Modified anion exchange polymer, preparation method thereof and anion exchange membrane

Abstract

The invention provides a modified anion exchange polymer, a preparation method thereof and an anion exchange membrane. In the structural general formula of the modified anion exchange polymer, R is selected from any one of C1-C20 straight-chain alkylene groups; r1, R2 and R3 are respectively and independently selected from any one of H and C1-C20 straight-chain alkyl groups. According to the modified anion exchange polymer disclosed by the invention, aryl (such as p-terphenyl) with an alkali-resistant characteristic is taken as a part of a main chain, and on the basis, on one hand, a cationic group with strong alkali resistance is introduced into the main chain of the modified anion exchange polymer, so that the cation density of the modified anion exchange polymer is increased; and the stability in a strong alkaline environment is also obviously improved. On the other hand, by introducing a side chain containing a cationic group, the ionic conductivity of the anion exchange membrane is improved, and the alkali-resistant stability of the anion exchange membrane is also enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a modified anion exchange polymer, a preparation method thereof and an anion exchange membrane. BACKGROUND

[0002] Anion exchange membranes are widely used in electrolytic cells, fuel cells, carbon dioxide reduction, hard water softening, desalinated water, pure water preparation, hydrometallurgy, rare element separation, pharmaceuticals, sugar industry, amino acid adsorption and other fields. Among them, in the field of electrolytic water hydrogen production, anion exchange membranes (AEMs) are often used to separate hydrogen between the anode and the cathode and to provide an anion transmission channel. The effective active component of the anion exchange membrane is an anion resin, which is usually composed of a polymer backbone and a charged ion-conducting group, and the polymer backbone and the ion-conducting group are connected by long or short side chains.

[0003] Although anion exchange membranes play an important role in electrochemical devices, the anion exchange membranes in the prior art still have many deficiencies in comprehensive performance. Alkali resistance stability is a key indicator for measuring the stability of anion exchange membranes in an alkaline environment. For the anion resins reported in the prior art, which have polyphenylene ether, polyarylene ether, polysulfone, polybenzimidazole as the main chain, there are defects such as large rigidity and difficulty in film formation. For example, the conventional main chain (such as polyphenylene ether, polysulfone) and cationic groups are prone to breakage and degradation in a strong alkali environment, resulting in a decrease in ion conductivity, a decrease in mechanical strength, and a decrease in dimensional stability, thereby destroying the structure of the anion exchange membrane. This alkali instability not only limits the application range of the membrane material, but also increases the maintenance cost and safety risk of the electrochemical device.

[0004] In summary, the anion exchange membranes in the prior art have many deficiencies in ion conductivity, chemical stability and other aspects, and in particular, the alkali resistance stability needs to be improved. Therefore, it is an urgent need to develop a new type of anion exchange membrane material that can not only maintain high ion conductivity, but also significantly improve alkali resistance stability and dimensional stability. SUMMARY

[0005] The main purpose of the present application is to provide a modified anion exchange polymer, a preparation method thereof and an anion exchange membrane, so as to solve the problem that the anion exchange membrane in the prior art is prone to degradation in an alkaline environment.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a modified anion exchange polymer is provided, which has the following general structure:

[0007]

[0008] Wherein, R is selected from C1 to C2. 20 Any one of the straight-chain alkylene groups; R1, R2, and R3 are each independently selected from H, C1 to C1. 20 Ar1, Ar2, and Ar3 are each selected from C4, Ar2, and Ar3, respectively, representing the molar content of their corresponding chain segments in the modified anion exchange polymer. The value of x ranges from 0 to 100, and the value of y ranges from 1 to 50, with (x+y)≤100. 12 ~C 40 Any of the aryl groups.

[0009] Furthermore, the value range of y is 5 to 50, and the value range of (x+y) is 30 to 95; and / or Ar1, Ar2, and Ar3 are each independently selected from C. 12 ~C 24 Any of the arylene groups; and / or R is selected from C1 to C2. 10 Any one of the straight-chain alkylene groups.

[0010] Furthermore, the value range of (x+y) is 70–95; and / or Ar1, Ar2, and Ar3 are each independently selected from any of the following substituents:

[0011] in Indicates the connection positions of Ar1, Ar2, and Ar3 in the modified anion exchange polymer; and / or R is selected from any one or more straight-chain alkylene groups from C1 to C8; and / or R1, R2, and R3 are each independently selected from H, C1 to C8. 10 Any one of the straight-chain alkyl groups.

[0012] Furthermore, the R mentioned above is selected from any one of methylene, ethylene, propylene, butylene, pentylene, and hexylene; and / or R1, R2, and R3 are each independently selected from any one of methyl, ethyl, propyl, butyl, pentyl, and hexyl.

[0013] According to another aspect of the present invention, a method for preparing the aforementioned modified anion exchange polymer is provided, the method comprising: step S1, polymerizing a first reactant comprising an aryl compound, a quinine cyclic ketone compound, trifluoroacetophenone and an organic acid to obtain a first intermediate polymer; step S2, reacting the first intermediate polymer with... The first substitution reaction is carried out with the second reaction raw material of the alkaline substance to obtain a first substitution reaction system; and the third reaction raw material including the first substitution reaction system and methyl iodide is used to carry out the second substitution reaction to obtain the modified anion exchange polymer; wherein X is Cl or Br; the quinuclidone compound is 3-quinuclidone hydrochloride and / or 3-quinuclidone; and the organic acid is a mixture of trifluoromethanesulfonic acid and trifluoroacetic acid.

[0014] Further, in the step S1, the molar ratio of trifluoromethanesulfonic acid to trifluoroacetic acid is 3-25:1; and / or the temperature of the polymerization reaction is -10-10°C, preferably -10-2°C; and / or the time of the polymerization reaction is 3-48h, preferably 6-24h; and / or the first reaction raw material further includes a first solvent, preferably the first solvent is selected from any one or more of dichloromethane, trichloromethane, chloroform, and tetrahydrofuran.

[0015] Further, in the step S2, the alkaline substance is selected from any one or more of potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate; and / or the second reaction raw material further includes trifluoromethanesulfonic acid and / or trifluoroacetic acid; and / or the temperature of the first substitution reaction is 60-100°C, preferably 60-80°C; and / or the time of the first substitution reaction is 1h-18h, preferably 6h-12h; and / or the second reaction raw material further includes a second solvent, preferably the second solvent is selected from any one or more of dimethyl sulfoxide and N-methyl pyrrolidone.

[0016] Further, in the step S3, the temperature of the second substitution reaction is 25-50°C, preferably 25-30°C; and / or the time of the second substitution reaction is 18h-48h, preferably 24h-30h.

[0017] According to still another aspect of the present application, there is provided an anion exchange membrane obtained by film-forming the modified anion exchange polymer, wherein the modified anion exchange polymer is the modified anion exchange polymer as described above.

[0018] Further, the tensile strength of the anion exchange membrane is 15-70MPa; and / or the ion conductivity of the anion exchange membrane at 80°C is 90-230mS / cm; and / or the ion conductivity retention rate of the anion exchange membrane after being soaked in a KOH solution at 80°C for 2000 hours is 93%-99%, wherein the concentration of the KOH solution is 1mol / L.

[0019] With the technical solution of the present application, the modified anion exchange polymer has an aryl group (such as p-terphenyl) with alkali resistance as part of the main chain. On this basis, on the one hand, by introducing a cationic group with strong alkali resistance into the main chain of the modified anion exchange polymer, the cationic density of the modified anion exchange polymer is increased, and the stability of the modified anion exchange polymer in a strong alkali environment is significantly improved. On the other hand, by introducing a side chain containing a cationic group, the ionic conductivity of the anion exchange membrane is improved, and the alkali resistance of the anion exchange membrane is enhanced. Specifically, the positive charge nitrogen atom (N + ) and the hydroxyl group (OH-) on the side chain form an ion transmission channel, and the presence of the R group enables the side chain to be closely combined with the main chain to form a continuous ion transmission network, thereby improving the ion conduction performance of the anion exchange membrane. In addition, by controlling the value range of x and y, the synergistic effect of the aryl main chain structure and the cationic group can be promoted, so that the modified anion exchange polymer can maintain structural integrity under high alkalinity conditions, reduce the degradation probability, and thereby improve the ionic conductivity of the modified anion exchange polymer, achieve a good balance, and ultimately obtain an anion exchange membrane with high alkali resistance and high ionic conductivity. BRIEF DESCRIPTION OF DRAWINGS

[0020] The drawings accompanying the specification of the present application serve to provide a further understanding of the present application, and the illustrative embodiments of the present application and their descriptions serve to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0021] Figure 1 The infrared spectrum of the modified anion exchange polymer shown in Example 1 of the present application is shown. DETAILED DESCRIPTION

[0022] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.

[0023] As analyzed in the background art of the present application, there is a problem in the prior art that an anion exchange membrane is prone to degradation in an alkaline environment. In order to solve the above problem, the present application provides a modified anion exchange polymer, a preparation method thereof, and an anion exchange membrane.

[0024] In a typical embodiment of the present application, a modified anion exchange polymer is provided, which has the following general structure:

[0025]

[0026] wherein R is selected from C1-C 20any one of linear alkyl groups of C1-C20; x, y respectively represent the molar content of the corresponding chain in the modified anion exchange polymer, the value range of x is 0-100, the value range of y is 1-50, and (x+y)≤100; Ar1, Ar2 and Ar3 are each independently selected from any one of C6-C20 20 any one of linear alkyl groups of C1-C20; x, y respectively represent the molar content of the corresponding chain in the modified anion exchange polymer, the value range of x is 0-100, the value range of y is 1-50, and (x+y)≤100; Ar1, Ar2 and Ar3 are each independently selected from any one of C6-C20 12 -C20 40 any one of arylene groups of C6-C20.

[0027] The modified anion exchange polymer of the present application takes aryl (such as p-terphenyl) with alkali resistance as part of the main chain, on this basis, on the one hand, by introducing cationic groups with strong alkali resistance into the main chain of the modified anion exchange polymer, not only the cationic density of the modified anion exchange polymer is increased, but also its stability in a strong alkaline environment is significantly improved. On the other hand, by introducing side chains containing cationic groups, not only the ionic conductivity of the anion exchange membrane is improved, but also its alkali resistance is enhanced. Specifically, the positive charge nitrogen atom (N + ) and hydroxyl group (OH-) on the side chain form an ion transport channel, and the presence of the R group enables these side chains to be closely combined with the main chain to form a continuous ion transport network, thereby improving the ion conduction performance of the anion exchange membrane. In addition, by controlling the value range of x and y, the synergistic effect of the aryl main chain structure and the cationic group can be promoted, so that the modified anion exchange polymer can maintain structural integrity under high alkalinity conditions, reduce its degradation probability, and thus improve the ionic conductivity of the modified anion exchange polymer, achieving a good balance, and ultimately obtaining an anion exchange membrane with high alkali resistance and high ionic conductivity.

[0028] In an embodiment of the present application, the value range of y is 5-50, and the value range of (x+y) is 30-95; and / or Ar1, Ar2 and Ar3 are each independently selected from any one of C6-C20 12 -C20 24 any one of arylene groups of C6-C20. 10 any one of linear alkyl groups of C1-C20.

[0029] By further optimizing the value range of y and (x+y), the distribution of functional groups in the modified anion exchange polymer is optimized, so as to achieve the best performance balance. Specifically, the value range of y represents the proportion of units containing cationic groups in the side chain in the modified anion exchange polymer. The value range of (x+y) means that the polymer has functional units, and through the synergistic control of the two value ranges, a better balance point between the ionic conductivity and the alkali resistance stability of the modified anion exchange polymer can be found, so that the modified anion exchange polymer can maintain good mechanical strength and chemical stability at the same time.

[0030] Due to the inherent alkali resistance of the arylene group, the preferred Ar1, Ar2 and Ar3 above make the main chain of the modified anion exchange polymer have higher stability in a strong alkali environment, so as to be able to resist chemical corrosion in an alkaline environment and reduce the possibility of main chain rupture or degradation. In addition, the preferred arylene group structure above can optimize the arrangement and connectivity of ion transmission channels, promote the effective conduction of ions, and improve the ionic conductivity of the anion exchange membrane. At the same time, it can also improve other physical properties of the anion exchange membrane, such as mechanical strength, flexibility and thermal stability, which makes the anion exchange membrane more durable and reliable in complex application environments.

[0031] In an embodiment of the present application, the value range of (x+y) above is 70-95; and / or Ar1, Ar2 and Ar3 are each independently selected from any one of the following substituents:

[0032] wherein indicates the connection position of Ar1, Ar2 and Ar3 in the modified anion exchange polymer; and / or R is selected from any one or more of C1-C8 linear alkylene; and / or R1, R2 and R3 are each independently selected from any one of H, C1-C8 linear alkyl. 10

[0033] The preferred (x+y) can find a better balance point between the ionic conductivity and the alkali resistance stability of the modified anion exchange polymer. The preferred Ar1, Ar2 and Ar3 above make the main chain of the modified anion exchange polymer have higher stability in a strong alkali environment.

[0034] In an embodiment of the present application, the above R is selected from any one of methylene, ethylene, propylene, butylene, pentylene, hexylene; and / or R1, R2 and R3 are each independently selected from any one of methyl, ethyl, propyl, butyl, pentyl, hexyl.

[0035] ​By the preferred selection of R, R1, R2 and R3 groups, the present application aims to optimize the physical and chemical properties of anion exchange membranes, including improving mechanical strength, optimizing ion transport efficiency, reducing membrane swelling rate, and improving wetting and durability, thereby providing more efficient, stable and durable membrane material solutions for electrochemical energy conversion and storage devices.

[0036] In another typical embodiment of the present application, a preparation method of the modified anion exchange polymer is provided, which comprises: step S1, polymerizing first reaction raw materials comprising aryl compounds, quinuclidone compounds, trifluoroacetophenone and organic acids to obtain a first intermediate polymer; step S2, performing a first substitution reaction on the first intermediate polymer and second reaction raw materials comprising a basic substance to obtain a first substitution reaction system; step S3, performing a second substitution reaction on the first substitution reaction system and third reaction raw materials comprising iodomethane to obtain the modified anion exchange polymer; wherein X is Cl or Br; the quinuclidone compound is 3-quinuclidone hydrochloride and / or 3-quinuclidone; and the organic acid is a mixture of triflic acid and trifluoroacetic acid.

[0037] Firstly, a first intermediate polymer with a main chain structure is obtained by polymerization reaction, wherein the aryl compounds provide the main chain structure of the polymer, and the quinuclidone compounds introduce cationic groups (N + ) into the polymer. The strong acidic environment (triflic acid and trifluoroacetic acid) promotes the polymerization reaction. The tetra-substituted ammonium ion and methyl are introduced into the side chain of the polymer by the first substitution reaction and the second substitution reaction, respectively, thereby not only improving the ionic conductivity of the anion exchange membrane and enhancing its alkali resistance, but also ensuring the controllability and efficiency of the preparation method of the modified anion exchange polymer.

[0038] In an embodiment of the present application, in the step S1, the molar ratio of triflic acid to trifluoroacetic acid is 3-25:1; and / or the temperature of the polymerization reaction is -10-10°C, preferably -10-2°C; and / or the time of the polymerization reaction is 3-48h, preferably 6-24h; and / or the first reaction raw materials further comprise a first solvent, preferably the first solvent is selected from any one or more of dichloromethane, trichloromethane, chloroform and tetrahydrofuran.

[0039] The preferred molar ratio of triflic acid to trifluoroacetic acid helps to further catalyze the polymerization reaction. The preferred temperature and time help to improve the efficiency and effect of the polymerization reaction. The preferred first solvent helps to the solubility of the aryl compounds, quinuclidone compounds and trifluoroacetophenone therein.

[0040] ​In an embodiment of the present application, in the step S2, the basic substance is selected from any one or more of potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate; and / or the second reaction raw material further comprises trifluoromethanesulfonic acid and / or trifluoroacetic acid; and / or the temperature of the first substitution reaction is 60-100°C, preferably 60-80°C; and / or the time of the first substitution reaction is 1h-18h, preferably 6h-12h; and / or the second reaction raw material further comprises a second solvent, preferably the second solvent is selected from any one or more of dimethyl sulfoxide and N-methyl pyrrolidone.

[0041] The preferred above basic substance creates a weakly basic environment for the first substitution reaction, thereby helping to promote the first substitution reaction while reducing the occurrence of side reactions. The preferred temperature and time help to improve the efficiency and effect of the first substitution reaction. The preferred second solvent has a dispersion effect in promoting the dispersion of the system after the first substitution reaction and iodomethane therein.

[0042] In order to further improve the efficiency and effect of the second substitution reaction, in an embodiment of the present application, in the step S3, the temperature of the second substitution reaction is 25-50°C, preferably 25-30°C; and / or the time of the second substitution reaction is 18h-48h, preferably 24h-30h.

[0043] In another typical embodiment of the present application, an anion exchange membrane is provided, which is obtained by film-forming a modified anion exchange polymer, wherein the modified anion exchange polymer is the modified anion exchange polymer described above.

[0044] The modified anion exchange polymer of the present application has an aryl main chain and a side chain containing a certain amount of cationic groups by setting its structure and functional groups, so that the anion exchange membrane obtained by the synergistic effect of the aryl main chain structure and the cationic groups has high alkali resistance and high ionic conductivity.

[0045] As can be seen from the above, the anion exchange membrane of the present application has excellent mechanical strength, high ionic conductivity, and alkali resistance, and in an embodiment of the present application, the tensile strength of the anion exchange membrane is 15-70MPa, and / or the ionic conductivity of the anion exchange membrane at 80°C is 90-230mS / cm; and / or the ionic conductivity retention rate of the anion exchange membrane after being soaked in a 1mol / L KOH solution at 80°C for 2000 hours is 93%-99%. Such an anion exchange membrane is more suitable for use in an alkaline environment, not only has a longer service life, but also has a better use effect.

[0046] The beneficial effects of the present application will be further illustrated in the following examples.

[0047] Example 1: Aryl is p-terphenyl, x = 75, y = 20

[0048] (1) Synthesis of intermediate 1: A three-necked round bottom flask equipped with a reflux condenser was charged with 1,6-dibromohexane (10 mL, 65 mmol) and tetrahydrofuran (THF, 300 mL) as solvent. In another three-necked flask, an excess of trimethylamine (TMA) aqueous solution (10 mL, 65 mmol) was heated to 50 °C, and gaseous TMA was introduced into the main reaction system by slow nitrogen purging. After 12 hours of continuous TMA gas purging, the system was kept at room temperature for another 12 hours, during which white precipitate was formed. After the reaction was completed, the white precipitate was separated by filtration. The precipitate was washed with ethyl acetate (EA) for three times to remove residual 1,6-dibromohexane. The product was dried in an oven at 80 °C for 24 hours, and finally intermediate 1 was obtained.

[0049]

[0050] (2) Synthesis of intermediate polymer: 2.3 g (10.0 mmol) of p-terphenyl was weighed into a 100 mL three-necked flask, and 1.53 g (9.5 mmol) of 3-quinuclidinone hydrochloride and 0.087 g of trifluoromethyl phenyl ketone (0.5 mmol) were added. The reaction was dissolved in 10 mL of dichloromethane. 12 mL of triflic acid and 1 mL of trifluoroacetic acid (molar ratio of triflic acid to trifluoroacetic acid is 10:1) were added at 0 °C, and the reaction was stirred for 6 hours. The viscous purple product was poured into a 1 mol / L K2CO3 solution, soaked at room temperature for 24 hours, and filtered to obtain a white solid product. After washing with deionized water, the product was dried to obtain the intermediate polymer.

[0051] (3) Synthesis of functionalized polymer: 1 g of the above intermediate polymer was weighed into a 100 mL single-necked flask, 15 mL of dimethyl sulfoxide was added, and 150 μL of trifluoroacetic acid was added to promote polymer dissolution. After complete dissolution, 0.36 g of potassium carbonate, 0.186 g of intermediate 1, and 60 °C were added, and the reaction was carried out for 16 hours. Then 300 μL of iodomethane was added, and the reaction was carried out at room temperature for 24 hours. The reaction product was poured into ethyl acetate to precipitate a white precipitate, which was washed several times with ethyl acetate and then with water and dried to obtain a functionalized polymer with I- as anion. Its infrared spectrum is shown in Figure 1 -1 wherein the wave peak at 2910 cm -1 represents -CH2-, indicating that the intermediate 1 segment is contained in the anion exchange polymer molecular chain. The wave peak at 1230 cm -1 represents C-F bond, and the wave peak at 1360 cm -1 ​The peak at 1600 cm"1represents the carbon-carbon bond on the benzene ring, which indicates that the aryl backbone segment is contained in the molecular chain of the anion exchange polymer.

[0052] (4) Film formation, crosslinking and ion exchange: 1 g of the modified anion exchange polymer described above was weighed, 50 mL of dimethyl sulfoxide was added, and after being dissolved thoroughly, it was poured into the groove of a flat glass plate, and dried at 80°C for 48 hours to form a film. After the film was peeled off from the glass plate, it was immersed in a 1 mol / L KOH solution, and ion exchanged at room temperature for 48 hours to obtain an anion exchange membrane with OH - as the anion.

[0053] Example 2: aryl group is p-terphenyl, x = 10, y = 20

[0054] (1) Synthesis of intermediate 1: A three-necked round-bottom flask equipped with a reflux condenser was charged with 1,6-dibromohexane (10 mL, 65 mmol) and tetrahydrofuran (THF, 300 mL) as the solvent. In another three-necked flask, an excess of aqueous trimethylamine (TMA) solution (10 mL, 65 mmol) was heated to 50°C, and gaseous TMA was introduced into the main reaction system by slow nitrogen blowing. After 12 hours of continuous TMA gas blowing, the system was kept at room temperature for another 12 hours of reaction, during which white precipitate was generated. After the reaction was completed, the white precipitate was separated by filtration. The precipitate was washed with ethyl acetate (EA) three times to remove residual 1,6-dibromohexane. The product was dried in an 80°C oven for 24 hours, and finally the intermediate was obtained.

[0055]

[0056] (2) Synthesis of intermediate polymer: 2.3 g (10.0 mmol) of p-terphenyl was weighed into a 100 mL three-necked flask, 0.48 g (3 mmol) of 3-quinuclidinone hydrochloride and 1.22 g of trifluoromethyl phenyl ketone (7 mmol) were added, and 10 mL of dichloromethane was added to dissolve the reactants. 12 mL of trifluoromethanesulfonic acid and 1 mL of trifluoroacetic acid were added at 0°C, and the reaction was carried out using mechanical stirring for 6 hours. The viscous purple product was poured into a 1 mol / L K2CO3 solution, immersed at room temperature for 24 hours, and filtered to obtain white solid product, which was washed thoroughly with deionized water and dried to obtain the intermediate polymer.

[0057] (3) Synthesis of functionalized polymer: 1 g of the above intermediate polymer was weighed into a 100 mL single neck flask, 15 mL of dimethyl sulfoxide was added, and 150 μL of trifluoroacetic acid was added to promote dissolution of the polymer. After complete dissolution, 0.36 g of potassium carbonate, 0.186 g of intermediate 1 was added, and the reaction was carried out at 60 °C for 16 hours. After that, 300 μL of iodomethane was added, and the reaction was carried out at room temperature for 24 h. The reaction product was poured into ethyl acetate to precipitate a white precipitate, which was washed several times with ethyl acetate and then changed to water washing and dried to obtain a functionalized polymer with anion I".

[0058] (4) Film formation, crosslinking and ion exchange: 1 g of the above modified anion exchange polymer was weighed, 50 mL of dimethyl sulfoxide was added, and after complete dissolution, it was poured into the groove of a flat glass plate, and dried at 80 °C for 48 hours to form a film. After the film was peeled off from the glass plate, it was soaked in a 1 mol / L KOH solution at room temperature for 48 hours to exchange ions to obtain an anion exchange membrane with anion OH - .

[0059] Example 3: aryl is p-terphenyl, x = 50, y = 20

[0060] (1) Synthesis of intermediate 1: A three-necked round-bottom flask equipped with a reflux condenser was charged with 1,6-dibromohexane (10 mL, 65 mmol) and tetrahydrofuran (THF, 300 mL) as solvent. In another three-necked flask, an excess of trimethylamine (TMA) aqueous solution (10 mL, 65 mmol) was heated to 50 °C, and gaseous TMA was introduced into the main reaction system by slow nitrogen blowing. After 12 hours of continuous TMA gas introduction, the system was kept at room temperature for another 12 hours, and white precipitate was generated during the reaction. After the reaction was completed, the white precipitate was separated by filtration. The precipitate was washed with ethyl acetate (EA) three times to remove residual 1,6-dibromohexane. The product was dried in an 80 °C oven for 24 hours to obtain the intermediate.

[0061]

[0062] (2) Synthesis of intermediate polymer: 2.3 g (10.0 mmol) of p-terphenyl was weighed into a 100 mL three-necked flask, 1.13 g (7 mmol) of 3-quinuclidinone hydrochloride and 0.52 g of trifluorophenylacetone (3 mmol) were added, and 10 mL of dichloromethane was added to dissolve the reactants. 12 mL of trifluoromethanesulfonic acid and 1 mL of trifluoroacetic acid were added at 0 °C, and the reaction was carried out for 6 hours with mechanical stirring. The viscous purple product was poured into a 1 mol / L K2CO3 solution, soaked at room temperature for 24 hours, and filtered to obtain a white solid product, which was washed with deionized water and dried to obtain the intermediate polymer.

[0063] (3) Synthesis of functionalized polymer: 1 g of the above intermediate polymer was weighed into a 100 mL single neck flask, 15 mL of dimethyl sulfoxide was added, and 150 μL of trifluoroacetic acid was added to promote dissolution of the polymer. After complete dissolution, 0.36 g of potassium carbonate, 0.186 g of intermediate 1 was added, and the reaction was carried out at 60 °C for 16 hours. After that, 300 μL of iodomethane was added, and the reaction was carried out at room temperature for 24 hours. The reaction product was precipitated into ethyl acetate to obtain a white precipitate. After washing several times with ethyl acetate, the washing was changed to water, and the product was dried to obtain a functionalized polymer with an anion of I.

[0064] (4) Film formation, crosslinking, and ion exchange: 1 g of the above modified anion exchange polymer was weighed, 50 mL of dimethyl sulfoxide was added, and after complete dissolution, it was poured into the groove of a flat glass plate and dried at 80 °C for 48 hours to form a film. After the film was peeled off from the glass plate, it was immersed in a 1 mol / L KOH solution at room temperature for 48 hours to exchange ions to obtain an anion exchange membrane with an anion of OH. -

[0065] Example 4: aryl is biphenyl, x = 75, y = 20

[0066] (1) Synthesis of intermediate 1: A three-necked round-bottom flask equipped with a reflux condenser was charged with 1,6-dibromohexane (10 mL, 65 mmol) and tetrahydrofuran (THF, 300 mL) as a solvent. In another three-necked flask, an excess of trimethylamine (TMA) aqueous solution (10 mL, 65 mmol) was heated to 50 °C, and gaseous TMA was introduced into the main reaction system by slow nitrogen blowing. After 12 hours of continuous TMA gas introduction, the system was kept at room temperature for 12 hours of continuous reaction, during which white precipitate was generated. After the reaction was completed, the white precipitate was separated by filtration. The precipitate was washed with ethyl acetate (EA) three times to remove residual 1,6-dibromohexane. The product was dried in an 80 °C oven for 24 hours to obtain the intermediate.

[0067]

[0068] (2) Synthesis of intermediate polymer: 1.54 g (10.0 mmol) of biphenyl was weighed into a 100 mL three-necked flask, 1.53 g (9.5 mmol) of 3-quinuclidinone hydrochloride and 0.087 g of trifluorophenylacetone (0.5 mmol) were added, and 10 mL of dichloromethane was added to dissolve the reactants. 12 mL of trifluoromethanesulfonic acid and 1 mL of trifluoroacetic acid were added at 0 °C, and the reaction was carried out for 6 hours with mechanical stirring. The viscous purple product was poured into a 1 mol / L K2CO3 solution, soaked at room temperature for 24 hours, and filtered to obtain a white solid product, which was washed with deionized water and dried to obtain the intermediate polymer.

[0069] ​(3) Synthesis of functionalized polymer: 1 g of the above intermediate polymer was weighed into a 100 mL single neck flask, 15 mL of dimethyl sulfoxide was added, and 150 μL of trifluoroacetic acid was added to promote dissolution of the polymer. After complete dissolution, 0.36 g of potassium carbonate, 0.186 g of intermediate 1 was added, and the reaction was carried out at 60 °C for 16 hours. After that, 300 μL of iodomethane was added, and the reaction was carried out at room temperature for 24 h. The reaction product was precipitated into ethyl acetate to obtain a white precipitate. After washing several times with ethyl acetate, the washing was changed to water, and the product was dried to obtain a functionalized polymer with an anion of I.

[0070] (4) Film formation, crosslinking, and ion exchange: 1 g of the above modified anion exchange polymer was weighed, 50 mL of dimethyl sulfoxide was added, and after complete dissolution, it was poured into the groove of a flat glass plate and dried at 80 °C for 48 hours to form a film. After the film was peeled off from the glass plate, it was immersed in a 1 mol / L KOH solution at room temperature for 48 hours to exchange ions to obtain an anion exchange membrane with an anion of OH. -

[0071] Example 5: aryl is m-terphenyl, x = 75, y = 20

[0072] (1) Synthesis of intermediate 1: A three-necked round-bottom flask equipped with a reflux condenser was charged with 1,6-dibromohexane (10 mL, 65 mmol) and tetrahydrofuran (THF, 300 mL) as solvent. In another three-necked flask, an excess of trimethylamine (TMA) aqueous solution (10 mL, 65 mmol) was heated to 50 °C, and gaseous TMA was introduced into the main reaction system by slow nitrogen blowing. After 12 hours of continuous TMA gas introduction, the system was kept at room temperature for another 12 hours, and white precipitate was generated during the reaction. After the reaction was completed, the white precipitate was separated by filtration. The precipitate was washed with ethyl acetate (EA) three times to remove residual 1,6-dibromohexane. The product was dried in an 80 °C oven for 24 hours to obtain the intermediate.

[0073]

[0074] (2) Synthesis of intermediate polymer: 2.3 g (10.0 mmol) of m-terphenyl was weighed into a 100 mL three-necked flask, 1.53 g (9.5 mmol) of 3-quinuclidinone hydrochloride and 0.087 g of trifluorophenylacetone (0.5 mmol) were added, and 10 mL of dichloromethane was added to dissolve the reactants. 12 mL of trifluoromethanesulfonic acid and 1 mL of trifluoroacetic acid were added at 0 °C, and the reaction was carried out for 6 hours with mechanical stirring. The viscous purple product was poured into a 1 mol / L K2CO3 solution, soaked at room temperature for 24 hours, and filtered to obtain a white solid product, which was washed with deionized water and dried to obtain the intermediate polymer.

[0075] ​(3) Synthesis of functionalized polymer: 1 g of the intermediate polymer described above was weighed into a 100 mL single neck flask, 15 mL of dimethylsulfoxide was added, and 150 μL of trifluoroacetic acid was added to facilitate dissolution of the polymer. After complete dissolution, 0.36 g of potassium carbonate, 0.186 g of intermediate 1 was added, and the reaction was allowed to proceed at 60 °C for 16 hours. After this time, 300 μL of iodomethane was added, and the reaction was allowed to proceed at room temperature for 24 hours. The reaction product was poured into ethyl acetate to precipitate a white solid, which was washed several times with ethyl acetate and then with water and dried to obtain the functionalized polymer with anion I".

[0076] (4) Membrane formation, crosslinking, and ion exchange: 1 g of the modified anion exchange polymer described above was weighed into a 50 mL single neck flask, 50 mL of dimethylsulfoxide was added, and the mixture was allowed to dissolve completely. The solution was poured into a groove on a flat glass plate, and the solvent was evaporated at 80 °C for 48 hours to form a membrane. The membrane was peeled off the glass plate and immersed in a 1 mol / L KOH solution at room temperature for 48 hours to exchange the anion to OH - .

[0077] Example 6

[0078] The difference from Example 1 is that in (1) synthesis of intermediate 1: a three necked round bottom flask equipped with a reflux condenser was charged with 1,6-dibromo octane (10 mL, 65 mmol) and tetrahydrofuran (THF, 300 mL) as solvent. In another three necked flask, an excess of aqueous trimethylamine (TMA) solution (10 mL, 65 mmol) was heated to 50 °C, and gaseous TMA was introduced into the main reaction system by slow nitrogen gas purge. After 12 hours of continuous TMA gas purge, the system was maintained at room temperature for another 12 hours, and white precipitate was formed during the reaction. After the reaction was completed, the white precipitate was separated by filtration. The precipitate was washed with ethyl acetate (EA) three times to remove residual 1,6-dibromo octane. The product was dried in an oven at 80 °C for 24 hours to obtain intermediate 1. An anion exchange membrane with OH - was obtained.

[0079]

[0080] Example 7

[0081] The difference from Example 1 is that the synthesis of intermediate 1: a three-necked round bottom flask equipped with a reflux condenser was charged with 1,6-dibromohexane (10 mL, 65 mmol) and tetrahydrofuran (THF, 300 mL) as solvent. In another three-necked flask, an excess of aqueous triethylamine (12 mL, 70 mmol) was heated to 50 °C and gaseous TMA was introduced into the main reaction system by slow nitrogen purge. After 12 hours of TMA gas purge, the system was kept at room temperature for another 12 hours and white precipitate was formed during the reaction. After the reaction was completed, the white precipitate was separated by filtration. The precipitate was washed with ethyl acetate (EA) three times to remove residual 1,6-dibromohexane. The product was dried in an oven at 80 °C for 24 hours and the final anion was OH - .

[0082]

[0083] Example 8

[0084] The difference from Example 1 is that the molar ratio of triflic acid to trifluoroacetic acid is 25:1 and the final anion is OH - .

[0085] Example 9

[0086] The difference from Example 1 is that the molar ratio of triflic acid to trifluoroacetic acid is 2:1 and the final anion is OH - .

[0087] Example 10

[0088] The difference from Example 1 is that 12 mL of triflic acid and 1 mL of trifluoroacetic acid were added at -10 °C and the reaction was stirred for 36 hours using a mechanical stirrer and the final anion is OH - .

[0089] Comparative Example 1

[0090] The difference from Example 1 is that the intermediate polymer was directly used as an anion exchange membrane.

[0091] Test Method:

[0092] Ion conductivity: The OH - ion conductivity of the fully wetted anion exchange membrane in pure water was measured using a four-electrode alternating current impedance method. The specific test conditions are as follows: the sample was assembled in a special test fixture and immersed in pure water at 80 °C, and an electrochemical workstation was used to test the sample alternating current impedance spectrum, and the impedance frequency range was 1 Hz to 4*10 4Hz, perturbation voltage 10 mV, the impedance value of the sample was read from the intersection of the high frequency part of the spectrum line and the real axis, and the ion conductivity was calculated.

[0093] Alkali resistance: test the ion conductivity retention rate of the anion exchange membrane after soaking in 80℃ KOH solution (1 mol / L) for 2000 hours.

[0094] Mechanical strength: test the tensile strength according to the method specified in Chapter 8 of GB / T 20242.3-2022.

[0095] The above test results are listed in Table 1.

[0096] Table 1

[0097]

[0098]

[0099] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects:

[0100] The modified anion exchange polymer of the present application takes an aryl group (such as p-terphenyl) with alkali resistance as part of the main chain, and on this basis, on the one hand, by introducing a cationic group with strong alkali resistance into the main chain of the modified anion exchange polymer, not only the cationic density of the modified anion exchange polymer is increased, but also its stability in a strong alkaline environment is significantly improved. On the other hand, by introducing a side chain containing a cationic group, not only the ion conductivity of the anion exchange membrane is improved, but also its alkali resistance is enhanced. Specifically, the positive charge nitrogen atom (N + ) and the hydroxyl group (OH-) on the side chain form an ion transport channel, and the presence of the R group enables these side chains to be closely combined with the main chain, forming a continuous ion transport network, thereby improving the ion conduction performance of the anion exchange membrane. In addition, by controlling the value range of x and y, the synergistic effect of the aryl main chain structure and the cationic group can be promoted, so that the modified anion exchange polymer can maintain structural integrity under high alkalinity conditions, reduce its degradation probability, and thus improve the ion conductivity of the modified anion exchange polymer, achieving a good balance, and ultimately obtaining an anion exchange membrane with high alkali resistance and high ion conductivity.

[0101] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A modified anion exchange polymer, characterized in that, The modified anion exchange polymer has the following general structural formula: Wherein, R is selected from C1 to C2. 20 Any one of the straight-chain alkylene groups; R1, R2, and R3 are each independently selected from H, C1 to C1. 20 Any one of the straight-chain alkyl groups; x and y represent the molar content of their corresponding repeating units in the modified anion exchange polymer, respectively. The value of x ranges from 0 to 100, and the value of y ranges from 1 to 50, and (x+y)≤100. Ar1, Ar2, and Ar3 are each independently selected from C 12 ~C 40 Any of the aryl groups.

2. The modified anion exchange polymer according to claim 1, characterized in that, The value of y ranges from 5 to 50, and the value of (x+y) ranges from 30 to 95; and / or Ar1, Ar2, and Ar3 are each independently selected from C. 12 ~C 24 Any of the aryl groups; And / or the R mentioned is selected from C1 to C2. 10 Any one of the straight-chain alkylene groups.

3. The modified anion exchange polymer according to claim 2, characterized in that, The value of (x+y) ranges from 70 to 95; and / or Ar1, Ar2, and Ar3 are each independently selected from any one of the following substituents: in This indicates the connection positions of Ar1, Ar2, and Ar3 in the modified anion exchange polymer; And / or the R is selected from any one or more straight-chain alkylene groups from C1 to C8; And / or R1, R2, and R3 are each independently selected from H, C1 to C 10 Any one of the straight-chain alkyl groups.

4. The modified anion exchange polymer according to claim 3, characterized in that, The R is selected from any one of methylene, ethylene, propylene, butylene, pentylene, and hexylene; And / or R1, R2 and R3 are each independently selected from any one of methyl, ethyl, propyl, butyl, pentyl and hexyl.

5. A method for preparing the modified anion exchange polymer according to any one of claims 1 to 4, characterized in that, The preparation method includes: Step S1 involves polymerizing a first reactant comprising aryl compounds, quinine cyclic ketones, trifluoroacetophenone, and an organic acid to obtain a first intermediate polymer. Step S2, comprising the first intermediate polymer, The second reactant, which is an alkaline substance, undergoes a first substitution reaction to obtain the system after the first substitution reaction. Step S3: The system comprising the first substitution reaction and the third reaction material, iodomethane, undergoes a second substitution reaction to obtain the modified anion exchange polymer. Where X is either a Cl element or a Br element; The quinine cyclic ketone compounds are 3-quinine cyclic ketone hydrochloride and / or 3-quinine cyclic ketone; The organic acid is a mixture of trifluoromethanesulfonic acid and trifluoroacetic acid.

6. The method for preparing the modified anion exchange polymer according to claim 5, characterized in that, In step S1, the molar ratio of trifluoromethanesulfonic acid to trifluoroacetic acid is 3 to 25:

1. And / or the temperature of the polymerization reaction is -10 to 10°C; And / or the polymerization reaction time is 3 to 48 hours; And / or the first reaction raw material further includes a first solvent, and / or the first solvent is selected from any one or more of dichloromethane, trichloromethane, chloroform, and tetrahydrofuran.

7. The method for preparing the modified anion exchange polymer according to claim 5 or 6, characterized in that, In step S2, the alkaline substance is selected from any one or more of potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate; and / or the second reaction raw material further includes trifluoromethanesulfonic acid and / or trifluoroacetic acid; And / or the temperature of the first substitution reaction is 60–100 °C; And / or the time for the first substitution reaction is 1 h to 18 h; And / or the second reaction raw material further includes a second solvent, the second solvent being selected from any one or more of dimethyl sulfoxide and N-methylpyrrolidone.

8. The method for preparing the modified anion exchange polymer according to claim 5 or 6, characterized in that, In step S3, the temperature of the second substitution reaction is 25–50°C. The time for the second substitution reaction is 18h to 48h.

9. An anion exchange membrane, obtained by forming a modified anion exchange polymer, characterized in that, The modified anion exchange polymer is the modified anion exchange polymer according to any one of claims 1 to 4.

10. The anion exchange membrane according to claim 9, characterized in that, The anion exchange membrane has a tensile strength of 15–70 MPa, and / or the anion exchange membrane has an ionic conductivity of 90–230 mS / cm at 80°C; and / or the anion exchange membrane retains an ionic conductivity of 93%–99% after being immersed in a KOH solution at 80°C for 2000 hours, wherein the concentration of the KOH solution is 1 mol / L.

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