Crosslinking of aromatic polymers for anion exchange membranes
Through the crosslinking polymer network method, the problem of anion exchange membrane being easy to degrade and soften when hydrated under high alkaline conditions is solved, achieving higher stability and durability while maintaining the ion exchange capacity unchanged.
Patent Information
- Application Number
- CN202510451800.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2018-04-24
- Filing Date
- 2019-04-24
- Publication Date
- 2025-07-25
AI Technical Summary
The existing anion exchange membranes are prone to degradation under high alkaline conditions, and when hydrated, the polymer softens and swells due to its strong interaction with water, affecting its stability and durability.
Using a crosslinked polymer network, a crosslinked polymer network is formed by functionalizing the phenyl group of poly(styrene-b-ethylene-r-butene-b-styrene) triblock copolymer (SEBS) and crosslinking with a diamine linker to form a crosslinked polymer network, increasing the linker concentration to improve the stability of the film.
It improves the stability and durability of the ion exchange membrane under hydration conditions, while reducing water absorption and hardly affects the ion exchange capacity.
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Figure CN120365574A_ABST
Abstract
Description
[0001] This application is a divisional application of Chinese Patent Application (PCT / US2019 / 028925) with an application date of April 24, 2019 and an invention title of "Crosslinking of Aromatic Polymers for Anion Exchange Membranes".
[0002] Cross - reference to related applications
[0003] This application claims the benefit of U.S. Provisional Application No. 62 / 661,705, filed on April 24, 2018, which is incorporated herein by reference in its entirety as if fully set forth herein.
[0004] Statement regarding federally - sponsored research
[0005] This invention was made with government support under Contract No. DE - AR0000769 awarded by the Department of Energy. The government has certain rights in this invention. Background of the invention
[0006] Alkaline exchange membranes (AEMs), also known as anion exchange membranes, permit the transport of anions such as OH - , Cl - , Br - etc. from the cathode to the anode in an electrochemical reaction. AEMs are components of AEM fuel cells in which hydrogen and oxygen are used to generate electricity and water by - products. AEMs are also used in water electrolysis, in which water is decomposed into hydrogen and oxygen with the aid of electricity, which is the cleanest and most desirable hydrogen - production process. In AEM fuel cells and water electrolysis, hydroxide ions (OH-) are transported through the membrane with the help of water molecules. Other fields in which AEMs are used include batteries, sensors, and actuators (the plastic membrane swings reversibly due to ion migration).
[0007] In recent years, several research groups have developed new AEM materials. However, these materials tend to degrade unfavorably at high alkalinity. Currently, most anion AEMs are prepared from polymers containing quaternary ammonium groups along the side chains. Unfortunately, these ionic side groups interact strongly with water, which acts as a plasticizer and causes softening and swelling of the polymer upon hydration. Summary of the invention
[0009] Some embodiments of the present disclosure relate to ion exchange membrane materials composed of crosslinked polymer networks, the crosslinked polymer networks including a first poly(styrene-b-ethylene-r-butylene-b-styrene) triblock copolymer (SEBS), wherein at least one phenyl group of the first SEBS is functionalized with a first alkyl group, and the carbon at the benzylic position of the first alkyl group is saturated with at least two additional alkyl groups; a second poly(styrene-b-ethylene-r-butylene-b-styrene) triblock copolymer (SEBS), wherein at least one phenyl group of the second SEBS is functionalized with a second alkyl group, and the carbon at the benzylic position of the second alkyl group is saturated with at least two additional alkyl groups; and a diamine linker bonded to the first alkyl group and the second alkyl group. In some embodiments, at least one phenyl group of the first SEBS is functionalized with an uncrosslinked alkyl group, the carbon at the benzylic position of the uncrosslinked alkyl group is saturated with at least two additional alkyl groups, and the uncrosslinked alkyl group includes a quaternary ammonium group. In some embodiments, at least one phenyl group of the second SEBS is functionalized with an uncrosslinked alkyl group, the carbon at the benzylic position of the uncrosslinked alkyl group is saturated with at least two additional alkyl groups, and the uncrosslinked alkyl group includes a quaternary ammonium group. In some embodiments, the concentration of the diamine linker in the crosslinked polymer network is greater than about 5 mol%. In some embodiments, the concentration of the diamine linker in the crosslinked polymer network is greater than about 30 mol%. In some embodiments, the concentration of the diamine linker in the crosslinked polymer network is about 50 mol%. In some embodiments, the diamine linker is N,N,N,N′-tetramethyl-1,6-hexanediamine.
[0010] Some embodiments of the present disclosure relate to methods of preparing ion exchange membranes, the methods including: functionalizing an aromatic block copolymer with one or more alkyl halide groups, the carbon at the benzylic position of the one or more alkyl halide groups being saturated with at least two additional alkyl groups; mixing the functionalized aromatic block copolymer with a diamine to replace one or more halogen groups with quaternary ammonium groups; and crosslinking the functionalized aromatic block copolymer with another functionalized aromatic block copolymer through the diamine to produce a crosslinked polymer. In some embodiments, the linker is a diamine linker, a polyol, a polyaromatic compound, an olefin dimer, a dithiol, or a combination thereof. In some embodiments, the diamine has two tertiary amine groups. In some embodiments, the method includes adding a trialkylamine to the crosslinked polymer to convert unreacted alkyl halide groups to quaternary ammonium groups. In some embodiments, the aromatic block copolymer is a biphenyl polymer. Brief Description of the Drawings
[0012] The accompanying drawings illustrate embodiments of the disclosed subject matter for purposes of illustration. It should be understood, however, that the present application is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:
[0013] Figure 1 is a schematic diagram of an ion exchange material for manufacturing an ion exchange membrane according to some embodiments of the present disclosure;
[0014] Figure 2 is a diagram of a method for manufacturing an ion exchange membrane according to some embodiments of the present disclosure;
[0015] Figure 3 is a table showing that the water absorption rate in the ion exchange material decreases with the increase of the crosslinking agent according to some embodiments of the present disclosure;
[0016] Figure 4 is a diagram of a method for manufacturing an ion exchange membrane according to some embodiments of the present disclosure;
[0017] Figure 5 is a diagram of a method for manufacturing an ion exchange membrane according to some embodiments of the present disclosure;
[0018] Figure 6 is a diagram of a method for manufacturing an ion exchange membrane according to some embodiments of the present disclosure;
[0019] Figure 7 is a diagram of a method for manufacturing an ion exchange membrane according to some embodiments of the present disclosure;
[0020] Figure 8 is a diagram of a method for manufacturing an ion exchange membrane according to some embodiments of the present disclosure;
[0021] Figure 9 is a diagram of a method for manufacturing an ion exchange membrane according to some embodiments of the present disclosure. Detailed Description
[0023] Now referring to Figure 1 , some aspects of the disclosed subject matter include an ion exchange material 100. In some embodiments, the ion exchange material is suitable for use as an ion exchange membrane for, for example, fuel cells, water hydrolysis systems, electrochemical hydrogen compressors, batteries, sensors, actuators, and the like. In some embodiments, the ion exchange membrane is an anion exchange membrane.
[0024] In some embodiments, the ion exchange material 100 includes a crosslinked polymer network 102. In some embodiments, the crosslinked network 102 includes one or more polymer chains 104 and one or more linkers 106 that connect the one or more polymer chains 104. In some embodiments, the polymer chains 104 are polyaromatic polymers, copolymers, block copolymers, or combinations thereof. In some embodiments, the polymer chains 104 are functionalized with one or more functional groups.
[0025] In some embodiments, one or more of the polymer chains 104 are poly(styrene-b-ethylene-r-butylene-b-styrene) triblock copolymers (SEBS). In some embodiments, at least one phenyl group of the polymer chain 104 such as SEBS is functionalized with at least one alkyl group. In some embodiments, the carbon at the benzylic position of the at least one alkyl group is saturated with at least two additional carbons, alkyl groups, etc. In some embodiments, the at least one alkyl group is a haloalkyl group before being crosslinked to another polymer chain 104 via one or more linkers 106, which will be discussed in more detail below. In some embodiments, the linker 106 crosslinks the polymer chains 104 through the bonding between alkyl functional groups on the polymer chains. In some embodiments, the linker 106 is a diamine. In some embodiments, the diamine includes at least two tertiary amine groups with an alkyl group therebetween. In some embodiments, the linker is N,N,N′,N′-tetramethyl-1,6-hexanediamine. In some embodiments, at least one phenyl group of the crosslinked network 102 is functionalized with an uncrosslinked alkyl group, and the carbon at the benzylic position of the uncrosslinked alkyl group is saturated with at least two additional alkyl groups, and the uncrosslinked alkyl group includes a quaternary ammonium group.
[0026] In some embodiments, the concentration of the linker in the crosslinked polymer network is greater than about 5 mol% of the alkyl functional groups. In some embodiments, the concentration of the linker in the crosslinked polymer network is greater than about 30 mol% of the alkyl functional groups. In some embodiments, the concentration of the linker in the crosslinked polymer network is about 50 mol% of the alkyl functional groups. In some embodiments, the concentration of the linker in the crosslinked polymer network is greater than about 50 mol% of the alkyl functional groups.
[0027] By way of example, and still referring to Figure 1, the crosslinked polymer network 102 includes first SEBS chains 104, where at least one phenyl group of the first SEBS is functionalized with a first alkyl group, and the carbon at the benzylic position of the first alkyl group is saturated with at least two additional alkyl groups. The first SEBS chains 104 are crosslinked with second SEBS chains 104', where at least one phenyl group of the second SEBS is functionalized with a second alkyl group, and the carbon at the benzylic position of the second alkyl group is saturated with at least two additional alkyl groups. A diamine linker 106 is bonded to the first and second alkyl groups, resulting in the structure of Formula I:
[0028]
[0029] where R1 includes H or CH3 and R2 includes CH3.
[0030] Now referring to Figure 2 , some embodiments of the present disclosure relate to methods for manufacturing ion exchange membranes, such as reaction pathways. At 202, an aromatic block copolymer such as SEBS is functionalized with one or more alkyl halide groups. In some embodiments, the carbon at the benzylic position of the one or more alkyl halide groups is saturated with at least two additional alkyl groups. At 204, the functionalized aromatic block copolymer is mixed with a linker to replace one or more halogen groups with quaternary ammonium groups, and the functionalized aromatic block copolymer is crosslinked with another functionalized aromatic block copolymer through the linker to form a crosslinked polymer network. At 206, the unreacted alkyl halide groups are converted to quaternary ammonium groups by adding a trialkylamine. Referring to Figure 3 , the higher the concentration (mol%) of the linker, the lower the water absorption of the network and the membrane.
[0031] Referring again to Figure 1, in some embodiments, one or more polymer chains 104 are biphenyl block polymers. In some embodiments, the biphenyl block polymers are functionalized with one or more alkyl groups. In some embodiments, the linker 106 crosslinks the biphenyl block polymers by bonding between alkyl functional groups on the chains. In some embodiments, the linker is a diamine linker, a polyol, a polyaromatic compound, an olefin dimer, a dithiol, or a combination thereof, as will be discussed in more detail below. In some embodiments, the concentration of the linker in the crosslinked biphenyl block polymer network is greater than about 5 mol% of the alkyl functional groups. In some embodiments, the concentration of the linker in the crosslinked biphenyl block polymer network is greater than about 30 mol% of the alkyl functional groups. In some embodiments, the concentration of the linker in the crosslinked biphenyl block polymer network is about 50 mol% of the alkyl functional groups. In some embodiments, the concentration of the linker in the crosslinked biphenyl block polymer network is greater than about 50 mol% of the alkyl functional groups. In some embodiments, at least one alkyl functional group is uncrosslinked and includes a quaternary ammonium group.
[0032] Now refer to Figure 4 , in some embodiments, one or more biphenyl block polymers are functionalized with alkyl halide groups. In some embodiments, the one or more biphenyl block polymers are mixed with a linker such as a diamine, for example by casting, and a substantially simultaneous quaternization and crosslinking reaction is carried out and crosslinked to other biphenyl block polymers. In some embodiments, the unreacted alkyl halide groups are converted to quaternary ammonium groups by adding a trialkylamine.
[0033] Now refer to Figure 5 , in some embodiments, one or more biphenyl block polymers are functionalized with alkyl halide groups. In some embodiments, a mixture of a trialkylamine and a dialkylamine is added to the biphenyl block polymers to convert the halogen in the alkyl halide groups to a mixture of quaternary ammonium and tertiary amine groups. In some embodiments, the one or more biphenyl block polymers are mixed with a linker such as a diamine, for example by casting, and a substantially simultaneous quaternization and crosslinking reaction is carried out on the tertiary amine groups.
[0034] Now refer to Figure 6 , in some embodiments, one or more biphenyl block polymers are functionalized with alkyl halide groups. In some embodiments, the one or more biphenyl block polymers are mixed with a polyol such as a diol or a triol, for example by casting, and an etherification reaction is carried out and crosslinked to other biphenyl block polymers. In some embodiments, the unreacted alkyl halide groups are converted to quaternary ammonium groups by adding a trialkylamine.
[0035] Now refer to Figure 7, in some embodiments, one or more biphenyl block polymers are functionalized with alkyl halide groups. In some embodiments, the one or more biphenyl block polymers are reacted with a base to convert at least some of the halogens to vinyl groups. In some embodiments, the vinyl groups undergo a crosslinking reaction with a polyaromatic compound via acid-catalyzed Friedel-Crafts alkylation, such that the aromatic rings act as crosslinking agents between polymers in the crosslinked polymer network. In some embodiments, the polyaromatic compound includes a biphenyl compound, a biphenyl ether compound, a triptycene compound, a fluorene or fluorene derivative compound, etc., or a combination thereof. In some embodiments, the unreacted alkyl halide groups are converted to quaternary ammonium groups by adding a trialkylamine.
[0036] Now refer to Figure 8 , in some embodiments, one or more biphenyl block polymers are functionalized with alkyl halide groups. In some embodiments, the one or more biphenyl block polymers are reacted with a base to convert at least some of the halogens to vinyl groups. In some embodiments, the one or more biphenyl block polymers are then irradiated with ultraviolet light, resulting in the dimerization of the vinyl groups into cyclobutane rings, which act as crosslinking agents between polymers in the crosslinked polymer network. In some embodiments, the unreacted alkyl halide groups are converted to quaternary ammonium groups by adding a trialkylamine.
[0037] Now refer to Figure 9 , in some embodiments, one or more biphenyl block polymers are functionalized with alkyl halide groups. In some embodiments, the one or more biphenyl block polymers are reacted with a base to convert at least some of the halogens to vinyl groups. In some embodiments, the vinyl groups undergo a crosslinking reaction via UV radiation and the addition of a dithiol. The thiol-ene reaction crosslinks the polymers in the crosslinked polymer network, where the dithiol acts as a crosslinking agent. In some embodiments, the dithiol is an alkyldithiol, such as SH-(CH2) n )-SH. In some embodiments, the unreacted alkyl halide groups are converted to quaternary ammonium groups by adding a trialkylamine.
[0038] The method of the present disclosure is advantageous as a general method for preparing ion exchange membranes and ionomer binders from any styrene copolymer functionalized with an alkyl halide group. The reaction conditions are straightforward, and since quaternization and crosslinking occur substantially simultaneously, the reaction itself can be carried out in relatively few steps. Additionally, simply increasing the concentration of the crosslinker in the reactions described herein produces membranes with reduced water absorption, leading to the expectation of increased stability and greater durability under hydrated conditions. Advantageously, this reduction in water absorption hardly alters the ion exchange capacity. The crosslinked polymer network according to an embodiment of the present disclosure can be used in applications such as batteries, anion exchange membrane fuel cells, anion exchange membrane electrolysis, ionomers for fuel cells and electrolysis, membranes and ionomers for other electrochemical energy conversion devices, water purification, gas separation (especially CO2 from coal-fired power plants), and the like.
[0039] The present disclosure provides the following embodiments:
[0040] Embodiment 1. An ion exchange membrane material comprising a crosslinked polymer network, the crosslinked polymer network comprising:
[0041] A first poly(styrene-b-ethylene-r-butylene-b-styrene) triblock copolymer (SEBS), wherein at least one phenyl group of the first SEBS is functionalized with a first alkyl group, and the carbon at the benzylic position of the first alkyl group is saturated with at least two additional alkyl groups;
[0042] A second poly(styrene-b-ethylene-r-butylene-b-styrene) triblock copolymer (SEBS), wherein at least one phenyl group of the second SEBS is functionalized with a second alkyl group, and the carbon at the benzylic position of the second alkyl group is saturated with at least two additional alkyl groups; and
[0043] A diamine linker bonded to the first alkyl group and the second alkyl group.
[0044] Embodiment 2. The material of Embodiment 1, wherein at least one phenyl group of the first SEBS is functionalized with an uncrosslinked alkyl group, the carbon at the benzylic position of the uncrosslinked alkyl group is saturated with at least two additional alkyl groups, and the uncrosslinked alkyl group comprises a quaternary ammonium group.
[0045] Embodiment 3. The material of Embodiment 1, wherein at least one phenyl group of the second SEBS is functionalized with an uncrosslinked alkyl group, the carbon at the benzylic position of the uncrosslinked alkyl group is saturated with at least two additional alkyl groups, and the uncrosslinked alkyl group comprises a quaternary ammonium group.
[0046] Embodiment 4. The material of Embodiment 1, wherein the concentration of the diamine linker in the crosslinked polymer network is greater than about 5 mol%.
[0047] Embodiment 5. The material according to Embodiment 4, wherein the concentration of the diamine linker in the crosslinked polymer network is greater than about 30 mol%.
[0048] Embodiment 6. The material according to Embodiment 5, wherein the concentration of the diamine linker in the crosslinked polymer network is about 50 mol%.
[0049] Embodiment 7. The material according to Embodiment 1, wherein the diamine linker is N,N,N,N'-tetramethyl-1,6-hexanediamine.
[0050] Embodiment 8. The material according to Embodiment 1, wherein the crosslinked polymer comprises a structure according to Formula I:
[0051]
[0052] wherein R1 comprises H or CH3, and R2 comprises CH3.
[0053] Embodiment 9. A method for preparing an ion exchange membrane, the method comprising:
[0054] Functionalizing an aromatic block copolymer with one or more alkyl halide groups, wherein the carbon at the benzylic position of the one or more alkyl halide groups is saturated with at least two additional alkyl groups;
[0055] Mixing the functionalized aromatic block copolymer with a diamine to replace one or more halogen groups with quaternary ammonium groups; and
[0056] Crosslinking the functionalized aromatic block copolymer with another functionalized aromatic block copolymer through the diamine to produce a crosslinked polymer.
[0057] Embodiment 10. The method according to Embodiment 9, further comprising adding a trialkylamine to the crosslinked polymer to convert unreacted alkyl halide groups into quaternary ammonium groups.
[0058] Embodiment 11. The method according to Embodiment 10, wherein the concentration of the diamine linker in the crosslinked polymer is greater than about 5 mol%.
[0059] Embodiment 12. The method according to Embodiment 11, wherein the concentration of the diamine linker in the crosslinked polymer is greater than about 50 mol%.
[0060] Embodiment 13. The method according to Embodiment 9, wherein the diamine linker comprises two tertiary amine groups.
[0061] Embodiment 14. The method according to Embodiment 13, wherein the diamine linker is N,N,N,N'-tetramethyl-1,6-hexanediamine.
[0062] Embodiment 15. The method according to Embodiment 9, wherein the ion exchange membrane comprises a structure according to Formula I:
[0063]
[0064] wherein R1 comprises H or CH3, and R2 comprises CH3.
[0065] Embodiment 16. A method for preparing an ion exchange membrane, the method comprising:
[0066] functionalizing an aromatic block copolymer with one or more alkyl halide groups;
[0067] crosslinking the functionalized aromatic block copolymer with another functionalized aromatic block copolymer at the one or more alkyl halide groups to produce a crosslinked polymer through a linker; and
[0068] treating the crosslinked polymer with a trialkylamine to convert the uncrosslinked alkyl halide groups into ammonium groups.
[0069] Embodiment 17. The method according to Embodiment 16, wherein the concentration of the linker in the crosslinked polymer is greater than about 5 mol%.
[0070] Embodiment 18. The method according to Embodiment 17, wherein the concentration of the linker in the crosslinked polymer is about 50 mol%.
[0071] Embodiment 19. The method according to Embodiment 16, wherein the aromatic block copolymer is a biphenyl polymer.
[0072] Embodiment 20. The method according to Embodiment 16, wherein the linker is a diamine linker, a polyol, a polyaromatic compound, an olefin dimer, a dithiol, or a combination thereof.
[0073] Although the disclosed subject matter has been described and illustrated in connection with its embodiments, those skilled in the art will understand that the features of the disclosed embodiments can be combined, rearranged, etc. to produce additional embodiments within the scope of the present invention, and various other changes, omissions, and additions can be made thereto without departing from the spirit and scope of the present invention.
Claims
1. An ion exchange membrane material, which comprises a crosslinked polymer network, and the crosslinked polymer network includes: A first poly(styrene-b-ethylene-r-butylene-b-styrene) triblock copolymer (SEBS), wherein at least one phenyl group of the first SEBS is functionalized with a first alkyl group, and the carbon at the benzylic position of the first alkyl group is saturated with at least two additional alkyl groups; A second poly(styrene-b-ethylene-r-butylene-b-styrene) triblock copolymer (SEBS), wherein at least one phenyl group of the second SEBS is functionalized with a second alkyl group, and the carbon at the benzylic position of the second alkyl group is saturated with at least two additional alkyl groups; and A diamine linker bonded to the first alkyl group and the second alkyl group.
2. The material according to claim 1, which has at least one of the following characteristics: - At least one phenyl group of the first SEBS is functionalized with an uncrosslinked alkyl group, the carbon at the benzylic position of the uncrosslinked alkyl group is saturated with at least two additional alkyl groups, and the uncrosslinked alkyl group includes a quaternary ammonium group; - At least one phenyl group of the second SEBS is functionalized with an uncrosslinked alkyl group, the carbon at the benzylic position of the uncrosslinked alkyl group is saturated with at least two additional alkyl groups, and the uncrosslinked alkyl group includes a quaternary ammonium group; - The concentration of the diamine linker in the crosslinked polymer network is greater than about 5 mol%, preferably greater than about 30 mol%, and more preferably about 50 mol%; and - The diamine linker is N,N,N,N'-tetramethyl-1,6-hexanediamine.
3. The material according to claim 1, wherein the crosslinked polymer includes a structure according to Formula I: wherein R1 includes H or CH3, and R2 includes CH3.
4. A method for preparing an ion exchange membrane, the method comprising: Functionalizing an aromatic block copolymer with one or more alkyl halide groups, and the carbon at the benzylic position of the one or more alkyl halide groups is saturated with at least two additional alkyl groups; Mixing the functionalized aromatic block copolymer with a diamine to replace one or more halogen groups with quaternary ammonium groups; and Crosslinking the functionalized aromatic block copolymer with another functionalized aromatic block copolymer through the diamine to produce a crosslinked polymer.
5. The method according to claim 4, which further comprises adding a trialkylamine to the crosslinked polymer to convert unreacted alkyl halide groups into quaternary ammonium groups.
6. The method according to claim 5, wherein the concentration of the diamine linker in the crosslinked polymer is greater than about 5 mol%, preferably greater than about 30 mol%, and more preferably about 50 mol%.
7. The method according to claim 4, wherein the diamine linker includes two tertiary amine groups, and preferably the diamine linker is N,N,N,N'-tetramethyl-1,6-hexanediamine.
8. The method according to claim 4, wherein the ion exchange membrane includes a structure according to Formula I: wherein R1 includes H or CH3, and R2 includes CH3.
9. A method for preparing an ion exchange membrane, the method comprising: Functionalizing an aromatic block copolymer with one or more alkyl halide groups; Crosslink the functionalized aromatic block copolymer with another functionalized aromatic block copolymer at the one or more alkyl halide groups to produce a crosslinked polymer via a linker; and Treat the crosslinked polymer with a trialkylamine to convert the uncrosslinked alkyl halide groups to ammonium groups.
10. The method according to claim 9, characterized by at least one of the following features: - The concentration of the linker in the crosslinked polymer is greater than about 5 mol%, preferably about 50 mol%; - The aromatic block copolymer is a biphenyl polymer; and - The linker is a diamine linker, a polyol, a polyaromatic compound, an olefin dimer, a dithiol, or a combination thereof.