Double-side-chain anion exchange membrane as well as preparation method and application thereof

Abstract

The invention relates to the technical field of membrane separation, and discloses a double-side-chain anion exchange membrane as well as a preparation method and application thereof. The anion exchange membrane comprises a plurality of polyphenyl ether molecular chains, the polyphenyl ether molecular chain has a structure as shown in a formula I; # imgabs0 # Q1, Q2, Q3 and Q4 are each independently a group represented by formula II, a group represented by formula III, Br or H; at least two of Q1, Q2, Q3 and Q4 are a group as shown in a formula II and a group as shown in a formula III; at least two polyphenyl ether molecular chains of # imgabs 1 # are connected through a structure Ar from a cross-linking agent; according to the double-side-chain anion exchange membrane, two long-chain hydrophobic alkyl side chains are introduced into a polyphenyl ether molecular chain, so that the content of an active ion exchange matrix in the anion exchange membrane is remarkably increased, and the performance of the anion exchange membrane is improved.

Description

Technical Field

[0001] The invention relates to the technical field of membrane separation, and in particular to a double-side chain anion exchange membrane and a preparation method and application thereof. Background Art

[0002] As one of the seven nutrients, water is a necessity for human survival and the material basis for human production and life. A reliable and stable supply of fresh water is a necessary condition for the sustainable development of human society. Electrodialysis is one of the mainstream technologies for seawater desalination. Compared with other seawater desalination technologies, it has the following advantages: simple equipment, easy operation, no need to add additional chemicals, high efficiency, no pollution, etc.

[0003] Generally, an anion exchange membrane for electrodialysis with excellent performance needs to have suitable ion exchange capacity, water absorption rate and water content, etc. The larger the ion exchange capacity, the more active groups there are in the membrane, which is more conducive to ion migration during electrodialysis. CN109880138A discloses a method for preparing a polyisatin aromatic anion exchange membrane by grafting a long-chain ammonium salt onto polyisatin aromatics. The ion exchange capacity of the membrane is 1.2mmol / g, the water absorption rate is 11%, and the swelling degree is 13%; CN114824396A discloses a method for preparing a fluorenyl anion exchange membrane containing a comb-shaped side chain by grafting a quaternary ammonium ion group containing a flexible long carbon chain onto a fluorenyl unit. The theoretical value of the ion exchange capacity of the membrane is 1.369mmol / g, the test value is 1.08mmol / g, and the water content of the membrane at 30°C and 80°C is 21.64% and 38.47%, respectively. At present, most of the anion exchange membranes are polymers with single cationic groups grafted onto the side chains, resulting in a small number of ion exchange groups in the anion exchange membrane, making it difficult to form a continuous and effective ion channel, and the ion exchange efficiency is low. CN112851932A discloses an anion exchange membrane with three quaternary ammonium salts in series with multiple cationic side chains, which improves the polarity of the side chains and the functional group concentration in the ion channel. The anion exchange capacity of the anion exchange membrane is 1.92mmol / g, and the water absorption rate is 32.03% at room temperature, but the synthesis of the multiple cationic quaternary ammonium reagent is complex, and it faces great challenges in practical industrial applications. In addition, there are many problems in the research of anion exchange membranes, including high cost, complex preparation process, unsatisfactory physical and chemical properties, etc. Therefore, preparing an ion exchange membrane with a simple preparation method and high ion exchange capacity helps to promote the industrial development of electrodialysis seawater desalination technology. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of low ion exchange capacity and complicated preparation process of anion exchange membranes in the prior art, and to provide a double side chain anion exchange membrane and a preparation method and application thereof. In the double side chain anion exchange membrane, two long-chain hydrophobic alkyl side chains are introduced into the polyphenylene ether molecular chain, which significantly increases the content of active ion exchange matrix in the anion exchange membrane and improves the performance of the anion exchange membrane.

[0005] In order to achieve the above object, the first aspect of the present invention provides a double side chain anion exchange membrane, wherein the anion exchange membrane comprises a plurality of polyphenylene ether molecular chains; the polyphenylene ether molecular chains have a structure as shown in Formula I;

[0006]

[0007] Q1, Q2, Q3 and Q4 are each independently a group represented by formula II, a group represented by formula III, Br or H; and at least two of Q1, Q2, Q3 and Q4 are a group represented by formula II and a group represented by formula III;

[0008]

[0009] At least two polyphenylene ether molecular chains are connected by a structure Ar from a cross-linking agent;

[0010] Among them, R 1 , R 2 , R 4 , R 5 , R 7 , R 8 Each independently is H, CH 3 or CH 2 CH 3 , R 3 C 8 -C 25 A straight chain or branched alkyl group; R 6 C 2 -C 5 A straight chain alkylene group or a branched chain alkylene group; x is 0.3-0.8.

[0011] A second aspect of the present invention provides a method for preparing a double side chain anion exchange membrane, wherein the preparation method comprises:

[0012] (1) mixing compound A represented by formula 1, compound B represented by formula 2, brominated polyphenylene ether represented by formula 3, and an organic solvent, and reacting the mixture to obtain a solution containing a prepolymer;

[0013] (2) mixing a cross-linking agent with the product of step (1) to obtain a casting solution;

[0014] (3) coating the casting solution on a substrate and curing the substrate to obtain the double side chain anion exchange membrane;

[0015]

[0016] R 1 '、R 2 '、R 4 '、R 5 '、R 7 '、R 8 ' are independently H, CH 3 or CH 2 CH 3 , R 3 ' is C 8 -C 25 A straight chain or branched alkyl group; R 6 ' is C 2 -C 5 A straight chain alkylene or branched chain alkylene, X 1 and X 2 are each independently H or Br, and X 1 and X 2 At least one of them is Br; and x is 0.3-0.8.

[0017] The third aspect of the present invention provides a double side chain anion exchange membrane prepared by the above preparation method.

[0018] A fourth aspect of the present invention provides an application of the above-mentioned double side chain anion exchange membrane in a separation process.

[0019] Through the above technical solution, the double side chain anion exchange membrane provided by the present invention and its preparation method and application can achieve the following beneficial effects:

[0020] The double-side-chain anion exchange membrane provided in the present invention uses polyphenylene ether as a skeleton, and introduces two long-chain hydrophobic alkyl side chain groups on the molecular chain of the polyphenylene ether skeleton. Compared with traditional short side chains, the long-chain hydrophobic alkyl side chain groups have stronger activity and can promote the formation of a hydrophilic-hydrophobic microphase-separated aggregation structure in the membrane. At the same time, the introduction of the two long-chain hydrophobic alkyl side chain groups significantly increases the number of active ion exchange groups of the ion exchange membrane. The two cooperate synergistically to significantly improve the performance of the anion exchange membrane.

[0021] Furthermore, the long-chain hydrophobic alkyl side chain groups of the double-side chain anion exchange membrane provided by the present invention contain a plurality of quaternary ammonium salt groups, which can make the surface of the anion exchange membrane charged and maintain a high charge density.

[0022] The double-side chain anion exchange membrane provided by the present invention exhibits excellent performance. Specifically, the anion exchange membrane has the advantages of excellent ion exchange capacity, water absorption rate, swelling rate, etc. In some embodiments of the present invention, the anion exchange membrane has an ion exchange capacity of 1.32-1.99 mmol / g at 25°C, a water absorption rate of 12.5%-56.9%, and a swelling rate of 22.3-42.3%. It has broad application prospects in the fields of electrodialysis and seawater desalination. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the molecular structure of the double side chain ion exchange membrane of the present invention.

[0024] Figure 2 The Fourier transform infrared spectra (FTIR) of the ion exchange membranes of Example 3, Comparative Example 1 and Comparative Example 2 are shown.

[0025] Figure 3 Surface SEM images and cross-sectional SEM images of the ion exchange membranes of Examples 1-3 and Comparative Example 1 are shown. DETAILED DESCRIPTION

[0026] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0027] The first aspect of the present invention provides a double side chain anion exchange membrane, characterized in that the anion exchange membrane comprises a plurality of polyphenylene ether molecular chains; the polyphenylene ether molecular chains have a structure shown in Formula I;

[0028]

[0029] Q1, Q2, Q3 and Q4 are each independently a group represented by formula II, a group represented by formula III, Br or H; and at least two of Q1, Q2, Q3 and Q4 are a group represented by formula II and a group represented by formula III;

[0030]

[0031] At least two polyphenylene ether molecular chains are connected by a structure Ar from a cross-linking agent;

[0032] Among them, R 1 , R 2 , R 4 , R 5 , R 7, R 8 Each independently is H, CH 3 or CH 2 CH 3 , R 3 C 8 -C 25 A straight chain or branched alkyl group; R 6 C 2 -C 5 A straight chain alkylene group or a branched chain alkylene group; x is 0.3-0.8.

[0033] In the present invention, the double side chain anion exchange membrane uses polyphenylene ether as a skeleton, and introduces two long-chain hydrophobic alkyl side chain groups on the molecular chain of the polyphenylene ether skeleton. Compared with traditional short side chains, the long-chain hydrophobic alkyl side chains have stronger activity and can promote the formation of a hydrophilic and hydrophobic microphase-separated aggregation structure in the membrane. At the same time, the introduction of the two long-chain hydrophobic alkyl side chains significantly increases the number of active ion exchange groups of the ion exchange membrane. The two work together to significantly improve the performance of the anion exchange membrane.

[0034] Furthermore, the long-chain hydrophobic alkyl side chains of the double-side-chain anion exchange membrane provided by the present invention contain a plurality of quaternary ammonium salt groups, which can make the surface of the anion exchange membrane charged and maintain a high charge density.

[0035] In the present invention, when the side chain of the anion exchange membrane has the above-mentioned specific structure, and at least two polyphenylene ether molecular chains are connected through Ar with the above-mentioned specific structure, the structure has good chain flexibility and can form a good ion migration channel.

[0036] Furthermore, R 1 , R 2 , R 4 , R 5 , R 7 , R 8 Each independently is CH 2 CH 3 or CH 3 ; R 3 C 10 -C 20 A straight chain or branched alkyl group; R 6 C 2 -C 3 A straight chain alkylene group or a branched chain alkylene group; x is 0.4-0.6.

[0037] In a specific embodiment of the present invention, R 1 , R 2 CH 3 , R 3 C 18 of a straight chain alkyl group.

[0038] In a specific embodiment of the present invention, R 1 , R 2 CH 3 , R 3 C 10 of a straight chain alkyl group.

[0039] In a specific embodiment of the present invention, R 4 , R 5 , R 7 , R 8 Each independently is CH 3 , R 6 For ethylene.

[0040] In a specific embodiment of the present invention, R 4 , R 5 , R 7 , R 8 Each independently is CH 3 , R 6 For methylene.

[0041] According to the present invention, the Ar structure Ar structure from the cross-linking agent is selected from at least one of the following:

[0042]

[0043] Among them, R 9 and R 10 Each independently is H, OH or CH 3 ; R 11 and R 12 Each independently is H, CH 3 or CH 2 CH 3 ; n and m are each independently an integer of 1-3; p and q are each independently an integer of 1-3;

[0044] In the present invention, at least two polyphenylene ether molecular chains are connected by the above-mentioned specific Ar structure to form a stable network structure, which provides active sites for ion migration without reducing the ion exchange capacity of the membrane.

[0045] Furthermore, R 9 , R 10 , R 11 and R 12 Each is H, and n, m, p and q are all 1.

[0046] According to the present invention, based on the total molar amount of the anion exchange membrane, the molar content of the group represented by Formula II is 10-40%, the molar content of the group represented by Formula III is 20-60%, the molar content of Br is 0-5%, and the molar content of the Ar structure is 5-15%.

[0047] In the present invention, when the content of each structural unit in the anion exchange membrane satisfies the above range, the Ar structure and the main chain graft can form a cationic group imidazolyl, providing active sites for ion migration, thereby improving the performance of the anion exchange membrane.

[0048] In the present invention, in the process of preparing the anion exchange membrane, compounds A and B have basically no residue, indicating that in the present invention, when preparing the anion exchange membrane, compounds A and B can all react with brominated polyphenylene ether. Therefore, the content of each structural unit in the anion exchange membrane can be determined by the feeding amount.

[0049] Furthermore, based on the total molar amount of the anion exchange membrane, the molar content of the group represented by Formula II is 10-30%, the molar content of the group represented by Formula III is 30-50%, the molar content of Br is 0.2-2%, and the molar content of the Ar structure is 6-9%.

[0050] According to the present invention, the ion exchange capacity of the anion exchange membrane at 30 °C is 1.26-1.99 mmol / g, preferably 1.32-1.99 mmol / g.

[0051] According to the present invention, the water absorption rate of the anion exchange membrane at 30 °C is 9%-56.9%, preferably 12.5%-56.9%.

[0052] According to the present invention, the swelling ratio of the anion exchange membrane at 30 °C is 18%-42.3%, preferably 22.3%-42.3%.

[0053] The second aspect of the present invention provides a method for preparing a double-side chain anion exchange membrane, wherein the preparation method includes:

[0054] (1) Mix the compound A represented by Formula 1, the compound B represented by Formula 2, the brominated polyphenylene ether represented by Formula 3 and an organic solvent, and then react to obtain a solution containing a prepolymer;

[0055] (2) Mix a crosslinking agent with the product of step (1) to obtain a casting solution;

[0056] (3) Coat the casting solution on a substrate and cure it to obtain the double-side chain anion exchange membrane;

[0057]

[0058] R 1 '、R 2 '、R 4 '、R 5 '、R 7 '、R 8 ' are independently H, CH 3 or CH 2 CH 3 , R 3 ' is C 8 -C 25 A straight chain or branched alkyl group; R 6 ' is C 2 -C 5 A straight chain alkylene or branched chain alkylene, X 1 and X 2 are each independently H or Br, and X 1 and X 2 At least one of them is Br; and x is 0.3-0.8.

[0059] In the present invention, the above-mentioned compound A and compound B having a specific structure are reacted with brominated polyphenylene ether, and long-chain hydrophobic alkyl side chains can be introduced into the molecular chain of polyphenylene ether, promoting the formation of a hydrophilic and hydrophobic microphase-separated aggregation structure in the obtained anion exchange membrane, and the number of active ion exchange groups of the ion exchange membrane is increased by using a diionic side chain, and the two side chains are shared to improve the performance of the ion exchange membrane. Specifically, the long-chain ionic group contained in compound A can effectively reduce the hydrophilic effect and thus reduce the attack of hydroxide, and the steric effect inhibits the approach of hydroxide ions. In addition, the β hydrogen necessary for the Hofmann degradation reaction does not exist in compound A and compound B, which can inhibit the water absorption of the ion exchange group and help to establish an ion migration channel, and successfully prepare an anion exchange membrane with a high ion exchange capacity.

[0060] Furthermore, R 1 '、R 2 '、R 4 '、R 5 '、R 7 '、R 8 'Each independently is CH 2 CH 3 or CH 3 , R 3 ' is C 10 -C 20 A straight chain or branched alkyl group; R 6 ' is C 2 -C 3 A straight chain alkylene or branched chain alkylene, X 1 and X 2 are each independently H or Br, and X1 and X 2 At least one of them is Br; and x is 0.4-0.6.

[0061] In one embodiment of the present invention, the compound A shown in Formula 1 is octadecyl dimethyl tertiary amine, that is, R 1 '、R 2 'For CH 3 , R 3 ' is C 18 of a straight chain alkyl group.

[0062] In another specific embodiment of the present invention, the compound A shown in Formula 1 is a dodecyl dimethyl tertiary amine, that is, R 1 '、R 2 'For CH 3 , R 3 ' is C 10 of a straight chain alkyl group.

[0063] In one embodiment of the present invention, the compound B shown in Formula 2 is N,N,N,N-tetramethylethylenediamine, that is, R 4 '、R 5 '、R 7 '、R 8 'Each independently is CH 3 , R 6 ' is ethylene.

[0064] In another specific embodiment of the present invention, the compound B shown in Formula 2 is N,N,N,N-tetramethylethylenediamine, that is, R 4 '、R 5 '、R 7 '、R 8 'Each independently is CH 3 , R 6 ' is a methylene group.

[0065] In the present invention, there is no particular limitation on the type of the organic solvent, as long as the brominated polyphenylene ether can be fully dissolved. For example, the organic solvent is selected from at least one of N-methylpyrrolidone, tetrahydrofuran and N,N-dimethylformamide.

[0066] According to the present invention, the weight average molecular weight of the brominated polyphenylene ether is 70000-90000 g / mol.

[0067] In the present invention, there is no particular limitation on the source of the polyphenylene ether, which can be purchased from the market or prepared in-house.

[0068] In one specific embodiment of the present invention, the brominated polyphenylene ether is prepared according to the following steps:

[0069] S1. In the presence of a solvent and a protective gas, poly (2,6-dimethyl-1,4-phenylene ether) (PPO), a brominating agent and an initiator are mixed to carry out a bromination reaction;

[0070] S2. Cooling the product obtained in step S1, adding an alcohol solution, filtering, washing, purifying and drying to obtain the brominated polyphenylene ether.

[0071] In the present invention, the molar ratio of the poly 2,6-dimethyl-1,4-phenylene ether (PPO) to the bromination reagent is 1:0.5-3, preferably 1:1-2.

[0072] In the present invention, the weight average molecular weight of the poly 2,6-dimethyl-1,4-phenylene ether is 40000-50000 g / mol.

[0073] In the present invention, the molar ratio of the poly 2,6-dimethyl-1,4-phenylene ether (PPO) to the initiator is 1:0.05-0.08, preferably 1:0.06-0.07.

[0074] In the present invention, the bromination reagent may be a conventional bromination reagent in the art, such as N-bromosuccinimide (NBS) and / or 1,3-dibromo-5,5-dimethylhydantoin (DBH).

[0075] In the present invention, the initiator may be a conventional initiator in the art, for example, azobisisobutyronitrile (AIBN) and / or azobisisoheptanenitrile (ABVN).

[0076] In the present invention, the solvent may be a conventional solvent in the art, such as chlorobenzene. There is no particular limitation on the amount of the organic solvent, as long as the poly (2,6-dimethyl-1,4-phenylene ether) (PPO) can be fully dissolved.

[0077] In the present invention, there is no particular limitation on the type of protective gas, and conventional protective gases in the art, such as nitrogen, may be used.

[0078] In the present invention, the conditions of the bromination reaction include: reaction temperature of 110-140° C., and reaction time of 2-4 h.

[0079] In the present invention, there is no particular limitation on the type of alcohol solution, and conventional alcohol solutions in the art, such as methanol solutions, can be used. There is no particular limitation on the amount of the alcohol solution, as long as the brominated polyphenylene ether can be completely precipitated. In order to further ensure that the brominated polyphenylene ether can be completely precipitated, preferably, the alcohol solution is added dropwise, more preferably, added dropwise to the product obtained in step S1 at a rate of 20-50 mL / min.

[0080] In the present invention, methanol is used to wash the filtered product.

[0081] In the present invention, the purification step comprises: re-dissolving the washed product in a first organic solvent, and washing with a second organic solvent.

[0082] In the present invention, the first organic solvent is selected from at least one of chloroform, dichloromethane and tetrahydrofuran. In the present invention, the amount of the first organic solvent used is 1000-2000 mL relative to 100 g of the washed product.

[0083] In the present invention, the second organic solvent is selected from acetone and / or butanone.

[0084] In the present invention, the amount of the second organic solvent used is 1000-2000 mL relative to 100 g of the washed product.

[0085] In a preferred embodiment of the present invention, the brominated polyphenylene ether represented by formula 3 and an organic solvent are mixed to obtain a mixed solution, and compound A represented by formula 1 and compound B represented by formula 2 are added to the mixed solution for reaction to obtain a solution containing a prepolymer.

[0086] In the present invention, the brominated polyphenylene ether is mixed with the organic solvent in advance, which can ensure that the brominated polyphenylene ether is fully dissolved and dispersed in the organic solvent, improve the dispersibility of the brominated polyphenylene ether in the mixed solution, and then allow compound A and compound B to fully contact and react with the brominated polyphenylene ether.

[0087] In the present invention, in order to control the dispersibility of the brominated polyphenylene ether, preferably, the concentration of the brominated polyphenylene ether in the mixed solution is 5wt%-20wt%, more preferably 5wt%-10wt%.

[0088] According to the present invention, the molar ratio of the compound A to the bromomethyl group in the brominated polyphenylene ether is 4-10:1.

[0089] In the present invention, when the molar ratio of compound A to the bromomethyl group in brominated polyphenylene ether is controlled to meet the above range, the long-chain ionic groups contained in compound A can effectively reduce the hydrophilic effect and thus reduce the attack of hydroxyl groups, thereby improving the hydrophobicity and compactness of the anion exchange membrane. When the molar ratio of compound A to the bromomethyl group in brominated polyphenylene ether does not meet the above range, the long-chain ionic groups contained in compound A cannot effectively reduce the hydrophilic effect and thus lead to the attack of hydroxyl groups, and the steric effect cannot inhibit the attack of hydroxyl ions, resulting in a low ion exchange capacity of the anion exchange membrane.

[0090] Furthermore, the molar ratio of the compound A to the bromomethyl group in the brominated polyphenylene ether is 4-6:1.

[0091] According to the present invention, the molar ratio of the compound B to the bromomethyl group in the brominated polyphenylene ether is 2-6:1.

[0092] In the present invention, when the molar ratio of compound B to the bromomethyl group in the brominated polyphenylene ether is controlled to meet the above range, it can be ensured that compound B can provide sufficient quaternary ammonium groups, giving the anion exchange membrane a good ion exchange capacity. When the molar ratio of compound B to the bromomethyl group in the brominated polyphenylene ether is not within the above range, it is not possible to provide suitable ion migration channels and active groups for the ion exchange membrane, resulting in a low ion exchange capacity of the anion exchange membrane.

[0093] Furthermore, the molar ratio of the compound B to the bromomethyl group in the brominated polyphenylene ether is 4-6:1.

[0094] According to the present invention, the reaction conditions include: reaction temperature of 20-40° C., and reaction time of 20-50 h.

[0095] In the present invention, under the above-mentioned specific conditions, the reaction between brominated polyphenylene ether, compound A and compound B can effectively reduce the hydrophilic effect and thus reduce the attack of hydroxide by utilizing the long-chain ionic groups, and the steric effect inhibits the approach of hydroxide ions, thereby giving the anion membrane good swelling properties and ion exchange capacity.

[0096] Furthermore, the reaction conditions include: reaction temperature of 20-30°C and reaction time of 24-48h.

[0097] According to the present invention, the molar ratio of the crosslinking agent to the brominated polyphenylene ether is 1-5:1.

[0098] In the present invention, when the amount of the crosslinking agent is controlled to meet the above range, the long-chain hydrophobic alkyl side chain groups in the polyphenylene ether skeleton can be fully converted to form cationic imidazole groups, providing active sites for ion migration, thereby improving the performance of the anion exchange membrane.

[0099] Furthermore, the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 2-4:1.

[0100] According to the present invention, the cross-linking agent is selected from at least one of the compounds having the following structures:

[0101]

[0102] Among them, R 9 ' and R 10 ' are each independently H, OH or CH 3 ; R 11 ' and R 12 ' are independently H, CH 3 or CH 2 CH3 ; X is Br or Cl, n and m are each independently an integer of 1-3; p and q are each independently an integer of 1-3.

[0103] In the present invention, the use of the above specific cross-linking agent can realize the connection of at least two polyphenylene ether molecular chains to form a stable network structure, which will not reduce the ion exchange capacity of the membrane while providing active sites for ion migration.

[0104] Furthermore, R 9 '、R 10 '、R 11 ' and R 12 ' are all H, and n, m, p and q are all 1.

[0105] In a specific embodiment of the present invention, the cross-linking agent is selected from at least one of 4,4'-dibromomethylbiphenyl, 1,4-di(bromomethyl)benzene, 4,4'-dibromobiphenyl, 4,4'-3,3'-dimethyldibromobiphenyl, 4,4'-dibromo-2,2'-dimethylbiphenyl, 1,4-di(chloromethyl)benzene, 4,4'-dichlorobiphenyl, and 2,2'-dihydroxy-4,4'-dichlorobiphenyl. Preferably, the cross-linking agent is selected from at least one of 4,4'-dibromomethylbiphenyl, 1,4-di(bromomethyl)benzene and 4,4'-dibromobiphenyl.

[0106] According to the present invention, the curing is carried out under vacuum conditions.

[0107] In the present invention, the curing of the casting solution under vacuum conditions can increase the evaporation rate of the solvent, help remove the organic solvent in the casting solution, and achieve rapid curing of the casting solution. In the present invention, the vacuum degree of the curing is 10 -2 Pa-10 -4 Pa.

[0108] According to the present invention, the curing conditions include: the curing temperature is 80-120° C.; and the curing time is 12-24 hours.

[0109] In the present invention, the curing is carried out under the above conditions, while ensuring that the anion exchange membrane will not be deformed due to heat, thereby improving the curing efficiency.

[0110] Furthermore, the curing conditions include: a curing temperature of 90-110° C.; and a curing time of 12-16 hours.

[0111] According to the present invention, the preparation method further comprises: degassing the casting solution and then coating it on a substrate.

[0112] In the present invention, the casting liquid is degassed and then coated on a substrate, and the substrate can provide good mechanical properties for the solidification process of the liquid anion membrane.

[0113] According to the present invention, the degassing includes static degassing and / or vacuum degassing.

[0114] The third aspect of the present invention provides a double side chain anion exchange membrane prepared by the above preparation method.

[0115] A fourth aspect of the present invention provides an application of the above-mentioned double side chain anion exchange membrane in a separation process.

[0116] According to the present invention, the separation process includes electrolysis of water to produce hydrogen or desalination of seawater.

[0117] The present invention will be described in detail below by way of examples. In the following examples,

[0118] All raw materials in the examples and comparative examples are commercially available products from MacLean, among which poly (2,6-dimethyl-1,4-phenylene ether) M w It is 45000g / mol.

[0119] The ion exchange capacity of the anion exchange membrane was measured by the back titration method:

[0120] At 25°C, accurately weigh the completely dried mass of the membrane to be tested, recorded as W dry . Then soak the membrane in 1mol / L NaOH solution and continue stirring for 24 hours to convert the membrane into OH type. Then take out the membrane and clean it with deionized water. Soak the OH type membrane in 0.1mol / L HCl solution for 24 hours. Use phenolphthalein as the acid-base indicator and titrate the above solution with 0.25mol / L NaOH solution. Repeat the measurement three times for each membrane, and take the average value as the final ion exchange capacity (IEC). The calculation formula of IEC is as follows:

[0121]

[0122] Among them, C H , C OH Respectively represent the concentration of hydrochloric acid and sodium hydroxide (mol / L); V H , V OH W represents the volume of hydrochloric acid consumed and the volume of NaOH consumed during titration (mL); dry It represents the film mass (g).

[0123] The water absorption of anion exchange membrane is measured by weighing method:

[0124] At 25°C, cut the film to be tested into regular strips of 1 cm × 2 cm. Wipe the surface of the film clean while it is wet. Use an electronic balance to accurately weigh the mass of the wet film, which is recorded as m. 1Use a vacuum oven to completely dry the membrane and weigh its mass, which is recorded as m. 0 Each membrane was measured three times to reduce the error. The water absorption rate (WU) is calculated as follows:

[0125]

[0126] Among them, m 0 and m 1 Represent the mass (g) of dry film and wet film respectively.

[0127] The swelling rate of the anion exchange membrane was measured by length measurement:

[0128] At 25°C, cut the film sample to be tested into a regular 1 cm × 2 cm strip, and measure the length of the dry film sample, which is recorded as l. 0 The membrane sample was immersed in deionized water for 24 hours, the surface moisture was wiped off, and the length of the membrane sample was measured and recorded as l 1 Each membrane was measured three times to reduce the error. The swelling ratio (SR) was calculated as follows:

[0129]

[0130] Among them, l 0 and l 1 Represent the length of dry film and wet film respectively (cm).

[0131] In the anion exchange membrane, the content of each structural unit is calculated by the feed amount.

[0132] Preparation Example 1

[0133] Brominated polyphenylene oxide 1(BPPO-1)

[0134] Preparation of brominated polyphenylene ether (BPPO): 9g of poly 2,6-dimethyl-1,4-phenylene ether (PPO) was dissolved in 100mL of chlorobenzene, 9.34g of N-bromosuccinimide (NBS) and 0.57g of azobisisobutyronitrile (AIBN) were added, and the reaction was stirred for 3h in an oil bath at 135°C, and a nitrogen atmosphere was maintained during the reaction. After the reactants were cooled, they were added dropwise to 1000mL of methanol to obtain a crude polymer. The polymer was filtered and washed several times with methanol. The crude product was then dissolved in 50mL of chloroform, washed with 200mL of acetone, and filtered to obtain a light yellow powder. Vacuum drying gave BPPO-1.

[0135] The brominated polyphenylene ether had a bromination rate x of 0.57 and a weight average molecular weight of 77751 g / mol.

[0136] Preparation Example 2

[0137] Brominated polyphenylene oxide 2(BPPO-2)

[0138] Preparation of brominated polyphenylene ether (BPPO): 9g of poly 2,6-dimethyl-1,4-phenylene ether (PPO) was dissolved in 100mL of chlorobenzene, 11.45g of N-bromosuccinimide (NBS) and 0.60g of azobisisobutyronitrile (AIBN) were added, and the reaction was stirred for 3h in an oil bath at 135°C, and a nitrogen atmosphere was maintained during the reaction. After the reactants were cooled, they were added dropwise to 1000mL of methanol to obtain a crude polymer. The polymer was filtered and washed several times with methanol. The crude product was then dissolved in 50mL of chloroform, washed with 200mL of acetone, and filtered to obtain a light yellow powder. Vacuum drying gave BPPO-2.

[0139] The bromination rate x of the brominated polyphenylene ether was 0.75, and the weight average molecular weight was 87652 g / mol.

[0140] Example 1

[0141] (1) BPPO-1 (2 g) of the preparation example was dissolved in N-methylpyrrolidone to form a 5 wt% solution, and octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine were added successively, and the mixture was stirred and mixed at room temperature (25° C.) for 48 hours to obtain a reaction solution containing a prepolymer; wherein the amounts of octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine were such that the molar ratio of octadecyl dimethyl tertiary amine (compound A) to the bromomethyl group in the brominated polyphenylene ether was 6:1, and the molar ratio of N,N,N,N-tetramethylethylenediamine (compound B) to the bromomethyl group in the brominated polyphenylene ether was 4.25:1.

[0142] (2) adding a cross-linking agent 4,4'-dibromomethylbiphenyl to the reaction solution to obtain a casting solution, wherein the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 4:1;

[0143] (3) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double side chain anion exchange membrane A1.

[0144] Example 2

[0145] (1) BPPO-1 (2 g) of the preparation example is dissolved in N-methylpyrrolidone to form a 5 wt% solution, and octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine are added successively, and the mixture is stirred and mixed at room temperature for 48 hours to obtain a reaction solution containing a prepolymer; wherein the amounts of octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine are such that the molar ratio of octadecyl dimethyl tertiary amine (compound A) to the bromomethyl group in the brominated polyphenylene ether is 6:1, and the molar ratio of N,N,N,N-tetramethylethylenediamine (compound B) to the bromomethyl group in the brominated polyphenylene ether is 4.25:1.

[0146] (2) adding a cross-linking agent 4,4'-dibromobiphenyl to the reaction solution to obtain a casting solution, wherein the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 3:1;

[0147] (3) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double side chain anion exchange membrane A2.

[0148] Example 3

[0149] (1) BPPO-1 (2 g) of the preparation example is dissolved in N-methylpyrrolidone to form a 5 wt% solution, and octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine are added successively, and the mixture is stirred and mixed at room temperature for 48 hours to obtain a reaction solution containing a prepolymer; wherein the amounts of octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine are such that the molar ratio of octadecyl dimethyl tertiary amine to the bromomethyl group in the brominated polyphenylene ether is 6:1, and the molar ratio of N,N,N,N-tetramethylethylenediamine to the bromomethyl group in the brominated polyphenylene ether is 4.25:1

[0150] (2) adding a cross-linking agent 1,4-di(bromomethyl)benzene to the reaction solution to obtain a casting solution, wherein the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 2:1;

[0151] (3) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double side chain anion exchange membrane A3.

[0152] Example 4

[0153] (1) BPPO-1 (2 g) of the preparation example is dissolved in N-methylpyrrolidone to form a 5 wt% solution, and octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine are added successively, and the mixture is stirred and mixed at room temperature for 48 hours to obtain a reaction solution containing a prepolymer; wherein the amounts of octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine are such that the molar ratio of octadecyl dimethyl tertiary amine to the bromomethyl group in the brominated polyphenylene ether is 5.75:1, and the molar ratio of N,N,N,N-tetramethylethylenediamine to the bromomethyl group in the brominated polyphenylene ether is 5:1.

[0154] (2) adding a cross-linking agent 4,4'-dibromobiphenyl to the reaction solution to obtain a casting solution, wherein the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 3:1;

[0155] (3) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double side chain anion exchange membrane A4.

[0156] Example 5

[0157] (1) BPPO-2 (2 g) of the preparation example was dissolved in N-methylpyrrolidone to form a 5 wt% solution, and octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine were added successively, and the mixture was stirred and mixed at room temperature (25° C.) for 48 hours to obtain a reaction solution containing a prepolymer; wherein the amounts of octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine were such that the molar ratio of octadecyl dimethyl tertiary amine (compound A) to the bromomethyl group in the brominated polyphenylene ether was 6:1, and the molar ratio of N,N,N,N-tetramethylethylenediamine (compound B) to the bromomethyl group in the brominated polyphenylene ether was 4.25:1.

[0158] (2) adding a cross-linking agent 4,4'-dibromomethylbiphenyl to the reaction solution to obtain a casting solution, wherein the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 4:1;

[0159] (3) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double side chain anion exchange membrane A5.

[0160] Example 6

[0161] (1) The brominated polyphenylene ether 1 (2 g) of the preparation example is dissolved in N-methylpyrrolidone to form a 5 wt% solution, and dodecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine are added successively, and the mixture is stirred and mixed at room temperature (25° C.) for 48 hours to obtain a reaction solution containing a prepolymer; wherein the amounts of octadecyl dimethyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine are such that the molar ratio of dodecyl dimethyl tertiary amine to the bromomethyl groups in the brominated polyphenylene ether is 6:1, and the molar ratio of N,N,N,N-tetramethylethylenediamine (compound B) to the bromomethyl groups in the brominated polyphenylene ether is 4.25:1.

[0162] (2) adding a cross-linking agent 4,4'-dibromomethylbiphenyl to the reaction solution to obtain a casting solution, wherein the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 4:1;

[0163] (3) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double side chain anion exchange membrane A6.

[0164] Example 7

[0165] (1) The brominated polyphenylene ether 1 (2 g) of the preparation example is dissolved in N-methylpyrrolidone to form a 5 wt% solution, and octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine are added successively, and the mixture is stirred and mixed at room temperature (25° C.) for 48 hours to obtain a reaction solution containing a prepolymer; wherein the amounts of octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine are such that the molar ratio of octadecyl dimethyl tertiary amine (compound A) to the bromomethyl groups in the brominated polyphenylene ether is 6:1, and the molar ratio of N,N,N,N-tetramethylethylenediamine to the bromomethyl groups in the brominated polyphenylene ether is 4.25:1.

[0166] (2) adding a cross-linking agent 4,4'-dibromomethylbiphenyl to the reaction solution to obtain a casting solution, wherein the amount of the cross-linking agent is such that the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 4:1;

[0167] (3) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double side chain anion exchange membrane A7.

[0168] Example 8

[0169] (1) BPPO-1 (2 g) of the preparation example was dissolved in N-methylpyrrolidone to form a 5 wt% solution, and octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine were added successively, and the mixture was stirred and mixed at room temperature (25° C.) for 48 hours to obtain a reaction solution containing a prepolymer; wherein the amounts of octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine were such that the molar ratio of octadecyl dimethyl tertiary amine (compound A) to the bromomethyl group in the brominated polyphenylene ether was 8:1, and the molar ratio of N,N,N,N-tetramethylethylenediamine (compound B) to the bromomethyl group in the brominated polyphenylene ether was 4.25:1.

[0170] (2) adding a cross-linking agent 4,4'-dibromomethylbiphenyl to the reaction solution to obtain a casting solution, wherein the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 4:1;

[0171] (3) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double side chain anion exchange membrane A8.

[0172] Example 9

[0173] (1) BPPO-1 (2 g) of the preparation example is dissolved in N-methylpyrrolidone to form a 5 wt % solution, and octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine are added successively, and the mixture is stirred and mixed at room temperature (25° C.) for 48 hours to obtain a reaction solution containing a prepolymer; wherein the amounts of octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine are such that the molar ratio of octadecyl dimethyl tertiary amine (compound A) to the bromomethyl group in the brominated polyphenylene ether is 6:1, and the molar ratio of N,N,N,N-tetramethylethylenediamine (compound B) to the bromomethyl group in the brominated polyphenylene ether is 3:1.

[0174] (2) adding a cross-linking agent 4,4'-dibromomethylbiphenyl to the reaction solution to obtain a casting solution, wherein the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 4:1;

[0175] (3) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double side chain anion exchange membrane A9.

[0176] Example 10

[0177] (1) BPPO-1 (2 g) of the preparation example was dissolved in N-methylpyrrolidone to form a 5 wt% solution, and octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine were added successively, and the mixture was stirred and mixed at room temperature (25° C.) for 48 hours to obtain a reaction solution containing a prepolymer; wherein the amounts of octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine were such that the molar ratio of octadecyl dimethyl tertiary amine (compound A) to the bromomethyl group in the brominated polyphenylene ether was 6:1, and the molar ratio of N,N,N,N-tetramethylethylenediamine (compound B) to the bromomethyl group in the brominated polyphenylene ether was 4.25:1.

[0178] (2) adding a cross-linking agent 4,4'-dibromomethylbiphenyl to the reaction solution to obtain a casting solution, wherein the amount of the cross-linking agent is such that the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 1.25:1;

[0179] (3) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double side chain anion exchange membrane A10.

[0180] Embodiment 11

[0181] (1) BPPO-1 (2 g) of the preparation example was dissolved in N-methylpyrrolidone to form a 5 wt% solution, and octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine were added successively, and the mixture was stirred and mixed at room temperature (25° C.) for 48 hours to obtain a reaction solution containing a prepolymer; wherein the amounts of octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine were such that the molar ratio of octadecyl dimethyl tertiary amine (compound A) to the bromomethyl group in the brominated polyphenylene ether was 2:1, and the molar ratio of N,N,N,N-tetramethylethylenediamine (compound B) to the bromomethyl group in the brominated polyphenylene ether was 4.25:1.

[0182] (2) adding a cross-linking agent 4,4'-dibromomethylbiphenyl to the reaction solution to obtain a casting solution, wherein the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 4:1;

[0183] (3) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double side chain anion exchange membrane A11.

[0184] Example 12

[0185] (1) BPPO-1 (2 g) of the preparation example is dissolved in N-methylpyrrolidone to form a 5 wt % solution, and octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine are added successively, and the mixture is stirred and mixed at room temperature (25° C.) for 48 hours to obtain a reaction solution containing a prepolymer; wherein the amounts of octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine are such that the molar ratio of octadecyl dimethyl tertiary amine (compound A) to the bromomethyl group in the brominated polyphenylene ether is 6:1, and the molar ratio of N,N,N,N-tetramethylethylenediamine (compound B) to the bromomethyl group in the brominated polyphenylene ether is 1:1.

[0186] (2) adding a cross-linking agent 4,4'-dibromomethylbiphenyl to the reaction solution to obtain a casting solution, wherein the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 4:1;

[0187] (3) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double side chain anion exchange membrane A12.

[0188] Embodiment 13

[0189] (1) BPPO-1 (2 g) of the preparation example was dissolved in N-methylpyrrolidone to form a 5 wt% solution, and octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine were added successively, and the mixture was stirred and mixed at room temperature (25° C.) for 48 hours to obtain a reaction solution containing a prepolymer; wherein the amounts of octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine were such that the molar ratio of octadecyl dimethyl tertiary amine (compound A) to the bromomethyl group in the brominated polyphenylene ether was 6:1, and the molar ratio of N,N,N,N-tetramethylethylenediamine (compound B) to the bromomethyl group in the brominated polyphenylene ether was 4.25:1.

[0190] (2) adding a cross-linking agent 4,4'-dibromomethylbiphenyl to the reaction solution to obtain a casting solution, wherein the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 8:1;

[0191] (3) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double side chain anion exchange membrane A13.

[0192] Comparative Example 1

[0193] (1) BPPO-2 (2 g) of the preparation example was dissolved in N-methylpyrrolidone to form a 5 wt% solution, octadecyl dimethyl tertiary amine was added, and the mixture was stirred and reacted at room temperature for 48 hours to obtain a casting solution, wherein the amount of octadecyl dimethyl tertiary amine was such that the molar ratio of octadecyl dimethyl tertiary amine (compound A) to the bromomethyl group in the brominated polyphenylene ether was 6:1.

[0194] (2) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain an anion exchange membrane D1.

[0195] Comparative Example 2

[0196] (1) The brominated polyphenylene ether 1 (2 g) of the preparation example was dissolved in N-methylpyrrolidone to form a 5 wt% solution, N,N,N,N-tetramethylethylenediamine was added, and the mixture was stirred and reacted at room temperature for 48 hours to obtain a casting solution, wherein the amount of N,N,N,N-tetramethylethylenediamine was such that the molar ratio of N,N,N,N-tetramethylethylenediamine (compound B) to the bromomethyl group in the brominated polyphenylene ether was 4.25:1.

[0197] (2) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain an anion exchange membrane D2.

[0198] Comparative Example 3

[0199] (1) The brominated polyphenylene ether 1 (2 g) of the preparation example was dissolved in N-methylpyrrolidone to form a 5 wt % solution, and tert-amylamine (in Formula 1, R 1 '、R 2 'For H, R 3 ' is C 5 The invention relates to a prepolymer-containing reaction liquid; wherein the molar ratio of tert-amylamine to the bromomethyl group in the brominated polyphenylene ether is 6:1, and the molar ratio of N,N,N,N-tetramethylmethanediamine to the bromomethyl group in the brominated polyphenylene ether is 4.25:1.

[0200] (2) adding a cross-linking agent 4,4'-dibromomethylbiphenyl to the reaction solution to obtain a casting solution, wherein the molar ratio of the cross-linking agent to the brominated polyphenylene ether is 4:1;

[0201] (3) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double-sided short-chain anion exchange membrane D3.

[0202] Comparative Example 4

[0203] (1) BPPO-1 (2 g) of the preparation example was dissolved in N-methylpyrrolidone to form a 5 wt% solution, and octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine were added successively, and the mixture was stirred and mixed at room temperature (25° C.) for 48 hours to obtain a reaction solution containing a prepolymer; wherein the amounts of octadecyl dimethyl tertiary amine and N,N,N,N-tetramethylethylenediamine were such that the molar ratio of octadecyl dimethyl tertiary amine (compound A) to the bromomethyl group in the brominated polyphenylene ether was 6:1, and the molar ratio of N,N,N,N-tetramethylethylenediamine (compound B) to the bromomethyl group in the brominated polyphenylene ether was 4.25:1.

[0204] (2) After degassing, the casting solution was poured onto a glass plate and scraped with a scraper to obtain a liquid film layer. The film layer was cured in a vacuum oven at 80° C. for 12 hours and peeled off from the glass plate to obtain a double-side chain anion exchange membrane D4.

[0205] The content of each group in the anion exchange membranes of the embodiments and comparative examples was tested, and the results are shown in Table 1.

[0206] Table 1

[0207] The group represented by formula II (%) The group represented by formula III (%) Br(％) Ar structure (%) Example 1 20.8 44.3 1.8 8.3 Example 2 21.4 43.8 1.7 7.4 Example 3 21.6 42.1 1.4 6.9 Example 4 18.6 46.3 1.6 7.2 Example 5 32.5 56.1 1.9 8.2 Example 6 20.6 44.2 1.8 8.1 Example 7 28.7 18.5 1.2 8.5 Example 8 36.7 41.2 1.8 6.5 Example 9 22.3 25.6 1.4 7.3 Example 10 26.5 40.5 1.3 5.1 Embodiment 11 8.3 59.8 4.9 9.9 Example 12 39.7 12.3 4.7 10.3 Example 13 38.6 21.6 4.4 18.3 Comparative Example 1 48.9 - 6.5 - Comparative Example 2 - 66.4 5.5 - Comparative Example 3 8.9 63.8 7.8 17.8 Comparative Example 4 42.6 12.5 7.5 -

[0208] The ion exchange capacity, water absorption rate and swelling degree of the anion exchange membranes prepared in the examples and comparative examples were tested, and the results are shown in Table 2.

[0209] Table 2

[0210] Ion exchange capacity (mmol / g) Water absorption (%) Swelling rate (%) Example 1 1.59 12.5 22.3 Example 2 1.47 21.4 23.1 Example 3 1.99 56.8 39.8 Example 4 1.54 22.8 24.3 Example 5 1.31 11.3 21.5 Example 6 1.34 17.5 42.3 Example 7 1.25 18.3 40.2 Example 8 1.29 24.3 30.2 Example 9 1.30 10.6 24.3 Example 10 1.26 30.2 36.4 Embodiment 11 1.16 9.2 18.6 Example 12 1.18 10.3 19.3 Example 13 1.19 11.2 20.1 Comparative Example 1 0.99 7.9 8.4 Comparative Example 2 1.15 8.5 13.2 Comparative Example 3 1.13 8.2 9.7 Comparative Example 4 0.89 78.9 86.3

[0211] It can be seen from the results in Table 2 that, compared with the comparative example, the anion exchange membrane containing two side chains prepared in the present invention has a relatively high ion exchange capacity and a suitable water absorption rate.

[0212] Figure 2 is the Fourier transform infrared spectrum (FTIR) of the ion exchange membranes of Example 3, Comparative Example 1 and Comparative Example 2, Figure 2 It can be seen that at 2920-2850cm -1 The stretching vibration of the saturated CH bonds on the side chain alkanes in different chemical environments shows multi-peak signals. 2 The radical will cause CH at 720cm -1 The characteristic absorption of the rocking vibration at the place. Comparative Example 1 contains multiple consecutive CH 2 Group, CH contained in Comparative Example 2 2The fewer groups, the more obvious it is in the absorption peak area at the above position: when the molar amount of the added reagent is the same, the peak area in Comparative Example 1 is larger, and the peak area in Comparative Example 2 is smaller. When both are added at the same time, the peak area is between the two. Figure 2 It was confirmed that two side chains were introduced simultaneously into the anion exchange membrane in Example 3 of the present invention.

[0213] Figure 3 The following are surface SEM images and cross-sectional SEM images of the ion exchange membranes prepared in Examples 1-3 and Comparative Example 1. Specifically, Figure 3 (a) is a surface SEM image of the ion exchange membrane of Example 3, Figure 3 (e) is a cross-sectional SEM image of the ion exchange membrane of Example 3, Figure 3 (b) is a surface SEM image of the ion exchange membrane of Example 2, Figure 3 (f) is a cross-sectional SEM image of the ion exchange membrane of Example 2, Figure 3 (c) is a surface SEM image of the ion exchange membrane of Example 1, Figure 3 (g) is a cross-sectional SEM image of the ion exchange membrane of Example 1, Figure 3 (d) is a surface SEM image of the ion exchange membrane of Comparative Example 1, Figure 3 (h) is a cross-sectional SEM image of the ion exchange membrane of Comparative Example 1.

[0214] Depend on Figure 3 It can be seen from the cross-sectional view that, compared with Comparative Example 1, gradually clear microphase separation structures are observed on the surfaces of the anion exchange membranes prepared in Examples 1-3, and the structures become more obvious as the crosslinking agent content increases.

[0215] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A double side chain anion exchange membrane, It is characterized in that The anion exchange membrane comprises a plurality of polyphenylene ether molecular chains; the polyphenylene ether molecular chains have a structure as shown in Formula I; Q1, Q2, Q3 and Q4 are each independently a group represented by formula II, a group represented by formula III, Br or H; and at least two of Q1, Q2, Q3 and Q4 are a group represented by formula II and a group represented by formula III; At least two polyphenylene ether molecular chains are connected via an Ar structure from a cross-linking agent; Among them, R 1 , R 2 , R 4 , R 5 , R 7 , R 8 Each independently is H, CH 3 or CH 2 CH 3 , R 3 C 8 -C 25 A straight chain or branched alkyl group; R 6 C 2 -C 5 A straight chain alkylene group or a branched chain alkylene group; x is 0.3-0.

8.

2. The double side chain anion exchange membrane according to claim 1, in, R 1 , R 2 , R 4 , R 5 , R 7 , R 8 Each independently is CH 2 CH 3 or CH 3 ; R 3 C 10 -C 20 A straight chain or branched alkyl group; R 6 C 2 -C 3 A straight chain alkylene group or a branched chain alkylene group; x is 0.4-0.

6.

3. The double side chain anion exchange membrane according to claim 1 or 2, in, The Ar structure is selected from at least one of the following: Among them, R 9 and R 10 Each independently is H, OH or CH 3 ; R 11 and R 12 Each independently is H, CH 3 or CH 2 CH 3 ; n and m are each independently an integer of 1-3; p and q are each independently an integer of 1-3; Preferably, R 9 , R 10 , R 11 and R 12 Each is H, and n, m, p and q are all 1.

4. The double side chain anion exchange membrane according to any one of claims 1 to 3, in, Based on the total molar amount of the anion exchange membrane, the molar content of the group represented by formula II is 10-40%, the molar content of the group represented by formula III is 20-60%, the molar content of Br is 0-5%, and the molar content of the Ar structure is 5-15%; Preferably, based on the total molar amount of the anion exchange membrane, the molar content of the group represented by formula II is 10-30%, the molar content of the group represented by formula III is 30-50%, the molar content of Br is 0.2-2%, and the molar content of the Ar structure is 6-9%.

5. The double side chain anion exchange membrane according to any one of claims 1 to 4, in, The anion exchange membrane has an ion exchange capacity of 1.26-1.99 mmol / g at 30°C; Preferably, the water absorption rate of the anion exchange membrane at 30° C. is 9%-56.9%; Preferably, the swelling ratio of the anion exchange membrane at 30° C. is 18%-42.3%.

6. A method for preparing a double side chain anion exchange membrane, It is characterized in that The preparation method comprises: (1) mixing compound A represented by formula 1, compound B represented by formula 2, brominated polyphenylene ether represented by formula 3, and an organic solvent, and reacting the mixture to obtain a solution containing a prepolymer; (2) mixing a cross-linking agent with the product of step (1) to obtain a casting solution; (3) coating the casting solution on a substrate and curing the substrate to obtain the double side chain anion exchange membrane; R 1 '、R 2 '、R 4 '、R 5 '、R 7 '、R 8 ' are independently H, CH 3 or CH 2 CH 3 , R 3 ' is C 8 -C 25 A straight chain or branched alkyl group; R 6 ' is C 2 -C 5 A straight chain alkylene or branched chain alkylene, X 1 and X 2 are each independently H or Br, and X 1 and X 2 At least one of them is Br; and x is 0.3-0.

8.

7. The preparation method according to claim 6, in, The organic solvent is selected from at least one of N-methylpyrrolidone, tetrahydrofuran and N,N-dimethylformamide; Preferably, the weight average molecular weight M of the brominated polyphenylene ether is w 70000-90000 g / mol; Preferably, the brominated polyphenylene ether represented by Formula 3 and an organic solvent are mixed to obtain a mixed solution, and the compound A represented by Formula 1 and the compound B represented by Formula 2 are added to the mixed solution for reaction to obtain a solution containing a prepolymer; Preferably, the concentration of brominated polyphenylene ether in the mixed solution is 5wt%-20wt%.

8. The preparation method according to claim 6 or 7, in, The molar ratio of the compound A to the bromomethyl group in the brominated polyphenylene ether is 4-10:1; Preferably, the molar ratio of the compound B to the bromomethyl group in the brominated polyphenylene ether is 2-6:1; Preferably, the reaction conditions include: reaction temperature of 20-40° C., and reaction time of 20-50 h.

9. The preparation method according to any one of claims 6 to 8, in, The molar ratio of the crosslinking agent to the brominated polyphenylene ether is 1-5:1; Preferably, the cross-linking agent is selected from at least one of the compounds having the following structures: Among them, R 9 ' and R 10 ' are each independently H, OH or CH 3 ; R 11 ' and R 12 ' are independently H, CH 3 or CH 2 CH 3 ; X is Br or Cl, n and m are each independently an integer of 1-3; p and q are each independently an integer of 1-3; Preferably, R 9 '、R 10 '、R 11 ' and R 12 ' are all H, and n, m, p and q are all 1.

10. The preparation method according to any one of claims 6 to 9, in, Carrying out the curing under vacuum conditions; Preferably, the curing conditions include: a curing temperature of 80-120° C., preferably 90-110° C.; and a curing time of 12-24 h, preferably 12-16 h.

11. The preparation method according to any one of claims 6 to 10, in, The preparation method further comprises: Degassing the casting solution and then coating it on a substrate; Preferably, the degassing includes static degassing and / or vacuum degassing.

12. A double side chain anion exchange membrane prepared by the preparation method according to any one of claims 6 to 11.

13. Use of the double side chain anion exchange membrane according to any one of claims 1 to 6 and 12 in a separation process.

14. The use according to claim 13, in, The separation process includes electrolysis of water to produce hydrogen or desalination of seawater.

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