Polycarbazolyl nitrogen-containing derivatives, anion exchange membranes, and preparation methods and applications thereof

Abstract

The present invention discloses a polycarbazolyl nitrogen-containing derivative, an anion exchange membrane, and a preparation method and application thereof, relating to the technical field of polymer compounds. The polycarbazolyl anion exchange membrane provided by the present invention is a matrix, showing high stability, and 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide has a diquaternary ammonium cation structure, which can be grafted onto the polycarbazolyl matrix to significantly improve the conductivity of the membrane. The present invention adopts a superacid-catalyzed polymerization method to prepare a high ion exchange capacity anion exchange membrane with a microphase separation structure. The prepared anion exchange membrane has the characteristics of high ion exchange capacity, good alkali resistance and stability, and the method is simple and easy to industrialize. This anion exchange membrane has important application value in industries related to the field of hydrogen energy, such as alkaline fuel cells, water electrolysis hydrogen production, liquid flow batteries, and electrochemical ammonia synthesis.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer compounds, and in particular to a polycarbazolyl nitrogen-containing derivative, an anion exchange membrane, and a preparation method and application thereof. Background Art

[0002] As a key material in the hydrogen energy field, alkaline anion exchange membranes are widely used in alkaline fuel cells, water electrolysis for hydrogen production, CO2 reduction, electrochemical ammonia synthesis, and flow batteries. Three key factors determine their performance: chemical stability, which directly determines the material's performance; mechanical stability, which primarily affects the membrane's durability; and ionic conductivity, which directly influences the membrane's ion conduction performance.

[0003] In terms of chemical stability, high chemical stability can extend the service life of anion exchange membranes under high-temperature, high-alkaline conditions. The chemical stability of anion exchange membranes primarily depends on the alkaline stability of the polymer backbone and ionized groups. Current research on anion exchange membrane backbone materials focuses primarily on polyolefins, polyetheretherketones, polyphenylimidazoles, and polybiphenyls. Reports on poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membranes containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions are rare. Superacid-catalyzed polymerization is used to synthesize such membranes. The prior art discloses the preparation of anion exchange membranes using superacid-catalyzed polymerization. Numerous studies have demonstrated that ether-free backbone structures prepared using superacid-catalyzed polymerization exhibit relatively high chemical stability. Regarding mechanical stability, the mechanical stability of anion exchange membranes primarily depends on the rigidity of the polymer backbone, the flexibility of its side chains, and the degree of crosslinking. From the perspective of synthetic chemistry, anion exchange membranes have the following main challenges: (1) high degree of polymerization of the polymer backbone; (2) introduction and grafting degree of side chains; (3) controllable and appropriate cross-linking degree. For example, the currently commonly used polyarylether-based anion exchange membranes are synthesized mainly through superacid-catalyzed polymerization, but due to the rapid polymerization rate, gelation is easily caused, resulting in failure to form a membrane; while polyolefin-based anion exchange membranes are difficult to introduce side chains due to the limitation of polyolefin monomers. At the same time, in order to control the water absorption and swelling properties and phase separation structure of anion exchange membranes, the appropriate introduction of hydrophobic segments and groups is a development trend in the current anion exchange membrane research field. In terms of ion conductivity, an important role of anion exchange membranes is to transport hydroxide ions. High ion exchange capacity requires a high concentration of ionized groups per unit volume under the premise of consistent conduction mechanism. Therefore, the preparation of anion exchange membranes with high alkaline stability, high ion conductivity and good mechanical properties through convenient and efficient synthetic methods has always been the goal of scientific researchers. In order to achieve efficient ionic conductivity, it is necessary to develop new grafting methods to achieve a high grafting rate and to achieve the orderliness of the ionized groups through controllable means. This is also an important challenge in the current research field of anion exchange membranes.

[0004] Currently, reported anion exchange membranes for quaternary ammonium ions, such as N-methylpiperidine and quinine, exhibit good stability. However, their exchange capacity is limited and their conductivity is low. Therefore, it is crucial to explore new quaternary ammonium cations and develop novel alkaline anion exchange membranes with superior overall performance. Summary of the Invention

[0005] In response to the deficiencies in the above-mentioned background technology, the present invention primarily addresses the problems of low membrane conductivity and poor alkali stability in the prior art. The present invention provides a polycarbazolyl nitrogen-containing derivative, an anion exchange membrane, and a preparation method and application thereof. The method utilizes an electrophilic substitution reaction to synthesize 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide, then utilizes superacid-catalyzed polymerization to efficiently prepare poly[9-(6-bromohexyl)-9H-carbazolyl-co-trifluoroacetone], and finally utilizes a quaternization reaction to successfully prepare an anion exchange membrane of poly[9-(6-bromohexyl)-9H-carbazolyl-co-trifluoroacetone] containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions. The prepared polycarbazole-based anion exchange membrane is used as a matrix, showing high stability, and 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide has a diquaternary ammonium cation structure, which can be grafted on the polycarbazole-based matrix to greatly improve the conductivity of the membrane.

[0006] The first object of the present invention is to provide a polycarbazolyl nitrogen-containing derivative having the following general structural formula:

[0007]

[0008] Among them, n=300~350.

[0009] The second object of the present invention is to provide a method for preparing a polycarbazolyl nitrogen-containing derivative, comprising the following steps:

[0010] Dissolving poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] in an organic solvent, and then adding 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide to carry out a quaternization reaction to obtain the polycarbazolyl nitrogen-containing derivative;

[0011] The quaternization reaction temperature is 65-75°C and the reaction time is 20-30 hours.

[0012] The molar ratio of the 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide to poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] is 1:1-5.

[0013] Preferably, the 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide is prepared according to the following steps:

[0014] Catalyst I was added to a dry Teflon sealed tube, and then the Teflon sealed tube was replaced with nitrogen 2 to 6 times through a double-row tube. 1-Methylpiperazine, 1,5-dibromopentane, and solvent I were added, and the Teflon sealed tube was sealed. The temperature was set at 80 to 100°C, and the reaction was stirred for 10 to 20 hours, and then cooled to 10 to 30°C to obtain a reaction solution.

[0015] Add solvent II to the reaction solution to dilute it, and then filter it through celite to obtain a filtrate;

[0016] The filtrate is concentrated and washed in sequence to obtain the 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide;

[0017] Wherein, the catalyst I is sodium sulfate, potassium sulfate, sodium carbonate or potassium carbonate; the solvent I is one or more of ether, methanol, ethanol, acetonitrile and dichloromethane; the solvent II is one or more of ethanol, acetonitrile and dichloromethane.

[0018] Preferably, the concentration of the catalyst I is 0.1-0.4 mol / L; the molar ratio of the catalyst I, 1-methylpiperazine and 1,5-dibromopentane is 1-4:1:1.

[0019] Preferably, the poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] is prepared according to the following steps:

[0020] Dissolve 9-(6-bromohexyl)-9H-carbazole in solvent IV to obtain solution C;

[0021] Trifluoroacetone was added to solution C, and the reaction was continued in an ice bath for 10 to 30 minutes. Catalysts II and III were then added, and the reaction was continued in an ice bath for 10 to 60 minutes. The ice bath was then removed and the reaction was continued at room temperature for 0.5 to 2 hours to obtain solution D.

[0022] Solvent IV is added to solution D for dilution, and the diluted solution D is added to solvent V for precipitation to obtain poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone];

[0023] Wherein, the solvent IV is one or more of n-hexane, pyrrolidone, petroleum ether, and dichloromethane; the catalyst II is methanesulfonic acid or trifluoroacetic acid; the catalyst III is trifluoromethanesulfonic acid or trifluoroacetic acid; and the solvent V is one or more of methanol, ethanol, and distilled water.

[0024] Preferably, the concentration of 9-(6-bromohexyl)-9H-carbazole in solution C is 1 to 2 mol / L; and the molar ratio of catalyst II, catalyst III, trifluoroacetone, and 9-(6-bromohexyl)-9H-carbazole is 5 to 15:1 to 5:1 to 2:1. A third object of the present invention is to provide a polycarbazolyl nitrogen-containing derivative for use in ion exchange membranes.

[0025] The fourth object of the present invention is to provide an anion exchange membrane prepared using a polycarbazolyl nitrogen-containing derivative.

[0026] A fifth object of the present invention is to provide a method for preparing an anion exchange membrane, comprising the following steps:

[0027] dissolving a polycarbazolyl nitrogen-containing derivative in solvent VII to obtain solution G;

[0028] Pour solution G onto a glass plate, scrape the film and dry it to obtain an anion exchange membrane;

[0029] Wherein, the solvent VII is one or more of n-hexane, dimethyl sulfoxide, N,N-dimethylformamide, and dichloromethane.

[0030] The sixth object of the present invention is to provide an anion exchange membrane for use in alkaline fuel cells, water electrolysis to produce hydrogen, CO2 reduction, electrochemical ammonia synthesis or liquid flow batteries.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention provides a polycarbazol-based nitrogen-containing derivative, an anion exchange membrane, and a preparation method and application thereof. The polycarbazol-based nitrogen-containing derivative provided by the present invention is synthesized by using an electrophilic substitution reaction to synthesize 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide, then poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] is efficiently prepared by superacid-catalyzed polymerization, and finally a quaternization reaction is performed to obtain the obtained product. The present invention uses a poly(9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone) anion exchange membrane of 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ion prepared from a polycarbazole-based nitrogen-containing derivative, which has the following advantages: (1) high conductivity, which can reach 203 ms / cm at 80°C, which is higher than most anion exchange membranes; (2) good dimensional stability, with a water absorption swelling ratio of only 3.68% at 80°C; and (3) improved alkali resistance of the anion exchange membrane. The membrane can still maintain 64% of its initial conductivity after being immersed in a 2M NaOH solution for 120 hours.

[0033] The present invention provides a polycarbazole-based anion exchange membrane containing nitrogen-containing heterocyclic cations. The nitrogen-containing heterocyclic cations have a structure similar to that of the bispiperidinium cation, thereby significantly improving the conductivity of the anion exchange membrane and thereby improving the electrochemical performance of the anion exchange membrane. The main chain of carbazole and trifluoroacetone arranged alternately is hydrophobic, and the six carbon alkyl side chains are hydrophilic, constructing a microphase separation structure, which is conducive to OH - Ion transport within anion exchange membranes. Polycarbazolyl-based anion exchange membranes containing nitrogen heterocyclic cations have high electrical conductivity and good alkali resistance, and have good application prospects in the energy field. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1This is the H NMR spectrum of 9-(6-bromohexyl)-9H-carbazole (BHC).

[0035] Figure 2 This is the H NMR spectrum of [9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] polymer (PC-Br).

[0036] Figure 3 H NMR spectrum of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolidazole[5,5]-6-ammonium bromide ion.

[0037] Figure 4 Fourier transform infrared spectrum of the anion exchange membrane of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ion.

[0038] Figure 5 SAXS pattern of anion exchange membrane of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolidazole[5,5]-6-ammonium bromide ion.

[0039] Figure 6 AFM image of anion exchange membrane of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolidazole[5,5]-6-ammonium bromide ions.

[0040] Figure 7 Stress-strain curves of anion exchange membranes containing poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions.

[0041] Figure 8 Tensile strength and elongation at break of anion exchange membranes based on poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions.

[0042] Figure 9 Thermogravimetric curve of anion exchange membrane of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ion.

[0043] Figure 10The conductivity of the anion exchange membrane of 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ion poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) at different temperatures.

[0044] Figure 11 The residual weight of the anion exchange membrane of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ion after treatment in Fenton's reagent at 40°C for different times.

[0045] Figure 12 Conductivity changes of anion exchange membranes containing poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions after immersion in 2M NaOH solution at 80°C for 120 h. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below with reference to specific embodiments and drawings, but the embodiments are not intended to limit the present invention.

[0047] The purpose of the present invention is to provide a polycarbazolyl nitrogen-containing derivative, an anion exchange membrane and its preparation method and application, so as to improve the problems of low membrane conductivity and poor alkali resistance stability in the prior art.

[0048] In order to achieve the above-mentioned object, the first aspect of the present invention provides a polycarbazolyl nitrogen-containing derivative, the general structural formula of which is as follows:

[0049]

[0050] Among them, n=300~350.

[0051] The polycarbazole-based nitrogen-containing derivative provided by the present invention is synthesized by reacting 9-(6-bromohexyl)-9H-carbazole, trifluoroacetone, and a quaternary ammonium salt of a nitrogen-containing heterocycle; wherein the molar ratio of the 9-(6-bromohexyl)-9H-carbazole to the trifluoroacetone is 1:1-2;

[0052] The molar ratio of the polymer obtained by copolymerizing 9-(6-bromohexyl)-9H-carbazole and trifluoroacetone to the nitrogen-containing heterocyclic quaternary ammonium salt is 1:1-5.

[0053] A second aspect of the present invention provides a method for preparing a polycarbazolyl nitrogen-containing derivative, comprising the following steps:

[0054] Dissolving poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] in an organic solvent, and then adding 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide to carry out a quaternization reaction to obtain the polycarbazolyl nitrogen-containing derivative;

[0055] The quaternization reaction temperature is 65-75°C and the reaction time is 20-30 hours.

[0056] The molar ratio of the 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide to poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] is 1:1-5.

[0057] In one embodiment, a method for preparing a polycarbazolyl nitrogen-containing derivative comprises the following steps:

[0058] Step 1: Weigh poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] and dissolve it in solvent VI. Stir until the solution becomes clear and transparent to obtain solution E. The concentration of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] is 0.10 to 0.30 mol / L. Solvent VI can be one of n-hexane, petroleum ether, N,N-dimethylformamide, and dichloromethane.

[0059] Step 2: Add 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide to solution E for quaternization reaction. Set the system temperature to 70°C and react for 24 hours to obtain solution F; wherein the molar ratio of 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide to poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] is 1:1-5;

[0060] Step 3: Pour solution F into a mold and place it in an oven to dry to obtain a light yellow film, which is the polycarbazolyl nitrogen-containing derivative.

[0061] Wherein, the 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide is prepared according to the following steps:

[0062] Catalyst I was added to a dry Teflon sealed tube, and then the Teflon sealed tube was replaced with nitrogen 2 to 6 times through a double-row tube. 1-Methylpiperazine, 1,5-dibromopentane, and solvent I were added, and the Teflon sealed tube was sealed. The temperature was set at 80 to 100°C, and the reaction was stirred for 10 to 20 hours, and then cooled to 10 to 30°C to obtain a reaction solution.

[0063] Add solvent II to the reaction solution to dilute it, and then filter it through celite to obtain a filtrate;

[0064] The filtrate is concentrated and washed in sequence to obtain the 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide;

[0065] Wherein, the catalyst I is sodium sulfate, potassium sulfate, sodium carbonate or potassium carbonate; the solvent I is one or more of ether, methanol, ethanol, acetonitrile and dichloromethane; the solvent II is one or more of ethanol, acetonitrile and dichloromethane.

[0066] The concentration of the catalyst I is 0.1-0.4 mol / L; the molar ratio of the catalyst I, 1-methylpiperazine and 1,5-dibromopentane is 1-4:1:1.

[0067] In one embodiment, a method for preparing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide comprises the following steps:

[0068] Step 1: Weigh catalyst I into a dry Teflon sealed tube. The catalyst I is sodium sulfate, potassium sulfate, sodium carbonate, or potassium carbonate;

[0069] Step 2: Replace nitrogen in the Teflon sealed tube through the double-row tube 2 to 6 times;

[0070] Step 3: Continue adding 1-methylpiperazine, 1,5-dibromopentane, and solvent I to the Teflon sealed tube to obtain solution A. The molar ratio of catalyst I, 1-methylpiperazine, and 1,5-dibromopentane is 1-4:1:1; solvent I can be one of diethyl ether, methanol, ethanol, acetonitrile, and dichloromethane; and the concentration of catalyst I is 0.1-0.4 mol / L.

[0071] Step 4: After sealing the Teflon tube, set the system temperature to 80-100°C, keep the temperature and continue stirring for 10-20 hours to obtain solution B;

[0072] Step 5: After cooling the system to 10-30°C, solvent II is added to dilute solution B, and the solution is filtered through diatomaceous earth to obtain filtrate A; the solvent II can be one of ethanol, acetonitrile, and dichloromethane;

[0073] Step 6: Concentrate filtrate A to obtain a solid, wash with solvent III, and filter to obtain the target compound as a white solid 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide. The solvent III can be petroleum ether or n-hexane.

[0074] Specifically, the poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] is prepared according to the following steps:

[0075] Dissolve 9-(6-bromohexyl)-9H-carbazole in solvent IV to obtain solution C;

[0076] Trifluoroacetone was added to solution C, and the reaction was continued in an ice bath for 10 to 30 minutes. Catalysts II and III were then added, and the reaction was continued in an ice bath for 10 to 60 minutes. The ice bath was then removed and the reaction was continued at room temperature for 0.5 to 2 hours to obtain solution D.

[0077] Solvent IV is added to solution D for dilution, and the diluted solution D is added to solvent V for precipitation to obtain poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone];

[0078] Wherein, the solvent IV is one or more of n-hexane, pyrrolidone, petroleum ether, and dichloromethane; the catalyst II is methanesulfonic acid or trifluoroacetic acid; the catalyst III is trifluoromethanesulfonic acid or trifluoroacetic acid; and the solvent V is one or more of methanol, ethanol, and distilled water.

[0079] The concentration of 9-(6-bromohexyl)-9H-carbazole in the solution C is 1-2 mol / L; the molar ratio of the catalyst II, catalyst III, trifluoroacetone, and 9-(6-bromohexyl)-9H-carbazole is 5-15:1-5:1-2:1.

[0080] In one embodiment, a method for preparing poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] comprises the following steps:

[0081] Step 1: Weigh 9-(6-bromohexyl)-9H-carbazole and dissolve it in solvent IV to obtain solution C. The concentration of 9-(6-bromohexyl)-9H-carbazole in solution C is 1-2 mol / L;

[0082] Step 2: Add solution C to a single-necked round-bottom flask placed in an ice bath and start stirring;

[0083] Step 3: After stirring for 10 to 30 minutes, trifluoroacetone was added;

[0084] Step 4: After continuing the reaction in an ice bath for 10 to 30 minutes, slowly add catalyst II and catalyst III, wherein the molar ratio of catalyst II, catalyst III, trifluoroacetone and 9-(6-bromohexyl)-9H-carbazole is 5 to 15:1 to 5:1 to 2:1;

[0085] Step 5: After continuing the reaction in the ice bath for 10 to 60 minutes, remove the ice bath and place the system at room temperature to react for 0.5 to 2 hours to obtain solution D;

[0086] Step 6: Add solvent IV to solution D for dilution;

[0087] Step 7: The diluted solution D was added dropwise to the solvent V for precipitation to obtain a white rubber crumb-like solid, which was then dried in vacuo to obtain poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone].

[0088] Among them, the catalyst II can be methanesulfonic acid or trifluoroacetic acid; the catalyst III can be trifluoromethanesulfonic acid or trifluoroacetic acid; the solvent IV can be one of n-hexane, pyrrolidone, petroleum ether, and dichloromethane; the solvent V can be one of methanol, ethanol, and distilled water.

[0089] A third aspect of the present invention provides a use of a polycarbazolyl nitrogen-containing derivative in an ion exchange membrane.

[0090] A fourth aspect of the present invention provides an anion exchange membrane prepared using a polycarbazolyl nitrogen-containing derivative.

[0091] A fifth aspect of the present invention provides a method for preparing an anion exchange membrane, comprising the following steps:

[0092] dissolving a polycarbazolyl nitrogen-containing derivative in solvent VII to obtain solution G;

[0093] Pour solution G onto a glass plate, scrape the film and dry it to obtain an anion exchange membrane;

[0094] Wherein, the solvent VII is one or more of n-hexane, dimethyl sulfoxide, N,N-dimethylformamide, and dichloromethane.

[0095] In one embodiment, a method for preparing an anion exchange membrane includes:

[0096] The polycarbazolyl nitrogen-containing derivative is dissolved in solvent VII to obtain a clear and transparent solution G.

[0097] Solution G is poured onto a glass plate, scraped, and placed in an oven to dry, thereby obtaining an anion exchange membrane of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions. The solvent VII is one of n-hexane, dimethyl sulfoxide, N,N-dimethylformamide, and dichloromethane.

[0098] A sixth aspect of the present invention provides an application of an anion exchange membrane in an alkaline fuel cell, water electrolysis to produce hydrogen, CO2 reduction, electrochemical ammonia synthesis or a liquid flow battery.

[0099] The present invention adopts superacid catalytic polymerization to prepare an anion exchange membrane with high ionic conductivity and high alkaline stability. The ionic conductivity of the prepared anion exchange membrane can reach above 200 ms / cm at 80°C, and it is a high ionic conductivity anion exchange membrane.

[0100] It should be noted that the experimental methods used in the present invention are all conventional methods unless otherwise specified; the reagents and materials used are all commercially available unless otherwise specified.

[0101] Example 1

[0102] A method for preparing a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions comprises:

[0103] In step 1, 0.33 g of sodium sulfate was weighed and added to a dry Teflon tube. The nitrogen atmosphere was replaced three times using a double-row tube. Subsequently, 0.1 g of 1-methylpiperazine, 0.23 g of 1,5-dibromopentane, and 10 mL of diethyl ether were added in sequence. The Teflon tube was then sealed, the system temperature was set to 80°C, and the reaction was maintained with continuous stirring for 10 hours. After cooling the system to 20°C, the ethanol-diluted solution B was added, and the mixture was filtered through diatomaceous earth to obtain filtrate A. Filtrate A was concentrated to obtain a solid, which was washed with petroleum ether and filtered to obtain the target compound as a white solid, 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide.

[0104] Step 2: Weigh 0.396 g of 9-(6-bromohexyl)-9H-carbazole and dissolve it in 0.8 mL of n-hexane to obtain solution C. Solution C is added to a single-necked round-bottom flask placed in an ice bath, and stirring is started. After stirring for 10 minutes, 0.21 mL of trifluoroacetone is added thereto; after continuing the reaction in the ice bath for 10 minutes, 0.39 mL of methanesulfonic acid and 0.21 mL of trifluoromethanesulfonic acid are slowly added; after continuing the reaction in the ice bath for 10 minutes, the ice bath is removed, and the system is placed at room temperature for reaction for 0.5 hours to obtain solution D; n-hexane is added to solution D for dilution; the diluted solution D is added dropwise to methanol for precipitation to obtain a white rubber crumb-like solid, which is vacuum dried to obtain poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone].

[0105] Step 3: Weigh 0.32 g of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] and dissolve it in 7.5 mL of n-hexane. Stir until the solution becomes clear and transparent, obtaining Solution E. Add 0.127 g of 3-methyl-3,6-diazooxazol[5,5]-6-ammonium bromide to Solution E for quaternization. Set the system temperature to 70°C and react for 24 hours to obtain Solution F. Pour Solution F into a mold and place it in an oven to dry, obtaining a pale yellow film. The obtained pale yellow film is dissolved in n-hexane until a clear and transparent Solution G is obtained. Pour Solution G onto a glass plate, scrape the film, and place it in an oven to dry, obtaining a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazooxazol[5,5]-6-ammonium bromide ions.

[0106] Example 2

[0107] A method for preparing a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions comprises:

[0108] In step 1, 0.35 g of potassium sulfate was weighed and added to a dry Teflon sealed tube. The nitrogen atmosphere was replaced twice using a double-row tube. Subsequently, 0.1 g of 1-methylpiperazine, 0.23 g of 1,5-dibromopentane, and 10 mL of methanol were added in sequence. The Teflon sealed tube was then sealed, the system temperature was set to 90°C, and the reaction was stirred continuously for 15 hours. After cooling the system to 25°C, acetonitrile-diluted solution B was added, and the mixture was filtered through diatomaceous earth to obtain filtrate A. Filtrate A was concentrated to obtain a solid, which was washed with n-hexane and filtered to obtain the target compound as a white solid, 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide.

[0109] Step 2: Weigh 0.264 g of 9-(6-bromohexyl)-9H-carbazole and dissolve it in 0.8 mL of pyrrolidone to obtain solution C; add solution C to a single-necked round-bottom flask placed in an ice bath and start stirring; after stirring for 20 minutes, add 0.07 mL of trifluoroacetone thereto; continue the reaction in the ice bath for 10 minutes, and then slowly add 0.26 mL of trifluoroacetic acid and 0.35 mL of trifluoromethanesulfonic acid; continue the reaction in the ice bath for 20 minutes, remove the ice bath, and let the system react at room temperature for 1 hour to obtain solution D; add pyrrolidone to solution D for dilution; and add the diluted solution D dropwise into ethanol for precipitation to obtain a white rubber crumb-like solid, which is vacuum dried to obtain poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone].

[0110] Step 3: Weigh 0.48 g of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] and dissolve it in 7.5 mL of n-hexane. Stir until the solution becomes clear and transparent, obtaining Solution E. Add 0.38 g of 3-methyl-3,6-diazooxazol[5,5]-6-ammonium bromide to Solution E for quaternization. Set the system temperature to 70°C and react for 24 hours to obtain Solution F. Pour Solution F into a mold and place it in an oven to dry, obtaining a pale yellow film. The obtained pale yellow film is dissolved in dimethyl sulfoxide until a clear and transparent Solution G is obtained. Pour Solution G onto a glass plate, scrape the film, and place it in an oven to dry, obtaining a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazooxazol[5,5]-6-ammonium bromide ions.

[0111] Example 3

[0112] A method for preparing a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions comprises:

[0113] In step 1, 0.33 g of sodium carbonate was weighed and added to a dry Teflon sealed tube. The nitrogen atmosphere was replaced five times using a double-row tube. Subsequently, 0.15 g of 1-methylpiperazine, 0.35 g of 1,5-dibromopentane, and 10 mL of ethanol were added in sequence. The Teflon sealed tube was then sealed, the system temperature was set to 100°C, and the reaction was stirred continuously for 16 hours. After cooling the system to 22°C, dilute Solution B with dichloromethane and filtered through diatomaceous earth to obtain Filtrate A. Filtrate A was concentrated to obtain a solid, which was washed with ether and filtered to obtain the target compound as a white solid, 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide.

[0114] Step 2: Weigh 0.396 g of 9-(6-bromohexyl)-9H-carbazole and dissolve it in 0.8 mL of dichloromethane to obtain solution C. Solution C is added to a single-necked round-bottom flask placed in an ice bath and stirred; after stirring for 10 minutes, 0.21 mL of trifluoroacetone is added thereto; after continuing the reaction in the ice bath for 20 minutes, 0.39 mL of methanesulfonic acid and 0.39 mL of trifluoroacetic acid are slowly added; after continuing the reaction in the ice bath for 30 minutes, the ice bath is removed and the system is placed at room temperature to react for 1 hour to obtain solution D; dichloromethane is added to solution D for dilution; the diluted solution D is added dropwise to distilled water for precipitation to obtain a white rubber crumb-like solid, which is vacuum dried to obtain poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone].

[0115] Step 3: Weigh 0.64 g of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] and dissolve it in 7.5 mL of N,N-dimethylformamide. Stir until the solution becomes clear and transparent, obtaining Solution E. Add 0.76 g of 3-methyl-3,6-diazo-oxazol[5,5]-6-ammonium bromide to Solution E for quaternization. Set the system temperature to 70°C and react for 24 hours to obtain Solution F. Pour Solution F into a mold and place it in an oven to dry, obtaining a pale yellow film. The obtained pale yellow film is dissolved in dimethyl sulfoxide until a clear and transparent Solution G is obtained. Pour Solution G onto a glass plate, scrape the film, and place it in an oven to dry, obtaining a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazo-oxazol[5,5]-6-ammonium bromide ions.

[0116] Example 4

[0117] A method for preparing a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions comprises:

[0118] In step 1, 0.28 g of potassium carbonate was weighed and added to a dry Teflon tube. The nitrogen atmosphere was replaced four times using a double-row tube. Subsequently, 0.1 g of 1-methylpiperazine, 0.23 g of 1,5-dibromopentane, and 10 mL of acetonitrile were added in sequence. The Teflon tube was then sealed, the system temperature was set to 90°C, and the reaction was stirred continuously for 16 hours. After cooling the system to 22°C, dilute Solution B with dichloromethane and filtered through diatomaceous earth to obtain Filtrate A. Filtrate A was concentrated to obtain a solid, which was washed with diethyl ether and filtered to obtain the target compound as a white solid, 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide.

[0119] Step 2: Weigh 0.475 g of 9-(6-bromohexyl)-9H-carbazole and dissolve it in 0.8 mL of petroleum ether to obtain solution C. Solution C is added to a single-necked round-bottom flask placed in an ice bath and stirred; after stirring for 30 minutes, 2.58 mL of trifluoroacetone is added thereto; after continuing the reaction in the ice bath for 20 minutes, 9.33 mL of methanesulfonic acid and 6.37 mL of trifluoromethanesulfonic acid are slowly added; after continuing the reaction in the ice bath for 40 minutes, the ice bath is removed and the system is allowed to react at room temperature for 1 hour to obtain solution D; dichloromethane is added to solution D for dilution; the diluted solution D is added dropwise to methanol for precipitation to obtain a white rubber crumb-like solid, which is vacuum dried to obtain poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone].

[0120] Step 3: Weigh 0.80 g of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] and dissolve it in 7.5 mL of dichloromethane. Stir until the solution becomes clear and transparent, obtaining Solution E. Add 1.268 g of 3-methyl-3,6-diazooxazol[5,5]-6-ammonium bromide to Solution E for quaternization. Set the system temperature to 70°C and react for 24 hours to obtain Solution F. Pour Solution F into a mold and place it in an oven to dry, obtaining a pale yellow film. The obtained pale yellow film is dissolved in dichloromethane until a clear and transparent Solution G is obtained. Pour Solution G onto a glass plate, scrape the film, and place it in an oven to dry, obtaining a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazooxazol[5,5]-6-ammonium bromide ions.

[0121] Example 5

[0122] A method for preparing a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions comprises:

[0123] In step 1, 0.34 g of sodium sulfate was weighed and added to a dry Teflon sealed tube. The nitrogen atmosphere was replaced six times using a double-row tube. Subsequently, 0.2 g of 1-methylpiperazine, 0.46 g of 1,5-dibromopentane, and 10 mL of dichloromethane were added in sequence. The Teflon sealed tube was then sealed, the system temperature was set to 90°C, and the reaction was stirred continuously for 20 hours. After cooling the system to 25°C, the ethanol-diluted solution B was added, and the mixture was filtered through diatomaceous earth to obtain filtrate A. Filtrate A was concentrated to obtain a solid, which was washed with ether and filtered to obtain the target compound as a white solid, 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide.

[0124] Step 2: Weigh 0.528 g of 9-(6-bromohexyl)-9H-carbazole and dissolve it in 0.8 mL of dichloromethane to obtain solution C. Solution C is added to a single-necked round-bottom flask placed in an ice bath and stirred; after stirring for 30 minutes, 0.29 mL of trifluoroacetone is added thereto; after continuing the reaction in the ice bath for 30 minutes, 1.55 mL of trifluoroacetic acid and 0.71 mL of trifluoromethanesulfonic acid are slowly added; after continuing the reaction in the ice bath for 20 minutes, the ice bath is removed and the system is placed at room temperature to react for 1.5 hours to obtain solution D; n-hexane is added to solution D for dilution; the diluted solution D is added dropwise to ethanol for precipitation to obtain a white rubber crumb-like solid, which is vacuum dried to obtain poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone].

[0125] Step 3: Weigh 0.96 g of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] and dissolve it in 7.5 mL of n-hexane. Stir until the solution becomes clear and transparent, obtaining Solution E. Add 1.901 g of 3-methyl-3,6-diazo-oxazol[5,5]-6-ammonium bromide to Solution E for quaternization. Set the system temperature to 70°C and allow the reaction to proceed for 24 hours to obtain Solution F. Pour Solution F into a mold and place it in an oven to dry, obtaining a pale yellow film. The resulting pale yellow film is dissolved in dimethyl sulfoxide to obtain a clear and transparent Solution G. Pour Solution G onto a glass plate, scrape the film, and dry it in an oven to obtain a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazo-oxazol[5,5]-6-ammonium bromide ions.

[0126] Example 6

[0127] A method for preparing a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions comprises:

[0128] In step 1, 0.28 g of potassium carbonate was weighed and added to a dry Teflon tube. The nitrogen atmosphere was replaced six times using a double-row tube. Subsequently, 0.2 g of 1-methylpiperazine, 0.46 g of 1,5-dibromopentane, and 10 mL of methanol were added in sequence. The Teflon tube was then sealed, the system temperature was set to 80°C, and the reaction was stirred continuously for 16 hours. After cooling the system to 20°C, acetonitrile-diluted solution B was added, and the mixture was filtered through diatomaceous earth to obtain filtrate A. Filtrate A was concentrated to obtain a solid, which was washed with petroleum ether and filtered to obtain the target compound as a white solid, 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide.

[0129] Step 2: Weigh 0.396 g of 9-(6-bromohexyl)-9H-carbazole and dissolve it in 0.8 mL of pyrrolidone to obtain solution C. Solution C was added to a single-necked round-bottom flask placed in an ice bath and stirred; after stirring for 10 minutes, 0.21 mL of trifluoroacetone was added thereto; after continuing to react in the ice bath for 20 minutes, 0.39 mL of methanesulfonic acid and 0.21 mL of trifluoromethanesulfonic acid were slowly added; after continuing to react in the ice bath for 20 minutes, the ice bath was removed and the system was allowed to react at room temperature for 0.5 hours to obtain solution D; dichloromethane was added to solution D for dilution; the diluted solution D was added dropwise to ethanol for precipitation to obtain a white rubber crumb-like solid, which was vacuum dried to obtain poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone].

[0130] Step 3: Weigh 0.38 g of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] and dissolve it in 7.5 mL of dichloromethane. Stir until the solution becomes clear and transparent, obtaining Solution E. Add 0.228 g of 3-methyl-3,6-diazooxazol[5,5]-6-ammonium bromide to Solution E for quaternization. Set the system temperature to 70°C and react for 24 hours to obtain Solution F. Pour Solution F into a mold and place it in an oven to dry, obtaining a pale yellow film. The obtained pale yellow film is dissolved in n-hexane to obtain a clear and transparent Solution G. Pour Solution G onto a glass plate, scrape the film, and place it in an oven to dry, obtaining a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazooxazol[5,5]-6-ammonium bromide ions.

[0131] Example 7

[0132] A method for preparing a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions comprises:

[0133] In step 1, 0.25 g of sodium carbonate was weighed and added to a dry Teflon tube. The nitrogen atmosphere was replaced four times using a double-row tube. Subsequently, 0.2 g of 1-methylpiperazine, 0.46 g of 1,5-dibromopentane, and 10 mL of dichloromethane were added in sequence. The Teflon tube was then sealed, the system temperature was set to 90°C, and the reaction was stirred continuously for 20 hours. After cooling the system to 22°C, ethanol-diluted solution B was added, and the mixture was filtered through diatomaceous earth to obtain filtrate A. Filtrate A was concentrated to obtain a solid, which was washed with petroleum ether and filtered to obtain the target compound as a white solid, 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide.

[0134] Step 2: Weigh 0.528 g of 9-(6-bromohexyl)-9H-carbazole and dissolve it in 0.8 mL of n-hexane to obtain solution C. Solution C is added to a single-necked round-bottom flask placed in an ice bath and stirred; after stirring for 30 minutes, 0.14 mL of trifluoroacetone is added thereto; after continuing the reaction in the ice bath for 30 minutes, 1.55 mL of trifluoroacetic acid and 0.71 mL of trifluoromethanesulfonic acid are slowly added; after continuing the reaction in the ice bath for 40 minutes, the ice bath is removed and the system is placed at room temperature to react for 1 hour to obtain solution D; petroleum ether is added to solution D for dilution; the diluted solution D is added dropwise to distilled water for precipitation to obtain a white rubber crumb-like solid, which is vacuum dried to obtain poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone].

[0135] Step 3: Weigh 0.57 g of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] and dissolve it in 7.5 mL of N,N-dimethylformamide. Stir until the solution becomes clear and transparent, obtaining Solution E. Add 0.456 g of 3-methyl-3,6-diazooxazol[5,5]-6-ammonium bromide to Solution E for quaternization. Set the system temperature to 70°C and react for 24 hours to obtain Solution F. Pour Solution F into a mold and place it in an oven to dry, obtaining a pale yellow film. The obtained pale yellow film is dissolved in n-hexane to obtain a clear and transparent Solution G. Pour Solution G onto a glass plate, scrape the film, and place it in an oven to dry, obtaining a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazooxazol[5,5]-6-ammonium bromide ions.

[0136] In order to illustrate the relevant performance of the anion exchange membrane provided by the present invention, it is described in conjunction with the accompanying drawings.

[0137] Figure 1 This is the H NMR spectrum of 9-(6-bromohexyl)-9H-carbazole (BHC). Figure 1 This is the H NMR spectrum of monomer 9-(6-bromohexyl)-9H-carbazole, not the sample of Example. Figure 1 The chemical shifts assigned to the protons can show the chemical structure of 9-(6-bromohexyl)-9H-carbazole. The chemical shifts of the peaks corresponding to protons 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 are 8.02, 7.38, 7.31, 7.15, 4.21, 3.26, 1.80, 1.71, 1.38, and 1.30 ppm, respectively.

[0138] Figure 2 This is the H NMR spectrum of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (PC-Br). Figure 2 This is the sample data of Example 6, Figure 2 The chemical shifts of the protons of PC-Br in DMF-d7 are assigned to a, b, c, d, i, j, (e, h), and (f, g), and the corresponding peak positions are 8.43, 7.56, 7.33, 4.51, 2.72, 2.17, 1.77–1.69, and 1.41–1.33 ppm, respectively, which proves that the PC-Br polymer was successfully prepared in the present invention.

[0139] Figure 3 H NMR spectrum of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ion. Figure 3 This is the sample data of Example 6, Figure 3 The chemical shifts of the protons of QPC-DDMP in DMSO-d6 are assigned to a', b', c', d', k, i', j', (e', h'), (l, m), and (f', g'), and the corresponding peak positions are 8.33, 7.55, 7.16, 4.28, 3.93-3.71, 3.23, 2.11, 1.75-1.63, 1.54-1.49, and 1.39-1.22 ppm, respectively, which proves that the QPC-DDMP polymer film was successfully prepared in the present invention.

[0140] Figure 4 Fourier transform infrared spectra of anion exchange membranes containing 9-(6-bromohexyl)-9H-carbazole (BHC), poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (PC-Br), and poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions. Figure 4 This is the sample data of Example 6, Figure 4 Middle 2857 cm -1 The stretching vibration peak corresponding to the methylene group is 1607 cm -1 , 1489 cm -1 Corresponding to the vibration absorption of C=C on the aromatic ring skeleton of carbazole, 1138 cm -1 The peak at 803 cm is attributed to the CF absorption peak. -1 The peak at is attributed to the out-of-plane bending vibration of =CH on the aromatic ring of carbazole, which proves that the present invention successfully prepared PC-Br polymer and QPC-DDMP polymer films.

[0141] Figure 5 SAXS pattern of anion exchange membrane of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ion. Figure 5 The sample data of Example 6 shows that the distribution of hydrophilic and hydrophobic segments in the anion exchange membrane forms a microphase separation structure, which is conducive to the formation of ion channels. The hydrophilic and hydrophobic microphase separation structure of the anion exchange membrane can be further analyzed and characterized using small-angle X-ray diffraction (SAXs) and atomic force microscopy (AFM). Figure 5 The small-angle X-ray diffraction curves shown in the figure show that the QPC-DDMP film has obvious diffraction peaks, and the scattering intensities of QPC-DDMP are 0.26 nm -1, indicating that there is a microphase separation structure formed by ion cluster aggregation in the QPC-DDMP membrane. According to the Bragg formula d = 2π / q max The calculated distance between ion cluster domains in QPC-DDMP membrane is 24 nm.

[0142] Figure 6 AFM image of anion exchange membrane of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions. Figure 6 For example 6 sample data, Figure 6 AFM analysis revealed the microphase separation structure of the anion exchange membrane. The black portion represents the hydrophobic region, while the brown portion represents the hydrophilic region. This clearly demonstrates the microphase separation structure of the anion exchange membrane, a result that corroborates the SAXS results. The above description demonstrates that the QPC-DDMP membrane possesses a well-defined microphase separation structure. This structure is primarily determined by the differences in chain arrangement between the rigid aromatic backbone and the flexible aliphatic side chains. The rigid and curved backbone structure forms the hydrophobic segments, while the ion-conductive groups on the flexible side chains effectively aggregate into the hydrophilic segments, ultimately forming a distinct microphase separation structure.

[0143] Figure 7 Stress-strain curves of anion exchange membrane composed of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ion. Figure 8 The tensile strength and elongation at break of anion exchange membranes of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions are shown; Figure 7 and Figure 8 These are all sample data from Example 6. The anion exchange membrane needs to maintain good mechanical properties during use, otherwise it will affect the service life of the device. Figures 7 and 8 As shown in the figure, the tensile strength of the QPC-DDMP membrane is 14.3 MPa and the elongation at break is 12.2%. The rigid main chain structure and flexible side chain structure in the QPC-DDMP membrane enable it to achieve good mechanical properties.

[0144] Figure 9 Thermogravimetric curve of anion exchange membrane of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ion. Figure 9The data for the samples in Example 6 are as follows. Due to the high operating temperature (60-80°C) of anion exchange membranes in the hydrogen energy field, the thermal stability of AEM should be paid special attention to during long-term use. The thermal weight loss curve of the QPC-DDMP polymer film is as follows: Figure 9 As shown, the initial degradation temperature of the QPC-DDMP membrane is greater than 180°C, which is much higher than the actual operating temperature of anion exchange membranes. This indicates that the prepared QPC-DDMP membrane has good thermal stability and great application potential in the hydrogen energy field. The thermal weight loss of the QPC-DDMP membrane mainly occurs in three stages. The first weight loss stage around 30-180°C corresponds to the evaporation of bound water and residual solvent in the membrane. The weight loss between 180°C and 380°C is due to the degradation of the side chain structure and cationic groups. After 380°C, the final degradation stage is mainly due to the degradation of the poly(carbazole-co-trifluoroacetone) backbone.

[0145] Figure 10 The conductivity of the anion exchange membrane of 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ion poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) at different temperatures. Figure 10 For example 6 sample data, Figure 10 As shown in the figure, the conductivity of QPC-DDMP membrane increases with increasing temperature. At 80℃, the conductivity of QPC-DDMP is the highest, reaching 203 mS / cm, which proves that QPC-DDMP membrane has good electrochemical performance in the field of hydrogen energy.

[0146] Figure 11 The residual weight of the anion exchange membrane of poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ion after treatment in Fenton's reagent at 40°C for different times. Figure 11 The sample data of Example 6 shows that the QPC-DDMP membrane was immersed in Fenton's reagent for oxidation stability testing. After 168 hours, the QPC-DDMP membrane can maintain 93.1% of its initial weight, indicating that the QPC-DDMP membrane has good oxidation stability.

[0147] Figure 12 Conductivity changes of anion exchange membranes containing poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] (QPC-DDMP) containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions after immersion in 2M NaOH solution at 80°C for 120 h. Figure 12 The sample data of Example 6 shows that the hydroxide ion conductivity of QPC-DDMP can maintain 44.3% of the initial conductivity after accelerated alkali resistance test.

[0148] In summary, the present invention provides a poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] anion exchange membrane containing 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide ions. The prepared polycarbazole-based anion exchange membrane is used as a matrix, showing high stability, and 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide has a diquaternary ammonium cation structure, which can be grafted onto the polycarbazole-based matrix to greatly improve the conductivity of the membrane. The present invention adopts a superacid catalyzed polymerization method to prepare a high ion exchange capacity anion exchange membrane with a microphase separation structure. The prepared anion exchange membrane has the characteristics of high ion exchange capacity, good alkali resistance and stability, and the method is simple and easy to industrialize. This anion exchange membrane has important application value in industries related to hydrogen energy such as alkaline fuel cells, water electrolysis hydrogen production, liquid flow batteries, and electrochemical ammonia synthesis.

Claims

1. A method for preparing an anion exchange membrane, characterized in that: The following steps are involved: dissolving a polycarbazolyl nitrogen-containing derivative in solvent VII to obtain solution G; Pour solution G onto a glass plate, scrape the film and dry it to obtain an anion exchange membrane; wherein the solvent VII is one or more of n-hexane, dimethyl sulfoxide, N,N-dimethylformamide, and dichloromethane; The general structural formula of the polycarbazolyl nitrogen-containing derivative is as follows: Among them, n=300~350; The polycarbazolyl nitrogen-containing derivative is prepared according to the following steps: Dissolving poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] in an organic solvent, and then adding 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide to carry out a quaternization reaction to obtain the polycarbazolyl nitrogen-containing derivative; The quaternization reaction temperature is 65-75°C and the reaction time is 20-30 hours. The molar ratio of the 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide to poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] is 1:1-5; The 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide is prepared according to the following steps: Catalyst I was added to a dry Teflon sealed tube, and then the Teflon sealed tube was replaced with nitrogen 2 to 6 times through a double-row tube. 1-Methylpiperazine, 1,5-dibromopentane, and solvent I were added, and the Teflon sealed tube was sealed. The temperature was set at 80 to 100°C, and the reaction was stirred for 10 to 20 hours, and then cooled to 10 to 30°C to obtain a reaction solution. Add solvent II to the reaction solution to dilute it, and then filter it through celite to obtain a filtrate; The filtrate is concentrated and washed in sequence to obtain the 3-methyl-3,6-diazolyl[5,5]-6-ammonium bromide; Wherein, the catalyst I is sodium sulfate, potassium sulfate, sodium carbonate or potassium carbonate; the solvent I is one or more of ether, methanol, ethanol, acetonitrile and dichloromethane; the solvent II is one or more of ethanol, acetonitrile and dichloromethane; The poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone] is prepared according to the following steps: 9-(6-bromohexyl)-9H-carbazole was dissolved in solvent IV to obtain solution C; Trifluoroacetone was added to solution C, and the reaction was continued in an ice bath for 10 to 30 minutes. Catalysts II and III were then added, and the reaction was continued in an ice bath for 10 to 60 minutes. The ice bath was then removed and the reaction was continued at room temperature for 0.5 to 2 hours to obtain solution D. Solvent IV is added to solution D for dilution, and the diluted solution D is added to solvent V for precipitation to obtain poly[9-(6-bromohexyl)-9H-carbazole-co-trifluoroacetone]; Wherein, the solvent IV is one or more of n-hexane, pyrrolidone, petroleum ether, and dichloromethane; the catalysts II and III are methanesulfonic acid and trifluoroacetic acid, or trifluoroacetic acid and trifluoromethanesulfonic acid, or methanesulfonic acid and trifluoromethanesulfonic acid; and the solvent V is one or more of methanol, ethanol, and distilled water.

2. The method for preparing an anion exchange membrane according to claim 1, wherein The concentration of the catalyst I is 0.1-0.4 mol / L; the molar ratio of the catalyst I, 1-methylpiperazine and 1,5-dibromopentane is 1-4:1:

1.

3. The method for preparing an anion exchange membrane according to claim 1, wherein The concentration of 9-(6-bromohexyl)-9H-carbazole in the solution C is 1-2 mol / L; the molar ratio of the catalyst II, catalyst III, trifluoroacetone, and 9-(6-bromohexyl)-9H-carbazole is 5-15:1-5:1-2:

1.

4. An anion exchange membrane prepared by the method according to any one of claims 1 to 3.

5. Use of the anion exchange membrane according to claim 4 in alkaline fuel cells, water electrolysis for hydrogen production, CO2 reduction, electrochemical ammonia synthesis or liquid flow batteries.

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