Crown ether-modified perfluorosulfonic acid resin, method for producing the same, and ion exchange membrane

Abstract

This application discloses a crown ether modified perfluorosulfonic acid resin, its preparation method, its application, and an ion exchange membrane. The main chain of the crown ether modified perfluorosulfonic acid resin is a perfluorocarbon chain. The crown ether modified perfluorosulfonic acid resin includes repeating unit A, which is shown in formula (1): Formula (1); In formula (1), R0 is a crown ether group, a is a positive integer from 0 to 6, and b is a positive integer from 2 to 5. This application can effectively improve the persistence of the ion exchange membrane's free radical quenching effect, while also improving the oxygen resistance of the ion exchange membrane.

Description

Technical Field

[0001] This application relates to the technical field of polymer compounds, and in particular to a crown ether modified perfluorosulfonic acid resin, its preparation method and application, and an ion exchange membrane. Background Technology

[0002] Combining free radical quenchers with perfluorosulfonic acid resins to form ion exchange membranes can effectively improve the free radical resistance of ion exchange membranes. However, current free radical quenchers suffer from problems such as easy loss, short duration of action, or poor oxidation resistance, and urgently need improvement. Summary of the Invention

[0003] To improve the durability of the free radical quenching effect of ion exchange membranes while also enhancing their oxygen resistance, this application provides a crown ether modified perfluorosulfonic acid resin, its preparation method, its application, and an ion exchange membrane.

[0004] In one aspect, embodiments of this application provide a crown ether modified perfluorosulfonic acid resin.

[0005] The main chain of the crown ether modified perfluorosulfonic acid resin is a perfluorocarbon chain, and the crown ether modified perfluorosulfonic acid resin includes repeating unit A, which is shown in formula (1): Equation (1); In formula (1), R0 is a crown ether group, a is a positive integer from 0 to 6, and b is a positive integer from 2 to 5. For example, a can be a positive integer such as 0, 1, 3, or 5, and b can be a positive integer such as 2, 4, or 5.

[0006] Secondly, embodiments of this application provide a method for preparing crown ether modified perfluorosulfonic acid resin.

[0007] A method for preparing a crown ether modified perfluorosulfonic acid resin includes the following steps: The sulfonyl halide resin is subjected to a nucleophilic substitution reaction with a crown ether functionalizing agent, followed by post-treatment to obtain the crown ether modified perfluorosulfonic acid resin; wherein, the crown ether modified perfluorosulfonic acid resin includes a repeating unit A, which is shown in formula (1): Equation (1); In formula (1), R0 is a group containing a crown ether, a is a positive integer from 0 to 6, and b is a positive integer from 2 to 5. For example, a can be a positive integer such as 0, 1, 3, or 5, and b can be a positive integer such as 2, 4, or 5.

[0008] Thirdly, embodiments of this application provide an ion exchange membrane.

[0009] The ion exchange membrane includes crown ether modified perfluorosulfonic acid resin as mentioned in the first aspect, or crown ether modified perfluorosulfonic acid resin prepared by the preparation method mentioned in the first aspect.

[0010] Fourthly, embodiments of this application provide an application of crown ether modified perfluorosulfonic acid resin.

[0011] An application of a crown ether modified perfluorosulfonic acid resin, wherein the crown ether modified perfluorosulfonic acid resin is used in at least one of the following: proton exchange membrane for fuel cells, flow battery separator, polyelectrolyte separator for chlor-alkali industry, proton exchange membrane for hydrogen production by water electrolysis, separator for acidic primary batteries, polyelectrolyte for lithium batteries, polyelectrolyte in supercapacitors, and electrodialysis membrane for metal recovery.

[0012] Compared with the prior art, the beneficial effects of this application are as follows: This application grafts crown ether groups onto the side chain end groups of repeating unit A. The introduction of these crown ether groups endows the crown ether-modified perfluorosulfonic acid resin with excellent free radical quenching properties, reducing the possibility of degradation of the material under free radical action, thereby effectively improving the material's free radical resistance. At the same time, the main chain of the crown ether-modified perfluorosulfonic acid resin of this application has a perfluorocarbon chain structure, which makes the crown ether-modified perfluorosulfonic acid resin have excellent oxidation resistance, good stability, and is not prone to aging, which is beneficial to extending the service life of the material. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 The infrared spectrum is that of crown ether modified perfluorosulfonic acid resin CE-PFSA-2 of Example 2 disclosed in this application.

[0015] Figure 2 This is a comparison of the single-cell polarization curves of the ion exchange membrane PEM-3 of Application Example 3 and the ion exchange membrane D-PEM-3A of Comparative Example 4 after 1 hour of treatment with Fenton's reagent. Detailed Implementation

[0016] The technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] There are various types of free radical quenchers, such as small organic molecule free radical quenchers and metal oxide free radical quenchers. Among them, small organic molecule free radical quenchers have high activity, but they are prone to loss and have a short duration of action. Metal oxide free radical quenchers are difficult to disperse uniformly in mainstream ion exchange resins (such as perfluorosulfonic acid resins), which leads to a significant reduction in the mechanical and electrochemical properties of the formed ion exchange membrane.

[0018] Related studies have disclosed some organic polymer free radical quenchers, but most of the molecular chains of organic polymer free radical quenchers contain double bonds, phenyl groups, etc., which have poor oxygen resistance and limit the further improvement of the mechanical properties of ion exchange membranes.

[0019] Therefore, in order to improve the persistence of the free radical quenching effect of ion exchange membranes while also improving their oxygen resistance, this application provides a crown ether modified perfluorosulfonic acid resin, its preparation method, its application, and an ion exchange membrane. The technical solution of this application will be further described below with reference to embodiments and accompanying drawings.

[0020] In one aspect, embodiments of this application provide a crown ether modified perfluorosulfonic acid resin.

[0021] The main chain of the crown ether modified perfluorosulfonic acid resin is a perfluorocarbon chain. The crown ether modified perfluorosulfonic acid resin includes repeating unit A, which is shown in formula (1): Equation (1); In formula (1), R0 is a crown ether group, a is a positive integer from 0 to 6, and b is a positive integer from 2 to 5. For example, a can be a positive integer such as 0, 1, 3, or 5, and b can be a positive integer such as 2, 4, or 5.

[0022] The crown ether modified perfluorosulfonic acid resin provided in this application has a high molecular skeleton structure, which can effectively overcome the defects of easy migration and easy loss of traditional small molecule free radical quenchers compared with traditional small molecule free radical quenchers.

[0023] Furthermore, in terms of molecular structure design, this application grafts crown ether groups onto the side chain end groups of repeating unit A. The introduction of these crown ether groups endows the crown ether-modified perfluorosulfonic acid resin with excellent free radical quenching properties, reducing the possibility of degradation of the material under free radical action, thereby effectively improving the material's free radical resistance. At the same time, the main chain of the crown ether-modified perfluorosulfonic acid resin of this application has a perfluorocarbon chain structure and does not contain groups containing double bonds or phenyl groups. This makes the crown ether-modified perfluorosulfonic acid resin have excellent oxidation resistance, good stability, and is not prone to aging, which is beneficial to extending the service life of the material.

[0024] Furthermore, the structure of the crown ether-modified perfluorosulfonic acid resin in this application is highly similar to that of the mainstream ion exchange resin material—perfluorosulfonic acid resin—with minimal overall structural differences. This results in excellent compatibility between the crown ether-modified perfluorosulfonic acid resin and the perfluorosulfonic acid resin. When the crown ether-modified perfluorosulfonic acid resin and the perfluorosulfonic acid resin are mixed as ion exchange membrane materials, the crown ether-modified perfluorosulfonic acid resin can achieve uniform and stable dispersion with the perfluorosulfonic acid resin, effectively reducing phase separation or interface defects caused by poor compatibility. This not only effectively reduces the adverse effects of the introduction of crown ether groups on the mechanical properties of the aforementioned ion exchange membrane, but also facilitates the long-term fixation of the crown ether-modified perfluorosulfonic acid resin, making it less prone to migration or removal from the ion exchange membrane. This significantly improves the long-term operational stability of the aforementioned ion exchange membrane and substantially reduces the rate of mass decay of the membrane module.

[0025] In some embodiments, the crown ether modified perfluorosulfonic acid resin further includes repeating unit B and repeating unit C, where repeating unit B is shown in equation (2) and repeating unit C is shown in equation (3): Equation (2), Equation (3); In formula (3), M is any one of hydrogen, lithium, sodium, and potassium; The functional groups of the crown ether modified perfluorosulfonic acid resin include sulfonate groups and crown ether groups. The total mass of sulfonate groups and crown ether groups is 100%, and the mass percentage of crown ether groups is greater than or equal to 0.1%.

[0026] Repeating units B and C represent the repeating unit structures of the unmodified perfluorosulfonic acid resin. A structural comparison before and after crown ether modification reveals that the crown ether group replaces some of the side chain end groups of repeating unit C in the perfluorosulfonic acid resin, transforming the sulfonate group into a sulfonyl group, which then bonds to the crown ether group.

[0027] After modification with crown ether groups, the mass percentage of the crown ether groups is greater than or equal to 0.1%, which ensures that the resulting crown ether-modified perfluorosulfonic acid resin has a sufficient density of free radical trapping sites. For example, the mass percentage of the crown ether groups is 0.1%, 1%, 7%, 10%, 20%, 30%, 50%, etc.

[0028] Furthermore, based on the total mass of sulfonate and crown ether groups, the mass percentage of crown ether groups is preferably greater than or equal to 1%, more preferably greater than or equal to 10%. The higher the proportion of crown ether groups, the higher the grafting rate of crown ether groups, and the better the free radical quenching effect on improving the material.

[0029] In some embodiments, the total content of sulfonate and crown ether groups is 0.5 mmol / g to 3 mmol / g.

[0030] The total content of functional groups composed of sulfonate and crown ether groups is set between 0.5 mmol / g and 3 mmol / g, which can better balance the mechanical and processing properties of crown ether modified perfluorosulfonic acid resin. This ensures that the material has sufficient ion exchange capacity and crown ether grafting space, while maintaining good film-forming mechanical strength and solvent resistance, which is beneficial for industrial applications.

[0031] When the total content of functional groups composed of sulfonate and crown ether groups is less than 0.5 mmol / g, the proportion of tetrafluoroethylene repeating units in the polymer backbone is too high. This not only reduces the ion exchange capacity of the material, but also gradually makes its processing performance similar to that of polytetrafluoroethylene (PTFE), increasing the material's solubility and processing difficulty. When the total content of functional groups composed of sulfonate and crown ether groups is less than 3 mmol / g, the proportion of tetrafluoroethylene repeating units in the polymer backbone is too low, reducing the upper limit of the material's crystallinity and significantly decreasing its water solubility resistance and mechanical strength. For example, the total content of sulfonate and crown ether groups can be 0.5 mmol / g, 1 mmol / g, 1.5 mmol / g, 2 mmol / g, 2.5 mmol / g, or 3 mmol / g, etc.

[0032] Furthermore, the structural formula of the crown ether modified perfluorosulfonic acid resin is shown in formula (4): Equation (4); In formula (4), x takes the value of 3 to 8, and the sum of z1 and z2 is 1; the weight-average molecular weight of crown ether modified perfluorosulfonic acid resin is 50 kDa to 2000 kDa.

[0033] In the embodiments of this application, the left and right order of CF2 and CF in the main chain structure of the crown ether modified perfluorosulfonic acid resin can be interchanged, depending on the matrix resin structure of the synthesized crown ether modified perfluorosulfonic acid resin. This application does not make specific limitations on this.

[0034] In some embodiments, R0 is selected from at least one of amino-substituted crown ethers or azacrown ethers, wherein the structure of the amino-substituted crown ether includes the following formula (5) and formula (6), and the structure of the azacrown ether includes the following formula (7): Equation (5), Equation (6) Equation (7); Wherein, R3 is selected from C1-C12 alkylene groups or directly bonded, and R1, R2 and R4 are each independently selected from at least one of formulas (8) to (9): Equation (8) Equation (9); Among them, d, e and f are each independently selected from positive integers from 0 to 6.

[0035] It should be noted that the wavy lines in the various structural formulas of this application are... "" indicates the connection site in the structural formula, that is, the position where the structural formula is connected to other molecular segments by covalent bonds.

[0036] This application selects an amino-substituted crown ether or an aza-crown ether as the linking group RO to the sulfonyl group of the crown ether-modified perfluorosulfonic acid resin side chain. This is because amino or nitrogen atoms have high reactivity as nucleophiles, and the amino-substituted crown ether or aza-crown ether can undergo an efficient nucleophilic substitution reaction with the sulfonyl halide group on the end group of the perfluorosulfonic acid resin side chain, thereby achieving a stable connection between the crown ether group and the sulfonyl group.

[0037] In some embodiments, R0 having an amino-substituted crown ether is selected from at least one of the following formulas (10) to (13): Equation (10) Equation (11) Equation (12) Equation (13); R0, which has an azacrown ether, is selected from at least one of the following formulas (14) to (17): Equation (14) Equation (15) Equation (16) Equation (17).

[0038] Secondly, embodiments of this application provide a method for preparing crown ether modified perfluorosulfonic acid resin.

[0039] A method for preparing a crown ether modified perfluorosulfonic acid resin includes the following steps: The sulfonyl halide resin is subjected to a nucleophilic substitution reaction with a crown ether functionalizing agent, followed by post-treatment to obtain a crown ether modified perfluorosulfonic acid resin; wherein, the crown ether modified perfluorosulfonic acid resin includes a repeating unit A, which is shown in formula (1): Equation (1); In formula (1), R0 is a group containing a crown ether, a is a positive integer from 0 to 6, and b is a positive integer from 2 to 5. For example, a can be a positive integer such as 0, 1, 3, or 5, and b can be a positive integer such as 2, 4, or 5.

[0040] This application provides a reaction pathway for preparing crown ether-modified perfluorosulfonic acid resins. By using a sulfonyl halide resin as a precursor, the high reactivity of the sulfonyl halide groups at the end of the sulfonyl halide resin side chains is utilized to nucleophilically substitute with a crown ether functionalizing agent, thereby obtaining the crown ether-modified perfluorosulfonic acid resin. This reaction has the advantages of high efficiency and good controllability.

[0041] By controlling the conditions of the nucleophilic substitution reaction, the grafting rate of the crown ether group can be effectively regulated, thereby preparing crown ether-modified perfluorosulfonic acid resins with crown ether groups of different mass percentages to meet the differentiated requirements of various application scenarios for ion exchange capacity and free radical quenching effect.

[0042] In some embodiments, the halogen group in the sulfonyl halide resin includes at least one of F, Cl, Br, and I. Preferably, the halogen group in the sulfonyl halide resin includes F and Cl, that is, the sulfonyl halide resin includes at least one of sulfonyl fluoride resin or sulfonyl chloride resin; more preferably, the sulfonyl halide resin is a sulfonyl fluoride resin.

[0043] In some embodiments, the crown ether functionalizing agent includes an amino-substituted crown ether and an aza crown ether, wherein the amino-substituted crown ether includes the following formula (5) and formula (6), and the aza crown ether has the following structure (7): Equation (5), Equation (6) Equation (7); Wherein, R3 is selected from C1-C12 alkylene groups or directly bonded, and R1, R2 and R4 are each independently selected from at least one of formulas (8) to (9): Equation (8) Equation (9); Among them, d, e and f are each independently selected from positive integers from 0 to 6.

[0044] Further, the crown ether functionalizing agent is selected from at least one of the following compounds: aza-12-crown ether-4, aza-15-crown ether-5, aza-18-crown ether-6, aza-21-crown ether-7, aza-24-crown ether-8, 4'-aminobenzo-15-crown-5-ether, 4'-aminobenzo-18-crown-6-ether, 4'-aminobenzo-21-crown-7-ether, 4'-aminobenzo... -24-crown-8-ether, 2-aminomethyl-12-crown-4, 2-aminomethyl-15-crown-5, 2-aminomethyl-18-crown-6, 2-aminoethyl-15-crown-5, 2-aminopropyl-15-crown-5, 2-aminoisopropyl-15-crown-5, 4',4''(5'')-diaminodibenzo-15-crown ether-5 and 4'-aminodibenzo-18-crown-6.

[0045] Preferably, the crown ether functionalizing agent is selected from at least one of the following compounds: aza-12-crown ether-4, aza-15-crown ether-5, aza-18-crown ether-6, 2-aminomethyl-15-crown-5, 2-aminomethyl-18-crown-6, 4'-aminobenzo-15-crown-5-ether, 4'-aminobenzo-18-crown-6-ether, 4',4''(5'')-diaminodibenzo-15-crown ether-5, and 4'-aminodibenzo-18-crown-6. These crown ether functionalizing agents have good reactivity and are readily available, off-the-shelf products.

[0046] Furthermore, the crown ether functionalizing agent is selected from at least one of the following compounds: aza-12-crown ether-4, aza-15-crown ether-5, aza-18-crown ether-6, and 4'-aminobenzo-15-crown ether-5. These crown ether functionalizing agents exhibit excellent reactivity and can more effectively improve the grafting rate of crown ether groups.

[0047] In some embodiments, an organic base and a first organic medium are added to the nucleophilic substitution reaction of sulfonyl halide resin and crown ether functionalizing agent, and the reaction is carried out at 50°C to 180°C for 1 h to 120 h. The first organic medium can swell the sulfonyl halide resin, open the dense structure of the sulfonyl halide resin, and allow the crown ether functionalizing agent and organic base to penetrate into the interior of the sulfonyl halide resin, which significantly improves the contact area and grafting uniformity of the reaction.

[0048] To further promote the nucleophilic substitution reaction between sulfonyl halide resins and crown ether functionalizing agents, the sulfonyl halide resins and crown ether functionalizing agents can be reacted under specific pressures, ranging from 0.1 MPa to 10 MPa.

[0049] Furthermore, the reaction temperature for the nucleophilic substitution reaction is 60℃~150℃, and even further, it is 80℃~120℃. The reaction temperature does not exceed the boiling points of the first organic medium, the crown ether functionalizing agent, and the organic base, and reflux condensation can be used to allow the reaction system to react at a higher temperature. Increasing the reaction temperature can accelerate the reaction rate and reduce the reaction time. Preferably, the reaction time is 12 h~96 h. Furthermore, the reaction temperature can be increased by increasing the reaction pressure. Exemplarily, the reaction temperature for the nucleophilic substitution reaction can be 50℃, 60℃, 80℃, 100℃, 120℃, 150℃, 180℃, etc., and the reaction time can be 1 h, 10 h, 30 h, 50 h, 80 h, 100 h, or 120 h, etc.

[0050] In some embodiments, the mass ratio of sulfonyl halide resin, crown ether functionalizing agent, and organic base is 100:(1~400):(1~600). Exemplarily, the mass ratio of sulfonyl halide resin, crown ether functionalizing agent, and organic base can be 100:20:50, 100:50:80, 100:100:100, 100:200:300, etc. Controlling the mass ratio of sulfonyl halide resin, crown ether functionalizing agent, and organic base within the above range is beneficial for controlling the grafting rate of the crown ether group. Preferably, the mass ratio of sulfonyl halide resin, crown ether functionalizing agent, and organic base is 100:(10~250):(10~500), more preferably, the mass ratio of sulfonyl halide resin, crown ether functionalizing agent, and organic base is 100:(30~200):(30~400).

[0051] In some embodiments, the mass ratio of the sulfonyl halide resin to the first organic medium is 1:(3~30). Exemplarily, the mass ratio of the sulfonyl halide resin to the first organic medium can be 1:3, 1:10, 1:20, 1:30, etc. Controlling the mass ratio of the sulfonyl halide resin to the first organic medium within a specific range is beneficial for the swelling and dispersion of the sulfonyl halide resin, while avoiding excessive dilution of the concentration of the crown ether functionalizing agent and the organic base, thus facilitating the nucleophilic substitution reaction. Further, the mass ratio of the sulfonyl halide resin to the first organic medium is 1:(4~25), and even further, the mass ratio is 1:(5~20).

[0052] In some embodiments, the organic base includes a first organic amine and / or a second organic amine. The first organic amine includes a C1-C20 alkyl and / or a C6-C20 aryl-substituted organic amine that does not contain a nitrogen-containing heterocycle. The second organic amine includes at least one of a C1-C20 alkyl and / or a C6-C20 aryl-substituted pyridine, imidazole, pyrrole, piperidine, or piperazine. Preferably, the organic base is a tertiary amine. Tertiary amines, as organic bases, can more effectively improve the reaction efficiency between sulfonyl halide resins and crown ether functionalizing agents. Tertiary amines include triethylamine, tripropylamine, triisopropylamine, tributylamine, tripentylamine, trihexylamine, triphenylamine, dodecylamine, octadecylamine, N,N-dimethylcyclohexylamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N-dibutylethylenediamine, N,N-dimethylhexylamine, triethylethylenediamine, tetramethylethylenediamine, tetramethyl-1,3-propanediamine, tetramethyl-1,6-hexanediamine, 2,5-dimethyl-p-phenylenediamine, N,N'-dibutylphenylenediamine, and N,N-dimethyldipropyltriamine. More preferably, the tertiary amine is selected from at least one of triethylamine, tripropylamine, or tributylamine.

[0053] In some embodiments, the first organic medium is selected from at least one of acetonitrile, toluene, xylene, carbitol, dioxane, cyclohexane, hexafluorobenzene, decafluorobiphenyl, hexafluoropropylene trimer, pentafluorophenol, perfluoromethyl decahydronaphthalene, or tetrahydrofuran. Sulfonyl halide resins exhibit better swelling performance in the aforementioned first organic medium, which facilitates the nucleophilic substitution reaction.

[0054] Furthermore, the first organic medium is preferably selected from at least one of acetonitrile, cyclohexane, dioxane, hexafluorobenzene, decafluorobiphenyl, or hexafluoropropylene trimer; in this preferred first organic medium, the swelling effect of the sulfonyl halide resin is enhanced, which is more favorable for nucleophilic substitution reactions.

[0055] Furthermore, the first organic medium is preferably at least one of acetonitrile, cyclohexane, dioxane, or hexafluorobenzene. Among these further preferred first organic media, sulfonyl halide resins exhibit excellent swelling properties, further promoting the nucleophilic substitution reaction.

[0056] In some embodiments, the post-processing includes placing the first crude product swelling obtained by the nucleophilic substitution reaction in an alkaline solution to convert unreacted sulfonyl halide groups in the first crude product swelling to sulfonate groups, thereby obtaining a second crude product solid. The alkaline solution is selected from sodium hydroxide solution or potassium hydroxide solution, and the mass concentration of inorganic base in the alkaline solution is greater than or equal to 4%.

[0057] The second crude product solid is acidified with an acid solution, and then water or a second organic medium is used to remove the acid solution residue and impurities in the second crude product after acidification to obtain the third crude product solid. The acidification treatment is carried out at 20℃~100℃ for 1 h~48 h. The acid solution is selected from at least one of sulfuric acid solution, nitric acid solution, phosphoric acid solution or hydrochloric acid solution, and the concentration of inorganic acid in the acid solution is greater than or equal to 5%.

[0058] Crown ether modified perfluorosulfonic acid resin is hydrophilic. In order to suppress the excessive dissolution of crown ether modified perfluorosulfonic acid resin in alkaline solution in the first crude product swelling product, this application sets the mass concentration of inorganic alkali in the alkaline solution to be greater than or equal to 4%. In this way, the excessive dissolution of crown ether modified perfluorosulfonic acid resin can be suppressed through the common ion effect between crown ether modified perfluorosulfonic acid resin and alkaline solution, while converting unreacted sulfonyl halide groups into sulfonate groups.

[0059] Similarly, in order to suppress the excessive dissolution of crown ether modified perfluorosulfonic acid resin in the second crude product solid in the acid solution, this application sets the mass concentration of inorganic acid in the acid solution to be greater than or equal to 5%. In this way, the excessive dissolution of crown ether modified perfluorosulfonic acid resin can be suppressed through the common ion effect between crown ether modified perfluorosulfonic acid resin and acid solution, while the metal ions in crown ether modified perfluorosulfonic acid resin are replaced with hydrogen ions, and the acidification is sufficient.

[0060] The second organic medium is selected from fatty alcohols, lipids, fatty acids, ketones, and tetrahydrofuran. Further, the second organic medium is selected from at least one of methanol, ethanol, isopropanol, n-propanol, formic acid, acetic acid, ethyl acetate, acetone, butanone, methyl isobutyl ketone, cyclohexanone, isophorone, diacetone, and tetrahydrofuran. These components can effectively remove acid solution residues and impurities from the second crude product. Further, the second organic medium is selected from at least one of ethanol, isopropanol, n-propanol, acetone, or butanone. Selecting these components makes the cleaning of the second organic medium more efficient. Even further, the second organic medium is selected from acetone or butanone. Acetone and butanone are poor solvents for crown ether modified perfluorosulfonic acid resins, do not readily dissolve the product, and have good miscibility with hydrochloric acid solution, enabling efficient product purification.

[0061] Furthermore, water can dissolve some products with a high total functional group content. In the step of acidifying the second crude product solid with an acid solution, water is generally suitable for products with relatively low water solubility (total functional group content below 0.8 mmol / L) to suppress dissolution. Mixing water with ketone solvents (such as acetone, butanone, etc.) can improve the cleaning efficiency of the acid solution; preferably, the water content in the mixed solvent is less than 30% by mass. This reduces the risk of dissolution of the second crude product solid while efficiently cleaning away acid and impurities.

[0062] In some embodiments, the third crude product solid is dispersed in water and / or a third organic medium, and insoluble matter is removed by filtration to obtain a crown ether-modified perfluorosulfonic acid resin solution. Water, the third organic medium, or a mixture of water and the third organic medium can all be used as solvents to dissolve and disperse the third crude product solid, thereby forming the crown ether-modified perfluorosulfonic acid resin solution. Removing the insoluble matter can further remove impurities from the third crude product solid, resulting in a relatively pure crown ether-modified perfluorosulfonic acid resin solution.

[0063] In some embodiments, the third organic medium is selected from at least one of fatty alcohols, fatty acids, ethylene glycol, propylene glycol, glycerol, N,N-dimethylformamide, dimethyl sulfoxide, N,N-dimethylacetamide, tetramethyl sulfoxide, tetrahydrofuran, hexamethylphosphoric triamine, and N-methylpyrrolidone; these components can all dissolve crown ether modified perfluorosulfonic acid resin well, which is beneficial for forming a crown ether modified perfluorosulfonic acid resin solution with better solubility.

[0064] Furthermore, the third organic medium is selected from at least one of methanol, ethanol, n-propanol, isopropanol, n-hexanol, formic acid, acetic acid, N,N-dimethylformamide, dimethyl sulfoxide, N,N-dimethylacetamide, tetrahydrofuran, or N-methylpyrrolidone. Even further, the third organic medium is selected from at least one of n-hexane, cyclohexane, acetone, or butanone. n-Hexane, cyclohexane, acetone, or butanone possess good solubility and are easily dried and volatilized, making them the preferred third organic medium. High-boiling-point solvents such as polyols and N-methylpyrrolidone can also fully dissolve crown ether-modified perfluorosulfonic acid resins, but their excessively high boiling points make drying the solution difficult. Fatty acids such as formic acid and acetic acid have strong adsorption in crown ether-modified perfluorosulfonic acid resins, which also increases the difficulty of drying.

[0065] In some embodiments, the crown ether modified perfluorosulfonic acid resin solution is directly dried, or the crown ether modified perfluorosulfonic acid resin solution is precipitated in a poor solvent and then dried to obtain crown ether modified perfluorosulfonic acid resin. In industrial production, the crown ether-modified perfluorosulfonic acid resin solution can be directly dried to form an ion exchange membrane. Alternatively, the crown ether-modified perfluorosulfonic acid resin solution can be placed in a poor solvent to precipitate and then dried to obtain a solid state of crown ether-modified perfluorosulfonic acid resin, which facilitates its storage.

[0066] Furthermore, the unsuitable solvent is selected from at least one of lipids, aromatic hydrocarbons, alkanes, ketones, and halogenated hydrocarbons; specifically, it can be selected from at least one of ethyl acetate, toluene, n-hexane, n-pentane, cyclohexane, acetone, butanone, and dichloromethane. Since aromatic hydrocarbons and halogenated hydrocarbons are highly toxic, and lipid solvents are easily hydrolyzed into fatty acids and fatty alcohols by the acidic action of fluorinated polymers, the unsuitable solvent in this application can be selected from at least one of n-hexane, cyclohexane, acetone, or butanone. Acetone and butanone have good miscibility with water and also with a third organic medium, making them more preferred unsuitable solvents; although n-hexane and cyclohexane have poor miscibility with water and highly polar organic solvents, their polarity differs greatly from that of crown ether modified perfluorosulfonic acid resin, resulting in good precipitation. Furthermore, to address the problem of poor miscibility, ketones, halogenated hydrocarbons, aromatic hydrocarbons, and alkanes can be mixed as unsuitable solvents.

[0067] Furthermore, in the step of placing the crown ether modified perfluorosulfonic acid resin solution in a poor solvent, the volume of the poor solvent is 2 to 5 times that of the crown ether modified perfluorosulfonic acid resin solution, and the drying treatment method includes freeze drying, forced air drying or vacuum drying.

[0068] Thirdly, embodiments of this application provide an ion exchange membrane.

[0069] The ion exchange membrane includes crown ether modified perfluorosulfonic acid resin as mentioned in the first aspect, or crown ether modified perfluorosulfonic acid resin prepared by the preparation method mentioned in the first aspect.

[0070] In this application, the crown ether groups in the crown ether-modified perfluorosulfonic acid resin have a free radical quenching effect, which can effectively improve the free radical resistance of the ion exchange membrane, thereby improving the chemical durability of the ion exchange membrane. The ion exchange membrane of this application is suitable for fuel cell ion exchange membranes, water electrolysis ion exchange membranes, and flow battery separators.

[0071] In some embodiments, the ion exchange membrane further includes a perfluorosulfonic acid resin blended with a crown ether modified perfluorosulfonic acid resin.

[0072] Perfluorosulfonic acid resin, as a commonly used substrate for ion exchange membranes, can effectively transport ions and plays an important role in improving the ion exchange capacity of ion exchange membranes.

[0073] The structure of perfluorosulfonic acid resin is shown in formula (18): In equation (18), x takes values ​​from 3 to 8, and the sum of z1 and z2 is 1.

[0074] Crown ether-modified perfluorosulfonic acid resin can be used to make ion exchange membranes, but its cost is higher than that of perfluorosulfonic acid resin itself. Therefore, using perfluorosulfonic acid resin as the main component and adding an appropriate amount of crown ether-modified perfluorosulfonic acid resin to improve the free radical resistance of the composite is a more suitable technical solution. Furthermore, the crown ether-modified perfluorosulfonic acid resin of this application has a similar structure to perfluorosulfonic acid resin and excellent compatibility. When both are used as materials for ion exchange membranes, the mechanical property loss caused by the introduction of crown ether groups can be effectively reduced.

[0075] In some embodiments, the thickness of the ion exchange membrane is 5 μm to 450 μm, further, the thickness of the ion exchange membrane is 6 μm to 300 μm, and even further, the thickness of the ion exchange membrane is 7 μm to 200 μm. The ion exchange capacity of the ion exchange membrane is 0.1 mmol / g to 4 mmol / g, further, the ion exchange capacity of the ion exchange membrane is 0.15 mmol / g to 2.5 mmol / g, and even further, the ion exchange capacity of the ion exchange membrane is 0.2 mmol / g to 2 mmol / g.

[0076] In some embodiments, the ion exchange membrane further includes a porous reinforcing membrane, with crown ether modified perfluorosulfonic acid resin and / or perfluorosulfonic acid resin composited on the surface of the porous reinforcing membrane.

[0077] Further, the porous reinforced membrane material includes at least one of non-fluorinated polyolefins, fluorinated polymers, and aromatic polymers. Non-fluorinated polyolefins include at least one of polyethylene, polypropylene, or ethylene-propylene copolymers. Fluorinated polymers include at least one of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymers, tetrafluoroethylene-propylene copolymers, ethylene-tetrafluoroethylene copolymers, tetrafluoroethylene-hexafluoropropylene copolymers, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymers, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymers, polyvinyl fluoride, polychlorotrifluoroethylene, and ethylene-chlorotrifluoroethylene copolymers. Aromatic polymer membranes include at least one of polyaryletherketone, polysulfone, polyethersulfone, polyethersulfoneketone, polybenzimidazole, polyarylamide, polyimide, or polyetheretherketone. Preferably, the porous reinforced membrane material is polytetrafluoroethylene.

[0078] To better illustrate the ion exchange membrane, this application provides a method for preparing an ion exchange membrane, which includes the following steps: A crown ether modified perfluorosulfonic acid resin solution is formed by placing crown ether modified perfluorosulfonic acid resin in a first solvent, or a composite solution is formed by dispersing crown ether modified perfluorosulfonic acid resin and perfluorosulfonic acid resin together in a second solvent. The solutions are then molded and dried to obtain an ion exchange membrane.

[0079] The ion exchange membrane obtained through the above-mentioned molding and drying process has good flatness, uniform thickness distribution, and excellent performance. Furthermore, the process for preparing the ion exchange membrane in this application is simple, easy to operate, and has high production efficiency, making it suitable for widespread application in industrial production.

[0080] The solution formed by placing the crown ether modified perfluorosulfonic acid resin of this application in a solvent can be used not only to prepare ion exchange membranes, but also to prepare coatings, hydrogels and adhesives for porous membranes such as desalination membranes and ultra / microfiltration membranes, as well as various fabrics and protective equipment such as surgical gloves, protective clothing, and sterile sheets, and has a wide range of applications.

[0081] Both the first solvent and the second solvent include at least one of water, a high-boiling-point organic solvent, tetrahydrofuran, and lower fatty alcohols. The first solvent can be the same solvent or different solvents can be selected. Further, the high-boiling-point organic solvent includes at least one of ethylene glycol, propylene glycol, glycerol, N,N-dimethylformamide, dimethyl sulfoxide, N,N-dimethylacetamide, hexamethylphosphoric triamine, and N-methylpyrrolidone; further, the lower fatty alcohol includes at least one of methanol, ethanol, isopropanol, n-propanol, and n-butanol.

[0082] In some embodiments, in the step of co-dispersing the crown ether modified perfluorosulfonic acid resin and the perfluorosulfonic acid resin in a composite solution formed by a second solvent, the dispersion temperature is 10°C to 240°C; and / or, the dispersion time is 0.1h to 24h; and / or, the dispersion pressure is atmospheric pressure to 20MPa; and / or, the dispersion method includes at least one of stirring, shaking or ultrasonication.

[0083] In some embodiments, in the step of co-dispersing the crown ether-modified perfluorosulfonic acid resin and the perfluorosulfonic acid resin in a composite solution formed by a second solvent, the crown ether-modified perfluorosulfonic acid resin and the perfluorosulfonic acid resin can be mixed in any proportion. Preferably, the mass ratio of the perfluorosulfonic acid resin to the crown ether-modified perfluorosulfonic acid resin is 0~1000:1, more preferably from 10~100:1. While the crown ether-modified perfluorosulfonic acid resin itself can be used to make ion exchange membranes, its cost is higher than that of perfluorosulfonic acid resin. Therefore, using perfluorosulfonic acid resin as the main component and adding an appropriate amount of crown ether-modified perfluorosulfonic acid resin to form a composite solution to improve the free radical resistance of the ion exchange membrane is a more suitable technical solution.

[0084] In some embodiments, the molding process includes at least one of casting, pouring, or coating. The drying temperature is 20°C to 180°C. Exemplarily, the drying temperature can be 20°C, 50°C, 80°C, 100°C, 150°C, 180°C, etc.

[0085] In some embodiments, the molding process further includes coating molding, in which a crown ether modified perfluorosulfonic acid resin solution or a composite solution is coated onto one or both sides of the reinforcing membrane, and then dried to obtain an ion exchange membrane. Preferably, the coating includes at least one of impregnation, blade coating, and slot coating.

[0086] Fourthly, embodiments of this application provide an application of crown ether modified perfluorosulfonic acid resin.

[0087] An application of crown ether-modified perfluorosulfonic acid resin is disclosed. This crown ether-modified perfluorosulfonic acid resin is used in at least one of the following fields: batteries, chlor-alkali industry, water electrolysis for hydrogen production, capacitors, electrodialysis, sensors, desalination membranes, ultrafiltration membranes, microfiltration membranes, fabrics, and protective equipment. Crown ether-modified perfluorosulfonic acid resin or ion exchange membranes have broad application prospects in fields such as batteries and the chlor-alkali industry.

[0088] Specifically, the crown ether modified perfluorosulfonic acid resin of this application can be used in at least one of the following: proton exchange membranes for fuel cells, flow battery membranes, polyelectrolyte membranes for the chlor-alkali industry, proton exchange membranes for hydrogen production by water electrolysis, primary battery membranes for acid batteries, polyelectrolytes for lithium batteries, polyelectrolytes in supercapacitors, and electrodialysis membranes for metal recovery.

[0089] The technical solution of this application will be further described below with reference to more specific embodiments.

[0090] Example 1 This application provides a crown ether modified perfluorosulfonic acid resin, the preparation method of which includes the following steps: Weigh 5g of sulfonyl fluoride resin 1 and swell it in a mixed solvent of 10mL acetonitrile and 40mL hexafluorobenzene. Add 1g of aza-12-crown ether-4 and stir to disperse. Then add 12mL of triethylamine dropwise at 20℃. Subsequently, transfer the reaction system to a pressure reactor. Under a nitrogen atmosphere, raise the temperature to 80℃, the reaction pressure is 1MPa, and stir for 48h. After the reaction is completed, the mixture is cooled to below 20°C, the pressure inside the pressure reactor is removed, and the first crude product swelling is filtered out. The first crude product swelling is added to an 8 mol / L potassium hydroxide solution and reacted at 60°C for 24 h to obtain the second crude product solid. The second crude product solid was filtered out and poured into a 4 mol / L hydrochloric acid solution for acidification at a temperature of 30°C for 24 hours. The acidified second crude product solid was then washed with acetone until the washing solution was neutral to obtain the third crude product solid. The washed third crude product solid was dissolved in 70 mL of a water-alcohol mixture (water, ethanol, and isopropanol in a mass ratio of 1:1:2). The insoluble matter was removed by filtration to obtain a crown ether modified perfluorosulfonic acid resin solution. The crown ether modified perfluorosulfonic acid resin solution was poured into 250 mL of acetone cooled in an ice bath to obtain a crown ether modified perfluorosulfonic acid resin solid precipitate. The precipitate was dried under vacuum at 45 °C for 48 h to obtain a clean crown ether modified perfluorosulfonic acid resin solid CE-PFSA-1. In Example 1, the sulfonyl fluoride resin used had a weight-average molecular weight of 642 kDa and the following structure: ; The grafting rate of CE-PFSA-1 is 40%, and its structural formula is: Example 2 This application provides a crown ether modified perfluorosulfonic acid resin, the preparation method of which includes the following steps: Weigh 10g of sulfonyl fluoride resin 1 from Example 1 and swell it in 100mL of hexafluorobenzene and 20mL of dioxane mixed solvent. Add 1g of 4'-aminobenzo-15-crown ether-5 and stir to mix. Then add 20mL of triethylamine and heat to 80℃ and stir to react for 24h. After the reaction was completed, the first crude product swelling was filtered out. The first crude product swelling was added to a 4 mol / L sodium hydroxide solution and reacted at 80°C for 48 h to obtain the second crude product solid. The second crude product solid was acidified in a 2 mol / L sulfuric acid solution at a temperature of 60°C for 24 hours. The acidified second crude product solid was then washed with butanone until the washing solution was neutral to obtain the third crude product solid. The washed third crude product solid was dissolved in 90 mL of DMSO, and the insoluble matter was removed by filtration to obtain a crown ether modified perfluorosulfonic acid resin solution. 10 mL of crown ether modified perfluorosulfonic acid resin solution was cast into an ultra-flat culture dish, dried at 80 °C for 24 h, and vacuum heat-treated at 120 °C for 15 min to obtain an ion exchange membrane PEM-150 with an average thickness of 150 μm and an IEC of 1.05 mmol / g.

[0091] The remaining ionic polymer solution was poured into 300 mL of a poor solvent (dichloromethane, n-hexane, and cyclohexane in a mass ratio of 1:1:2) to obtain a crown ether modified perfluorosulfonic acid resin solid precipitate. The solid precipitate was dried under vacuum at 45 °C for 72 h to obtain a clean crown ether modified perfluorosulfonic acid resin solid CE-PFSA-2 with a grafting rate of 5%.

[0092] The structural formula of CE-PFSA-2 is as follows: Example 3 This application provides a crown ether modified perfluorosulfonic acid resin, the preparation method of which includes the following steps: Add 20 mL of dioxane to the flask, then add 1 g of sulfonyl fluoride resin 2, stir and mix at 50 °C for 2 h to allow sulfonyl fluoride resin 2 to fully swell, add 1 g of aza-15-crown ether-5 and stir to disperse, add 6 mL of triethylamine dropwise at 20 °C, raise the temperature to 80 °C and stir to react for 48 h. After the reaction was completed, the first crude product swelling was filtered out and added to a 4 mol / L sodium hydroxide solution. The mixture was reacted at 80°C for 48 h to obtain the second crude product solid. The second crude product solid was added to a 6 mol / L hydrochloric acid solution for acidification at a temperature of 60°C for 24 hours. The acidified second crude product solid was then washed with water until the washing solution was neutral to obtain the third crude product solid. The washed third crude product solid was dissolved in 20 mL of DMSO, and the insoluble matter was removed by filtration to obtain a crown ether modified perfluorosulfonic acid resin solution. The solution was poured into 100 mL of a poor solvent (dichloromethane and acetone in a mass ratio of 1:1) to obtain a crown ether modified perfluorosulfonic acid resin solid precipitate. The precipitate was dried under vacuum at 45 °C for 72 h to obtain a clean crown ether modified perfluorosulfonic acid resin solid CE-PFSA-3. The grafting rate of CE-PFSA-3 was 98%.

[0093] Among them, sulfonyl fluoride resin 2 has a weight-average molecular weight of 780 kDa and its structure is as follows: ; The structural formula of CE-PFSA-3 is as follows: Example 4 This application provides a crown ether modified perfluorosulfonic acid resin, which differs from Example 3 in that: in the step of reacting sulfonyl fluoride resin 2 with aza-15-crown ether-5, the reaction time is 6 hours, and crown ether modified perfluorosulfonic acid resin solid CE-PFSA-4 is obtained. The grafting rate of CE-PFSA-4 is 42.5%, and the rest is consistent with Example 3.

[0094] Example 5 This application provides a crown ether modified perfluorosulfonic acid resin, which differs from Example 3 in that: in the step of reacting sulfonyl fluoride resin 2 with aza-15-crown ether-5, the reaction time is 24 hours, and crown ether modified perfluorosulfonic acid resin solid CE-PFSA-5 is obtained. The grafting rate of CE-PFSA-5 is 80%, and the rest is the same as in Example 3.

[0095] Example 6 This application provides a crown ether modified perfluorosulfonic acid resin, which differs from Example 3 in that: in the step of reacting sulfonyl fluoride resin 2 with aza-15-crown ether-5, the amount of aza-15-crown ether-5 added is 250 mg, resulting in crown ether modified perfluorosulfonic acid resin solid CE-PFSA-6, with a grafting rate of 55%, and the rest is consistent with Example 3.

[0096] Example 7 This application provides a crown ether modified perfluorosulfonic acid resin, which differs from Example 1 in that: in the reaction step of sulfonyl fluoride resin and crown ether functionalizing agent, 2g of sulfonyl fluoride resin 3 is weighed and swollen in a mixed solvent of 20mL hexafluorobenzene and 5mL dioxane, 2g of aza-18-crown ether-6 is added, and then 4mL of triethylamine is added to obtain crown ether modified perfluorosulfonic acid resin solid CE-PFSA-7. The grafting rate of CE-PFSA-7 is 85%, and the rest is consistent with Example 1.

[0097] The weight-average molecular weight of sulfonyl fluoride resin 3 is 550 kDa, and its structure is as follows: The structural formula of CE-PFSA-7 is: Application Example 1 This application provides an ion exchange membrane, the preparation method of which includes the following steps: Weigh 0.5g of CE-PFSA-1 from Example 1 and 4.5g of perfluorosulfonic acid resin 1 (the -SO2F in sulfonyl fluoride resin 1 is converted to -SO3H), dissolve and disperse them in 20g of mixed solvent (water, ethanol and n-propanol in a mass ratio of 1:2:1) at 80°C to obtain a resin dispersion, cast it in an ultra-flat petri dish, dry it at 60°C for 12h, and heat treat it at 160°C for 20min to obtain an ion exchange membrane PEM-1 with an average thickness of 50μm.

[0098] Application Example 2 This application provides an ion exchange membrane, the preparation method of which includes the following steps: Weigh 2.5g of CE-PFSA-2 and 2.5g of perfluorosulfonic acid resin 1 from Example 2, and dissolve and disperse them in 20g of a water-alcohol mixed solvent (the mass ratio of water, ethanol, n-propanol, isopropanol, and n-butanol is 2:1:1:1:1) at 60°C to obtain a resin dispersion. Coat the dispersion onto a release membrane with a doctor blade, dry it at 90°C for 10 min, and heat-treat it at 150°C for 30 min to obtain an ion exchange membrane PEM-2 with an average thickness of 50μm.

[0099] Application Example 3 This application provides an ion exchange membrane, the preparation method of which includes the following steps: Weigh 0.2g of CE-PFSA-3 from Example 3 and 9.8g of perfluorosulfonic acid resin 2 (the -SO2F in sulfonyl fluoride resin 2 is converted to -SO3H), dissolve them in 40g of water-alcohol solvent (water, ethanol and n-propanol in a mass ratio of 2:2:1), and coat them on both sides of ePTFE (average thickness 11μm, porosity 81%, average pore size 221nm) with a doctor blade. Dry at 100℃ for 15min and heat-treat at 160℃ for 15min to obtain a composite ion exchange membrane PEM-3 with an average thickness of 12μm.

[0100] Application Example 4 This application provides an ion exchange membrane, which differs from Application Example 3 in that: the CE-PFSA-4 in Example 4 is used to replace the CE-PFSA-3 in Example 3 in an equal amount to obtain a composite ion exchange membrane PEM-4 with an average thickness of 12 μm, while the rest is the same as Application Example 3.

[0101] Application Example 5 This application provides an ion exchange membrane, which differs from Application Example 3 in that: the CE-PFSA-5 in Example 5 is used to replace the CE-PFSA-3 in Example 3 in an equal amount to obtain a composite ion exchange membrane PEM-5 with an average thickness of 12 μm, while the rest remains the same as Application Example 3.

[0102] Comparative Example 1 This application provides an ion exchange membrane as a comparative example, the preparation method of which includes the following steps: 5g of perfluorosulfonic acid resin 1 was weighed and dissolved and dispersed in 20g of mixed solvent (water, ethanol and n-propanol in a mass ratio of 1:2:1) at 80℃ to obtain a resin dispersion. The resin dispersion was cast into an ultra-flat petri dish, dried at 60℃ for 12h, and heat-treated at 160℃ for 20min to obtain an ion exchange membrane D-PEM-1A with an average thickness of 50μm.

[0103] Comparative Example 2 This application provides an ion exchange membrane as a comparative example, the preparation method of which includes the following steps: 0.5g of nano-cerium oxide (particle size distribution of 20~50nm) and 4.5g of perfluorosulfonic acid resin 1 were weighed and dispersed in 20g of mixed solvent (water, ethanol and n-propanol in a mass ratio of 1:2:1) at 80℃ to obtain a dispersion. The dispersion was cast into an ultra-flat petri dish, dried at 60℃ for 12h, and heat-treated at 160℃ for 20min to obtain a solid film. Due to the uneven dispersion of inorganic matter (nano-cerium oxide) in the solid film, the film forming quality was poor, and no further performance testing was performed.

[0104] Comparative Example 3 This application provides an ion exchange membrane as a comparative example, the preparation method of which includes the following steps: 0.05 g of nano-cerium oxide (particle size distribution of 20~50 nm) and 4.95 g of perfluorosulfonic acid resin 1 were weighed and dispersed in 20 g of mixed solvent (water, ethanol and n-propanol in a mass ratio of 1:2:1) at 80 °C to obtain a dispersion. The dispersion was cast into an ultra-flat petri dish, dried at 60 °C for 12 h, and heat-treated at 160 °C for 20 min to obtain an ion exchange membrane D-PEM-1B with an average thickness of 50 μm.

[0105] Comparative Example 4 This application provides an ion exchange membrane as a comparative example, the preparation method of which includes the following steps: 10g of perfluorosulfonic acid resin 2 was weighed and dissolved in 40g of water-alcohol solvent (water, ethanol and n-propanol in a mass ratio of 2:2:1). The solution was then coated on both sides of ePTFE (average thickness 11μm, porosity 81%, average pore size 221nm). The membrane was dried at 100℃ for 15min and then heat-treated at 160℃ for 15min to obtain a composite ion exchange membrane D-PEM-3A with an average thickness of 12μm.

[0106] Comparative Example 5 This application provides an ion exchange membrane as a comparative example, the preparation method of which includes the following steps: 0.2 g of aza-18-crown ether-6 and 9.8 g of perfluorosulfonic acid resin 2 were weighed and dissolved in 40 g of water-alcohol solvent (water, ethanol and n-propanol in a mass ratio of 2:2:1). The solution was then coated on both sides of ePTFE (average thickness 11 μm, porosity 81%, average pore size 221 nm) with a doctor blade. The membrane was dried at 100 °C for 15 min and then heat-treated at 160 °C for 15 min to obtain a composite ion exchange membrane D-PEM-3B with an average thickness of 12 μm.

[0107] Experiment 1 The crown ether modified perfluorosulfonic acid resin CE-PFSA-2 prepared in Example 2 was analyzed by infrared spectroscopy, and the infrared spectrum is shown below. Figure 1 .

[0108] Figure 1 In the infrared spectrum shown, the wavenumber is 1062 cm⁻¹. -1 The nearby peaks are characteristic of SN, from Figure 1 This demonstrates that the crown ether group was successfully grafted onto the polymer side chain; wavenumber 882 cm⁻¹ -1 The peak at this location represents the out-of-plane bending vibration of the benzene ring (CH); wavenumber 1172 cm⁻¹. -1 It is a CoC asymmetric stretching vibration with a wavenumber of 2800 cm⁻¹. -1 -2950cm -1 The position represents the symmetric and asymmetric stretching vibrations of the methylene group.

[0109] Experiment 2 Performance testing of ion exchange membranes Referring to GB / T20042.3-2022 "Proton Exchange Membrane Fuel Cells - Part 3: Test Methods for Proton Exchange Membranes", the ion exchange capacity (IEC), water absorption rate, tensile strength and initial conductivity of the ion exchange membranes in each application example and comparative example were tested.

[0110] Free radical resistance test of ion exchange membranes: Ion exchange membranes were immersed in Fenton's reagent at 80℃ for certain times (1 hour, 4 hours, and 8 hours), and the mass loss and conductivity decay before and after immersion were compared. Preparation of Fenton's reagent: 0.1 mL of 0.01 mol / L Fe2+ was added dropwise to 50 mL of 3% (w / w) H2O2 solution. 2+ The solution, i.e., the prepared Fenton's reagent, should be prepared and used immediately. A smaller percentage of mass loss indicates better durability. The smaller the decrease in conductivity of the ion exchange membrane after treatment with Fenton's reagent, the better its resistance to free radicals.

[0111] Table 1 shows the test results of ion exchange capacity (IEC), water absorption rate, tensile strength, and initial conductivity for Application Example 1, Application Example 2, Comparative Example 1, and Comparative Example 3.

[0112] Table 2 shows the percentage of mass loss and conductivity of the ion exchange membranes in Application Example 1, Application Example 2, Comparative Example 1, and Comparative Example 3 after free radical resistance tests (4 hours and 8 hours, respectively). The test temperature for the free radical resistance test was 80°C and the relative humidity was 95%.

[0113] Table 1 Table 2 A comparison of the data from Application Examples 1-2 and Comparative Example 1 in Tables 1 and 2 shows that after the introduction of the crown ether group, the IEC of Application Examples 1 and 2 decreased slightly compared to that of Comparative Example 1, but remained within a suitable range above 1 mmol / g. Furthermore, the initial conductivity and the conductivity after Fenton's reagent treatment of Application Examples 1 and 2 were higher, indicating that the ion exchange membranes of Application Examples 1 and 2 had better electrochemical performance. This is because the introduction of the crown ether group alters the proton transport mechanism. During Fenton's reagent treatment, the crown ether group, as a free radical quenching group, can improve the free radical resistance of the ion exchange membrane, thereby enhancing its chemical durability. Moreover, the lower percentage of mass loss and higher conductivity both indicate that the ion exchange membrane containing the crown ether group has better chemical durability. Furthermore, the introduction of crown ether modified perfluorosulfonic acid resin also improved the tensile strength of Application Example 1 and Application Example 2. This indicates that the introduction of crown ether modified perfluorosulfonic acid resin with high compatibility with perfluorosulfonic acid resin in this application can easily enhance the entanglement of polymer chain segments, thereby improving the mechanical properties of ion exchange resin.

[0114] Furthermore, comparing the data from Comparative Example 3 in Tables 1 and 2, it can be seen that the percentage of mass loss for Application Example 1, Application Example 2, and Comparative Example 3 is similar. This is because the nano-cerium oxide in D-PEM-1B acts as a free radical quencher, improving the material's resistance to free radicals. However, while adding cerium oxide to ion exchange membranes is an effective way to improve chemical durability, cerium oxide has poor compatibility with organic polymers, limiting its addition to small amounts. Additionally, the influence of cerium ions on electrochemical performance also restricts the amount added. After blending cerium oxide with perfluorosulfonic acid resin, the tensile strength of the resulting ion exchange membrane is still lower than that of Comparative Example 1, indicating that the introduction of cerium oxide weakens the mechanical properties of the ion exchange membrane. Moreover, the IEC and conductivity of the ion exchange membrane in Comparative Example 3 are lower than those in Comparative Example 1. The initial conductivity and conductivity after Fenton reagent treatment of the ion exchange membrane in Comparative Example 3 are the lowest among the four. This is because nano-cerium oxide generates cerium ions in the strongly acidic environment of the ion exchange membrane, adversely affecting the IEC and conductivity of the ion exchange membrane.

[0115] Table 3 shows the test results of ion exchange capacity (IEC), water absorption, tensile strength, and initial conductivity for Application Example 3, Application Example 4, Application Example 5, Comparative Example 4, and Comparative Example 5.

[0116] Table 4 shows the percentage of mass loss and conductivity of the ion exchange membranes in Application Example 3, Application Example 4, Application Example 5, Comparative Example 4, and Comparative Example 5 after free radical resistance tests (4 hours and 8 hours, respectively). The test temperature for the free radical resistance test was 80°C and the relative humidity was 95%.

[0117] Table 3 Table 4 The comparison of application examples 3, 4, and 5 with comparative example 4 in Tables 3 and 4 also shows that the introduction of crown ether groups significantly improves the tensile strength, free radical resistance, and initial conductivity of ion exchange membranes. This indicates that the mechanical properties, chemical durability, and electrochemical performance of ion exchange membranes are significantly improved.

[0118] As can be seen from Comparative Example 5, the tensile strength of the ion exchange membrane prepared by mixing small molecule crown ether with perfluorosulfonic acid resin in D-PEM-3B is significantly reduced, indicating that the introduction of small molecule crown ether is not conducive to improving the mechanical properties of the ion exchange membrane.

[0119] The macroscopic mass loss exhibited by the ion exchange membrane includes the mass of the lost polymer and the mass of the crown ether small molecules. Looking at the results after Fenton's reagent treatment, after 1 hour of treatment, the percentage mass loss of the ion exchange membrane in Comparative Example 5 was lower than that in Comparative Example 4; after 8 hours, the mass losses of the two were similar. This is because small molecule crown ethers possess free radical quenching capabilities, but they are also water-soluble and have a small molecular weight, making them prone to migration and removal from the ion exchange membrane matrix. When the Fenton's reagent treatment time is short, the migration and loss of small molecule crown ethers is minimal, resulting in a low percentage of ion exchange membrane mass loss. As the Fenton's reagent treatment time increases, the migration and loss of small molecule crown ethers intensifies.

[0120] Experiment 3 After treating the ion exchange membrane PEM-3 of Application Example 3 and the ion exchange membrane D-PEM-3A of Comparative Example 4 with Fenton's reagent for 1 hour, single-cell polarization curves and hydrogen permeation currents were tested. The test methods for single-cell polarization curves and hydrogen permeation currents were in accordance with GB / T20042.5-2022 "Proton Exchange Membrane Fuel Cells - Part 5: Membrane Electrode Test Methods". Figure 2 The polarization curves of single cells for PEM-3 and D-PEM-3A after 1 hour of treatment with Fenton's reagent are shown.

[0121] from Figure 2 It can be seen that, under the conditions of 80℃ and hydrogen-air humidity (%) of 10 / 35, the membrane electrode current density prepared by PEM-3 reaches 1709 mA / cm². 2 @0.65V, which is better than D-PEM-3A's 1664 mA / cm2@0.65V, and has lower internal resistance, resulting in better single-cell performance of fuel cells.

[0122] The hydrogen permeation current (80℃, 40%RH) of PEM-3 in single-cell testing was 3.1 mA / cm. 2 D-PEM-3A has an A / cm² value of 4.3 mA / cm². 2 Hydrogen permeation current characterizes the membrane module's ability to block hydrogen and reflects the durability of the ion exchange membrane. Hydrogen permeation current test results for PEM-3 and D-PEM-3A show that PEM-3 has a lower hydrogen permeation current, demonstrating its better durability.

[0123] The technical solutions disclosed in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the technical solutions and core inventive points of the embodiments of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A crown ether modified perfluorosulfonic acid resin, characterized in that, The crown ether modified perfluorosulfonic acid resin includes repeating unit A, which is shown in formula (1): Equation (1); In the formula (1), R0 is a group containing a crown ether, a is a positive integer from 0 to 6, and b is a positive integer from 2 to 5.

2. The crown ether modified perfluorosulfonic acid resin according to claim 1, characterized in that, The crown ether modified perfluorosulfonic acid resin further includes repeating unit B and repeating unit C, wherein repeating unit B is shown in equation (2) and repeating unit C is shown in equation (3): Equation (2), Equation (3); In the formula (3), M is any one of hydrogen, lithium, sodium, and potassium; The functional groups of the crown ether modified perfluorosulfonic acid resin include sulfonate groups and crown ether groups, wherein the total mass percentage of the sulfonate groups and crown ether groups is greater than or equal to 0.1%. The total content of the sulfonate group and the crown ether group is 0.5 mmol / g to 3 mmol / g; And / or, The structural formula of the crown ether modified perfluorosulfonic acid resin is shown in formula (4): Equation (4); In formula (4), x takes the value of 3 to 8, and the sum of z1 and z2 is 1; the weight-average molecular weight of the crown ether modified perfluorosulfonic acid resin is 50 kDa to 2000 kDa.

3. The crown ether modified perfluorosulfonic acid resin according to claim 1, characterized in that, R0 is selected from at least one of amino-substituted crown ethers or azacrown ethers, wherein the structure of the amino-substituted crown ether includes the following formula (5) and formula (6), and the structure of the azacrown ether includes the following formula (7): Equation (5), Equation (6) Equation (7); Wherein, R3 is selected from C1-C12 alkylene groups or directly bonded, and R1, R2 and R4 are each independently selected from at least one of formulas (8) to (9): Equation (8) Equation (9); Among them, d, e and f are each independently selected from positive integers from 0 to 6.

4. The crown ether modified perfluorosulfonic acid resin according to claim 3, characterized in that, The R0 having the amino-substituted crown ether is selected from at least one of the following formulas (10) to (13): Equation (10) Equation (11) Equation (12) Equation (13); The R0 having the said azacrown ether is selected from at least one of the following formulas (14) to (17): Equation (14) Equation (15) Equation (16) Equation (17).

5. A method for preparing a crown ether modified perfluorosulfonic acid resin, characterized in that, Includes the following steps: The sulfonyl halide resin is subjected to a nucleophilic substitution reaction with a crown ether functionalizing agent, followed by post-treatment to obtain the crown ether modified perfluorosulfonic acid resin; wherein, the crown ether modified perfluorosulfonic acid resin includes a repeating unit A, which is shown in formula (1): Equation (1); In the formula (1), R0 is a group containing a crown ether, a is a positive integer from 0 to 6, and b is a positive integer from 2 to 5.

6. The method for preparing crown ether modified perfluorosulfonic acid resin according to claim 5, characterized in that, The halogen group in the sulfonyl halide resin includes at least one of F, Cl, Br, and I; The crown ether functionalizing agent includes amino-substituted crown ethers and azacrown ethers, wherein the amino-substituted crown ethers include the following formulas (5) and (6), and the azacrown ethers have the following formula (7): Equation (5), Equation (6) Equation (7); Wherein, R3 is selected from C1-C12 alkylene groups or directly bonded, and R1, R2 and R4 are each independently selected from at least one of formulas (8) to (9): Equation (8) Equation (9); Among them, d, e and f are each independently selected from positive integers from 0 to 6; The crown ether functionalizing agent is selected from at least one of the following compounds: aza-12-crown ether-4, aza-15-crown ether-5, aza-18-crown ether-6, aza-21-crown ether-7, aza-24-crown ether-8, 4'-aminobenzo-15-crown-5-ether, 4'-aminobenzo-18-crown-6-ether, 4'-aminobenzo-21-crown-7-ether, 4'-aminobenzo- 24-crown-8-ether, 2-aminomethyl-12-crown-4, 2-aminomethyl-15-crown-5, 2-aminomethyl-18-crown-6, 2-aminoethyl-15-crown-5, 2-aminopropyl-15-crown-5, 2-aminoisopropyl-15-crown-5, 4',4''(5'')-diaminodibenzo-15-crown ether-5 and 4'-aminodibenzo-18-crown-6.

7. The method for preparing crown ether modified perfluorosulfonic acid resin according to claim 5, characterized in that, In the nucleophilic substitution reaction of the sulfonyl halide resin with the crown ether functionalizing agent, an organic base and a first organic medium are also added, and the reaction is carried out at 50~180℃ for 1h~120h at a reaction pressure of 0.1 MPa~10 MPa. The mass ratio of the sulfonyl halide resin, the crown ether functionalizing agent, and the organic base is 100:(1~400):(1~600). The mass ratio of the sulfonyl halide resin to the first organic medium is 1:(3~30). The organic base includes a first organic amine and / or a second organic amine, wherein the first organic amine includes a C1-C20 alkyl and / or a C6-C20 aryl-substituted organic amine that does not contain a nitrogen heterocycle, and the second organic amine includes at least one of a C1-C20 alkyl and / or a C6-C20 aryl-substituted pyridine, imidazole, pyrrole, piperidine, or piperazine. The first organic medium is selected from at least one of acetonitrile, toluene, xylene, carbitol, dioxane, cyclohexane, hexafluorobenzene, decafluorobiphenyl, hexafluoropropylene trimer, pentafluorophenol, perfluoromethyl decahydronaphthalene, or tetrahydrofuran; And / or, The post-processing includes placing the first crude product swelling obtained from the nucleophilic substitution reaction in an alkaline solution to convert unreacted sulfonyl halide groups in the first crude product swelling to sulfonate groups, thereby obtaining a second crude product solid. The alkaline solution is selected from sodium hydroxide solution or potassium hydroxide solution, and the mass concentration of the inorganic base in the alkaline solution is greater than or equal to 4%. The second crude product solid is acidified with an acid solution, and then water or a second organic medium is used to remove the acid solution residue and impurities in the second crude product after acidification to obtain a third crude product solid. The acidification treatment is performed at 20°C to 100°C for 1 h to 48 h. The acid solution is selected from at least one of sulfuric acid solution, nitric acid solution, phosphoric acid solution or hydrochloric acid solution, and the concentration of inorganic acid in the acid solution is greater than or equal to 5%. The second organic medium is selected from fatty alcohols, lipids, fatty acids, ketones, tetrahydrofuran. The third crude product solid is dispersed in water and / or a third organic medium, and insoluble matter is removed by filtration to obtain a crown ether modified perfluorosulfonic acid resin solution. The third organic medium includes at least one of fatty alcohol, fatty acid, ethylene glycol, propylene glycol, glycerol, DMF, DMSO, DMAc, tetramethyl sulfoxide, tetrahydrofuran, hexamethylphosphoric triamine, and NMP. The crown ether modified perfluorosulfonic acid resin solution is directly dried, or the crown ether modified perfluorosulfonic acid resin solution is precipitated in a poor solvent and then dried to obtain the crown ether modified perfluorosulfonic acid resin. The poor solvent is selected from at least one of lipids, aromatic hydrocarbons, alkanes, ketones, and halogenated hydrocarbons. In the step of placing the crown ether modified perfluorosulfonic acid resin solution in the poor solvent, the volume of the poor solvent is 2 to 5 times that of the crown ether modified perfluorosulfonic acid resin solution. The drying method includes freeze drying, forced air drying, or vacuum drying.

8. An ion exchange membrane, characterized in that, It includes crown ether modified perfluorosulfonic acid resin as described in any one of claims 1-4, or crown ether modified perfluorosulfonic acid resin prepared by the preparation method as described in any one of claims 5-7.

9. The ion exchange membrane according to claim 8, characterized in that, The ion exchange membrane also includes a perfluorosulfonic acid resin blended with the crown ether modified perfluorosulfonic acid resin; The thickness of the ion exchange membrane is 5 μm to 450 μm, and the ion exchange capacity of the ion exchange membrane is 0.1 mmol / g to 4 mmol / g. The ion exchange membrane further includes a porous reinforcing membrane, wherein the crown ether modified perfluorosulfonic acid resin and / or the perfluorosulfonic acid resin are composited on the surface of the porous reinforcing membrane. The material of the porous reinforcing membrane includes at least one of non-fluorinated polyolefins, fluorinated polymers, and aromatic polymers. The non-fluorinated polyolefins include at least one of polyethylene, polypropylene, or ethylene-propylene copolymers. The fluorinated polymers include at least one of polytetrafluoroethylene, tetrafluoroethylene hexafluoropropylene copolymers, tetrafluoroethylene propylene copolymers, ethylene tetrafluoroethylene copolymers, tetrafluoroethylene hexafluoropropylene ethylene copolymers, polyvinylidene fluoride, vinylidene fluoride hexafluoropropylene copolymers, tetrafluoroethylene perfluoroalkyl vinyl ether copolymers, vinylidene fluoride tetrafluoroethylene hexafluoropropylene copolymers, polyvinyl fluoride, polychlorotrifluoroethylene, and ethylene chloride trifluoroethylene copolymers. The aromatic polymer membrane includes at least one of polyaryletherketone, polysulfone, polyethersulfone, polyethersulfone ketone, polybenzimidazole, polyarylamide, polyimide, or polyetheretherketone.

10. An application of a crown ether-modified perfluorosulfonic acid resin, characterized in that: The crown ether modified perfluorosulfonic acid resin is used in at least one of the following: proton exchange membranes for fuel cells, flow battery membranes, polyelectrolyte membranes for the chlor-alkali industry, proton exchange membranes for hydrogen production by water electrolysis, primary battery membranes for acid batteries, polyelectrolytes for lithium batteries, polyelectrolytes in supercapacitors, and electrodialysis membranes for metal recovery.

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