High-performance and high-chemical-stability composite anion exchange membrane containing rigid structure as well as preparation method and application of high-performance and high-chemical-stability composite anion exchange membrane

Abstract

The invention discloses a high-performance and high-chemical-stability composite anion exchange membrane containing a rigid structure, a preparation method and application, and belongs to the technical field of high polymer chemistry and alkaline anion exchange membranes. The composite anion exchange membrane is prepared by taking a synthetic polymer as a base material, performing ionization treatment and adding 4-tert-butyl calix [6] arene as a functional additive. 4-tert-butylcalix [6] arene has a macrocyclic steric hindrance phenol type structure to endow the polymer with the characteristic of oxidative degradation resistance, the polymer has an excellent scavenging effect on active free radicals, especially hydroxyl free radicals, in a fuel cell environment, and meanwhile, the rigid cavity structure can increase the free volume in a polymer membrane and is beneficial to improving the ionic conductivity. The preparation method disclosed by the invention is simple, mild in condition and low in cost, avoids the steps of high-toxicity chloromethyl etherification, noble metal catalyst use, complex polymerization and the like related to a common method, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the fields of polymer chemistry and basic anion exchange membrane technology, specifically relating to a high-performance, highly chemically stable composite anion exchange membrane with a rigid structure and its preparation method, with applications in hydrogen fuel cells and water electrolysis for hydrogen production. Background Technology

[0002] Hydrogen energy, as a highly efficient and clean secondary energy source, holds strategic significance in the global energy transition. Hydrogen fuel cells, as a key carrier for converting hydrogen energy into electrical energy, have garnered renewed attention in both basic research and industrial applications. Alkaline anion exchange membrane fuel cells (AEMFCs), due to their high pH environment advantage, can utilize inexpensive non-precious metal catalysts and have reduced corrosion resistance requirements for fuel cell systems. Furthermore, the reverse transport of hydroxide ions effectively inhibits fuel permeation, significantly reducing operating costs and highlighting their economic viability and application potential, making them one of the hottest research topics in recent years.

[0003] Anion exchange membrane (AEM) is the core material of AEMFC, responsible for conducting OH-. - Ions react with the anode and cathode, and their ionic conductivity and chemical stability directly affect the performance and lifespan of fuel cells. From a chemical structure perspective, AEM mainly consists of a polymer backbone, cationic functional groups, and anionic OH groups. - composition.

[0004] Aryl ether polymers (such as polyethersulfone, polyetherketone, and polyphenylene ether) are widely used in AEMs due to their excellent mechanical and thermal stability. However, because their main chains contain heteroatoms such as N, O, and S, they are susceptible to hydroxyl radicals (OH-). - Nucleophilic attack triggers degradation of the polymer backbone and functional groups, leading to OH... - The ionic conductivity decreases. To address this, researchers have developed various methods to prepare AEMs with excellent performance and high chemical stability, such as superacid catalysis, Suzuki coupling reaction, and Diels-Alder polymerization. However, these synthetic methods typically use noble metal catalysts, and the polymerization and subsequent functionalization processes are quite complex. Furthermore, polymer materials suffer from oxidative aging during use in the presence of oxygen or under heat; therefore, adding antioxidants is an effective strategy to delay the oxidation of polymer materials.

[0005] Calixarenes are a class of cyclic polymers formed from phenols and formaldehyde. They are cup-shaped, with a tightly packed and regularly arranged phenolic hydroxyl group at the bottom and a hydrophobic alkyl group at the top, possessing a unique cavity structure. As the third-generation supramolecular host compound after crown ethers and cyclodextrins, calixarenes not only have a large relative molecular mass and good thermal and chemical stability, but their phenolic hydroxyl groups on the benzene ring also have a certain antioxidant capacity. Taking p-tert-butylcalixarene as an example... Figure 6 As shown, its mechanism of action is to react with the free radicals R· or ROO· generated by the polymer material under the action of heat and oxygen, thereby preventing the polymer's auto-oxidation chain reaction. At the same time, the generated phenoxy free radicals can form a resonance structure with the large π conjugated system of aromatic rings and stabilize it, thus effectively delaying the aging and degradation of the material.

[0006] Therefore, it is of great significance to develop an anion exchange membrane that is simple to prepare, has excellent performance, and possesses good chemical stability in order to address the aforementioned problems. Summary of the Invention

[0007] This invention relates to a high-performance, chemically stable composite anion exchange membrane with a rigid structure and its preparation method, belonging to the fields of polymer chemistry and basic anion exchange membrane technology. The composite anion exchange membrane has a thickness of 80-120µm and is prepared by using a synthetic polymer as the matrix material, through ionization treatment and the addition of calixarene as a functional additive; wherein the amount of calixarene added is 0.5-5wt% of the dry weight of the polymer, and the calixarene is 4-tert-butylcalix[6]arene. The macrocyclic sterically hindered phenolic structure of 4-tert-butylcalix[6]arene endows it with antioxidant degradation properties, and has an excellent scavenging effect on active free radicals, especially hydroxyl free radicals, in the fuel cell environment. At the same time, the rigid cavity structure can increase the free volume inside the polymer membrane, which is beneficial to improving the ionic conductivity. The preparation steps of the composite anion exchange membrane are as follows: (1) First, a polymer solid without heteroatoms in the main chain is obtained by free radical polymerization reaction; (2) Then, imidazole groups and quaternary ammonium groups are grafted by nucleophilic reaction for further ionization: the molar ratio of imidazole groups to quaternary ammonium groups is a:b (a and b are both integers from 1 to 9 and a+b=10); (3) Finally, calixarene is introduced as an additive to prepare a chlorine-type composite anion exchange membrane, which is then converted into a hydroxide-type composite anion exchange membrane by alkaline solution treatment.

[0008] The preparation method of this invention is simple, mild, and low-cost, avoiding the steps involved in commonly used methods such as highly toxic chloromethyl etherification, use of precious metal catalysts, and complex polymerization. By adjusting the feeding ratio of imidazole groups and quaternary ammonium groups to adjust the concentration and degree of crosslinking of functional groups, and introducing 4-tert-butylcalix[6] aromatic hydrocarbon as a functional additive, the prepared composite anion exchange membrane has excellent ionic conductivity and chemical stability, and is suitable for fuel cells and water electrolysis hydrogen production.

[0009] The technical solution of this invention:

[0010] A high-performance, high-chemical-stability composite anion exchange membrane with a rigid structure, referred to as a composite anion exchange membrane, has a thickness of 80-120µm. It is prepared by using a synthesized polymer as the matrix material, through ionization treatment and the addition of calixarene as a functional additive. The amount of calixarene added is 0.5-5wt% of the dry weight of the polymer, and the calixarene is 4-tert-butylcalix[6]arene.

[0011] A method for preparing a high-performance, highly chemically stable composite anion exchange membrane with a rigid structure includes the following steps:

[0012] S1: Reactive monomer 1, reactive monomer 2, and initiator are co-dissolved in an organic solvent, stirred evenly, and subjected to free radical polymerization under an inert atmosphere to obtain a first reaction solution. The first reaction solution is added dropwise to a precipitant to precipitate a precipitate. The precipitate is washed and dried to obtain a polymer solid.

[0013] S2: Dissolve the polymer solid obtained in step S1 in a polar solvent at room temperature to obtain a polymer solution, and carry out a functionalization reaction to graft imidazole groups and quaternary ammonium groups; the molar ratio of imidazole groups to quaternary ammonium groups is a:b, where a and b are both integers from 1 to 9 and a+b=10, to prepare a second reaction solution;

[0014] S3: Introduce the functional additive into the second reaction solution from step S2, stir until homogeneous, and obtain the third reaction solution. The amount of the functional additive is 0.5~5 wt% of the dry weight of the polymer in the second reaction solution.

[0015] S4: The third reaction solution described in step S3 is used to form a film on a substrate, and after drying, a chloride-type composite anion exchange membrane is obtained.

[0016] S5: Immerse the chloride-type composite anion exchange membrane obtained in step S4 in an alkaline solution at room temperature for a period of time, wash with deionized water until the pH of the washing solution is 7, and dry to obtain the hydroxide-type composite anion exchange membrane.

[0017] Further, in step S1, the reaction monomer 1 is one of the compounds shown in formula (I), and the reaction monomer 2 is 4-chloromethylstyrene; the molar ratio of reaction monomer 1 to reaction monomer 2 is 1~5:1.

[0018] or

[0019] Formula (I)

[0020] Further, the initiator in step S1 is azobisisobutyronitrile, azobisisobutyronitrile, N,N-dimethylacetamide or azobiscyclohexanenitrile; the amount of initiator used accounts for 0.2~2wt% of the total mass of the reaction monomers.

[0021] Further, the organic solvent mentioned in step S1 is tetrahydrofuran, N-methylpyrrolidone, N,N-dimethylformamide, or dimethyl sulfoxide.

[0022] Furthermore, the inert atmosphere mentioned in step S1 is nitrogen, argon, or helium.

[0023] Furthermore, the free radical polymerization reaction temperature in step S1 is 60~80℃; the free radical polymerization reaction time is 12~24h.

[0024] Further, the precipitant in step S1 is deionized water, methanol, ethanol or isopropanol.

[0025] Further, the polar solvent in step S2 is N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide.

[0026] Furthermore, in step S2, the concentration of the polymer solution is 10~30wt%.

[0027] Further, in step S2, the compound selected for the imidazole group is one of N-methylimidazolium, N-octylimidazolium, N-cyclohexylimidazolium, and 1,2-dimethylimidazolium; and the compound selected for the quaternary ammonium group is one of N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethyl-1,3-propanediamine, and N,N,N',N'-tetramethyl-1,6-hexanediamine.

[0028] Furthermore, the molar amount of a+b is equal to the molar amount of reactant monomer 2 in step S1.

[0029] Furthermore, in step S2, the functionalization reaction is carried out at a temperature of 40-60°C for 10-20 hours.

[0030] Furthermore, the functional additive mentioned in step S3 is 4-tert-butylcalix[6] aromatic hydrocarbon.

[0031] Furthermore, the film-forming method described in step S4 is coating by scraping, casting, or pouring.

[0032] Furthermore, the drying conditions described in steps S1, S4, and S5 are all vacuum drying at a temperature of 40~60℃ and a vacuum drying time of 12~24h.

[0033] Further, the alkali in the alkaline solution in step S5 is KOH or NaOH, with a concentration of 0.5 mol / L to 1 mol / L; the soaking time is 24 to 48 hours.

[0034] The high-performance, chemically stable composite anion exchange membrane with a rigid structure prepared by the above method is applied to fuel cells and water electrolysis for hydrogen production.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] (1) Compared with commonly used polyether matrix materials, the polymer backbone synthesized in this invention does not contain heteroatoms such as N, O, and S. By eliminating the nucleophilic attack sites of hydroxyl (OH⁻), the risk of backbone degradation is significantly reduced.

[0037] (2) This invention achieves a dual improvement in ion transport and chemical stability by introducing 4-tert-butylcalix[6] aromatics, which have a synergistic optimization effect. The rigid cavity structure of 4-tert-butylcalix[6] aromatics increases the free volume inside the polymer membrane, reduces the ion migration energy barrier, and is beneficial to improving ion conductivity; at the same time, its macrocyclic steric phenolic structure endows it with antioxidant degradation properties. By adjusting the feeding ratio of imidazole groups and quaternary ammonium groups to adjust the concentration of functional groups and the degree of crosslinking, the introduced 4-tert-butylcalix[6] aromatics are used as functional additives. The composite anion exchange membrane has excellent ion conductivity and chemical stability, and is suitable for fuel cells and water electrolysis hydrogen production.

[0038] (3) The preparation method of the present invention is simple, mild and low cost, avoiding the steps involved in commonly used methods such as highly toxic chloromethyl etherification, use of precious metal catalysts and complex polymerization, and has good prospects for industrial application. Attached Figure Description

[0039] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of the polymer solid 1 described in Example 1 of the present invention.

[0040] Figure 2 This is a thermogravimetric curve of the polymer solid 1 described in Example 1 of the present invention.

[0041] Figure 3 This is the infrared spectrum of the polymer solid 1 described in Example 1 of the present invention.

[0042] Figure 4 The infrared spectrum of the hydroxyl-type calixarene-doped anion exchange membrane 1 described in Embodiment 1 of the present invention is shown.

[0043] Figure 5 The diagram shows the antioxidant properties of the 4-tert-butylcalix[6] aromatic hydrocarbon described in Example 1 of this invention.

[0044] Figure 6 This is a schematic diagram of the mechanism. Detailed Implementation

[0045] The present invention will be further described in detail below with reference to embodiments, but the scope of the present invention is not limited by these embodiments.

[0046] Example 1

[0047] A method for preparing a composite anion exchange membrane with a rigid structure is as follows:

[0048] (1) 31.2 g (0.3 mol) styrene, 15.3 g (0.1 mol) 4-chloromethylstyrene and azobisisobutyronitrile (1 wt% of the total reactants) were dissolved in 40 mL of N,N-dimethylformamide and stirred magnetically until homogeneous. After free radical polymerization in an oil bath at 65 °C and under a nitrogen atmosphere for 20 h, the first reaction solution was obtained. The first reaction solution was slowly added dropwise to methanol to precipitate the precipitate. The precipitate was purified three times with methanol and dried in a vacuum oven at 40 °C for 24 h to obtain polymer solid 1, namely styrene-chloromethylstyrene copolymer 1.

[0049] (2) Take 0.9g of the styrene-chloromethylstyrene copolymer 1 and dissolve it in 9g of N,N-dimethylacetamide at room temperature to obtain a polymer solution with a concentration of 10wt%. Then add N-methylimidazolium and N,N,N',N'-tetramethyl-1,6-hexanediamine and react at 50℃ for 16h to carry out a nucleophilic reaction to graft imidazolium groups and quaternary ammonium groups: the molar ratio of imidazolium groups to quaternary ammonium groups is 6:4 to prepare a second reaction solution.

[0050] (3) Add 4.5 mg of 4-tert-butylcalix[6] aromatic hydrocarbon to the second reaction solution above, and stir magnetically at room temperature to prepare the third reaction solution;

[0051] (4) The above third reaction solution was cast into a film on a glass plate and dried under vacuum at 50°C for 18 h to obtain a chlorinated calixarene-doped anion exchange membrane 1.

[0052] (5) The membrane obtained above was soaked in 0.5 mol / L NaOH aqueous solution for 48 h, washed three times with deionized water until the pH of the washing solution was 7, and then vacuum dried at 40 °C for 24 h to obtain hydroxyl-type calixarene-doped anion exchange membrane 1 with a membrane thickness of 100 µm.

[0053] Example 2

[0054] (1) 31.2 g (0.3 mol) styrene, 15.3 g (0.1 mol) 4-chloromethylstyrene and azobisisobutyronitrile (0.2 wt% of total reactants) were dissolved in 50 mL of N-methylpyrrolidone and stirred magnetically. After free radical polymerization in an oil bath at 80 °C and under an argon atmosphere for 12 h, the first reaction solution was obtained. The first reaction solution was slowly added dropwise to methanol to precipitate the precipitate. The precipitate was purified three times with methanol and dried in a vacuum oven at 40 °C for 24 h to obtain polymer solid 2, namely styrene-chloromethylstyrene copolymer 2.

[0055] (2) Take 0.9g of the styrene-chloromethylstyrene copolymer 2 and dissolve it in 4.5g of N,N-dimethylformamide at room temperature to obtain a polymer solution with a concentration of 20wt%. Then add 1,2-dimethylimidazole and react at 60℃ for 10h to carry out a nucleophilic reaction to graft imidazole groups and quaternary ammonium groups: the molar ratio of imidazole groups to quaternary ammonium groups is 9:1 to prepare a second reaction solution.

[0056] (3) Add 9 mg of 4-tert-butylcalix[6] aromatic hydrocarbon to the second reaction solution above, and stir magnetically at room temperature to prepare the third reaction solution;

[0057] (4) The above third reaction solution was cast into a film on a glass plate and dried under vacuum at 60°C for 12 h to obtain chlorinated calixarene-doped anion exchange membrane 2;

[0058] (5) The membrane obtained above was soaked in 1 mol / L KOH aqueous solution for 24 h, washed three times with deionized water until the pH of the washing solution was 7, and then vacuum dried at 40 °C for 24 h to obtain hydroxyl-type calixarene-doped anion exchange membrane 2 with a membrane thickness of 110 µm.

[0059] Example 3

[0060] (1) 10.4 g (0.1 mol) styrene, 15.3 g (0.1 mol) 4-chloromethylstyrene and azobisisobutyronitrile (1 wt% of the total reactants) were dissolved in 30 mL of N,N-dimethylformamide and stirred magnetically. After free radical polymerization in an oil bath at 65°C and under a nitrogen atmosphere for 20 h, the first reaction solution was obtained. The first reaction solution was slowly added dropwise to ethanol to precipitate the precipitate. The precipitate was purified three times with ethanol and dried in a vacuum oven at 40°C for 24 h to obtain polymer solid 3, namely styrene-chloromethylstyrene copolymer 3.

[0061] (2) Take 0.9g of the styrene-chloromethylstyrene copolymer 3 and dissolve it in 9g of N,N-dimethylformamide at room temperature to obtain a polymer solution with a concentration of 10wt%. Then add 1,2-dimethylimidazole and N,N,N',N'-tetramethylethylenediamine and react at 50℃ for 16h to carry out a nucleophilic reaction to graft imidazole groups and quaternary ammonium groups: the molar ratio of imidazole groups to quaternary ammonium groups is 8:2 to prepare a second reaction solution.

[0062] (3) Add 27 mg of 4-tert-butylcalix[6] aromatic hydrocarbon to the second reaction solution above, and stir magnetically at room temperature to prepare the third reaction solution;

[0063] (4) The above third reaction solution was cast into a film on a glass plate and dried under vacuum at 50°C for 18 hours to obtain a chlorinated calixarene-doped anion exchange membrane 3.

[0064] (5) The membrane obtained above was soaked in 1 mol / L KOH aqueous solution for 24 h, washed three times with deionized water until the pH of the washing solution was 7, and then vacuum dried at 40 °C for 24 h to obtain hydroxyl-type calixarene-doped anion exchange membrane 3 with a membrane thickness of 110 µm.

[0065] Example 4

[0066] (1) 10.4 g (0.1 mol) styrene, 15.3 g (0.1 mol) 4-chloromethylstyrene and azobisisobutyronitrile (0.5 wt% of the total monomers) were dissolved in 30 mL of N,N-dimethylacetamide and stirred magnetically. After free radical polymerization in an oil bath at 70 °C and under a nitrogen atmosphere for 12 h, the first reaction solution was obtained. The first reaction solution was slowly added dropwise to methanol to precipitate the precipitate. The precipitate was purified three times with methanol and dried in a vacuum oven at 40 °C for 24 h to obtain polymer solid 4, namely styrene-chloromethylstyrene copolymer 4.

[0067] (2) Dissolve 0.9g of the styrene-chloromethylstyrene copolymer 4 in 4.5g of N,N-dimethylformamide at room temperature to obtain a polymer solution with a concentration of 20wt%. Then add N-octylimidazole and N,N,N',N'-tetramethyl-1,3-propanediamine and react at 60℃ for 12h to carry out a nucleophilic reaction to graft imidazole groups and quaternary ammonium groups: the molar ratio of imidazole groups to quaternary ammonium groups is 9:1 to prepare a second reaction solution;

[0068] (3) Add 9 mg of 4-tert-butylcalix[6] aromatic hydrocarbon to the second reaction solution above, and stir magnetically at room temperature to prepare the third reaction solution;

[0069] (4) The above third reaction solution was cast into a film on a glass plate and dried under vacuum at 60°C for 12 h to obtain a chlorinated calixarene-doped anion exchange membrane 4.

[0070] (5) The membrane obtained above was soaked in 1 mol / L NaOH aqueous solution for 24 h, washed three times with deionized water until the pH of the washing solution was 7, and then vacuum dried at 40 °C for 24 h to obtain hydroxyl-type calixarene-doped anion exchange membrane 4 with a membrane thickness of 120 µm.

[0071] Example 5

[0072] (1) 12.2 g (0.1 mol) 4-fluorostyrene, 15.3 g (0.1 mol) 4-chloromethylstyrene and azobisisobutyronitrile (0.5 wt% of the total reactants) were dissolved in 30 mL of N-methylpyrrolidone and stirred magnetically. After free radical polymerization in an oil bath at 70 °C and under a nitrogen atmosphere for 12 h, the first reaction solution was obtained. The first reaction solution was slowly added dropwise to methanol to precipitate the precipitate. The precipitate was purified three times with methanol and dried in a vacuum oven at 40 °C for 24 h to obtain polymer solid 5, namely styrene-chloromethylstyrene copolymer 5.

[0073] (2) Dissolve 0.9g of the styrene-chloromethylstyrene copolymer 4 in 4.5g of N,N-dimethylformamide at room temperature to obtain a polymer solution with a concentration of 20wt%. Then add N-octylimidazole and N,N,N',N'-tetramethyl-1,3-propanediamine and react at 60℃ for 12h to carry out a nucleophilic reaction to graft imidazole groups and quaternary ammonium groups: the molar ratio of imidazole groups to quaternary ammonium groups is 9:1 to prepare a second reaction solution.

[0074] (3) Add 9 mg of 4-tert-butylcalix[6] aromatic hydrocarbon to the second reaction solution above, and stir magnetically at room temperature to prepare the third reaction solution;

[0075] (4) The above third reaction solution was cast into a film on a glass plate and dried under vacuum at 60°C for 12 h to obtain a chlorinated calixarene-doped anion exchange membrane 5.

[0076] (5) The membrane obtained above was soaked in 0.5 mol / L KOH aqueous solution for 48 h, washed three times with deionized water until the pH of the washing solution was 7, and vacuum dried at 40 °C for 24 h to obtain hydroxyl-type calixarene-doped anion exchange membrane 5 with a membrane thickness of 110 µm.

[0077] Example 6

[0078] (1) 52.1 g (0.5 mol) styrene, 15.3 g (0.1 mol) 4-chloromethylstyrene and 2 wt% azobisisobutyronitrile (AIBN) were dissolved in 70 mL tetrahydrofuran and stirred magnetically. After free radical polymerization in an oil bath at 60 °C and under a helium atmosphere for 24 h, the first reaction solution was obtained. The first reaction solution was slowly added dropwise to methanol to precipitate the precipitate. The precipitate was purified three times with methanol and dried in a vacuum oven at 40 °C for 24 h to obtain polymer solid 6, namely styrene-chloromethylstyrene copolymer 6.

[0079] (2) Take 0.9g of the styrene-chloromethylstyrene copolymer 5 and dissolve it in 9g of N,N-dimethylformamide at room temperature to obtain a polymer solution with a concentration of 10wt%. Then add 1,2-dimethylimidazole and N,N,N',N'-tetramethyl-1,6-hexanediamine and react at 40℃ for 20h to carry out a nucleophilic reaction to graft imidazole groups and quaternary ammonium groups: the molar ratio of imidazole groups to quaternary ammonium groups is 6:4 to prepare a second reaction solution.

[0080] (3) Add 9 mg of 4-tert-butylcalix[6] aromatic hydrocarbon to the second reaction solution above, and stir magnetically at room temperature to prepare the third reaction solution;

[0081] (4) The above third reaction solution was cast into a film on a glass plate and dried under vacuum at 40°C for 24 h to obtain a chlorinated calixarene-doped anion exchange membrane 6;

[0082] (5) The membrane obtained above was soaked in 1 mol / L NaOH aqueous solution for 24 h, washed three times with deionized water until the pH of the washing solution was 7, and vacuum dried at 40 °C for 24 h to obtain hydroxyl-type calixarene-doped anion exchange membrane 6 with a membrane thickness of 80 µm.

[0083] Example 7

[0084] (1) 52.1 g (0.5 mol) styrene, 15.3 g (0.1 mol) 4-chloromethylstyrene and azobisisobutyronitrile (AIOnitrile) accounting for 1 wt% of the total reactants were dissolved in 70 mL of tetrahydrofuran and stirred magnetically until homogeneous. After free radical polymerization in an oil bath at 70 °C and under a nitrogen atmosphere for 24 h, the first reaction solution was obtained. The first reaction solution was slowly added dropwise to methanol to precipitate the precipitate. The precipitate was purified three times with methanol and dried in a vacuum oven at 40 °C for 24 h to obtain polymer solid 7, namely styrene-chloromethylstyrene copolymer 7.

[0085] (2) Take 0.9g of the styrene-chloromethylstyrene copolymer 6 and dissolve it in 3g of N,N-dimethylformamide at room temperature to obtain a polymer solution with a concentration of 30wt%. Then add N-cyclohexylimidazole and react at 60℃ for 10h to carry out a nucleophilic reaction to graft imidazole groups and quaternary ammonium groups: the molar ratio of imidazole groups to quaternary ammonium groups is 9:1 to prepare a second reaction solution.

[0086] (3) Add 45 mg of 4-tert-butylcalix[6] aromatic hydrocarbon to the second reaction solution above, and stir magnetically at room temperature to prepare the third reaction solution;

[0087] (4) The above third reaction solution was cast into a film on a glass plate and dried under vacuum at 60°C for 12 h to obtain a chlorinated calixarene-doped anion exchange membrane 7.

[0088] (5) The membrane obtained above was soaked in 1 mol / L NaOH aqueous solution for 24 h, washed three times with deionized water until the pH of the washing solution was 7, and then vacuum dried at 40 °C for 24 h to obtain hydroxyl-type calixarene-doped anion exchange membrane 7 with a membrane thickness of 90 µm.

[0089] Comparative Example 1 (without the addition of 4-tert-butylcalix[6] aromatics compared to Example 1)

[0090] (1) 31.2 g (0.3 mol) styrene, 15.3 g (0.1 mol) 4-chloromethylstyrene and azobisisobutyronitrile (1 wt% of the total reactants) were dissolved in 40 mL of N,N-dimethylformamide and stirred magnetically. After free radical polymerization in an oil bath at 65 °C and under a nitrogen atmosphere for 20 h, the first reaction solution was obtained. The first reaction solution was slowly added dropwise to methanol to precipitate the precipitate. The precipitate was purified three times with methanol and dried in a vacuum oven at 40 °C for 24 h to obtain polymer solid 1, namely styrene-chloromethylstyrene copolymer 1.

[0091] (2) Dissolve 0.9g of the styrene-chloromethylstyrene copolymer 1 in 9g of N,N-dimethylacetamide at room temperature to obtain a polymer solution with a concentration of 10wt%. Then add N-methylimidazolium and N,N,N',N'-tetramethyl-1,6-hexanediamine and carry out a nucleophilic reaction at 50°C to graft imidazolium groups and quaternary ammonium groups: the molar ratio of imidazolium groups to quaternary ammonium groups is 6:4 to prepare a second reaction solution.

[0092] (3) Add 0 mg of 4-tert-butylcalix[6] aromatic hydrocarbon to the second reaction solution above, and stir magnetically at room temperature to prepare the third reaction solution;

[0093] (4) The above third reaction solution was cast onto a glass plate to form a film, and dried under vacuum at 50°C for 18 hours to obtain a chloride anion exchange membrane 7;

[0094] (5) The membrane obtained above was soaked in 0.5 mol / L NaOH aqueous solution for 48 h, washed three times with deionized water until the pH of the washing solution was 7, and vacuum dried at 40 °C for 24 h to obtain hydrogen-oxygen anion exchange membrane 7 with a membrane thickness of 100 µm.

[0095] Comparative Example 2 (without the addition of 4-tert-butylcalix[6] aromatics compared to Example 2)

[0096] (1) 31.2 g (0.3 mol) styrene, 15.3 g (0.1 mol) 4-chloromethylstyrene and azobisisobutyronitrile (0.2 wt% of total reactants) were dissolved in 50 mL of N-methylpyrrolidone and stirred magnetically. After free radical polymerization in an oil bath at 80 °C and under an argon atmosphere for 12 h, the first reaction solution was obtained. The first reaction solution was slowly added dropwise to methanol to precipitate the precipitate. The precipitate was purified three times with methanol and dried in a vacuum oven at 40 °C for 24 h to obtain polymer solid 2, namely styrene-chloromethylstyrene copolymer 2.

[0097] (2) Take 0.9 g of the styrene-chloromethylstyrene copolymer 2 and dissolve it in 4.5 g of N,N-dimethylformamide at room temperature to obtain a polymer solution with a concentration of 20wt%. Then add 1,2-dimethylimidazole and carry out a nucleophilic reaction at 60°C to graft imidazole groups and quaternary ammonium groups: the molar ratio of imidazole groups to quaternary ammonium groups is 9:1 to prepare a second reaction solution.

[0098] (3) Add 0 mg of 4-tert-butylcalix[6] aromatic hydrocarbon to the second reaction solution above, and stir magnetically at room temperature to prepare the third reaction solution;

[0099] (4) The above third reaction solution was cast into a film on a glass plate and dried under vacuum at 60°C for 12 hours to obtain a chloride anion exchange membrane 8;

[0100] (5) The membrane obtained above was soaked in 1 mol / L KOH aqueous solution for 24 h, washed three times with deionized water until the pH of the washing solution was 7, and vacuum dried at 40 °C for 24 h to obtain hydrogen-oxygen anion exchange membrane 8 with a membrane thickness of 110 µm.

[0101] The membranes prepared in Examples 1-7 and Comparative Examples 1-2 were tested using the following methods:

[0102] (1) Nuclear magnetic resonance spectroscopy determination

[0103] The synthesis of the polymer was determined by 1H NMR spectra recorded using a nuclear magnetic resonance spectrometer (Bruker AVANCE Ⅲ HD 400 MHz, Switzerland), with deuterated dimethyl sulfoxide (DMSO) as the solvent.

[0104] (2) Thermogravimetric analysis test

[0105] The thermal stability of the samples was determined using a thermogravimetric analyzer (TGA / DSC 1100 SF, Switzerland) under a nitrogen atmosphere. The nitrogen flow rate was set to 50 mL / min, the temperature range was 40 ~ 600℃, and the linear heating rate was 20℃ / min.

[0106] (3) Infrared spectroscopy test

[0107] The chemical structures of polymer and membrane samples were characterized using an attenuated total reflectance Fourier transform infrared spectrometer (ATR-FTIR, Nicolet 6700, USA), with a resolution of 4 cm⁻¹. -1 Simultaneously, images of 4000-650cm were obtained using transmission mode. -1 Absorption spectra within the wavenumber range.

[0108] (4) DPPH free radical scavenging test

[0109] 4-tert-butylcalix[6] ethanol solutions with concentrations of 0, 0.875 μg / mL, 1.75 μg / mL, 3.5 μg / mL, 7 μg / mL, 14 μg / mL, 28 μg / mL, and 56 μg / mL were prepared. 4 mL of each concentration solution was added to 4 mL of freshly prepared DPPH ethanol solution (0.1 mM), shaken thoroughly, and reacted in the dark for 30 min. The absorbance at 517 nm of the DPPH ethanol solution (A0) without 4-tert-butylcalix[6] ethanol (Ai) and the DPPH ethanol mixture containing 4-tert-butylcalix[6] ethanol (Ai) was recorded using a dual-beam UV-Vis spectrophotometer (TU-1950, China). The test was performed three times, and the average value was taken.

[0110] HO clearance rate is calculated using the following formula:

[0111] (5) Ionic conductivity test

[0112] The ionic conductivity of the membrane was tested using an electrochemical workstation under the following conditions: temperature 80℃ and relative humidity 100%.

[0113] (6) Accelerated oxidation test

[0114] The chemical stability of the membrane was tested using a Fenton experiment to simulate an environment rich in hydroxyl radicals (HO·). The membrane sample was immersed in a pre-prepared Fenton solution (3 wt% H₂O₂, 8 ppm Fe). 2+ In the test, the temperature was 40℃. After soaking for 72 hours, the film was taken out, washed several times with deionized water, and vacuum dried at 60℃ for 24 hours. The quality of the dry film was recorded.

[0115] (7) Alkali stability test

[0116] The membrane was immersed in a 2 mol / L NaOH aqueous solution at 60℃ for 1000 h. Its initial and final conductivity were measured, and the alkali resistance stability of the membrane was evaluated by the conductivity retention rate.

[0117] Table 1. Ionic conductivity, accelerated oxidation test, and alkaline stability test data of the membranes from Examples 1-7 and Comparative Examples 1-2.

[0118]

[0119] Compared with commonly used polyether matrix materials, the polymer backbone synthesized in this invention does not contain heteroatoms such as N, O, and S. By eliminating the nucleophilic attack sites of hydroxyl (OH⁻), the risk of backbone degradation is significantly reduced. Test results show that the membranes described in Examples 1-7 and Comparative Examples 1-2 all have good alkaline stability. Compared with Comparative Examples 1-2, the ionic conductivity and chemical stability of the membranes described in Examples 1-7 are significantly improved. This is mainly attributed to the introduction of the functional additive 4-tert-butylcalix[6]arene. Its rigid cavity structure can increase the free volume inside the polymer membrane and reduce the ion migration barrier. At the same time, the macrocyclic steric phenolic structure gives it the characteristics of anti-oxidative degradation, which improves the ionic conductivity and chemical stability.

Claims

1. A high performance, high chemical stability composite anion exchange membrane containing a rigid structure, characterized in that, The composite anion exchange membrane, with a thickness of 80-120 µm, is prepared by using a synthesized polymer as a base material, ionization treatment and addition of a calixarene as a functional additive; wherein the calixarene is added in an amount of 0.5-5 wt% of the dry weight of the polymer, and the calixarene is 4-tert-butyl calix[6]arene.

2. The method of claim 1, wherein the method of preparing a high performance, high chemical stability composite anion exchange membrane having a rigid structure is characterized by, The method comprises the following steps: S1: co-dissolve a reaction monomer 1, a reaction monomer 2 and an initiator in an organic solvent, stir uniformly, and perform a free radical polymerization reaction under an inert atmosphere to obtain a first reaction solution; drop the first reaction solution into a precipitant to precipitate a precipitate; wash and dry the precipitate to obtain a polymer solid; S2: dissolve the polymer solid obtained in step S1 in a polar solvent under room temperature conditions to obtain a polymer solution, perform a functionalization reaction to graft imidazole groups and quaternary ammonium groups, and the molar ratio of the imidazole groups to the quaternary ammonium groups is a:b, wherein a and b are both integers of 1-9 and a+b=10, to obtain a second reaction solution; S3: introduce a functional additive into the second reaction solution obtained in step S2, stir uniformly, and obtain a third reaction solution, wherein the amount of the functional additive accounts for 0.5-5 wt% of the dry weight of the polymer in the second reaction solution; S4: form a film of the third reaction solution obtained in step S3 on a substrate, and obtain a chloro-type composite anion exchange membrane after drying; S5: immerse the chloro-type composite anion exchange membrane obtained in step S4 in an alkali solution at room temperature for a period of time, wash with deionized water until the pH value of the washing liquid is 7, and obtain a hydrogen-type composite anion exchange membrane after drying.

3. The preparation method according to claim 2, characterized in that, The reaction monomer 1 in step S1 is one of the compounds shown in formula (I), the reaction monomer 2 is 4-chloromethylstyrene, and the molar ratio of the reaction monomer 1 to the reaction monomer 2 is 1-5:

1. 。 4. The production method according to claim 2, characterized by, The initiator in step S1 is azobisisoheptyl nitrile, azobisisobutylonitrile, N, N-dimethylacetamide or azobiscyclohexyl nitrile, and the amount of the initiator accounts for 0.2-2 wt% of the total mass of the reaction monomers.

5. The preparation method according to claim 2, characterized in that, The organic solvent in step S1 is tetrahydrofuran, N-methylpyrrolidone, N, N-dimethylformamide or dimethyl sulfoxide, the inert atmosphere in step S1 is nitrogen, argon or helium, the free radical polymerization reaction temperature in step S1 is 60-80°C, the free radical polymerization reaction time is 12-24 h, and the precipitant in step S1 is deionized water, methanol, ethanol or isopropanol.

6. The preparation method according to claim 2, characterized in that, The polar solvent in step S2 is N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide or dimethyl sulfoxide, the concentration of the polymer solution in step S2 is 10-30 wt%, the functionalization reaction temperature in step S2 is 40-60°C, and the functionalization reaction time in step S2 is 10-20 h.

7. The preparation method according to claim 2, characterized in that, The imidazole group in step S2 is selected from one of N-methyl imidazole, N-octyl imidazole, N-cyclohexyl imidazole, 1,2-dimethyl imidazole; the quaternary ammonium group is selected from one of N, N, N', N'-tetramethyl ethylenediamine, N, N, N', N'-tetramethyl-1,3-propanediamine, N, N, N', N'-tetramethyl-1, 6-hexanediamine; the molar amount of a+b is equal to the molar amount of the monomer 2 in step S1.

8. The preparation method according to claim 2, characterized in that, The functional additive in step S3 is 4-tert-butyl calix[6]arene; the film forming method in step S4 is blade coating, casting or pouring; the base in the base solution in step S5 is KOH or NaOH, and the concentration is 0.5 mol / L to 1 mol / L; the soaking time is 24 to 48 hours.

9. The preparation method according to claim 2, characterized in that, The drying conditions in step S1, step S4 and step S5 are all vacuum drying at 40 to 60℃; the vacuum drying time is 12 to 24 hours.

10. The high-performance, chemically stable composite anion exchange membrane with rigid structure prepared according to any one of claims 1 to 9 is applied to the field of fuel cells and water electrolysis for hydrogen production.

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