Preparation method of copolymerization type anionic membrane material

Abstract

The invention belongs to the technical field of anionic high-molecular polymer membrane materials, and discloses a preparation method of a copolymerization type anionic membrane material. An aromatic ring structure monomer and a 2-(4-bromobutyl)-4-(trifluoromethyl) acetophenone monomer are used as raw materials to prepare a copolymerization type anionic membrane material; according to the preparation method, due to the existence of a benzene ring, the position of a functional group is far away from a main chain, so that the influence of steric hindrance and a nucleophilic reagent is reduced, the degradation risk is reduced, the long-term stability of the membrane is improved, and the service life of the membrane under severe working conditions is prolonged; and on the other hand, the introduction of a hydrophobic benzene ring also promotes the formation of microphase separation, and meanwhile, the butyl side chain with moderate length also reduces the excessive hydrophilicity in the heptanone structure to a certain extent, so that the problem of balancing between swelling and conductivity is solved.

Description

Technical Field

[0001] This invention relates to the field of anion polymer membrane materials technology, and more particularly to a method for preparing copolymer anion membrane materials. Background Technology

[0002] Hydrogen is a key carrier in the global energy transition and the achievement of carbon emission reduction targets, and its long-term sustainability depends on the large-scale production of green hydrogen (i.e., hydrogen from renewable energy sources). Among various hydrogen production methods, water electrolysis driven by renewable energy is considered the most promising green hydrogen production route due to its low-carbon operating cycle and near-zero emissions. Proton exchange membrane electrolysis (PEMWE) technology is relatively mature, with advantages such as fast dynamic response and high hydrogen purity. However, its high dependence on precious metal catalysts (such as platinum group metals) and high system cost greatly limit its large-scale application. In contrast, anion exchange membrane electrolysis (AEMWE) does not require precious metal catalysts, has greater potential for large-scale deployment, and also has more advantageous oxygen evolution reaction (OER) kinetics.

[0003] Anion exchange membranes are the core functional components of the AEMWE system, serving to both block gas permeation and conduct hydroxide ions (OH⁻). Their long-term chemical stability in alkaline environments directly determines the durability and performance of the electrolysis unit. Excellent membrane materials require good ionic conductivity, dimensional stability, high oxidation stability, and low cost. Currently, commercially available Nafion membranes suffer from low hydrogen production efficiency due to water migration, and their high production costs make them unsuitable for large-scale industrial use. Therefore, researching anion exchange membranes that combine excellent electrical performance with low cost has become a hot topic for promoting the further development of hydrogen production through water electrolysis. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention proposes a method for preparing copolymer anion exchange membrane materials.

[0005] The technical solution of the present invention is as follows: A method for preparing a copolymeric anion exchange membrane material, using aromatic ring structure monomers and 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone monomers as raw materials; comprising the following steps:

[0006] Step 1: Mixing raw materials;

[0007] Step 1.1: Dissolve p-terphenyl, aromatic ring structure monomer and 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone monomer as raw materials in dichloromethane, and perform mechanical stirring or magnetic stirring to obtain a homogeneous solution;

[0008] Step 1.2: Add the catalyst to the homogeneous solution to react and obtain a viscous liquid;

[0009] Step 2: Precipitation of reactants;

[0010] Step 2.1: Add precipitant A to the viscous liquid to obtain filamentous solid precipitate or powdery precipitate; wash the filamentous solid precipitate or powdery precipitate alternately with precipitant A and deionized water until neutral;

[0011] Step 2.2: Dry and pulverize the filamentous solid precipitate or powdered precipitate to obtain the polymer material;

[0012] Step 3: Functional group modification;

[0013] Step 3.1: At room temperature, dissolve the polymer material in a polar organic solvent and stir electromagnetically until homogeneous to obtain a polymer solution;

[0014] Step 3.2: After adding functional group monomers to the polymer solution, magnetic stirring is performed at 50℃-130℃ to obtain anionic polymers containing different functional group structures;

[0015] Step 3.3: Add the functional group-modified anionic polymer solution to precipitant B to obtain a precipitate, and perform post-treatment to obtain a dry anionic polymer;

[0016] Step 4: Prepare the polymer electrolyte membrane;

[0017] Step 4.1: Under magnetic stirring, the dried anionic polymer is fully dissolved in an organic solvent to obtain a functionalized polymer solution;

[0018] Step 4.2: The functionalized polymer solution is prepared into a membrane material by solution casting. Specifically, the functionalized polymer solution is dried and volatilized on a petri dish to obtain a copolymer anionic polymer membrane material.

[0019] The para-terphenyl is of Formula 1; the aromatic ring monomer is at least one of Formulas 2-6; the 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone monomer is of Formula 7; and the functional group monomer is at least one of Formulas 8-16.

[0020] .

[0021] Step 1 corresponds to reaction A; Step 3 corresponds to reaction B, as shown below;

[0022] .

[0023] In the said Reaction A, the molar ratio of p-terphenyl to the aromatic ring structure monomer participating in Reaction A is 1 - n:n, where 0 < n ≤ 1; in Reaction B, the molar amount of R1 added is 6 - 10 times the molar amount of the product of Reaction A.

[0024] In Step 1.1, the mass ratio of the raw material substance to dichloromethane is 5% - 20%.

[0025] The mechanical stirring or magnetic stirring in Step 1.1 is carried out in an ice bath or at room temperature.

[0026] In Step 1.2, the catalyst is trifluoromethanesulfonic acid; the addition amount of the catalyst accounts for a proportion greater than 20% and less than 80% of the total volume of the catalyst and dichloromethane;

[0027] After reacting for 20 min under ice bath conditions in Step 1.2, continue to react for 1 h - 5 h at room temperature, and both reactions are carried out under stirring conditions.

[0028] The precipitating agent A is one or more of methanol, sodium carbonate, sodium bicarbonate, potassium carbonate solution, and the concentration of the precipitating agent A is 1 mol / L - 2 mol / L; the total addition amount of the precipitating agent A is not less than 5 times the volume of the viscous liquid;

[0029] In Step 2.2, the drying temperature is 20°C - 50°C, and the drying time is 7 h - 24 h.

[0030] In Step 3.1, the polar organic solvent is one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide; the mass ratio of the polymer material to the polar organic solvent is 1:(50 - 100);

[0031] The precipitating agent B is at least one of methanol, ethyl acetate, isopropanol, and ether.

[0032] In Step 4.1, the organic solvent is dimethyl sulfoxide; in Step 4.2, the oven temperature during film formation is 60°C - 80°C.

[0033] Advantages of 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone: Compared to the existing heptanone structure, the most prominent advantage of this structure is its simple synthesis steps and low production cost, which meets the requirements for low-cost large-scale mass production. Secondly, due to the addition of a rigid benzene ring, on the one hand, this rigid structure and the flexible alkyl chain work together to give the membrane better mechanical properties. The presence of the benzene ring keeps the functional groups away from the main chain, thereby reducing steric hindrance and the influence of nucleophiles, reducing the risk of degradation, improving the long-term stability of the membrane, and thus extending the service life of the membrane under harsh working conditions. On the other hand, the introduction of the hydrophobic benzene ring also promotes the formation of microphase separation, while the moderately long butyl side chain also reduces the excessive hydrophilicity in the heptanone structure to a certain extent, thus solving the trade-off between swelling and conductivity.

[0034] The beneficial effects of this invention are as follows:

[0035] 1. The polymer membrane prepared by this invention has polymer monomers with different structures copolymerized on its main chain, giving it good water absorption and dimensional stability;

[0036] 2. This invention connects different functional group structures to the side chain structure, thereby ensuring that the membrane has good anionic conductivity and electrochemical performance;

[0037] 3. The materials used in this invention are readily available, inexpensive, and the reaction conditions are mild. Attached Figure Description

[0038] Figure 1 This is a graph showing the conductivity data of the anion exchange polymer films obtained in Examples 1-2 at 30-80°C. The vertical axis represents conductivity (mS·cm). -1 );

[0039] Figure 2 This is the tensile diagram of the corresponding polymer film. Detailed Implementation

[0040] This invention proposes a method for preparing copolymeric anion exchange membrane materials, involving a process for preparing copolymeric polymer electrolyte membranes containing a 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone structure. This provides a new approach for developing low-cost, high-performance ion exchange membranes, offering advantages such as simple preparation method, low cost, high proton conductivity, and excellent mechanical properties. This invention uses carbonyl-containing 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone monomer and aromatic ring structure monomers under superacid catalysis and functional group modification to synthesize a series of polymer membranes with different structures. These polymer membranes are then applied to AEMs (Alternating Electrolyte Membranes). The prepared polymer electrolyte membranes are homogeneous, transparent, and structurally dense copolymeric anion exchange membrane materials.

[0041] Example 1

[0042] The steps for preparing the terphenyl-acetophenone-furan-trimethylamine copolymer film are as follows:

[0043] The polymerization procedure for p-terphenyl and aromatic ring monomer formula 5 with functional group formula 8 is as follows:

[0044] (1) First, terphenyl, furan, and 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone were mixed and dissolved in dichloromethane solvent (2 ml) to form the reaction solution. The molar ratio was terphenyl:furan:2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone = 1-n:n:1.1 (the ratio is 0.3:0.7:1.1 in this example). The mixed solution was magnetically stirred at room temperature for 10 min to obtain a homogeneous solution. Trifluoromethanesulfonic acid (0.8 ml) was added to the reaction solution under ice bath conditions. After 10 min, the ice bath was removed, and the reaction was continued for 3 h until viscosity appeared, forming a viscous liquid.

[0045] (2) The viscous liquid was poured into a methanol solution for precipitation and soaking, crushed and soaked in methanol solution again, and dried in a constant temperature oven at 40°C for 8 hours to obtain the corresponding polymer material;

[0046] (3) Trimethylamine polymer membrane: The polymer was dissolved in N,N-dimethylacetamide under magnetic stirring, and functional group 8 was added to form a grafting reaction solution with a molar ratio of polymer: monomer 8 = 1:8. The mixture was magnetically stirred at 50°C for 48 hours.

[0047] (4) The grafted polymer solution after the reaction was completed was added dropwise to methanol for precipitation and soaking, and finally dried in a constant temperature oven at 40℃ for 24 hours to obtain the corresponding anionic polymer.

[0048] (5) Under normal temperature conditions, a certain mass of polymer was weighed and dissolved in dimethyl sulfoxide to obtain a polymer mixed solution with a mass fraction of 2%. The polymer mixed solution was electromagnetically stirred to obtain a homogeneous solution, which was then poured into a clean petri dish. The solvent was evaporated at 80°C, and the film formation time was 15-24 hours. After the solvent was completely evaporated, a homogeneous membrane was obtained. The obtained copolymer anionic polymer membrane material has excellent proton conductivity and mechanical properties, and the conductivity at 80°C is 64.58 mS·cm. -1 .

[0049] Example 2

[0050] The steps for preparing the terphenyl-acetophenone-thiophene-trimethylamine copolymer film are as follows:

[0051] The polymerization procedure for p-terphenyl and aromatic ring monomer 3 is as follows:

[0052] (1) First, terphenyl, thiophene, and 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone are mixed and dissolved in dichloromethane solvent (1.5 ml) to form the reaction solution. The molar ratio is terphenyl:thiophene:2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone = 1-n:n:1.1 (the example ratio here is 0.5:0.5:1.1). The mixture is mechanically stirred evenly under ice bath conditions. Trifluoromethanesulfonic acid (0.6 ml) is added to the reaction solution, and the reaction is continued for 3 hours until viscosity is reached, forming a viscous liquid.

[0053] (2) The viscous liquid was poured into a methanol solution for precipitation and soaking, crushed and soaked in methanol solution again, and dried in a constant temperature oven at 40°C for 8 hours to obtain the corresponding polymer material;

[0054] (3) Dissolve the polymer material in N,N-dimethylacetamide DMAc under magnetic stirring, add functional group 8 to form a grafting reaction solution with a molar ratio of polymer:monomer 8 = 1:8, and stir magnetically at 50°C for 48 hours.

[0055] (4) The grafted polymer solution after the reaction was completed was added dropwise to methanol for precipitation and soaking, and finally dried in a constant temperature oven at 40℃ for 24h to obtain the corresponding anionic polymer;

[0056] (5) Under normal temperature conditions, a certain mass of anionic polymer was weighed and dissolved in dimethyl sulfoxide to obtain a polymer mixed solution with a mass fraction of 2%. The polymer mixed solution was electromagnetically stirred to obtain a homogeneous solution, which was then poured into a clean petri dish. The solvent was evaporated at 80°C, and the film formation time was 15-24 hours. After the solvent was completely evaporated, a homogeneous membrane was obtained. The copolymer anionic membrane has excellent proton conductivity and mechanical properties, and its conductivity at 80°C is 56.76 mS·cm. -1 .

[0057] Example 3

[0058] Preparation of the terphenyl-acetophenone-diphenyl-trimethylamine membrane: A polymer was synthesized from p-terphenyl, diphenyl, and 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone using a catalyst, with the remaining steps being the same as in Example 1; finally, a trimethylamine functional group was attached to its side chain. The conductivity of this copolymeric anion exchange membrane can reach 60 mS·cm. -1 .

[0059] Example 4

[0060] Preparation of the terphenyl-phenoxyethylene-methylimidazole membrane: A copolymer of p-terphenyl, phenoxyethylene, and 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone was formed by reaction. The polymer was then functionalized with methylimidazole. The remaining steps were the same as in Example 1. The resulting copolymer anion exchange membrane, terphenyl-phenoxyethylene-methylimidazole, had a conductivity of 52.4 mS·cm. -1 .

[0061] Example 5

[0062] Preparation of the terphenyl-butadiene-piperidineamine membrane: The polymer formed by the catalytic reaction of terphenyl, butadiene, and 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone at room temperature was functionalized with a piperidineamine compound, and the remaining steps were the same as in Example 1; the conductivity of the obtained copolymer anionic membrane can reach up to 70 mS·cm. -1 .

[0063] The anionic conductivity and mechanical properties of the relevant polymer films in Examples 1-2 are as follows: Figures 1-2 As shown, compared to heptanone with long side chains and no rigid benzene ring structure, 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone polymer films containing a rigid benzene ring structure exhibit higher electrical conductivity and superior mechanical properties.

Claims

1. A method for preparing a copolymeric anion exchange membrane material, characterized in that, Using aromatic ring structure monomers and 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone monomers as raw materials; including the following steps: Step 1: Mixing of raw material substances; Step 1.1: Dissolve p-terphenyl, aromatic ring structure monomers and 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone monomers as raw material substances in dichloromethane, and conduct mechanical stirring or magnetic stirring to obtain a homogeneous solution; Step 1.2: Add a catalyst to the homogeneous solution for reaction to obtain a viscous liquid; Step 2: Precipitation of reactants; Step 2.1: Add precipitant A to the viscous liquid to obtain a filamentous solid precipitate or a powdery precipitate; Wash the filamentous solid precipitate or the powdery precipitate alternately with precipitant A and deionized water until neutral; Step 2.2: Dry and crush the filamentous solid precipitate or the powdery precipitate to obtain a polymer material; Step 3: Functional group modification; Step 3.1: At room temperature, dissolve the polymer material in a polar organic solvent, and stir magnetically to dissolve it evenly to obtain a polymer solution; Step 3.2: After adding functional group monomers to the polymer solution, conduct magnetic stirring at 50°C - 130°C to obtain an anionic polymer containing different functional group structures; Step 3.3: Add the functional group-modified anionic polymer solution to precipitant B to obtain a precipitate, and conduct post-treatment to obtain a dry anionic polymer; Step 4: Preparation of a polymer electrolyte membrane; Step 4.1: Under magnetic stirring, fully dissolve the dry anionic polymer in an organic solvent to obtain a functionalized polymer solution; Step 4.2: Use the solution casting method to prepare the functionalized polymer solution into a membrane material, specifically by drying and volatilizing the functionalized polymer solution on a petri dish to obtain a copolymeric anionic polymer membrane material.

2. The method for preparing copolymeric anion exchange membrane material according to claim 1, characterized in that, The p-terphenyl is of formula 1, the aromatic ring structure monomer is at least one of formula 2 - formula 6; the 2-(4-bromobutyl)-4-(trifluoromethyl)acetophenone monomer is of formula 7; the functional group monomer is at least one of formula 8 - formula 16; 。 3. The method for preparing the copolymeric anion exchange membrane material according to claim 1, characterized in that, Step 1 corresponds to reaction A; Step 3 corresponds to reaction B; as follows:

4. The method for preparing the copolymeric anion exchange membrane material according to claim 3, characterized in that, In the reaction A, the molar ratio of p-terphenyl to the aromatic ring structure monomer participating in reaction A is 1 - n:n, 0 < n ≤ 1; in reaction B, the molar amount of R1 added is 6 - 10 times the molar amount of the product of reaction A.

5. The method for preparing the copolymeric anion exchange membrane material according to claim 1, characterized in that, In Step ①, the mass ratio of the raw material substances to dichloromethane is 5% - 20%.

6. The method for preparing the copolymeric anion exchange membrane material according to claim 1, characterized in that, The mechanical stirring or magnetic stirring in Step 1.1 is carried out in an ice bath or at room temperature.

7. The method for preparing the copolymeric anion exchange membrane material according to claim 1, characterized in that, In Step 1.2, the catalyst is trifluoromethanesulfonic acid; the addition amount of the catalyst accounts for more than 20% and less than 80% of the total volume of the catalyst and dichloromethane; After reacting in an ice bath condition for 20 min in Step 1.2, continue to react at room temperature for 1 h - 5 h, and both reactions are carried out under stirring conditions.

8. The method for preparing the copolymeric anion exchange membrane material according to claim 1, characterized in that, The precipitant A is one or more of methanol, sodium carbonate, sodium bicarbonate, potassium carbonate solution, and the concentration of the precipitant A is 1 mol / L - 2 mol / L; the total addition amount of the precipitant A is not less than 5 times the volume of the viscous liquid; In step 2.2, the drying temperature is 20℃-50℃ and the drying time is 7h-24h.

9. The method for preparing the copolymeric anion exchange membrane material according to claim 1, characterized in that, In step 3.1, the polar organic solvent is one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide; the mass ratio of the polymer material to the polar organic solvent is 1:(50-100). The precipitant B is at least one of methanol, ethyl acetate, isopropanol, and diethyl ether.

10. The method for preparing the copolymeric anion exchange membrane material according to claim 1, characterized in that, In step 4.1, the organic solvent is dimethyl sulfoxide; in step 4.2, the oven temperature during film formation is 60℃-80℃.

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