this greatly improves the stability, conductivity, and mechanical reliability of the anion exchange membrane, enhancing membrane performance and extending membrane life. Attached Figure Description

[0027] Figure 1The proton NMR spectrum of the anion exchange membrane of formula A3 prepared in Example 1;

[0028] Figure 2 The graphs show the change in conductivity over time for the anion exchange membranes prepared in Example 2 and Comparative Example 1. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] In this invention, Polystyrene: MV~192000, McLean; SEBS: MV~118000, Titan; ABS: MV~252000, McLean; ASA: MV~165000, Titan; Unless otherwise specified, all raw materials used in this invention are commercially available.

[0031] Example 1 The OH of the polystyrene-4-methylenepiperidine homopolymer shown in Formula A3 - Taking a type of anion exchange membrane as an example, this invention introduces a method for preparing an anion exchange membrane, the synthetic reaction route of which is as follows: ; An anion exchange membrane (OH- of polystyrene-4-methylenepiperidine homopolymer) - The preparation method of the anion exchange membrane includes the following steps: Step 1: In a three-necked flask, polystyrene (0.0384 mol, 4 g) and 4-methylenepiperidine hydrochloride (11.5 mmol, 1.53 g) were dissolved in 60 mL of dichloromethane. The system was slowly stirred using a PTFE two-blade stirrer and a mechanical stirrer to ensure uniform mixing of the reactants and dichloromethane solvent. Subsequently, trifluoromethanesulfonic acid (0.228 mol, 20 mL) was slowly added to the system using a constant pressure dropping funnel under ice-water bath conditions, while maintaining a stirring speed of 180 rpm. The mixture was stirred at 0 °C for 72 hours, resulting in a viscous, pale yellow solution. This solution was slowly poured into an ethanol-water solution to obtain the polymer. The polymer was cut into small pieces and washed with 1 M K₂CO₃ solution at 50 °C with stirring for 12 hours. Finally, the polymer was washed repeatedly with deionized water until neutral and dried in an oven at 80 °C to obtain the polymer shown in Formula A1.

[0032] Step 2: In a round-bottom flask, dissolve the polymer (2g) shown in Formula A1 and potassium carbonate (0.2g) in 20mL of DMF. Add 2mL of iodomethane to the solution and stir under light for 24h. Pour the resulting solution into ethyl acetate solution, filter out the white precipitate, wash it several times with deionized water until it is neutral, and then dry it in a vacuum oven at 60-80℃ to obtain the quaternized polymer shown in Formula A2.

[0033] Step 3: Dissolve 1g of the quaternized polymer as shown in Formula A2 in 20mL of DMF, and stir at 50-60℃ until clear and transparent. Filter the solution through a 0.45μm polytetrafluoroethylene (PTFE) filter, cast the solution onto a clean glass plate, and dry in an oven at 80℃ to obtain I. - Type I film; the obtained I - The membrane was peeled off and immersed in a 1M NaOH solution for ion exchange to obtain OH-. - Anion exchange membranes in the form of polystyrene-4-methylenepiperidine homopolymers as shown in Formula A3. - Type of anion exchange membrane.

[0034] Example 2 The OH of the SEBS-4-vinylpiperidine homopolymer shown in Formula B3 - Taking a type of anion exchange membrane as an example, this invention introduces a method for preparing an anion exchange membrane, the synthetic reaction route of which is as follows: ; An anion exchange membrane (SEBS-4-vinylpiperidine homopolymer OH) - The preparation method of the anion exchange membrane includes the following steps: Step 1: In a three-necked flask, SEBS (0.0547 mol, 4 g) and 4-vinylpiperidine hydrochloride (16.4 mmol, 2.42 g) were dissolved in 60 mL of dichloromethane. The system was slowly stirred using a PTFE two-blade stirrer and a mechanical stirrer to ensure uniform mixing of the reactants and dichloromethane solvent. Subsequently, under ice-water bath conditions, trifluoromethanesulfonic acid (0.3282 mol, 28.79 mL) was slowly added to the system using a constant-pressure dropping funnel, while maintaining a stirring speed of 180 rpm. The mixture was stirred at 0 °C for 72 hours, resulting in a viscous, pale yellow solution. This solution was slowly poured into an ethanol-water solution to obtain the polymer. The polymer was cut into small pieces and washed with 1 M K₂CO₃ solution at 50 °C with stirring for 12 hours. Finally, the polymer was washed repeatedly with deionized water until neutral and dried in an oven at 80 °C to obtain the polymer shown in Formula B1.

[0035] Step 2: In a round-bottom flask, dissolve the polymer (2g) as shown in Formula B1 and potassium carbonate (0.2g) in 20mL of DMF. Add 2mL of iodomethane to the solution and stir under light for 24h. Pour the resulting solution into ethyl acetate solution, filter out the white precipitate, wash it several times with deionized water until it is neutral, and then dry it in a vacuum oven at 60-80℃ to obtain the quaternized polymer as shown in Formula B2.

[0036] Step 3: Dissolve 1g of the quaternized polymer shown in Formula B2 in 20mL of DMF, and stir at 50-60℃ until clear and transparent. Filter the solution through a 0.45μm polytetrafluoroethylene (PTFE) filter, cast the solution onto a clean glass plate, and dry in an oven at 80℃ to obtain I. - Type I film; the obtained I - The membrane was peeled off and immersed in a 1M NaOH solution for ion exchange to obtain OH-. - The form of anion exchange membrane, namely the OH group of SEBS-4-vinylpiperidine homopolymer as shown in Formula B3. - Type of anion exchange membrane.

[0037] Example 3 The OH of the SEBS-3-methylenequinine homopolymer shown in formula C3 - Taking a type of anion exchange membrane as an example, this invention introduces a method for preparing an anion exchange membrane, the synthetic reaction route of which is as follows: ; An anion exchange membrane (SEBS-3-methylenequinine homopolymer OH) - The preparation method of the anion exchange membrane includes the following steps: Step 1: In a three-necked flask, SEBS (0.0547 mol, 4 g) and 3-methylenequinine hydrochloride (16.4 mmol, 2.95 g) were dissolved in 60 mL of dichloromethane. The system was slowly stirred using a PTFE two-blade stirrer and a mechanical stirrer to ensure uniform mixing of the reactants and dichloromethane solvent. Subsequently, under ice-water bath conditions, trifluoromethanesulfonic acid (0.3282 mol, 28.79 mL) was slowly added to the system using a constant-pressure dropping funnel, while maintaining a stirring speed of 180 rpm. The mixture was stirred at 0 °C for 72 hours, resulting in a viscous, pale yellow solution. This solution was slowly poured into an ethanol-water solution to obtain the polymer. The polymer was cut into small pieces and washed with 1 M K₂CO₃ solution at 50 °C with stirring for 12 hours. Finally, the polymer was washed repeatedly with deionized water until neutral and dried in an oven at 80 °C to obtain the polymer shown in formula C1.

[0038] Step 2: In a round-bottom flask, dissolve the polymer (2g) and potassium carbonate (0.2g) shown in formula C1 in 20mL of DMF, add 2mL of iodomethane to the solution, stir and react in the dark for 24h, pour the resulting solution into ethyl acetate solution, filter out the white precipitate, wash it several times with deionized water until it is neutral, and then dry it in a vacuum oven at 60-80℃ to obtain the quaternized polymer shown in formula C2.

[0039] Step 3: Dissolve 1g of the quaternized polymer shown in formula C2 in 20mL of DMF, and stir at 50-60℃ until clear and transparent. Filter the solution through a 0.45μm polytetrafluoroethylene (PTFE) filter, cast the solution onto a clean glass plate, and dry in an oven at 80℃ to obtain I. - Type I film; the obtained I - The membrane was peeled off and immersed in a 1M NaOH solution for ion exchange to obtain OH-. - The form of anion exchange membrane, namely the OH group of SEBS-3-methylenequinine homopolymer shown in formula C3. - Type of anion exchange membrane.

[0040] Example 4 The OH of the ABS-3-vinyl-1-methylpiperidine homopolymer shown in Formula D3 - Taking a type of anion exchange membrane as an example, this invention introduces a method for preparing an anion exchange membrane, the synthetic reaction route of which is as follows: ; An anion exchange membrane (ABS-3-vinyl-1-methylpiperidine homopolymer OH) - The preparation method of the anion exchange membrane includes the following steps: Step 1: In a three-necked flask, ABS (0.0526 mol, 4 g) and 3-vinyl-1-methylpiperidine hydrochloride (15.7 mmol, 2.54 g) were dissolved in 60 mL of dichloromethane. The system was slowly stirred using a PTFE two-blade stirrer and a mechanical stirrer to ensure uniform mixing of the reactants and dichloromethane solvent. Subsequently, under ice-water bath conditions, trifluoromethanesulfonic acid (0.3156 mol, 27.70 mL) was slowly added to the system using a constant-pressure dropping funnel, maintaining a stirring speed of 180 rpm. The mixture was stirred at 0 °C for 72 hours, resulting in a viscous, pale yellow solution. This solution was slowly poured into an ethanol-water solution to obtain the polymer. The polymer was cut into small pieces and washed with 1 M K₂CO₃ solution at 50 °C with stirring for 12 hours. Finally, the polymer was washed repeatedly with deionized water until neutral and dried in an oven at 80 °C to obtain the polymer shown in Formula D1.

[0041] Step 2: In a round-bottom flask, dissolve the polymer (2g) shown in Formula D1 and potassium carbonate (0.2g) in 20mL of DMF. Add 2mL of iodomethane to the solution and stir under light for 24h. Pour the resulting solution into ethyl acetate solution, filter out the white precipitate, wash it several times with deionized water until it is neutral, and then dry it in a vacuum oven at 60-80℃ to obtain the quaternized polymer shown in Formula D2.

[0042] Step 3: Dissolve 1g of the quaternized polymer shown in formula D2 in 20mL of DMF, and stir at 50-60℃ until clear and transparent. Filter the solution through a 0.45μm polytetrafluoroethylene (PTFE) filter, cast the solution onto a clean glass plate, and dry in an oven at 80℃ to obtain I. - Type I film; the obtained I - The membrane was peeled off and immersed in a 1M NaOH solution for ion exchange to obtain OH-. - Anion exchange membranes in the form of ABS-3-vinyl-1-methylpiperidine homopolymer as shown in Formula D3. - Type of anion exchange membrane.

[0043] Example 5 The OH of ASA-3-methylenepiperidine polymer as shown in Formula E3 - Taking a type of anion exchange membrane as an example, this invention introduces a method for preparing an anion exchange membrane, the synthetic reaction route of which is as follows: ; An anion exchange membrane (ASA-3-methylenepiperidine polymer OH) - The preparation method of the anion exchange membrane includes the following steps: Step 1: In a three-necked flask, ASA (0.0381 mol, 4 g) and 3-methylenepiperidine hydrochloride (11.4 mmol, 1.52 g) were dissolved in 60 mL of dichloromethane. The system was slowly stirred using a PTFE two-blade stirrer and a mechanical stirrer to ensure uniform mixing of the reactants and dichloromethane solvent. Subsequently, under ice-water bath conditions, trifluoromethanesulfonic acid (0.2286 mol, 20.06 mL) was slowly added to the system using a constant-pressure dropping funnel, maintaining a stirring speed of 180 rpm. The mixture was stirred at 0 °C for 72 hours, resulting in a viscous, pale yellow solution. This solution was slowly poured into an ethanol-water solution to obtain the polymer. The polymer was cut into small pieces and washed with 1 M K₂CO₃ solution at 50 °C with stirring for 12 hours. Finally, the polymer was washed repeatedly with deionized water until neutral and dried in an oven at 80 °C to obtain the polymer shown in Formula E1.

[0044] Step 2: In a round-bottom flask, dissolve the polymer (2g) as shown in Formula E1 and potassium carbonate (0.2g) in 20mL of DMF. Add 2mL of iodomethane to the solution and stir under light for 24h. Pour the resulting solution into ethyl acetate solution, filter out the white precipitate, wash it several times with deionized water until it is neutral, and then dry it in a vacuum oven at 60-80℃ to obtain the quaternized polymer as shown in Formula E2.

[0045] Step 3: Dissolve 1g of the quaternized polymer as shown in Formula E2 in 20mL of DMF, and stir at 50-60℃ until clear and transparent. Filter the solution through a 0.45μm polytetrafluoroethylene (PTFE) filter, cast the solution onto a clean glass plate, and dry in an oven at 80℃ to obtain I. - Type I film; the obtained I - The membrane was peeled off and immersed in a 1M NaOH solution for ion exchange to obtain OH-. - The form of anion exchange membrane, namely the OH group of ASA-3-methylenepiperidine polymer as shown in Formula E3. - Type of anion exchange membrane.

[0046] Comparative Example 1 The OH of SEBS-methylpiperidine polymer as shown in Formula F3 - Taking a type of anion exchange membrane as an example, this invention introduces a method for preparing an anion exchange membrane, the synthetic reaction route of which is as follows: ; An anion exchange membrane (SEBS-methylpiperidine polymer OH) - The preparation method of the anion exchange membrane includes the following steps: Step 1: In a three-necked flask, dissolve SEBS (0.0547 mol, 4 g) in 60 mL of chloroform. Use a PTFE two-blade stirrer and a mechanical stirrer to slowly stir the system until the reactants and solvent chloroform are thoroughly mixed. Then, using a constant-pressure dropping funnel, slowly add 7.2 mL of 1,4-dichloromethoxybutane and 0.8 mL of anhydrous tin tetrachloride to the system, maintaining a stirring speed of 180 rpm. Stir at 50 °C for 4 hours. Pour the reaction solution into methanol, and a light purple flocculent precipitate will form. Wash with tetrahydrofuran 3-4 times to obtain a white blocky solid. Dry the solid in a vacuum oven at 60-80 °C to obtain the compound shown in Formula F1.

[0047] Step 2: In a round-bottom flask, dissolve 2 g of a white solid (the compound shown in Formula F1) and 0.2 g of potassium carbonate in 20 mL of DMF. Add 4 mL of methylpiperidine to the solution and stir under light for 24 h. Pour the resulting solution into an ethyl acetate solution. Filter out the white precipitate and wash it several times with deionized water until it is neutral. Then, dry it in a vacuum oven at 60-80 °C to obtain the quaternized polymer shown in Formula F2.

[0048] Step 3: Dissolve 1g of the quaternized polymer as shown in Formula F2 in 20mL of DMF, and stir at 50-60℃ until clear and transparent. Filter the solution through a 0.45μm polytetrafluoroethylene (PTFE) filter, cast the solution onto a clean glass plate, and dry in an oven at 80℃ to obtain I. - Type I film; the obtained I - The membrane was peeled off and immersed in a 1M NaOH solution for ion exchange to obtain OH-. - The form of anion exchange membrane, namely the SEBS-methylpiperidine polymer shown in Formula F3, OH - Type of anion exchange membrane.

[0049] Example 1 OH of the polystyrene-4-methylenepiperidine homopolymer shown in Formula A3 in Example 1 - The proton NMR spectrum of the type anion exchange membrane was performed, and the results are shown in the figure. Figure 1 ; from Figure 1 It can be seen that the characteristic peak of H in the benzene ring of polystyrene appears at 6.43-6.95 ppm, the characteristic peak of methylene in 4-methylenepiperidine appears at 1.37-1.67 ppm, and the characteristic peak of methyl appears at 2.76 ppm.

[0050] Example 2 OH of each embodiment - The ion conductivity and tensile strength of the anion exchange membrane were tested, and the results are shown in Table 1. Test method for ionic conductivity: In the experiment, the membrane was cut into pieces of 4cm×1cm, placed in a polytetrafluoroethylene fixture, and tested at 30℃-80℃. Finally, the ionic conductivity σ of the sample was calculated according to the formula. σ = L / (wdR); where L is the length of the interelectrode membrane (cm), w is the width of the membrane (cm), d is the thickness of the membrane (cm), and R is the measured resistance of the membrane (Ω). Tensile strength: The instrument used in the experiment was a tensile testing machine; the membrane was cut into rectangular strips of 1 cm × 5 cm. Before the tensile test, the width of the narrowest part of the membrane and the thickness of the membrane were measured. During the tensile test, the two ends of the membrane were clamped and the membrane was pulled outward at a fixed speed. The stress-strain curve of the membrane was recorded. By recording the maximum force and the longest tensile length at which the membrane breaks, the tensile strength of the membrane can be calculated.

[0051] Table 1: .

[0052] Example 3 In 1M KOH solution, the OH groups in Example 2 and Comparative Example 1 were measured. - The conductivity of the type-3 anion exchange membrane as a function of time was shown in the figure, with the test temperature at 80℃. Figure 2 ; from Figure 2 It can be seen that in 1M KOH solution, the conductivity of the anion exchange membranes prepared in Example 2 and Comparative Example 1 both decreased with time, but the anion exchange membrane prepared in Example 2 had better alkali resistance than that in Comparative Example 1.

[0053] The embodiments described above are merely preferred embodiments of the present invention, and not an exhaustive list of all possible implementations of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A polymer for preparing highly alkali-stable anion exchange membranes, characterized in that, It includes a polystyrene backbone or a polystyrene-containing block copolymer backbone, and a nitrogen heterocyclic monomer, wherein the nitrogen heterocyclic monomer is bonded to the phenyl para-position of the polystyrene backbone or the polystyrene-containing block copolymer backbone via a methylene bond.

2. The polymer for preparing a highly alkali-stable anion exchange membrane according to claim 1, characterized in that, The polystyrene-containing block copolymer includes any one of styrene-butadiene-styrene block copolymer, acrylonitrile-butadiene-styrene block copolymer, styrene-acrylonitrile block copolymer, styrene-methyl methacrylate block copolymer, and acrylonitrile-styrene-acrylate block copolymer.

3. The polymer for preparing a highly alkali-stable anion exchange membrane according to claim 1, characterized in that, The structural formula is shown in any one of equations 1-6: ； In Equations 1-6, x, y, and z represent the molar percentage of the corresponding blocks in the polymer; x + y + z = 100%, 20% ≤ x ≤ 100%, 0% ≤ y ≤ 80%, and 0% ≤ z ≤ 60%. In Equations 1-6, R is independently selected from... , , , , , , , , , , Any one of them.

4. The method for preparing the polymer according to any one of claims 1-3, characterized in that, Includes the following steps: Under ice-water bath conditions, the main-chain polymer and unsaturated nitrogen heterocyclic monomers are dissolved in a first solvent, then stirred, and trifluoromethanesulfonic acid is added dropwise while stirring continuously for at least 72 hours to obtain a viscous solution; then the viscous solution is poured into a second solvent to obtain a solid polymer; the excess acid remaining in the solid polymer is washed with a first alkaline solution, and then washed repeatedly with deionized water until neutral, and dried in a vacuum oven to obtain the polymer according to any one of claims 1-4; wherein the main-chain polymer is polystyrene or a block copolymer containing polystyrene.

5. The polymer for preparing a highly alkali-stable anion exchange membrane according to claim 4, characterized in that, The unsaturated nitrogen heterocyclic monomer includes any one of 4-vinylpiperidine hydrochloride, 4-vinylpiperidine hydrochloride, 3-vinylpiperidine hydrochloride, 4-methylenepiperidine hydrochloride, 1,2,3,6,tetrahydropyridine hydrochloride, 3-vinylpiperidine hydrochloride, 2-vinylpiperidine hydrochloride, 3-methylenepiperidine hydrochloride, N-vinylpyrrolidone hydrochloride, 2-vinylpiperidine hydrochloride, and 3-methylene-1-azabicyclo[2.2.2]octane hydrochloride.

6. The preparation method according to claim 4, characterized in that, The molar ratio of the main-chain polymer to the unsaturated nitrogen heterocyclic monomer is 1:0.3-0.5; The molar ratio of the unsaturated nitrogen-containing heterocyclic monomer to trifluoromethanesulfonic acid is 1:8-20; The first solvent is one or more of dichloromethane solution, trichloromethane, and 1,2-dichloroethane; The second solvent is one or more of water, ethyl acetate, methanol, and ethanol; The first alkaline solution is any one of K2CO3 solution, KOH solution, NaOH solution, and NaHCO3 solution; The concentration of the first alkaline solution is 0.5-2.0M.

7. A highly alkali-stable anion exchange membrane, characterized in that, The structure includes a polystyrene backbone or a polystyrene-containing block copolymer backbone, and a nitrogen-containing heterocyclic cationic functional group on the polystyrene backbone or the polystyrene-containing block copolymer backbone, wherein the nitrogen-containing heterocyclic cationic functional group is selected from... , , , , , , , , , , Any one of them.

8. A method for preparing a high-alkali-stability anion exchange membrane as described in claim 7, characterized in that, Prepared from the polymer according to any one of claims 1-4, the preparation method includes the following steps: Step a: Dissolve the polymer according to any one of claims 1-4 in a third solvent, then add K2CO3 and iodomethane, stir at 40-50°C for at least 48 hours to obtain a viscous solution, then pour the viscous solution into a fourth solvent to precipitate a white precipitate, then filter, collect the white precipitate, wash with deionized water, and dry in a vacuum oven to obtain a quaternized polymer; Step b: Dissolve the obtained quaternized polymer in the fifth solvent, stir at 50-60℃, filter through a 0.25-0.45μm polytetrafluoroethylene (PTFE) filter, cast the solution onto a clean glass plate, and dry in an oven at 80-120℃ to obtain I. - Type film; The obtained I - The membrane is peeled off and immersed in anion exchange solution for ion exchange to obtain a highly alkaline stable anion exchange membrane.

9. The method for preparing a high-alkali-stability anion exchange membrane according to claim 8, characterized in that, In step a, the mass-volume ratio of the polymer and the third solvent is 1 g:(6-10) mL; The third solvent is one or more of N,N-dimethylformamide, N,N-diethylformamide, N-methylpyrrolidone, and toluene; The fourth solvent is ethyl acetate, methanol, ethanol, acetone, or diethyl ether; In step b, the fifth solvent is one or more of N,N-dimethylformamide, N,N-diethylformamide, N-methylpyrrolidone, and toluene; The mass-volume ratio of the quaternized polymer and the fifth solvent is 1 g:(15-25) mL; Anion exchange solutions include one or more of NaOH, KOH, NaCl, KCl, NaBr, KBr, Na2SO4, and Na2CO3; The concentration of the anion exchange solution is 0.5-2.0M.

10. The application of the high-alkali-stability anion exchange membrane as described in claim 7 in anion exchange membrane water electrolysis for hydrogen production.

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