A poly (aryl azole) anion exchange membrane with high ionic conductivity and high dimensional stability, and a preparation method and application thereof

Abstract

The application discloses a kind of high ionic conductivity, high dimensional stability polyarylacridine anion exchange membrane and preparation method and application thereof, it is characterized by comprising the following steps: biphenyl, piperidone is dissolved in dichloromethane with acridone, trifluoroacetic acid and trifluoromethanesulfonic acid are added, stirring is carried out, and polyarylacridine polymer is obtained;Polyarylacridine polymer is dissolved in dimethyl sulfoxide, methyl iodide is added, and reaction is carried out, and quaternary ammonium polyarylacridine polymer is obtained;Quaternary ammonium polyarylacridine polymer is dissolved in organic solvent to obtain polymer membrane liquid, uniformly coated on flat substrate, dried, and polyarylacridine anion exchange membrane is obtained.The polymer main chain synthesized in the application does not have unstable aryl ether bond, has the characteristics of strong alkali resistance, and synthesis method is efficient and simple.The existence of acridine can promote the construction of microphase separation structure in membrane, form high-speed ion transmission channel in membrane, greatly improve the ion conductivity and water swelling resistance of membrane.

Description

Technical Field

[0001] This invention relates to the field of fuel cell membrane materials, specifically to a polyaryl acridine anion exchange membrane with high ionic conductivity and high dimensional stability, its preparation method, and its application. Background Technology

[0002] Anion exchange membrane fuel cells (AEMFCs) have attracted considerable attention as a clean and efficient energy conversion device. Anion exchange membranes (AEMs), which selectively transport hydroxide ions and block fuel at the cathode and anode, are the core components of AEMFCs. Developing and fabricating high-performance anion exchange membranes (AEMs) with high chemical stability, high ionic conductivity, and dimensional stability is crucial for the development of AEMFCs. With the deepening research into polymer degradation mechanisms and the understanding of the degradation of aryl ether bonds in alkaline environments in recent years, ether-free polymer backbones have received significant attention in the field of ion exchange membrane research due to their high chemical stability. Methods for preparing polymer backbones without aryl ether bonds mainly include radiation grafting, ring-opening metathesis polymerization, and metal-catalyzed coupling reactions. The chemical stability of polyethylene anion exchange membranes prepared by radiation grafting needs further improvement; the ring-opening metathesis polymerization method is relatively complex and difficult to scale up; in addition, metal residues may remain in metal-catalyzed coupling reactions; the synthesis of ether-free polymers by superacid catalysis has unparalleled advantages over polymers prepared by traditional condensation, including simple preparation, mild reaction conditions, low cost (no need for expensive palladium catalysts), and high molecular weight polymers, resulting in membrane materials with good mechanical properties. Therefore, superacid catalysis is a promising strategy for the synthesis of AEM materials.

[0003] Increasing the ion exchange capacity (IEC) is a simple way to achieve higher conductivity. However, higher ion exchange capacity often leads to excessive water absorption and swelling, which can result in decreased dimensional and mechanical stability. Designing polymer structures to create microphase-separated morphologies is considered an effective method to improve conductivity without sacrificing dimensional stability. Therefore, preparing high-performance AEMs—that is, high ionic conductivity, high chemical stability, and dimensional stability—is crucial for improving the performance of AEMFCs. Summary of the Invention

[0004] Based on this, the present invention provides a polyaryl acrylidine anion exchange membrane with high ionic conductivity and high dimensional stability, its preparation method, and its application, to solve the technical problem of the mutual constraint between high ionic conductivity and dimensional stability in anion membranes used in fuel cells in the prior art. Acrylidine ketones are aromatic heterocyclic compounds containing nitrogen elements. Due to their rigid planar conjugated structure, they cannot rotate. In this invention, acrylidine ketones are introduced into an ether-free polymer backbone to prepare novel polyaryl acrylidine-piperidine polymers. The introduction of non-rotatable acrylidine, due to the π-π stacking effect between the main chains, can promote the formation of better microphase separation morphology of the membrane, thereby obtaining higher ionic conductivity and lower dimensional swelling ratio.

[0005] To achieve the above objectives, the present invention provides a method for preparing a polyaryl acridine anion exchange membrane with high ionic conductivity and high dimensional stability, comprising the following steps:

[0006] 1) Biphenyl, piperidone and 10-methyl-9(10H)-acridone (acridone for short) were dissolved in dichloromethane, and trifluoroacetic acid and trifluoromethanesulfonic acid were added. The mixture was stirred to carry out the reaction and a polyaryl acridine polymer prepared based on superacid catalysis was obtained.

[0007] 2) Dissolve the polyaryl acridine polymer obtained in step 1) in dimethyl sulfoxide, then add iodomethane. After the reaction is complete, precipitate, filter, and wash to obtain the quaternized polyaryl acridine polymer.

[0008] 3) Dissolve the quaternized polyaryl acridine polymer obtained in step 2) in an organic solvent to obtain a uniform polymer membrane solution. Coat the polymer membrane solution uniformly on a flat substrate and dry it to obtain a polyaryl acridine anion exchange membrane with high ionic conductivity and high dimensional stability based on superacid catalysis.

[0009] As a further preferred technical solution of the present invention, in step 1), the reaction is carried out in an ice bath. After the reaction is completed, the polymer solution obtained after the reaction is poured into ethanol for precipitation, the precipitate is filtered out and washed; the filter is placed in an oven to dry, and the polyaryl acridine polymer prepared based on superacid catalysis is obtained.

[0010] As a further preferred technical solution of the present invention, in step 2), after the reaction is completed, the solution is slowly poured into an ethyl acetate solution for precipitation, filtered to obtain a light yellow solid, and washed multiple times with ethyl acetate to obtain a quaternized polyaryl acridine polymer.

[0011] As a further preferred technical solution of the present invention, in step 3), the substrate is a glass plate.

[0012] As a further preferred technical solution of the present invention, in step 3), the drying temperature is 70°C and the time is 6 to 12 hours.

[0013] As a further preferred technical solution of the present invention, in step 1), the ratio of each reactant is: biphenyl 1 equiv, piperidinone and 10-methyl-9(10H)-acridinone 1.4 equiv, trifluoroacetic acid 1 equiv and trifluoromethanesulfonic acid 15 equiv; in step 2), the ratio of each reactant is: polyaryl acridine polymer 1 equiv and iodomethane 1.8 equiv.

[0014] According to another aspect of the present invention, the present invention also provides a polyaryl acridine anion exchange membrane with high ionic conductivity and high dimensional stability.

[0015] According to another aspect of the present invention, the present invention also provides the application of a polyaryl acrylidine anion exchange membrane with high ionic conductivity and high dimensional stability in an alkaline anion exchange membrane fuel cell.

[0016] The preparation method of this invention is efficient and simple, with mild reaction and readily available materials, which is conducive to large-scale industrial production. By adjusting the content of acridinium, the microphase separation morphology of the synthesized basic membrane can be controlled, thereby controlling the ionic conductivity, water absorption, mechanical strength, and other properties of the polyaryl acridinium anion exchange membrane.

[0017] The polymer synthesized in this invention has no unstable aryl ether bonds in its main chain and exhibits strong alkali resistance. Simultaneously, the presence of acridine promotes the construction of microphase separation structures within the membrane, forming high-speed ion transport channels, thereby significantly improving the membrane's ion conductivity and resistance to water swelling.

[0018] The polyaryl acridine anion exchange membrane prepared by this invention exhibits excellent mechanical properties, low swelling, and excellent chemical stability, and has broad application prospects in alkaline anion exchange membrane fuel cells. Attached Figure Description

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] Figure 1 This is a schematic diagram illustrating the synthesis of the quaternized polyarylepiperidine polymer of the present invention;

[0021] Figure 2 These are the 1H NMR spectra of the polyarylpiperidine polymer and the quaternized polyarylpiperidine polymer of Example 1 of the present invention;

[0022] Figure 3 These are the water content and swelling ratio curves of the anion exchange membranes of Example 1 and Comparative Example 1 of the present invention as a function of temperature.

[0023] Figure 4This is a comparison diagram of the mechanical properties of the anion exchange membranes of Example 1 and Comparative Example 1 of the present invention;

[0024] Figure 5 These are transmission electron microscope (TEM) comparison images of the anion exchange membranes of Example 1 (right) and Comparative Example 1 (left) of the present invention;

[0025] Figure 6 This is a comparison graph of the OH- conductivity of the anion exchange membranes of Example 1 and Comparative Example 1 at different temperatures.

[0026] Figure 7 The anion exchange membranes of Example 1 and Comparative Example 1 of this invention were immersed in 2M NaOH at 80°C. - The curve showing the change in electrical conductivity over time.

[0027] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0028] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0029] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0030] Figure 1 The diagram shown is a schematic diagram of the synthesis of the quaternized polyaryl acridine polymer of the present invention; wherein: X is the molar percentage content of acridine ketone, X = 5%-30%, 1-X = 70%-95%.

[0031] The preparation method of the polyaryl acrylidine anion exchange membrane (hereinafter referred to as polyaryl acrylidine anion exchange membrane) with high ionic conductivity and high dimensional stability of the present invention comprises the following steps:

[0032] 1) Biphenyl, piperidone, and 10-methyl-9(10H)-acridone (hereinafter referred to as acridinone) were dissolved in dichloromethane. Trifluoroacetic acid and trifluoromethanesulfonic acid were added under ice bath conditions, and the mixture was stirred to carry out the reaction. After the reaction was completed, the polymer solution obtained after the reaction was poured into ethanol for precipitation. The precipitate was filtered out and washed clean. The filter was placed in an oven to dry, and the polyaryl acridinium polymer prepared based on superacid catalysis was obtained, denoted as PABP.

[0033] 2) Dissolve the polyarylpiperidine polymer obtained in step (1) in an appropriate amount of dimethyl sulfoxide, and then add an appropriate amount of iodomethane. After the reaction is complete, slowly pour the solution into an ethyl acetate (EA) solution to precipitate. Filter to obtain a light yellow solid. Wash with ethyl acetate three times to obtain a quaternized polyaryl acridine polymer, denoted as QPABP-X, where X is the molar percentage of acridine ketone.

[0034] 3) Dissolve the quaternized polyarylpiperidine polymer in (2) in an organic solvent to obtain a uniform polymer membrane solution. Coat the membrane solution uniformly on a flat glass plate and dry it at 70°C for 12 hours to obtain a polyaryl acridine anion exchange membrane prepared based on superacid catalysis.

[0035] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described in detail below through specific embodiments.

[0036] Example 1:

[0037] A method for preparing a polyaryl acridine anion exchange membrane, comprising the following steps:

[0038] (1) Preparation of polyaryl acridine polymer PABP-10

[0039] 1.542 g of biphenyl, 0.272 g of acridinone, and 1.44 mL of N-methyl-4-piperidinone were dissolved in 13 mL of dichloromethane. 1.15 mL of trifluoroacetic acid and 15 mL of trifluoromethanesulfonic acid were added under ice bath conditions. The mixture was stirred under ice bath conditions for 6 hours. After the reaction was completed, the resulting viscous, dark green solution was poured into 1 M NaOH solution to obtain a white fibrous product. The product was filtered and washed three to five times with deionized water until neutral to obtain the polyarylpiperidine polymer PABP-10, which was then dried for later use.

[0040] (2) Preparation of quaternized polyaryl acridine polymer QPABP-10

[0041] Dissolve 0.5g of the polyarylpiperidine polymer obtained in step (1) in 10mL of dimethyl sulfoxide, add 215μL of iodomethane solution, react at room temperature for 18h, precipitate in 100mL of ethyl acetate and wash, filter to obtain quaternized polyarylacridine polymer.

[0042] (3) Preparation of polyaryl acridine anion exchange membrane QPABP-10

[0043] Take 0.3g of the quaternized polyarylepiperidine polymer obtained in step (2) and dissolve it in 10mL of dimethyl sulfoxide to obtain a uniform polymer membrane solution. Coat the membrane solution uniformly on a flat glass plate and dry it at 60℃ for 12 hours. Peel the membrane off the glass plate and soak it in 1M NaOH solution for 24 hours. Then wash the membrane with deionized water to remove excess sodium hydroxide and obtain the hydroxide-type QPABP-10 anion exchange membrane.

[0044] Comparative Example 1:

[0045] A method for preparing a poly(biphenylpiperidine) anion exchange membrane, used as a control group in Example 1, wherein the amount of acridinium used is 0 wt%, and the specific steps are as follows:

[0046] (1) Preparation of poly(benzylpiperidine) polymer (PBPIP)

[0047] 1.2 g of biphenyl and 1068 μL of N-methyl-4-piperidinone were dissolved in 6 mL of dichloromethane. 594 μL of trifluoroacetic acid and 6.9 mL of trifluoromethanesulfonic acid were added under ice bath conditions. The mixture was stirred under ice bath conditions for 4 hours. After the reaction was completed, the resulting viscous, dark red solution was poured into 1 M NaOH solution to obtain a white fibrous product. The product was filtered and washed three to five times with deionized water until neutral to obtain polybiphenyl piperidine polymer (PBPIP). The product was dried and set aside for later use.

[0048] (2) Preparation of quaternized polyphenylpiperidine polymer QPAPIP

[0049] Dissolve 0.5g of the polyarylpiperidine polymer obtained in step (1) in 10mL of dimethyl sulfoxide, add 230μL of iodomethane solution, react at room temperature for 10h, precipitate in 100mL of ethyl acetate and wash, filter to obtain quaternized polybiphenylpiperidine polymer QPBPIP.

[0050] (3) Preparation of poly(biphenylpiperidine) anion exchange membrane QPBPIP

[0051] Take 0.3g of the quaternized polyarylepiperidine polymer obtained in step (2) and dissolve it in 10mL of dimethyl sulfoxide to obtain a uniform polymer membrane solution. Coat the membrane solution uniformly on a flat glass plate and dry it at 60℃ for 12 hours. Peel the membrane off the glass plate and soak it in 1M NaOH solution for 24 hours. Then wash the membrane with deionized water to remove excess sodium hydroxide and obtain a hydroxide-type QPBPIP anion exchange membrane.

[0052] Figure 2The 1H NMR spectra of polymers PABP-10 and QPABP-10 obtained in steps (1) and (2) of Example 1 were obtained. Specifically, the characteristic peaks of H on the benzene rings of biphenyl and acridinone appeared at 7.05-7.98 ppm, and the signal peak at 9.29 ppm was attributed to the characteristic peak of protonated H in acridin. Calculations of the product of peaks ab and c, along with the aforementioned NMR data, confirmed the successful synthesis of PABP-10. After quaternization with excess iodomethane, the PABP-10 polymer was converted to QPABP-10 polymer via a piperidine quaternization reaction. After quaternization with iodomethane, the methyl peak on piperidine shifted from 2.91 ppm to 3.28 ppm, demonstrating the successful synthesis of QPABP-10 polymer.

[0053] Figure 3 The water resistance and swelling properties of the QPABP-10 anion exchange membrane prepared in Example 1 and the QPBPIP anion exchange membrane prepared in Comparative Example 1 were characterized. The QPBPIP and QPABP-10 anion exchange membranes were immersed in glass bottles filled with water at a certain temperature for 24 hours. The water content and linear swelling rate of the membranes were measured. The water content of the QPBPIP membrane at 30°C was 17.7 wt%, and the linear swelling rate was 25%. Upon heating to 80°C, its water content and linear swelling rate were 64.21 wt% and 42%, respectively. The water content of the QPABP-10 membrane at 30°C was 28.57 wt%, and the linear swelling rate was 31%. Upon heating to 80°C, its water content and linear swelling rate were 89.92 wt% and 56%, respectively. Figure 3 As can be seen, the water content and linear swelling rate of the anion exchange membrane increase with increasing temperature. However, the introduction of acridinone improves the dimensional stability of the membrane, which can ensure the mechanical integrity of the membrane when the fuel cell is running at high temperatures.

[0054] Figure 4 The mechanical properties of the QPABP-10 anion exchange membrane prepared in Example 1 and the QPBPIP anion exchange membrane prepared in Comparative Example 1 were characterized. The changes in tensile strength (Ts) and elongation at break (Eb) of the membranes are shown in the figure. Figure 2 As shown. The tensile strength of the QPABP-10 membrane prepared in Example 1 is 35.15 MPa, and the elongation at break is 21.49%; the tensile strength of the QPBPIP membrane prepared in Example 1 is 23.44 MPa, and the elongation at break is 18.77%. The introduction of acridinone improves the mechanical properties of the membrane and also meets the requirements for fuel cell applications.

[0055] Figure 5 The microphase separation morphology of the anion exchange membranes prepared in Example 1 and Comparative Example 1 of this invention was characterized using transmission electron microscopy (TEM). Figure 5It can be clearly seen that the QPABP-10 anion exchange membrane prepared in Example 1 has a clear hydrophilic-hydrophobic microphase separation morphology. The hydrophilic regions are interconnected to form interconnected hydrophilic channels, which provide unobstructed channels for ion transport, thereby improving ion transport efficiency and thus improving the conductivity of the anion exchange membrane. In addition, the hydrophobic regions provide mechanical support for the anion exchange membrane, ensuring the mechanical stability of the membrane.

[0056] Figure 6 The OH content of the anion exchange membranes prepared in Example 1 and Comparative Example 1 of this invention at different temperatures. - The conductivity was measured, and the OH content of the QPBPIP anion exchange membrane at 30°C was measured. - The conductivity is 29.59 mS / cm, and it increases with temperature up to 80℃. - The conductivity increased to 57.05 mS / cm. The OH- ion exchange capacity of the QPABP-10 anion exchange membrane at 30°C... - The conductivity is 65.60 mS / cm, and it increases with temperature up to 80℃. - The conductivity increased to 166.35 mS / cm. It is evident that the membrane conductivity increases with increasing temperature, which is due to the increased mobility of anions with temperature. The conductivity of the QPABP-10 anion exchange membrane shows a more pronounced trend of increasing with temperature, which corresponds to the phase separation morphology of the membrane; that is, the introduction of acridinone results in larger ion channels, which is beneficial for ion transport.

[0057] Figure 7 The alkali resistance of the QPABP-10 anion exchange membrane prepared in Example 1 and the QPBPIP anion exchange membrane prepared in Comparative Example 1 was tested. After immersing QPBPIP and QPABP-10 in a 2M NaOH solution at 80°C for 600 h, the IEC of the QPBPIP membrane decreased by 10%, and the OH... - The conductivity decreased by 15.5%; while PABP-10 only decreased by 2.3%, OH - The conductivity decreased by 6%, indicating that the introduction of acridinone is beneficial to improving the stability of the membrane.

[0058] Example 2 and Example 3

[0059] Following the preparation method of the poly(biphenylpiperidine) anion exchange membrane in Example 1 above, only the amount of acridine ketone was changed, resulting in polyaryl acridine anion exchange membranes with acridine ketone content of 5% and 30%, respectively designated as QPABP-5 and QPABP-30. The performance test results of the polyaryl acridine anion exchange membranes prepared in Examples 1-3 and Comparative Example 1 are shown in Table 1.

[0060] Table 1

[0061]

[0062] Note: The table shows data on water absorption swelling and tensile strength of the membrane under different acridinium contents (0%, 5%, 10%, 30%). Comparison reveals that the introduction of an appropriate amount of acridinium improves the membrane's ionic conductivity, tensile strength, and other properties. Taking QPABP-10 as an example, even with a high swelling ratio, the tensile strength can reach 35 MPa, thus meeting the requirements for fuel cell use and demonstrating the membrane's high dimensional stability. Example 1 represents the optimal solution of this invention.

[0063] Based on the above method, the polymer backbone synthesized in this invention has no unstable ether bonds and exhibits strong alkali resistance. The synthesis method is simple and efficient. The addition of acridinone further improves the alkali resistance of the membrane, extends its service life, and enhances the hydrophilic / hydrophobic microphase separation structure of the anion exchange membrane, forming high-speed ion transport channels within the membrane and giving it high ion conductivity. The anion exchange membrane prepared by this invention exhibits excellent mechanical properties, low swelling, and excellent chemical stability, showing broad application prospects in alkaline anion exchange membrane fuel cells.

[0064] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. A method for preparing a polyaryl acridine anion exchange membrane with high ionic conductivity and high dimensional stability, characterized in that, Includes the following steps: 1) 1.542 g biphenyl, 0.272 g piperidinone and 1.44 mL 10-methyl-9(10H)-acridinone were dissolved in dichloromethane, 1.15 mL trifluoroacetic acid and 15 mL trifluoromethanesulfonic acid were added, and the mixture was stirred to carry out the reaction to obtain a polyaryl acridine polymer prepared based on superacid catalysis; 2) Dissolve the polyaryl acridine polymer obtained in step 1) in dimethyl sulfoxide, then add iodomethane. After the reaction is complete, precipitate, filter, and wash to obtain the quaternized polyaryl acridine polymer. 3) Dissolve the quaternized polyaryl acridine polymer obtained in step 2) in an organic solvent to obtain a uniform polymer membrane solution. Coat the polymer membrane solution uniformly on a flat substrate, dry it, and soak it in 1 M NaOH solution for 24 hours to obtain a polyaryl acridine anion exchange membrane with high ionic conductivity and high dimensional stability prepared based on superacid catalysis.

2. The method for preparing the polyaryl acridine anion exchange membrane with high ionic conductivity and high dimensional stability according to claim 1, characterized in that, In step 1), the reaction is carried out in an ice bath. After the reaction is completed, the polymer solution obtained after the reaction is poured into ethanol for precipitation, the precipitate is filtered out and washed. The filtrate was dried in an oven to obtain a polyaryl acridine polymer prepared based on superacid catalysis.

3. The method for preparing the polyaryl acridine anion exchange membrane with high ionic conductivity and high dimensional stability according to claim 1, characterized in that, In step 2), after the reaction is complete, the solution is slowly poured into an ethyl acetate solution to precipitate, filtered to obtain a light yellow solid, and washed several times with ethyl acetate to obtain a quaternized polyaryl acridine polymer.

4. The method for preparing the polyaryl acridine anion exchange membrane with high ionic conductivity and high dimensional stability according to claim 1, characterized in that, In step 3), the substrate is a glass plate.

5. The method for preparing the polyaryl acridine anion exchange membrane with high ionic conductivity and high dimensional stability according to claim 1, characterized in that, In step 3), the drying temperature is 70℃ and the time is 6~12 hours.

6. A polyaryl acridine anion exchange membrane with high ionic conductivity and high dimensional stability, characterized in that, Prepared by the method described in any one of claims 1-5.

7. An application of a polyaryl acridine anion exchange membrane with high ionic conductivity and high dimensional stability, characterized in that, The alkaline anion exchange membrane fuel cell uses the polyaryl acridine anion exchange membrane with high ionic conductivity and high dimensional stability as described in claim 6.

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