An ionomer based on a flexible main chain, an anion exchange membrane and a preparation method thereof

Abstract

The present invention provides an ionomer based on a flexible main chain, an anion exchange membrane and a preparation method thereof. The preparation method of the anion exchange membrane includes: mixing 1,7-dichloro-4-heptanone with a trimethylamine solution in a first organic solvent to obtain N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride; mixing it with a hydroxyl-containing all-carbon flexible polymer main chain, an aromatic aldehyde and / or an aromatic ketone in the presence of a second organic solvent and a catalyst to obtain an ionomer based on a flexible main chain; mixing the ionomer based on a flexible main chain with a third organic solvent, drying the mixture into a film, and soaking the film in an alkali solution to obtain an anion exchange membrane with hydroxide as the anion. The ionomer based on a flexible main chain and / or the anion exchange membrane prepared by the present invention have the characteristics of excellent mechanical properties, high ionic conductivity, low swelling rate, high antioxidant stability, high alkali resistance stability, as well as high fuel cell performance and water electrolysis performance.

Description

Technical Field

[0001] The present invention relates to the technical fields of fuel cells and water electrolysis technologies, and in particular to an ionomer based on a flexible main chain, an anion exchange membrane and a preparation method thereof. Background Art

[0002] An anion exchange membrane (AEM) is a type of polymer electrolyte composed of cations fixed on the main chain and freely moving anions, and can be used in energy conversion devices such as zero-gap alkaline water electrolyzers and anion exchange membrane fuel cells. With the increasing emphasis on hydrogen production and utilization by the state in recent years, the demand for developing high-performance AEMs has become more prominent. The AEM plays a role of conducting ions and isolating electrodes in the device, so it is required to have high ion conductivity and excellent mechanical properties. And because the working environment is often alkaline, the AEM also needs to have high alkali stability. In addition, since it is used as an ionomer in the catalytic layer, the ionomer for preparing the AEM also needs to have good solubility.

[0003] Acetals are a class of organic compounds in which two alkoxy groups and a hydrogen atom are attached to the same carbon. Ketals are a class of organic compounds in which the same carbon is connected to two alkoxy groups and two hydrocarbon groups. Acetals and ketals are unstable in acidic aqueous solutions but stable to bases and oxidants. This structure is widely used for the protection of carbonyl groups, and this kind of structure has natural stability advantages for the preparation of AEMs. The literature (Int J Hydrogen Energ. 46, 2021, 37007—37016) used the acetal reaction of 4-imidazolylbenzaldehyde with hydroxyl groups to synthesize a crosslinking agent with imidazole-functionalized polyvinyl alcohol as a functional macromolecule, and then the macromolecular crosslinking agent reacted with brominated polyphenylene ether to synthesize crosslinked AEMs. It was found that after soaking in 1 M NaOH solution for 1000 h, the mechanical properties and ionic conductivity of the c-91 membrane with the best comprehensive performance showed obvious attenuation. However, the authors used spectroscopic characterization to confirm that the degradation occurred in the imidazole ring, rather than the acetal group. The authors combined flexible chains and rigid chains using a crosslinking strategy, which helped to obtain an anion exchange membrane with both rigidity and flexibility. However, due to the low ion density, the ion exchange capacity and ionic conductivity of the target product were both low. For example, the ion exchange capacity of c-91 was 1.54 mmol / g, and the ionic conductivity at 80 °C was 78.8 mS / cm. The literature (Macromolecules 54, 2021, 7900—7909) grafted p-trifluoromethylbenzaldehyde and 4-imidazolecarboxaldehyde onto polyvinyl alcohol using an acetal reaction, and introduced a cation-containing long-chain crosslinking agent into the anion exchange membrane using the Menshutkin reaction of methylene bromide with imidazole. After the alkali resistance stability experiment (6 M NaOH, 80 °C, 240 h), the loss of ionic conductivity was close to 35%. The authors used nuclear magnetic carbon spectrum experiments to confirm that the reason for the degradation of AEMs was that the carbon atom adjacent to the cation was nucleophilically attacked by a hydroxyl group, resulting in the opening of the carbon chain of the crosslinking agent, and the degradation site was not the acetal group. Due to the high crosslinking density, the obtained AEMs had a high ion exchange capacity (1.8~2.9 mmol / g), a high water content (282%~726%, room temperature), and thus a high ionic conductivity (29.6~66.1, room temperature). However, the high water content led to a high swelling rate and thus poor mechanical properties (0.7~1.4 MPa). In addition, this kind of crosslinked AEMs could not obtain a soluble ionomer and could not be used as the ionomer in the catalyst layer of the membrane electrode.

[0004] In summary, although acetals and ketals have high alkali resistance, it is still very necessary to develop high-performance ionomers and anion exchange membranes based on this kind of structure. Summary of the Invention

[0005] In view of this, the present invention provides an ion polymer based on a flexible main chain, an anion exchange membrane, and a preparation method thereof, which have high stability, high ionic conductivity, and high mechanical properties.

[0006] In a first aspect, the present invention provides an ion polymer based on a flexible main chain, and the polymer is represented by formula (I):

[0007] (I);

[0008] In formula (I), x, y, z, and t respectively represent the molar ratios of the respective structural units in the ion polymer; wherein, the value range of 2x + 2y is 0.4 to 1.0, and 2x + 2y + z + t = 1.0; R includes at least one benzene ring.

[0009] On the basis of the above technical solutions, preferably, the value range of x is 0.1 to 0.5, the value range of y is 0.1 to 0.5, the value range of z is 0 to 0.6, and the value range of t is 0 to 0.4.

[0010] In a second aspect, the present invention relates to a method for preparing the above-mentioned ion polymer based on a flexible main chain, and the ion polymer based on a flexible main chain is prepared by acetalization and / or ketalization of a fully carbon flexible polymer main chain, an aldehyde or a ketone, and a quaternization product of 1,7-dichloro-4-heptanone.

[0011] First, the fully carbon flexible polymer main chain of the present invention contains hydroxyl groups (-OH), which, as active functional groups, can ensure good compatibility between the polymer and other reactants, provide reaction sites for subsequent chemical modification, enable the polymer containing hydroxyl groups to effectively combine with other reactants, and thus introduce new functional side chains. The presence of hydroxyl groups helps to promote intermolecular hydrogen bonding or other types of crosslinking, which can improve the mechanical properties and thermal stability of the material. In addition, the acetal and / or ketal structures formed by acetalization and / or ketalization reactions can further stabilize the polymer network and endow the material with better physical properties.

[0012] Secondly, the quaternary ammonium product of 1,7-dichloro-4-heptanone exhibits excellent ionic conductivity, which can significantly enhance the application potential of the final polymer as an ionic conductor and electrolyte material, and is suitable for energy storage devices such as batteries and supercapacitors. This compound shows high chemical and thermal stability, ensuring the long-term performance of the material under harsh conditions, which is crucial for the development of high-performance and long-life products. In addition, the functional side chains introduced by specific quaternary ammonium reagents not only enhance the ionic conductivity but also provide additional functionalization sites for subsequent chemical modification, such as two chlorine atoms, increasing the design flexibility of the material. Meanwhile, 1,7-dichloro-4-heptanone is easy to undergo quaternary ammonium reaction, and this reaction has high selectivity and controllability, allowing precise control of the product properties and achieving high customization of the final material performance. The quaternary ammonium product has good compatibility with the hydroxyl-containing all-carbon flexible polymer backbone and other reactants (such as aromatic aldehydes or ketones), promoting the formation of multifunctional composite structures, and also maintaining environmental adaptability, being able to stably perform under various conditions.

[0013] By adopting the above technical solutions, not only have functional ionic groups and aromatic structures been successfully introduced while maintaining the original flexibility of the polymer, significantly enhancing the ionic conductivity, chemical stability, and thermal stability of the material, but also the mechanical properties and processability have been enhanced.

[0014] Based on the above technical solutions, preferably, the all-carbon flexible polymer backbone is a hydroxyl-containing all-carbon flexible polymer backbone, and its structure is shown in formula (a):

[0015] (a);

[0016] In formula (a), both m and n represent the molar proportions of each structural unit in the polymer; among them, m + n = 1.0.

[0017] Based on the above technical solutions, the aldehyde or ketone is an aromatic aldehyde or aromatic ketone; preferably, the aromatic aldehyde and / or the aromatic ketone is selected from at least one of the following structures:

[0018] .

[0019] Based on the above technical solutions, the 1,7-dichloro-4-heptanone is shown in the following formula (b):

[0020] (b).

[0021] Based on the above technical solutions, preferably, the quaternary ammonium product of 1,7-dichloro-4-heptanone is shown in the following formula (c):

[0022] (c).

[0023] Based on the above technical solutions, preferably, the method includes the following steps:

[0024] S1. 1,7-dichloro-4-heptanone reacts with trimethylamine solution in a first organic solvent to obtain N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride;

[0025] S2. A hydroxyl-containing all-carbon flexible polymer backbone reacts with the N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride prepared in step S1, an aromatic aldehyde and / or an aromatic ketone under the action of a second organic solvent and a catalyst to undergo an acetal and / or ketal reaction, obtaining an ionic polymer based on a flexible backbone.

[0026] By adopting the above technical means, the present invention introduces specific functional side chains (such as ionic groups and aromatic aldehyde / ketone structures). This method can significantly improve the chemical diversity and functionality of all-carbon flexible polymers. These modifications can enhance the electrical conductivity, thermal stability, mechanical flexibility, and other physicochemical properties of the materials, making the materials more suitable for applications in fields with high-performance requirements.

[0027] Based on the above technical solutions, preferably, in step S1, the addition amount of the trimethylamine is 3 to 5 times the molar amount of chlorine atoms in the 1,7-dichloro-4-heptanone; the mass-volume ratio of the 1,7-dichloro-4-heptanone to the first organic solvent is 1 g:(5 - 10 mL).

[0028] By adopting the above technical solutions, appropriate ratios ensure an efficient quaternization reaction, enabling the full conversion of 1,7-dichloro-4-heptanone into N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride, thereby maximizing ionic conductivity and chemical stability. At the same time, controlling the solvent dosage between 5 - 10 mL / g not only ensures good dispersion and contact of the reactants but also avoids low reaction efficiency caused by excessive solvent amount or increased side reactions caused by too little solvent. To ensure the efficiency of the Menschutkin reaction, an excess of trimethylamine is required, and the optimal addition amount is 3 to 5 times in excess. Too much will cause waste of trimethylamine, and too little will easily lead to incomplete quaternization reaction, reducing the ionic conductivity of subsequent ionic polymers and anion exchange membranes. Similarly, too high a solvent ratio will dilute the reaction system, reducing the reaction rate and yield; too low a ratio may lead to poor dissolution of the reactants, causing local high concentration and generating uncontrollable side reactions, affecting the quality and consistency of the final material.

[0029] Based on the above technical solutions, preferably, in step S1, the first organic solvent is at least one of methanol, ethanol, and tetrahydrofuran.

[0030] Based on the above technical solutions, preferably, in step S1, the temperature of the Menxiu Jin reaction is 30~50 °C, and the reaction time is 24~36 h.

[0031] Based on the above technical solutions, in step S1, the temperature of the Menxiu Jin reaction independently selects any value from 30 °C, 40 °C, 50 °C or the range value between any two of the above.

[0032] Based on the above technical solutions, in step S1, the Menxiu Jin reaction independently selects any value from 24 h, 28 h, 32 h, 36 h or the range value between any two of the above.

[0033] Based on the above technical solutions, preferably, in step S1, after the reaction, the product of the Menxiu Jin reaction is removed by a rotary evaporator to obtain the product N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride.

[0034] Based on the above technical solutions, preferably, in step S2, the molar ratio of N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride to the hydroxyl-containing all-carbon flexible polymer backbone is (0.2~0.9):1; the molar ratio of aromatic aldehyde and / or aromatic ketone to the hydroxyl-containing all-carbon flexible polymer backbone is (0.2~0.8):1; the mass-volume ratio of the hydroxyl-containing all-carbon flexible polymer backbone to the second organic solvent is 1 g:(20~40 mL).

[0035] By adopting the above technical solutions, an efficient acetal and / or ketal reaction is ensured, enabling functional side chains to be uniformly and appropriately introduced into the polymer backbone, thereby achieving highly customized material properties. The appropriate molar ratio ensures the best balance between ionic conductivity and mechanical flexibility, while avoiding an increase in material rigidity or a decrease in solubility caused by excessive functionalization. In addition, an appropriate amount of aromatic aldehyde and / or aromatic ketone can enhance the conjugated system and electronic effect of the material, improving optical and electrical properties without causing unnecessary side reactions or structural instability.

[0036] Based on the above technical solutions, preferably, in step S2, the second organic solvent is dimethyl sulfoxide (DMSO).

[0037] Based on the above technical solutions, preferably, in step S2, the first catalyst includes at least one of hydrochloric acid, concentrated sulfuric acid, trifluoroacetic acid, p-trifluoromethylbenzenesulfonic acid or trifluoromethanesulfonic acid. In the present invention, the addition of the first catalyst is to adjust the pH value of the reaction solution to 3~4.

[0038] Based on the above technical solutions, preferably, in step S2, the temperature of the acetalization and / or ketalization reaction is 60-80 °C, and the polymerization reaction time is 6-24 h.

[0039] Based on the above technical solutions, in step S2, the temperature of the acetalization and / or ketalization reaction independently selects any value from 60 °C, 70 °C, 80 °C or the range value between any two of the above.

[0040] Based on the above technical solutions, in step S2, the acetalization and / or ketalization reaction independently selects any value from 6 h, 8 h, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h or the range value between any two of the above.

[0041] Based on the above technical solutions, preferably, in step S2, after the reaction, an alkali solution is used as a reaction terminator.

[0042] More preferably, the reaction terminator is selected from a 0.5 mol / L sodium carbonate solution or a 1 mol / L sodium hydroxide solution.

[0043] By adopting the above technical solutions, using a 0.5 mol / L sodium carbonate solution or a 1 mol / L sodium hydroxide solution as a reaction terminator not only helps to improve the quality, stability and purity of the final product, but also simplifies the subsequent treatment steps, reduces the operation difficulty and safety risks.

[0044] In a third aspect, the present invention relates to the application of the above ionomer based on a flexible backbone in an anion exchange membrane and a catalytic layer ionomer.

[0045] By adopting the above technical solutions, the ionomer can provide a higher ion exchange capacity, better dimensional stability and lower water swelling rate, effectively improving the selectivity and conductivity of the anion exchange membrane, reducing the membrane resistance and increasing the overall efficiency of the system. At the same time, in the catalytic layer ionomer, it promotes the uniform distribution and contact between catalyst particles, enhances the accessibility of electrode active sites, and further improves the rate and selectivity of the catalytic reaction. In addition, the multifunctional characteristics of the material also allow for customized design according to specific application scenarios, broadening its application scope in fuel cells, electrolyzers and other energy-related technologies.

[0046] In a fourth aspect, the present invention provides a method for preparing an anion exchange membrane. The method, on the basis of preparing an ionomer based on a flexible backbone, further includes: S3. Mix the ionomer based on a flexible backbone in step S2 with a third organic solvent, dry the mixture into a film, and mix the film with an alkali solution to obtain an anion exchange membrane with hydroxide anions.

[0047] Based on the above technical solutions, preferably, in step S3, the mass-volume ratio of the ion polymer based on the flexible main chain to the third organic solvent is 1 g:(20 - 50 mL).

[0048] Based on the above technical solutions, preferably, the third organic solvent is dimethyl sulfoxide.

[0049] Based on the above technical solutions, preferably, in step S3, the mixing temperature is 40 - 60°C, and the mixing time is 2 - 4 h. Herein, the purpose of mixing is dissolution.

[0050] Based on the above technical solutions, the mixing temperature is independently selected from any value of 40°C, 50°C, 60°C or the range value between any two of the above.

[0051] Based on the above technical solutions, preferably, the mixing time is independently selected from any value of 2 h, 3 h, 4 h or the range value between any two of the above.

[0052] Based on the above technical solutions, preferably, in step S3, the drying temperature is 70 - 90°C.

[0053] Based on the above technical solutions, the drying temperature is independently selected from any value of 70°C, 75°C, 80°C, 85°C, 90°C or the range value between any two of the above.

[0054] Based on the above technical solutions, preferably, the alkali solution includes NaOH and / or KOH solution, and the concentration of the alkali solution is 0.5 - 2.0 mol / L.

[0055] Based on the above technical solutions, preferably, the temperature of the alkali solution is 30 - 80°C.

[0056] Based on the above technical solutions, the temperature of the alkali solution is independently selected from any value of 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or the range value between any two of the above.

[0057] Based on the above technical solutions, preferably, the soaking time is 12 - 24 h.

[0058] Based on the above technical solutions, the soaking time is independently selected from any value of 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h or the range value between any two of the above.

[0059] On the basis of the above technical solutions, preferably, during the soaking process, the fresh alkaline solution is replaced 3 to 5 times.

[0060] In a fifth aspect, the present invention relates to an anion exchange membrane prepared by the above preparation method.

[0061] In a sixth aspect, the present invention relates to the application of the anion exchange membrane in fuel cells and water electrolysis.

[0062] The ion polymer based on a flexible main chain, its preparation method and application, the anion exchange membrane and its preparation method provided by the present invention have the following beneficial effects compared with the prior art:

[0063] (1) For the ion polymer / anion exchange membrane prepared by the present invention, since two cationic side chains are grafted to each functional site, it has the characteristics of high ion exchange capacity and high ionic conductivity. At the same time, due to the hydrophobicity and rigidity of the side chain containing a benzene ring, on the one hand, the anion exchange membrane of the present invention has the characteristic of high wet film strength, and on the other hand, it helps to induce microphase separation in the anion exchange membrane to promote the ion conduction efficiency. In addition, due to the high alkali resistance of the acetal and / or ketal structure, the high alkali resistance of the all-carbon flexible polymer main chain containing hydroxyl groups, and the high alkali resistance of the aliphatic quaternary ammonium cation, the ion polymer / anion exchange membrane of the present invention has the characteristic of high chemical stability. Compared with the benzene ring chain, the anion exchange membrane based on a flexible main chain prepared by the present invention has high antioxidant properties.

[0064] (2) The preparation methods of the ion polymer and the anion exchange membrane disclosed in the present invention have concise steps and are easy to realize large-scale production by the casting method.

[0065] (3) The ion polymer electrolyte of the present invention has good solubility, and its polymer solution can be used as an ionomer to be formulated with a catalyst and a dispersant into a catalyst ink for preparing an anion membrane or a gas diffusion electrode coated with a catalyst layer, improving the stability and durability of the device operation.

[0066] (4) The ion polymer provided by the present invention is composed of highly stable chemical structural units, so it has high alkali resistance stability and high antioxidant properties when used as a catalyst layer ionomer and for preparing an anion exchange membrane.

[0067] (5) Due to the hydrophilic-hydrophobic phase separation characteristics of the ion polymer / anion exchange membrane disclosed in the present invention, the prepared ion polymer / anion exchange membrane has the characteristic of high ionic conductivity.

[0068] (6) The anion exchange membrane provided by the present invention regulates the water absorption swelling rate of the anion exchange membrane, improves the wet film mechanical strength of the polymer, and enhances the rigidity of the membrane by adding a hydrophobic side chain containing a benzene ring.

[0069] (7) The method for preparing the ionomer / anion exchange membrane provided by the present invention can achieve the characteristic of adjustable physical and chemical properties by adjusting the grafting degree of cations and benzene-containing side chains, as well as the structure of the benzene-containing side chains.

[0070] (8) The anion exchange membrane of the present invention can be used as a separator electrolyte in devices such as fuel cells and water electrolyzers due to its high ionic conductivity, mechanical properties, and chemical stability.

[0071] (9) The anion exchange membrane of the present invention has a relatively low glass transition temperature due to the use of a hydroxyl-containing all-carbon flexible polymer main chain in the main chain. By introducing benzene ring side chains, the regulation of the glass transition temperature can be achieved, enabling the anion exchange membrane to meet the requirements of the hot pressing process conditions and further improving the operating performance of the anion exchange membrane in devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0073] Figure 1 It is the nuclear magnetic resonance hydrogen spectrum ( 1 1H NMR) diagram of the structure of N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride of the present invention;

[0074] Figure 2 It is the nuclear magnetic resonance hydrogen spectrum diagram of the anion exchange membrane in Example 1 of the present invention;

[0075] Figure 3 It is the H2-O2 single cell performance curve of the anion exchange membrane in Example 1 of the present invention at 80 °C;

[0076] Figure 4 It is the mechanical property curve diagram of the anion exchange membrane in Example 2 of the present invention in dry and wet states respectively;

[0077] Figure 5 It is the curve diagram of the ionic conductivity of the anion exchange membrane in Example 2 of the present invention varying with temperature;

[0078] Figure 6 It is the small-angle X-ray scattering (SAXS) diagram of the anion exchange membrane in Example 3 of the present invention.

[0079] Figure 7 It is for the anion exchange membrane in Example 3 of the present invention at 1 M, 80 oC histogram of ionic conductivity before and after 1440 h of immersion;

[0080] Figure 8 is a curve diagram showing the change of water content of anion exchange membrane with temperature in Example 4 of the present invention;

[0081] Figure 9 is a curve diagram showing the change of swelling rate of anion exchange membrane with temperature in Example 4 of the present invention;

[0082] Figure 10 is a linear sweep voltammetry (LSV) curve of the anion exchange membrane at 60° C. and 80° C. in Example 5 of the present invention;

[0083] Figure 11 This is a bar graph of the mass retention rate of the anion exchange membrane in Example 6 of the present invention after being immersed in Fenton's reagent for 6 hours. DETAILED DESCRIPTION

[0084] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0085] 1,7-dichloro-4-heptanone, p-fluorobenzaldehyde, 3,4,5-trifluorobenzaldehyde, 4-(trifluoromethyl)benzaldehyde, 2,2,2-trifluoroacetophenone, 4'-(trifluoromethyl)acetophenone, 2,2,2,4'-tetrafluoroacetophenone, hydrochloric acid, concentrated sulfuric acid, trifluoroacetic acid, p-trifluoromethylbenzenesulfonic acid, trifluoromethanesulfonic acid, polyvinyl alcohol PVA-P767001 (Mw = 190000, alcoholysis degree = 98-99 mol%) used in the following examples were purchased from Shanghai Maclean Biochemical Technology Co., Ltd., and the methanol solution of trimethylamine (3.2M) was purchased from Beijing Bailingwei Technology Co., Ltd. Ethylene-vinyl alcohol copolymer was purchased from Kuraray Co., Ltd., with the brand name F171B (vinyl alcohol accounts for 68%). The remaining materials not shown are all commercially available conventional products.

[0086] The test methods for the relevant test items in the following embodiments 1 to 6 are as follows:

[0087] (1) Ionic conductivity

[0088] The ionic resistance of the anion exchange membrane was measured by the AC impedance method. The measurement frequency range was 1Hz-4MHz and the potential amplitude was 5 mV. The measured resistance Nyquist curve was fitted. The intersection of the curve and the real axis Z' was the ionic resistance value of the anion exchange membrane. R。The formula for calculating conductivity is as follows:

[0089] ;

[0090] σ is the ionic conductivity, l is the distance between the two electrodes, R is the ionic resistance of the sample measured, S is the cross-sectional area of the membrane.

[0091] (2) Ion Exchange Capacity (IEC)

[0092] The test method includes: using the Mohr titration method to test the ion exchange capacity of the AEM, and the calculation formula is as follows:

[0093] ;

[0094] In the formula, c (AgNO3) is the concentration of the AgNO3 solution, v (AgNO3) is the volume of the AgNO3 solution consumed, m dry(Cl - ) is the dry weight of the AEM.

[0095] Water content

[0096] The test method includes: taking an AEM with an anion of OH - and drying the water on its surface with filter paper, then weighing it in a saturated water-containing state , then placing the membrane in a vacuum drying oven at 65 °C and drying it for 12 hours until the mass of the membrane no longer decreases, and then weighing it , and the formula for calculating the water content is as follows:

[0097] .

[0098] (4) Mechanical strength: The mechanical property test includes the tensile strength and elongation at break of the anion exchange membrane in a fully wet state for the sample to be tested, and the running speed of the instrument for stretching is 5 mm / min.

[0099] (5) Alkaline stability

[0100] The test conditions are: soaking in a 1 mol / L KOH solution at 80 °C for 1440 hours. The retention rate of ionic conductivity is used as the measurement standard.

[0101] Planar swelling ratio (SD)

[0102] The test method includes: first recording the planar dimensions of the dry membrane , then the counter ion is OH - The planar dimensions of the AEM with - after being fully swollen by absorbing water at different temperatures are measured and recorded as . The formula for calculating the planar dimension stability is as follows:

[0103] .

[0104] Antioxidant stability

[0105] The test conditions include: soaking the ion exchange membrane prepared in this example in Fenton's reagent at 40 °C for 168 h. The ratio of Fenton's reagent is 3 wt% hydrogen peroxide and 4 ppm ferrous ions.

[0106] Perform fuel cell performance tests

[0107] The fuel cell operating temperature is 80 °C, the gas flow rates of H2 and O2 are both 500 sccm, and the gas is 100% humidified. Platinum supported on carbon is used as the catalyst for both the cathode and anode in the membrane electrode, and the catalyst loading is 0.4 mg / cm 2 . The ionomer prepared in the example is used as the catalytic layer ionomer. The anion exchange membrane prepared in the example is used as the electrolyte diaphragm in the fuel cell device.

[0108] Water electrolysis performance in a zero-gap electrolyzer

[0109] The cathode uses a Pt / C catalyst, the anode uses a NiFe2O4 catalyst, the membrane electrode ionomer uses the ionomer prepared in this example, and the anion exchange membrane prepared in the example is used as the electrolyte diaphragm in the water electrolyzer. The electrolyte solution in the electrolyzer is 1 M KOH solution. The LSV scan rate is 10 mV / s, and the scan range is 1.2 - 2.0 V.

[0110] Example 1

[0111] This example provides an ionomer and an anion exchange membrane based on a flexible main chain, which are prepared by the following method:

[0112] (1) In a 250 mL single-neck round-bottom flask, 4.9 g of 1,7-dichloro-4-heptanone and 68 mL of trimethylamine methanol solution are added to 25 mL of methanol, and the mixture is magnetically stirred and reacted at 40 °C for 36 h under sealed conditions. After the reaction is completed, the methanol solvent and excess unreacted trimethylamine are removed on a rotary evaporator until a yellow oily viscous liquid is obtained. This liquid is the product after quaternization of 1,7-dichloro-4-heptanone, N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride, and its nuclear magnetic resonance hydrogen spectrum is as Figure 1 shown.

[0113] (2) In a 100 mL two-necked round-bottom flask, 2 g of PVA was dissolved in 40 mL of DMSO at 80 °C. After it was completely dissolved and cooled to room temperature, the synthesized N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride, 6.3 g of 4-(trifluoromethyl)benzaldehyde and 1.2 mL of trifluoroacetic acid were added. The temperature was raised to 60 °C and the reaction was continuously stirred for 12 h. After the reaction was completed, the reaction solution was added dropwise to a 0.5 M Na2CO3 aqueous solution to obtain an orange crude product. The crude product was crushed with a blender, washed with a large amount of deionized water until neutral, and finally dried in a vacuum drying oven at 60 °C for 24 h to obtain a quaternized acetal and ketalized polymer with chloride ions as anions and 4-(trifluoromethyl)phenyl as the hydrophobic side chain. Its specific structure is as follows:

[0114]

[0115] (3) In a 50 mL two-necked round-bottom flask, 0.4 g of the polymer electrolyte with chloride ions as anions and 4-(trifluoromethyl)phenyl as the hydrophobic side chain was added to 15 mL of DMSO solvent. After stirring at 60 °C for 3 h until it was completely dissolved, the solution was cast on a flat and clean glass plate with a size of 8 cm × 8 cm, and then placed in an electric heating oven at 80 °C. An anion exchange membrane with a thickness of about 45 μm was obtained by solvent evaporation. Finally, the chloride ion type anion exchange membrane was soaked in a 1 mol / L potassium hydroxide solution at 60 °C for 12 hours, and the fresh alkali solution was replaced 3 times during this period. Finally, the residual floating alkali on the membrane surface was rinsed with deionized water until the pH of the aqueous solution was 7, and an anion exchange membrane with hydroxide ions as anions was obtained. Its 1H NMR spectrum is as Figure 2 shown. The anion exchange membrane was stored in deionized water with nitrogen passing through. Its specific structure is as follows:

[0116]

[0117] Among them, x is 0.1, y is 0.2, z is 0.4, and t is 0.

[0118] The IEC of the anion exchange membrane prepared in this example was 1.75 mmol·g -1 ; the ionic conductivity at 80 °C was 135.5 mS·cm -1 , the water content was 50.2%, and the swelling ratio was 9.3%; in the dry state, the tensile strength was 75.2 MPa, and the elongation at break was 23.5%; after the antioxidant stability test, the mass retention rate was 96.6%; after the alkali resistance stability test, the retention rate of ionic conductivity was 92.1%.

[0119] The test results of the ionomer prepared based on this embodiment as the catalyst layer ionomer are as follows Figure 3 shown. From Figure 3 the results, it can be seen that for the fuel cell assembled with the ionomer and the anion exchange membrane prepared based on this embodiment, the open-circuit voltage of the battery is 1.02 V, and the maximum power density is 825.0 mW / cm 2 , which proves the good applicability of the ionomer and the anion exchange membrane in Example 1 in the field of fuel cells.

[0120] Example 2

[0121] This embodiment provides an ionomer and an anion exchange membrane based on a flexible main chain, which are prepared by the following method:

[0122] (1) In a 250 mL single-necked round-bottom flask, 5.6 g of 1,7-dichloro-4-heptanone and 78 mL of trimethylamine methanol solution are added to 30 mL of methanol, and the reaction is magnetically stirred at 40 °C for 36 h under sealed conditions. After the reaction is completed, the methanol solvent and the excess unreacted trimethylamine are removed on a rotary evaporator until a yellow oily viscous liquid is obtained. This liquid is the product after the quaternization of 1,7-dichloro-4-heptanone, N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride.

[0123] (2) In a 100 mL two-necked round-bottom flask, 2 g of EVOH is dissolved in 40 mL of DMSO at 80 °C. After it is completely dissolved and cooled to room temperature, the above-synthesized N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride, 5.10 g of p-fluorobenzaldehyde and 1.5 mL of concentrated hydrochloric acid are added, and the temperature is raised to 80 °C and the reaction is continuously stirred for 6 h. After the reaction is completed, the reaction solution is added dropwise to a 0.5 M Na2CO3 aqueous solution to obtain an orange crude product. The crude product is crushed with a blender, washed with a large amount of deionized water until neutral, and finally dried in a vacuum drying oven at 60 °C for 24 h to obtain a quaternized acetal and ketalized polymer with chloride ions as anions and p-fluorophenyl as the hydrophobic side chain. Its specific structure is as follows:

[0124]

[0125] (3) In a 50 mL two-necked round-bottom flask, 0.4 g of the above-mentioned polymer electrolyte with chloride ions as anions and p-fluorophenyl as the hydrophobic side chain was added to 15 mL of DMSO solvent. After stirring at 60 °C for 3 h until it was completely dissolved, the solution was cast on a flat and clean glass plate of 8 cm × 8 cm, and then placed in an 80 °C electric heating oven. An anion exchange membrane with a thickness of about 45 μm was obtained by solvent evaporation. Finally, the chloride ion type anion exchange membrane was soaked in a 1 mol / L potassium hydroxide solution at 60 °C for 12 hours, and the fresh alkali solution was replaced 3 times during this period. Finally, the residual floating alkali on the membrane surface was rinsed with deionized water until the pH of the aqueous solution was 7, and the anion exchange membrane with hydroxide ions as anions was obtained. The anion exchange membrane was stored in deionized water purged with nitrogen. Its specific structure is as follows:

[0126]

[0127] Among them, x is 0.1, y is 0.2, z is 0.08, and t is 0.32.

[0128] The ion exchange capacity (IEC) of the anion exchange membrane prepared in this example was 1.72 mmol·g -1 ; the water content at 80 °C was 37.2%, and the swelling ratio was 4.5%; the mass retention rate after the antioxidant stability test was 95.8%; the retention rate of the ionic conductivity after the alkali resistance stability test was 92.9%.

[0129] The mechanical property test results of the anion exchange membrane prepared in this example are as Figure 4 shown. From Figure 4 the results, it can be seen that the anion exchange membrane prepared in this example has a tensile strength higher than 80 MPa and an elongation at break greater than 25% under dry conditions. The tensile strength of the wet membrane is higher than 35 MPa and the elongation at break is higher than 300% in the fully wet state. This mechanical property can support the use of the anion exchange membrane as a separator material in electrochemical devices.

[0130] The ionic conductivity test results of the anion exchange prepared in this example are as Figure 5 shown. From Figure 5 the results, it can be seen that the anion exchange membrane prepared in Example 2 has an ionic conductivity of 125.6 mS·cm o at 80 -1 , meeting the conditions for efficiently conducting charges as a polymer electrolyte in electrochemical devices.

[0131] Example 3

[0132] This example provides an ion polymer and an anion exchange membrane based on a flexible main chain, which are prepared by the following method:

[0133] (1) In a 250 mL single-necked round-bottom flask, 5.6 g of 1,7-dichloro-4-heptanone and 78 mL of trimethylamine methanol solution were added to 30 mL of methanol, and the reaction was magnetically stirred at 40 °C for 36 h under sealed conditions. After the reaction was completed, the methanol solvent and the excess unreacted trimethylamine were removed on a rotary evaporator until a yellow oily viscous liquid was obtained. This liquid was the product after the quaternization of 1,7-dichloro-4-heptanone, N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride.

[0134] (2) In a 100 mL two-necked round-bottom flask, 2 g of EVOH was dissolved in 40 mL of DMSO at 80 °C. After it was completely dissolved and cooled to room temperature, the above-synthesized N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride, 3.3 g of 3,4,5-trifluorobenzaldehyde and 1.8 mL of trifluoroacetic acid were added. The temperature was raised to 60 °C and the reaction was continuously stirred for 10 h. After the reaction was completed, the reaction solution was slowly added dropwise to 0.5 M Na2CO3 aqueous solution to obtain an orange crude product. The crude product was crushed with a blender, washed with a large amount of deionized water until neutral, and finally dried in a vacuum drying oven at 60 °C for 24 h to obtain a quaternized acetal and ketalized polymer with chloride ions as anions and 3,4,5-trifluorophenyl as the hydrophobic side chain. Its specific structure is as follows:

[0135]

[0136] (3) In a 50 mL two-necked round-bottom flask, 0.4 g of the above polymer electrolyte with chloride ions as anions and 3,4,5-trifluorophenyl as the hydrophobic side chain was added to 15 mL of DMSO solvent. After stirring at 60 °C for 4 h until it was completely dissolved, the solution was cast on a flat and clean glass plate with a size of 8 cm × 8 cm, and then placed in an electric heating oven at 80 °C. A chloride ion type anion exchange membrane with a thickness of about 45 μm was obtained by solvent evaporation. Finally, the chloride ion type anion exchange membrane was soaked in 1 mol / L potassium hydroxide solution at 60 °C for 12 hours, and the fresh alkali solution was replaced 3 times during this period. Finally, the residual floating alkali on the membrane surface was rinsed with deionized water until the pH of the aqueous solution was 7, and the anion exchange membrane with hydroxide ions as anions was obtained. The anion exchange membrane was stored in deionized water with nitrogen passing through. Its specific structure is as follows:

[0137]

[0138] Among them, x is 0.1, y is 0.1, z is 0.28, and t is 0.32.

[0139] The IEC of the anion exchange membrane prepared in this example of the test is 1.97 mmol·g -1 ; the ionic conductivity at 80 °C is 131.2 mS·cm -1 , the water content is 45.2%, and the swelling ratio is 7.5%; in the dry state, the tensile strength is 68.4 MPa, and the elongation at break is 33.8%; after the antioxidant stability test, the mass retention rate is 97.6%; after the alkali resistance stability test, the retention rate of ionic conductivity is 93.3%.

[0140] The small-angle X-ray scattering test was performed on the anion exchange membrane prepared in this example using Anton Paar SAXSess mc2 from Austria, and the test results are as Figure 6 shown. From Figure 6 the results, it can be seen that the anion exchange membrane prepared in this example has a long-range ordered microstructure. The main chain is grafted with hydrophilic ionic component side chains and hydrophobic side chains at the same time, which helps the anion exchange membrane to form a hydrophilic-hydrophobic microphase separation, thereby promoting rapid ion conduction.

[0141] The results of the alkali resistance stability test of the anion exchange membrane prepared in this example are as Figure 7 shown. From Figure 7 the results, it can be seen that the ionic conductivity of the anion exchange membrane prepared in this example at 80 °C before the above alkali resistance stability test is 131.2 mS / cm, and after the test, the ionic conductivity at 80 °C is 122.4 mS / cm, and the loss rate of ionic conductivity is 6.7%, which is less than 10%, proving that it has good alkali resistance stability.

[0142] Example 4

[0143] This example provides an ion polymer and an anion exchange membrane based on a flexible main chain, which are prepared by the following method:

[0144] (1) In a 150 mL single-necked round-bottom flask, 4.9 g of 1,7-dichloro-4-heptanone and 68 mL of trimethylamine methanol solution were added to 20 mL of methanol, and the reaction was magnetically stirred at 40 °C for 36 h under sealed conditions. After the reaction, the methanol solvent and the excess unreacted trimethylamine were removed on a rotary evaporator until a yellow oily viscous liquid was obtained. This liquid is the product after the quaternization of 1,7-dichloro-4-heptanone, N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride.

[0145] (2) In a 100 mL two-necked round-bottom flask, 2 g of PVA was dissolved in 40 mL of DMSO at 80 °C. After it was completely dissolved and cooled to room temperature, the synthesized N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride, 6.8 g of 4'-(trifluoromethyl)acetophenone and 2.5 mL of trifluoromethanesulfonic acid were added. The temperature was raised to 80 °C and the reaction was stirred continuously for 24 h. After the reaction was completed, the reaction solution was added dropwise to 0.5 M aqueous Na2CO3 solution to obtain an orange crude product. The crude product was crushed with a blender, washed with a large amount of deionized water until neutral, and finally dried in a vacuum drying oven at 60 °C for 24 h to obtain a quaternized ketalized polymer with chloride ions as anions and 4'-(trifluoromethyl)phenylacetyl as the hydrophobic side chain. Its specific structure is as follows:

[0146]

[0147] (3) In a 50 mL two-necked round-bottom flask, 0.4 g of the polymer electrolyte with chloride ions as anions and 4'-(trifluoromethyl)phenylacetyl as the hydrophobic side chain was added to 15 mL of DMSO solvent. After stirring at 60 °C for 3 h until it was completely dissolved, the solution was cast on a flat and clean glass plate of 8 cm × 8 cm, and then placed in an electric heating oven at 80 °C. A chloride ion type anion exchange membrane with a thickness of about 45 μm was obtained by solvent evaporation. Finally, the chloride ion type anion exchange membrane was soaked in 1 mol / L potassium hydroxide solution at 60 °C for 12 hours, and the fresh alkali solution was replaced 3 times during this period. Finally, the residual floating alkali on the membrane surface was rinsed with deionized water until the pH of the aqueous solution was 7, and the anion exchange membrane with hydroxide ions as anions was obtained. The anion exchange membrane was stored in deionized water with nitrogen passing through. Its specific structure is as follows:

[0148]

[0149] Among them, x is 0.1, y is 0.2, z is 0.4, and t is 0.

[0150] The IEC of the anion exchange membrane prepared in this example was 1.45 mmol·g -1 ; the ionic conductivity at 80 °C was 115.1 mS·cm -1 , the water content was 42.5%, and the swelling ratio was 7.9%; in the dry state, the tensile strength was 42.8 MPa, and the elongation at break was 15.3%; after the antioxidant stability test, the mass retention rate was 92.4%; after the alkali resistance stability test, the retention rate of ionic conductivity was 90.0%.

[0151] The water content test results of the anion exchange prepared in this example are as Figure 8 shown. FromFigure 8 As can be seen from the results, the water content of the anion exchange membrane prepared in this example is 42.5% at 80 °C.

[0152] The test results of the planar swelling ratio of the anion exchange membrane prepared in this example are as Figure 9 shown. From Figure 9 the results, it can be seen that the planar swelling ratio of the anion exchange membrane prepared in this example is 7.9% at 80 °C, showing high wet membrane planar dimensional stability.

[0153] Example 5

[0154] This example provides an ion polymer and an anion exchange membrane based on a flexible main chain, which are prepared by the following method:

[0155] (1) In a 250 mL single-necked round-bottom flask, 7.37 g of 1,7-dichloro-4-heptanone and 101.2 mL of trimethylamine methanol solution were added to 40 mL of methanol, and the mixture was magnetically stirred at 40 °C for 36 h under sealed conditions. After the reaction was completed, the methanol solvent and the excess unreacted trimethylamine were removed on a rotary evaporator until a yellow oily viscous liquid was obtained. This liquid is the product after the quaternization of 1,7-dichloro-4-heptanone, N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride.

[0156] (2) In a 100 mL two-necked round-bottom flask, 2 g of PVA was dissolved in 40 mL of DMSO at 80 °C. After it was completely dissolved and cooled to room temperature, the above-synthesized N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride, 8.7 g of 2,2,2,4'-tetrafluorobenzophenone, and 1.5 mL of p-trifluoromethylbenzenesulfonic acid were added. The temperature was raised to 80 °C and the reaction was continuously stirred for 12 h. After the reaction was completed, the reaction solution was slowly added dropwise to a 0.5 M Na2CO3 aqueous solution to obtain an orange crude product. The crude product was pulverized with a blender, washed with a large amount of deionized water until neutral, and finally dried in a vacuum drying oven at 60 °C for 24 h to obtain a quaternized ketalized polymer with chloride ions as anions and 2,2,2,4'-tetrafluorobenzophenone groups as hydrophobic side chains. Its specific structure is as follows:

[0157]

[0158] (3) In a 50 mL two-necked round-bottom flask, 0.4 g of the above polymer electrolyte with chloride ions as anions and 2,2,2,4'-tetrafluorophenacyl groups as hydrophobic side chains was added to 15 mL of DMSO solvent. After stirring at 60 °C for 4 h until it was completely dissolved, the solution was cast on a flat and clean glass plate with a size of 8 cm × 8 cm, and then placed in an electric heating oven at 80 °C. A chloride ion-based anion exchange membrane with a thickness of about 45 μm was obtained by solvent evaporation. Finally, the chloride ion-based anion exchange membrane was soaked in a 1 mol / L potassium hydroxide solution at 60 °C for 12 hours, during which the fresh alkali solution was replaced 3 times. Finally, the residual floating alkali on the membrane surface was rinsed with deionized water until the pH of the aqueous solution was 7, and the anion exchange membrane with hydroxide ions as anions was obtained. The anion exchange membrane was stored in deionized water purged with nitrogen. Its specific structure is as follows:

[0159]

[0160] Among them, x is 0.15, y is 0.2, z is 0.3, and t is 0.

[0161] The IEC of the anion exchange membrane prepared in this example was 2.01 mmol·g -1 ; the ionic conductivity at 80 °C was 128.8 mS·cm -1 , the water content was 32.2%, and the swelling ratio was 5.6%; in the dry state, the tensile strength was 55.6 MPa, and the elongation at break was 19.9%; after the antioxidant stability test, the mass retention rate was 97.4%; after the alkali resistance stability test, the retention rate of ionic conductivity was 96.8%.

[0162] The test results of the water electrolysis performance of the anion exchange membrane prepared based on this example in a zero-gap electrolytic cell are as shown in the appendix Figure 10 shown. From Figure 10 it can be seen that at 80 °C, when the current density is 1.0 A·cm -2 , the corresponding voltage is 1.82 V, and at 60 °C, when the current density is 1.0 A·cm -2 , the corresponding voltage is 1.87 V.

[0163] Example 6

[0164] This example provides an ion polymer and an anion exchange membrane based on a flexible main chain, which are prepared by the following method:

[0165] (1) In a 150 mL single-necked round-bottom flask, 4.9 g of 1,7-dichloro-4-heptanone and 68 mL of trimethylamine methanol solution were added to 25 mL of methanol, and the mixture was magnetically stirred at 40 °C for 36 h under sealed conditions. After the reaction, the methanol solvent and the excess unreacted trimethylamine were removed on a rotary evaporator until a yellow oily viscous liquid was obtained. This liquid is the product after the quaternization of 1,7-dichloro-4-heptanone, N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride.

[0166] (2) In a 100 mL two-necked round-bottom flask, 2 g of PVA was dissolved in 40 mL of DMSO at 80 °C. After it was completely dissolved and cooled to room temperature, the synthesized N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride, 6.3 g of 2,2,2-trifluoroacetophenone and 1.8 mL of trifluoroacetic acid were added. The temperature was raised to 60 °C and the reaction was continuously stirred for 24 h. After the reaction, the reaction solution was added dropwise to 0.5 M Na2CO3 aqueous solution to obtain an orange crude product. The crude product was pulverized with a blender, washed with a large amount of deionized water until neutral, and finally dried in a vacuum drying oven at 60 °C for 24 h to obtain a quaternized ketalized polymer with chloride ions as anions and 2,2,2-trifluoroacetophenone groups as hydrophobic side chains. Its specific structure is as follows:

[0167]

[0168] (3) In a 50 mL two-necked round-bottom flask, 0.4 g of the polymer electrolyte with chloride ions as anions and 2,2,2-trifluoroacetophenone groups as hydrophobic side chains was added to 15 mL of DMSO solvent, and the mixture was stirred at 60 °C for 3 h until it was completely dissolved. Then the solution was cast on a flat and clean glass plate with a size of 8 cm × 8 cm, and then placed in an electric heating oven at 80 °C. A chloride ion type anion exchange membrane with a thickness of about 45 μm was obtained by solvent evaporation. Finally, the chloride ion type anion exchange membrane was soaked in 1 mol / L potassium hydroxide solution at 60 °C for 12 hours, and the fresh alkali solution was replaced 3 times during this period. Finally, the residual floating alkali on the membrane surface was rinsed with deionized water until the pH of the aqueous solution was 7, and the anion exchange membrane with hydroxide ions as anions was obtained. The anion exchange membrane was stored in deionized water with nitrogen passing through. Its specific structure is as follows:

[0169]

[0170] Among them, x is 0.1, y is 0.2, z is 0.4, and t is 0.

[0171] The IEC of the anion exchange membrane prepared in this example tested was 1.73 mmol·g-1 ; The ionic conductivity at 80 °C is 131.1 mS·cm -1 , the water content is 46.2%, and the swelling ratio is 8.8%; in the dry state, the tensile strength is 70.2 MPa and the elongation at break is 13.5%; after the alkali resistance stability test, the retention rate of the ionic conductivity is 95.6%.

[0172] The results of the antioxidant stability test of the anion exchange membrane prepared in this example are as Figure 11 shown. From Figure 11 the results, it can be seen that after being immersed in Fenton's reagent at 40 °C for 168 hours in the example of the present invention, the mass retention rate is 98.1%.

[0173] Comparative example (Int J Hydrogen Energ. 46, 2021, 37007—37016)

[0174] In the comparative example, polyvinyl alcohol was used as the polymer main chain. In order to increase the strength of the prepared anion exchange membrane, brominated polyphenylene ether was introduced, and 4-imidazole benzaldehyde was used as the cross-linking agent. On the one hand, 4-imidazole benzaldehyde undergoes an aldol condensation reaction with the hydroxyl groups on polyvinyl alcohol. On the other hand, 4-imidazole benzaldehyde undergoes a Menshutkin reaction with brominated polyphenylene ether to generate cations while realizing the cross-linking of two different polymers. The optimal test example c-91 was selected as the comparative example of the present invention.

[0175] The optimized comparative example c-91 has a fuel cell performance of 105 mW·cm o at 60 -2 .

[0176] The optimized comparative example c-91 has a tensile strength of 47.0 MPa and an elongation at break of less than 10%.

[0177] The optimized comparative example c-91 has an ionic conductivity of 78.8 mS·cm -1 at 80 °C, a swelling ratio of 14%, and a water content of less than 55%.

[0178] The SAXS results of the optimized comparative example c-91 show that it has an absorption peak at q = 0.28 nm -1 .

[0179] After the optimized comparative example c-91 is immersed in Fenton's reagent at 40 o °C for 168 h, the mass retention rate is 69.7%.

[0180] After the optimized comparative example c-91 is immersed in 1 M NaOH solution at 80 °C for 1000 h, the retention rate of the ionic conductivity is 75%.

[0181] Table 1 shows the summary of partial test data results of the anion exchange membranes prepared in the above Examples 1 to 6 and the optimized Comparative Example c-91, as follows:

[0182] Among them, the test conditions for ionic conductivity, swelling ratio, water content, SAXS, mechanical properties, and antioxidant stability of the comparative examples and examples are the same. The test condition for alkali resistance stability in the examples of this patent is soaking in a 1 mol / L KOH solution at 80 °C for 1440 hours. The test temperature for fuel cell performance in the examples of this patent is 80 o °C.

[0183] Table 1 Comparison Table of Test Results

[0184]

[0185] It can be seen from the performance data in Table 1 above that: compared with the comparative examples, the anion exchange membranes based on flexible backbones prepared in Examples 1 to 6 of the present invention have the characteristics of excellent mechanical properties, high ionic conductivity, low swelling ratio, high antioxidant stability, high alkali resistance stability, and high fuel cell performance.

[0186] The ion polymers and anion exchange membranes based on flexible backbones prepared in Examples 1 to 6 of the present invention are all composed of a hydroxyl-containing all-carbon flexible polymer backbone, fluorine-containing side chains, and alkyl cations, and have a soluble ionomer. Due to the high molecular weight of the backbone in the examples, the prepared anion exchange membranes have more excellent mechanical properties. Since the SAXS scattering peaks in the examples are higher, the distance d between the corresponding ion clusters is smaller, which is more conducive to the formation of continuous and wide ion channels by the ion clusters, promoting rapid ion conduction, and the examples have a higher ion exchange capacity, so the examples have a higher hydroxide ion conductivity. Since the examples do not contain unstable polymer backbones such as polyphenylene ether, the examples have more remarkable antioxidant stability and alkali resistance stability compared with the comparative examples. When preparing the membrane electrode, the examples have the corresponding ion polymer as the ionomer for the anion exchange membrane, and since the anion exchange membrane has a higher ionic conductivity, the examples show better single-cell discharge performance.

[0187] In summary, the anion exchange membrane based on a flexible backbone prepared by the present invention has high ionic conductivity, high chemical stability, and high mechanical properties, and can be used as a separator material for conducting ions in electrochemical devices, such as electrochemical devices like water electrolysis and fuel cells. The ion polymer based on a flexible backbone prepared by the present invention has good solubility, and the polymer solution can be used as an ionomer together with a catalyst and a dispersant to prepare a catalyst ink for preparing a membrane electrode, which can improve the operating performance of the device.

[0188] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An ionic polymer based on a flexible main chain, characterized in that: The polymer is represented by formula (I): （Ⅰ）； In formula (I), x, y, z, and t all represent the molar proportion of each structural unit in the ionic polymer; wherein the value range of 2x+2y is 0.4~1.0, and 2x+2y+z+t=1.0; R includes at least one benzene ring; the value range of x is 0.1~0.5, and the value range of y is 0.1~0.

5.

2. The ionic polymer based on a flexible main chain according to claim 1, characterized in that The value range of x is 0.1~0.5, the value range of y is 0.1~0.5, the value range of z is 0~0.6, and the value range of t is 0~0.

4.

3. A method for preparing an ionic polymer based on a flexible main chain as described in claim 1 or 2, wherein the ionic polymer based on a flexible main chain is prepared by acetalization and / or ketalization of a full-carbon flexible polymer main chain, an aldehyde or ketone and a quaternization product of 1,7-dichloro-4-heptanone.

4. The method for preparing an ionic polymer based on a flexible main chain according to claim 3, characterized in that: The all-carbon flexible polymer main chain is a hydroxyl-containing all-carbon flexible polymer main chain; the aldehyde or ketone is an aromatic aldehyde or aromatic ketone; The aromatic aldehyde is selected from at least one of p-fluorobenzaldehyde, 3,5-difluorobenzaldehyde, 3,4,5-trifluorobenzaldehyde, 2,3,4,5,6-pentafluorobenzaldehyde, 4-(trifluoromethyl)benzaldehyde, p-methylbenzaldehyde, benzaldehyde, m-methylbenzaldehyde or 3-(4-fluorophenyl)benzaldehyde, and / or the aromatic ketone is selected from at least one of 2,2,2,-trifluoroacetophenone, 4'-(trifluoromethyl)acetophenone or 2,2,2,4'-tetrafluoroacetophenone.

5. The method for preparing an ionic polymer based on a flexible main chain according to claim 4, characterized in that: The method comprises the following steps: S1. Mix 1,7-dichloro-4-heptanone and trimethylamine solution in a first organic solvent to obtain N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride; S2, a hydroxyl-containing all-carbon flexible polymer main chain, the N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride obtained in step S1 and aromatic aldehydes and / or aromatic ketones are mixed in the presence of a second organic solvent and a catalyst to obtain an ionic polymer based on a flexible main chain.

6. The method for preparing an ionic polymer based on a flexible main chain according to claim 5, characterized in that: In step S1, the amount of trimethylamine added is 3 to 5 times the molar amount of chlorine atoms in the 1,7-dichloro-4-heptanone; the mass volume ratio of the 1,7-dichloro-4-heptanone to the first organic solvent is 1 g: (5 to 10 mL); In step S2, the molar ratio of the N1,N1,N1,N7,N7,N7-hexamethyl-4-oxoheptane-1,7-diammonium chloride to the hydroxyl-containing all-carbon flexible polymer main chain is (0.2~0.9):1; the molar ratio of the aromatic aldehyde and / or aromatic ketone to the hydroxyl-containing all-carbon flexible polymer main chain is (0.2~0.8):1; the mass volume ratio of the hydroxyl-containing all-carbon flexible polymer main chain to the second organic solvent is 1g:(20~40 mL).

7. Use of the flexible main chain-based ionomer as claimed in claim 1 or 2 in anion exchange membranes and catalyst layer ionomers.

8. A method for preparing an anion exchange membrane, characterized in that: The anion exchange membrane is prepared from the ionic polymer based on a flexible main chain according to claim 1 or 2, or the anion exchange membrane is further prepared from the ionic polymer based on a flexible main chain prepared by the method according to any one of claims 3 to 6; the preparation method of the anion exchange membrane comprises the following steps: S3, mixing the ionic polymer based on the flexible main chain with the third organic solvent, drying the mixed solution to form a membrane, and immersing the membrane in an alkaline solution to obtain an anion exchange membrane whose anion is hydroxide; The mass volume ratio of the flexible main chain-based ionic polymer to the third organic solvent is 1 g: (20-50 mL).

9. An anion exchange membrane, characterized in that The anion exchange membrane is prepared by the method according to claim 8.

10. Use of the anion exchange membrane as claimed in claim 9 in fuel cells and water electrolysis.

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