Polyarylether anion exchange membrane as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of fuel cells, and particularly relates to a polyarylether anion exchange membrane as well as a preparation method and application thereof. The branched hydrogen-bond interaction poly (diphenyl ether-isatin) anion exchange membrane is used for an alkaline anion exchange membrane fuel cell, and the ion exchange capacity, water absorption swelling, mechanical strength and other properties of the prepared membrane can be controlled by changing the grafting proportion of cationic groups and flexible side chains with hydroxyl and alkoxy. The anion exchange membrane with the ether bond in the polymer main chain is synthesized, the synthesis process is simple and efficient, the introduced branched structure can increase the free volume, so that a wider and continuous high-flux ion transmission channel is expanded, a certain hydrogen-bond interaction can be formed through the synergistic effect of hydroxyl and an alkoxy bond, and the high-flux ion transmission channel is expanded. The construction of a wider ion transmission channel is promoted, so that the microphase separation form of the membrane is improved, and the comprehensive performance of the membrane is greatly optimized.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a polyarylether-based anion exchange membrane and a preparation method and application thereof. Background Art

[0002] Among the many types of fuel cells, polymer electrolyte membrane fuel cells (PEMFCs) have been extensively researched and developed. Among these, proton exchange membrane fuel cells (PEMFCs), represented by perfluorosulfonic acid Nafion membranes, have already achieved commercial application, but their high cost has limited their further development. Anion exchange membrane fuel cells (AEMFCs) have the potential to become PEMFC alternatives due to their higher oxygen reduction efficiency, ability to use precious metal-free catalysts, and wider availability of polymer chemical raw materials.

[0003] As one of the core components of AEMFC, the anion exchange membrane (AEM) faces challenges such as insufficient conductivity and stability, hindering its commercial development. Optimizing hydroxide ion conductivity has always been a key research direction for anion exchange membranes. While increasing the ion exchange capacity (IEC) can effectively enhance ion conductivity, excessive introduction of hydrophilic groups can cause excessive swelling of the membrane, significantly reducing its mechanical strength and even directly leading to membrane rupture. Furthermore, reducing membrane thickness can, to a certain extent, reduce membrane impedance and improve ion transfer efficiency, but it also weakens the membrane's mechanical strength. Therefore, there are mutual constraints between AEM properties, and balancing the various AEM properties is a key challenge. To meet practical application needs, it is necessary to develop low-cost, simple-to-synthesize anion exchange membranes that combine high ionic conductivity, good mechanical properties, and alkaline stability. Summary of the Invention

[0004] The present invention aims to provide a polyarylether-based anion exchange membrane and its preparation method and application. The preparation method provided by the present invention is simple and convenient, and the obtained anion exchange membrane has high ionic conductivity, good mechanical properties and alkaline stability.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a polyarylether-based anion exchange membrane, comprising the following steps:

[0007] The first step is to mix diphenyl ether, 1,3,5-triphenylbenzene, isatin, an acid catalyst and a first organic solvent, and perform a super acid catalytic reaction to obtain a branched poly (diphenyl ether-isatin) skeleton;

[0008] 1-methylpiperidine, 1,6-dibromohexane and a second organic solvent are mixed for a second time to carry out a bromination reaction to obtain a piperidinium cationic group;

[0009] The branched poly(diphenyl ether-isatin) backbone, the piperidinium cationic group, 2-(2-chloroethoxyethanol), the base catalyst and the third organic solvent are mixed for a third time, and an alkylation reaction is performed to obtain a quaternized poly(diphenyl ether-isatin) polyelectrolyte;

[0010] The quaternized poly(biphenyl ether-isatin) polyelectrolyte is dissolved in a fourth organic solvent to obtain a casting solution. After the casting solution is formed into a film, the obtained film is immersed in a strong alkaline solution for ion exchange to obtain the polyarylene ether-based anion exchange membrane.

[0011] Preferably, the first organic solvent is dichloromethane;

[0012] The molar ratio of the diphenyl ether, 1,3,5-triphenylbenzene and isatin is 0.05:0.95:(1-1.3);

[0013] The acid catalyst comprises trifluoroacetic acid and trifluoromethanesulfonic acid, and the molar ratio of the trifluoroacetic acid to the trifluoromethanesulfonic acid is 1:(3-4);

[0014] The molar ratio of the total molar amount of the diphenyl ether and 1,3,5-triphenylbenzene to trifluoromethanesulfonic acid is 1:(3.4-4.5);

[0015] The temperature of the super acid catalytic reaction is 0-5° C. and the time is 2-4 hours.

[0016] Preferably, the molar ratio of 1-methylpiperidine to 1,6-dibromohexane is 1:(1.5-2);

[0017] The second organic solvent is ethyl acetate.

[0018] Preferably, the temperature of the bromination reaction is 30-50° C., and the time is 24-48 hours.

[0019] Preferably, the base catalyst is anhydrous potassium carbonate;

[0020] The third organic solvent includes at least one of dimethyl sulfoxide, N-methylpyrrolidone and N,N-dimethylformamide;

[0021] The molar ratio of the branched poly(biphenyl ether-isatin) backbone to the piperidinium cationic group is 1:1.8-2;

[0022] The molar ratio of the branched poly(biphenyl ether-isatin) skeleton to 2-(2-chloroethoxyethanol) is 1:0 to 0.2.

[0023] Preferably, the temperature of the alkylation reaction is 70-90° C.; the alkylation reaction is carried out in the dark.

[0024] Preferably, the alkylation reaction comprises dissolving the branched poly(biphenyl ether-isatin) backbone in a third organic solvent, adding a base catalyst and 2-(2-chloroethoxyethanol) to carry out a first alkylation reaction, and then adding a piperidinium cationic group to carry out a second alkylation reaction;

[0025] The time of the first alkylation reaction is shown to be 18 to 36 h;

[0026] The second alkylation reaction time is 18 to 36 hours.

[0027] Preferably, the strong alkaline solution includes at least one of a potassium hydroxide solution and a sodium hydroxide solution;

[0028] The concentration of the strong alkali solution is 1 to 4 mol / L; and the immersion time is 24 to 48 hours.

[0029] The present invention also provides a polyarylether-based anion exchange membrane prepared by the preparation method described in the above technical solution, wherein the structural formula of the polyarylether-based anion exchange membrane is shown in Formula I;

[0030]

[0031] The value range of x is 0 to 0.2.

[0032] The present invention also provides the use of the polyarylether-based anion exchange membrane described in the above technical solution in anion exchange membrane fuel cells.

[0033] The present invention provides a method for preparing a poly(arylene ether)-based anion exchange membrane. The branched hydrogen-bonding poly(biphenyl ether-isatin) anion exchange membrane of the present invention is used in alkaline anion exchange membrane fuel cells. By changing the grafting ratio of cationic groups and flexible side chains with hydroxyl groups and alkoxy groups, the ion exchange capacity, water absorption and swelling, mechanical strength and other properties of the prepared membrane can be controlled. The present invention synthesizes an anion exchange membrane containing ether bonds in the polymer backbone. The synthesis process is simple and efficient. The introduced branched structure can increase the free volume, thereby expanding a wider and continuous high-flux ion transport channel. The synergistic effect of the hydroxyl and alkoxy bonds can form a certain hydrogen bonding effect, promoting the construction of a wider ion transport channel. These all improve the microphase separation morphology of the membrane and greatly optimize the comprehensive performance of the membrane. Ultimately, the poly(arylene ether)-based anion exchange membrane obtained by the preparation method provided by the present invention has good mechanical properties and thermal stability as well as good ion conductivity and alkaline stability. In addition, the preparation method provided by the present invention has low synthesis cost, a simple and efficient process, and is easy to synthesize in large quantities. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1Schematic diagram of the synthesis of the quaternized poly(biphenyl ether-isatin) polymer provided by the present invention;

[0035] Figure 2 1H NMR spectra of the branched poly(biphenyl ether-isatin) polymer, (6-bromoalkyl)-1-methylpiperidine, and quaternized poly(biphenyl ether-isatin) polymer in Examples 1 to 3 of the present invention;

[0036] Figure 3 The infrared spectra of the exchange membranes obtained in Examples 1 to 3 of the present invention are shown;

[0037] Figure 4 The optical image, SEM plane and SEM cross-sectional image of the exchange membrane obtained in Example 2 of the present invention;

[0038] Figure 5 TEM images of the exchange membranes obtained in Examples 2 and 3 of the present invention;

[0039] Figure 6 The mechanical performance diagram of the exchange membrane obtained in Examples 1 to 3 of the present invention;

[0040] Figure 7 Thermogravimetric analysis diagrams of the exchange membranes obtained in Examples 1 to 3 of the present invention;

[0041] Figure 8 The OH of the ion exchange membrane obtained in Examples 1 to 3 of the present invention is - Ionic conductivity and Arrhenius plots;

[0042] Figure 9 The alkali resistance test diagram of the exchange membrane obtained in Examples 1 to 3 of the present invention and the alkali stability test diagram of the exchange membrane obtained in Example 3 before and after the alkali stability test are shown in FIG. 1 H NMR spectrum. DETAILED DESCRIPTION

[0043] The present invention provides a method for preparing a polyarylether-based anion exchange membrane, comprising the following steps:

[0044] The first step is to mix diphenyl ether, 1,3,5-triphenylbenzene, isatin, an acid catalyst and a first organic solvent, and perform a super acid catalytic reaction to obtain a branched poly (diphenyl ether-isatin) skeleton;

[0045] 1-methylpiperidine, 1,6-dibromohexane and a second organic solvent are mixed for a second time to carry out a bromination reaction to obtain a piperidinium cationic group;

[0046] The branched poly(diphenyl ether-isatin) backbone, the piperidinium cationic group, 2-(2-chloroethoxyethanol), the base catalyst and the third organic solvent are mixed for a third time, and an alkylation reaction is performed to obtain a quaternized poly(diphenyl ether-isatin) polyelectrolyte;

[0047] The quaternized poly(biphenyl ether-isatin) polyelectrolyte is dissolved in a fourth organic solvent to obtain a casting solution. After the casting solution is formed into a film, the obtained film is immersed in a strong alkaline solution for ion exchange to obtain the polyarylene ether-based anion exchange membrane.

[0048] The invention first mixes diphenyl ether, 1,3,5-triphenylbenzene, isatin, an acid catalyst and a first organic solvent, and performs a super acid catalytic reaction to obtain a branched poly(diphenyl ether-isatin) skeleton.

[0049] In the present invention, the first organic solvent is preferably dichloromethane; the molar ratio of the diphenyl ether, 1,3,5-triphenylbenzene and isatin is preferably 0.05:0.95:(1-1.3), specifically 0.05:0.95:1, 0.05:0.95:1.1, 0.05:0.95:1.2, 0.05:0.95:1.3; the acid catalyst preferably includes trifluoroacetic acid and trifluoromethanesulfonic acid, and the molar ratio of trifluoroacetic acid to trifluoromethanesulfonic acid is preferably 1:(3-4); the molar ratio of the total molar amount of the diphenyl ether and 1,3,5-triphenylbenzene to trifluoromethanesulfonic acid is preferably 1:(3.4-4.5), specifically 1:3.4, 1:3.5, 1:4.0, 1:4.2, 1:4.5.

[0050] In the present invention, the first mixing process is preferably: after adding diphenyl ether, isatin and 1,3,5-triphenylbenzene to the first organic solvent, the acid catalyst is slowly added dropwise; the dropping rate of the acid catalyst is preferably 0.15 to 0.3 mL / min, specifically 0.15 mL / min, 0.2 mL / min, 0.25 mL / min, and 0.3 mL / min.

[0051] In the present invention, the temperature of the super acid catalytic reaction is preferably 0-5°C, specifically 0°C, 1°C, 2°C, 3°C, 4°C, 5°C; the time is preferably 2-4h, specifically 2h, 3h, 4h.

[0052] In the present invention, after the super acid catalytic reaction, the highly viscous system is preferably subjected to post-treatment. The post-treatment preferably includes: slowly pouring the highly viscous system into anhydrous methanol to precipitate a light yellow fibrous solid, cutting the solid into small pieces and then performing five methanol hot washing purifications and three deionized water boiling neutralization treatments at 45°C, and finally drying in a 60°C oven for 24 hours.

[0053] In the present invention, 1-methylpiperidine, 1,6-dibromohexane and a second organic solvent are mixed for a second time, and a bromination reaction is performed to obtain a piperidinium cationic group.

[0054] In the present invention, the molar ratio of 1-methylpiperidine to 1,6-dibromohexane is preferably 1:(1.5-2), specifically 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2; the second organic solvent is preferably ethyl acetate.

[0055] In the present invention, the second mixing process preferably includes: mixing 1,6-dibromohexane and a second organic solvent, and then adding 1-methylpiperidine to the mixed system; the rate of the addition is preferably 0.1 to 0.3 mL / min, specifically 0.1 mL / min, 0.2 mL / min, or 0.3 mL / min. In the present invention, the temperature of the bromination reaction is preferably 30 to 50°C, specifically 30°C, 35°C, 40°C, 45°C, or 50°C; the time is preferably 24 to 48 hours, specifically 24 hours, 30 hours, 36 hours, 42 hours, or 48 hours; the bromination reaction is preferably carried out under closed conditions.

[0056] In the present invention, during the bromination reaction, the reaction system is milky white and accompanied by the generation of a white precipitate; after the bromination reaction, the obtained system is preferably subjected to post-treatment, and the post-treatment preferably comprises: separating the precipitate from the obtained system by suction filtration, washing and purifying it with ethyl acetate for five rounds, and finally rotary evaporation to obtain a white crystalline powder, which is the piperidinium cationic group.

[0057] After obtaining the branched poly(diphenyl ether-isatin) backbone and the piperidinium cationic group, the present invention thirdly mixes the branched poly(diphenyl ether-isatin) backbone, the piperidinium cationic group, 2-(2-chloroethoxyethanol), a base catalyst, and a third organic solvent to perform an alkylation reaction to obtain a quaternized poly(diphenyl ether-isatin) polyelectrolyte.

[0058] In the present invention, the base catalyst is preferably anhydrous potassium carbonate; the third organic solvent preferably includes at least one of dimethyl sulfoxide, N-methylpyrrolidone and N,N-dimethylformamide; the molar ratio of the branched poly(diphenyl ether-isatin) backbone and the piperidinium cationic group is preferably 1:1.8-2, specifically 1:1.8, 1:1.9, 1:2.0; the molar ratio of the branched poly(diphenyl ether-isatin) backbone and 2-(2-chloroethoxyethanol) is preferably 1:0-0.2, specifically 1:0 (i.e., without adding 2-(2-chloroethoxyethanol)), 1:0.1, 1:0.2.

[0059] In the present invention, the temperature of the alkylation reaction is preferably 70 to 90°C, specifically 70°C, 80°C, or 90°C, and the alkylation reaction is preferably carried out in the dark. In the present invention, the process of the alkylation reaction is preferably as follows: dissolving the branched poly(biphenyl ether-isatin) backbone in a third organic solvent, adding an alkali catalyst and 2-(2-chloroethoxyethanol) to carry out a first alkylation reaction, and then adding a piperidinium cationic group to carry out a second alkylation reaction; the time of the first alkylation reaction is preferably 18 to 36 hours, specifically 18 hours, 24 hours, 30 hours, or 36 hours; the time of the second alkylation reaction is preferably 18 to 36 hours, specifically 18 hours, 24 hours, 30 hours, or 36 hours.

[0060] In the present invention, the piperidinium cationic group is preferably added in the form of a solution, and the solvent of the solution is preferably the same as the third organic solvent. The present invention has no particular limitation on the concentration of the solution, and any concentration known to those skilled in the art can be used.

[0061] In the present invention, after the alkylation reaction, the obtained system is preferably subjected to post-treatment. The post-treatment preferably includes: centrifuging the system and precipitating it in ethyl acetate, filtering the product and washing it repeatedly with ethyl acetate twice, then repeatedly washing it with deionized water three times, and finally drying it in an oven at 60°C for 24 hours.

[0062] After obtaining the quaternized poly(biphenyl ether-isatin) polyelectrolyte, the present invention dissolves the quaternized poly(biphenyl ether-isatin) polyelectrolyte in a fourth organic solvent to obtain a casting solution. After the casting solution is formed into a film, the obtained film is immersed in a strong alkaline solution for ion exchange to obtain the polyarylene ether-based anion exchange membrane.

[0063] In the present invention, the fourth organic solvent preferably includes at least one of dimethyl sulfoxide, N-methylpyrrolidone and N,N-dimethylformamide. In the present invention, the dissolution is preferably carried out under ultrasonic conditions; after the dissolution, it is also preferably included to let the obtained solution system stand for one day. In the present invention, the amount ratio of the quaternized poly (diphenyl ether-isatin) polyelectrolyte and the fourth organic solvent in the casting solution is preferably 0.3g:15mL. In the present invention, the film forming process is preferably: the casting solution is uniformly cast on the surface of a clean glass substrate for coating to form a film, and drying; the drying method is preferably vacuum drying, the vacuum drying temperature is preferably 60°C, and the time is preferably 24h.

[0064] In the present invention, the strong alkaline solution preferably comprises at least one of potassium hydroxide solution and sodium hydroxide solution; the concentration of the strong alkaline solution is preferably 1 to 4 mol / L; the immersion temperature is preferably room temperature; and the immersion time is preferably 24 to 48 hours. In the present invention, after the ion exchange, the membrane is preferably stored in deionized water from which carbon dioxide has been removed.

[0065] The present invention also provides a polyarylether-based anion exchange membrane prepared by the preparation method described in the above technical solution, wherein the structural formula of the polyarylether-based anion exchange membrane is shown in Formula I;

[0066]

[0067] The value range of x is 0 to 0.2.

[0068] In the present invention, the value of x can be 0, 0.1, or 0.2.

[0069] The present invention also provides the use of the polyarylether-based anion exchange membrane described in the above technical solution in anion exchange membrane fuel cells.

[0070] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0071] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0072] Example 1

[0073] 1.545 g of isatin, 0.153 g of 1,3,5-triphenylbenzene, and 1.51 mL of biphenyl ether were mixed in 7 mL of dichloromethane and stirred to dissolve at 0°C. Subsequently, 0.8 mL of trifluoroacetic acid and 3.25 mL of trifluoromethanesulfonic acid were added dropwise (at a rate of 0.2 mL / min) and stirred at 0°C for 3.0 h. When the reaction system became a highly viscous solution, it was slowly poured into anhydrous methanol to precipitate a light yellow fibrous solid. The solid was cut into small pieces and purified by five methanol hot washings at 45°C and three deionized water boiling neutralization treatments. Finally, it was dried in an oven at 60°C for 24 h to obtain a branched poly(biphenyl ether isatin) polymer product, designated as TPEP.

[0074] In an eggplant-shaped flask, 9.0 mL of 1,6-dibromohexane and 50 mL of ethyl acetate were thoroughly mixed, and 4.5 mL of 1-methylpiperidine was added dropwise (at a rate of 0.15 mL / min). The closed reaction system was reacted at 40°C for 36 hours. The reaction system was observed to be milky white with the formation of a white precipitate. The precipitate was separated by filtration, washed with ethyl acetate for five rounds, and finally rotary evaporated to obtain a white crystalline powder, which was recorded as Br-Pip.

[0075] 0.3086 g of TPEP was dissolved in 12 mL of DMSO at room temperature. After a uniform solution was formed, 0.2070 g of anhydrous K2CO3 was first added to the reaction system. Subsequently, 0.5260 g of Br-Pip was dissolved in 6 mL of DMSO at room temperature and slowly added to the reaction system. The mixture was reacted in an oil bath at 80 ° C in the dark for 24 h. After the reaction was completed, the mixture was centrifuged and precipitated in ethyl acetate. The product was filtered and washed repeatedly with ethyl acetate twice, then washed repeatedly with deionized water three times, and finally dried in an oven at 60 ° C for 24 h to obtain a polymer, which was recorded as TPEP-Pip-OH-0.

[0076] 0.3 g of TPEP-Pip-OH-0 was dissolved in 15 mL of DMSO to form a uniform and transparent casting solution. After ultrasonic treatment, the solution was allowed to stand for one day, and then the casting solution was evenly cast on the surface of a clean glass substrate. The solution was then transferred to a 60°C vacuum drying oven for 24 hours of continuous drying. After the film was formed, the membrane sample was placed in a 1 mol / L KOH solution for 48 hours, and ion exchange was carried out at room temperature. Finally, the OH-form membrane was immersed in deionized water to remove carbon dioxide for use in subsequent tests. The structural formula of the exchange membrane obtained is the case where x is 0 in Formula I.

[0077] Example 2

[0078] TPEP and Br-Pip were obtained respectively according to the method of Example 1;

[0079] After 0.3086 g of TPEP was dissolved in DMSO at room temperature to form a uniform solution, 0.2070 g of anhydrous K2CO3 and 10.56 μL of 2-(2-chloroethoxyethanol) were added to the reaction system in sequence, and then the mixture was reacted in an oil bath at 80°C in the dark for 24 h. Then, 0.4734 g of Br-Pip was weighed and dissolved in 6 mL of DMSO at room temperature, and the mixture was slowly added to the reaction system. The mixture was reacted in an oil bath at 80°C in the dark for 24 h. After the reaction, the mixture was centrifuged and precipitated in ethyl acetate. The product was filtered and washed repeatedly with ethyl acetate twice, then washed repeatedly with deionized water three times, and finally dried in an oven at 60°C for 24 h to obtain a polymer, which was recorded as TPEP-Pip-OH-10.

[0080] The membrane formation and ion exchange were carried out in the manner of Example 1 to obtain an anion exchange membrane; the structural formula of the obtained exchange membrane corresponds to the case where x is 0.1 in Formula I.

[0081] Example 3

[0082] TPEP and Br-Pip were obtained respectively according to the method of Example 1;

[0083] After 0.3086 g of TPEP was dissolved in DMSO at room temperature to form a uniform solution, 0.2070 g of anhydrous K2CO3 and 21.11 μL of 2-(2-chloroethoxyethanol) were added to the reaction system in sequence, and then the mixture was reacted in an oil bath at 80°C in the dark for 24 h. Then, 0.4208 g of Br-Pip was weighed and dissolved in 6 mL of DMSO at room temperature, and the mixture was slowly added to the reaction system. The mixture was reacted in an oil bath at 80°C in the dark for 24 h. After the reaction, the mixture was centrifuged and precipitated in ethyl acetate. The product was filtered and washed repeatedly with ethyl acetate twice, then washed repeatedly with deionized water three times, and finally dried in an oven at 60°C for 24 h to obtain a polymer, which was recorded as TPEP-Pip-OH-20.

[0084] The membrane formation and ion exchange were carried out in the manner of Example 1 to obtain an anion exchange membrane; the structural formula of the obtained exchange membrane corresponds to the case where x is 0.2 in Formula I.

[0085] Comparative Example 1

[0086] 1.545 g of indigo carmine and 1.59 mL of diphenyl ether were mixed in 7 mL of dichloromethane and stirred to dissolve at 0°C. Subsequently, 0.8 mL of trifluoroacetic acid and 3.00 mL of trifluoromethanesulfonic acid (with a dropwise addition rate of 0.2 mL / min) were added dropwise and stirred at 0°C for 2.0 h. When the reaction system became a highly viscous solution, it was slowly poured into anhydrous methanol to precipitate a light yellow fibrous solid. The solid was cut into small pieces and purified by 5 methanol hot washings at 45°C and 3 deionized water boiling neutralization treatments. Finally, it was dried in a 60°C oven for 24 h to obtain a polybiphenyl ether indigo carmine polymer product, recorded as PEP.

[0087] Performance Testing

[0088] Test Example 1

[0089] The chemical structures of the samples were characterized using a Bruker AVANCE NEO 400 MHz spectrometer, with DMSO-d6 as the deuterated reagent.

[0090] Figure 2 (a) shows the TPEP polymer backbone and the PEP polymer backbone1 By comparing the H NMR spectra, it was found that the TPEP with the introduction of 1,3,5-triphenylbenzene showed a signal peak at 7.36~7.89ppm, which was attributed to the hydrogen signals H1~H3 on the benzene ring of 1,3,5-triphenylbenzene, while the PEP without the branching agent 1,3,5-triphenylbenzene showed a signal peak at 7.36~7.89ppm. 1 No characteristic peaks appeared in this range in the HNMR spectrum, which also indicated the successful introduction of 1,3,5-triphenylbenzene in TPEP. The hydrogen signals H4~H9 on the aromatic rings of diphenyl ether and isatin appeared at 6.91~7.21ppm, and the single peak at 10.77ppm was attributed to the characteristic peak of N-H on isatin.

[0091] Br-Pip 1 HNMR spectrum Figure 2 As shown in (b), 3.55 ppm corresponds to the signal peak H1 of bromine-substituted methylene, and 3.31 ppm corresponds to the signal peaks H6, H8 and H1 of methylene around the N atom on the piperidine ring. 12 , 3.01ppm corresponds to the methyl signal peak H7 connected to the N atom, 1.82ppm corresponds to the equivalent methylene signal peak H9~H on the piperidine ring 11 , 1.31~1.73ppm are attributed to the methylene signal peaks H2~H5 on the alkyl chain.

[0092] TPEP-Pip-OH-x 1 HNMR Figure 2 As shown in (c), there are several weak hydrogen signals at 7.50-7.84 ppm, indicating the hydrogen signals H1-H3 of the aromatic ring in the branching agent 1,3,5-triphenylbenzene, 6.96-7.34 ppm corresponding to the hydrogen signals H4-H9 on the aromatic ring in diphenyl ether and indigo carmine, and 3.76 ppm is attributed to the methylene signal peak H connected to the polymer main chain. 10 and H 20 , 3.27ppm corresponds to the methylene signal peak H around the N atom of the piperidine ring 15 and H 16 , 2.96ppm corresponds to the methyl hydrogen signal H attached to the N atom 16 , 1.24~1.73ppm corresponds to the remaining methylene hydrogen signals on the alkyl chain H 11 ~H 14 and the methylene hydrogen signal H on the piperidine ring 17 and H 18, 3.94ppm, 4.58ppm, which are the characteristic peaks of TPEP-Pip-OH-0, wherein 3.68ppm corresponds to methylene hydrogen signal H 21 and H 22 , 3.94ppm corresponds to methylene hydrogen signal H 23 connected with hydroxyl, 4.58ppm corresponds to the characteristic peak of hydroxyl. The above results show the successful synthesis of branched poly(biphenyl ether-indigo) polymer, (6-bromoalkyl)-1-methylpiperidine and quaternary ammonium poly(biphenyl ether-indigo) polymer.

[0093] Test Example 2

[0094] The structure of TPEP-Pip-OH-x membrane was further verified by Fourier infrared spectrum, as shown in Figure 3 , the wide peak at 3413cm -1 belongs to the hydroxyl in the membrane and water molecules, the absorption peak at 3043cm -1 corresponds to C―H stretching vibration on benzene ring, 2942cm -1 corresponds to the stretching vibration of methylene in alkyl chain, 1704cm -1 belongs to the stretching vibration of C=O group in indigo, 1604cm -1 , 1493cm -1 and 1463cm -1 belong to the stretching vibration of C=C in aromatic ring, 1294cm -1 corresponds to the stretching vibration of C―N in quaternary ammonium group, 1241cm -1 and 1174cm -1 belong to the stretching vibration of ether bond, the above results further prove the successful synthesis of TPEP-Pip-OH-x polymer membrane.

[0095] Test Example 3

[0096] The anion exchange membrane prepared in Example 2 was analyzed by scanning electron microscope, as shown in Figure 4 , it can be seen from the optical diagram that the prepared membrane is transparent and uniform as a whole, the SEM plan view and cross-sectional view show that the surface and cross-section are flat and dense, and no obvious defects are presented, through the analysis of cross-sectional morphology characterization results, the thickness of the membrane is about 24μm.

[0097] At the same time, the nanostructures of the anion exchange membranes prepared in Example 2 and Example 3 were observed using a transmission electron microscope. Figure 5 (a) and Figure 5 As shown in (b), the dark area with higher electron density represents the hydrophilic nanophase, which mainly corresponds to the hydrophilic area formed by the aggregation of cationic groups, ether bonds and hydroxyl groups. The bright area with lower electron density represents the hydrophobic nanophase, which mainly corresponds to the hydrophobic area formed by the aggregation of polymer skeleton and long hydrophobic alkyl chains. It can be seen that both TPEP-Pip-OH-10 and TPEP-Pip-OH-20 membranes show obvious hydrophilic / hydrophobic microphase separation morphology, which is beneficial to reduce the ion transport resistance and improve the ion transport efficiency. The ether bonds and hydroxyl groups in the introduced 2-(2-chloroethoxyethanol) can synergistically form a certain hydrogen bond network, further improving the microphase separation morphology. The size of the ion cluster is also affected by the concentration of the cationic group. With the increase of IEC, the size of the ion cluster will also increase accordingly. Compared with TPEP-Pip-OH-20, TPEP-Pip-OH-10 has a more significant microphase separation morphology. This is because it has a higher degree of cationic group grafting under the regulation of shared alkoxy and hydroxyl groups. This is conducive to the formation of good ion transport channels and promotes OH - Efficient transmission.

[0098] Test Example 4

[0099] Use a computer tensile testing machine at 1 mm min -1 The mechanical properties of the anion exchange membranes prepared in Examples 1 to 3 were tested under constant tension mode. Figure 6 and as shown in Table 1;

[0100] Table 1 Mechanical properties of anion exchange obtained in Example

[0101] Example Tensile strength (MPa) Elongation at break (%) TPEP-Pip-OH-0 37.89 20..50 TPEP-Pip-OH-10 43.11 18.92 TPEP-Pip-OH-20 48.15 21.36

[0102] It can be seen that with the increase in the introduction ratio of 2-(2-chloroethoxyethanol), the tensile strength shows an upward trend, and the elongation at break shows a trend of first decreasing and then increasing. Among them, the TPEP-Pip-OH-20 film has the highest tensile strength and elongation at break, reaching 48.15 MPa and 21.36%, respectively, indicating that the introduction of side chains containing ether bonds and hydroxyl groups has a positive effect on improving the tensile strength and toughness of the film.

[0103] Test Example 5

[0104] The thermal stability of the films prepared in Examples 1 to 3 of the present invention was tested using a conventional thermogravimetric analyzer in a nitrogen atmosphere. The obtained thermogravimetric analysis graphs are shown in FIG. Figure 7As shown, all membrane samples exhibited three stages of weight loss. The first stage of weight loss occurred below 110°C and was attributed to the evaporation of residual water and solvent within the membrane. The second stage occurred between 170 and 300°C, primarily due to the degradation of quaternary ammonium cationic groups and alkyl chains. The third stage occurred between 400 and 600°C, primarily due to the degradation of the TPEP polymer backbone. The three membranes exhibited slight differences in mass loss, primarily due to the varying densities of grafted cationic groups. The TPEP-Pip-OH-0 membrane, with the highest degree of functionalization, exhibited the greatest mass loss between 170 and 300°C, further demonstrating its highest cationic group density. AEMFCs typically operate at around 100°C. These results demonstrate that the TPEP-Pip-OH-x membrane degrades at temperatures well above the operating temperature of AEMFCs, demonstrating excellent thermal stability.

[0105] Test Example 6

[0106] The OH content of the membrane was tested by electrochemical impedance spectroscopy using a Zahner Zennium Pro electrochemical workstation. - Conductivity, the relationship between ionic conductivity and temperature is as follows Figure 8 As shown in (a), with the increase of temperature, the ionic conductivity shows an upward trend, which is attributed to the accelerated movement of water molecules at high temperature. At the same time, the OH- conductivity shows a trend of first increasing and then decreasing with the increase of the proportion of grafted 2-(2-chloroethoxyethanol), which is consistent with the change trend of WU and SR. Among them, TPEP-Pip-OH-10 shows the highest OH - The conductivity reached 58.0mS·cm at 30℃ -1 , when the temperature was raised to 80℃, it reached 114.0mS·cm -1 , which is higher than the TPEP-Pip-OH-0 membrane with a higher IEC value. It can be seen that the introduced alkoxy and hydroxyl side chains expand the hydrophilic area in the membrane and provide hydrogen bonding, which is conducive to accelerating the OH - The transmission of . Figure 8 (b) shows the Arrhenius curve between temperature and hydroxide conductivity. The apparent activation energy (Ea) of TPEP-Pip-OH-x membrane is between 11.89 and 14.38 kJ·mol -1 Among them, the apparent activation energy of TPEP-Pip-OH-10 membrane is the lowest, which is 11.89 kJ·mol -1 , indicating that OH - The mass transfer resistance is the lowest, which is related to the - The test results of ionic conductivity are consistent with the analysis.

[0107] Test Example 7

[0108] The TPEP-Pip-OH-x membrane was immersed in 1 mol / L KOH solution at 80℃ and the change of ionic conductivity over time was monitored. To reduce the influence of carbon dioxide in the air, the alkali solution was replaced every certain period of time. Figure 9 As shown in (a), after 384 hours of alkali treatment, the ion conductivity of several membranes decreased rapidly. With the increase of alkali treatment time, the downward trend gradually slowed down. Finally, after 1000 hours of alkali resistance test, the ion conductivity retention rate remained above 81%, showing good alkali resistance stability. To further confirm the alkali stability of the membrane, TPEP-Pip-OH-20 was used as the membrane sample and the membrane was tested before and after alkali treatment. 1 HNMR characterization and analysis of its structural changes, such as Figure 9 As shown in (b), no chemical shift of the phenolic hydroxyl group was observed at about 6 ppm after alkali treatment, indicating that the ether-containing polymer main chain is relatively stable in an alkaline environment.

[0109] Based on the above method, the present invention synthesizes an anion exchange membrane containing an ether backbone through a superacid-catalyzed Friedel-Crafts reaction. The presence of ether bonds in the backbone not only reduces the cost of superacid-catalyzed polycondensation, but also promotes the construction of microphase separation morphology within the membrane. Through branching strategies and structural design with the introduction of flexible side chains, the hydrophilic / hydrophobic microphase separation structure within the membrane is also enhanced, and the ion conductivity at 80°C reaches 114.0 mS·cm -1 The hydrogen bonding between alkoxy and hydroxyl groups improves the mechanical properties of the membrane to a certain extent. The tensile strength and elongation at break reach 48.15 MPa and 21.36% respectively. At the same time, after 1000 hours of alkali resistance test in 1 mol / L KOH solution at 80°C, the ion conductivity retains more than 81% of the initial value. In addition, after alkali treatment, the membrane 1 The overall H NMR spectrum showed little difference, and no phenolic hydroxyl signal was observed at about 6 ppm, indicating that the ether-based anion exchange membrane had good alkaline stability and showed great application potential in the field of alkaline anion exchange membrane fuel cells.

[0110] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a polyarylether-based anion exchange membrane, characterized in that: The following steps are involved: The first step is to mix diphenyl ether, 1,3,5-triphenylbenzene, isatin, an acid catalyst and a first organic solvent, and perform a super acid catalytic reaction to obtain a branched poly (diphenyl ether-isatin) skeleton; 1-methylpiperidine, 1,6-dibromohexane and a second organic solvent are mixed for a second time to carry out a bromination reaction to obtain a piperidinium cationic group; The branched poly(diphenyl ether-isatin) backbone, the piperidinium cationic group, 2-(2-chloroethoxyethanol), the base catalyst and the third organic solvent are mixed for a third time, and an alkylation reaction is performed to obtain a quaternized poly(diphenyl ether-isatin) polyelectrolyte; The quaternized poly(biphenyl ether-isatin) polyelectrolyte is dissolved in a fourth organic solvent to obtain a casting solution. After the casting solution is formed into a film, the obtained film is immersed in a strong alkaline solution for ion exchange to obtain the polyarylene ether-based anion exchange membrane.

2. The preparation method according to claim 1, characterized in that The first organic solvent is dichloromethane; The molar ratio of the diphenyl ether, 1,3,5-triphenylbenzene and isatin is 0.05:0.95:(1-1.3); The acid catalyst comprises trifluoroacetic acid and trifluoromethanesulfonic acid, and the molar ratio of the trifluoroacetic acid to the trifluoromethanesulfonic acid is 1:(3-4); The molar ratio of the total molar amount of the diphenyl ether and 1,3,5-triphenylbenzene to trifluoromethanesulfonic acid is 1:(3.4-4.5); The temperature of the super acid catalytic reaction is 0-5° C. and the time is 2-4 hours.

3. The preparation method according to claim 1, characterized in that The molar ratio of 1-methylpiperidine to 1,6-dibromohexane is 1:(1.5-2); The second organic solvent is ethyl acetate.

4. The preparation method according to claim 1 or 3, characterized in that The temperature of the bromination reaction is 30-50° C., and the time is 24-48 hours.

5. The preparation method according to claim 1, characterized in that The base catalyst is anhydrous potassium carbonate; The third organic solvent includes at least one of dimethyl sulfoxide, N-methylpyrrolidone and N,N-dimethylformamide; The molar ratio of the branched poly(biphenyl ether-isatin) backbone to the piperidinium cationic group is 1:1.8-2; The molar ratio of the branched poly(biphenyl ether-isatin) skeleton to 2-(2-chloroethoxyethanol) is 1:0 to 0.

2.

6. The preparation method according to claim 1, characterized in that The temperature of the alkylation reaction is 70-90° C.; the alkylation reaction is carried out in the dark.

7. The preparation method according to claim 1 or 6, characterized in that The alkylation reaction process is as follows: dissolving the branched poly(biphenyl ether-isatin) backbone in a third organic solvent, adding a base catalyst and 2-(2-chloroethoxyethanol) to carry out a first alkylation reaction, and then adding a piperidinium cationic group to carry out a second alkylation reaction; The time of the first alkylation reaction is shown to be 18 to 36 h; The second alkylation reaction time is 18 to 36 hours.

8. The preparation method according to claim 1, characterized in that The strong alkaline solution includes at least one of a potassium hydroxide solution and a sodium hydroxide solution; The concentration of the strong alkali solution is 1 to 4 mol / L; and the immersion time is 24 to 48 hours.

9. The polyarylether-based anion exchange membrane prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The structural formula of the polyarylether-based anion exchange membrane is shown in Formula I; The value range of x is 0 to 0.

2.

10. Use of the polyarylene ether-based anion exchange membrane according to claim 9 in anion exchange membrane fuel cells.

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