Cross-linked anion exchange membrane based on styrene copolymerized vinylbenzyl chloride

Abstract

The cross-linked anion exchange membrane based on styrene copolymerized vinylbenzyl chloride has high ionic conductivity and high mechanical strength. According to the technical scheme, the crosslinking process and the membrane forming process are synchronously carried out, the difficulty of casting and membrane laying is not increased while a crosslinking structure is constructed, and the anion exchange membrane has the characteristics of high ionic conductivity and high mechanical strength and is suitable for large-area casting membrane preparation. In addition, the preparation method in the technical scheme is simple in process and relatively low in cost, and has relatively good industrialization potential. The invention relates to a cross-linked anion exchange membrane based on styrene copolymerized vinylbenzyl chloride. The chain structure of the cross-linked anion exchange membrane is as shown in the following formula: # imgabs0 #, wherein A is a unit containing a quaternary amine structure or an imidazolium structure; and B is a unit of a biquaternary amine group with a double-bond alkyl chain, or a unit of an imidazole group with a double-bond alkyl chain.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer functional materials, and more specifically, to a crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene. Background Art

[0002] An anion exchange membrane is a functional thin film with ion exchange function, usually composed of a polymer backbone, cationic charged groups, and freely moving anions. Among them, the content of cationic charged groups directly affects the ion transport ability of the anion exchange membrane. Generally, a high content of charged groups can bring better ionic conductivity. However, an increase in the content of charged groups in the ion exchange membrane will inevitably lead to a decrease in the content of the polymer backbone, and the polymer backbone plays a role in providing mechanical properties and dimensional stability in the anion exchange membrane. To overcome the deterioration of mechanical properties and dimensional stability caused by a high content of cationic groups, the design of crosslinked structures has been widely applied in anion exchange membranes. However, while the crosslinked structure brings improvements in mechanical properties and dimensional stability, it also brings a series of problems, including the gelation problem of highly crosslinked polyelectrolyte casting solutions, the reduction of the ionic conductivity of the membrane, and the deterioration of the processing performance of the membrane. Among them, the gelation problem of highly crosslinked polyelectrolyte casting solutions is particularly prominent. When the crosslinking degree increases, the viscosity of the polyelectrolyte casting solution will increase significantly, eventually leading to the occurrence of gelation. This makes the fluidity of the casting solution poor, and it is difficult to form a film by conventional coating or casting methods, which brings great difficulties to the preparation of anion exchange membranes. Therefore, preparing a highly crosslinked polyelectrolyte casting solution and being able to perform conventional coating and casting are problems to be solved in the large-scale production of anion exchange membranes.

[0003] In the literature (Journal of Power Sources, 594, 2024, 233974; DOI: 10.1016 / j.jpowsour.2023.233974), the authors synthesized poly(styrylbenzoyl chloride-co-styryltetramethylimidazole) (PVBTMIM) polymers and added PEG (polyethylene oxide) with different molecular weights to the membrane to improve the flexibility and conductivity of the membrane. This material has the characteristics of both high ionic conductivity (up to 58.2 mS / cm) and good flexibility (up to 135%). The above prior art improved the performance of the membrane through the physical crosslinked structure formed by the addition of PEG, avoiding the gelation problem of the casting solution caused by chemical crosslinking. However, the addition of PEG also brought problems such as a decrease in the breaking strength of the membrane and mass loss.

[0004] In summary, there is still a challenge in developing an anion exchange membrane with high ion exchange capacity, high ionic conductivity, high crosslinking degree, and easy casting and film laying. Summary of the Invention

[0005] In order to overcome the above problems existing in the prior art, the present invention provides a crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene. The crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene of the present invention has both high ionic conductivity and high mechanical strength. The technical solution of the present invention synchronizes the crosslinking and film-forming processes. While constructing a crosslinked structure, it does not increase the difficulty of casting and laying the film, enabling the anion exchange membrane to have the characteristics of both high ionic conductivity and high mechanical strength, and being suitable for large-area casting and film preparation. In addition, the preparation method in the technical solution of the present invention has a simple process, low cost, and good potential for industrialization and industrial production.

[0006] The technical solution of the present application is as follows: A crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene, characterized in that the chain structure is as shown in the following formula: ; Wherein: a is any integer ≥ 0; b is any integer ≥ 0; c is any integer ≥ 1; A is a unit containing a quaternary amine structure or an imidazolium structure; B is a unit of a bisquaternary amine group with a double-bonded alkyl chain or an imidazole group with a double-bonded alkyl chain.

[0007] Further, in the crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene described above, the unit containing a quaternary amine structure is selected from the following structural groups: , , ; Wherein, R is selected from hydrogen, an alkyl group of C1-C10, and * represents the connection site to the polymer main chain.

[0008] Further, in the crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene described above, the unit containing an imidazolium structure is selected from the following structural groups: , ; Wherein, R is selected from hydrogen, an alkyl group of C1-C10, and * represents the connection site to the polymer main chain.

[0009] Further, in the crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene described above, the unit of the bisquaternary amine group with an alkyl chain is the following structural group: ; Wherein, R' is selected from an alkyl group of C1-C10, and * represents the connection site to the polymer main chain.

[0010] Further, in the aforementioned crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene, the imidazolium unit with a double bond alkyl chain is selected from the following structural groups: , ; wherein, R’ is selected from C1-C10 alkyl, and * represents the connection site with the polymer main chain.

[0011] Further, the preparation method of the aforementioned crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene includes the following steps: (1) In the presence of a first solvent and a protective gas, styrene and vinylbenzyl chloride are polymerized under the action of a catalyst to obtain a styrene-chloromethylstyrene copolymer; (2) A compound containing a bis-secondary amine structure or an imidazole structure is dissolved in a second solvent to prepare a solution of Compound A; a compound containing a chloro group and a double bond structure is dissolved in a second solvent to prepare a solution of Compound B; the solution of Compound A and the solution of Compound B are mixed and reacted to obtain a crosslinking compound; the crosslinking compound is a compound containing a single secondary amine structure and a double bond structure, or a compound containing a monosubstituted imidazole structure and a double bond structure; (3) The styrene-chloromethylstyrene copolymer obtained in step (1), the crosslinking compound obtained in step (2), and a compound containing a quaternary amine structure or an imidazolium structure are dissolved in a third solvent and reacted to obtain a casting solution; then, the casting solution is spread and crosslinked in an oven to obtain a halogen-based crosslinked ion exchange membrane based on styrene copolymerized with chloromethylstyrene; finally, the halogen-based ion exchange membrane is subjected to ion exchange with an alkali solution to obtain a crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene with hydroxide as the anion.

[0012] Further, in the preparation method of the aforementioned crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene, in step (1), the first solvent is selected from one or more of acetonitrile, tetrahydrofuran, 1,2-dichloroethane, and dimethyl sulfoxide; the catalyst is selected from one of azobisisobutyronitrile, azobicyclohexanenitrile, benzoyl peroxide, and di-tert-butyl peroxide.

[0013] Further, in the preparation method of the aforementioned crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene, in step (1), the molar ratio of vinylbenzyl chloride monomer to styrene monomer is 1:(0-4); the molar ratio of the catalyst to the total amount of monomers is 1:(50-5000); the temperature of the polymerization reaction is 50°C - 100°C, and the time is 5h - 50h.

[0014] In the preparation method of the crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene, in step (2), the second solvent is one or more of dimethyl sulfoxide, N,N-dimethylformamide, ethyl acetate, and acetonitrile.

[0015] In the preparation method of the crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene, in step (3), the third solvent is a mixed solvent of water and one solvent of dimethyl sulfoxide, N,N-dimethylformamide, and acetonitrile in a ratio of 1:(100 - 5000), and the film casting temperature is 60 - 120 °C.

[0016] Compared with the prior art, the above technical solutions of the present invention have achieved the following beneficial technical effects: (1) The specific chain structure enables the anion exchange membrane to have high ionic conductivity and high mechanical strength; (2) The specific preparation method enables the crosslinking and film forming processes to proceed simultaneously. While constructing the crosslinked structure, it does not increase the difficulty of casting and film forming, making the anion exchange membrane have the characteristics of both high ionic conductivity and high mechanical strength, and is suitable for large-area casting and film making; (3) The preparation method in the technical solution of the present invention has a simple process, low cost, and good potential for industrialization. Description of the Drawings

[0017] Figure 1 is the 1H NMR spectrum of the crosslinking agent 6-(dimethylamino)-N,N-dimethyl-N-(4-vinylbenzyl)hexan-1-ammonium synthesized in Example 1 (the solvent is deuterated DMSO); Figure 2 is the 1H NMR spectrum of the crosslinking agent 1-(5-hexen-1-yl)-2-methyl-1H-imidazole synthesized in Example 3 (the solvent is deuterated DMSO). Detailed Embodiments

[0018] The following further illustrates the present application with reference to the examples, but it shall not be used as a basis for limiting the present application.

[0019] All the drugs used in the following examples are purchased from Nanjing Jiushan Chemical Co., Ltd.

[0020] Example 1:

[0021] In Example 1, the specific preparation method steps of the anion exchange membrane are as follows: (1) Under nitrogen protection, 6.25 g of styrene and 6.10 g of vinylbenzyl chloride were dissolved in 15 ml of tetrahydrofuran, heated to 65 °C, 5 mg of azobisisobutyronitrile was added, and the reaction was refluxed for 24 hours until the solution became viscous. The product was precipitated in methanol and filtered to obtain the crude product, and then the crude product was redissolved in dichloromethane and precipitated in methanol 3 times, and then dried in a vacuum drying oven at 40 °C to obtain styrene-chloromethylstyrene copolymer.

[0022] (2) Under an ice-water bath environment, 0.86 g of N,N,N',N'-tetramethyl-1,6-hexanediamine (TMHDA) was dissolved in DMF and slowly added to a DMF solution containing 0.84 g of vinylbenzyl chloride, and the reaction was carried out for 30 h to obtain the crosslinking agent 6-(dimethylamino)-N,N-dimethyl-N-(4-vinylbenzyl)hexan-1-ammonium.

[0023] (3) Under an ice-water bath environment, 12.35 g of styrene-chloromethylstyrene copolymer, 1.62 g of 6-(dimethylamino)-N,N-dimethyl-N-(4-vinylbenzyl)hexan-1-ammonium and 1.48 g of trimethylamine were dissolved in a mixed solvent of 15 ml of DMF, 5 ml of DMSO and 0.5 ml of water, and the reaction was carried out for 24 h to obtain the corresponding casting solution; the casting solution was evenly coated on a polytetrafluoroethylene plate and placed in an oven at 80 °C under normal pressure for crosslinking reaction and drying (24 h) to obtain a halogen-type ion exchange membrane; finally, the obtained halogen-type ion exchange membrane was immersed in 1M NaOH solution for ion exchange for 24 h, and then washed 3 times with deionized water to obtain an anion-exchange membrane P(s-vbc)-aH-30-5 with hydroxide as the anion, where P(s-vbc) represents polystyrene chloromethylstyrene copolymer, aH represents the hexylamine group in the crosslinked part, the first number 30 represents the percentage of the number of quaternized structural units in the total structural units, and the second number 5 represents the percentage of the number of crosslinked structural units in the total structural units.

[0024] To prove the successful synthesis of the crosslinking agent 6-(dimethylamino)-N,N-dimethyl-N-(4-vinylbenzyl)hexan-1-ammonium, the prepared sample was detected by nuclear magnetic resonance hydrogen spectrum, as Figure 1 shown. Figure 1 where δ is the chemical shift of hydrogen atoms.

[0025] The ion exchange capacity (IEC) of the P(s-vbc)-aH-30-5 membrane was tested by acid-base titration, and the IEC was obtained as 2.26 mmol / g; the in-plane hydroxide conductivity of the obtained P(s-vbc)-aH-30-5 membrane was tested using the cross-linking impedance method, and the hydroxide conductivity at 15 °C was obtained as 15.4 mS / cm; the water absorption and swelling ratio of the membrane were tested by a membrane thickness gauge and a ten-thousandth balance, and the water absorption at room temperature was obtained as 20.3% and the swelling ratio as 10.2%; the mechanical properties of the P(s-vbc)-aH-30-5 membrane with a water content of 100% were tested by a universal mechanical analyzer, and the breaking strength was obtained as 6.9 Mpa and the elongation at break as 20.2%.

[0026] The reaction route of Example 1 is as follows: 。

[0027] Example 2:

[0028] The difference between this example and Example 1 is only that: in step (3), 1.48 g of trimethylamine was increased to 2.072 g to obtain the P(s-vbc)-aH-40-0 membrane.

[0029] The ion exchange capacity (IEC) of the P(s-vbc)-aH-40-0 membrane was tested by acid-base titration, and the IEC was obtained as 2.94 mmol / g; the in-plane hydroxide conductivity of the membrane was tested using the cross-linking impedance method, and the hydroxide conductivity of the P(s-vbc)-aH-40-0 membrane at 15 °C was obtained as 26.7 mS / cm and at 80 °C as 61.7 mS / cm; the water absorption and swelling ratio of the P(s-vbc)-aH-40-0 membrane were tested by a membrane thickness gauge and a ten-thousandth balance, and the water absorption of the P(s-vbc)-aH-40-0 membrane at room temperature was obtained as 14.4% and the swelling ratio as 8.4%; the mechanical properties of the membrane with a water content of 100% were tested by a universal mechanical analyzer, and the breaking strength of the P(s-vbc)-aH-40-0 membrane was obtained as 8.4 Mpa and the elongation at break as 10.2%.

[0030] To prove the diversity of such cross-linked side chain structures, in Examples 3 and 4, imidazole groups and halogen alkenyls were used to prepare similar cross-linked side chain structures.

[0031] Example 3:

[0032] In Example 3, the specific preparation method steps of the anion exchange membrane are as follows: (1) Under nitrogen protection, 7.29 g of styrene and 4.58 g of vinylbenzyl chloride were dissolved in 15 ml of tetrahydrofuran, heated to 65 °C, 5 mg of azobisisobutyronitrile was added, and the reaction was carried out under reflux condensation for 24 hours until the solution became viscous. The product was precipitated in methanol and filtered to obtain the crude product, and then the crude product was redissolved in dichloromethane and precipitated in methanol 3 times, and then dried in a vacuum drying oven at 40 °C to obtain styrene-chloromethylstyrene copolymer.

[0033] (2) At room temperature, 0.59 g of 6-chloro-1-hexene was dissolved in 5 ml of DMF, and slowly added to a DMF solution containing 0.45 g of 2-methylimidazole and 0.2 g of NaOH, and the reaction was carried out for 30 h. Then 30 ml of ethyl acetate and 20 ml of water were added for extraction 3 times. The organic phase was removed and dried to obtain 1-(5-hexen-1-yl)-2-methyl-1H-imidazole.

[0034] (3) At room temperature, 12.35 g of styrene-chloromethylstyrene copolymer, 1 g of 1-(5-hexen-1-yl)-2-methyl-1H-imidazole and 2.75 g of 1-ethyl-2-methyl-1H-imidazole were dissolved in a mixed solution of 15 ml of DMF, 5 ml of DMSO and 1 ml of water, and reacted for 24 h to obtain the corresponding casting solution; the above-mentioned casting solution was evenly coated on a polytetrafluoroethylene plate and placed in an oven at 80 °C under normal pressure for cross-linking reaction and drying (24 h) to obtain a halogen-type ion exchange membrane; finally, the obtained halogen-type ion exchange membrane was immersed in 1 M NaOH solution for ion exchange for 24 h, and then washed 3 times with deionized water to obtain a P(s-vbc)-imH-30-5 anion exchange membrane with hydroxide as the anion, where P(s-vbc) represents polystyrene chloromethylstyrene copolymer, imH represents the hexylimidazole group in the cross-linked structure, the first number 30 represents the percentage of the number of imidazolium structural units in the total structural units, and the second number 5 represents the percentage of the number of cross-linked structural units in the total structural units.

[0035] The reaction route of Example 3 is as follows: 。

[0036] To prove the successful synthesis of the cross-linking agent 1-(5-hexen-1-yl)-2-methyl-1H-imidazole, the prepared sample was detected by 1H NMR, as Figure 2 shown.

[0037] The ion exchange capacity (IEC) of the P(s-vbc)-imH-30-5 membrane was tested by acid-base titration, and the IEC of the membrane was found to be 2.21 mmol / g. The in-plane hydroxide conductivity of the obtained P(s-vbc)-imH-30-5 membrane was tested using the cross-linking impedance method, and the hydroxide conductivity of the membrane at 15 °C was found to be 9.8 mS / cm. The water absorption and swelling ratio of the membrane were tested using a membrane thickness gauge and a ten-thousandth balance, and the water absorption of the membrane at room temperature was found to be 19.2% and the swelling ratio was 6.8%. The mechanical properties of the P(s-vbc)-imH-30-5 membrane with a water content of 100% were tested using a universal mechanical analyzer, and the breaking strength of the membrane was found to be 5.6 Mpa and the elongation at break was 8.5%.

[0038] Example 4:

[0039] The difference between this example and Example 3 is only that the 1-(5-hexen-1-yl)-2-methyl-1H-imidazole synthesized in step (2) was replaced with purchased 1-vinylimidazole and used in the synthesis of step (3) to prepare the P(s-vbc)-imE-30-5 membrane.

[0040] Furthermore, the ion exchange capacity (IEC) of the P(s-vbc)-imE-30-5 membrane was tested by acid-base titration, and the IEC was found to be 2.23 mmol / g. The in-plane hydroxide conductivity of the obtained P(s-vbc)-imE-30-5 membrane was tested using the cross-linking impedance method, and the hydroxide conductivity at 15 °C was found to be 12.9 mS / cm. The water absorption and swelling ratio of the P(s-vbc)-imE-30-5 membrane were tested using a membrane thickness gauge and a ten-thousandth balance, and the water absorption at room temperature was found to be 14.2% and the swelling ratio was 5.4%. The mechanical properties of the membrane with a water content of 100% were tested using a universal mechanical analyzer, and the breaking strength was found to be 8.8 Mpa and the elongation at break was 7.4%.

[0041] Comparative Example 1:

[0042] The difference between Comparative Example 1 and Example 1 is only that the vinyl benzyl chloride in step (2) was replaced with an equimolar amount of benzyl chloride to prepare the P(s-vbc)-aH-30-0 membrane.

[0043] The ion exchange capacity (IEC) of the P(s-vbc)-aH-30-0 membrane was tested by acid-base titration, and the IEC was obtained as 2.18 mmol / g; the in-plane hydroxide conductivity of the obtained P(s-vbc)-aH-30-0 membrane was tested by the cross-linking impedance method, and the hydroxide conductivity at 15 °C was obtained as 16.3 mS / cm; the water absorption and swelling ratio of the P(s-vbc)-aH-30-0 membrane were tested by a film thickness gauge and a ten-thousandth balance, and the water absorption of the membrane at room temperature was obtained as 51.2% and the swelling ratio as 28.5%; the mechanical properties of the P(s-vbc)-aH-30-0 membrane with a water content of 100% were tested by a universal mechanical analyzer, and the breaking strength was obtained as 1.6 Mpa and the elongation at break as 38.2%.

[0044] Comparative Example 2:

[0045] In the literature (Journal of Power Sources, 594, 2024, 233974; DOI: 10.1016 / j.jpowsour.2023.233974), the authors synthesized poly(styryl chloride-co-styryl tetramethylimidazole) (PVBTMIM) by a one-step method, and mixed polyethylene oxide (PEG) with different molecular weights with PVBTMIM in a mass ratio of 1:9, and then prepared PEGx-PVBTMIM membranes (x represents the number-average molecular weight of PEG, which are 200, 600, and 2000 respectively) by the solution casting method. The ion exchange capacity of this anion exchange membrane was 1.1 - 1.4 mmol / g; the water absorption at room temperature was 67% - 82.4%, and the swelling ratio was 11.9% - 14.0%; the breaking strength at room temperature in the 100% water-containing state was 2 - 7.5 MPa, and the elongation at break was 60 - 174%; the hydroxide conductivity at 80 °C was 29.1 - 58.2 mS / cm. Taking PEG600-PVBTMIM as an example, its ion exchange capacity was 1.12 mmol / g; the water absorption at room temperature was 75.7%, the swelling ratio was 13.3%; the breaking strength at room temperature in the 100% water-containing state was 2.5 MPa, and the elongation at break was 142%; the hydroxide conductivity at 80 °C was 53.3 mS / cm.

[0046] The following Table 1 summarizes some test data of the examples and comparative examples. It can be seen from the data in the table that the cross-linked anionic exchange membrane based on styrene copolymerized with chloromethylstyrene disclosed in the examples of the present invention has successfully improved the ion transport performance and the breaking strength through the introduction of a cross-linked structure. At the same time, since the present invention realizes the simultaneous occurrence of the cross-linking and film casting processes, it effectively reduces the viscosity of the casting solution and avoids the premature gelation of the film casting solution.

[0047] Table 1: Test Data Test sample Ion exchange capacity (mmol / g) Water absorption rate (%) Swelling ratio (%) Tensile strength (MPa) Elongation at break (%) Hydroxide conductivity @ 15°C (mS / cm) Hydroxide conductivity @ 80°C (mS / cm) Example 1 2.26 20.3 10.2 6.9 20.2 15.4 45.7 Example 2 2.94 27.1 14.4 8.4 10.2 26.7 61.7 Example 3 2.21 19.2 6.8 5.6 8.5 9.8 44.1 Example 4 2.23 14.2 5.4 8.8 7.4 12.9 58.1 Comparative example 1 2.18 51.2 28.5 1.6 38.2 16.3 37.5 Comparative example 2 1.12 75.7 13.3 2.5 142 / 53.3

[0048] Compared with the comparative example, since the present invention adopts a chemical cross-linking method, it has achieved higher breaking strength and lower absorption swelling at a higher ion exchange capacity. At the same time, the increase in ion exchange capacity and the use of a cross-linking agent with ionic groups also endow the anion exchange membrane of the present invention with a relatively high ionic conductivity.

[0049] To prove the generation of the cross-linked structure in the ion exchange membrane, a method of redissolving by immersion in a solvent was used for verification. The anion exchange membrane prepared in Example 1 was red-immersed in DMF and stirred at 50 °C for 4 h. A large amount of insoluble matter was present in the solution. The anion exchange membrane prepared in Comparative Example 1 was red-immersed in DMF and stirred at 50 °C for 4 h. The solution was clear and transparent. This indicates that the present invention successfully constructed a cross-linked structure during the film casting process.

[0050] It should be noted that the structural formulas of the anion exchange membranes obtained in the examples are only two specific forms of the chain structure of the present invention. The present invention is not limited to the above examples. Polymers prepared according to the technical solution of the present invention and having the chain structure described in the present invention all fall within the scope of the present invention.

[0051] The above general description of the invention involved in this application and the description of its specific embodiments should not be construed as limiting the technical solution of the invention. Those skilled in the art can, based on the disclosure of this application, without departing from the constituent elements of the invention involved, add, subtract, or combine the disclosed technical features in the above general description or / and specific embodiments (including examples) to form other technical solutions that fall within the scope of protection of this application.

Claims

1. A crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene, characterized in that, The chain structure is shown in the following formula: ； Wherein: a is an arbitrary integer ≥ 0; b is an arbitrary integer ≥ 0; c is an arbitrary integer ≥ 1; A is a unit containing a quaternary ammonium structure or an imidazolium structure; B is a unit of a bisquaternary ammonium group with a double-bonded alkyl chain or a unit of an imidazole group with a double-bonded alkyl chain.

2. The crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene according to claim 1, wherein The unit containing a quaternary ammonium structure is selected from the following structural groups: 、 、 ； Wherein, R is selected from hydrogen, an alkyl group having 1 to 10 carbon atoms, and * represents the connection site to the polymer main chain.

3. The crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene according to claim 1, characterized in that, The unit containing an imidazolium structure is selected from the following structural groups: 、 ； Wherein, R is selected from hydrogen, an alkyl group having 1 to 10 carbon atoms, and * represents the connection site to the polymer main chain.

4. The crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene according to claim 1, characterized in that, The unit of the bisquaternary ammonium group with an alkyl chain is the following structural group: ； Wherein, R’ is selected from an alkyl group having 1 to 10 carbon atoms, and * represents the connection site to the polymer main chain.

5. The crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene according to claim 1, characterized in that, The imidazole group unit with a double-bonded alkyl chain is selected from the following structural groups: 、 ； Wherein, R’ is selected from an alkyl group having 1 to 10 carbon atoms, and * represents the connection site to the polymer main chain.

6. The crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene according to claim 1, characterized in that, The preparation method of the crosslinked anion exchange membrane comprises the following steps: (1) In the presence of a first solvent and a protective gas, styrene and vinylbenzyl chloride are subjected to a polymerization reaction under the action of a catalyst to obtain a styrene-chloromethylstyrene copolymer; (2) A compound containing a bis-secondary amine structure or an imidazole structure is dissolved in a second solvent to prepare a solution of compound A; a compound containing a chlorine group and a double-bond structure is dissolved in a second solvent to prepare a solution of compound B; the solution of compound A and the solution of compound B are mixed and reacted to obtain a crosslinking compound; the crosslinking compound is a compound containing a single secondary amine structure and a double-bond structure or a compound containing a monosubstituted imidazole structure and a double-bond structure; (3) The styrene-chloromethylstyrene copolymer obtained in step (1), the crosslinking compound obtained in step (2), and a compound containing a quaternary ammonium structure or an imidazolium structure are dissolved in a third solvent and reacted to obtain a casting solution; then, the casting solution is spread and crosslinked in an oven to obtain a halogen-based crosslinked ion exchange membrane of styrene copolymerized chloromethylstyrene; finally, the halogen-based ion exchange membrane is subjected to ion exchange with an alkali solution to obtain a crosslinked anion exchange membrane of styrene copolymerized chloromethylstyrene with hydroxide as the anion.

7. The crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene according to claim 6, wherein, In step (1), the first solvent is selected from one or more of acetonitrile, tetrahydrofuran, 1,2-dichloroethane, and dimethyl sulfoxide; the catalyst is selected from one of azobisisobutyronitrile, azobicyclohexanenitrile, benzoyl peroxide, and di-tert-butyl peroxide.

8. The crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene according to claim 6, characterized in that, In step (1), the molar ratio of vinylbenzyl chloride monomer to styrene monomer is 1:(0 - 4); the molar ratio of the catalyst to the total amount of monomers is 1:(50 - 5000); the temperature of the polymerization reaction is 50°C - 100°C, and the time is 5h - 50h.

9. The crosslinked anion exchange membrane based on styrene copolymerized with chloromethylstyrene according to claim 6, wherein In step (2), the second solvent is one or more of dimethyl sulfoxide, N,N-dimethylformamide, ethyl acetate, and acetonitrile.

10. The crosslinked anionic exchange membrane based on styrene copolymerized with chloromethylstyrene according to claim 6, characterized in that, In step (3), the third solvent is a mixed solvent of water and one of dimethyl sulfoxide, N,N-dimethylformamide, and acetonitrile in a ratio of 1:(100 - 5000), and the film casting temperature is 60 - 120°C.

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