SEBS (styrene-ethylene-butylene-styrene) cross-linked composite anion exchange membrane as well as preparation method and application thereof

Abstract

The invention relates to an SEBS cross-linked composite anion exchange membrane as well as a preparation method and application thereof. The SEBS cross-linked composite anion exchange membrane comprises an active layer and a porous support layer, the active layer comprises a cross-linked polymer, the cross-linked polymer comprises a linear SEBS unit and a cross-linking unit, the linear SEBS unit comprises a linear carbon main chain and an S side group connected to the linear carbon main chain, the S side group comprises a benzene ring, and the benzene ring is connected with methylene or acyl; the crosslinking unit comprises at least three quaternary ammonium type N onium ions which are indirectly and covalently connected with a benzene ring in an S side group, and two positively charged N in the at least two quaternary ammonium type N onium ions are connected through [-CH2-(A) X-CH2-] U or-(CH2) Y-CH2-. The active layer containing the three-dimensional network structure is compounded with the porous supporting layer, so that the composite membrane can bear physical stress in operation of a use scene, and the integrity and long-term performance stability of the membrane structure are further improved.

Description

Technical Field

[0001] This invention relates to the field of polymer membrane materials technology, and in particular to SEBS cross-linked composite anion exchange membranes, their preparation methods, and applications. Background Technology

[0002] Anion exchange membranes (AEMs), as a key functional membrane material, have significant application value in energy conversion and chemical separation, playing an irreplaceable role, particularly in fuel cells, water electrolysis for hydrogen production, CO2 reduction, and water treatment. The basic function of anion exchange membranes is to selectively transport anions in a liquid environment, while also acting as a charge carrier and an electro-gas barrier. Their performance directly affects energy conversion efficiency and system stability.

[0003] In practical applications, anion exchange membranes need to simultaneously meet multiple requirements, including high ion conductivity, excellent dimensional stability, and long-term chemical stability. However, these performance indicators are often difficult to achieve simultaneously. Traditional homogeneous membrane systems experience significant degradation in mechanical properties under operating conditions due to factors such as hydration, making them unable to meet long-term application needs.

[0004] To address this issue, researchers have explored various methods, including chemical cross-linking, inorganic nanoparticle doping, and the creation of reinforcing structures.

[0005] Currently, the development of composite anion exchange membranes mainly faces the following technical challenges: poor compatibility between the filler and the polymer matrix leads to uneven distribution of the filler within the membrane, affecting its overall performance; the membrane's stability gradually decreases during long-term use; and the pursuit of high mechanical properties often results in a reduction in gas barrier properties or ion conductivity. For example, while some composite membranes prepared by introducing metal-organic frameworks (MOFs) have improved ion conductivity to some extent, the interfacial compatibility problem between the filler and the polymer remains fundamentally unresolved. While composite membranes reinforced with mesh fabrics offer improved mechanical properties, they often result in an uneven membrane surface, making them prone to contaminant adhesion and reducing the membrane's antifouling ability. Summary of the Invention

[0006] Therefore, it is necessary to provide SEBS cross-linked composite anion exchange membranes that combine high ionic conductivity and long-term stability, as well as their preparation methods and applications.

[0007] In one aspect, the present invention provides an EBS cross-linked composite anion exchange membrane, comprising an active layer and a porous support layer;

[0008] The active layer includes a crosslinked polymer, which includes a linear SEBS unit and a crosslinking unit. The linear SEBS unit includes a linear carbon backbone and an S side group attached to the linear carbon backbone. The S side group includes a benzene ring, and the benzene ring is attached with a methylene group or an acyl group.

[0009] The crosslinking unit comprises at least three quaternary ammonium N-onium ions indirectly covalently linked to the benzene ring in the S-side group, wherein two of the positively charged N-ions in the at least two quaternary ammonium N-onium ions are connected via [-CH2-(A)]. X -CH2-] U Or -(CH2) Y -CH2- is connected; wherein, each A is independently selected from a carbon atom, an oxygen atom, or a benzene ring, and (A) X In this case, the oxygen atom is not adjacent to any other oxygen atom, U is an integer selected from 1 to 10, X is an integer selected from 0 to 5, and Y is an integer selected from 1 to 10.

[0010] In this context, the positively charged N in the quaternary ammonium-type N-onium ion participates in the formation of two diazabicyclic rings, or...

[0011] The positively charged N in the quaternary ammonium Nionium ion is connected to R1, R2, and R3, wherein R1 and R2 are each independently C. 1-3 Alkyl group, R3 is a group containing a quaternary ammonium salt.

[0012] In some embodiments, the crosslinked polymer satisfies at least one of the following characteristics:

[0013] The diazabicyclo ring is a 1,4-diazabicyclo[2.2.2]octane ring;

[0014] The positively charged N in the quaternary ammonium-type Nionium ion combines with the halide anion to form an ion pair.

[0015] In some embodiments, the crosslinking unit comprises any one or more of an alkyl azabicyclic group having the structure shown in Formula I and an alkyl polyamine group having the structure shown in Formula II:

[0016] Formula I

[0017] Formula II

[0018] In the formula, * represents the site connected to the S side base, X is any integer selected from 0-5, U is any integer selected from 1-10, and Y1, Y2 and Y3 are each independently any integer selected from 1-10.

[0019] In some embodiments, the active layer includes at least one of the following features:

[0020] The mass ratio of the SEBS unit to the crosslinking unit is 1:(0.3-0.7).

[0021] The thickness of the active layer is 40 μm - 100 μm.

[0022] In some embodiments, the porous support layer includes at least one of the following features:

[0023] The porous support layer is made of any one or more of polyetheretherketone, polyphenylene sulfide, polyethylene, polyethylene terephthalate, polypropylene, or polytetrafluoroethylene.

[0024] The mesh size of the porous support layer is 10-200;

[0025] The thickness of the porous support layer is 20 μm-80 μm, and optionally, the thickness of the porous support layer is 30 μm-50 μm.

[0026] The second aspect of this application provides a method for preparing an SEBS cross-linked composite anion exchange membrane, comprising the following steps:

[0027] A functionalized SEBS is provided; wherein the functionalized SEBS comprises an SEBS unit and a functional group attached to a benzene ring contained in a side group of the SEBS unit, the functional group being a chloromethyl group or an activated acyl group, the activated acyl group containing a reactive group capable of nitrifying a tertiary amine N;

[0028] The functionalized SEBS, crosslinking agent, and first solvent are mixed and subjected to a quaternization crosslinking reaction to obtain a crosslinked polymer solution; wherein the crosslinking agent is an alkylazabicyclohexane or an alkylpolyamine.

[0029] The crosslinked polymer solution is disposed on at least one surface of the porous support layer, and the solvent is removed;

[0030] The composite membrane obtained after removing the solvent is subjected to ion exchange in an alkaline solution to prepare any of the above-mentioned SEBS cross-linked composite anion exchange membranes.

[0031] In some embodiments, the step of providing the functionalized SEBS includes at least one of the following features:

[0032] The functional group is chloromethyl, and the functionalized SEBS is prepared by a method including the following steps: mixing SEBS, chloromethylating agent, first catalyst and second solvent, carrying out chloromethylation reaction, and obtaining chloromethylated SEBS after first purification treatment;

[0033] The functional group is an activated acyl group, and the functionalized SEBS is prepared by a method including the following steps: mixing SEBS, acylation reagent, second catalyst and third solvent, carrying out acylation reaction, and obtaining acylated SEBS by second purification treatment.

[0034] In some embodiments, the step of providing the functionalized SEBS includes at least one of the following features:

[0035] The chloromethylating agent includes any one or more of formaldehyde, trioxymethylene, paraoxymethylene, chloromethyl ether, dichloromethyl ether, chloromethylalkyl ether, and trimethylchlorosilane;

[0036] The acylation reagent includes any one or more of acyl halides, acid anhydrides, carboxylic acids, and amides, and the acylation reagent contains a reactive group capable of nitrifying tertiary amine N.

[0037] The first catalyst and the second catalyst are each independently selected from any one or more of AlCl3, FeCl3, BF3, SnCl4, ZnCl2, HCl, H2SO4, H3PO4 and CH3COOH;

[0038] The second solvent and the third solvent are each independently selected from any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dichloromethane, toluene, and chloroform;

[0039] The chloromethylation reaction was carried out at a temperature of 0℃-60℃ for 24 h-72 h.

[0040] The acylation reaction was carried out at a temperature of 0℃-60℃ for a time of 24 h-72 h.

[0041] The first purification process or the second purification process includes precipitation and washing processes; optionally, the detergent used in the precipitation and washing processes is selected from any one or more of water, ethanol, methanol, diethyl ether and ethyl acetate.

[0042] In some embodiments, the method for preparing the SEBS cross-linked composite anion exchange membrane described above includes at least one of the following features:

[0043] The first solvent is selected from any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dichloromethane, toluene, and chloroform;

[0044] The mass ratio of the functionalized SEBS to the crosslinking agent is 1:(0.3-0.7).

[0045] The temperature for the quaternization crosslinking reaction is 20℃-80℃;

[0046] The quaternization crosslinking reaction takes 12 h to 48 h;

[0047] The solid content of the crosslinked polymer solution is 5 wt%-30 wt%.

[0048] The alkali in the alkaline solution includes at least one of potassium hydroxide, sodium hydroxide, and calcium hydroxide.

[0049] The third aspect of this application provides the application of an SEBS cross-linked composite anion exchange membrane prepared by any of the above-described methods in the preparation of fuel cells or electrolysis devices.

[0050] The active layer of the aforementioned SEBS cross-linked composite anion exchange membrane comprises a cross-linked polymer with a three-dimensional network structure formed by linear SEBS units and cross-linking units. This three-dimensional network structure is a stable three-dimensional covalent cross-linked network existing between polymer chains. This allows the active layer of the SEBS cross-linked composite anion exchange membrane to not only possess good electrical conductivity but also significantly reduce water absorption and swelling, enabling the membrane to maintain good dimensional stability even in high humidity environments and helping to slow down the degradation of quaternary ammonium groups under strongly alkaline conditions. Furthermore, by combining the active layer containing the three-dimensional network structure with a porous support layer, the porous support layer provides strong mechanical support, inhibiting membrane expansion and enabling the composite membrane to withstand the physical stresses during operation in scenarios such as fuel cells or electrolyzers, further improving the integrity of the membrane structure and long-term performance stability.

[0051] In the three-dimensional network structure formed by the cross-linked polymer of the active layer in the aforementioned SEBS cross-linked composite anion exchange membrane, the flexible alkyl chains used as spacers significantly improve the mobility of the polymer chains compared to polymers formed by short-chain or rigid cross-linking agents. This facilitates better aggregation of hydrophilic ionic groups, thereby forming a clearer microphase separation structure and a more efficient ion transport channel. Attached Figure Description

[0052] Figure 1 This is a comparison diagram of the mechanical strength of the anion exchange membranes prepared in Example 2 and Comparative Example 1;

[0053] Figure 2 The polarization curves of the anion exchange membranes prepared in Example 2 and Comparative Example 1 when applied to an electrolysis device are shown.

[0054] Figure 3 The electrolytic stability test curve of the anion exchange membrane prepared in Example 2;

[0055] Figure 4 The NMR spectrum is shown for the acylated SEBS obtained in Example 2. Detailed Implementation

[0056] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0058] Traditional composite membrane materials, such as those widely used in alkaline water electrolysis hydrogen production units, which use polyphenylene sulfide (PPS) fabric as a substrate and are coated with a mixture of polymers (such as polysulfone) and inorganic oxides (such as zirconium oxide), have the main advantage of using a rigid support layer to ensure mechanical strength and a hydrophilic surface coating to promote ion transport. The structure of such composite membranes can generally be viewed as a "rigid-flexible" strategy, where the rigid porous support layer (or ceramic coating) is responsible for maintaining dimensional and thermal stability, while the flexible polymer coating or matrix provides a certain degree of toughness and interfacial compatibility. However, this physical composite approach also brings inherent challenges: on the one hand, the interfacial compatibility between the inorganic ceramic phase and the organic polymer phase is often poor, and there is a risk of coating peeling (powdering) during long-term use, affecting the membrane's durability; on the other hand, traditional polysulfone materials themselves have weak chemical functionality, and their modification is usually limited to physical blending or surface coating, restricting further improvements in ion conduction efficiency and the guarantee of long-term operational stability.

[0059] To address this issue, this application provides at least one SEBS cross-linked composite anion exchange membrane, its preparation method, and its application.

[0060] According to a typical embodiment of this application, a SEBS cross-linked composite anion exchange membrane is provided, comprising an active layer and a porous support layer; the active layer comprises a cross-linked polymer, the cross-linked polymer comprising linear SEBS units and cross-linking units, the linear SEBS unit comprising a linear carbon backbone and S side groups connected to the linear carbon backbone, the S side groups comprising benzene rings, the benzene rings being connected to methylene or acyl groups; the cross-linking units comprise at least three quaternary ammonium N-onium ions indirectly covalently linked to the benzene rings in the S side groups, two of the at least two quaternary ammonium N-onium ions having two positively charged N atoms connected to [-CH2-(A)]. X -CH2-] U Or -(CH2) Y -CH2- is connected; wherein, each A is independently selected from a carbon atom, an oxygen atom, or a benzene ring, and (A) X The oxygen atom is not adjacent to other oxygen atoms, U is an integer selected from 1 to 10, X is an integer selected from 0 to 5, and Y is an integer selected from 1 to 10; wherein, the positively charged N in the quaternary ammonium N-onium ion participates in the formation of two diazabicyclic rings, or, the positively charged N in the quaternary ammonium N-onium ion is connected to R1, R2, and R3, wherein R1 and R2 are each independently C 1-3 Alkyl group, R3 is a group containing a quaternary ammonium salt.

[0061] The active layer of this application comprises a cross-linked polymer with a three-dimensional network structure formed by linear SEBS units and cross-linking units. This three-dimensional network structure is a stable three-dimensional covalent cross-linked network existing between polymer chains. This allows the active layer of the SEBS cross-linked composite anion exchange membrane to not only have good electrical conductivity but also significantly reduce water absorption and swelling, enabling the membrane to maintain good dimensional stability even in high humidity environments and helping to slow down the degradation of quaternary ammonium groups under strongly alkaline conditions. Furthermore, by compositing the active layer containing the three-dimensional network structure with a porous support layer, the porous support layer provides strong mechanical support, inhibits membrane expansion, and enables the composite membrane to withstand the physical stresses during operation in application scenarios such as fuel cells or electrolyzers, further improving the integrity of the membrane structure and long-term performance stability.

[0062] In the three-dimensional network structure formed by the cross-linked polymer of the active layer in the aforementioned SEBS cross-linked composite anion exchange membrane, the flexible alkyl chains used as spacers significantly improve the mobility of the polymer chains compared to polymers formed by short-chain or rigid cross-linking agents. This facilitates better aggregation of hydrophilic ionic groups, thereby forming a clearer microphase separation structure and a more efficient ion transport channel.

[0063] In this application, SEBS represents a styrene-ethylene-butene-styrene block copolymer, chloromethylated SEBS represents a copolymer containing benzyl chloride formed by chloromethylation of SEBS, and acylated SEBS represents a copolymer containing acyl groups and reactive groups capable of nitrifying tertiary amine N formed by acylation of SEBS.

[0064] For example, the crosslinked polymer described above may have the structure shown in formula (1) or formula (2) below, where R represents a crosslinking unit. It can be understood that the positional relationship between the crosslinking unit R and the linear SEBS unit is shown in formula (1) or formula (2) below, and the structure of the S side group of the linear SEBS unit is not limited to the groups described above.

[0065]

[0066] Equation (1)

[0067]

[0068] Equation (2)

[0069] In some embodiments, the number of methylene groups in the S-side group is 1 to 20, such as 1, 3, 5, 7, 9, 10, 12, 14, 16, 18, 20, etc. Understandably, the S-side group may also include other groups.

[0070] In some embodiments, the diazabicyclone is a (1,4-diazabicyclo[2.2.2]octane ring, i.e. .

[0071] In some embodiments, the positively charged N in the quaternary ammonium Nionium ion combines with a halide anion to form an ion pair. For example, the halide anion can be a fluoride ion, chloride ion, bromide ion, or iodide ion, etc. In some embodiments of this application, the crosslinking unit includes an alkyl-azabicyclic group having the structure shown in Formula I:

[0072] Formula I

[0073] In the formula, * represents the site connected to the S side group, A represents any one or more of carbon atoms, oxygen atoms, or benzene rings, X is any integer selected from 0-5, and U is any integer from 1-10. For example, U can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. Understandably, when the value of U is greater than 1, multiple A's can be the same or different, and there will not be two or more oxygen atoms directly connected.

[0074] The crosslinking units of the alkylazabicyclic structures described above have multiple crosslinking sites and high reactivity. The resulting active layer with a three-dimensional network structure not only has better ion conductivity but also helps to improve the long-term stability of the SEBS crosslinked composite anion exchange membrane.

[0075] In some embodiments, the crosslinking unit includes an alkyl polyamine group having the structure shown in Formula II, and the active layer of the crosslinking unit having this structure can better balance high ionic conductivity and long-term stability.

[0076] Formula II

[0077] In the formula, * represents the site connected to the S side base, Y1, Y2, and Y3. For example, Y1, Y2, and Y3 are each independently 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. Understandably, the values ​​of Y1, Y2, and Y3 can be the same or different.

[0078] In some embodiments, the mass ratio of SEBS units to crosslinking units is 1:0.3-0.7; non-limitingly, it can be 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, etc., and the resulting three-dimensional covalent crosslinking network is beneficial to further improve the performance of SEBS crosslinked composite anion exchange membrane.

[0079] In some embodiments, the thickness of the active layer is 40 μm-100 μm. Non-limitingly, the thickness of the active layer can be 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm.

[0080] In some embodiments, the porous support layer includes a mesh material. Optionally, the material of the porous support layer is any one or more of polyetheretherketone, polyphenylene sulfide, polyethylene, polyethylene terephthalate, polypropylene, or polytetrafluoroethylene.

[0081] In some embodiments, the mesh count of the porous support layer is 10-200. Non-limitingly, the mesh count can be 10, 30, 50, 80, 100, etc.

[0082] In some embodiments, the thickness of the porous support layer is 20 μm-80 μm, and optionally, the thickness of the porous support layer is 30 μm-50 μm. Non-limitingly, the thickness of the porous support layer can be 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc.

[0083] According to another typical embodiment of this application, a method for preparing an SEBS cross-linked composite anion exchange membrane is provided, comprising the following steps: providing functionalized SEBS, wherein the functionalized SEBS includes SEBS units and functional groups attached to the benzene rings contained in the side groups of the SEBS units, the functional groups being chloromethyl or activated acyl groups, the activated acyl groups containing reactive groups capable of nitrifying tertiary amine N; mixing the functionalized SEBS, a cross-linking agent, and a first solvent to perform a quaternization cross-linking reaction to obtain a cross-linked polymer solution, wherein the cross-linking agent is an alkylazabicycloene or an alkylpolyamine; disposing the cross-linked polymer solution on at least one side surface of a porous support layer and removing the solvent; and performing ion exchange on the composite membrane obtained after solvent removal in an alkaline solution to prepare any of the above-mentioned SEBS cross-linked composite anion exchange membranes.

[0084] The above preparation method involves a quaternization crosslinking reaction between functionalized SEBS and a crosslinking agent with a specific molecular structure to form a crosslinked polymer solution. This crosslinked polymer solution is then transformed into an active layer on the surface of a porous support layer. This active layer contains a three-dimensional network structure formed by the crosslinking agent and functionalized SEBS. This three-dimensional network structure is a stable three-dimensional covalent crosslinked network existing between polymer chains. This results in the active layer of the SEBS crosslinked composite anion exchange membrane not only possessing good electrical conductivity but also significantly reducing water absorption and swelling. This allows the membrane to maintain good dimensional stability even under high humidity conditions and helps to slow down the degradation of quaternary ammonium groups under strongly alkaline conditions. Furthermore, by combining the active layer containing the three-dimensional network structure with the porous support layer, the porous support layer provides strong mechanical support, enabling the composite membrane to withstand the physical stresses during operation in scenarios such as fuel cells or electrolyzers, further improving the integrity of the membrane structure and its long-term performance stability.

[0085] In some embodiments, the weight-average molecular weight of the functionalized SEBS is 50,000 to 1,000,000; optionally, the molar content of styrene in the functionalized SEBS is 20% to 60%.

[0086] The aforementioned functionalized SEBS can be either commercially available products or prepared in-house.

[0087] In some embodiments, the functional group includes chloromethyl, and chloromethylated SEBS is prepared by a method comprising the following steps: mixing SEBS, a chloromethylating agent, a first catalyst and a second solvent, performing a chloromethylation reaction, and obtaining chloromethylated SEBS by a first purification treatment.

[0088] Optionally, the chloromethylating agent includes any one or more of formaldehyde, paraformaldehyde, chloromethyl ether, dichloromethyl ether, chloromethylalkyl ether, and trimethylchlorosilane.

[0089] Optionally, the first catalyst is selected from any one or more of AlCl3, FeCl3, BF3, SnCl4, ZnCl2, HCl, H2SO4, H3PO4 and CH3COOH;

[0090] Optionally, the second solvent is selected from any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dichloromethane, toluene, and chloroform;

[0091] Optionally, the temperature of the chloromethylation reaction is 0℃-60℃, such as 0℃, 10℃, 20℃, 25℃, 30℃, 35℃, 40℃, 50℃, 60℃, etc. Further, the reaction time is 24 h-72 h, such as 24 h, 30 h, 36 h, 42 h, 48 h, 54 h, 60 h, 66 h, 72 h, etc.

[0092] In some embodiments, the functional group is an activated acyl group, and the acylated SEBS is prepared by a method comprising the following steps: mixing SEBS, an acylation reagent, a second catalyst and a third solvent, performing an acylation reaction, and obtaining the acylated SEBS by a second purification treatment.

[0093] In some embodiments, the acylation reagent includes any one or more of acyl halides, acid anhydrides, carboxylic acids, and amides, and the acylation reagent contains a reactive group capable of nitrifying a tertiary amine N.

[0094] In some embodiments, the second catalyst is selected from any one or more of AlCl3, FeCl3, BF3, SnCl4, ZnCl2, HCl, H2SO4, H3PO4 and CH3COOH;

[0095] In some embodiments, the third solvent is independently selected from any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dichloromethane, toluene, and chloroform;

[0096] In some embodiments, the temperature of the acylation reaction is 0℃-60℃, such as 0℃, 10℃, 20℃, 25℃, 30℃, 35℃, 40℃, 50℃, 60℃, etc. Further, the time of the acylation reaction is 24 h-72 h, such as 24 h, 30 h, 36 h, 42 h, 48 h, 54 h, 60 h, 66 h, 72 h, etc.

[0097] In some embodiments, the chloromethylation or acylation reaction described above is carried out in an inert atmosphere. For example, the gas providing the inert atmosphere includes, but is not limited to, any one or more of nitrogen, argon, helium, and krypton.

[0098] In some embodiments, the first purification process or the second purification process includes precipitation and washing processes; optionally, the detergent used in the precipitation and washing processes is selected from any one or more of water, ethanol, methanol, diethyl ether and ethyl acetate.

[0099] In some embodiments, the first solvent is selected from any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dichloromethane, toluene, and chloroform.

[0100] In some embodiments, the mass ratio of functionalized SEBS to crosslinking agent is 1:0.3-0.7, and the resulting three-dimensional covalent crosslinked network is beneficial for further improving the performance of the SEBS crosslinked composite anion exchange membrane. Non-limitingly, the mass ratio of functionalized SEBS to crosslinking agent can be 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, etc.

[0101] In some embodiments, the temperature of the quaternization crosslinking reaction is 20°C-80°C; non-limitingly, the temperature of the quaternization crosslinking reaction can be 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, etc.

[0102] In some embodiments, the quaternization crosslinking reaction time is 12 h-48 h; non-limitingly, the quaternization crosslinking reaction time can be 12 h, 18 h, 24 h, 30 h, 36 h, 42 h, 48 h, etc.

[0103] In some embodiments, the solid content of the crosslinked polymer solution is 5 wt%-30 wt%. Non-limitingly, the solid content of the crosslinked polymer solution is 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, etc.

[0104] In some embodiments, the alkali in the alkaline solution includes at least one of potassium hydroxide, sodium hydroxide, and calcium hydroxide. Optionally, the concentration of the alkali in the alkaline solution is 1 M to 6 M.

[0105] According to another typical embodiment of this application, the application of an SEBS cross-linked composite anion exchange membrane prepared by any of the above-described methods in the preparation of fuel cells or electrolysis devices is provided. By using the above-described SEBS cross-linked composite anion exchange membrane, fuel cells or electrolysis devices can achieve both superior performance and a longer service life.

[0106] In some embodiments, the fuel cell includes a membrane electrode assembly (MEA), which includes an anion exchange membrane, wherein the anion exchange membrane is the SEBS cross-linked composite anion exchange membrane described above.

[0107] In some embodiments, the electrolysis device includes a cathode, an anode, an anion exchange membrane, and an electrolytic cell injected with electrolyte. The cathode, anode, and anion exchange membrane are respectively disposed within the electrolytic cell, with the anion exchange membrane disposed between the cathode and the anode. The anion exchange membrane is the aforementioned SEBS cross-linked composite anion exchange membrane. Optionally, the electrolysis device is a water electrolysis hydrogen production device.

[0108] The following are specific examples.

[0109] Example 1

[0110] (1) Preparation of chloromethylated SEBS

[0111] 5g of SEBS (weight average molecular weight of about 20w, styrene molar content of 58%) was dissolved in 80mL of chloroform, and 3.8g of paraformaldehyde, 5.5mL of trimethylchlorosilane and 0.8mL of SnCl4 were added. The mixture was reacted at 30°C for 48 hours under a nitrogen atmosphere. The chloromethylated SEBS was purified by precipitation and washing with anhydrous ethanol.

[0112] (2) Preparation of cross-linked polymer solution

[0113] 5g of chloromethylated SEBS and 0.12g of crosslinking agent were mixed. Dissolve in 20 mL of toluene and react at 20 °C for 12 hours to form a cross-linked polymer solution;

[0114] (3) Preparation of composite anion exchange membrane

[0115] The crosslinked polymer solution was coated onto a 40 μm polyether ether ketone mesh (mesh size 80). The active layer and the support layer were bonded by heating to evaporate the solvent. The membrane was then immersed in a 1M sodium hydroxide solution for 24 h for ion exchange to obtain a composite anion exchange membrane with an active layer thickness of 60 μm.

[0116] Example 2

[0117] (1) Preparation of acylated SEBS

[0118] 5 g of SEBS (same as in Example 1) was dissolved in 150 mL of chloroform, and 4 mL of 6-bromohexanoyl chloride and 3 g of AlCl3 were added. The mixture was reacted at 40 °C for 24 hours under a nitrogen atmosphere. The acylated SEBS was purified by precipitation and washing with anhydrous methanol. Its NMR spectrum is shown below. Figure 4 As shown;

[0119] (2) Preparation of cross-linked polymer solution

[0120] 5g of chloromethylated SEBS was mixed with 0.14g of crosslinking agent. Dissolve in 20 mL of toluene and react at 25 °C for 18 hours to form a cross-linked polymer solution;

[0121] (3) Preparation of composite anion exchange membrane

[0122] The crosslinked polymer solution was coated onto a 40 μm thick polyetheretherketone mesh (60 mesh). The active layer was bonded to the support layer by heating to evaporate the solvent. The membrane was then immersed in a 1 M potassium hydroxide solution for 24 h for ion exchange to obtain a composite anion exchange membrane with an active layer thickness of 60 μm.

[0123] Example 3

[0124] The difference from Example 1 lies in step (2), the preparation of the crosslinked polymer solution, the detailed process of which is as follows:

[0125] 5g of chloromethylated SEBS and 0.12g of crosslinking agent were mixed. Dissolve in 20 mL and react at 40 °C for 56 hours to form a cross-linked polymer solution.

[0126] Example 4

[0127] The difference from Example 2 lies in step (2), the preparation of the crosslinked polymer solution, the detailed process of which is as follows:

[0128] 5g of acylated SEBS and 0.18g of crosslinking agent were mixed. Dissolve in 30 mL of toluene and react at 35 °C for 48 hours to form a cross-linked polymer solution.

[0129] Example 5

[0130] The difference from Example 1 is that in step (2) of preparing the crosslinking polymer solution, the crosslinking agent is replaced with 0.23g of... .

[0131] Example 6

[0132] The difference from Example 1 is that in step (2) of preparing the crosslinking polymer solution, the crosslinking agent is replaced with 0.18g of .

[0133] Comparative Example 1

[0134] (1) Preparation of acylated SEBS

[0135] 5g of SEBS (same as in Example 1) was dissolved in 150mL of chloroform, 3mL of 6-bromohexanoyl chloride and 2g of AlCl3 were added, and the mixture was reacted at 45°C for 36 hours under a nitrogen atmosphere. The acylated SEBS was obtained by precipitating and washing with anhydrous methanol.

[0136] (2) Preparation of cross-linked polymer solution

[0137] 5g of chloromethylated SEBS and 0.15g of N,N,N',N'-tetramethyl-1,6-hexanediamine were dissolved in 20mL of toluene and reacted at 20℃ for 20 hours to form a cross-linked polymer solution.

[0138] (3) Preparation of anion exchange membranes

[0139] A cross-linked polymer solution was coated onto a substrate, and the solvent was evaporated by heating to obtain a homogeneous anion exchange membrane with a thickness of 60 μm without reinforcement. The membrane was then immersed in a 1 M potassium hydroxide solution for 24 h for ion exchange to obtain the anion exchange membrane.

[0140] Comparative Example 2

[0141] (1) Preparation of acylated SEBS

[0142] 5g of SEBS (same as in Example 1) was dissolved in 150mL of chloroform, 3mL of 6-bromohexanoyl chloride and 2g of AlCl3 were added, and the mixture was reacted at 40°C for 24 hours under a nitrogen atmosphere. The acylated SEBS was obtained by precipitating and washing with anhydrous methanol.

[0143] (2) Preparation of composite anion exchange membrane

[0144] 5g of acylated SEBS was dissolved in 20mL of toluene to obtain a polymer membrane solution. The polymer solution was coated onto a 40μm polyetheretherketone mesh (same as in Example 1). The active layer and the support layer were bonded by evaporating the solvent by heating. The membrane was then immersed in a 30wt.% trimethylamine aqueous solution for 1 day and then immersed in a 1M potassium hydroxide solution for 24 hours for ion exchange to obtain a composite anion exchange membrane with a coating thickness of 60μm.

[0145] Comparative Example 3

[0146] (1) Preparation of acylated SEBS

[0147] 5g of SEBS (same as in Example 1) was dissolved in 150mL of chloroform, 2mL of 6-bromohexanoyl chloride and 2g of AlCl3 were added, and the mixture was reacted at 40°C for 24 hours under a nitrogen atmosphere. The acylated SEBS was obtained by precipitating and washing with anhydrous methanol.

[0148] (2) Preparation of cross-linked polymer solution

[0149] 5g of chloromethylated SEBS and 0.15g of N,N,N',N'-tetramethyl-1,6-hexanediamine were dissolved in 20mL of toluene and reacted at 20℃ for 12 hours to form a cross-linked polymer solution.

[0150] (3) Preparation of composite anion exchange membrane

[0151] The crosslinked polymer solution was coated onto a 40 μm polyether ether ketone (PEEK) mesh (same as in Example 1). The active layer and the support layer were bonded by heating to evaporate the solvent. The membrane was then immersed in a 1M potassium hydroxide solution for 24 hours for ion exchange to obtain a composite anion exchange membrane with a coating thickness of 60 μm.

[0152] The performance of the anion exchange membranes prepared in the above embodiments and comparative examples was tested using the following methods:

[0153] Impedance testing: The impedance of the anion exchange membrane was measured by p-EIS method using an electrochemical workstation (gamry) at room temperature (25℃).

[0154] Conductivity: The resistance at room temperature (25℃) was measured using the p-EIS impedance method, and the conductivity of the membrane was calculated using the formula σ=L / RA (where R is the impedance of the membrane, L is the thickness of the membrane, and A is the effective area of ​​the membrane).

[0155] Tensile strength and elongation at break: The tensile strength and elongation at break of the wet film were tested using a tensile testing machine (LABRD-V2.9). Figure 1 A comparison diagram of the mechanical strength of the anion exchange membranes in Example 2 and Comparative Example 1;

[0156] Alkali absorption rate: A membrane of a certain size is immersed in 1M KOH and soaked at room temperature for 24 hours. Then, the membrane is taken out and the liquid on the surface is wiped off with absorbent paper and its weight is weighed. The membrane sample is then wrapped regularly with absorbent paper and placed in a vacuum dryer at 60℃ for 24 hours. Its dry weight is then weighed. The alkali absorption rate is obtained by using the formula W=(Wwet-Wdry) / Wdry ×100% (Wwet represents the mass of the wet membrane and Wdry represents the mass of the dry membrane).

[0157] Swelling rate: A membrane of a certain size was immersed in 1M KOH and soaked at room temperature for 24 hours. The membrane was then removed and the liquid on the surface was wiped off with absorbent paper before weighing. The membrane sample was then wrapped regularly with absorbent paper and vacuum dried at 60℃ for 24 hours. The dry weight was then weighed. The swelling rate was obtained using the formula S=(Lwet-Ldry) / Ldry ×100% (where Lwet represents the length of the wet membrane and Ldry represents the length of the dry membrane).

[0158] The test results are shown in Table 1.

[0159] Table 1

[0160]

[0161] The anion exchange membranes prepared in the above examples and comparative examples were assembled into an electrolysis device. The electrolyte in the electrolysis device was a 1 mol / L KOH solution. The anode was cyclic with alkaline solution on one side. The cathode was made of 2.3 mm compressed nickel foam, 0.6 mm raw carbon cloth and 0.3 mm catalyst carbon cloth. The anode was made of 2.5 mm compressed catalyst nickel foam.

[0162] The current density of the above electrolysis device was tested at 60℃ and 1.7V, and the test results are shown in Table 2. Figure 2 The polarization curves of water electrolysis at 60°C for Example 2 and Comparative Example 1 are shown.

[0163] The above electrolysis device was tested at 60℃ and 10000 A / m. 2 Stability under, Figure 3 The data are the electrolytic stability data for Example 2.

[0164] Table 2

[0165]

[0166] The performance tests of the above examples and comparative examples show that the SEBS cross-linked polymer solution prepared by cross-linking SEBS and then coated onto a porous support layer, produces a SEBS cross-linked composite anion exchange membrane that exhibits excellent alkali stability, high ionic conductivity, and excellent mechanical strength. The anion exchange membrane prepared in the examples effectively inhibits intramembrane swelling, improves mechanical properties, promotes the formation of intramembrane microphase separation, and enhances ionic conductivity. Furthermore, the electrolysis device assembled with the anion exchange membrane prepared in the examples can operate at 60°C and 10000 A / m... 2 It can run stably for more than 150 hours.

[0167] Comparative Examples 1 and 3 show that using a porous support layer can effectively suppress membrane swelling and improve the mechanical properties of anion exchange membranes.

[0168] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0169] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A SEBS cross-linked composite anion exchange membrane, characterized in that, Includes an active layer and a porous support layer; The active layer includes a crosslinked polymer, which includes a linear SEBS unit and a crosslinking unit. The linear SEBS unit includes a linear carbon backbone and an S side group attached to the linear carbon backbone. The S side group includes a benzene ring, and the benzene ring is attached with a methylene group or an acyl group. The crosslinking unit comprises at least three quaternary ammonium N-onium ions indirectly covalently linked to the benzene ring in the S-side group, wherein two of the positively charged N-ions in the at least two quaternary ammonium N-onium ions are connected via [-CH2-(A)]. X -CH2-] U Or -(CH2) Y -CH2- is connected; wherein, each A is independently selected from a carbon atom, an oxygen atom, or a benzene ring, and (A) X In this case, the oxygen atom is not adjacent to any other oxygen atom, U is an integer selected from 1 to 10, X is an integer selected from 0 to 5, and Y is an integer selected from 1 to 10. In this context, the positively charged N in the quaternary ammonium-type N-onium ion participates in the formation of two diazabicyclic rings, or... The positively charged N in the quaternary ammonium Nionium ion is connected to R1, R2, and R3, wherein R1 and R2 are each independently C. 1-3 Alkyl group, R3 is a group containing a quaternary ammonium salt.

2. The SEBS cross-linked composite anion exchange membrane according to claim 1, characterized in that, The crosslinked polymer satisfies at least one of the following characteristics: The diazabicyclo ring is a 1,4-diazabicyclo[2.2.2]octane ring; The positively charged N in the quaternary ammonium Nionium ion combines with the halide anion to form an ion pair; The number of methylene groups in the S side group is 1 to 20.

3. The SEBS cross-linked composite anion exchange membrane according to claim 2, characterized in that, The crosslinking unit includes any one or more of the following: alkyl azabicyclic groups having the structure shown in Formula I and alkyl polyamine groups having the structure shown in Formula II: Formula I Formula II In the formula, * represents the site connected to the S side base, X is any integer selected from 0-5, and U is any integer selected from 1-10; Y1, Y2, and Y3 are each an independent integer from 1 to 10.

4. The SEBS cross-linked composite anion exchange membrane according to any one of claims 1 to 3, characterized in that, The active layer includes at least one of the following features: The mass ratio of the SEBS unit to the crosslinking unit is 1:(0.3-0.7). The thickness of the active layer is 40 μm-100 μm.

5. The SEBS cross-linked composite anion exchange membrane according to any one of claims 1 to 3, characterized in that, The porous support layer includes at least one of the following features: The porous support layer is made of any one or more of polyetheretherketone, polyphenylene sulfide, polyethylene, polyethylene terephthalate, polypropylene, or polytetrafluoroethylene. The mesh size of the porous support layer is 10-200; The thickness of the porous support layer is 20 μm-80 μm, and optionally, the thickness of the porous support layer is 30 μm-50 μm.

6. A method for preparing a SEBS cross-linked composite anion exchange membrane, characterized in that, Includes the following steps: A functionalized SEBS is provided; wherein the functionalized SEBS comprises an SEBS unit and a functional group attached to a benzene ring contained in a side group of the SEBS unit, the functional group being a chloromethyl group or an activated acyl group, the activated acyl group containing a reactive group capable of nitrifying a tertiary amine N; The functionalized SEBS, crosslinking agent, and first solvent are mixed and subjected to a quaternization crosslinking reaction to obtain a crosslinked polymer solution; wherein the crosslinking agent is an alkylazabicyclohexane or an alkylpolyamine. The crosslinked polymer solution is disposed on at least one surface of the porous support layer, and the solvent is removed; The composite membrane obtained after removing the solvent is subjected to ion exchange in an alkaline solution to prepare the SEBS cross-linked composite anion exchange membrane according to any one of claims 1 to 5.

7. The method for preparing the SEBS cross-linked composite anion exchange membrane according to claim 6, characterized in that, The steps of providing the functionalized SEBS include at least one of the following features: The functional group is chloromethyl, and the functionalized SEBS is prepared by a method including the following steps: mixing SEBS, chloromethylating agent, first catalyst and second solvent, carrying out chloromethylation reaction, and obtaining chloromethylated SEBS after first purification treatment; The functional group is an activated acyl group, and the functionalized SEBS is prepared by a method including the following steps: mixing SEBS, acylation reagent, second catalyst and third solvent, carrying out acylation reaction, and obtaining acylated SEBS by second purification treatment.

8. The method for preparing the SEBS cross-linked composite anion exchange membrane according to claim 7, characterized in that, The steps of providing the functionalized SEBS include at least one of the following features: The chloromethylating agent includes any one or more of formaldehyde, trioxymethylene, paraoxymethylene, chloromethyl ether, dichloromethyl ether, chloromethylalkyl ether, and trimethylchlorosilane; The acylation reagent includes any one or more of acyl halides, acid anhydrides, carboxylic acids, and amides, and the acylation reagent contains a reactive group capable of nitrifying tertiary amine N. The first catalyst and the second catalyst are each independently selected from any one or more of AlCl3, FeCl3, BF3, SnCl4, ZnCl2, HCl, H2SO4, H3PO4 and CH3COOH; The second solvent and the third solvent are each independently selected from any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dichloromethane, toluene, and chloroform; The chloromethylation reaction was carried out at a temperature of 0℃-60℃ for 24 h-72 h. The acylation reaction was carried out at a temperature of 0℃-60℃ for a time of 24 h-72 h. The first purification process or the second purification process includes precipitation and washing processes; optionally, the detergent used in the precipitation and washing processes is selected from any one or more of water, ethanol, methanol, diethyl ether and ethyl acetate.

9. The method for preparing the SEBS cross-linked composite anion exchange membrane according to any one of claims 6 to 8, characterized in that, Includes at least one of the following features: The first solvent is selected from any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dichloromethane, toluene, and chloroform; The mass ratio of the functionalized SEBS to the crosslinking agent is 1:(0.3-0.7). The temperature for the quaternization crosslinking reaction is 20℃-80℃; The quaternization crosslinking reaction takes 12 h to 48 h; The solid content of the crosslinked polymer solution is 5 wt%-30 wt%. The alkali in the alkaline solution includes at least one of potassium hydroxide, sodium hydroxide, and calcium hydroxide.

10. The application of the SEBS cross-linked composite anion exchange membrane prepared by the method of any one of claims 1 to 5 or the SEBS cross-linked composite anion exchange membrane prepared by any one of claims 6 to 9 in the preparation of fuel cells or electrolysis devices.

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