High molecular weight hyperbranched polyarylpiperidine anion exchange membrane, preparation method thereof and application

Abstract

The present invention provides a high molecular weight hyperbranched polyarylpiperidine anion exchange membrane and its preparation method and application, which relate to the field of membrane material technology. The high molecular weight hyperbranched polyarylpiperidine anion exchange membrane provided by the present invention is obtained by self-polymerization of branched monomers or copolymerization of branched monomers with biphenyl monomers and N-methyl-4-piperidone, followed by quaternization. The anion exchange membrane has a free volume greater than that of linear polymers, thereby exhibiting ultrahigh electrical conductivity; the high molecular weight polymer backbone ( M n Greater than 100K) gives it excellent alkali resistance and mechanical strength; at the same time, the anion exchange membrane has a low water absorption and swelling rate and dimensional stability, is suitable for water electrolysis to produce hydrogen and alkaline fuel cells, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of membrane materials, in particular to a high molecular weight hyperbranched polyarylpiperidine anion exchange membrane and a preparation method and application thereof. Background Art

[0002] Anion exchange polymers (ACEPs) possess both anion exchange and anion conduction capabilities and are key materials in devices such as alkaline membrane fuel cells, alkaline water electrolyzers, and electrodialyzers. Ionic conductivity, chemical stability, and mechanical properties are key properties of ACEPs, directly impacting the energy conversion efficiency and lifespan of these devices.

[0003] CN109070022A discloses poly(arylpiperidinium) polymers for use as hydroxide exchange membranes and ionomers. Trifluoroacetophenone monomers are added to biphenyl monomers and N-alkyl-4-piperidone to produce a polymer product with a main chain free of ether bonds. This product is then quaternized using a haloalkane to produce an anion exchange polymer with excellent chemical stability. While this patent demonstrates that the mechanical strength of the anion exchange polymer can be increased and its swelling reduced by varying the ratio of trifluoroacetophenone to biphenyl monomers, the high cost of trifluoroacetophenone monomers makes it unsuitable for large-scale application.

[0004] CN110690487A discloses an anion exchange polymer whose backbone comprises biphenyl, terphenyl, and piperidine quaternary ammonium cation structural units, exhibiting high chemical stability and excellent ionic conductivity, mechanical strength, and anti-swelling properties. Although this patent achieves an oxygen-free backbone structure and prepares an anion membrane with a branched structure by introducing branching points such as triphenylbenzene and grafting with long side-chain ionizing agents, the rigid backbone structure still limits the growth of the polymer's molecular weight.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The first object of the present invention is to provide a high molecular weight hyperbranched polyarylpiperidine anion exchange membrane to solve the above technical problems.

[0007] The second object of the present invention is to provide a method for preparing the high molecular weight hyperbranched polyarylpiperidine anion exchange membrane.

[0008] The third object of the present invention is to provide the use of the above-mentioned high molecular weight hyperbranched polyarylpiperidine anion exchange membrane in the preparation of alkaline water electrolysis materials or alkaline fuel cell materials.

[0009] In order to achieve the above objectives, the following technical solutions are adopted:

[0010] In a first aspect, the present invention provides a high molecular weight hyperbranched polyarylpiperidine anion exchange membrane, which is obtained by self-polymerization of a branched monomer or copolymerization of a branched monomer with a biphenyl monomer and N-methyl-4-piperidone, followed by quaternization;

[0011] The structural formula of the branched monomer is as follows:

[0012] ;

[0013] Wherein, R1 and R2 are selected from hydrogen atoms and hydrocarbon groups containing 1 to 20 carbon atoms; n = 1 to 10;

[0014] The biphenyl monomer includes 、 、 or At least one of;

[0015] In the high molecular weight hyperbranched polyarylpiperidine anion exchange membrane, the number average molecular weight of the hyperbranched polyarylpiperidine polymer is greater than 100k.

[0016] As a further technical solution, the molar ratio of the branching monomer, biphenyl monomer and N-methyl-4-piperidone is (20~100): (0~100): (0~160).

[0017] In a second aspect, the present invention provides a method for preparing the above-mentioned high molecular weight hyperbranched polyarylpiperidine anion exchange membrane, comprising the following steps:

[0018] a branched monomer is dissolved in a solvent or a branched monomer, a biphenyl monomer and N-methyl-4-piperidone is dissolved in a solvent, and then trifluoroacetic acid and trifluoromethanesulfonic acid are added for a dehydration condensation reaction catalyzed by a super acid;

[0019] b. The polymer obtained by the dehydration condensation reaction in step a is collected and dissolved in a polar solvent to obtain a polymer solution, and then an alkaline substance is added and the reaction is carried out at 70~100°C for 12~48h, followed by the addition of iodomethane and the reaction is carried out at 20~25°C for 12~48h to complete the quaternization conversion and obtain a quaternized hyperbranched polyarylpiperidine polymer;

[0020] c. The quaternized hyperbranched polyaryl piperidine polymer obtained in step b is dissolved in a polar solvent to obtain a quaternized hyperbranched polyaryl piperidine polymer solution, and then the quaternized hyperbranched polyaryl piperidine polymer solution is sequentially cast, dried, soaked in an alkaline solution, washed and dried to prepare a high molecular weight hyperbranched polyaryl piperidine anion exchange membrane.

[0021] As a further technical solution, in step a, the solvent includes dichloromethane;

[0022] In step a, the ratio of the branched monomer, solvent, trifluoroacetic acid and trifluoromethanesulfonic acid is 20-100 mmol: 5-20 ml: 1-5 ml: 5-10 ml;

[0023] In step a, the temperature of the dehydration condensation reaction is -5~5°C, and the reaction time is 5~24h.

[0024] As a further technical solution, in step b, the polar solvent includes at least one of tetrahydrofuran, acetonitrile, N-methylpyrrolidone, N,N-dimethylformamide or dimethyl sulfoxide;

[0025] In step b, the concentration of the polymer solution is 3-30 wt%.

[0026] As a further technical solution, in step b, the alkaline substance includes at least one of KOH, NaOH, NH3·H2O or Ca(OH)2;

[0027] In step b, the mass ratio of the polymer, the alkaline substance and methyl iodide is 1: (0.5-5): (1-5).

[0028] As a further technical solution, in step c, the polar solvent includes N,N-dimethylformamide;

[0029] In step c, the concentration of the quaternized hyperbranched polyarylpiperidine polymer solution is 3-30 wt %.

[0030] As a further technical solution, in step c, the alkaline solution is a KOH aqueous solution with a concentration of 0.8-1.2 mol / L;

[0031] In step c, the soaking temperature of the alkaline solution is 55-65° C., and the soaking time is 12-48 hours.

[0032] As a further technical solution, the drying temperature is 50-80°C and the drying time is 8-24h;

[0033] In step c, the drying temperature is 45-55° C., and the drying time is 8-10 hours.

[0034] In a third aspect, the present invention provides the use of the high molecular weight hyperbranched polyarylpiperidine anion exchange membrane in the preparation of alkaline water electrolysis materials or alkaline fuel cell materials.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The high molecular weight hyperbranched polyarylpiperidine anion exchange membrane provided by the present invention is prepared by introducing a trifunctional ABB type aromatic piperidine monomer (containing both piperidone and benzene rings in one molecule) into a polyarylpiperidine polymer as a polymerization unit for generating branching points. The hyperbranched polyarylpiperidine anion exchange membrane has a free volume greater than that of a linear polymer, thereby exhibiting ultrahigh electrical conductivity; the high molecular weight polymer main chain ( M n Greater than 100K) gives it excellent alkali resistance and mechanical strength; at the same time, the anion exchange membrane has a low water absorption and swelling rate and dimensional stability, is suitable for water electrolysis to produce hydrogen and alkaline fuel cells, and has broad application prospects. DETAILED DESCRIPTION

[0037] Below in conjunction with embodiment and example, embodiment of the present invention is described in detail, but those skilled in the art will appreciate that the following embodiment and example are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiment in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise all fall within the scope of protection of the present invention. Unspecified conditions are carried out according to the conditions of normal conditions or manufacturer's recommendations. Reagents used or instruments not specified by the manufacturer are conventional products that can be purchased commercially.

[0038] In a first aspect, the present invention provides a high molecular weight hyperbranched polyarylpiperidine anion exchange membrane, which is obtained by self-polymerization of a branched monomer or copolymerization of a branched monomer with a biphenyl monomer and N-methyl-4-piperidone, and then quaternization of the tertiary amine nitrogen atom to form a quaternary ammonium salt;

[0039] The structural formula of the branched monomer is as follows:

[0040] ;

[0041] Wherein, R1 and R2 are selected from hydrogen atoms and hydrocarbon groups containing 1 to 20 carbon atoms; n = 1 to 10;

[0042] The biphenyl monomer includes 、 、 or At least one of;

[0043] In the high molecular weight hyperbranched polyarylpiperidine anion exchange membrane, the number average molecular weight of the hyperbranched polyarylpiperidine polymer is greater than 100k.

[0044] The high molecular weight hyperbranched polyaryl piperidine anion exchange membrane provided by the present invention is prepared by introducing a trifunctional ABB type aromatic piperidine monomer into a polyaryl piperidine polymer as a polymerization unit for generating branching points. The anion exchange membrane has a free volume greater than that of a linear polymer, thereby exhibiting ultrahigh electrical conductivity; the high molecular weight polymer main chain ( M n Greater than 100K) gives it excellent alkali resistance and mechanical strength; at the same time, the anion exchange membrane has a low water absorption and swelling rate and dimensional stability, is suitable for water electrolysis to produce hydrogen and alkaline fuel cells, and has broad application prospects.

[0045] In some optional embodiments, the high molecular weight hyperbranched polyarylpiperidine anion exchange membrane is formed by self-polymerization of a branched monomer or copolymerization of a branched monomer with a biphenyl monomer and N-methyl-4-piperidone, and the molar ratio of the branched monomer, biphenyl monomer and N-methyl-4-piperidone is (20~100):(0~100):(0~160).

[0046] In a second aspect, the present invention provides a method for preparing the above-mentioned high molecular weight hyperbranched polyarylpiperidine anion exchange membrane, comprising the following steps:

[0047] a branched monomer is dissolved in a solvent or a branched monomer, a biphenyl monomer and N-methyl-4-piperidone is dissolved in a solvent, and then trifluoroacetic acid and trifluoromethanesulfonic acid are added for a dehydration condensation reaction catalyzed by a super acid;

[0048] b. The polymer obtained by the dehydration condensation reaction in step a is collected and dissolved in a polar solvent to obtain a polymer solution, and then an alkaline substance is added and the reaction is carried out at 70~100°C for 12~48h, followed by the addition of iodomethane and the reaction is carried out at 20~25°C for 12~48h to complete the quaternization conversion and obtain a quaternized hyperbranched polyarylpiperidine polymer;

[0049] c. The quaternized hyperbranched polyaryl piperidine polymer obtained in step b is dissolved in a polar solvent to obtain a quaternized hyperbranched polyaryl piperidine polymer solution, and then the quaternized hyperbranched polyaryl piperidine polymer solution is sequentially cast, dried, soaked in an alkaline solution, washed and dried to prepare a high molecular weight hyperbranched polyaryl piperidine anion exchange membrane.

[0050] The preparation method is simple and convenient. The prepared high-molecular-weight hyperbranched polyarylpiperidine anion exchange membrane has good electrical conductivity, excellent alkali resistance and mechanical strength, low water absorption and swelling rate, and dimensional stability. It is suitable for hydrogen production from water electrolysis and alkaline fuel cells and has broad application prospects.

[0051] In some optional embodiments, in step a, the solvent includes dichloromethane;

[0052] In step a, the ratio of the branched monomer, solvent, trifluoroacetic acid and trifluoromethanesulfonic acid is 20-100 mmol: 5-20 ml: 1-5 ml: 5-10 ml;

[0053] In step a, the temperature of the dehydration condensation reaction can be, but is not limited to, -5°C, 0°C or 5°C, and the reaction time can be, but is not limited to, 5h, 10h or 24h.

[0054] In some optional embodiments, in step b, the polar solvent includes at least one of tetrahydrofuran, acetonitrile, N-methylpyrrolidone, N,N-dimethylformamide or dimethyl sulfoxide;

[0055] In step b, the concentration of the polymer solution may be, for example, but not limited to, 3 wt%, 15 wt% or 30 wt%.

[0056] In some optional embodiments, in step b, the alkaline substance includes but is not limited to KOH, NaOH, NH3·H2O or Ca(OH)2;

[0057] In step b, the mass ratio of the polymer, the alkaline substance and methyl iodide is 1: (0.5-5): (1-5).

[0058] In some optional embodiments, in step c, the polar solvent includes but is not limited to N,N-dimethylformamide;

[0059] In step c, the concentration of the quaternized hyperbranched polyarylpiperidine polymer solution can be, for example, but not limited to, 3 wt%, 15 wt% or 30 wt%.

[0060] In some optional embodiments, in step c, the alkaline solution is a KOH aqueous solution with a concentration of 0.8-1.2 mol / L;

[0061] In step c, to achieve a good quaternization effect, the soaking temperature of the alkaline solution can be, for example, but not limited to, 55° C., 60° C., or 65° C., and the soaking time can be, for example, but not limited to, 12 h, 24 h, or 48 h.

[0062] In some optional embodiments, the drying temperature may be, but not limited to, 50° C., 65° C., or 80° C., and the drying time may be, but not limited to, 8 h, 16 h, or 24 h.

[0063] In step c, the drying temperature may be, but is not limited to, 45° C., 50° C., or 55° C., and the drying time may be, but is not limited to, 8 h, 9 h, or 10 h.

[0064] In a third aspect, the present invention provides the use of the high molecular weight hyperbranched polyarylpiperidine anion exchange membrane in the preparation of alkaline water electrolysis materials or alkaline fuel cell materials.

[0065] The present invention is further described below by means of specific examples and comparative examples. However, it should be understood that these examples are merely provided for more detailed description and are not to be construed as limiting the present invention in any form.

[0066] Example 1

[0067] A method for preparing a high molecular weight hyperbranched polyarylpiperidine anion exchange membrane, the method comprising the following steps:

[0068] S1: 80 mmol of branched monomer, 20 mmol of biphenyl monomer, and 40 mmol of N-methyl-4-piperidone were added to a 50 mL round-bottom flask. The structures of the branched monomer and biphenyl monomer are shown below:

[0069] Branched monomers: ;

[0070] Biphenyl monomer: .

[0071] The round-bottom flask was fixed on a magnetic stirrer, and 10 mL of dichloromethane was added and stirred to dissolve the monomers. The round-bottom flask was then placed in a glass dish filled with ice water. The temperature of the solution in the round-bottom flask was monitored with a thermometer. 1 mL of trifluoroacetic acid and 5 mL of trifluoromethanesulfonic acid were added dropwise to the solution at 0°C. The mixture was then kept warm for 5 hours. The reaction solution was then added to a potassium hydroxide aqueous solution and precipitated and filtered to obtain a polymer solid.

[0072] S2: washing the polymer solid with pure water until its pH is neutral, and then drying it at 60° C. for 8 h; adding 1 g of the dried polymer solid and tetrahydrofuran to another round-bottom flask, stirring and dissolving them at 40° C. to obtain a polymer solution with a concentration of 3 wt %. When the polymer solution is cooled to room temperature, adding 0.5 g of potassium hydroxide to the polymer solution, and then stirring and keeping the mixture at 70° C. for 48 h. After the reaction solution is cooled to room temperature, adding 1 g of iodomethane, and stirring and reacting at room temperature for 12 h to obtain a hyperbranched polyarylpiperidine polymer solution;

[0073] S3: adding the hyperbranched polyarylpiperidine polymer solution in step S2 dropwise into pure water for precipitation, filtering and washing the solid with pure water until the pH thereof is neutral, and then drying the solid at 55° C. for 10 h to obtain a hyperbranched polyarylpiperidine polymer;

[0074] S4: Take 1 g of the branched polyarylpiperidine polyelectrolyte resin obtained in step S3 and dissolve it in N,N-dimethylformamide to obtain a polyelectrolyte resin solution with a concentration of 3 wt%, and cast the polyelectrolyte resin solution on a glass plate, dry it at 50 ° C for 24 hours to form a film, and then place the dried film in a potassium hydroxide aqueous solution with a concentration of 1 mol / L and soak it at 60 ° C for 12 hours. After taking it out, wash the residual potassium hydroxide with pure water, and then place the film in a vacuum drying oven for drying at a drying temperature of 45 ° C, a vacuum degree of -0.1 MPa, and a drying time of 10 hours. After drying, a hyperbranched polyarylpiperidine anion exchange membrane is obtained.

[0075] Example 2

[0076] A method for preparing a high molecular weight hyperbranched polyarylpiperidine anion exchange membrane, the method comprising the following steps:

[0077] S1: Add 100 mmol of branched monomer to a 50 mL round-bottom flask. The structure of the branched monomer is shown below:

[0078] Branched monomers: .

[0079] The round-bottom flask was fixed on a magnetic stirrer, and 5 mL of dichloromethane was added and stirred to dissolve the monomers. The round-bottom flask was then placed in a glass dish filled with ice water. The temperature of the solution in the round-bottom flask was monitored with a thermometer. 2 mL of trifluoroacetic acid and 10 mL of trifluoromethanesulfonic acid were added dropwise to the solution at 0°C. The mixture was then kept warm for 10 hours. The reaction solution was then added to an aqueous sodium hydroxide solution, precipitated, and filtered to obtain a polymer solid.

[0080] S2: washing the polymer solid with pure water until its pH is neutral, and then drying it at 60° C. for 8 h; adding 1 g of the dried polymer solid and acetonitrile to another round-bottom flask, stirring and dissolving them at 40° C. to obtain a polymer solution with a concentration of 15 wt %. When the polymer solution is cooled to room temperature, adding 1 g of sodium hydroxide to the polymer solution, and then stirring and keeping the mixture at 80° C. for 36 h. After the reaction solution is cooled to room temperature, adding 2 g of iodomethane, and stirring and reacting at room temperature for 24 h to obtain a hyperbranched polyarylpiperidine polymer solution;

[0081] S3: adding the hyperbranched polyarylpiperidine polymer solution in step S2 dropwise into pure water for precipitation, filtering and washing the solid with pure water until the pH thereof is neutral, and then drying the solid at 55° C. for 10 h to obtain a hyperbranched polyarylpiperidine polymer;

[0082] S4: Take 1 g of the branched polyarylpiperidine polyelectrolyte resin obtained in step S3 and dissolve it in N,N-dimethylformamide to obtain a polyelectrolyte resin solution with a concentration of 15 wt%, and cast the polyelectrolyte resin solution on a glass plate, dry it at 65 ° C for 16 hours to form a film, and then place the dried film in a potassium hydroxide aqueous solution with a concentration of 1 mol / L and soak it at 60 ° C for 12 hours. After taking it out, wash the residual potassium hydroxide with pure water, and then place the film in a vacuum drying oven for drying at a drying temperature of 50 ° C, a vacuum degree of -0.1 MPa, and a drying time of 9 hours. After drying, a hyperbranched polyarylpiperidine anion exchange membrane is obtained.

[0083] Example 3

[0084] A method for preparing a high molecular weight hyperbranched polyarylpiperidine anion exchange membrane, the method comprising the following steps:

[0085] S1: Add 60 mmol of branched monomer, 40 mmol of biphenyl monomer, and 60 mmol of N-methyl-4-piperidone to a 50 mL round-bottom flask. The structures of the branched monomer and biphenyl monomer are shown below:

[0086] Branched monomers: ;

[0087] Biphenyl monomer: .

[0088] The round-bottom flask was fixed on a magnetic stirrer, and 15 mL of dichloromethane was added and stirred to dissolve the monomers. The round-bottom flask was then placed in a glass dish filled with ice water. The temperature of the solution in the round-bottom flask was monitored with a thermometer. 3 mL of trifluoroacetic acid and 5 mL of trifluoromethanesulfonic acid were added dropwise to the solution at 0°C. The mixture was then kept warm for 15 hours. The reaction solution was then added to a calcium hydroxide aqueous solution for precipitation and filtration to obtain a polymer solid.

[0089] S2: washing the polymer solid with pure water until its pH is neutral, and then drying it at 60° C. for 8 h; adding 1 g of the dried polymer solid and N-methylpyrrolidone to another round-bottom flask, stirring and dissolving them at 40° C. to obtain a polymer solution with a concentration of 30 wt %. When the polymer solution is cooled to room temperature, adding 2 g of calcium hydroxide to the polymer solution, and then stirring and keeping the mixture at 90° C. for 24 h. After the reaction solution is cooled to room temperature, adding 5 g of iodomethane, and stirring and reacting at room temperature for 36 h to obtain a hyperbranched polyarylpiperidine polymer solution;

[0090] S3: adding the hyperbranched polyarylpiperidine polymer solution in step S2 dropwise into pure water for precipitation, filtering and washing the solid with pure water until the pH thereof is neutral, and then drying the solid at 55° C. for 10 h to obtain a hyperbranched polyarylpiperidine polymer;

[0091] S4: Take 1 g of the branched polyarylpiperidine polyelectrolyte resin obtained in step S3 and dissolve it in N,N-dimethylformamide to obtain a polyelectrolyte resin solution with a concentration of 30 wt%, and cast the polyelectrolyte resin solution on a glass plate, dry it at 80 ° C for 8 hours to form a film, and then place the dried film in a potassium hydroxide aqueous solution with a concentration of 1 mol / L and soak it at 60 ° C for 12 hours. After taking it out, wash the residual potassium hydroxide with pure water, and then place the film in a vacuum drying oven for drying at a drying temperature of 55 ° C, a vacuum degree of -0.1 MPa, and a drying time of 8 hours. After drying, a branched polyarylpiperidine anion exchange membrane is obtained.

[0092] Example 4

[0093] A method for preparing a high molecular weight hyperbranched polyarylpiperidine anion exchange membrane, the method comprising the following steps:

[0094] S1: 40 mmol of branched monomer, 60 mmol of biphenyl monomer, and 90 mmol of N-methyl-4-piperidone were added to a 50 mL round-bottom flask. The structures of the branched monomer and biphenyl monomer are shown below:

[0095] Branched monomers: ;

[0096] Biphenyl monomer: .

[0097] The round-bottom flask was fixed on a magnetic stirrer, and 20 mL of dichloromethane was added and stirred to dissolve the monomers. The round-bottom flask was then placed in a glass dish filled with ice water. The temperature of the solution in the round-bottom flask was monitored with a thermometer. 4 mL of trifluoroacetic acid and 10 mL of trifluoromethanesulfonic acid were added dropwise to the solution at 0°C. The mixture was then kept warm for 20 hours. The reaction solution was then added to aqueous ammonia for precipitation and filtration to obtain a polymer solid.

[0098] S2: washing the polymer solid with pure water until its pH is neutral, and then drying it at 60° C. for 8 h; adding 1 g of the dried polymer solid and N,N-dimethylformamide to another round-bottom flask, stirring and dissolving them at 40° C. to obtain a polymer solution with a concentration of 3 wt%. When the polymer solution is cooled to room temperature, adding 5 g of ammonia water to the polymer solution, and then stirring and keeping the mixture at 100° C. for 12 h. After the reaction solution is cooled to room temperature, adding 5 g of iodomethane, and stirring and reacting at room temperature for 48 h to obtain a hyperbranched polyarylpiperidine polymer solution;

[0099] S3: adding the hyperbranched polyarylpiperidine polymer solution in step S2 dropwise into pure water to precipitate, filtering and washing the solid with pure water until the pH is neutral, and then drying the solid at 60° C. for 9 h to obtain a hyperbranched polyarylpiperidine polymer;

[0100] S4: Take 1 g of the branched polyarylpiperidine polyelectrolyte resin obtained in step S3 and dissolve it in N,N-dimethylformamide to obtain a polyelectrolyte resin solution with a concentration of 3 wt%, and cast the polyelectrolyte resin solution on a glass plate, dry it at 50 ° C for 24 hours to form a film, and then place the dried film in a potassium hydroxide aqueous solution with a concentration of 1 mol / L and soak it at 60 ° C for 12 hours. After taking it out, wash the residual potassium hydroxide with pure water, and then place the film in a vacuum drying oven for drying at a drying temperature of 50 ° C, a vacuum degree of -0.1 MPa, and a drying time of 9 hours. After drying, a hyperbranched polyarylpiperidine anion exchange membrane is obtained.

[0101] Example 5

[0102] A method for preparing a high molecular weight hyperbranched polyarylpiperidine anion exchange membrane, the method comprising the following steps:

[0103] S1: Add 20 mmol of branched monomer, 80 mmol of biphenyl monomer, and 160 mmol of N-methyl-4-piperidone to a 50 mL round-bottom flask. The structures of the branched monomer and biphenyl monomer are shown below:

[0104] Branched monomers: ;

[0105] Biphenyl monomer: .

[0106] The round-bottom flask was fixed on a magnetic stirrer, and 15 mL of dichloromethane was added and stirred to dissolve the monomers. The round-bottom flask was then placed in a glass dish filled with ice water. The temperature of the solution in the round-bottom flask was monitored with a thermometer. 5 mL of trifluoroacetic acid and 10 mL of trifluoromethanesulfonic acid were added dropwise to the solution at 0°C. The mixture was then kept warm for 24 hours. The reaction solution was then added to an aqueous sodium hydroxide solution and precipitated and filtered to obtain a polymer solid.

[0107] S2: washing the polymer solid with pure water until its pH is neutral, and then drying it at 60° C. for 8 h; adding 1 g of the dried polymer solid and dimethyl sulfoxide to another round-bottom flask, stirring and dissolving them at 40° C. to obtain a polymer solution with a concentration of 3 wt%. When the polymer solution is cooled to room temperature, adding 5 g of sodium hydroxide aqueous solution to the polymer solution, and then stirring and keeping the mixture at 90° C. for 24 h. After the reaction solution is cooled to room temperature, adding 2 g of iodomethane, and stirring and reacting at room temperature for 36 h to obtain a hyperbranched polyarylpiperidine polymer solution;

[0108] S3: adding the hyperbranched polyarylpiperidine polymer solution in step S2 dropwise into pure water for precipitation, filtering and washing the solid with pure water until the pH thereof is neutral, and then drying the solid at 55° C. for 10 h to obtain a hyperbranched polyarylpiperidine polymer;

[0109] S4: Take 1 g of the branched polyarylpiperidine polyelectrolyte resin obtained in step S3 and dissolve it in N,N-dimethylformamide to obtain a polyelectrolyte resin solution with a concentration of 3 wt%, and cast the polyelectrolyte resin solution on a glass plate, dry it at 50 ° C for 24 hours to form a film, and then place the dried film in a potassium hydroxide aqueous solution with a concentration of 1 mol / L and soak it at 60 ° C for 12 hours. After taking it out, wash the residual potassium hydroxide with pure water, and then place the film in a vacuum drying oven for drying at a drying temperature of 50 ° C, a vacuum degree of -0.1 MPa, and a drying time of 9 hours. After drying, a hyperbranched polyarylpiperidine anion exchange membrane is obtained.

[0110] Example 6

[0111] A method for preparing a high molecular weight hyperbranched polyarylpiperidine anion exchange membrane, the method comprising the following steps:

[0112] S1: Add 50 mmol of branched monomer, 100 mmol of biphenyl monomer, and 100 mmol of N-methyl-4-piperidone to a 50 mL round-bottom flask. The structures of the branched monomer and biphenyl monomer are shown below:

[0113] Branched monomers: ;

[0114] Biphenyl monomer: .

[0115] The round-bottom flask was fixed on a magnetic stirrer, and 15 mL of dichloromethane was added and stirred to dissolve the reaction precursor. The round-bottom flask was then placed in a basin of ice water. The temperature of the solution in the round-bottom flask was monitored with a thermometer. 3 mL of trifluoroacetic acid and 5 mL of trifluoromethanesulfonic acid were added dropwise to the solution at 0°C. The mixture was then kept warm for 15 hours. The reaction solution was then added to an aqueous sodium hydroxide solution, precipitated, and filtered to obtain a polymer solid.

[0116] S2: washing the polymer solid with pure water until its pH is neutral, and then drying it at 60°C for 8 hours; adding 1 g of the dried polymer solid and tetrahydrofuran to another round-bottom flask, stirring and dissolving at 40°C to obtain a polymer solution with a concentration of 3 wt%, and when the polymer solution is cooled to room temperature, adding 2 g of sodium hydroxide to the polymer solution, and then stirring and keeping the mixture at 90°C for 24 hours. After the reaction solution is cooled to room temperature, adding 5 g of iodomethane, and stirring and reacting at room temperature for 36 hours to obtain a linear polyaryl piperidine polymer solution;

[0117] S3: adding the linear polyarylpiperidine polymer solution in step S2 dropwise into pure water to precipitate, filtering and washing the solid with pure water until the pH is neutral, and then drying the solid at 55° C. for 10 h to obtain a linear polyarylpiperidine polymer;

[0118] S4: Take 1 g of the linear polyarylpiperidine polyelectrolyte resin obtained in step S3 and dissolve it in N,N-dimethylformamide to obtain a polyelectrolyte resin solution with a concentration of 3 wt%, and cast the polyelectrolyte resin solution on a glass plate, dry it at 50 ° C for 24 hours to form a film, and then place the dried film in a potassium hydroxide aqueous solution with a concentration of 1 mol / L and soak it at 60 ° C for 12 hours. After taking it out, wash the residual potassium hydroxide with pure water, and then place the film in a vacuum drying oven for drying at a drying temperature of 50 ° C, a vacuum degree of -0.1 MPa, and a drying time of 9 hours. After drying, a hyperbranched polyarylpiperidine anion exchange membrane is obtained.

[0119] Comparative Example 1

[0120] A method for preparing a linear polyarylpiperidine anion exchange membrane, the method comprising the following steps:

[0121] S1: Add 100 mmol of biphenyl monomer and 150 mmol of N-methyl-4-piperidone to a 50 mL round-bottom flask. The structure of the biphenyl monomer is shown below:

[0122] Biphenyl monomer: .

[0123] The round-bottom flask was fixed on a magnetic stirrer, and 15 mL of dichloromethane was added and stirred to dissolve the reaction precursor. The round-bottom flask was then placed in a basin of ice water. The temperature of the solution in the round-bottom flask was monitored with a thermometer. 3 mL of trifluoroacetic acid and 5 mL of trifluoromethanesulfonic acid were added dropwise to the solution at 0°C. The mixture was then kept warm for 15 hours. The reaction solution was then added to an aqueous sodium hydroxide solution, precipitated, and filtered to obtain a polymer solid.

[0124] S2: washing the polymer solid with pure water until its pH is neutral, and then drying it at 60°C for 8 hours; adding 1 g of the dried polymer solid and tetrahydrofuran to another round-bottom flask, stirring and dissolving at 40°C to obtain a polymer solution with a concentration of 3 wt%, and when the polymer solution is cooled to room temperature, adding 2 g of sodium hydroxide to the polymer solution, and then stirring and keeping the mixture at 90°C for 24 hours. After the reaction solution is cooled to room temperature, adding 5 g of iodomethane, and stirring and reacting at room temperature for 36 hours to obtain a linear polyaryl piperidine polymer solution;

[0125] S3: adding the linear polyarylpiperidine polymer solution in step S2 dropwise into pure water to precipitate, filtering and washing the solid with pure water until the pH is neutral, and then drying the solid at 55° C. for 10 h to obtain a linear polyarylpiperidine polymer;

[0126] S4: Take 1 g of the linear polyarylpiperidine polyelectrolyte resin obtained in step S3 and dissolve it in N,N-dimethylformamide to obtain a polyelectrolyte resin solution with a concentration of 3 wt%, and cast the polyelectrolyte resin solution on a glass plate, dry it at 50 ° C for 24 hours to form a film, and then place the dried film in a potassium hydroxide aqueous solution with a concentration of 1 mol / L and soak it at 60 ° C for 12 hours. After taking it out, wash the residual potassium hydroxide with pure water, and then place the film in a vacuum drying oven for drying at a drying temperature of 50 ° C, a vacuum degree of -0.1 MPa, and a drying time of 9 hours. After drying, a linear polyarylpiperidine anion exchange membrane is obtained.

[0127] Performance Testing

[0128] 1. Molecular weight test

[0129] The hyperbranched polyarylpiperidine polymer obtained in Examples 1 to 6 was dissolved in m-trichlorobenzene and subjected to gel permeation chromatography at 140° C. to obtain the number average molecular weight. M n and molecular weight distribution PDI, the results are recorded in Table 1. The results in the table show that the number average molecular weight of the hyperbranched polyarylpiperidine obtained by this method is greater than 100k, which can ensure that the membrane material has high strength and high alkali resistance stability.

[0130] 2. Conductivity test

[0131] The electrochemical impedance spectroscopy (EIS) method was used to test the ionic conductivity of the membrane. Before the test, the anion exchange membranes prepared in Examples 1 to 6 and Comparative Example 1 were cut into 1 cm × 3 cm membrane samples with scissors and immersed in a 1 M NaOH solution for 2 days to allow sufficient exchange of anions in the membrane. After the ion exchange was completed, the membrane was taken out and the excess alkali solution on the membrane surface was washed three times with deionized water. The thickness of the membrane sample was measured with a thickness gauge and recorded as t. Then, the electrochemical impedance spectroscopy was tested by a Zahner IM6EX electrochemical workstation at 30°C, 40°C, 50°C, 60°C, 70°C, and 80°C to record the ohmic resistance (R) of the membrane at the corresponding temperature. The ionic conductivity (σ) of the membrane sample at different temperatures can be calculated by the following formula:

[0132]

[0133] Wherein, σ refers to the ionic conductivity, d represents the size of the electrode spacing, and the unit is cm; w and t represent the width and thickness of the measured membrane sample, respectively, and the unit is cm.

[0134] The conductivity test results are summarized in Table 1. It can be seen from the table that the conductivity of each high molecular weight hyperbranched polyarylpiperidine anion exchange membrane in the examples is significantly greater than that of the comparative example.

[0135] 3. Water absorption and swelling test

[0136] The anion exchange membranes prepared in Examples 1 to 6 and Comparative Example 1 were subjected to water absorption and swelling tests. First, the membrane was cut into 1 cm × 1 cm samples to be tested with scissors. The membrane was then soaked in 1 M NaOH solution for 2 days to allow sufficient exchange of anions in the membrane. After the ion exchange was completed, the membrane was soaked in deionized water at 30°C, 40°C, 50°C, 60°C, 70°C, and 80°C for 12 h. After the soaking was completed, the membrane was taken out and the moisture on the surface of the membrane sample was carefully absorbed with qualitative filter paper. The mass and size of the membrane sample at the corresponding temperature were measured and recorded as m, m, and m, respectively. 湿 With L 湿 Repeat the above operation three times to ensure the accuracy of the test. After the above operation is completed, the film sample is placed in an oven at 80°C and dried to a constant weight and the mass and size of the film sample at this time are measured and recorded as m 干 With L 干 The WU and SR of the membrane sample can be calculated using the following formulas:

[0137]

[0138]

[0139] The water absorption and swelling results are summarized in Table 1. It can be seen from the table that the water absorption and swelling ratio of each high molecular weight hyperbranched polyarylpiperidine anion exchange membrane in the examples are significantly smaller than those in the comparative examples.

[0140] 4. Mechanical properties test

[0141] The mechanical properties of the anion exchange membranes prepared in Examples 1–6 were characterized using an MTS E43 electronic universal testing machine. Before testing, membrane samples were cut into dumbbell shapes measuring 4 × 50 mm using a sheet cutter. The membranes were then clamped to the testing machine fixture at room temperature, and the gauge length was adjusted to 10 mm before testing began. The tensile rate was set at 5 mm / min.

[0142] The mechanical properties test results are summarized in Table 1. It can be seen from the table that the mechanical strength and elongation at break of the high molecular weight hyperbranched polyarylpiperidine anion exchange membranes in the examples are significantly higher than those in the comparative examples.

[0143] 5. Alkali resistance stability test

[0144] The anion exchange membranes prepared in Examples 1-6 were immersed in a 1 mol / L KOH solution at 80°C. The conductivity of the anion exchange membranes was measured at different times, and the time until the performance decayed by 10% was recorded as an evaluation index of alkali resistance stability. The results are summarized in Table 1. As can be seen from the table, the alkali resistance stability of the high molecular weight hyperbranched polyarylpiperidine anion exchange membranes in the examples was significantly better than that of the comparative examples.

[0145] Table 1. Summary of performance comparison of membranes in various examples and comparative examples

[0146] .

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high molecular weight hyperbranched polyarylpiperidine anion exchange membrane, characterized in that It is obtained by self-polymerization of branched monomers or copolymerization of branched monomers with biphenyl monomers and N-methyl-4-piperidone, followed by quaternization conversion; The structural formula of the branched monomer is as follows: ； Wherein, R1 and R2 are selected from hydrogen atoms and hydrocarbon groups containing 1 to 20 carbon atoms; n = 1 to 10; The biphenyl monomer includes 、 、 or At least one of; In the high molecular weight hyperbranched polyarylpiperidine anion exchange membrane, the number average molecular weight of the hyperbranched polyarylpiperidine polymer is greater than 100k.

2. The high molecular weight hyperbranched polyarylpiperidine anion exchange membrane according to claim 1, characterized in that The molar ratio of the branching monomer, the biphenyl monomer and N-methyl-4-piperidone is (20-100): (0-100): (0-160).

3. The method for preparing a high molecular weight hyperbranched polyarylpiperidine anion exchange membrane according to claim 1 or 2, wherein: The steps include: a branched monomer is dissolved in a solvent or a branched monomer, a biphenyl monomer and N-methyl-4-piperidone is dissolved in a solvent, and then trifluoroacetic acid and trifluoromethanesulfonic acid are added for a dehydration condensation reaction catalyzed by a super acid; b. The polymer obtained by the dehydration condensation reaction in step a is collected and dissolved in a polar solvent to obtain a polymer solution, and then an alkaline substance is added and the reaction is carried out at 70~100°C for 12~48h, followed by the addition of iodomethane and the reaction is carried out at 20~25°C for 12~48h to complete the quaternization conversion and obtain a quaternized hyperbranched polyarylpiperidine polymer; c. The quaternized hyperbranched polyaryl piperidine polymer obtained in step b is dissolved in a polar solvent to obtain a quaternized hyperbranched polyaryl piperidine polymer solution, and then the quaternized hyperbranched polyaryl piperidine polymer solution is sequentially cast, dried, soaked in an alkaline solution, washed and dried to prepare a high molecular weight hyperbranched polyaryl piperidine anion exchange membrane.

4. The preparation method according to claim 3, characterized in that In step a, the solvent includes dichloromethane; In step a, the ratio of the branched monomer, solvent, trifluoroacetic acid and trifluoromethanesulfonic acid is 20-100 mmol: 5-20 ml: 1-5 ml: 5-10 ml; In step a, the temperature of the dehydration condensation reaction is -5~5°C, and the reaction time is 5~24h.

5. The preparation method according to claim 3, characterized in that In step b, the polar solvent includes at least one of tetrahydrofuran, acetonitrile, N-methylpyrrolidone, N,N-dimethylformamide or dimethyl sulfoxide; In step b, the concentration of the polymer solution is 3-30 wt%.

6. The preparation method according to claim 3, characterized in that In step b, the alkaline substance includes at least one of KOH, NaOH, NH3·H2O or Ca(OH)2; In step b, the mass ratio of the polymer, the alkaline substance and methyl iodide is 1: (0.5-5): (1-5).

7. The preparation method according to claim 3, characterized in that In step c, the polar solvent includes N,N-dimethylformamide; In step c, the concentration of the quaternized hyperbranched polyarylpiperidine polymer solution is 3-30 wt %.

8. The preparation method according to claim 3, characterized in that In step c, the alkaline solution is a KOH aqueous solution with a concentration of 0.8-1.2 mol / L; In step c, the soaking temperature of the alkaline solution is 55-65° C., and the soaking time is 12-48 hours.

9. The preparation method according to claim 3, characterized in that The drying temperature is 50-80°C and the drying time is 8-24 hours; In step c, the drying temperature is 45-55° C., and the drying time is 8-10 hours.

10. Use of the high molecular weight hyperbranched polyarylpiperidine anion exchange membrane according to claim 1 or 2 in the preparation of alkaline water electrolysis materials or alkaline fuel cell materials.

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