A method for preparing an anion exchange membrane containing carboxylated Chaogel base

Abstract

The present invention discloses a preparation method of Chaogel base containing carboxyl group and its anion exchange membrane. The present invention relates to the technical field of ion exchange membrane preparation. The preparation method of the carboxyl group-containing anion exchange membrane includes steps of synthesizing Chaogel base containing carboxyl group, synthesizing polybenzimidazole polymer containing Chaogel base, synthesizing anion exchange membrane polymer containing Chaogel base, and preparing a dense anion exchange membrane containing Chaogel base. The advantages of the present invention are as follows: By reacting specific aminomethylbenzoic acid with dimethoxymethane and using trifluoroacetic acid as a solvent and catalyst, Chaogel base containing carboxyl group is synthesized, which not only improves the purity and stability of the product, but also enables Chaogel base containing carboxyl group to be more effectively introduced into the polybenzimidazole polymer, increases the porosity of the polybenzimidazole polymer, and thus improves the electrochemical performance and mechanical stability of the anion exchange membrane.

Description

Technical Field

[0001] The present invention relates to the technical field of ion exchange membrane preparation, and specifically to a method for preparing an anion exchange membrane containing carboxylated chaotrope base. Background Art

[0002] As a core material for electrochemical energy conversion and storage devices such as fuel cells, flow batteries, and electrolyzers, ion exchange membranes have broad application prospects in clean energy, energy conservation and emission reduction, energy conversion and storage, etc. As a key component in energy conversion devices, the ion exchange membrane must allow ions to migrate efficiently between the cathode and anode of the membrane. For anion exchange membranes (AEMs), it is required to have high ionic conductivity, high thermal stability, high mechanical stability, high chemical stability, and high electrochemical stability under working conditions. Currently, one of the main methods to increase conductivity is to increase the ion exchange capacity (IEC) of the polymer membrane. However, as the number of cationic groups increases, the water absorption rate of the AEM also increases, resulting in membrane swelling, which reduces its mechanical stability and dimensional stability. At low ion exchange capacities, the extensive hydrophobic polymer matrix structure also leads to tortuous and disconnected ion conduction pathways, hindering the ion movement pathway and causing a rapid decline in ionic conductivity. Therefore, how to efficiently organize cationic groups in the membrane to construct an anion transport channel and promote the transport of hydroxide ions has become the key to the industrial application of AEM membranes. Therefore, it is of great significance to design an ion exchange membrane with low cost and high performance. For this purpose, we propose a method for preparing an anion exchange membrane containing carboxylated chaotrope base. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing an anion exchange membrane containing carboxylated chaotrope base.

[0004] To achieve the above purpose, the present invention provides the following technical solution: A method for preparing an anion exchange membrane containing carboxylated chaotrope base, including carboxylated chaotrope base, wherein the carboxylated chaotrope base is prepared by reacting specific aminomethylbenzoic acid with dimethoxymethane, and the methyl and carboxyl groups have specific positions on the chaotrope base molecule. The chemical structure of the carboxylated chaotrope base is:

[0005] ;

[0006] The purification method of the carboxylated chaotrope base includes adjusting the solution to a specific pH value after polymerization is completed;

[0007] The specific aminomethylbenzoic acid has any of the following monomer structures:

[0008] ;

[0009] The carboxyl-containing Chaogel base uses trifluoroacetic acid as a solvent and a catalyst during the preparation process.

[0010] The preparation method includes the following steps:

[0011] Step 1: Synthesize the carboxyl-containing Chaogel base. Using trifluoroacetic acid as a solvent and a catalyst, mix aminomethylbenzoic acid and dimethoxymethane according to the feeding ratio, and carry out a synthesis reaction to obtain the carboxyl-containing Chaogel base.

[0012] Step 2: Synthesize the polybenzimidazole polymer containing Chaogel base. Using polyphosphoric acid and methanesulfonic acid as solvents and phosphorus pentoxide as a dehydrating condensing agent, mix the rigidly twisted phenyltetramine monomer, biphenyltetramine, and phthalic acid monomer according to the feeding ratio, and carry out a polymerization reaction to obtain the polybenzimidazole polymer containing Chaogel base.

[0013] Step 3: Synthesize the anion exchange membrane polymer containing Chaogel base. Using dimethyl sulfoxide as a solvent, mix methyl iodide and the polybenzimidazole copolymer according to the feeding ratio, and carry out an ionization substitution reaction to obtain the anion exchange membrane polymer containing Chaogel base.

[0014] Step 4: Prepare a dense anion exchange membrane containing Chaogel base. Mix the anion exchange membrane polymer containing Chaogel base with a polar solvent to obtain a casting solution, and then form a film of the casting solution on a substrate and dry it to obtain a dense anion exchange membrane containing Chaogel base.

[0015] As a further solution of the present invention: In the above Step 1, the specific method for synthesizing the carboxyl-containing Chaogel base is to mix specific aminomethylbenzoic acid and dimethoxymethane according to a feeding ratio of m:1 to m:n, where 0 < m < 1 and 0 < n < 1. Cool down to -10°C to 5°C, dissolve for 0.1 h to 3 h, dropwise add trifluoroacetic acid within 10 minutes, and stir at room temperature for 2 h to 48 h to obtain a transparent solution. Slowly pour a certain amount of deionized water into it under vigorous stirring, and dropwise add 1 mol / L sodium bicarbonate until a solid is produced. Filter out the solid solution, wash it with water and methanol until the filtrate is neutral, collect the product, and dry it in a vacuum oven at 80°C to 120°C for 12 h to obtain the carboxyl-containing Chaogel base.

[0016] As a further solution of the present invention: In the above Step 2, the specific method for synthesizing the polybenzimidazole polymer containing Chaogel base is to mix polyphosphoric acid, phosphorus pentoxide, the rigidly twisted phenyltetramine monomer, and biphenyltetramine according to a feeding ratio of x:1 to x:y, where 0 < x < 1 and 0 < y < 1. Heat up to 90°C to 150°C and dissolve for 2 h to 12 h, then add the carboxyl-containing Chaogel base. After obtaining a homogeneous solution, heat up to 190°C to 220°C and react for 0.5 h to 12 h to obtain the polybenzimidazole polymer containing Chaogel base.

[0017] As a further aspect of the present invention: In the step three, the specific method for synthesizing the anion exchange membrane polymer containing Chaogel base is to use dimethyl sulfoxide as a solvent, and mix methyl iodide and polybenzimidazole copolymer according to a feeding ratio of a:b, where 0 < a < 10 and 0 < b < 1. Heat to 25°C to 80°C and react for 2h to 48h to obtain the anion exchange membrane polymer containing Chaogel base.

[0018] As a further aspect of the present invention: In the step four, the specific method for preparing the dense anion exchange membrane containing Chaogel base is to form a film of the casting solution on a substrate by the casting method, and dry it at 40°C to 140°C for 0.5h to 72h to obtain the dense anion exchange membrane containing Chaogel base.

[0019] As a further aspect of the present invention: In the step two, the structure of the rigid twisted phenyltetramine monomer is shown as any one of the following formulas:

[0020] ;

[0021] The structure of the phthalic acid monomer is shown as any one of the following formulas:

[0022] ;

[0023] Wherein, a carboxyl group is connected to each side of the benzene ring.

[0024] As a further aspect of the present invention: The general chemical structure formula of the anion exchange membrane containing Chaogel base is:

[0025] ;

[0026] Wherein, n is 10 to 1000, * represents the connection site, R3 is H and CH3, R4 is H and CH3,

[0027] R1 includes any combination of biphenyltetramine monomer groups and rigid twisted phenyltetramine monomer groups. The structural formula of the biphenyltetramine monomer group is:

[0028] ;

[0029] The rigid twisted phenyltetramine monomer group includes at least one of the following structural formulas:

[0030] ;

[0031] R2 is a Chaogel base structure containing ionization, including at least one of the following structural formulas:

[0032] ;

[0033] Among them, X⁻ is a stable anion.

[0034] Adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] 1. In the present invention, a carboxyl-containing Chaogel base is synthesized by reacting a specific aminomethylbenzoic acid with dimethoxymethane and using trifluoroacetic acid as a solvent and a catalyst, which not only improves the purity and stability of the product, but also enables the carboxyl-containing Chaogel base to be more effectively introduced into the polybenzimidazole polymer, increases the porosity of the polybenzimidazole polymer, and thus enhances the electrochemical performance and mechanical stability of the anion exchange membrane;

[0036] 2. In the present invention, a polybenzimidazole polymer with a specific structure is synthesized by introducing a rigid twisted phenyltetramine monomer and biphenyltetramine and combining with the carboxyl-containing Chaogel base. This polymer not only has a high porosity but also maintains a high mechanical strength, thereby optimizing the ion conduction pathway and enhancing the ionic conductivity. In addition, by precisely controlling the feed ratio and reaction conditions, the structure and properties of the polymer can be further adjusted to meet the requirements of different application scenarios;

[0037] 3. By introducing the Chaogel base unit into the polybenzimidazole main chain in the present invention, the mechanical stability and solubility of the anion exchange membrane can be improved. This improvement not only enhances the durability of the membrane but also optimizes its performance in different solvents, providing broader compatibility for the application of the anion exchange membrane in various electrochemical devices.

[0038] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, they will be obvious to those skilled in the art based on the study of the following text, and those skilled in the art can also obtain teachings from the practice of the present invention. Description of the Drawings

[0039] Figure 1 It is a schematic diagram of the steps of the preparation method of the anion exchange membrane in the embodiment of the present invention. Detailed Embodiments

[0040] The following further describes the detailed embodiments of the present invention with reference to the drawings. It should be noted here that the description of these embodiments is for helping to understand the present invention, but does not constitute a limitation to the present invention.

[0041] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] Please refer to the attached Figure 1, a method for preparing an anion exchange membrane containing carboxylated chaogel base, wherein the carboxylated chaogel base is prepared by reacting specific aminomethylbenzoic acid with dimethoxymethane, and the methyl and carboxyl groups have specific sites on the chaogel base molecule. The chemical structure of the carboxylated chaogel base is:

[0043] ;

[0044] The purification method of the carboxylated chaogel base includes adjusting the solution to a specific pH value after polymerization is completed.

[0045] In one embodiment of the present invention: the specific aminomethylbenzoic acid has any of the following monomer structures:

[0046] ;

[0047] Trifluoroacetic acid is used as a solvent and catalyst in the preparation of the carboxylated chaogel base.

[0048] It includes the following steps:

[0049] Step 1: Synthesize the carboxylated chaogel base. Using trifluoroacetic acid as a solvent and catalyst, mix the specific aminomethylbenzoic acid and dimethoxymethane according to a specific feed ratio, and carry out a synthesis reaction to obtain the carboxylated chaogel base;

[0050] Step 2: Synthesize the polybenzimidazole polymer containing chaogel base. Using polyphosphoric acid and methanesulfonic acid as solvents and phosphorus pentoxide as a dehydration condensing agent, mix the rigid twisted phenyltetramine monomer, biphenyltetramine and phthalic acid monomer according to a specific feed ratio, and carry out a polymerization reaction to obtain the polybenzimidazole polymer containing chaogel base;

[0051] Step 3: Synthesize the anion exchange membrane polymer containing chaogel base. Using dimethyl sulfoxide as a solvent, mix methyl iodide and the polybenzimidazole copolymer according to a specific feed ratio, and carry out an ionization substitution reaction to obtain the anion exchange membrane polymer containing chaogel base;

[0052] Step 4: Prepare a dense anion exchange membrane containing chaogel base. Mix the anion exchange membrane polymer containing chaogel base with a polar solvent to obtain a casting solution, and then form and dry the casting solution on a substrate to obtain a dense anion exchange membrane containing chaogel base.

[0053] In one embodiment of the present invention: In step one, the specific method for synthesizing the Chaogel base containing carboxyl groups is as follows. A specific aminomethylbenzoic acid and dimethoxymethane are mixed according to a feeding ratio of m:1 to m:n, where 0 < m < 1 and 0 < n < 1. The temperature is lowered to -10°C to 5°C, and they are dissolved for 0.1 h to 3 h. Trifluoroacetic acid is added dropwise within 10 min, and the mixture is stirred at room temperature for 2 h to 48 h to obtain a transparent solution. The solution is slowly poured into a certain amount of deionized water under vigorous stirring, and 1 mol / L sodium bicarbonate is added dropwise until a solid is produced. The solid solution is filtered out, washed with water and methanol until the filtrate is neutral, the product is collected, and dried in a vacuum oven at 80°C to 120°C for 12 h to obtain the Chaogel base containing carboxyl groups.

[0054] In one embodiment of the present invention: In step two, the specific method for synthesizing the polybenzimidazole polymer containing Chaogel base is as follows. Polyphosphoric acid, phosphorus pentoxide, a rigid twisted phenyltetramine monomer, and biphenyltetramine are mixed according to a feeding ratio of x:1 to x:y, where 0 < x < 1 and 0 < y < 1. The temperature is raised to 90°C to 150°C and dissolved for 2 h to 12 h. Then, the Chaogel base containing carboxylic acid is added. After obtaining a homogeneous solution, the temperature is further raised to 190°C to 220°C and reacted for 0.5 h to 12 h to obtain the polybenzimidazole polymer containing Chaogel base.

[0055] In one embodiment of the present invention: In step three, the specific method for synthesizing the anion exchange membrane polymer containing Chaogel base is as follows. Using dimethyl sulfoxide as a solvent, methyl iodide and the polybenzimidazole copolymer are mixed according to a feeding ratio of a:b, where 0 < a < 10 and 0 < b < 1. The temperature is raised to 25°C to 80°C and reacted for 2 h to 48 h to obtain the anion exchange membrane polymer containing Chaogel base.

[0056] In one embodiment of the present invention: In step four, the specific method for preparing a dense anion exchange membrane containing Chaogel base is as follows. The casting solution is formed into a film on a substrate by the casting method and dried at 40°C to 140°C for 0.5 h to 72 h to obtain a dense anion exchange membrane containing Chaogel base.

[0057] In one embodiment of the present invention: In step two, the structure of the rigid twisted phenyltetramine monomer is shown as any one of the following formulas:

[0058] ;

[0059] The structure of the phthalic acid monomer is shown as any one of the following formulas:

[0060] ;

[0061] Wherein, a carboxyl group is connected to each side of the benzene ring.

[0062] In one embodiment of the present invention, the chemical structure general formula of the anion exchange membrane containing chaogelian is as follows:

[0063] ;

[0064] Wherein, n is 10 to 1000, * represents the connection site, R3 is H and CH3, R4 is H and CH3,

[0065] R1 includes any combination of biphenyltetramine monomer groups and rigid twisted phenyltetramine monomer groups. The structural formula of the biphenyltetramine monomer group is:

[0066] ;

[0067] The rigid twisted phenyltetramine monomer group includes at least one of the following structural formulas:

[0068] ;

[0069] R2 is a chaogelian structure containing ionization, including at least one of the following structural formulas:

[0070] ;

[0071] Wherein, X− is a stable anion.

[0072] Example 1: Under a nitrogen atmosphere, 3-amino-4-methylbenzoic acid (1.37 g, 10 mmol) was dissolved in dimethoxymethane (1.84 mL, 50 mmol) at room temperature. After complete dissolution, the temperature was lowered to 5 °C and dissolved for 1 h. An appropriate amount of trifluoroacetic acid (30 mL) was added dropwise within 10 min, and the mixture was stirred at room temperature for 48 h to obtain a transparent solution. The solution was slowly poured into a certain amount of deionized water under vigorous stirring, and 1 mol / L sodium bicarbonate was added dropwise until a large amount of solid was produced. The solid solution was filtered out and washed several times with water and methanol until the filtrate was neutral. The product was collected and dried in a vacuum oven at 80 - 120 °C for 12 h to obtain Chaogel base containing carboxylic acid, 4,10-dimethyl-6H,12H-5,11-diaminodibenzo[b,f][1,5]diazocine-1,7-dicarboxylic acid (TB1-COOH). 85% polyphosphoric acid was added to a three-necked flask, and nitrogen was introduced to exclude oxygen. 3,3'-diaminobenzidine was added to the three-necked flask, and the temperature was raised to 120 °C and dissolved for 3 h. Then 4,10-dimethyl-6H,12H-5,11-diaminodibenzo[b,f][1,5]diazocine-1,7-dicarboxylic acid (TB1-COOH) was added to make the total concentration of the monomers 15 wt%. After obtaining a homogeneous solution, the temperature was raised to 200 °C and reacted for 12 h. When the reaction solution became very viscous and climbed the rod, the polymerization reaction ended. The high-viscosity reaction solution was precipitated in water to obtain a filamentous polymer. After neutralizing with excessive NaOH, it was washed with water several times and dried to obtain a solid polymer. The obtained solid polymer was placed in a round-bottom single-necked flask, and methyl iodide and the polybenzimidazole polymer containing Chaogel base were mixed at a feeding ratio of 10:1 using N-methyl-2-pyrrolidone or dimethyl sulfoxide as the solvent for an ionization substitution reaction;

[0073] Magnetic stirring was carried out at 60 °C for 24 h. The solution obtained from the reaction was precipitated in acetone and washed several times with acetone. The obtained precipitated polymer was dissolved and mixed with an excessive NaOH solution. By stirring the polymer, the exchange of iodide ions and hydroxide ions was achieved. Finally, the polymer was precipitated, rinsed with water, and dried to obtain an anion exchange membrane polymer containing Chaogel base. The degree of ionization can be achieved by controlling the amount of methyl iodide or by controlling the ionization time. The obtained polymer was dissolved in dimethyl sulfoxide to form a 3 wt% transparent solution. The casting solution was cast onto a glass plate and dried at 60 °C for 24 h to form a film. The film was immersed in a 1 mol / L dilute sulfuric acid solution for 24 h, and then immersed and washed with deionized water until neutral to obtain an anion exchange membrane containing Chaogel base.

[0074] Example 2: Under a nitrogen atmosphere, 4-amino-3-methylbenzoic acid (1.37 g, 10 mmol) was dissolved in dimethoxymethane (1.84 mL, 50 mmol) at room temperature. After complete dissolution, the temperature was lowered to 5 °C and dissolved for 1 h. An appropriate amount of trifluoroacetic acid (30 mL) was added dropwise within 10 min, and the mixture was stirred at room temperature for 48 h to obtain a transparent solution. The solution was slowly poured into a certain amount of deionized water under vigorous stirring, and 1 mol / L sodium bicarbonate was added dropwise until a large amount of solid was produced. The solid solution was filtered out and washed several times with water and methanol until the filtrate was neutral. The product was collected and dried in a vacuum oven at 80-120 °C for 12 h to obtain a chao gel base containing carboxylic acid, 4,10-dimethyl-6H,12H-5,11-diaminodibenzo[b,f][1,5]diazocine-2,8-dicarboxylic acid (TB2-COOH). 85% polyphosphoric acid was added to a three-necked flask, and nitrogen was introduced to exclude oxygen. 3,3'-diaminobenzidine was added to the three-necked flask, and the temperature was raised to 120 °C and dissolved for 3 h. Then, 4,10-dimethyl-6H,12H-5,11-diaminodibenzo[b,f][1,5]diazocine-2,8-dicarboxylic acid (TB2-COOH) was added to make the total concentration of the monomers 15 wt%. After obtaining a homogeneous solution, the temperature was raised to 200 °C and reacted for 12 h. When the reaction solution became very viscous and climbed the rod, the polymerization reaction ended. The high-viscosity reaction solution was precipitated in water to obtain a filamentous polymer. After neutralization with excess NaOH, it was washed with water several times and dried to obtain a solid polymer. The obtained solid polymer was placed in a round-bottom single-necked flask, and iodomethane and the polybenzimidazole polymer containing chao gel base were mixed at a feed ratio of 10:1 using N-methyl-2-pyrrolidone or dimethyl sulfoxide as the solvent for an ionization substitution reaction;

[0075] Magnetic stirring was carried out at 60 °C for 24 h. The solution obtained from the reaction was precipitated in acetone and washed several times with acetone. The obtained precipitated polymer was dissolved and mixed with an excess NaOH solution. By stirring the polymer, the exchange of iodide ions and hydroxide ions was achieved, and finally the polymer was precipitated, rinsed with water, and dried to obtain an anion exchange membrane polymer containing chao gel base. The degree of ionization can be achieved by controlling the amount of iodomethane or by controlling the ionization time. The obtained polymer was dissolved in dimethyl sulfoxide to form a 3 wt% transparent solution. The casting solution was cast onto a glass plate and dried at 60 °C for 24 h to form a film. The film was immersed in a 1 mol / L dilute sulfuric acid solution for 24 h, and then immersed and washed with deionized water until neutral to obtain a fluorene-based anion exchange membrane containing chao gel base.

[0076] Example 3: Under a nitrogen atmosphere, 3-amino-2-methylbenzoic acid (1.37 g, 10 mmol) was dissolved in dimethoxymethane (1.84 mL, 50 mmol) at room temperature. After complete dissolution, the temperature was lowered to 5 °C and dissolved for 1 h. An appropriate amount of trifluoroacetic acid (30 mL) was added dropwise within 10 min, and the mixture was stirred at room temperature for 48 h to obtain a transparent solution. Under vigorous stirring, it was slowly poured into a certain amount of deionized water, and 1 mol / L sodium bicarbonate was added dropwise until a large amount of solid was produced. The solid solution was filtered out and washed several times with water and methanol until the filtrate was neutral. The product was collected and dried in a vacuum oven at 80 - 120 °C for 12 h to obtain a Chaogel base containing carboxylic acid, 4,10-dimethyl-6H,12H-5,11-diaminodibenzo[b,f][1,5]diazocine-3,9-dicarboxylic acid (TB3-COOH). 85% polyphosphoric acid was added to a three-necked flask, and nitrogen was introduced to exclude oxygen. 3,3'-diaminobenzidine was added to the three-necked flask, and the temperature was raised to 120 °C and dissolved for 3 h. Then 4,10-dimethyl-6H,12H-5,11-diaminodibenzo[b,f][1,5]diazocine-3,9-dicarboxylic acid (TB3-COOH) was added to make the total concentration of the monomers 15 wt%. After obtaining a homogeneous solution, the temperature was raised to 200 °C and reacted for 12 h. When the reaction solution became very viscous and climbed the rod, the polymerization reaction ended. The high-viscosity reaction solution was precipitated in water to obtain a filamentous polymer. After neutralizing with excess NaOH, it was washed with water several times and dried to obtain a solid polymer. The obtained solid polymer was placed in a round-bottom single-necked flask, and iodomethane and the polybenzimidazole polymer containing Chaogel base were mixed at a feeding ratio of 10:1 using N-methyl-2-pyrrolidone or dimethyl sulfoxide as the solvent for an ionized substitution reaction;

[0077] Magnetic stirring was carried out at 60 °C for 24 h. The solution obtained from the reaction was precipitated in acetone and washed several times with acetone. The obtained precipitated polymer was dissolved and mixed with an excess NaOH solution. By stirring the polymer, the exchange of iodide ions and hydroxide ions was achieved, and finally the polymer was precipitated, rinsed with water, and dried to obtain a Chaogel base-containing anion exchange membrane polymer. The degree of ionization can be achieved by controlling the amount of iodomethane or by controlling the ionization time. The obtained polymer was dissolved in dimethyl sulfoxide to form a 3 wt% transparent solution. The casting solution was cast onto a glass plate and dried at 60 °C for 24 h to form a film. The film was immersed in a 1 mol / L dilute sulfuric acid solution for 24 h, and then immersed and washed with deionized water until neutral to obtain a spiro group-containing Chaogel base anion exchange membrane.

[0078] Example 4: Under a nitrogen atmosphere, 2-amino-5-methylbenzoic acid (1.37 g, 10 mmol) was dissolved in dimethoxymethane (1.84 mL, 50 mmol) at room temperature. After complete dissolution, the temperature was lowered to 5 °C and dissolved for 1 h. An appropriate amount of trifluoroacetic acid (30 mL) was added dropwise within 10 min, and the mixture was stirred at room temperature for 48 h to obtain a transparent solution. The solution was slowly poured into a certain amount of deionized water under vigorous stirring, and 1 mol / L sodium bicarbonate was added dropwise until a large amount of solid was produced. The solid solution was filtered out and washed several times with water and methanol until the filtrate was neutral. The product was collected and dried in a vacuum oven at 80 - 120 °C for 12 h to obtain a Chaogel base containing carboxylic acid, 2,8-dimethyl-6H,12H-5,11-diaminodibenzo[b,f][1,5]diazocine-4,10-dicarboxylic acid (TB4-COOH). 85% polyphosphoric acid was added to a three-necked flask, and nitrogen was introduced to exclude oxygen. 3,3'-diaminobenzidine was added to the three-necked flask, and the temperature was raised to 120 °C and dissolved for 3 h. Then 2,8-dimethyl-6H,12H-5,11-diaminodibenzo[b,f][1,5]diazocine-4,10-dicarboxylic acid (TB4-COOH) was added to make the total concentration of the monomers 15 wt%. After obtaining a homogeneous solution, the temperature was raised to 200 °C and reacted for 12 h. When the reaction solution became very viscous and climbed the rod, the polymerization reaction ended. The high-viscosity reaction solution was precipitated in water to obtain a filamentous polymer. After neutralization with excess NaOH, it was washed with water several times and dried to obtain a solid polymer. The obtained solid polymer was placed in a round-bottom single-necked flask, and iodomethane and the polybenzimidazole polymer containing Chaogel base were mixed at a feeding ratio of 10:1 using N-methyl-2-pyrrolidone or dimethyl sulfoxide as the solvent for an ionization substitution reaction;

[0079] Magnetic stirring was carried out at 60 °C for 24 h. The solution obtained from the reaction was precipitated in acetone and washed with acetone several times. The obtained precipitated polymer was dissolved and mixed with an excess NaOH solution. By stirring the polymer, the exchange of iodide ions and hydroxide ions was achieved, and finally the polymer was precipitated, rinsed with water, and dried to obtain a Chaogel base-containing anion exchange membrane polymer. The degree of ionization can be achieved by controlling the amount of iodomethane or by controlling the ionization time. The obtained polymer was dissolved in dimethyl sulfoxide to form a 3 wt% transparent solution. The casting solution was cast onto a glass plate and dried at 60 °C for 24 h to form a film. The film was immersed in a 1 mol / L dilute sulfuric acid solution for 24 h, and then immersed and washed with deionized water until neutral to obtain a spiro-group-containing Chaogel base anion exchange membrane.

[0080] The above front, back, left, right, up, and down are all based on the Figure 1 in the accompanying drawings of the specification. Taking the perspective of the observer as the standard, the side of the device facing the observer is defined as the front, and the left side of the observer is defined as the left, and so on.

[0081] In the description of the present invention, it should be understood that the orientation and positional relationships indicated by the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation and positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating and implying that the devices and elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the protection scope of the present invention.

[0082] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments.

[0083] For those skilled in the art, without departing from the principle and spirit of the present invention, various changes, modifications, substitutions, and variations made to these embodiments still fall within the protection scope of the present invention.

Claims

1. A preparation method of an anion exchange membrane containing carboxylated Chaogel base, including carboxylated Chaogel base, characterized in that: The carboxyl-containing Chaogel base is prepared by reacting aminomethylbenzoic acid with dimethoxymethane, and the methyl group and carboxyl group have specific positions on the Chaogel base molecule. The chemical structure of the carboxyl-containing Chaogel base is as follows: ； The purification method of the carboxyl-containing Chaogel base includes adjusting the solution to a pH value after polymerization is completed; The aminomethylbenzoic acid has any of the following monomer structures: ； Trifluoroacetic acid is used as a solvent and catalyst in the preparation of the carboxyl-containing Chaogel base; It includes the following steps: Step 1: Synthesize the carboxyl-containing Chaogel base. Using trifluoroacetic acid as a solvent and catalyst, mix aminomethylbenzoic acid and dimethoxymethane according to the feed ratio, and carry out a synthesis reaction to obtain the carboxyl-containing Chaogel base; Step 2: Synthesize the polybenzimidazole polymer containing Chaogel base. Using polyphosphoric acid and methanesulfonic acid as solvents and phosphorus pentoxide as a dehydrating condensing agent, mix the rigid twisted phenyltetramine monomer, biphenyltetramine, and phthalic acid monomer according to the feed ratio, and carry out a polymerization reaction to obtain the polybenzimidazole polymer containing Chaogel base; Step 3: Synthesize the anion exchange membrane polymer containing Chaogel base. Using dimethyl sulfoxide as a solvent, mix methyl iodide and the polybenzimidazole copolymer according to the feed ratio, and carry out an ionization substitution reaction to obtain the anion exchange membrane polymer containing Chaogel base; Step 4: Prepare a dense anion exchange membrane containing Chaogel base. Mix the anion exchange membrane polymer containing Chaogel base with a polar solvent to obtain a casting solution, and then form a film of the casting solution on a substrate and dry it to obtain a dense anion exchange membrane containing Chaogel base.

2. The preparation method of an anion exchange membrane containing carboxyl-containing Chaogel base according to claim 1, characterized in that: In the above Step 1, the specific method for synthesizing the carboxyl-containing Chaogel base is to mix aminomethylbenzoic acid and dimethoxymethane according to a feed ratio of m:1 to m:n, where 0 < m < 1 and 0 < n < 1. Cool down to -10°C to 5°C, dissolve for 0.1 h to 3 h, add trifluoroacetic acid dropwise within 10 minutes, and stir at room temperature for 2 h to 48 h to obtain a transparent solution. Slowly pour a certain amount of deionized water into it under vigorous stirring, dropwise add 1 mol / L sodium bicarbonate until a solid is produced, filter out the solid solution, wash it with water and methanol until the filtrate is neutral, collect the product, and dry it in a vacuum oven at 80°C to 120°C for 12 h to obtain the carboxyl-containing Chaogel base.

3. The preparation method of an anion exchange membrane containing carboxyl Chaogel base according to claim 1, characterized in that: In the above Step 2, the specific method for synthesizing the polybenzimidazole polymer containing Chaogel base is to mix polyphosphoric acid, phosphorus pentoxide, the rigid twisted phenyltetramine monomer, and biphenyltetramine according to a feed ratio of x:1 to x:y, where 0 < x < 1 and 0 < y < 1. Heat up to 90°C to 150°C and dissolve for 2 h to 12 h, then add the carboxyl-containing Chaogel base. After obtaining a homogeneous solution, heat up to 190°C to 220°C and react for 0.5 to 12 h to obtain the polybenzimidazole polymer containing Chaogel base.

4. The preparation method of an anion exchange membrane containing carboxyl Chaogel base according to claim 1, characterized in that: In the third step, the specific method for synthesizing the anion exchange membrane polymer containing chaogel base is as follows: using dimethyl sulfoxide as a solvent, mixing methyl iodide and polybenzimidazole copolymer according to a feeding ratio of a:b, where 0 < a < 10 and 0 < b < 1, heating to 25°C to 80°C and reacting for 2h to 48h to obtain the anion exchange membrane polymer containing chaogel base.

5. The preparation method of an anion exchange membrane containing carboxyl chaoer base according to claim 1, characterized in that: In the fourth step, the specific method for preparing the dense anion exchange membrane containing chaogel base is as follows: forming a film of the casting solution on a substrate by the casting method and drying at 40°C to 140°C for 0.5h to 72h to obtain the dense anion exchange membrane containing chaogel base.

6. The preparation method of an anion exchange membrane containing carboxyl-containing Chaogel base according to claim 1, characterized in that: In the second step, the structure of the rigid twisted phenyltetramine monomer is shown as any one of the following formulas: ; The phthalic acid monomer has a structure shown by any one of the following formulas: ； Among them, each side of the benzene ring is connected to a carboxyl group.

7. A method for preparing an anion exchange membrane containing carboxyl-containing Chaogel base according to claim 1, characterized in that: The chemical structure general formula of the anion exchange membrane containing chaogel base is: ； Among them, n is 10 to 1000, * represents the connection site, R3 is H and CH3, R4 is H and CH3, R1 includes any combination of biphenyltetramine monomer groups and rigid twisted phenyltetramine monomer groups, and the structural formula of the biphenyltetramine monomer group is: ； The rigid twisted phenyltetramine monomer group includes at least one of the following structural formulas: ； R2 is a chaogel base structure containing ionization, including at least one of the following structural formulas: ； Among them, X- is a stable anion.

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