Preparation method of ferrocene derivative anion exchange membrane

Abstract

The present invention provides a ferrocene derivative anion exchange membrane and a preparation method thereof. The anion exchange membrane includes: ethyl side chain type polyindigo biphenyl, butyl side chain type polyindigo biphenyl and hexyl side chain type polyindigo biphenyl according to different grafted side chain lengths. The present invention also provides a ferrocene derivative anion exchange membrane and a preparation method thereof, the method is to prepare the polyindigo biphenyl polymer by a step-growth polymerization reaction catalyzed by a superacid, and to prepare an anion exchange membrane containing a ferrocene derivative by a nucleophilic substitution reaction. The ferrocene derivative anion exchange membrane of the present invention has a hydroxide conductivity of 0.059S / cm at 80°C.

Description

Technical Field

[0001] The invention belongs to the field of polymer materials and anion exchange membrane fuel cells, and in particular relates to a method for preparing a ferrocene derivative anion exchange membrane. Background Art

[0002] A fuel cell is an electrochemical device that converts chemical energy into electrical energy with the only byproduct being water. It has become a research hotspot because of its environmental friendliness, sustainable development and huge potential for application. Anion exchange membrane is one of the core components of alkaline fuel cells and an important factor affecting the performance of fuel cells. After years of development, the performance of anion exchange membranes has been greatly improved, but at present, it still cannot meet the needs of daily use in terms of ion conductivity, mechanical properties and alkaline stability.

[0003] Among them, the main factors affecting the performance of anion exchange membranes are the properties of the polymer backbone and ion transport groups. Zhu et al. (J. Mater. Chem. A, 2019, 7, 6883-6893) synthesized a high molecular polymer with excellent chemical and mechanical stability at low temperature through superacid catalysis, proving that it has great application potential in anion exchange membranes. At the same time, the British "Polymer Chemistry" (Polym. Chem., 2017, 8, 1381-1392) reported a method for preparing a polybenzimidazole anion exchange membrane containing dimethylcobalt cyclopentadienyl cation, that is, 1,1'-dimethyl dimethylcobalt cyclopentadienyl oxidized by potassium permanganate to 1,1'-dicarboxy dimethylcobalt cyclopentadienyl. The two upper and lower pentyl rings of this monomer each have a carboxyl group and can be polymerized with benzimidazole in a microwave reactor. However, the preparation conditions of the raw material 1,1'-dimethyl dimethylcobalt cyclopentadienyl used in this preparation process are harsh and relatively expensive, which is not suitable for large-scale industrial applications. Summary of the invention

[0004] In order to improve the shortcomings and deficiencies of the above-mentioned prior art, the present invention provides a method for preparing an anion exchange membrane with a simple preparation method, cheap and readily available raw materials, and suitable for large-scale commercial production. The prepared anion exchange membrane has high conductivity and low production cost.

[0005] In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions:

[0006] The ferrocene derivative anion exchange membrane is characterized in that its general structural formula contains a repeating unit as shown in formula (1):

[0007]

[0008] In the formula, n is the degree of polymerization and m is 2, 4, or 6.

[0009] Furthermore, the anion exchange membranes of ferrocene derivatives with different side chain lengths have structural formulas as shown in Formula I, Formula II and Formula III respectively:

[0010]

[0011]

[0012] Another object of the present invention is to provide a method for preparing a ferrocene derivative anion exchange membrane, comprising the following steps:

[0013] Step 1: dissolving a polyisocyanate biphenyl polymer and a bromoalkyl alcohol in a polar solvent, adding anhydrous K2CO3 to the solution, heating and stirring the solution under anhydrous and oxygen-free conditions for reaction, then pouring the solution into a large amount of acetone for precipitation, and washing the solution multiple times to obtain a first product; the molar ratio of the polyisocyanate biphenyl to the bromoalkyl alcohol is 1:1, and the volume of the acetone is at least 10 times the volume of the polar solvent;

[0014] Step 2: dissolving the first product, sodium hydride, tetrabutylammonium bromide (TBAB) and cyclopentadienyl-iron-toluene hexafluorophosphate bromide (Br-[Cp-Fe-toluene]PF6) in a polar solvent, heating and stirring to react under anhydrous and oxygen-free conditions, then pouring into a large amount of acetone to precipitate, and washing multiple times to obtain a second product;

[0015] Step 3: dissolving the second product in a polar solvent to obtain a membrane-forming solution after the second product is completely dissolved, wherein the membrane-forming solution contains 1.5% to 2% by weight of the second product;

[0016] Step 4: The membrane-forming solution obtained in step 3 is cast into a membrane by a casting method, so as to obtain a ferrocene derivative anion exchange membrane.

[0017] Furthermore, the preparation method of Br-[Cp-Fe-toluene]PF6 is as follows: under nitrogen protection, 1 mmol [Cp-Fe-toluene]PF6 and 10 ml 1,2-dichloroethane are added to a three-necked flask, and after complete dissolution, 1 mmol N-bromosuccinimide (NBS) and 0.1 mmol azobisisobutylcyanide (AIBN) are added, and after stirring at 65° C. for 4 to 5 hours, the mixture is poured into ether for precipitation, filtered and washed to obtain Br-[Cp-Fe-toluene]PF6.

[0018] The beneficial effects of the present invention are:

[0019] 1. The present invention polymerizes biphenyl and indigo carmine under the catalysis of superacid. Different from the traditional high-temperature polymerization reaction, the polymerization temperature of this reaction is room temperature and the reaction time is short.

[0020] 2. The present invention is different from the traditional method of using organic cations as the hydroxide transport group of the anion exchange membrane, but explores the use of organic metal cations with good stability as the hydroxide transport group;

[0021] 3. The present invention is different from the conventional anion exchange membrane without side chains. The long alkyl side chain effectively improves the ion conductivity of the anion exchange membrane.

[0022] 4. The greatest advantage of the present invention is that anion exchange membranes with different side chain lengths containing ferrocene derivatives are prepared, further exploring the application potential of organic metal cations in anion exchange membranes. At the same time, the introduction of flexible side chains promotes the formation of hydrophilic-hydrophobic phase separation inside the anion exchange membrane, which greatly improves the ion conductivity of the anion exchange membrane compared to anion exchange membranes without side chain structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of the PIB-BE-[Cp-Fe-toluene] anion exchange membrane obtained in Example 1 of the present invention;

[0024] Figure 2 The relationship between the conductivity and temperature of the anion exchange membranes of ferrocene derivatives with different side chains obtained in Examples 1-3 of the present invention is shown in FIG. 1. The horizontal axis in the figure is temperature (°C), and the vertical axis is conductivity (mS / cm). DETAILED DESCRIPTION

[0025] In order to further understand the present invention, preferred embodiments of the present invention are described in further detail below in conjunction with examples.

[0026] Example 1, Method for preparing PIB-BE-[Cp-Fe-toluene] anion exchange membrane

[0027] (1) Weigh 1 g of PIB and dissolve it in 20 ml of N,N-dimethylformamide at 40°C under stirring to obtain a light yellow transparent solution;

[0028] (2) adding anhydrous potassium carbonate to the above solution at a molar ratio of PIB:K2CO3=1:2, and adding BE solution to the above solution at a molar ratio of PIB:BE=1:3, stirring continuously at 65°C for 48 hours, then pouring into a large amount of acetone to precipitate, washing several times, and drying in a 40°C vacuum oven to obtain PIB-BE as a white solid;

[0029] (3) Weigh 0.25 g of PIB-BE and dissolve it in 5 ml of N,N-dimethylformamide at 40 °C under stirring to obtain a light yellow transparent solution;

[0030] (4) NaH and TBAB were added to the above solution at a molar ratio of PIB-BE:NaH:TBAB=1:1:0.1 at 0°C, and Br-[Cp-Fe-toluene]PF6 solution was added to the above solution at a molar ratio of PIB-BE:Br-[Cp-Fe-toluene]PF6=1:3, stirred at 40°C for 4 hours, then poured into a large amount of acetone for precipitation, washed several times, and dried in a vacuum oven at 40°C;

[0031] (5) Weigh 0.1 g of PIB-BE-[Cp-Fe-toluene] polymer and dissolve it in 5 g of N,N-dimethylformamide at room temperature to obtain a casting solution with a mass fraction of 2% of PIB-BE-[Cp-Fe-toluene];

[0032] (6) The casting solution is poured onto a glass plate by a casting method, wherein the film forming process is to dry the solvent at 60°C for 6 hours.

[0033] (7) The composite membrane was immersed in a 2 mol / L NH4Cl solution at 60°C for 48 hours to exchange for Cl - type, and then immersed in 1 mol / L NaOH solution at room temperature for 24 hours to exchange into OH - Type, rinse the membrane surface with deionized water until the pH value is neutral, and obtain OH - Type anion exchange membrane containing ferrocene derivatives.

[0034] Example 2, Method for preparing PIB-CB-[Cp-Fe-toluene] anion exchange membrane

[0035] (1) Weigh 1 g of PIB and dissolve it in 20 ml of N,N-dimethylformamide at 40°C under stirring to obtain a light yellow transparent solution;

[0036] (2) adding anhydrous potassium carbonate to the above solution at a molar ratio of PIB:K2CO3=1:2, and adding CB solution to the above solution at a molar ratio of PIB:CB=1:3, stirring continuously at 80°C for 48 hours, then pouring into a large amount of acetone to precipitate, washing several times, and drying in a 40°C vacuum oven to obtain a white solid;

[0037] (3) Weigh 0.25 g of PIB-CB and dissolve it in 5 ml of N,N-dimethylformamide at 40°C under stirring to obtain a colorless light yellow transparent solution;

[0038] (4) NaH and TBAB were added to the above solution at a molar ratio of PIB-CB:NaH:TBAB=1:1:0.1 at 0°C, and Br-[Cp-Fe-toluene]PF6 solution was added to the above solution at a molar ratio of PIB-CB:Br-[Cp-Fe-toluene]PF6=1:3, stirred at 40°C for 4 hours, then poured into a large amount of acetone for precipitation, washed several times, and dried in a vacuum oven at 40°C;

[0039] (5) Weigh 0.1 g of PIB-CB-[Cp-Fe-toluene] polymer and dissolve it in 5 g of N,N-dimethylformamide at room temperature to obtain a casting solution with a mass fraction of 2% of PIB-CB-[Cp-Fe-toluene];

[0040] (6) The casting solution is poured onto a glass plate by a casting method, wherein the film forming process is to dry the solvent at 60°C for 6 hours.

[0041] (7) The composite membrane was immersed in a 2 mol / L NH4Cl solution at 60°C for 48 hours to exchange for Cl - type, and then immersed in 1 mol / L NaOH solution at room temperature for 24 hours to exchange into OH - Type, rinse the membrane surface with deionized water until the pH value is neutral, and obtain OH - Type anion exchange membrane containing ferrocene derivatives.

[0042] Example 3, Method for preparing PIB-BH-[Cp-Fe-toluene] anion exchange membrane

[0043] (1) Weigh 1 g of PIB and dissolve it in 20 ml of N,N-dimethylformamide at 40°C under stirring to obtain a light yellow transparent solution;

[0044] (2) adding anhydrous potassium carbonate to the above solution at a molar ratio of PIB:K2CO3=1:2, and adding BE solution to the above solution at a molar ratio of PIB:BH=1:3, stirring continuously at 65°C for 48 hours, then pouring into a large amount of acetone to precipitate, washing several times, and drying in a 40°C vacuum oven to obtain a white solid;

[0045] (3) Weigh 0.25 g of PIB-BH and dissolve it in 5 ml of N,N-dimethylformamide at 40 °C with stirring to obtain a light yellow transparent solution;

[0046] (4) NaH and TBAB were added to the above solution at a molar ratio of PIB-BH:NaH:TBAB = 1:1:0.1 at 0°C, and Br-[Cp-Fe-toluene]PF6 solution was added to the above solution at a molar ratio of PIB-BH:Br-[Cp-Fe-toluene]PF6 = 1:3, stirred at 40°C for 4 hours, then poured into a large amount of acetone for precipitation, washed several times, and dried in a vacuum oven at 40°C;

[0047] (5) Weigh 0.1 g of PIB-BH-[Cp-Fe-toluene] polymer and dissolve it in 5 g of N,N-dimethylformamide at room temperature to obtain a casting solution with a mass fraction of 2% of PIB-BH-[Cp-Fe-toluene];

[0048] (6) The casting solution is poured onto a glass plate by a tape casting method, wherein the film forming process is to dry the solvent at 60°C for 6 hours.

[0049] (7) The composite membrane was immersed in a 2 mol / L NH4Cl solution at 60°C for 48 hours to exchange for Cl - type, and then immersed in 1 mol / L NaOH solution at room temperature for 24 hours to exchange into OH - Type, rinse the membrane surface with deionized water until the pH value is neutral, and obtain OH - Type anion exchange membrane containing ferrocene derivatives.

[0050] The description of the above embodiments is only used to help illustrate the implementation method and features of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made to the present invention without departing from the principles of the present invention. These improvements and modifications are also covered by the protection scope of the claims of the present invention.

Claims

1. A ferrocene derivative anion exchange membrane, characterized in that: Its general structure contains the following repeating units: Wherein, n is the degree of polymerization, and m is an integer ≥1.

2. The ferrocene derivative anion exchange membrane according to claim 1, characterized in that: m is 2, 4, or 6.

3. The ferrocene derivative anion exchange membrane according to claim 1, characterized in that: The cationic group adopts cyclopentadienyl-iron-toluene cation; The anion exchange membranes of ferrocene derivatives with different side chain lengths have structural formulas as shown in Formula I, Formula II and Formula III respectively:

4. The method for preparing a ferrocene derivative anion exchange membrane according to any one of claims 1 to 3, characterized in that: The steps include: Step 1: dissolving a polyisocyanate biphenyl polymer and a bromoalkyl alcohol in a polar solvent, adding anhydrous K2CO3 to the solution, heating and stirring the solution under anhydrous and oxygen-free conditions for reaction, then pouring the solution into a large amount of acetone for precipitation, washing the solution several times and drying the solution to obtain a first product; the molar ratio of the polyisocyanate biphenyl to the bromoalkyl alcohol is 1:1, and the volume of the acetone is at least 10 times the volume of the polar solvent; Step 2: dissolving the first product, sodium hydride, tetrabutylammonium bromide (TBAB) and brominated cyclopentadienyl-iron-toluene hexafluorophosphate (Br-[Cp-Fe-toluene]PF6) salt in a polar solvent, heating and stirring to react under anhydrous and oxygen-free conditions, then pouring into a large amount of acetone to precipitate, washing multiple times and drying to obtain a second product; Step 3: dissolving the second product in a polar solvent to obtain a membrane-forming solution after the second product is completely dissolved, wherein the membrane-forming solution contains 1.5% to 2% by weight of the second product; Step 4: The membrane-forming solution obtained in step 3 is cast into a membrane by a casting method, so as to obtain a ferrocene derivative anion exchange membrane.

5. The method for preparing a ferrocene derivative anion exchange membrane according to claim 4, characterized in that: The preparation method of Br-[Cp-Fe-toluene]PF6 is as follows: under nitrogen protection, cyclopentadienyl-iron-toluene hexafluorophosphate ([Cp-Fe-toluene]PF6) is dissolved in 1,2-dichloroethane in a three-necked flask, and after complete dissolution, N-bromosuccinimide (NBS) and azobisisobutylcyanide (AIBN) are added, and after stirring at 65°C for 4 to 5 hours, the mixture is poured into ether for precipitation, filtered and washed to obtain Br-[Cp-Fe-toluene]PF6.

6. The method for preparing a ferrocene derivative anion exchange membrane according to claim 4, characterized in that: The bromoalkyl alcohols are 2-bromoethanol (BE), 4-chlorobutanol (CB) and 6-bromohexanol (BH).

7. The method for preparing a ferrocene derivative anion exchange membrane according to claim 4, characterized in that: The polar solvent is N,N-dimethylformamide.

8. The method for preparing a ferrocene derivative anion exchange membrane according to claim 4, characterized in that: In step 1, the heating temperature is 65° C. and the stirring time is 48 hours. In step 2, the heating temperature is 40° C. and the stirring time is 4 hours.

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