Anion exchange membrane, preparation method thereof and application thereof

Abstract

The present invention relates to the technical field of polymer materials, and particularly relates to an anion exchange membrane, a preparation method and an application thereof. The anion exchange membrane is formed by an ion exchange polymer copolymerized from a thiophene-based main chain monomer and a trifluoroalkyl compound side chain monomer. The ratio of thiophene groups to phenyl groups in the main chain monomer is fixed. Through precise doping copolymerization of thiophene groups, the present invention introduces sulfur-sulfur interactions between the main chain skeletons, thereby changing the gas and water diffusion properties of the material. It can increase the flexibility of the main chain while improving the conductivity. The application of such polymers in anion exchange membranes realizes the comprehensive regulation of mechanical properties and ion conduction properties. The structural characteristics of the obtained polymer main chain without ether bonds and unsaturated bonds can improve the alkali resistance stability of the anion exchange membrane, and are suitable for the recovery treatment of industrial wastewater containing dyes such as eosin B (EB) and reactive red X-3B.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to an anion exchange membrane, a preparation method thereof, and an application thereof. Background Art

[0002] As an emerging technology, the anion exchange membrane electrolyzer (AEME) has many potential advantages in terms of cost and large-scale application compared with the proton exchange membrane electrolyzer (PEME) technology. An AEME is usually composed of a bipolar plate and a membrane electrode assembly. Among them, the membrane electrode assembly (MEA) is the place for electrochemical reactions and is a key component determining the performance of the electrolyzer. It is usually composed of an anion exchange membrane (AEM), an ionomer, an anode, a cathode catalyst layer, and a porous layer. The AEM plays a crucial role in the overall performance and durability of the electrolyzer.

[0003] The anion exchange membrane is made from anion exchange resins by methods such as casting and blade coating. Existing anion polymers can be classified into the following categories according to the backbone structure: polyphenylene ether-based, polysulfone-based, polyether ether ketone-based, polystyrene-based, polyethylene rigid backbone-based, tröger's base-based polymers, poly(bi)aryl and trifluoromethyl ketone-based copolymers, polyarylpiperidine-based, etc. Among them, the first three categories are prone to degradation in an alkaline environment due to the presence of unsaturated bonds or oxa bonds in the main chain backbone, and the material stability is poor; the 4th, 5th, and 6th categories of polyethylene-derived backbones have poor conductivity performance, and the solubility of the products decreases after the molecular weight increases, and the corresponding film-forming processability becomes worse; the last two categories of polymer backbones are two materials developed recently.

[0004] The conductivity performance of the anion exchange membrane is mainly determined by the transport performance of ionic groups (head-group) on the side chain groups. While the polymer backbone determines the mechanical properties of the membrane, it also greatly affects the gas and water diffusion properties of the membrane.

[0005] Patent CN113801352A provides a preparation method of a crosslinked anion exchange membrane mainly composed of polyarylpiperidine. Using biphenyl and terphenyl monomers as raw materials, a hydroxyalkylation reaction is carried out with piperidone under the catalysis of superacid to obtain polyarylpiperidine. Then, the polymer is functionalized with piperidine on the polymer molecular chain using iodomethane as a functionalizing reagent. Finally, an alkyl dibromide is used as a crosslinking agent to achieve crosslinking at the N atom position. The conductivity of the prepared anion exchange membrane is relatively low, and the conductivity at 80 °C is basically about 100 mS / cm, and toxic iodomethane is used.

[0006] CN116856004A discloses a quaternary ammonium polybiphenylene anion exchange membrane for producing hydrogen by electrolysis of water using anion exchange membrane and a preparation method thereof. The main chain of the polybiphenylene is obtained by subjecting biphenyl to a Friedel-Crafts hydroxyalkylation reaction with 7-bromo-1,1,1-trifluoroheptane-2-one and 2,2,2-trifluoroacetophenone; the obtained polybiphenylene is dissolved and reacted with trimethylamine, pyridine and N-methylpiperidine to obtain corresponding ionomers, thereby successfully preparing a quaternary ammonium polybiphenylene anion exchange membrane for producing hydrogen by electrolysis of water having both high ionic conductivity and strong alkali resistance and stability. However, the flexibility of the membrane is relatively poor.

[0007] The skeleton of the current poly(bi)biphenyl and trifluoromethyl ketone copolymer anion exchange membrane materials mainly contains benzene rings. This type of structure is relatively rigid, and the interaction between the main chains is mainly van der Waals force. The interaction between the polymer and the catalyst is also limited to this, and the flexibility of the membrane is relatively poor. At the same time, when this type of material is used as a catalyst layer adhesive, the diffusion of gas and water is greatly affected, resulting in poor conductivity of the anion exchange membrane. Therefore, it is becoming increasingly urgent to provide a material that improves the mechanical properties while changing the ion conductivity of the membrane by adjusting the skeleton structure of the polymer. Summary of the invention

[0008] In order to solve the problem that the conductivity and flexibility of existing compounds cannot be taken into account at the same time, the present invention provides an anion exchange membrane and a preparation method and application thereof.

[0009] An anion exchange membrane is formed by copolymerizing an ion exchange polymer of a thiophene main chain monomer and a trifluoroalkyl compound side chain monomer, and the structure of the ion exchange polymer is:

[0010] ;

[0011] Wherein, x is an integer of 1-5, y is an integer of 1-5, z is an integer of 1-5, m is an integer of 1-3, and the ratio of thienyl to phenyl in the main chain monomer is fixed.

[0012] Furthermore, the general structural formula of the main chain monomer is as shown in Formula I or Formula II:

[0013] ;

[0014] Wherein, the aromatic group Ar is selected from any one of the following monomers containing a phenyl structure:

[0015] ;

[0016] R is selected from any one of the following monomers containing a thiophene group:

[0017] 。

[0018] Further, the aromatic groups Ar on both sides of the thiophene group in Formula I are the same group.

[0019] Further, the aromatic groups Ar on both sides of the thiophene group in Formula I are different groups.

[0020] Further, the thiophene group in Formula II is located at any site of the aromatic group Ar.

[0021] Further, the general formula of the branched-chain monomer of the trifluoroalkyl compound is CF3CO-(CH2) m -X, where X is Cl or Br, and m = 1 - 3.

[0022] Further, a method for preparing an anion exchange membrane is also provided. The steps are main chain monomer synthesis → polymer formation → polymer ionization → membrane preparation and post-treatment. The ion exchange polymer is prepared by polymerizing a main chain monomer and a branched-chain monomer under the action of trifluoromethanesulfonic acid. The ratio of the main chain monomer to the branched-chain monomer is 1:1;

[0023] Among them, the trifluoromethanesulfonic acid needs to be added dropwise at 0 - 4 °C, and the temperature in the system is controlled ≤ 10 °C during the dropping process.

[0024] Further, the synthesis steps of the main chain monomer of the polymer are as follows:

[0025] (1) Bromination: The thiophene-based compound and the bromination reagent react in a molar ratio of 1:(2 - 4) to obtain a thiophene-based brominated compound. Among them, the thiophene-based compound is thiophene, bithiophene or terthiophene, and the bromination reagent is NBS;

[0026] (2) Coupling: The thiophene-based brominated compound obtained in step (2) and the aromatic compound are doped by a coupling reaction in a doping molar ratio of 1:(2 - 4) to obtain the main chain monomer. The aromatic compound is phenylboronic acid or biphenylboronic acid.

[0027] Further, the polymer ionization process is to carry out an ionization reaction on the polymer under the action of a quaternary ammonium salt to form an ion exchange polymer. Among them, the quaternary ammonium salt is a 30% aqueous solution of trimethylamine, and the ratio of the polymer to the quaternary ammonium salt is 1:(2 - 20); the process of membrane preparation and post-treatment is to completely replace Br- on the membrane with OH- after making the ion exchange polymer into a finished membrane to obtain the anion exchange membrane.

[0028] The anion exchange membrane described in the present invention is applicable to the recovery treatment equipment for industrial wastewater containing eosin B type and reactive red X-3B type dyes.

[0029] The advantages of the present invention are as follows:

[0030] The present invention provides an anion exchange polymer with a copolymerized main chain doped with thiophene groups, introducing sulfur-sulfur interactions between the main chain skeletons, thereby changing the gas and water diffusion properties of the material, increasing the main chain flexibility while improving the conductivity, and enhancing the tensile properties of the membrane;

[0031] At the same time, by precisely controlling the amounts of thiophene groups and aromatic groups, the obtained anion exchange membrane has an orderly structure arrangement, improving the mechanical properties and ionic conductivity of the membrane material. The structural characteristics of the obtained polymer main chain without ether bonds and unsaturated bonds can also enhance the alkali resistance stability of the anion exchange membrane;

[0032] By controlling the feeding amount of the main chain monomers, the utilization rate of the reaction raw materials is close to 100%, achieving comprehensive regulation of the mechanical properties and ionic conduction properties of the anion exchange membrane while saving energy and protecting the environment, and obtaining an anion exchange membrane with excellent performance. Brief Description of the Drawings

[0033] Figure 1 is the nuclear magnetic resonance hydrogen spectrum of intermediate 1-bromobithiophene in Example 1 of the present invention;

[0034] Figure 2 is the nuclear magnetic resonance hydrogen spectrum of the monomer compound after coupling bithiophene and aromatic groups in Example 1 of the present invention;

[0035] Figure 3 is the nuclear magnetic resonance hydrogen spectrum of the ion-exchange polymer with a main chain doped with bithiophene after ionization in Example 1 of the present invention;

[0036] Figure 4 is a physical picture of the anion exchange membrane prepared in Example 1 of the present invention;

[0037] Figure 5 is the adsorption effect picture of the anion exchange membrane prepared in Example 1 of the present invention;

[0038] Figure 6 is the adsorption percentage change graph of the anion exchange membrane prepared in Example 1 of the present invention at different temperatures. Detailed Embodiments

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0040] It should be noted that all the installation methods and technical terms mentioned in the present invention are technical terms that are already well-known in the relevant technical field, so no further explanation will be given. In addition, the same reference numerals are used for the same components, but this does not affect and should not constitute an inaccurate understanding of the technical solution by those skilled in the art.

[0041] Example 1. This example provides an anion exchange membrane formed by an ion exchange polymer with a main chain doped with bithiophene. Its preparation process includes main chain monomer synthesis → polymer formation → polymer ionization → membrane preparation and post-treatment. The specific steps are as follows:

[0042] (1) Preparation of the monomer with a main chain doped with bithiophene:

[0043] Step 1 (bromination): Wrap the outside of the three-necked flask with tin foil for light shielding. Under nitrogen protection, add 10.00 g of bithiophene and 100 mL of dichloromethane to the three-necked flask in sequence. Add 23.14 g of NBS under stirring, and stir at room temperature for 5 h. Monitor by TLC.

[0044] Step 2: After monitoring the reaction by TLC and determining it is complete, add 50 mL of water to the reaction system in Step 1 for liquid separation; back-extract the aqueous phase with dichloromethane, combine the organic phases and concentrate to dryness, and perform solid column chromatography to obtain Intermediate 1 (brominated bithiophene, the 1H NMR spectrum is as Figure 1 shown).

[0045] Step 3 (coupling): Under nitrogen protection, add 5.00 g of Intermediate 1 obtained in Step 2, 4.14 g of phenylboronic acid, and 10V of ultra-dry THF to the three-necked flask in sequence, keep stirring, evacuate and replace the gas three times, then under nitrogen protection, add 0.18 g of palladium catalyst (the palladium catalyst in this example is Pd(PPh3)4) and 2 mL of 2M potassium carbonate solution to the three-necked flask, evacuate and replace the gas twice, control the temperature at 50 - 70 °C and react for 10 h. After monitoring the reaction by TLC and determining it is complete, cool to room temperature.

[0046] Step 4: After cooling to room temperature, pour the reaction system in Step 3 into methanol (650 mL, 10V). After yellow solid precipitates, filter out the solid, dissolve it and perform column chromatography to obtain the main chain monomer product (the 1H NMR spectrum is as Figure 2 shown).

[0047] (2) Preparation of the polymer:

[0048] Step 5 (Copolymerization): Under nitrogen protection, add 76.20 mL of dichloromethane to a three-necked flask. While stirring, sequentially add 20.73 g of the branched monomer (the branched monomer in this example is 7-bromo-1,1,1-trifluoroheptan-2-one), and 12.21 g of the main chain monomer obtained in Step 4. Stir at room temperature until the system is completely dissolved. Place the three-necked flask in an ice-water bath, cool the system to 0 - 4 °C, and control the temperature to dropwise add trifluoromethanesulfonic acid. During the dropping process, keep the internal temperature of the system below 10 °C. After the addition of trifluoromethanesulfonic acid is complete, slowly raise the reaction system to 25 °C and stir at 25 °C for 18 hrs;

[0049] Step 6: Slowly pour the reaction system in Step 5 into ethanol (650 mL, 10V). Yellow fibrous solids will precipitate. Filter out the solids and dry them in a vacuum drying oven. Set the temperature of the vacuum drying oven to 70 °C and dry for 24 hrs;

[0050] Step 7: Thoroughly grind the dried solid in Step 6, then wash and filter it three times with ethanol (650 mL, 10V) until the pH of the final filtrate is 6 - 7. Dry the solid again to obtain the ion exchange polymer;

[0051] (3) Polymer ionization (formation of ion exchange polymer):

[0052] Step 8 (Ionization): Add THF (100 ml) and the dried ion exchange polymer (10.00 g) obtained in Step 7 to a three-necked flask. Raise the temperature of the system to 25 °C and stir until all the solids are dissolved. Add 30% aqueous trimethylamine solution (TMA) (17.33 g, 5.0 eq) to the three-necked flask. After 6 hrs, add deionized water. After 22 hrs, add the solution in the bottle to a beaker containing 1.5 L of isopropanol while stirring. The system changes from a liquid to an elastic solid state;

[0053] Step 9: After filtering the elastic solid state system obtained in Step 8, place it in a vacuum drying oven to dry. Set the oven temperature to 80 °C and dry for 24 hrs to obtain the ionized ion exchange polymer with the main chain doped with bithiophene (the proton nuclear magnetic resonance spectrum is as Figure 3 shown).

[0054] The structure of the main chain monomer doped with bithiophene is as follows:

[0055]

[0056] The structure of the ionized ion exchange polymer with the main chain doped with bithiophene is as follows:

[0057] ;

[0058] The reaction equation is as follows:

[0059] ;

[0060] (4) Preparation and post-treatment of the anion exchange membrane:

[0061] 1) Take 5 g of the ion exchange polymer with the main chain doped with bithiophene, dissolve it in 20 mL of DMSO, keep magnetic stirring, and heat at 80 °C to obtain a mixed solution;

[0062] 2) Pour the mixed solution obtained in step 1) onto a heating table and heat and dry it at 70 °C to obtain a finished film;

[0063] 3) Immerse the finished film obtained in step 2) in 1 M KOH aqueous solution for 12 h to ensure that the Br - is completely replaced by OH - , and wash it with deionized water to obtain the corresponding anion exchange membrane (the physical picture of the membrane is as shown in Figure 4 ).

[0064] Example 2 This example provides an anion exchange membrane formed from an ion exchange polymer with the main chain doped with thiophene. Its preparation process is the same as that of Example 1, except that in the bromination reaction of this example, thiophene is used as the reaction raw material, and the ratio of thiophene to the bromination reagent is 1:1.5; in the coupling reaction of this example, the palladium catalyst used is Pd(dtbpf)Cl2, and the structure of the obtained main chain monomer is:

[0065] ;

[0066] In the polymerization reaction of this example, the ratio of the main chain monomer to the branched chain monomer is: 1:1.2, and the structure of the ionized polymer with the main chain doped with thiophene after ionization is:

[0067] .

[0068] Example 3 This example provides an anion exchange membrane formed from an ion exchange polymer with the main chain doped with terthiophene. Its preparation process is the same as that of Example 1, except that in the bromination reaction of this example, thiophene is used as the reaction raw material, and the ratio of thiophene to the bromination reagent is 1:2.5, and the structure of the obtained main chain monomer is:

[0069] ;

[0070] In the polymerization reaction of this example, the ratio of the main chain monomer to the branched chain monomer is: 1:1.2, and the structure of the ionized polymer with the main chain doped with terthiophene after ionization is:

[0071] .

[0072] Comparative Example 1

[0073] Using biphenyl as the main chain monomer and 7-bromo-1,1,1-trifluoroheptan-2-one as the side chain monomer, prepared according to the preparation method of Example 1 above, an anion exchange membrane formed by an ionized polymer with an undoped thiophene group in the main chain was obtained. Among them, the structure of the ionized polymer with an undoped thiophene group in the main chain is as follows:

[0074]

[0075] Test Experiment 1:

[0076] The mechanical properties, tensile properties, water absorption swelling rate, and conductivity of the anion exchange membranes obtained in Examples 1-3 were tested respectively. The results are shown in Table 1:

[0077] Before testing, the membrane needs to be pretreated: The anion exchange membrane to be tested needs to be cut into small pieces of 1 cm × 4 cm, soaked in 1 M KOH, keeping the temperature of the KOH solution at 80 °C and the soaking time at 24 h; after soaking, it is thoroughly washed three times with deionized water until the conductivity of the last washing solution is less than 3 μS / cm. Otherwise, it is washed with deionized water again until the conductivity of the washing solution is less than 3 μS / cm.

[0078] The test methods for water absorption rate and swelling rate are as follows:

[0079] Water absorption rate: Weigh the dried membrane, and record the mass as m1; then soak the membrane in deionized water at 25 °C for 24 h, take it out and dry the surface; weigh it again and record the mass as m2; then the water absorption rate is: (m2 - m1) / m1 × 100%;

[0080] Swelling rate: It is calculated by measuring the change in the length of the membrane before and after absorbing the electrolyte. The formula is: Swelling ratio (%) = (Lw - Ld) / Lw × 100%, where Lw and Ld are the lengths of the membrane in the solution-saturated state and the dry state respectively.

[0081] The test method for mechanical properties is as follows:

[0082] Test the anti-tensile deformation ability of the thin film, which is divided into two directions: horizontal and vertical.

[0083] Test according to standards such as ISO 527-3, GB / T 1040.3, ASTM D882, etc.

[0084] Test process: Cut the thin film into a long strip specification, fix the upper and lower ends on the clips of the test instrument respectively, keep one end stationary, and move the other end at a constant speed to stretch the thin film until it breaks completely.

[0085] Data such as secant modulus and breaking tensile strength can be obtained, reflecting the tensile stiffness of the film and the force required for it to be stretched and broken.

[0086] The test method for conductivity is as follows:

[0087] 1. Electrode installation: Install two parallel electrodes on both sides of the membrane material. The electrode material should be non-reactive to avoid chemical reactions with the membrane material.

[0088] 2. Environmental control: Place the membrane material and electrodes in a constant temperature and humidity chamber to ensure the consistency of environmental conditions during the test.

[0089] 3. Voltage application: Apply a known DC voltage to the membrane material through the electrodes.

[0090] 4. Current measurement: Measure the current passing through the membrane material using a high-precision ammeter to ensure the accuracy of the data.

[0091] 5. Conductivity calculation: Calculate the conductivity of the membrane material according to Ohm's law, that is:

[0092] Conductivity (σ) = Current (I) / Voltage (V) × Area (A) / Thickness (d), where A is the cross-sectional area of the membrane material and d is the thickness of the membrane material.

[0093] Table 1 Test result table of examples and comparative examples

[0094]

[0095] The above data shows that: Based on the anion exchange membranes prepared from the thiophene-doped ion exchange polymers in Examples 1-3 of the present invention, the water absorption test results are all <10%, and the swelling rate test results are <12%. These two indicators are significantly better than the anion exchange membranes prepared from non-thiophene-doped polymers in Comparative Example 1. At the same time, the anion exchange membranes prepared from the materials of the present invention still maintain a high tensile strength, and the hydroxide ion conductivity test results of the anion exchange membranes at 80 °C reach above 170 mS / cm, indicating that the mechanical properties of the material are maintained while the conductivity is improved after thiophene doping, showing excellent ion exchange performance, indicating that this material has extremely high potential application value in the field of anion exchange membrane electrolyzers.

[0096] Test experiment 2:

[0097] The ion exchange capacity of the anion exchange membranes prepared in Examples 1-3 was measured by acid-base titration method. The specific test method is as follows:

[0098] First, cut the anion exchange membranes prepared in Examples 1-3 into thin slices of appropriate size, wash them thoroughly with deionized water for 15 min to remove surface impurities, and then put them into an oven to dry to a constant weight. After drying, weigh and record the weight.

[0099] Secondly, soak the dried membrane samples in an excessive amount of concentrated HCl solution and stir at room temperature for 48 h to ensure that the OH - in the anion exchange membrane is completely converted to Cl - . Filter the solution to separate the membrane samples.

[0100] Finally, using phenolphthalein as an acid-base indicator, titrate the remaining HCl solution after filtration with the standardized NaOH solution, record the volume of the NaOH solution consumed at the titration end point, and calculate the ion exchange capacity according to the stoichiometric relationship of acid-base titration.

[0101] The specific calculation formula is as follows:

[0102]

[0103] In the formula, IEC is the ion exchange capacity (meq / g), C1V1 represents the concentration (mol / L) and volume (V) of the concentrated HCl solution, C2V2 represents the concentration (mol / L) and volume (V) of the NaOH solution, and m represents the mass (g) of the dried anion exchange membrane.

[0104] Through the above methods and formulas, the ion exchange capacities of the three membrane materials prepared in Examples 1-3 are all between 1.2-1.5 meq / g, which can effectively achieve the separation and removal of specific anions.

[0105] Test Experiment 3:

[0106] By testing the adsorption capacity of the anion exchange membrane prepared in Example 1, the adsorption capacity of the anion exchange membrane for the specified type of dye in industrial wastewater is obtained. The test method for its adsorption capacity is as follows:

[0107] First, take eosin B dye (also known as eosin B, purchased from Wuhan Kemike Biopharmaceutical Technology Co., Ltd.) and reactive red X-3B dye (purchased from Nanjing Dulai Biotechnology Co., Ltd.) respectively, add water to prepare a series of dye solutions A and B with different mass concentrations (50 mg / L, 100 mg / L, 150 mg / L, 200 mg / L, 300 mg / L), and use a UV-visible spectrophotometer to measure the absorbance at the maximum absorption wavelength and draw a standard curve.

[0108] Secondly, the film was cut into a circular specification to prepare an anion exchange membrane disc, which was washed with deionized water for 15 min to remove surface impurities, then dried in an oven. After drying, the weight was 0.1 g. Subsequently, the membrane was placed in 100 mL of 150 mg / L dye solution A and 100 mL of 150 mg / L dye solution B for constant-temperature oscillating adsorption. The absorbance was measured with a UV spectrophotometer at the maximum absorption wavelength, and the dye concentration in the solution was calculated according to the standard working curve. The equilibrium adsorption capacity of the anion exchange membrane was obtained through the mass change of the dye in the dye solution.

[0109] The calculation formula for the equilibrium adsorption capacity is as follows:

[0110]

[0111] In the formula, q is the equilibrium adsorption capacity (mg / g); C1 is the initial mass concentration of the dye in the dye solution (mg / L); C2 is the mass concentration of the dye in the dye solution after adsorption reaches equilibrium (mg / L); V is the volume of the solution (L); m is the mass of the anion exchange membrane after drying (g).

[0112] The changes in the adsorption capacity at different adsorption times are as Figure 5 shown. It can be seen that the anion exchange membrane prepared in Example 1 reached the adsorption equilibrium at 120 min in the treatment of wastewater containing eosin B dye or reactive red X-3B dye. The maximum adsorption capacity of eosin B was 80 mg / g, and the maximum adsorption capacity of reactive red X-3B was 60 mg / g.

[0113] According to this method, the effects of the anion exchange membrane on the adsorption performance of eosin B dye and reactive red X-3B at different temperatures were tested respectively. The results are as Figure 6 shown. It can be seen that the adsorption percentage decreased with the increase of temperature, but showed a stable overall trend, indicating that in the treatment of wastewater containing dyes, the temperature has little effect on the adsorption process and does not affect the change of the adsorption capacity, which is beneficial to the treatment of dye industrial wastewater at room temperature.

[0114] The above experimental data show that the anion exchange membrane described in the present invention has excellent anion conductivity, chemical stability, mechanical properties and solubility, and at the same time has an adsorption and removal effect on specific ions, and is suitable for use in sewage treatment batteries in special scenarios.

[0115] For those skilled in the art, the present inventive concept is not limited to the details of the above-described exemplary embodiments, and the present inventive concept can be implemented in other specific forms without departing from the spirit or essential features of the present inventive concept. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-limiting. The scope of the present inventive concept is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present inventive concept. Any reference signs in the claims should not be construed as limiting the claims concerned.

[0116] The above are only the preferred embodiments of the present inventive concept and are not intended to limit the present inventive concept. Any minor modifications, equivalent substitutions, and improvements made to the above embodiments based on the technical essence of the present inventive concept shall be included within the protection scope of the technical solution of the present inventive concept.

Claims

1. An anion exchange membrane, characterized in that It is formed by copolymerizing thiophene main chain monomers and trifluoroalkyl compound side chain monomers to form an ion exchange polymer, and the structure of the ion exchange polymer is: ； Wherein, x is an integer of 1-5, y is an integer of 1-5, z is an integer of 1-5, m is an integer of 1-3, and the ratio of thienyl to phenyl in the main chain monomer is fixed.

2. An anion exchange membrane according to claim 1, characterized in that: The general structural formula of the thienyl main chain monomer is shown in Formula I: ； Wherein, the aromatic group Ar is selected from any one of the following monomers containing a phenyl structure: ； R is selected from any one of the following monomers containing a thiophene group: ； The aromatic groups Ar on both sides of the thiophene group in the formula I are the same group or different groups.

3. An anion exchange membrane according to claim 1, characterized in that: The general formula of the trifluoroalkyl compound branched monomer is CF3CO-(CH2) m -X, where X is Br, m=2, 4, 6.

4. A method for preparing an anion exchange membrane according to claim 1, wherein the steps are main chain monomer synthesis → polymer formation → polymer ionization → membrane preparation and post-treatment, characterized in that: The ion exchange polymer is prepared by polymerizing a main chain monomer and a side chain monomer under the action of trifluoromethanesulfonic acid, wherein the ratio of the main chain monomer to the side chain monomer is 1:1; The trifluoromethanesulfonic acid needs to be added dropwise at 0-4°C, and the temperature in the system is controlled to be ≤10°C during the addition process.

5. The method for preparing an anion exchange membrane according to claim 4, characterized in that: The synthesis steps of the main chain monomer are: (1) Bromination: A thiophene-based compound and a brominating agent are subjected to a bromination reaction in a molar ratio of 1:(2-4) to obtain a thiophene-based bromide compound, wherein the thiophene-based compound is thiophene, dithiophene or terthiophene, and the brominating agent is NBS; (2) Coupling: The thienyl bromide compound obtained in step (2) and the aromatic compound are doped by coupling reaction at a doping molar ratio of 1:(2-4) to obtain a main chain monomer, wherein the aromatic compound is phenylboronic acid or biphenylboronic acid.

6. The method for preparing an anion exchange membrane according to claim 4, characterized in that: The polymer ionization process is to ionize the polymer under the action of a 30% trimethylamine aqueous solution to form an ion exchange polymer, wherein the molar ratio of the polymer to trimethylamine is 1: (2-20); the membrane preparation and post-treatment process is to remove the Br on the membrane after the ion exchange polymer is made into a finished membrane - Completely replaced by OH - , to obtain the anion exchange membrane.

7. An application of the anion exchange membrane according to any one of claims 1 to 3, characterized in that: The anion exchange membrane is suitable for recycling industrial wastewater containing eosin B type or reactive red X-3B type dyes.

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