Branched aromatic copolymer, preparation method thereof and anion exchange membrane

Abstract

The invention belongs to the technical field of ion exchange membranes, and particularly relates to a branched aromatic copolymer, a preparation method thereof and an anion exchange membrane. According to the invention, 2, 4, 6-tri (4-(9, 9 '-spiro [fluorene]-2-yl) phenyl)-1, 3, 5-triazine is introduced as a three-dimensional rigid branching center and is accurately polymerized with a biaryl compound and N-methyl-4-piperidone, so that a branching structure with a highly ordered aromatic skeleton is successfully constructed. On the basis of retaining an aromatic main chain structure, through the introduction of a 2, 4, 6-tri (4-(9, 9 '-spiro [fluorene]-2-yl) phenyl)-1, 3, 5-triazine branched structure, the ionic conductivity and hydrophilic-hydrophobic balance characteristic of the membrane are synergistically regulated and controlled, and on the premise of maintaining a relatively low swelling ratio, high ionic conductivity and excellent mechanical properties are realized at the same time.

Description

Technical Field

[0001] This invention belongs to the field of ion exchange membrane technology, specifically relating to a branched aromatic hydrocarbon copolymer, its preparation method, and an anion exchange membrane. Background Technology

[0002] Among numerous hydrogen production technologies, water electrolysis has become a key pathway to achieving a low-carbon energy transition due to its green and environmentally friendly advantages and its ability to be combined with renewable energy sources. Anion exchange membrane water electrolysis, a promising new hydrogen production method that has garnered significant attention in recent years, combines the high stability of traditional alkaline water electrolysis with the high efficiency of proton exchange membrane water electrolysis. This allows for efficient hydrogen production at a lower cost while reducing reliance on precious metal catalysts.

[0003] Hydrogen production through water electrolysis has become a key pathway to achieving a low-carbon energy transition due to its green and environmentally friendly nature and its compatibility with renewable energy sources. Anion exchange membrane water electrolysis technology combines the stability of traditional alkaline electrolysis with the high efficiency of proton exchange membrane electrolysis, while reducing reliance on precious metal catalysts, resulting in significant cost advantages and attracting considerable attention in recent years.

[0004] However, the commercialization of anion exchange membrane technology is severely hampered by the performance of its core component, the anion exchange membrane. An ideal anion exchange membrane needs to simultaneously possess high hydroxide ion conductivity, excellent mechanical strength, good dimensional stability, and long-term alkali resistance. Existing anion exchange membrane materials, in pursuit of high conductivity and increased ion exchange capacity, often lead to excessive membrane swelling and decreased mechanical strength; conversely, enhancing the rigidity of the polymer backbone to improve mechanical properties and dimensional stability may inhibit the formation of ion transport channels, thus reducing conductivity.

[0005] To this end, existing technologies optimize membrane structures through molecular design; for example, reference 1: High-performance spiro-branched polymeric membranes for sustainability applications; Nature Sustainability 2024. 7 References 910-919 report a superacid-catalyzed condensation polymer based on N-methyl-4-piperidinone and 9,9'-spirodifluorene. The core of this approach lies in using stereoscopic spirodifluorene monomers to regulate the topology and orientation of the branched chains. The loosely stacked chain structure lowers the energy barriers for ion dissociation and diffusion within the polymer network, thus facilitating ion transport. However, this type of lightly cross-linked polymer structure still has limitations in regulating hydrophilic-hydrophobic microphase separation and balancing conductivity-mechanical properties; the continuity and uniformity of its ion transport channels need improvement, and it still faces significant swelling problems at higher ion capacities. Summary of the Invention

[0006] To address the shortcomings of existing polymers in regulating hydrophilic-hydrophobic microphase separation and balancing conductivity and mechanical properties, this invention provides a branched aromatic hydrocarbon copolymer, its preparation method, and an anion exchange membrane. This invention introduces 2,4,6-tris(4-(9,9'-spirocyclic [fluorene]-2-yl]phenyl)-1,3,5-triazine (TST) as a three-dimensional rigid branching center. Through precise polymerization with biaryl compounds and N-methyl-4-piperidinone, a branched structure with a highly ordered aromatic hydrocarbon skeleton is successfully constructed. While retaining the aromatic backbone structure, the introduction of the TST branching structure synergistically regulates the membrane's ion conductivity and hydrophilic-hydrophobic balance, achieving high ionic conductivity and excellent mechanical properties while maintaining a low swelling ratio.

[0007] This invention introduces TST as a three-dimensional rigid branching center, using the rigid spirocyclic unit of TST as a three-dimensional framework, and forming a highly symmetrical spatial network through triazine center bridging, breaking through the limitations of the planar configuration of traditional crosslinking agents. This three-dimensional architecture not only significantly improves crosslinking efficiency, enabling the construction of a continuous and interconnected three-dimensional network at lower doping levels, but also creates a superior channel environment for ion transport.

[0008] This invention can precisely control the density of branching points by adjusting the proportion of TST branched structures, thereby regulating the size and connectivity of ion transport channels and the crosslinking density of polymer networks, ultimately achieving synergistic optimization of membrane conductivity, mechanical strength and swelling behavior.

[0009] The first objective of this invention is to provide a branched aromatic hydrocarbon copolymer, the chemical structural formula of which is as follows: ; In the formula, n = 0.01 to 0.5; Ar is a biaryl compound.

[0010] Preferably, Ar is selected from any one of the following groups: .

[0011] It should be noted that 2,4,6-tris(4-(9,9'-spirocyclic [fluorene]-2-yl]phenyl)-1,3,5-triazine forms a uniformly sized and orderly three-dimensional nanochannel network through the synergistic effect of a rigid framework and a conjugated system. It exhibits a long-range ordered phase separation morphology, with channel continuity significantly superior to the disordered pore structures formed by traditional crosslinking agents. This well-ordered topology significantly enhances ionic conductivity while maintaining excellent dimensional stability. Simultaneously, the rigid framework ensures the durability of the channel structure through stable spatial support, the triazine centers reduce ion transport resistance through optimized electron distribution, and the precisely controlled hydrophobic-hydrophilic balance promotes the formation of an ideal microphase separation morphology. This multi-level synergistic effect significantly reduces the ion transport barrier within the channels while maintaining the mechanical integrity of the membrane material.

[0012] A second objective of this invention is to provide a method for preparing branched aromatic copolymers, comprising the following steps: Using 2,4,6-tris(4-(9,9'-spirocyclic [fluorene]-2-yl]phenyl)-1,3,5-triazine as a three-dimensional rigid branching center, a continuous polycondensation reaction was carried out with biaryl compounds and N-methyl-4-piperidinone under acid catalysis to obtain a branched aromatic copolymer.

[0013] Preferably, the specific preparation method of the branched aromatic hydrocarbon copolymer is as follows: 2,4,6-tris(4-(9,9'-spirocyclic[fluorene]-2-yl)phenyl)-1,3,5-triazine, biaryl compounds and piperidinone were dissolved in haloalkanes, and acid was added at 0℃~5℃ to carry out a continuous polycondensation reaction to obtain branched aromatic copolymers.

[0014] Preferably, the molar ratio of the biaryl compound to piperidinone is 1:1 to 2; the molar ratio of the biaryl compound to 2,4,6-tris(4-(9,9'-spirocyclic [fluorene]-2-yl]phenyl)-1,3,5-triazine is 1:0.01 to 1. Adjusting the ratio of 2,4,6-tris(4-(9,9'-spirocyclic [fluorene]-2-yl]phenyl)-1,3,5-triazine can finely control the micropore size and network interconnectivity of the polymer film; significantly improve ionic conductivity; synergistically enhance mechanical strength and chemical stability; and ultimately achieve a balance between conductivity and stability.

[0015] Preferably, the continuous polycondensation reaction time is 10 to 14 hours.

[0016] Preferably, the biaryl compound is biphenyl or p-terphenyl; the piperidinone is N-methyl-4-piperidinone.

[0017] Preferably, the molar ratio of the biaryl compound to the acid is 1:8 to 12.

[0018] Preferably, the acid is trifluoroacetic acid and trifluoromethanesulfonic acid; the molar ratio of trifluoroacetic acid to trifluoromethanesulfonic acid is 1:10.

[0019] Preferably, the halogenated hydrocarbon is dichloromethane or 1,2-dichloroethane.

[0020] The third objective of this invention is to provide an anion exchange membrane, which is obtained by quaternizing a branched aromatic hydrocarbon copolymer, forming a film, and subjecting it to hydroxide ion exchange treatment by immersion in an alkaline solution.

[0021] Preferably, the specific preparation method of the anion exchange membrane is as follows: The branched aromatic copolymer was dissolved in a solvent, iodomethane was added, and the reaction was carried out under light-protected conditions to obtain a quaternized polymer. The quaternized polymer was dissolved in a solvent, cast onto a substrate, dried to form a film, and the resulting film was immersed in an alkaline solution for ion exchange to obtain an anion exchange membrane.

[0022] Preferably, the ratio of branched aromatic copolymer to iodomethane is 1.0g:0.5mL to 1mL.

[0023] Preferably, the ratio of branched aromatic copolymer to solvent is 1.0g: 5mL to 30mL.

[0024] Preferably, the solvent is dimethyl sulfoxide, N-methylpyrrolidone, or N,N-dimethylformamide.

[0025] Preferably, the alkaline solution is a KOH solution or a NaOH solution.

[0026] Compared with the prior art, the present invention has the following technical effects: This invention introduces 2,4,6-tris(4-(9,9'-spirocyclic [fluorene]-2-yl]phenyl)-1,3,5-triazine as a three-dimensional rigid branching center. Through polymerization with biaryl compounds and N-methyl-4-piperidinone, a branched structure with a highly ordered aromatic backbone was successfully constructed. While retaining the aromatic backbone structure, the introduction of the 2,4,6-tris(4-(9,9'-spirocyclic [fluorene]-2-yl]phenyl)-1,3,5-triazine branching structure synergistically regulates the ion conductivity and hydrophilic-hydrophobic balance of the membrane, achieving high ionic conductivity and excellent mechanical properties while maintaining a low swelling ratio.

[0027] The preparation process of this invention is simple and efficient, which not only significantly improves the conductivity of the membrane material, but also effectively inhibits the swelling behavior of the polymer chain, thereby significantly improving the alkaline stability of the membrane.

[0028] The anion exchange membrane prepared by this invention exhibits excellent overall performance, combining high hydroxide conductivity and low swelling ratio at 80℃, significantly outperforming traditional linear polymer membranes. This membrane enhances molecular chain entanglement through the construction of a three-dimensional cross-linked network, demonstrating good mechanical stability. In electrochemical applications, it exhibits low polarization impedance and superior practical potential. Attached Figure Description

[0029] Figure 1 The NMR spectrum of the anion exchange membrane prepared in Example 1.

[0030] Figure 2 OH groups of anion exchange membranes prepared in Examples 1 and 2 at different temperatures - Electrical conductivity.

[0031] Figure 3 Mechanical properties of the anion exchange membranes prepared in Examples 1 and 2.

[0032] Figure 4 The swelling rate of the anion exchange membranes prepared in Examples 1 and 2 at different temperatures.

[0033] Figure 5 Polarization curves of the anion exchange membranes prepared in Examples 1 and 2 in an electrolytic cell. Detailed Implementation

[0034] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention will be further described below with reference to specific embodiments and accompanying drawings. Unless otherwise specified, all reagents used in this invention are commercially available, and all methods used are conventional techniques in the art.

[0035] Example 1 A method for preparing an anion exchange membrane includes the following steps: In a 250 mL three-necked flask, 0.153 mmol of 2,4,6-tris(4-(9,9'-spirocyclo[fluorene]-2-yl)phenyl)-1,3,5-triazine, 15.2 mmol of p-terphenyl, and 15.4 mmol of N-methyl-4-piperidinone were added sequentially, followed by 26 mL of dichloromethane as the reaction solvent. The mixture was stirred continuously for 10 minutes to ensure complete dissolution of the starting materials. The reaction system was transferred to an ice-water bath and cooled to 0 °C. Then, 15.4 mmol of trifluoroacetic acid was slowly added while stirring for 10 minutes. Next, 154.3 mmol of trifluoromethanesulfonic acid was added dropwise. The reaction was continued at a constant temperature of 0 °C for 6 hours, during which the solution gradually turned into a viscous, bluish-black state. After the reaction was terminated, the resulting viscous liquid was poured into a 1 M K₂CO₃ aqueous solution, and a yellowish-brown polymer precipitate immediately formed. After standing for 2 hours, the precipitate was mechanically crushed and stirred continuously in a 1 M K₂CO₃ solution for 24 hours. After repeated washing with deionized water until neutral, the final product was dried in an oven at 80°C for 24 hours to obtain a branched aromatic copolymer, denoted as TPTP-0.01.

[0036] 1.0 g of TPTP-0.01 was dissolved in 20 mL of dimethyl sulfoxide, and then 1 mL of iodomethane was added to the solution to initiate a quaternization reaction. The reaction system was placed in a light-protected, sealed environment and stirred continuously for 24 hours. After the reaction was complete, insoluble matter was removed by vacuum filtration, and the filtrate was slowly added dropwise to ethyl acetate to precipitate the polymer. The resulting precipitate was repeatedly washed with deionized water, filtered to collect the solid product, and dried in an oven at 80 °C for 24 hours to obtain the quaternized polymer, denoted as QTPTP-0.01.

[0037] 0.8 g of QTPTP-0.01 was dissolved in 20 mL of dimethyl sulfoxide. The homogeneous solution was cast onto a clean glass plate and dried at 80 °C to form a film. Finally, the dried QTPTP-0.01 membrane was peeled off from the glass substrate and immersed in a 1 mol / L NaOH solution for ion exchange treatment, converting the anions in the QTPTP-0.01 membrane into hydroxide ions, thus obtaining an anion exchange membrane. The specific synthetic route is as follows:

[0038] .

[0039] Example 2 A method for preparing an anion exchange membrane includes the following steps: The difference from Example 1 is that biphenyl is used instead of terphenyl.

[0040] In a 100 mL three-necked flask, 0.153 mmol of 2,4,6-tris(4-(9,9'-spirocyclo[fluorene]-2-yl)phenyl)-1,3,5-triazine, 15.2 mmol of biphenyl, and 15.4 mmol of N-methyl-4-piperidinone were added sequentially, followed by 10 mL of dichloromethane as a solvent. The mixture was stirred at room temperature for 5 minutes to ensure complete dissolution. The reaction mixture was transferred to an ice-water bath and cooled to 0 °C. Then, 15.4 mmol of trifluoroacetic acid was slowly added, and the mixture was stirred for 10 minutes. Next, 154.3 mmol of trifluoromethanesulfonic acid was slowly added dropwise. The reaction was maintained at 0 °C for 4 hours, during which the solution gradually turned into a viscous, bluish-black state. After the reaction was completed, the mixture was slowly poured into a 1 M K₂CO₃ aqueous solution, and a yellowish-brown polymer precipitate immediately formed. After standing for 2 hours, the precipitate was mechanically crushed and stirred continuously in a 1 M K₂CO₃ solution for 24 hours. After the precipitate was repeatedly washed with deionized water until neutral, it was dried in an oven at 80°C for 24 hours to obtain a branched aromatic copolymer, denoted as TPBP-0.01.

[0041] 1.0 g of TPBP-0.01 was dissolved in 20 mL of dimethyl sulfoxide. Under light-protected and sealed conditions, 1.0 mL of iodomethane was added to the solution, and the mixture was stirred at room temperature for 24 hours to carry out the quaternization reaction. After the reaction was complete, the insoluble matter was removed by vacuum filtration. The filtrate was added dropwise to ethyl acetate to precipitate the polymer. The precipitate was repeatedly washed with deionized water, filtered, and the solid product was collected and dried in an oven at 80 °C for 24 hours to obtain the quaternized polymer, denoted as QTPBP-0.01.

[0042] 0.8 g of QTPBP-0.01 was dissolved in 20 mL of dimethyl sulfoxide. The resulting solution was uniformly cast onto a clean glass plate and dried at 80 °C to form a film. The dried QTPBP-0.01 film was peeled off from the glass substrate and immersed in a 1 mol / L NaOH solution for ion exchange treatment, converting the anions in the QTPBP-0.01 film into hydroxide ions, thus obtaining an anion exchange membrane. The specific synthetic route is as follows:

[0043] .

[0044] Comparative Example 1 A method for preparing an anion exchange membrane includes the following steps: The difference from Example 1 is that 2,4,6-tris(4-(9,9'-spirocyclic[fluorene]-2-yl)phenyl)-1,3,5-triazine was not added.

[0045] Weigh 13.03 mmol of terphenyl into a 100 mL three-necked flask, add 15.63 mmol of N-methylpiperidone, stir for 2 minutes, then add 10 mL of dichloromethane. Place the flask in an ice-salt bath and stir for 10 minutes. Add 15.63 mmol of trifluoroacetic acid dropwise, stir for 10 minutes, then add 156.31 mmol of trifluoromethanesulfonic acid. Maintain a constant temperature of 0°C for 5 hours. When the reaction reaches a blue-black viscous state, pour the reactants into 250 mL of 1 M K₂CO₃ solution. A white, strip-shaped solid precipitates. Crush the solid and soak it in 250 mL of 1 M K₂CO₃ solution for 24 hours. Then wash the solid particles three times with deionized water and dry at 80°C for 24 hours. The resulting polymer is denoted as PTP.

[0046] Weigh 1 g of PTP into a 50 mL single-necked flask, add 20 mL of dimethyl sulfoxide and 0.7 mL of iodomethane, stir at room temperature in the dark for 24 h, and filter under reduced pressure after the reaction is complete. Add the filtrate dropwise to ethyl acetate to precipitate the polymer. Wash repeatedly with deionized water and collect the solid product. Dry in an oven at 80 °C for 24 h to obtain the quaternized polymer, denoted as QPTP.

[0047] 0.8 g of QPTP was dissolved in 20 mL of dimethyl sulfoxide. After complete dissolution, the solution was uniformly cast onto a clean glass plate. The glass plate containing the solution was placed in an 80 °C oven to dry and form a film. After the solvent had completely evaporated, the dried QPTP membrane was peeled off from the glass substrate and then immersed in a 1 mol / L NaOH solution for ion exchange treatment, converting the anions in the QPTP membrane into hydroxide ions to obtain an anion exchange membrane. The specific synthetic route is shown in the figure below:

[0048] .

[0049] 1. Nuclear magnetic resonance (NMR) test.

[0050] The QTPTP-0.01 membrane prepared in Example 1 was subjected to NMR scanning, and the results are as follows: Figure 1 As shown, 7.34 ppm is the peak of 2,4,6-tris(4-(9,9'-spirocyclic [fluorene]-2-yl)phenyl)-1,3,5-triazine CH. 7.5-7.73 ppm are the CH peaks on the aryl group, 3.2 ppm is the characteristic peak of the methyl group on piperidine, and 2.45 ppm is the characteristic peak of deuterated dimethyl sulfoxide.

[0051] 2. Conductivity test.

[0052] Conductivity measurements were performed using a Shanghai Chenhua electrochemical workstation (CHI 760E) via a four-electrode AC impedance method. Before testing, the membrane was cut to 1.0 cm × 4.0 cm pieces and immersed in a 1 M KOH solution in an 80°C oven for 12 hours to convert it to the corresponding anionic form. After removal, it was ultrasonically cleaned to remove residual reagents, then fixed using a self-made conductivity fixture and immersed in water at 100% relative humidity. Tests were conducted within the temperature range of 30°C to 80°C, and the measured results are the transverse conductivity of the membrane surface. The value can be calculated using the following formula:

[0053] ; In the formula, σ is the ionic conductivity; L is the effective distance between electrodes, in cm; and A is the cross-sectional area of ​​the membrane, in cm². 2 R is the measured impedance value.

[0054] Table 1. Ion conductivity and swelling ratio results of the anion exchange membranes prepared in Examples 1, 2, and Comparative Example 1. like Figure 2 As shown in Figure 1 and Table 1, the anion exchange membrane prepared in Example 1 exhibited an ionic conductivity of 135.35 mS / cm measured at 80 °C, demonstrating excellent ion transport performance. The membrane prepared in Example 2 achieved an even higher ionic conductivity of 169.2 mS / cm under the same testing conditions. This indicates that the adjustments made in material design, microstructure, or preparation process in Example 2 effectively optimized the ion channel construction and ion migration efficiency of the membrane, providing clear experimental evidence for further improving the electrochemical performance of the membrane.

[0055] 3. Swelling rate test.

[0056] The dry membrane material was cut into rectangular samples of 4.00 cm × 3.00 cm and immersed in 1 M KOH solution for 24 hours to complete the ion exchange process from iodide ions to hydroxide ions, thereby obtaining a hydroxide-type anion exchange membrane. Subsequently, the membrane surface was thoroughly cleaned with deionized water to remove residual alkali, and then immersed in deionized water for later use.

[0057] To investigate the effect of temperature on membrane swelling behavior, wet hydroxide-type anion exchange membrane samples were sequentially placed in water baths at 40℃, 50℃, 60℃, 70℃, and 80℃. Each temperature was maintained for 30 minutes to ensure the membrane reached swelling equilibrium. Afterward, the samples were removed, and the surface moisture was quickly and gently blotted dry with filter paper. The length and width of the swollen membrane were measured, and the corresponding temperatures were recorded. The swelling rate was calculated using the following formula:

[0058] SD=( + ) / 2×100; In the formula, SD is the swelling ratio, x is the length after swelling in cm, and y is the width after swelling in cm.

[0059] like Figure 3 As shown in Table 1, the anion exchange membranes prepared in Examples 1 and 2 both exhibited excellent dimensional stability at 80°C, with swelling rates below 30%. This result indicates that the membrane materials of both examples can effectively maintain structural integrity under high temperature and high humidity conditions, without excessive expansion or deformation, providing an important guarantee for the long-term stability and durability of the materials in practical applications.

[0060] 4. Mechanical performance testing.

[0061] Tensile properties were tested using a tensile testing machine. Before testing, the membrane sample was cut into strips of 1cm × 5cm, and the actual width at the narrowest point and the average thickness of the sample were measured. During testing, the sample was clamped at both ends in a fixture and stretched at a constant rate until the sample broke, while simultaneously recording the stress-strain curve. Based on the maximum load and tensile displacement at fracture, the tensile strength and elongation at break of the membrane could be calculated.

[0062] like Figure 4 As shown, the anion exchange membrane of Example 1 has higher mechanical strength, with a tensile strength of 33.01 MPa, indicating that it has good structural stability and resistance to deformation. The tensile strength of the anion exchange membrane of Example 2 is 28.41 MPa, which is slightly lower than that of Example 1, but still within a reasonable high strength range, and can meet the basic mechanical requirements of anion exchange membranes in practical applications.

[0063] 5. Electrolysis of water test.

[0064] A simple electrolytic cell was assembled at 80℃ using 1M KOH as the electrolyte. The electrolytic cell used an anion exchange membrane as the diaphragm, and non-ionomerized Ni-based metal alloy electrodes on both sides: the anode was Ni-Fe alloy foam, and the cathode was Ni-Mo alloy foam. Its performance was tested using linear sweep voltammetry at a scan rate of 100 mV / s.

[0065] At 80°C, the anion exchange membrane prepared in Example 1 was subjected to a 1A cm⁻¹ test. -2 When tested at high current density, its battery voltage was 1.78V. The anion exchange membrane prepared in Example 2 performed better under the same conditions, with the battery voltage further reduced to 1.75V, indicating that it has more efficient ion conduction capability and lower internal impedance, thereby improving the overall voltage efficiency of the system while maintaining efficient energy conversion.

[0066] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended scope of protection is intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of this invention.

[0067] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of protection of this invention and its equivalents, this invention also intends to include these modifications and variations.

Claims

1. A branched aromatic copolymer, characterized in that, The chemical structural formula of the branched aromatic copolymer is as follows: ； In the formula, n = 0.01 to 0.5; Ar is a biaryl compound.

2. The branched aromatic copolymer according to claim 1, characterized in that, Ar is selected from any of the following groups: 。 3. A method for preparing the branched aromatic copolymer according to claim 1 or 2, characterized in that, Includes the following steps: Using 2,4,6-tris(4-(9,9'-spirocyclic [fluorene]-2-yl]phenyl)-1,3,5-triazine as a three-dimensional rigid branching center, a continuous polycondensation reaction was carried out with biaryl compounds and N-methyl-4-piperidinone under acid catalysis to obtain a branched aromatic copolymer.

4. The method for preparing branched aromatic copolymers according to claim 3, characterized in that, Includes the following steps: 2,4,6-tris(4-(9,9'-spirocyclic[fluorene]-2-yl)phenyl)-1,3,5-triazine, biaryl compounds and piperidinone were dissolved in haloalkanes, and acid was added at 0℃~5℃ to carry out a continuous polycondensation reaction to obtain branched aromatic copolymers.

5. The method for preparing branched aromatic copolymers according to claim 4, characterized in that, The molar ratio of the biaryl compound to the piperidinone is 1:1 to 2; The molar ratio of the biaryl compound to 2,4,6-tris(4-(9,9'-spirocyclic[fluorene]-2-yl)phenyl)-1,3,5-triazine is 1:0.01 to 1.

6. The method for preparing the branched aromatic copolymer according to claim 4, characterized in that, The biaryl compound is biphenyl or para-terphenyl; the piperidinone is N-methyl-4-piperidinone.

7. The method for preparing branched aromatic copolymers according to claim 4, characterized in that, The molar ratio of biaryl compounds to acids is 1:8 to 12.

8. The method for preparing branched aromatic copolymers according to claim 4, characterized in that, The acids are trifluoroacetic acid and trifluoromethanesulfonic acid; the molar ratio of trifluoroacetic acid to trifluoromethanesulfonic acid is 1:10; the halogenated hydrocarbons are dichloromethane or 1,2-dichloroethane.

9. An anion exchange membrane, characterized in that, The anion exchange membrane is obtained by quaternizing the branched aromatic copolymer described in claim 1 or 2, forming a film, and then subjecting it to hydroxide ion exchange treatment by immersion in alkaline solution.

10. The ion exchange membrane according to claim 9, characterized in that, The specific preparation method is as follows: The branched aromatic copolymer was dissolved in a solvent, iodomethane was added, and the reaction was carried out under light-protected conditions to obtain the quaternized polymer. The quaternized polymer is dissolved in a solvent, cast onto a substrate, dried to form a film, and then immersed in an alkaline solution for ion exchange to obtain an anion exchange membrane. The ratio of branched aromatic copolymer to iodomethane is 1.0 g: 0.5 mL to 1 mL; the alkaline solution is KOH solution or NaOH solution.

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