Perfluorosulfonamide resin, preparation method thereof and anion exchange membrane

Abstract

The invention belongs to the technical field of ion exchange membranes, and particularly relates to perfluorosulfonamide resin, a preparation method thereof and an anion exchange membrane. The perfluorinated sulfonic acid resin is used for constructing a main chain structure, the bond energy of a C-F bond is high, and the material is endowed with intrinsic chemical inertness. And a rigid azacyclo quaternary ammonium salt cation group is introduced and directly anchored on a main chain through a sulfonamide bond. The nitrogen heterocyclic ring with a rigid structure generates remarkable steric hindrance, OH <-> ions are greatly prevented from approaching the center of quaternary ammonium salt and initiating Hofmann elimination reaction, and the problem that traditional quaternary ammonium salt is easy to degrade in strong alkali is solved. Meanwhile, effective microphase separation can be carried out between the hydrophobicity of the perfluoro main chain and the hydrophilic group of the azacyclo quaternary ammonium salt, and hydrophilic ion cluster channels which are communicated with one another are formed through self-assembly. The continuous ion transmission network is combined with the high ion exchange capacity of quaternary ammonium salt groups, so that efficient conduction of hydroxyl ions in the membrane is ensured, and high ionic conductivity is obtained.

Description

Technical Field

[0001] This invention belongs to the field of ion exchange membrane technology, specifically relating to a perfluorosulfonamide resin, its preparation method, and an anion exchange membrane. Background Technology

[0002] With the energy structure shifting towards green and low-carbon development, hydrogen energy has emerged as one of the most promising clean energy sources due to its zero emissions, high energy density, and storability. However, the large-scale application of hydrogen energy still faces challenges such as hydrogen production efficiency and cost control. Among these challenges, anion exchange membranes are core components of fuel cells and water electrolysis hydrogen production devices, and their performance directly affects the commercialization process of hydrogen energy technology.

[0003] In alkaline water electrolysis hydrogen production units, anion exchange membranes, as the core ion conductors and separators, have a decisive impact on hydrogen production efficiency, gas purity, and system stability. While an alkaline environment can reduce corrosion, improve reaction kinetics, and allow the use of non-precious metal catalysts, it places more stringent requirements on the membrane's alkaline stability. An ideal anion exchange membrane needs to achieve both high ionic conductivity and excellent chemical stability under long-term high-alkalinity operation. However, these two are often contradictory; improving conductivity is often accompanied by increased swelling and decreased structural stability, becoming a key bottleneck restricting its large-scale application.

[0004] Perfluorosulfonic acid resins, due to their perfluorocarbon chain structure, possess excellent chemical stability and mechanical properties, making them ideal materials for constructing high-performance anion exchange membrane backbones. Existing technologies have reported the formation of anion polymers with side-chain structures by grafting linear or monocyclic quaternary ammonium salt monomers containing epoxy groups onto the nitrogen atoms of perfluorosulfonamides. While the anion polymers prepared by this method can construct ion transport channels and improve conductivity, the chemical structure of their cationic groups poses a risk of degradation under strongly alkaline environments, resulting in insufficient long-term alkali resistance of the anion exchange membrane. Summary of the Invention

[0005] To address the technical problem of insufficient long-term alkali resistance in existing polymer anion exchange membranes due to the risk of degradation of cationic groups under strong alkaline environments, this invention provides a perfluorosulfonamide resin, its preparation method, and an anion exchange membrane. This invention uses a perfluorosulfonate resin to construct the main chain structure. By introducing nitrogen-containing heterocyclic quaternary ammonium salt cationic groups onto the main chain, the rigid structure of the nitrogen heterocycle generates significant steric hindrance, greatly hindering the exchange of OH groups. - The ions approach the quaternary ammonium salt center and initiate the Hoffmann elimination reaction, which significantly improves the alkali resistance of the material.

[0006] This invention introduces sulfonamide bonds directly onto a nitrogen-containing heterocyclic quaternary ammonium salt cation group within a perfluorinated backbone. The high bond energy of the perfluorinated backbone provides the basis for its chemical and mechanical stability; the sulfonamide bond, as a linking group, has high bond energy and is not easily broken under alkaline conditions; simultaneously, the quaternary ammonium salt nitrogen cation (N...) located on the nitrogen heterocycle... + Due to the steric hindrance effect and low ring strain of its ring structure, it effectively suppresses the Hoffmann elimination reaction and nucleophilic substitution reaction caused by hydroxide ion attack, thereby significantly improving the material's alkali resistance. The microphase separation between the perfluorinated hydrophobic backbone and the hydrophilic nitrogen-containing quaternary ammonium salt groups also helps to construct continuous ion transport channels, ensuring high ionic conductivity.

[0007] A perfluorosulfonamide resin, wherein the chemical structural formula of the perfluorosulfonamide resin is as follows: ; In the formula, x is an integer between 1 and 3, y is an integer between 1 and 3, and m:n = 3 to 5:1; R is selected from one of the following structures: .

[0008] A second objective of this invention is to provide a method for preparing a perfluorosulfonamide resin, comprising the following steps: Perfluorosulfonic acid resin is dissolved in an acyl chloride reagent to carry out an acyl chloride reaction, thereby obtaining perfluorosulfonyl chloride resin; perfluorosulfonyl chloride resin, amine derivatives containing nitrogen heterocycles and a first solvent are subjected to an amidation reaction under the action of a catalyst to obtain perfluorosulfonamide resin.

[0009] Preferably, the amine derivative containing a nitrogen heterocycle is N-(2-aminoethyl)morpholine, (S)-3-aminoquinine cyclic amine dihydrochloride, 1-(2-aminoethyl)pyrrolidine, or 4-amino-1-methylpiperidine.

[0010] Preferably, the ratio of perfluorosulfonyl chloride resin, nitrogen-containing heterocyclic amine derivative, and catalyst is 1g:1g-2g:0.5mL-1mL.

[0011] Preferably, the ratio of perfluorosulfonyl chloride resin to the first solvent is 1g:8mL to 15mL.

[0012] Preferably, the amidation reaction is carried out at a temperature of 60°C to 80°C for 24 to 48 hours.

[0013] Preferably, the catalyst is pyridine or N,N-dimethyl-4-aminopyridine.

[0014] Preferably, the solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide, and N-methylpyrrolidone.

[0015] Preferably, the mass ratio of perfluorosulfonic acid resin to acyl chloride reagent is 1:12 to 50.

[0016] Preferably, the temperature of the acyl chloride reaction is 90℃~100℃ and the time is 8h~12h; the temperature of the amidation reaction is 60℃~80℃ and the time is 24h~36h.

[0017] Preferably, the chemical structural formula of the perfluorosulfonic acid resin is as follows: .

[0018] Preferably, the acyl chloride reagent is sulfoxide or phosphorus trichloride; the catalyst is pyridine; and the first solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide, and N-methylpyrrolidone.

[0019] The third objective of this invention is to provide an anion exchange membrane, the preparation method of which is as follows: An alkylation reaction is carried out in a first solvent with a perfluorosulfonamide resin, an alkylating agent and an acid binder to graft quaternary ammonium cations onto the nitrogen heterocycle of the perfluorosulfonamide resin to obtain a quaternized polymer. The quaternized polymer is dissolved in a second solvent, cast into a membrane, and then treated with an alkali solution to obtain an anion exchange membrane.

[0020] Preferably, the ratio of perfluorosulfonamide resin to alkylating agent is 1g:1mL to 2mL.

[0021] Preferably, the quaternization reaction conditions are: room temperature and light protection for 24 hours.

[0022] Preferably, the alkylating agent is iodomethane.

[0023] Preferably, at least one of the acid binders Cs2CO3, K2CO3, and Na2CO3.

[0024] Preferably, the second solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone.

[0025] Preferably, the thickness of the anion exchange membrane is 48 μm to 52 μm.

[0026] Preferably, the alkaline solution is a KOH solution or a NaOH solution.

[0027] Preferably, the perfluorosulfonamide resin anion exchange membrane is used as an ion exchange membrane in an alkaline anion exchange membrane water electrolysis hydrogen production device.

[0028] The preferred and specific application methods are as follows: The perfluorosulfonamide resin anion exchange membrane is treated with an alkaline solution to convert the ion exchange groups into hydroxide ions, and then placed between the anode and cathode chambers as a diaphragm and ion conductor to assemble an alkaline anion exchange membrane water electrolysis hydrogen production device.

[0029] During electrolysis, the membrane conducts OH- - The ions are separated to prevent the generated hydrogen from mixing with oxygen, thus achieving efficient and safe alkaline water electrolysis for hydrogen production.

[0030] Compared with the prior art, the present invention has the following technical effects: This invention utilizes a perfluorosulfonic acid resin to construct the main chain structure, whose high CF bond energy endows the material with intrinsic chemical inertness. Furthermore, a nitrogen-containing heterocyclic quaternary ammonium salt cationic group is introduced, directly anchored to the main chain via sulfonamide bonds. The rigid structure of the nitrogen-containing heterocycle generates significant steric hindrance, greatly hindering the release of OH groups. - Ions approach the quaternary ammonium salt center and initiate a Hoffmann elimination reaction, solving the problem of easy degradation of traditional quaternary ammonium salts in strong bases. Simultaneously, the hydrophobicity of the perfluorinated backbone and the hydrophilic groups of the nitrogen-containing heterocyclic quaternary ammonium salt enable effective microphase separation, self-assembling to form interconnected hydrophilic ion cluster channels. This continuous ion transport network, combined with the high ion exchange capacity of the quaternary ammonium salt groups themselves, ensures efficient conduction of hydroxide ions within the membrane, thereby achieving high ionic conductivity.

[0031] The key to the use of specific unilaterally reactive primary amine groups in this invention lies in its ability to induce significant microphase separation in the polymer without forming a cross-linked network. This structure significantly enhances ionic conductivity by constructing continuous hydrophilic ion channels formed by the aggregation of rigid nitrogen-containing quaternary ammonium salts and providing a readily migratable local chemical environment for hydroxide ions. Attached Figure Description

[0032] Figure 1 This is the chemical structural formula of the perfluorosulfonamide resin synthesized in this invention.

[0033] Figure 2 The image shows the infrared spectrum of the perfluorosulfonamide anion exchange membrane of Example 1.

[0034] Figure 3 The infrared spectrum of the perfluorosulfonamide anion exchange membrane in Example 2 is shown.

[0035] Figure 4 The ionic conductivity refers to the perfluorosulfonamide anion exchange membranes of Examples 1 to 4.

[0036] Figure 5 This is a durability test of the perfluorosulfonamide anion exchange membrane in Example 2. Detailed Implementation

[0037] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention will be further described below with reference to specific embodiments and accompanying drawings. Unless otherwise specified, all reagents used in this invention are commercially available, and all methods used are conventional techniques in the art.

[0038] Example 1 A method for preparing a perfluorosulfonamide type anion exchange membrane includes the following steps: 5g of perfluorosulfonic acid resin was placed in a 100mL round-bottom flask, 80mL of thionyl chloride was added, and the mixture was refluxed at 90℃ for 12 hours. After cooling to room temperature, excess thionyl chloride was removed by rotary evaporation. Then, the mixture was distilled with 25mL of toluene. After cooling to room temperature, the mixture was dried overnight in a vacuum oven at 80℃ to obtain perfluorosulfonyl chloride resin.

[0039] 4.0 g of perfluorosulfonyl chloride resin was dispersed in 40 mL of N,N-dimethylformamide. 4 g of 4-amino-1-methylpiperidine and 40 mL of pyridine were added in an ice bath (0 °C) and stirred for 4 h. After returning to room temperature, the mixture was heated to 60 °C and refluxed for 24 h before rotary evaporation to obtain perfluorosulfonamide resin.

[0040] 3 g of perfluorosulfonamide was dispersed in 45 mL of N,N-dimethylformamide and heated at 70 °C. After the solution cooled to room temperature, 0.98 g of Cs₂CO₃ as an acid binder and 1 g of iodomethane as an alkylating agent were added, and the reaction was carried out at 40 °C in the dark for 24 hours. After the reaction was completed, the product was separated using ethyl acetate and washed repeatedly with deionized water. The washed polymer was placed in a 1 M KOH solution and stirred for 12 hours, followed by washing with deionized water to remove excess KOH. Finally, the product was freeze-dried under vacuum to obtain a brown quaternized perfluorosulfonamide resin.

[0041] 1 g of quaternized perfluorosulfonamide resin was dissolved in dimethyl sulfoxide and stirred at 160 °C for 3 hours. The solution was then coated onto a glass petri dish, and the solvent was removed by evaporation at 80 °C. After complete evaporation of the dimethyl sulfoxide, a perfluorosulfonamide resin film with a thickness of approximately 50 ± 2 μm was peeled off from the petri dish. The perfluorosulfonamide resin film was then immersed in a 1 M KOH solution for 12 hours to completely convert it to OH-. - The perfluorosulfonamide anion exchange membrane was obtained in the following manner:

[0042] .

[0043] Example 2 A method for preparing a perfluorosulfonamide type anion exchange membrane includes the following steps: 5g of perfluorosulfonic acid resin was placed in a 100mL round-bottom flask, 60mL of thionyl chloride was added, and the mixture was refluxed at 100℃ for 8 hours. After cooling to room temperature, excess thionyl chloride was removed by rotary evaporation. Then, the mixture was distilled with 20mL of toluene, cooled to room temperature, and dried under vacuum at 80℃ overnight to obtain perfluorosulfonyl chloride resin.

[0044] 4.0 g of perfluorosulfonyl chloride resin was dispersed in 40 mL of N,N-dimethylformamide. 4 g of 1-(2-aminoethyl)pyrrolidine and 40 mL of pyridine were added in an ice bath (0 °C) and stirred for 4 h. After returning to room temperature, the mixture was heated to 60 °C and refluxed for 24 h before rotary evaporation to obtain perfluorosulfonamide resin.

[0045] 3 g of perfluorosulfonamide was dispersed in 45 mL of DMSO and heated at 70 °C. After the solution cooled to room temperature, 0.98 g of Cs₂CO₃ as an acid binder and 1 g of iodomethane as an alkylating agent were added. The reaction was carried out at 40 °C in the dark for 24 hours. After the reaction was completed, the product was separated using ethyl acetate and washed repeatedly with deionized water. The washed polymer was placed in a 1 M KOH solution and stirred for 12 hours, followed by washing with deionized water to remove excess KOH. Finally, the product was freeze-dried under vacuum to obtain a brown quaternized perfluorosulfonamide resin.

[0046] 1 g of quaternized perfluorosulfonamide resin was dissolved in dimethyl sulfoxide and stirred at 160 °C for 3 hours. The solution was then coated onto a glass petri dish, and the solvent was removed by evaporation at 80 °C. After complete evaporation of the dimethyl sulfoxide, a perfluorosulfonamide resin film with a thickness of approximately 50 ± 2 μm was peeled off from the petri dish. The perfluorosulfonamide resin film was then immersed in a 1 M KOH solution for 12 hours to completely convert it to OH-. - The perfluorosulfonamide anion exchange membrane was obtained in this manner, and its chemical structural formula is as follows:

[0047] .

[0048] Example 3 A method for preparing a perfluorosulfonamide anion exchange membrane, differing from Example 1 in that (S)-3-aminoquinine cycloamine dihydrochloride is used instead of 4-amino-1-methylpiperidine, and the chemical structural formula of the resulting perfluorosulfonamide anion exchange membrane is as follows: .

[0049] Example 4 A method for preparing a perfluorosulfonamide anion exchange membrane, differing from Example 1 in that N-(2-aminoethyl)morpholine is used instead of 4-amino-1-methylpiperidine, and the chemical structural formula of the resulting perfluorosulfonamide anion exchange membrane is as follows: .

[0050] Experimental testing.

[0051] Figure 1 This is the chemical structural formula of the perfluorosulfonamide resin synthesized in this invention.

[0052] like Figure 2 As shown, the perfluorosulfonamide anion exchange membrane of Example 1 at 3072 cm⁻¹ -1 and 1523cm -1 Stretching vibration peaks of NH bonds were observed in the vicinity, with the peak at 1523 cm⁻¹. -1 The peak is more pronounced at 1453cm; -1 The nearby vibrational peak belongs to the stretching vibration peak of -CH3 in 4-amino-1-methylpiperidine, at 1154 cm⁻¹. -1 The nearby vibrational peak corresponds to the stretching vibration of the CF3 group, 981 cm⁻¹. -1 and 1057cm -1 The nearby peaks are attributed to -COC- and SO3, respectively. - The stretching vibrations were observed. Perfluorosulfonyl chloride, however, did not exhibit NH-related signals in the corresponding region, clearly distinguishing it from the other two. These characteristic peaks further verified the structural assignments of the functional groups in each compound, consistent with the chemical structures of the substances.

[0053] like Figure 3 As shown, in the infrared spectrum of Example 2, 1-(2-aminoethyl)pyrrolidine is at 3358 cm⁻¹. -1 A broad absorption peak appears nearby, attributed to the stretching vibration characteristic peak of -NH2, indicating the presence of a primary amine group in the structure. Perfluorosulfonamide shows an absorption peak at 3044 cm⁻¹. -1 A stretching vibration peak of NH bonds appears nearby, at 1238 cm⁻¹. -1 The strong absorption peak nearby corresponds to SO2 - Asymmetric stretching vibration of the group, 1154 cm⁻¹ -1 The nearby vibrational peak corresponds to the stretching vibration of the CF2 group, 1057 cm⁻¹. -1 The nearby peaks correspond to SO3. - Symmetric stretching vibrations. Perfluorosulfonyl chloride did not show NH-related signals in the corresponding region, but at 1238 cm⁻¹... -1 and 1154cm -1 SO3, similar to that of perfluorosulfonamide, was present nearby. - And CF2 characteristic absorption. These characteristic peaks further verified the structural assignment of functional groups in each compound, which is consistent with the chemical structure of the substance.

[0054] like Figure 4As shown, at 80°C, the conductivity of the perfluorosulfonamide anion exchange membrane prepared in Example 1 was 122 mS / cm; the conductivity of the perfluorosulfonamide anion exchange membrane prepared in Example 2 was 126 mS / cm; the conductivity of the perfluorosulfonamide anion exchange membrane prepared in Example 3 was 104 mS / cm; and the conductivity of the perfluorosulfonamide anion exchange membrane prepared in Example 4 was 94 mS / cm.

[0055] like Figure 5 As shown, at 60℃ and 1A / cm 2 An in-situ durability test was conducted at a current density of 1000 hours. The perfluorosulfonamide anion exchange membrane prepared in Example 2 maintained a stable cell voltage of approximately 1.94V in an alkaline anion exchange membrane fuel cell, with a decay rate of 453uv / h.

[0056] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended scope of protection is intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of this invention.

[0057] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of protection of this invention and its equivalents, this invention also intends to include these modifications and variations.

Claims

1. A perfluorosulfonamide resin, characterized in that, The chemical structural formula of the perfluorosulfonamide resin is as follows: ； In the formula, x is an integer between 1 and 3, y is an integer between 1 and 3, and m:n = 3 to 5:1; R is selected from one of the following groups: 。 2. A method for preparing the perfluorosulfonamide resin according to claim 1, characterized in that, Includes the following steps: Perfluorosulfonic acid resin is dissolved in an acyl chloride reagent and subjected to an acyl chloride reaction to obtain perfluorosulfonyl chloride resin; Perfluorosulfonyl chloride resin, an amine derivative containing a nitrogen heterocycle, and a first solvent undergo an amidation reaction under the action of a catalyst to obtain a perfluorosulfonamide resin.

3. The method for preparing the perfluorosulfonamide resin according to claim 2, characterized in that, Amine derivatives containing nitrogen heterocycles include N-(2-aminoethyl)morpholine, (S)-3-aminoquinine cyclic amine dihydrochloride, 1-(2-aminoethyl)pyrrolidine, or 4-amino-1-methylpiperidine.

4. The method for preparing the perfluorosulfonamide resin according to claim 2, characterized in that, The ratio of perfluorosulfonyl chloride resin, nitrogen-containing heterocyclic amine derivatives to catalyst is 1g:1g~2g:0.5mL~1mL; the mass ratio of perfluorosulfonic acid resin to acyl chloride reagent is 1:12~50.

5. The method for preparing the perfluorosulfonamide resin according to claim 2, characterized in that, The temperature for amidation is 60℃~80℃; the temperature for acyl chloride reaction is 90℃~100℃.

6. The method for preparing the perfluorosulfonamide resin according to claim 2, characterized in that, The catalyst is pyridine; the acyl chloride reagent is sulfoxide or phosphorus trichloride; the first solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide, and N-methylpyrrolidone.

7. An anion exchange membrane, characterized in that, The anion exchange membrane is obtained by quaternizing the perfluorosulfonamide resin of claim 1, forming a film, and then subjecting it to hydroxide ion exchange treatment by immersion in alkaline solution.

8. The anion exchange membrane according to claim 7, characterized in that, The preparation method of anion exchange membrane is as follows: An alkylation reaction is carried out in a first solvent with a perfluorosulfonamide resin, an alkylating agent and an acid binder to graft quaternary ammonium salt nitrogen cations onto the nitrogen heterocycle of the perfluorosulfonamide resin to obtain a quaternized polymer. The quaternized polymer is dissolved in a second solvent, cast into a membrane, and then treated with an alkali solution to obtain an anion exchange membrane.

9. The anion exchange membrane according to claim 8, characterized in that, The ratio of perfluorosulfonamide resin to alkylating agent is 1g:1mL~2mL; At least one of the acid binding agents Cs2CO3, K2CO3, and Na2CO3; The second solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone.

10. The anion exchange membrane according to claim 7, characterized in that, The thickness of the anion exchange membrane is 48 μm to 52 μm.

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