Method of aminating polymer membrane to make anion exchange membrane

Abstract

The present technology relates to an improved method for manufacturing an anion exchange membrane. The method uses trimethylamine gas to aminate a polymer film. The process involves placing a polymer membrane or roll having a thin spacer in a pressure vessel, removing air by applying a vacuum, and then filling the vessel with a trimethylamine gas at a pressure of about 1 bar and a temperature of about 30 DEG C. After amination, residual trimethylamine is removed by vacuum, optionally by heat treatment. This gas-based process eliminates film swelling and wrinkling problems associated with aqueous trimethylamine solutions, increases diffusion rates, reduces the production of waste, and allows for a more efficient and scalable production process, including the ability to aminate the entire polymer film roll. The resulting membranes maintain their structural integrity and are more suitable for assembly into electrochemical device stacks.

Description

Technical Field

[0001] This technology relates to a method for manufacturing anion exchange membranes, and more specifically, to a method for amination of polymer membranes to produce anion exchange membranes for use in electrochemical devices. Background Technology

[0002] This section provides background information in connection with this disclosure, which is not necessarily prior art.

[0003] Anion exchange membranes (AEMs) have become promising components for various electrochemical devices, including fuel cells, electrolyzers, and chemical separation systems. These membranes offer potential advantages over proton exchange membranes (PEMs) in terms of cost and performance.

[0004] Conventionally, the production of AEM involves a multi-step process, in which a prepolymer containing alkyl halide groups is first synthesized, followed by the formation of a membrane. The membrane is then subjected to a quaternization step, converting the alkyl halide groups into quaternary ammonium cations responsible for anion conduction.

[0005] A common method for quaternization involves immersing the prepolymer membrane in an aqueous trimethylamine solution. Examples of prior art involving aqueous solution methods are described in International Publication No. WO 2022 / 026794A1, filed July 30, 2021, entitled “Polycyclic Epoxy Polymers and Anion Exchange Membranes Derived Therefrom”. This document outlines a process for quaternization by immersing the membrane in a 50% by weight aqueous trimethylamine solution for 48 hours at room temperature.

[0006] While effective, this aqueous solution method presents several significant challenges and drawbacks in its fabrication. A key issue with the trimethylamine aqueous solution method is water-induced membrane swelling. This swelling can cause the membrane to detach from its backing and create wrinkles, which is highly detrimental to assembling the membranes into a stack for use in electrochemical devices.

[0007] Another drawback is the slow diffusion rate in the liquid, requiring wide spacers to ensure the liquid can contact the multilayer polymer membrane. This requirement necessitates a large volume of liquid to amination a given amount of membrane. Furthermore, the concentration of the trimethylamine solution decreases after use, making it difficult to reuse effectively and resulting in significant waste generation.

[0008] The aqueous solution method also limits the amination of the entire roll of polymer film. Even with porous spacers of similar thickness to the polymer film, sufficient liquid contact cannot be achieved throughout the roll.

[0009] Further improvements are needed in the fabrication of anion exchange membranes to address the limitations of the trimethylamine aqueous solution method. Ideally, these methods would eliminate or reduce membrane swelling, increase diffusion rates, minimize waste generation, and allow for more efficient and scalable production processes, including the ability to amination rolls of the entire polymer membrane. Summary of the Invention

[0010] According to this disclosure, an improved method for manufacturing anion exchange membranes has been unexpectedly discovered, which overcomes the limitations of the trimethylamine aqueous solution method, eliminates or reduces membrane swelling, increases diffusion rate, minimizes waste generation, and allows for a more efficient and scalable production process, including the ability to amination rolls of the entire polymer membrane.

[0011] This technology includes articles, systems, and methods related to the amination of polymer membranes using trimethylamine gas to produce anion exchange membranes for use in electrochemical devices.

[0012] In one embodiment, a method for manufacturing an anion exchange membrane includes placing a polymer membrane in a pressure vessel, followed by removing air from the pressure vessel, for example by applying a first vacuum to the pressure vessel. The method then includes filling the pressure vessel with trimethylamine gas. Next, the method includes maintaining the trimethylamine gas in the pressure vessel for a first predetermined time sufficient to amination the polymer membrane, thereby providing an amination polymer membrane suitable for use as an anion exchange membrane. The method also includes removing residual trimethylamine gas from the pressure vessel, which can be accomplished, for example, by applying a second vacuum to the pressure vessel. Then, in a next step of the method, air is introduced into the pressure vessel, followed by the removal of the amination polymer membrane from the pressure vessel.

[0013] In an exemplary embodiment, a method for manufacturing an anion exchange membrane involves amination using trimethylamine gas. The method begins by placing a polymer membrane sheet or roll with thin spacers in a pressure vessel. Air is then removed from the vessel by applying a vacuum. Subsequently, the vessel is filled with trimethylamine gas at approximately 1 bar gauge pressure and a temperature of 30°C. The amination time is comparable to that of a liquid amination process. After amination, a vacuum is applied again to remove residual trimethylamine from the polymer membrane. Air is then introduced into the vessel as a final step. Optionally, an additional trimethylamine removal step can be performed by heat treatment at approximately 70°C for one hour.

[0014] The resulting membranes exhibit excellent adhesion properties, firmly adhering to their backing. Importantly, the membranes are almost or completely wrinkle-free, a significant improvement over conventional liquid-based amination methods. This wrinkle-free nature and maintained adhesion to the backing enhance the membranes' suitability for assembly into electrochemical device stacks, potentially improving performance and reliability across a wide range of applications.

[0015] The method of manufacturing anion exchange membranes using trimethylamine gas offers several advantages over conventional liquid-based amination processes. These advantages include improved uniformity of amination, the ability to process entire rolls of polymer membranes, reduced waste generation, and improved product quality. The resulting anion exchange membranes are also well-suited for a wide range of electrochemical applications, thereby enabling the development of clean energy technologies and chemical separation processes.

[0016] In other embodiments, the membrane of this disclosure can be useful in a variety of applications, including electrochemical devices. Therefore, in one aspect of this disclosure, an electrochemical device including the membrane of this disclosure can be provided. In another embodiment, a fuel cell including the membrane of this disclosure can also be provided.

[0017] Other applicable fields will become apparent from the description provided herein. The descriptions and specific examples in this invention are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0018] The accompanying drawings described herein are for illustrative purposes only and not for all possible implementations, and are not intended to limit the scope of this disclosure.

[0019] Figure 1 A flowchart illustrating a method for manufacturing an anion exchange membrane according to one embodiment of the present disclosure is provided.

[0020] Figure 2 This diagram illustrates the synthesis of a crosslinked copolymer of anion exchange membrane by amination with gaseous trimethylamine according to one embodiment of the present disclosure. Detailed Implementation

[0021] The following description of the techniques is merely an example of the subject matter, manufacture, and use of one or more inventions and is not intended to limit the scope, application, or use of any particular invention claimed in this application or any other application that may claim priority to this application or any patent granted therefrom. Regarding the disclosed methods, the order of the presented steps is exemplary in nature, and therefore the order of steps may differ in various embodiments, including cases where certain steps may be performed simultaneously, unless otherwise expressly stated. As used herein, “a / an” means “at least one / an” of the item is present; where possible, multiple / an such items may be present. Unless otherwise expressly stated, all numerical quantities in this specification should be understood to be modified with the word “about”, and all geometric and spatial descriptors should be understood to be modified with the word “substantially” to describe the broadest range of techniques. When applied to numerical values, “about” indicates that the calculation or measurement allows for some slight inaccuracy in the value (close to the accuracy of the value; approximate or reasonably close to the value; close). If for some reason "about" and / or "substantially" are not understood in this common sense in the art, then "about" or "substantially" as used herein at least indicates the variation that may arise from the common methods of measuring or using these parameters.

[0022] Unless otherwise expressly stated, all documents (including patents, patent applications, and scientific literature) referenced in the detailed embodiments are incorporated herein by reference. In the event of any conflict or ambiguity between the referenced documents and the detailed embodiments, the detailed embodiments shall prevail.

[0023] Although the open-ended term “comprising” is used herein as a synonym for non-limiting terms (e.g., including / containing or having) to describe and claim embodiments of the present technology, more restrictive terms (e.g., “consisting of” or “consisting essentially of”) may also be used to describe embodiments. Therefore, for any given embodiment that refers to materials, components, or method steps, the present technology also specifically includes embodiments consisting solely of or substantially consisting solely of those materials, components, or method steps, excluding other materials, components, or methods (for “consisting of”), excluding other materials, components, or methods that affect a material characteristic of the embodiment (for “substantially consisting of”), even if such other materials, components, or methods are not expressly described in this application. For example, a composition or method that refers to elements A, B, and C specifically contemplates consisting solely of A, B, and C, and embodiments consisting substantially solely of A, B, and C exclude element D, which may be described in the art, even if element D is not expressly excluded herein.

[0024] As stated herein, all percentages of composition are by weight of the total ingredients unless otherwise stated. Unless otherwise stated, the disclosure of a range includes endpoints and encompasses all distinct values ​​throughout the range and further subdivisions. Thus, for example, “A to B” or “about A to about B” includes both A and B. The disclosure of values ​​and ranges of values ​​for a particular parameter (e.g., quantity, weight percentage, etc.) does not exclude other values ​​and ranges of values ​​useful herein. It is conceivable that two or more specific example values ​​of a given parameter may define the endpoints of the range of values ​​for which that parameter can be claimed. For example, if parameter X is exemplified herein as having a value A, and also exemplified herein as having a value Z, it is conceivable that parameter X may have a range of values ​​from about A to about Z. Similarly, it is conceivable that the disclosure of two or more ranges of values ​​for a parameter (whether these ranges are nested, overlapping, or distinct) includes all possible combinations of ranges of values ​​for which claims can be made using the endpoints of the disclosed ranges. For example, if this article exemplifies parameter X as having a value ranging from 1 to 10, 2 to 9, or 3 to 8, it is also conceivable that parameter X could have other value ranges, including 1 to 9, 1 to 8, 1 to 3, 1 to 2, 2 to 10, 2 to 8, 2 to 3, 3 to 10, 3 to 9, etc.

[0025] When an element or layer is referred to as being “located in,” “joined to,” “connected to,” or “coupled to” another element or layer, it may be directly located in, joined to, connected to, or coupled to the other element or layer, or there may be intermediate elements or layers present. Conversely, when an element is referred to as being “directly located in,” “directly joined to,” “directly connected to,” or “directly coupled to” another element or layer, no intermediate elements or layers may be present. Other terms used to describe relationships between elements should be interpreted in a similar manner (e.g., “between” vs. “directly between”, “adjacent to” vs. “directly adjacent to”, etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the related listed items.

[0026] Although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or portion from another. Unless the context clearly indicates otherwise, the terms “first,” “second,” and other numerical terms used herein do not imply order or sequence. Therefore, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer, or portion discussed below may be referred to as a second element, component, region, layer, or portion.

[0027] For ease of description, this document may use spatial relative terms such as “inside,” “outside,” “below,” “lower,” “above,” “upper,” etc., to describe the relationship of an element or feature as shown in the figures to other elements or features. In addition to the orientations shown in the figures, spatial relative terms may be intended to cover different orientations of the device in use or operation. For example, if the device in the figure is flipped, an element described as “below” or “below” other elements or features will be oriented as “above” other elements or features. Thus, the exemplary term “below” can include both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or otherwise), and the spatial relative descriptive terms used herein will be interpreted accordingly.

[0028] This technology improves the manufacturing process of anion exchange membranes by addressing several key drawbacks of the conventional trimethylamine aqueous solution method. Specifically, it eliminates membrane swelling and wrinkling issues, improves diffusivity, reduces waste generation, and enables a more efficient and scalable production process, including the ability to ammoniate entire rolls of polymer membranes, by utilizing trimethylamine gas instead of an aqueous solution to enhance the amination step. This gas-based approach allows for better control of the amination process, resulting in higher quality membranes that maintain their structural integrity and are better suited for assembly into electrochemical device stacks.

[0029] like Figure 1 and Figure 2 As shown, this disclosure includes a method 100 for manufacturing anion exchange membranes. This method 100 utilizes trimethylamine gas to efficiently and uniformly amination the polymer membrane, thereby improving upon conventional water-based amination processes.

[0030] In one embodiment, method 100 may begin with step 110, which involves placing a polymer membrane in a pressure vessel. The polymer membrane may comprise a polycyclic olefin polymer, as a non-limiting example, as described in International Publication No. WO 2022 / 026794 A1, filed July 30, 2021, entitled “Polycyclic olefin polymers and anion exchange membranes derived therefrom”. Polycyclic olefin polymer membranes can provide desirable mechanical and chemical properties for the resulting anion exchange membrane. Those skilled in the art may also select other suitable chemical substances as needed for configuring the polymer membrane to be used as an anion exchange membrane after the amination process of this disclosure.

[0031] Polymer membranes can be supplied in the form of sheets or rolls, for example, with thin spacers. As used herein, the term "spacer" is defined as a thin layer or membrane of porous material. When used, such spacers and associated configurations allow gases to permeate efficiently throughout the membrane structure.

[0032] When using thin spacers, they can be placed between each sheet or layer. These spacers create small gaps or channels between the layers of the polymer membrane, allowing gas to efficiently permeate and circulate across the entire surface area of ​​the membrane. By maintaining these spaces between the membrane layers, the spacers ensure that trimethylamine gas can uniformly contact and react with all parts of the polymer, including areas that would otherwise be in close contact or adhere to each other. This arrangement promotes a more complete and uniform amination process across the entire membrane, resulting in a uniformly functionalized anion exchange membrane. As further described herein, the use of spacers can also help prevent the membrane from self-adheding or wrinkling during gas-based amination processes, a significant improvement over liquid-based methods that typically lead to membrane deformation.

[0033] Pressure vessels used in the amination process of trimethylamine gas can be specifically designed to safely handle corrosive and flammable gases. For example, during the amination process, it can maintain a pressure of about 1 bar gauge pressure (about 15 psig) and withstand temperatures of about 30°C (86℉), and in optional heat treatment processes, temperatures can reach 70°C (158℉). The vessel can be equipped with vacuum functions for removing air and evacuating residual gases, as well as mechanisms for controlling the inflow of air into the post-treatment system. Pressure vessels made of corrosion-resistant materials (e.g., stainless steel or special alloys) are considered suitable for the specified pressure and temperature conditions. It can also have suitable fittings for gas inlets, vacuum connections, and pressure / temperature monitoring devices to comply with relevant safety standards for handling hazardous gases. Those skilled in the art can select appropriate types and constructions of pressure vessels based on this understanding.

[0034] After the polymer membrane is placed, step 120 can be performed by removing air from the pressure vessel by applying a first vacuum. It should be understood that the air movement in step 120 is only one particular embodiment, and it is conceivable that the pressure vessel could be filled by purging it with trimethylamine gas without applying any vacuum. This would result in more exhaust gas and may therefore be less preferred than using a first vacuum, but it is expected to be sufficient in other respects. This step 120 ensures that subsequently introduced trimethylamine gas can effectively reach all portions of the polymer membrane. Removing air in method 100 also prevents any undesirable side reactions or contamination during the amination process.

[0035] As a non-limiting example, the pressure vessel can be equipped with a vacuum pump system connected via suitable valves and fittings. The vacuum pump system allows for the controlled evacuation of air from the vessel. Vacuum application can be performed in stages, starting with a coarse vacuum followed by a finer vacuum to ensure complete air removal. The vacuum level and duration can be optimized based on the vessel size and the amount of polymer membrane being processed. Furthermore, spacers used between membrane layers can help create pathways for more efficient air removal throughout the membrane stack or roll via vacuum. Pressure gauges and vacuum gauges can also be installed on the vessel to monitor the progress of air removal, ensuring sufficient vacuum is achieved before proceeding to the next step of introducing trimethylamine gas. This careful air removal process can advantageously create an environment where trimethylamine gas can interact effectively and uniformly with the polymer membrane, thereby promoting consistent amination across the entire membrane surface.

[0036] After removing the air, step 130, filling the pressure vessel with trimethylamine gas, can be performed. It should be understood that the vapor pressure of trimethylamine gas is relatively low, only 2.5 bar gauge pressure at 30°C and approximately 3.5 bar gauge pressure at 40°C. High pressures with trimethylamine gas can only be achieved at high temperatures. In this embodiment, trimethylamine gas can be introduced at a first predetermined pressure of approximately 1 bar gauge pressure, but the range of the first predetermined pressure can vary from ambient pressure to approximately 20 bar gauge pressure, depending on the specific requirements of the process. This pressure range can be selected to allow optimal gas permeation and reaction with the polymer membrane.

[0037] Non-limiting examples of a first predetermined pressure for introducing trimethylamine gas into a pressure vessel include about 1 bar gauge pressure, about 2 bar gauge pressure, or about 5 bar gauge pressure. The specific pressure can be adjusted according to factors such as the thickness of the polymer membrane, the desired amination rate, or the capacity of the pressure vessel. For example, higher pressures can be used for thicker membranes or when a faster amination process is required, while lower pressures can be suitable for thinner membranes or, preferably, a more gradual amination process. Furthermore, the pressure can be varied during the process, starting from a lower pressure and gradually increasing to ensure uniform gas permeation throughout the membrane layer. Those skilled in the art can also select intermediate pressures or pressure ranges within a specified range as needed, depending on the specific requirements of the polymer membrane and the intended application of the resulting anion exchange membrane.

[0038] In step 140, the trimethylamine gas can be held in a pressure vessel for a first predetermined time sufficient to amination the polymer film. For example, this duration can be comparable to the time required for a liquid amination process. For instance, the first predetermined time can be from about 1 hour to about 72 hours, more specifically, it can be about 24 hours. However, without being limited to any particular theory, it is believed that using a gas can achieve more uniform and efficient amination compared to liquid-based methods, thereby potentially reducing the overall processing time.

[0039] Non-limiting examples of maintaining trimethylamine gas in a pressure vessel for a first predetermined time include about 12 hours, about 18 hours, or about 36 hours. The specific duration can be adjusted based on factors such as the thickness of the polymer membrane, the desired degree of amination, or the reactivity of the particular polymer being processed. For example, a longer duration can be used for thicker membranes or when a higher degree of amination is required, while a shorter duration can be suitable for thinner membranes or when a lower degree of amination is sufficient. Furthermore, the amination time can be optimized in conjunction with other process parameters such as temperature and pressure to achieve an ideal balance between amination efficiency and processing time. Those skilled in the art can also select intermediate durations or time ranges within a specified range as needed, depending on the specific requirements of the polymer membrane and the expected performance of the resulting anion exchange membrane.

[0040] Step 140 may also include maintaining a first predetermined temperature, such as about 30°C, during the amination process. However, it should be understood that the first predetermined temperature may be varied in the range of about 20°C to about 80°C to optimize reaction kinetics and efficiency.

[0041] Non-limiting examples of maintaining the trimethylamine gas at a first predetermined temperature in a pressure vessel include about 25°C, about 40°C, or about 60°C. The specific temperature can be adjusted according to factors such as the composition of the polymer membrane, the desired amination rate, or the polymer's stability at high temperatures. For example, higher temperatures can be used to accelerate the amination process or when processing more thermally stable polymers, while lower temperatures can be suitable for more temperature-sensitive materials or, preferably, for a more gradual amination. Furthermore, the temperature can be varied during the process, starting from a lower temperature and gradually increasing to optimize reaction kinetics and ensure uniform amination throughout the membrane layer. Those skilled in the art can also select intermediate temperatures or temperature ranges within a specified range as needed, depending on the specific requirements of the polymer membrane and the expected performance of the resulting anion exchange membrane.

[0042] The ability to precisely control at least one of pressure and temperature is also considered another advantage of gas-based methods compared to conventional liquid-based methods. Those skilled in the art can also pre-determine and select any other suitable pressure and temperature for the trimethylamine gas within the pressure vessel, based on the scope of this disclosure.

[0043] After amination, a second vacuum can be applied to the pressure vessel in step 150 to remove residual trimethylamine from the polymer membrane. This step helps ensure effective removal of excess or residual trimethylamine gas, preventing over-amination or undesirable side reactions or interactions with the catalyst or electrolyte in the final application. The vacuum can be maintained for a second, predetermined period sufficient to remove substantially all residual trimethylamine gas from the polymer membrane and also from the pressure vessel.

[0044] Non-limiting examples of a second predetermined time for applying vacuum to remove residual trimethylamine gas include about 30 minutes, about 1 hour, or about 2 hours. The specific duration can be adjusted based on factors such as the volume of the pressure vessel, the amount of polymer membrane being processed, or the desired level of residual gas removal. For example, a longer vacuum application time may be used for larger pressure vessels or when processing more polymer membranes, while a shorter duration may be sufficient for smaller batches or when a lower level of residual gas removal is acceptable. Furthermore, the vacuum removal process can be enhanced by heating the pressure vessel to a second predetermined temperature (typically about 50°C to about 90°C, e.g., about 70°C), which can promote the desorption of trimethylamine from the polymer membrane. Those skilled in the art can also select intermediate durations or time ranges within a specified range as needed, depending on the specific requirements of the polymer membrane and the expected performance of the resulting anion exchange membrane.

[0045] Additionally, it should be understood that the pressure vessel can be purged with air instead of using a second vacuum to remove trimethylamine gas. In this case, the removal level of residual trimethylamine gas dissolved in the membrane may be lower, but with some optional heat treatment of the trimethylamine gas, the purging method is considered sufficient and can achieve the intended purpose.

[0046] If excessive trimethylamine gas remains dissolved in the polymer film, an additional step of heating the polymer film in air within a well-ventilated oven at approximately 60°C to approximately 90°C can be performed. If the polymer film is in roll form, it can first be unrolled in the long heating section of the oven. It should be understood that heating rolls or sheets under vacuum is difficult due to poor heat transfer in a vacuum; therefore, in some embodiments, heating the polymer film in air may be preferred.

[0047] Following the vacuum step, step 160, which introduces air into the pressure vessel, can be performed. This step serves several important purposes during the amination process. It helps normalize the pressure inside the vessel, preparing it for the removal of the amination polymer membrane as per step 170. The reintroduced control air balances the pressure inside the vessel with the external atmospheric pressure, which is crucial for safely opening the vessel and removing the amination polymer membrane.

[0048] Furthermore, this pressure normalization minimizes any pressure differentials that could damage or distort the membrane during extraction. The reintroduced control air also helps remove residual trimethylamine in the final stages. As fresh air enters the container, it helps displace and dilute any remaining traces of trimethylamine gas, further ensuring thorough removal of the reactive gas.

[0049] It should also be understood that step 160 can serve as a safety measure to mitigate the potential risks associated with opening containers that are already under vacuum or contain reactive gases. Furthermore, it serves as a quality control measure to ensure that the amination of the polymer film is exposed to standard atmospheric conditions before further processing or testing, which is crucial for the consistency of the final product's performance.

[0050] In some embodiments, an optional step (not shown) may be included, involving an additional trimethylamine removal step via heat treatment (e.g., in a well-ventilated oven). This heat treatment may be performed at a second predetermined temperature of about 50°C to about 90°C, more specifically at about 70°C. The heat treatment may also be performed for a second predetermined time, for example, about 30 minutes to about 2 hours, more specifically about 1 hour. Heat treatment can further ensure the complete removal of any residual trimethylamine and may also help stabilize newly formed quaternary ammonium groups in the polymer structure. Other suitable second predetermined temperatures and second predetermined times may also be employed as needed within the scope of this disclosure.

[0051] As described above, the polymer film used in method 100 may comprise a polycyclic olefin polymer having repeating units derived from norbornene-type monomers. At least one of these norbornene-type monomers may contain a side-chain alkyl halide group, which can serve as a reaction site for the amination process. In many cases, the side-chain alkyl halide group may be bromoalkyl, which provides a good balance between reactivity and stability. However, the use of other types of side-chain alkyl halide groups, such as alkyl iodide groups, alkyl chloride groups, and alkyl fluoride groups, may also be considered.

[0052] In some embodiments, the polymer membrane can also be provided as a prepolymer membrane, which is formed by solvent casting prior to the amination process. This prepolymer method allows for easier handling and processing of the membrane before the introduction of ionic groups. The ability to use prepolymers can be particularly advantageous for large-scale manufacturing processes. In this case, method 100 of this disclosure may also include a step of crosslinking the prepolymer membrane after amination. Crosslinking can enhance mechanical stability and control the swelling behavior of the resulting anion exchange membrane. Various techniques can be employed for the crosslinking step, such as heat treatment or the addition of specific crosslinking agents.

[0053] In some embodiments, the polymer membrane can be provided in rolls with spacers. The gas-based amination method 100 is particularly suitable for processing rolls of polymer membranes because it allows for more uniform gas permeation compared to liquid-based methods. This capability can significantly improve the scalability and efficiency of the manufacturing process.

[0054] It should be understood that the ion exchange capacity or IEC of the anion exchange membrane produced by method 100 can be at least 3 meq / g. Specifically, the ion exchange capacity of the anion exchange membrane can be from about 3 meq / g to about 5 meq / g. This high ion exchange capacity indicates a high degree of amination and can contribute to the membrane's effectiveness in a variety of electrochemical applications. The ion exchange capacity can be measured using standard titration techniques known in the art.

[0055] Due to its gas-based amination process, method 100 can produce amination-modified polymer films with unique properties. Compared to polymers amination using conventional liquid-based methods, these polymers exhibit improved amination uniformity and potentially better mechanical properties. The gas-based method allows for better control over the degree of amination and enables the production of more consistent products.

[0056] Anion exchange membranes containing polymers formed according to method 100 are also suitable for various electrochemical devices. These electrochemical devices may include fuel cells, electrolyzers, and chemical separation systems. The membranes can possess advantages such as high conductivity, good mechanical stability, and resistance to chemical degradation in alkaline environments.

[0057] Method 100 can also be particularly advantageous for large-scale production of anion exchange membranes. The ability to process entire rolls of polymer membranes and the potential for more uniform amination can contribute to improved manufacturing efficiency and product consistency. These factors can contribute to the commercial viability of anion exchange membrane-based technology.

[0058] It should be understood that, compared to liquid-based methods, the gas-based amination method 100 can also offer environmental benefits. Using gaseous trimethylamine reduces waste generation and minimizes the need for large quantities of liquid reagents. This can result in a more sustainable manufacturing process with reduced environmental impact.

[0059] Advantageously, due to the gas-based amination process, the anion exchange membrane manufactured according to method 100 of this disclosure can also have improved performance characteristics. In particular, compared with membranes produced using conventional liquid-based amination methods, such membranes can exhibit enhanced uniformity in their ionic properties and potentially better mechanical stability.

[0060] Furthermore, the anion exchange membrane manufactured according to method 100 can be provided with a selectively adhered backing before installation, such as during transport and storage in roll form. This backing provides additional structural support and ease of handling for the membrane. Using a backing is particularly advantageous in maintaining the integrity of the anion exchange membrane during its manufacture and subsequent assembly into an electrochemical device. This configuration can also be advantageous for large-scale production and processing of anion exchange membranes.

[0061] Importantly, the anion exchange membrane manufactured according to method 100 remains adhered to the backing in its entirety and is substantially wrinkle-free. This characteristic is a significant improvement over conventional liquid-based amination methods, which typically result in membrane swelling, separation from the backing, and wrinkling. The absence of wrinkles and the maintenance of adhesion to the backing greatly enhances the applicability of the membranes of this disclosure to stacks for a wide range of electrochemical applications, potentially improving the performance and reliability of the final device.

[0062] Example

[0063] Exemplary embodiments of this technology are provided with reference to the accompanying drawings.

[0064] Example 1: Gas-based amination of polymer membranes

[0065] Reference Figure 1 Polymer films comprising polycyclic olefin polymers having repeating units derived from norbornene-type monomers (including 5-(4-bromobutyl)bicyclic[2.2.1]hept-2-ene) can be prepared by solvent casting. The films have a thickness of approximately 30 μm and can be cut into 10 cm × 10 cm sheets.

[0066] Polymer membranes can be placed in a pressure vessel, with thin spacers between each membrane to allow gas permeation. The pressure vessel can be sealed, and a vacuum can be applied to remove air from the vessel. The vacuum can be maintained for 30 minutes to ensure complete air removal.

[0067] After the air removal step, the pressure vessel can be filled with trimethylamine gas. The pressure inside the vessel can be increased to 1 bar gauge pressure, and the temperature can be maintained at 30°C. These conditions can be maintained for 48 hours to allow the polymer film to be fully aminationd.

[0068] After the amination period, a vacuum can be applied to the pressure vessel to remove any remaining trimethylamine gas. This vacuum step can be maintained for 1 hour to ensure complete removal of excess trimethylamine. Subsequently, air is allowed to enter the vessel to restore it to atmospheric pressure.

[0069] As an additional step to ensure complete removal of residual trimethylamine, the amination-treated polymer film can be heat-treated at 70°C for 1 hour in a well-ventilated separate oven. After this treatment, the film can be cooled to room temperature.

[0070] As determined by titration, the ion exchange capacity (IEC) of the resulting amination-modified polymer membrane is approximately 3.0 meq / g to 5.0 meq / g. The membrane exhibits excellent mechanical properties and is expected to remain adhered to its backing without any visible wrinkles or deformation. When the hydroxide conductivity is tested, a value of approximately 180 mS / cm can be expected at 80 °C.

[0071] To assess the membrane's stability, the sample was immersed in a 1M NaOH solution at 80°C for 1000 hours. After this prolonged alkaline exposure, the membrane was expected to retain over 95% of its initial ion exchange capacity without exhibiting a significant decrease in mechanical properties.

[0072] It is expected that the amination-modified polymer membrane will be successfully integrated into fuel cell assemblies as anion exchange membranes. The fuel cell exhibits stable performance with minimal voltage decay after 500 hours of operation, indicating that the membrane is suitable for electrochemical applications.

[0073] Example 2: Gas-based amination of polymer membranes instead of water-based amination

[0074] like Figure 2 As shown, the preparation of the bifunctional crosslinked polymer used according to this disclosure can begin with the use of tetramethylhexanediamine or TMHDA. First, the polymer of this embodiment can be formed into a suitable three-dimensional object, such as a tubular composite material, hollow fiber, dense membrane sheet, or thin film composite material, which are commonly used as membrane materials. In particular, e-PTFE reinforced membranes can be produced from the crosslinked polymer by solution casting or other suitable methods.

[0075] according to Figure 2 The diagram illustrates how a precursor polymer in membrane form (e.g., where bromine can react with a polyfunctional amine such as TMHDA) forms a crosslinked polymer with the desired amount of crosslinking (depending on the intended end use). This crosslinking reaction can typically be carried out at ambient room temperature in a suitable solvent. Other suitable bases may also be used.

[0076] After the crosslinking reaction is complete, the polymer can be further treated with gaseous trimethylamine, as described above, to completely replace all the bromine with amino groups. Various other suitable amines can also be used.

[0077] Reference Figure 2 After treatment with gaseous trimethylamine, the functional groups still contain Br- as a counterion. As the final step in completing the membrane, such as... Figure 2 As shown, these Br are examples of non-limiting examples. - The ions will be exchanged for OH- by treatment with aqueous solutions of KOH or NaOH. -Ions. This alkaline treatment can be performed and is preferably carried out after the electrolytic stack is fully assembled.

[0078] The IEC of the membrane prepared according to this embodiment can be at least 3 meq / g, typically from about 3 meq / g to 5 meq / g or higher. In some embodiments, the IEC of the membrane prepared according to this embodiment can reach 4 meq / g or higher. Furthermore, the membrane prepared according to this embodiment can exhibit extremely high hydroxide conductivity exceeding 200 mS / cm at 80°C. In some embodiments, the membrane prepared according to this embodiment can exhibit hydroxide conductivity from about 100 mS / cm to about 190 mS / cm at 80°C. Therefore, in some embodiments, the membrane of this embodiment can have an IEC of at least 3 meq / g for at least 800 hours in an alkaline aqueous solution medium at a temperature from about 20°C to about 100°C.

[0079] Another advantageous characteristic of the membranes of this embodiment is that they can exhibit very high chemical stability, particularly in alkaline media. Therefore, in some embodiments, the membranes of this embodiment can be stable in alkaline aqueous media at temperatures ranging from about 20°C to about 100°C for at least 800 hours. In some other embodiments, the membranes of this embodiment can be stable in alkaline aqueous media at a temperature of about 80°C for 1000 hours.

[0080] Example 3: Gas amination of membrane-catalyst composite material

[0081] The gaseous amination process disclosed herein can be advantageously applied to composite materials containing both anion exchange membranes and catalyst layers. In this configuration, the catalyst layer contains a small amount of the same polymer as the membrane, which also requires amination. A pressure vessel is filled with the composite material consisting of a polymer membrane and an attached catalyst layer.

[0082] The gaseous amination process proceeds as previously described, with trimethylamine gas simultaneously permeating both the membrane and the catalyst layer. This uniform gas exposure ensures consistent amination throughout the composite structure. Gaseous trimethylamine can more easily permeate the porous catalyst layer, ensuring uniform amination of the polymer within it. This is particularly advantageous for maintaining the integrity of the catalyst layer-membrane interface, as gaseous amination minimizes expansion and potential deformation of the composite structure compared to liquid amination methods.

[0083] For such composites, the advantages of gas amination include increased efficiency, as it eliminates the need for separate amination steps for the membrane and catalyst layers, potentially reducing overall processing time. Furthermore, the gas-based approach allows for better control of amination process parameters, potentially yielding more consistent and reproducible results in the final composite structure. This approach demonstrates the applicability of gas amination methods in more complex electrode-membrane assemblies, highlighting its potential for producing high-quality anion exchange membranes with integrated catalyst layers for a wide range of electrochemical applications.

[0084] Exemplary embodiments are provided to make this disclosure sufficient and to fully communicate the scope to those skilled in the art. Numerous specific details, such as examples of specific components, apparatus, and methods, are set forth to provide a thorough understanding of embodiments of this disclosure. It will be apparent to those skilled in the art that specific details are not required, that exemplary embodiments may be embodied in many different forms, and that these should not be construed as limiting the scope of this disclosure. In some exemplary embodiments, well-known processes, well-known apparatus structures, and well-known technologies are not described in detail. Within the scope of this art, equivalent changes, modifications, and variations can be made to some embodiments, materials, compositions, and methods, yielding substantially similar results.

Claims

1. A method for manufacturing anion exchange membranes, comprising: Provide polymer films; The polymer membrane is placed in a pressure vessel; The pressure vessel was filled with trimethylamine gas; The trimethylamine gas is held in the pressure vessel for a first predetermined time sufficient to amination the polymer membrane, in order to provide an amination polymer membrane suitable for use as the anion exchange membrane; Allow air to enter the pressure vessel; and Remove the amination of the polymer membrane from the pressure vessel.

2. The method of claim 1, wherein the first predetermined time is from about 1 hour to about 48 hours.

3. The method of claim 2, wherein the first predetermined time is approximately 24 hours.

4. The method of claim 1, further comprising the step of maintaining the trimethylamine gas in the pressure vessel at a first predetermined pressure of approximately 20 bar gauge pressure at ambient pressure.

5. The method of claim 4, wherein the first predetermined pressure is approximately 1 bar gauge pressure.

6. The method of claim 1, further comprising the step of maintaining the trimethylamine gas in the pressure vessel at a first predetermined temperature of about 20°C to about 80°C.

7. The method of claim 6, wherein the first predetermined temperature is about 30°C.

8. The method according to claim 1, further comprising the following step: After the polymer membrane is placed in the pressure vessel, air is removed from the pressure vessel by applying a first vacuum to the pressure vessel; and After the trimethylamine gas is held in the pressure vessel for the first predetermined time, a second vacuum is applied to the pressure vessel to remove the residual trimethylamine gas, wherein the applied second vacuum for removing the residual trimethylamine gas is maintained for a second predetermined time sufficient to substantially remove all the residual trimethylamine gas from the amination polymer membrane.

9. The method of claim 1, wherein the step of removing residual trimethylamine gas further comprises heating the amination polymer membrane in the pressure vessel to a second predetermined temperature and holding it for a second predetermined time.

10. The method of claim 9, wherein the second predetermined temperature is about 50°C to about 90°C.

11. The method of claim 10, wherein the second predetermined temperature is about 70°C.

12. The method of claim 9, wherein the second predetermined time is from about 30 minutes to about 2 hours.

13. The method of claim 12, wherein the second predetermined time is about 1 hour.

14. The method of claim 1, wherein the polymer membrane comprises a polycyclic olefin polymer.

15. The method of claim 14, wherein the polycyclic olefin polymer has repeating units derived from norbornene monomers.

16. The method of claim 1, wherein the polymer film is a prepolymer film formed by solvent casting.

17. The method of claim 1, wherein the polymer film is provided in the form of a sheet or roll having thin spacers.

18. The method of claim 1, wherein the anion exchange membrane formed from the amination polymer membrane has an ion exchange capacity of at least about 3 meq / g.

19. The method of claim 18, wherein the ion exchange capacity is about 3 meq / g to about 5 meq / g.

20. An anion exchange membrane comprising an amination-modified polymer membrane formed by the method according to claim 1.

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