A branched polyarylpiperidine anion exchange membrane, its preparation method and application

Abstract

This invention belongs to the field of new materials technology and discloses a branched polyarylpiperidine anion exchange membrane, its preparation method, and its applications. This invention provides a branched polyarylpiperidine polymer and anion exchange membrane that possess both high conductivity and alkali stability. The anion exchange membrane of this invention uses p-terphenyl as the main polymer chain structure, and simultaneously introduces a hydrophilic phenyl-containing monomer (octaphenylPOSS, octaphenylcyclotetrasiloxane) with a three-dimensional spatial structure into the polymer structure. This type of monomer has a three-dimensional spatial structure and rigid hydrophilic characteristics, which gives the polymer structure a larger free volume, establishing a smoother ion transport channel, thereby improving the electrochemical performance of the membrane. It has good application prospects in anion exchange membrane water electrolysis. The prepared anion exchange membrane has high conductivity and alkali stability and can be used in equipment such as water electrolyzers.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology, and relates to anion exchange membranes, particularly a branched polyarylpiperidine anion exchange membrane, its preparation method, and its application. Background Technology

[0002] With societal development, human demand for energy is increasing daily, and the non-renewable nature of fossil fuels is driving the exploration of green energy. Hydrogen energy is an excellent alternative energy source and can be produced through various methods. Among current hydrogen production technologies, combining renewable energy with water electrolysis, and storing and converting hydrogen to achieve peak shaving in time and space, is a truly effective method. With increasingly in-depth research into hydrogen energy, water electrolysis technology has also developed rapidly.

[0003] Water electrolysis technology is divided into proton exchange membrane (PEM) water electrolysis, alkaline water electrolysis, and anion exchange membrane (EEM) water electrolysis. Proton exchange membrane electrolysis requires a precious metal catalyst under acidic conditions, resulting in high costs. Alkaline water electrolysis has low hydrogen production efficiency and low gas purity, requiring further purification. Anion exchange membrane electrolysis does not require a precious metal catalyst and produces high gas purity. As a key component of anion exchange membrane water electrolyzers, the anion exchange membrane has received widespread attention and extensive research in recent years.

[0004] However, current anion exchange membranes suffer from low conductivity and poor stability, which limits their large-scale application. Therefore, developing anion exchange membranes with high conductivity and stability has become a current research focus. Anion exchange membranes are mainly composed of a polymer backbone and cationic groups. Membrane materials based on backbones such as polysulfone, polyetheretherketone, and polyphenylene ether have been developed. However, studies have shown that under alkaline conditions, the presence of ether bonds in the backbone leads to membrane degradation. Ether-free structures have become a new research direction. Polyarylpiperidine, as a novel ether-free structure, exhibits good dimensional stability and rigidity. Furthermore, numerous studies have demonstrated its excellent alkaline stability. However, the linear structure of polyarylpiperidine hinders the formation of ion transport channels, resulting in low conductivity in backbone-type polyarylpiperidine anion exchange membranes. Therefore, developing a polyarylpiperidine anion exchange membrane that combines high conductivity and high stability has become an urgent problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a branched polyarylpiperidine anion exchange membrane, its preparation method, and its application.

[0006] The technical solution adopted by this invention to solve its technical problem is: A branched polyarylpiperidine anion exchange membrane, the structural formula of which is as follows: ; Wherein, Ar1 is a three-dimensional spatial structure monomer, and Ar2 is a phenyl monomer; x is the number of Ar1 units in the anion exchange membrane polymer unit, and x is an integer greater than zero; y represents the number of Ar2 atoms in the anion exchange membrane polymer unit, and y is a positive integer; y = y1 + y2 + y3 + y4 + y5 + y6 + y7 + y8, y:x = 20 - 200, x and y 1-8 All are within 10 million; y1, y2, y3, y4, y5, y6, y7, and y8 are the numbers of phenyl monomers attached to different benzene rings of Ar1, and are all integers greater than zero.

[0007] Furthermore, the three-dimensional spatial structure monomer is octaphenyl POSS, with the chemical name 1,3,5,7,9,11,13,15-octaphenylpentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane, CAS number 5256-79-1, and its structural formula is: ; The phenyl monomer has one of the following structural formulas: .

[0008] A method for preparing the branched polyarylpiperidine anion exchange membrane as described above includes the following steps: (1) Mix the three-dimensional spatial structure monomer, phenyl monomer, N-methyl-4-piperidinone and solvent, add acid catalyst under -30℃~5℃ conditions, stir and react, add NaOH to precipitate branched polyaryl polymer; (2) The branched polyaryl polymer obtained in step (1) is mixed with a first polar solvent to obtain a polymer solution; an alkaline substance is added to the polymer solution, followed by the addition of iodoalkane / bromoalkane to carry out a quaternization reaction, and ethyl acetate is added to precipitate the polyelectrolyte resin. (3) Mix the polyelectrolyte resin obtained in step (2) with a polar solvent to obtain a film-forming liquid; cast or cast the film-forming liquid onto a substrate and dry it to obtain a branched polyarylpiperidine anion exchange membrane.

[0009] Further, in step (1), the acid catalyst is at least one of trifluoromethanesulfonic acid, trifluoroacetic acid, acetic acid, trichloroacetic acid, methanesulfonic acid, pentafluoropropionic acid, heptafluorobutyric acid and perfluorosulfonic acid resin; Alternatively, the stirring reaction time in step (1) is 1 to 72 hours, and the stirring reaction temperature is -10 to 10°C. Alternatively, the solvent in step (1) may be dichloromethane; Alternatively, in step (1), the molar ratio of the three-dimensional spatial structure monomer: phenyl monomer: N-methyl-4-piperidinone: solvent: acid catalyst is 5~50:1:1.2~1.6:6.24~12.48:11.53~14.99.

[0010] Further, in step (2), the first polar solvent is at least one of tetrahydrofuran, acetonitrile, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide; Alternatively, in step (2), the mass ratio of branched polyaryl polymer: alkaline substance: iodoalkanes / bromoalkanes is 1:(0.5~8):(0.5~8). Alternatively, the quaternization reaction time in step (2) is 12~72h, and the quaternization reaction temperature is -10~50℃.

[0011] Furthermore, in step (3), the drying temperature is 5~200℃ and the drying time is 0.1~72h; Alternatively, the polar solvent in step (3) is dimethyl sulfoxide (DMSO); Alternatively, in step (3), the mass ratio of polyelectrolyte resin to polar solvent is 1:20; Alternatively, the substrate in step (3) can be a glass plate or a polytetrafluoroethylene plate.

[0012] Furthermore, the specific steps are as follows: Preparation of S1 branched polyarylpiperidine polymer: terphenyl, N-methyl-4-piperidinone and a three-dimensional monomer were added to dichloromethane solvent and stirred with a mechanical stirrer for 30 min under ice-water bath conditions. Then, trifluoroacetic acid and trifluoromethanesulfonic acid were added dropwise. After reacting for 6-8 h, the resulting viscous solution was poured into a 5 mol / L NaOH solution, and a white to pale yellow polymer precipitated. The polymer was crushed, washed repeatedly with deionized water until neutral, and finally dried to obtain the branched polyarylene piperidine polymer P-PTPa-x. In step S1, the molar ratio of the three-dimensional spatial structure monomer to p-terphenyl is (0.5~2):(99.5~98), the molar ratio of p-terphenyl to N-methyl-4-piperidinone is 1:(1.3~1.5), the molar ratio of trifluoroacetic acid to N-methyl-4-piperidinone is 1:(1.1~1.2), the molar ratio of trifluoromethanesulfonic acid to N-methyl-4-piperidinone is (9.3~10):1, and 11~12 mmol of N-methyl-4-piperidinone is added for every 5 mL of dichloromethane. S2 OH - Preparation of type-3 anion exchange membranes: 1) Branched polyarylpiperidine polymer P-PTPa-x was added to dimethyl sulfoxide and stirred at room temperature for 30 min. Then K2CO3 was added and stirred at room temperature for 10 min. Then CH3I was added and the mixture was stirred in the dark at room temperature for 24-48 h. The resulting yellow viscous solution was added to ethyl acetate, and a white precipitate was obtained. The precipitate was filtered, washed three times with deionized water, and dried at 80 °C for 12 h to obtain quaternized polyarylpiperidine polymer P-PTPb-x (I - ); Wherein, the solid-liquid ratio of P-PTPa-x and CH3I is 1:1 (g:mL), the mass ratio of P-PTPa-x and K2CO3 is 1:1, the solid-liquid ratio of P-PTPa-x and dimethyl sulfoxide is 1:30 (g:mL), and the solid-liquid ratio of P-PTPa-x and ethyl acetate is 1:200 (g:mL). 2) P-PTPb-x (I - The solution was ultrasonically dissolved in dimethyl sulfoxide, filtered using a 0.8 μm polytetrafluoroethylene (PTFE) filter, ultrasonically defoamed and allowed to stand, then dropped onto a glass plate and dried at 80 °C for 5 h to obtain an I- form anion exchange membrane with a thickness of 60~70 μm. Among them, the P-PTPb-x (I - The solid-liquid ratio of dimethyl sulfoxide (DMSO) to dimethyl sulfoxide (DMSO) is 1:(14~16) g:mL. 3) Will I - The anion exchange membrane in this form was peeled off from the glass plate, immersed in a 1 mol / L NaOH solution for 48 hours, and then washed with deionized water to obtain OH⁻. - The anion exchange membrane is a branched polyarylpiperidine anion exchange membrane; subsequently, the membrane is stored by immersing it in degassed deionized water.

[0013] Furthermore, in step S2, OH - The structural formula of the type anion exchange membrane is as follows: .

[0014] The application of the branched polyarylpiperidine anion exchange membrane as described above in anion exchange membrane water electrolysis.

[0015] The application of the branched polyarylpiperidine anion exchange membrane as described above in anion exchange membrane alkaline water electrolyzers.

[0016] The advantages and positive effects of this invention are as follows: 1. This invention provides a branched polyarylpiperidine polymer and anion exchange membrane that possess both high conductivity and alkali stability. The anion exchange membrane of this invention uses p-terphenyl as the main polymer chain structure, and simultaneously introduces a hydrophilic phenyl-containing monomer (octaphenylPOSS, octaphenylcyclotetrasiloxane) with a three-dimensional spatial structure into the polymer structure. This type of monomer has a three-dimensional spatial structure and rigid hydrophilic characteristics, resulting in a larger free volume in the polymer structure and establishing smoother ion transport channels, thereby improving the electrochemical performance of the membrane. It shows good application prospects in anion exchange membrane water electrolysis. The prepared anion exchange membrane has high conductivity and alkali stability and can be used in equipment such as water electrolyzers.

[0017] 2. The preparation process of the exchange membrane of the present invention is simple. It is directly polymerized through a superacid catalytic reaction. The synthesis steps are relatively simple. Moreover, the main chain of the anion exchange membrane of the present invention does not contain ether bonds, which ensures its alkaline stability.

[0018] 3. The membrane prepared by this invention has high ionic conductivity. The unbranched main-chain anion exchange membrane prepared in Comparative Example 1 has a conductivity of 98.35 mS / cm at 80℃. However, after introducing a three-dimensional spatial structure monomer in this invention, a larger free volume is formed, which reduces the ion transport resistance. The anion exchange membrane P-PTPb-2% prepared by this invention has a conductivity of 156.81 mS / cm at 80℃. The conductivity performance of the membrane is greatly improved. Attached Figure Description

[0019] Figure 1 The nuclear magnetic resonance hydrogen spectrum of the anion exchange membrane prepared in Example 1 of this invention ( 1 H-NMR); Figure 2 The nuclear magnetic resonance hydrogen spectrum of the anion exchange membrane prepared in Comparative Example 1 of this invention is shown below. 1 H-NMR); Figure 3 This is a comparison chart of the conductivity of the anion exchange membranes described in Examples 1, 2, 3 and Comparative Example 1 of this invention at 80°C. Detailed Implementation

[0020] The present invention will be further described below with reference to the embodiments. The following embodiments are descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0021] The various experimental operations involved in the specific embodiments are all conventional techniques in the field. For parts not specifically annotated in this document, those skilled in the art can refer to various commonly used reference books, scientific and technological documents or related instructions and manuals prior to the filing date of this invention to carry out the operations.

[0022] A branched polyarylpiperidine anion exchange membrane, the structural formula of which is as follows: ; Wherein, Ar1 is a three-dimensional spatial structure monomer, and Ar2 is a phenyl monomer; x is the number of Ar1 units in the anion exchange membrane polymer unit, and x is an integer greater than zero; y represents the number of Ar2 atoms in the anion exchange membrane polymer unit, and y is a positive integer; y = y1 + y2 + y3 + y4 + y5 + y6 + y7 + y8, y:x = 20 - 200, x and y 1-8 All are within 10 million; y1, y2, y3, y4, y5, y6, y7, and y8 are the numbers of phenyl monomers attached to different benzene rings of Ar1, and are all integers greater than zero.

[0023] Furthermore, the three-dimensional spatial structure monomer is octaphenyl POSS, with the chemical name 1,3,5,7,9,11,13,15-octaphenylpentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane, CAS number 5256-79-1, and its structural formula is: ; The phenyl monomer has one of the following structural formulas: .

[0024] A method for preparing the branched polyarylpiperidine anion exchange membrane as described above includes the following steps: (1) Mix the three-dimensional spatial structure monomer, phenyl monomer, N-methyl-4-piperidinone and solvent, add acid catalyst under -30℃~5℃ conditions, stir and react, add NaOH to precipitate branched polyaryl polymer; (2) The branched polyaryl polymer obtained in step (1) is mixed with a first polar solvent to obtain a polymer solution; an alkaline substance is added to the polymer solution, followed by the addition of iodoalkane / bromoalkane to carry out a quaternization reaction, and ethyl acetate is added to precipitate the polyelectrolyte resin. (3) Mix the polyelectrolyte resin obtained in step (2) with a polar solvent to obtain a film-forming liquid; cast or cast the film-forming liquid onto a substrate and dry it to obtain a branched polyarylpiperidine anion exchange membrane.

[0025] Further, in step (1), the acid catalyst is at least one of trifluoromethanesulfonic acid, trifluoroacetic acid, acetic acid, trichloroacetic acid, methanesulfonic acid, pentafluoropropionic acid, heptafluorobutyric acid and perfluorosulfonic acid resin; Alternatively, the stirring reaction time in step (1) is 1 to 72 hours, and the stirring reaction temperature is -10 to 10°C. Alternatively, the solvent in step (1) may be dichloromethane; Alternatively, in step (1), the molar ratio of the three-dimensional spatial structure monomer: phenyl monomer: N-methyl-4-piperidinone: solvent: acid catalyst is 5~50:1:1.2~1.6:6.24~12.48:11.53~14.99.

[0026] Further, in step (2), the first polar solvent is at least one of tetrahydrofuran, acetonitrile, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide; Alternatively, in step (2), the mass ratio of branched polyaryl polymer: alkaline substance: iodoalkanes / bromoalkanes is 1:(0.5~8):(0.5~8). Alternatively, the quaternization reaction time in step (2) is 12~72h, and the quaternization reaction temperature is -10~50℃.

[0027] Furthermore, in step (3), the drying temperature is 5~200℃ and the drying time is 0.1~72h; Alternatively, the polar solvent in step (3) is dimethyl sulfoxide (DMSO); Alternatively, in step (3), the mass ratio of polyelectrolyte resin to polar solvent is 1:20; Alternatively, the substrate in step (3) can be a glass plate or a polytetrafluoroethylene plate.

[0028] Furthermore, the specific steps are as follows: Preparation of S1 branched polyarylpiperidine polymer: terphenyl, N-methyl-4-piperidinone and a three-dimensional monomer were added to dichloromethane solvent and stirred with a mechanical stirrer for 30 min under ice-water bath conditions. Then, trifluoroacetic acid and trifluoromethanesulfonic acid were added dropwise. After reacting for 6-8 h, the resulting viscous solution was poured into a 5 mol / L NaOH solution, and a white to pale yellow polymer precipitated. The polymer was crushed, washed repeatedly with deionized water until neutral, and finally dried to obtain the branched polyarylene piperidine polymer P-PTPa-x. In step S1, the molar ratio of the three-dimensional spatial structure monomer to p-terphenyl is (0.5~2):(99.5~98), the molar ratio of p-terphenyl to N-methyl-4-piperidinone is 1:(1.3~1.5), the molar ratio of trifluoroacetic acid to N-methyl-4-piperidinone is 1:(1.1~1.2), the molar ratio of trifluoromethanesulfonic acid to N-methyl-4-piperidinone is (9.3~10):1, and 11~12 mmol of N-methyl-4-piperidinone is added for every 5 mL of dichloromethane. S2 OH - Preparation of type-3 anion exchange membranes: 1) Branched polyarylpiperidine polymer P-PTPa-x was added to dimethyl sulfoxide and stirred at room temperature for 30 min. Then K2CO3 was added and stirred at room temperature for 10 min. Then CH3I was added and the mixture was stirred in the dark at room temperature for 24-48 h. The resulting yellow viscous solution was added to ethyl acetate, and a white precipitate was obtained. The precipitate was filtered, washed three times with deionized water, and dried at 80 °C for 12 h to obtain quaternized polyarylpiperidine polymer P-PTPb-x (I - ); Wherein, the solid-liquid ratio of P-PTPa-x and CH3I is 1:1 (g:mL), the mass ratio of P-PTPa-x and K2CO3 is 1:1, the solid-liquid ratio of P-PTPa-x and dimethyl sulfoxide is 1:30 (g:mL), and the solid-liquid ratio of P-PTPa-x and ethyl acetate is 1:200 (g:mL). 2) P-PTPb-x (I - The solution was ultrasonically dissolved in dimethyl sulfoxide, filtered using a 0.8 μm polytetrafluoroethylene (PTFE) filter, ultrasonically defoamed and allowed to stand, then dropped onto a glass plate and dried at 80 °C for 5 h to obtain an I- form anion exchange membrane with a thickness of 60~70 μm. Among them, the P-PTPb-x (I - The solid-liquid ratio of dimethyl sulfoxide (DMSO) to dimethyl sulfoxide (DMSO) is 1:(14~16) g:mL. 3) Will I - The anion exchange membrane in this form was peeled off from the glass plate, immersed in a 1 mol / L NaOH solution for 48 hours, and then washed with deionized water to obtain OH⁻. - The anion exchange membrane is a branched polyarylpiperidine anion exchange membrane; subsequently, the membrane is stored by immersing it in degassed deionized water.

[0029] Furthermore, in step S2, OH - The structural formula of the type anion exchange membrane is as follows: .

[0030] The application of the branched polyarylpiperidine anion exchange membrane as described above in anion exchange membrane water electrolysis.

[0031] The application of the branched polyarylpiperidine anion exchange membrane as described above in anion exchange membrane alkaline water electrolyzers.

[0032] Specifically, the relevant preparation and testing methods are as follows: This invention prepares a branched anion exchange membrane by polymerizing p-terphenyl, N-methyl-4-piperidinone, and a three-dimensional monomer under superacid catalysis. The introduction of the three-dimensional monomer increases the free volume within the membrane, creating more unobstructed ion transport channels and thus improving the membrane's ionic conductivity. For comparison, a linear anion exchange membrane (P-PTPb-0%) without the branching agent was prepared using the same method. The application of the branched anion exchange membrane in water electrolysis was evaluated by testing its conductivity.

[0033] Example 1 This embodiment provides a branched polyarylpiperidine anion exchange membrane, which is prepared by the following method.

[0034] (1) 3.918 g (17.0128 mmol), octaphenyl POSS (0.359 g, 0.3472 mmol), and N-methyl-4-piperidinone (2.75 g, 24.3040 mmol) were added sequentially to a 100 mL three-necked flask, followed by 10 mL of dichloromethane. The mixture was mechanically stirred for 30 min under ice-water bath conditions to obtain a pale yellow mixed solution. Then, 2 mL of trifluoroacetic acid (26.9360 mmol) and 20 mL of trifluoromethanesulfonic acid (227.4846 mmol) were added dropwise to the above mixed solution. After the addition was complete, the mixture was stirred for 7 h. As the reaction proceeded, the color of the solution gradually changed from pale yellow to dark blue and became more viscous. After the reaction was complete, 100 mL of 5 mol / L NaOH was poured dropwise into the three-necked flask, and the thin film on the surface of the solution was punctured to promote complete reaction. After puncturing and letting stand for 2 hours, a fibrous white precipitate was obtained; (2) The obtained precipitate was soaked in deionized water, washed until neutral, and dried at 85°C for 12 h. This yielded P-PTPa-2%; (3) Weigh 2g of P-PTPa-2% and pour it into a 200mL beaker. Then add 60mL of dimethyl sulfoxide and stir at room temperature for 30min. Add 2g of K2CO3 and 2mL of CH3I and stir at room temperature in the dark for 48h to obtain a yellow viscous solution. Add 200mL of ethyl acetate dropwise to the solution, filter, wash three times with deionized water, and dry at 80℃ for 12h to obtain the quaternized polyarylene piperidine polymer (P-PTPb-2% (I - )); (4) P-PTPb-2% (I - (0.55g) was ultrasonically dissolved in dimethyl sulfoxide (8mL), filtered using a 0.8μm polytetrafluoroethylene (PTFE) filter, cast onto a glass plate, and dried in a drying oven at 80℃ for 5h to obtain I. - Anion exchange membrane in various forms; (5) Immerse the glass plate in deionized water, peel it off, and then soak it in 1M NaOH solution for 48 hours to complete the activation, obtaining anion exchange membrane in OH- form. For long-term storage, immerse the membrane in degassed deionized water. When using, soak it in 1M NaOH solution for 12 hours to complete the activation. Following the above steps, Example 1 yielded a branched anion exchange membrane (P-PTPb-2%). The 2% mentioned above represents the ratio of octaphenyl POSS to the total molar amount of p-terphenyl and octaphenyl POSS. like Figure 1 As shown, the polymer structure can be confirmed by hydrogen nuclear magnetic resonance spectroscopy. Figure 1 H 1 H 2 H 3 For the three equivalent hydrogens in terphenyl, H 4 H 5 The two equivalent hydrogens on the piperidine ring, H 6 H is the equivalent hydrogen of the methyl group on the piperidine ring. 7 H 8 The two equivalent hydrogen atoms on the octaphenyl POSS were used to confirm the synthesis of the following polymers: .

[0035] Measurements were performed using a Metrohm PGSTAT302N electrochemical workstation. Before testing, the average thickness of the membrane was measured using electrochemical impedance spectroscopy (EIS) at a frequency of 1 MHz to 0.1 Hz. An H-type electrolytic cell was used, and the testing temperature range was 30–80 °C. After the test is completed, the conductivity can be obtained according to the formula. б ; б=L / AR ,in L It is the distance between the electrodes (cm). A It is the effective contact area of ​​the membrane sample (cm²) 2 ), R It is the ohmic resistance (Ω) of the membrane sample; Test results show that, Figure 3As shown, at 80℃, the conductivity of the P-PTPb-2% membrane is 156.81 mS / cm, and the conductivity of the P-PTPb-0% membrane is 98.35 mS / cm, proving that the introduction of the branching agent significantly improves the conductivity and has good application prospects.

[0036] Example 2 All steps not mentioned in this embodiment are the same as in Example 1, except that the mass of octaphenyl POSS in step (1) is changed from 0.359g to 0.179g, and the mass of p-terphenyl is changed from 3.918g to 3.958g. In this embodiment, a branched polyarylpiperidine anion exchange membrane P-PTPb-1% was obtained, and the conductivity of the membrane was tested. The 1% mentioned above represents the ratio of octaphenyl POSS to the total molar amount of p-terphenyl and octaphenyl POSS. Test results show that, Figure 3 As shown, at 80℃, the conductivity of the P-PTPb-1% membrane is 128.45 mS / cm, while the conductivity of the comparative example 1P-PTPb-0% membrane is 98.35 mS / cm. This demonstrates that the introduction of the branching agent improves the conductivity and has good application prospects.

[0037] Example 3 All steps not mentioned in this embodiment are the same as in Example 1, except that the mass of octaphenyl POSS in step (1) is changed from 0.179g to 0.089g, and the mass of p-terphenyl is changed from 3.958g to 3.978g. In this embodiment, a branched polyarylpiperidine anion exchange membrane P-PTPb-0.5% was obtained, and the conductivity of the membrane was tested. The 0.5% mentioned above represents the ratio of octaphenyl POSS to the total molar amount of p-terphenyl and octaphenyl POSS. Test results show that, Figure 3 As shown, at 80℃, the conductivity of the P-PTPb-0.5% membrane was 112.76 mS / cm, while the conductivity of the comparative example 1P-PTPb-0% membrane was 98.35 mS / cm. This demonstrates that the introduction of the branching agent improved the conductivity and has good application prospects.

[0038] Comparative Example 1 To compare the performance of the branched anion exchange membranes obtained in Examples 1, 2, and 3, a linear anion exchange membrane without a branching agent was prepared by the following method: (1) 4.000 g (17.36 mmol) of terphenyl and 2.56 g (22.56 mmol) of N-methyl-4-piperidinone were added sequentially to a 100 mL three-necked flask, followed by 10 mL of dichloromethane. The mixture was mechanically stirred for 30 min under ice-water bath conditions to obtain a pale yellow mixed solution. Then, 2 mL of trifluoroacetic acid (26.9360 mmol) and 20 mL of trifluoromethanesulfonic acid (227.4846 mmol) were added dropwise to the above mixed solution. After the addition was complete, the mixture was stirred for 6 h. As the reaction proceeded, the color of the solution gradually changed from pale yellow to dark blue and became more viscous. After the reaction was complete, 100 mL of 5 mol / L NaOH was poured dropwise into the three-necked flask to puncture the thin film on the surface of the solution to promote a complete reaction. After puncturing, the mixture was allowed to stand for 2 h to obtain a fibrous white precipitate. (2) The obtained precipitate was soaked in deionized water, washed until neutral, and dried at 85°C for 12 hours. This yielded P-PTPa-0%; (3) Weigh 2g of P-PTPa-0% and pour it into a 200mL beaker. Then add 60mL of dimethyl sulfoxide and stir at room temperature for 30min. Add 2g of K2CO3 and 2mL of CH3I and stir at room temperature in the dark for 48h to obtain a yellow viscous solution. Add 200mL of ethyl acetate dropwise to the solution, filter, wash three times with deionized water, and dry at 80℃ for 12h to obtain the quaternized polyarylpiperidine polymer (P-PTPb-0% (I - )); (4) P-PTPb-0% (I - (0.55g) was ultrasonically dissolved in dimethyl sulfoxide (8mL), filtered using a 0.8μm polytetrafluoroethylene (PTFE) filter, cast onto a glass plate, and dried in a drying oven at 80℃ for 5h to obtain I. - Anion exchange membrane in various forms; (5) Immerse the glass plate in deionized water, peel it off, and then soak it in 1M NaOH solution for 48 hours to complete the activation, obtaining anion exchange membrane in OH- form. For long-term storage, immerse the membrane in degassed deionized water. When using, soak it in 1M NaOH solution for 12 hours to complete the activation. In Comparative Example 1, an unbranched polyarylpiperidine anion exchange membrane P-PTPb-0% was prepared, and the conductivity of the membrane was tested. like Figure 2 As shown, the 1H NMR spectrum can confirm the polymer structure. Figure 2 H 1 H 2 H 3 For the three equivalent hydrogens in terphenyl, H 4 H 5 The two equivalent hydrogens on the piperidine ring, H6 Using the equivalent hydrogen atom of the methyl group on the piperidine ring, confirm the synthesis of the following polymers; Test results show that at 80℃, the conductivity of the P-PTPb-0% membrane prepared in Comparative Example 1 is 98.35 mS / cm.

[0039] In summary, cationic groups and polymer backbones are the two main components of cation exchange membranes, and appropriate backbone design and selection of cationic groups are crucial to the performance of anion exchange membranes. Polyarylpiperidine, with its excellent alkali resistance, is a popular choice for the backbone of anion exchange membranes. Given its low conductivity, branching can induce significant microphase separation in the structure, increasing the membrane's free volume and thus creating more unobstructed ion transport channels, thereby improving the electrochemical performance of the anion exchange membrane.

[0040] Although embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations, and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the scope of the invention is not limited to the contents disclosed in the embodiments.

Claims

1. A branched polyarylpiperidine anion exchange membrane, characterized in that: The structural formula of the anion exchange membrane is as follows: ； Wherein, Ar1 is a three-dimensional spatial structure monomer, and Ar2 is a phenyl monomer; x is the number of Ar1 units in the anion exchange membrane polymer unit, and x is an integer greater than zero; y represents the number of Ar2 atoms in the anion exchange membrane polymer unit, and y is a positive integer; y = y1 + y2 + y3 + y4 + y5 + y6 + y7 + y8, y:x = 20 - 200, x and y 1-8 All are within 10 million; y1, y2, y3, y4, y5, y6, y7, and y8 are the numbers of phenyl monomers attached to different benzene rings of Ar1, and are all integers greater than zero.

2. The branched polyarylpiperidine anion exchange membrane according to claim 1, characterized in that: The three-dimensional spatial structure monomer is octaphenyl POSS, with the chemical name 1,3,5,7,9,11,13,15-octaphenylpentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane, CAS number 5256-79-1, and its structural formula is as follows: ； The phenyl monomer has one of the following structural formulas: 。 3. A method for preparing a branched polyarylpiperidine anion exchange membrane as described in claim 1 or 2, characterized in that: Includes the following steps: (1) Mix the three-dimensional spatial structure monomer, phenyl monomer, N-methyl-4-piperidinone and solvent, add acid catalyst under -30℃~5℃ conditions, stir and react, add NaOH to precipitate branched polyaryl polymer; (2) The branched polyaryl polymer obtained in step (1) is mixed with a first polar solvent to obtain a polymer solution; an alkaline substance is added to the polymer solution, followed by the addition of iodoalkane / bromoalkane to carry out a quaternization reaction, and ethyl acetate is added to precipitate the polyelectrolyte resin. (3) Mix the polyelectrolyte resin obtained in step (2) with a polar solvent to obtain a film-forming liquid; cast or cast the film-forming liquid onto a substrate and dry it to obtain a branched polyarylpiperidine anion exchange membrane.

4. The preparation method according to claim 3, characterized in that: In step (1), the acid catalyst is at least one of trifluoromethanesulfonic acid, trifluoroacetic acid, acetic acid, trichloroacetic acid, methanesulfonic acid, pentafluoropropionic acid, heptafluorobutyric acid, and perfluorosulfonic acid resin. Alternatively, the stirring reaction time in step (1) is 1 to 72 hours, and the stirring reaction temperature is -10 to 10°C. Alternatively, the solvent in step (1) may be dichloromethane; Alternatively, in step (1), the molar ratio of the three-dimensional spatial structure monomer: phenyl monomer: N-methyl-4-piperidinone: solvent: acid catalyst is 5~50:1:1.2~1.6:6.24~12.48:11.53~14.

99.

5. The preparation method according to claim 3, characterized in that: In step (2), the first polar solvent is at least one of tetrahydrofuran, acetonitrile, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide; Alternatively, in step (2), the mass ratio of branched polyaryl polymer: alkaline substance: iodoalkanes / bromoalkanes is 1:(0.5~8):(0.5~8). Alternatively, the quaternization reaction time in step (2) is 12~72h, and the quaternization reaction temperature is -10~50℃.

6. The preparation method according to claim 3, characterized in that: In step (3), the drying temperature is 5~200℃ and the drying time is 0.1~72h; Alternatively, the polar solvent in step (3) is dimethyl sulfoxide (DMSO); Alternatively, in step (3), the mass ratio of polyelectrolyte resin to polar solvent is 1:20; Alternatively, the substrate in step (3) can be a glass plate or a polytetrafluoroethylene plate.

7. The preparation method according to any one of claims 3 to 6, characterized in that: The specific steps are as follows: Preparation of S1 branched polyarylpiperidine polymer: terphenyl, N-methyl-4-piperidinone and a three-dimensional monomer were added to dichloromethane solvent and stirred with a mechanical stirrer for 30 min under ice-water bath conditions. Then, trifluoroacetic acid and trifluoromethanesulfonic acid were added dropwise. After reacting for 6-8 h, the resulting viscous solution was poured into a 5 mol / L NaOH solution, and a white to pale yellow polymer precipitated. The polymer was crushed, washed repeatedly with deionized water until neutral, and finally dried to obtain the branched polyarylene piperidine polymer P-PTPa-x. In step S1, the molar ratio of the three-dimensional spatial structure monomer to p-terphenyl is (0.5~2):(99.5~98), the molar ratio of p-terphenyl to N-methyl-4-piperidinone is 1:(1.3~1.5), the molar ratio of trifluoroacetic acid to N-methyl-4-piperidinone is 1:(1.1~1.2), the molar ratio of trifluoromethanesulfonic acid to N-methyl-4-piperidinone is (9.3~10):1, and 11~12 mmol of N-methyl-4-piperidinone is added for every 5 mL of dichloromethane. S2 OH - Preparation of type-3 anion exchange membranes: 1) Branched polyarylpiperidine polymer P-PTPa-x was added to dimethyl sulfoxide and stirred at room temperature for 30 min. Then K2CO3 was added and stirred at room temperature for 10 min. Then CH3I was added and the mixture was stirred in the dark at room temperature for 24-48 h. The resulting yellow viscous solution was added to ethyl acetate, and a white precipitate was obtained. The precipitate was filtered, washed three times with deionized water, and dried at 80 °C for 12 h to obtain quaternized polyarylpiperidine polymer P-PTPb-x (I - ); Wherein, the solid-liquid ratio of P-PTPa-x and CH3I is 1:1 (g:mL), the mass ratio of P-PTPa-x and K2CO3 is 1:1, the solid-liquid ratio of P-PTPa-x and dimethyl sulfoxide is 1:30 (g:mL), and the solid-liquid ratio of P-PTPa-x and ethyl acetate is 1:200 (g:mL). 2) P-PTPb-x (I - The solution was ultrasonically dissolved in dimethyl sulfoxide, filtered using a 0.8 μm polytetrafluoroethylene (PTFE) filter, ultrasonically defoamed and allowed to stand, then dropped onto a glass plate and dried at 80 °C for 5 h to obtain an I- form anion exchange membrane with a thickness of 60~70 μm. Among them, the P-PTPb-x (I - The solid-liquid ratio of dimethyl sulfoxide (DMSO) to dimethyl sulfoxide (DMSO) is 1:(14~16) g:mL. 3) Will I - The anion exchange membrane in this form was peeled off from the glass plate, immersed in a 1 mol / L NaOH solution for 48 hours, and then washed with deionized water to obtain OH⁻. - The anion exchange membrane is a branched polyarylpiperidine anion exchange membrane; subsequently, the membrane is stored by immersing it in degassed deionized water.

8. The preparation method according to claim 7, characterized in that: In step S2, OH - The structural formula of the type anion exchange membrane is as follows: 。 9. The application of the branched polyarylpiperidine anion exchange membrane as described in claim 1 or 2 in anion exchange membrane water electrolysis.

10. The application of the branched polyarylpiperidine anion exchange membrane as described in claim 1 or 2 in an anion exchange membrane alkaline water electrolyzer.

Images