Aryl piperidine anion exchange membrane containing dication center and preparation method thereof

Abstract

The invention discloses a double-cation-center polyaryl piperidine anion exchange membrane and a preparation method thereof, and belongs to the technical field of high polymer materials, and the preparation method comprises the following steps: preparing a poly (biaryl compound-piperidone) polymer PAP; dissolving the obtained PAP in N-methyl pyrrolidone, adding 3-bromopropyl triphenyl phosphonium bromide into the solution, putting the mixture into a heating jacket, heating to 75 DEG C, keeping for 24 hours, cooling to room temperature after heating is finished, adding quantitative CH3I into the system, putting a reaction bottle filled with reaction liquid into a dark closed environment, stirring for 12 hours, filtering under reduced pressure, and performing vacuum drying to obtain the target product. Finally, casting the solution on clean glass, and drying to obtain PAP-P-x; and stripping the obtained membrane, and immersing the membrane in a NaOH solution for ion exchange to obtain the OH-form anion exchange membrane. According to the anion exchange membrane, piperidone is used as a branched chain structure on the basis of retaining a main chain aromatic structure, and then a P cation center is introduced through modification so as to expect to obtain double anion transmission efficiency; according to the preparation method disclosed by the invention, a new cation center is introduced to react with a main chain, so that the operation is simple, the conductivity is effectively enhanced, the swelling of a polymer chain is also effectively limited, and the steric effect can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a polyaryl piperidine anion exchange membrane with a double cation center and a preparation method thereof. Background Art

[0002] With the rapid development of society, ion exchange membranes occupy an important position in the field of membrane technology and provide considerable help in our daily lives. Ion exchange membrane technology plays an important role in seawater, brackish water, hydrogen energy, electrochemical industry, electrolytic metallurgy, seawater desalination, food, medicine and other fields. In recent years, the rapid development of new chemical power sources and the application of anion exchange membranes (AEMs) in liquid flow energy storage, electrolysis, fuel cells, new supercapacitors and other fields have attracted increasing attention. AEMs play an important role in conducting hydroxide ions and blocking fuel gas and oxygen in fuel cells. They have the advantages of good dynamic reactivity, use of low-cost and platinum-free catalysts, good material stability, durability and inhibition of fuel permeation. It can also convert chemical energy into electrical energy without producing any waste, so it is a pollution-free green energy device. In the electrolysis of water by AEMs, the use of non-precious metal catalysts can reduce costs. Enapter, an energy technology company, has also initially completed the demonstration application of AEM water electrolyzer (AEMWE). However, the alkaline stability and device stability of AEMWE at 80°C are still less than 5000h, so it is still difficult to achieve large-scale commercial application. Therefore, the alkaline stability of AEMs will continue to be a key research direction in the future.

[0003] AEMs are polymer membranes containing alkaline active groups that selectively permeate anions. They are also called ion-selective permeable membranes. AEMs can be divided into three parts: a polymer backbone with fixed groups, a positively charged active group, and anions that move freely in the active group. The "channel" for anion migration is surrounded by a main chain connected by the polymer backbone and a side chain formed by a cationic group connected by a chemical bond, allowing the selective transmission of anions and the blocking of cations. AEMs generally require high conductivity, good thermal stability, mechanical properties, and alkali resistance. The membrane matrix material of AEM determines the thermal stability and mechanical properties of the membrane. At the same time, different functional groups and quantities determine the conductivity of the membrane. Together (especially the functional groups) they determine the chemical stability of the membrane (i.e., alkali resistance stability).

[0004] The cations evolved from quaternary ammonium (QA), quaternary phosphonium, tertiary sulfonic acid, aromatic QA and aliphatic heterocyclic cations. Among these aromatic QA cations, benzyl and pyridinium cations have poor alkali stability and are prone to nucleophilic substitution and Hoffman degradation reactions under alkaline conditions. Aliphatic cyclic cations exhibit excellent alkali stability. Cyclic cations provide a technology for improving the stability of cations due to their large steric resistance. Summary of the invention

[0005] In order to improve the conductivity with maximum efficiency and overcome the problems existing in the prior art such as the elimination reaction of β-C in an alkaline environment destroying the AEM structure and poor mechanical properties, the present invention provides a polyaryl piperidine anion exchange membrane containing a double cation center and a preparation method thereof. The anion exchange membrane retains the main chain aromatic structure and uses piperidone as a side chain structure, and then introduces a P cation center through modification in the hope of obtaining a double anion transmission efficiency. The preparation method of the present invention is simple to operate by introducing a new cation center to react with the main chain, which not only effectively enhances the conductivity, but also effectively limits the swelling of the polymer chain and reduces the steric effect.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for preparing a polyarylpiperidine anion exchange membrane containing a double cationic center comprises the following steps:

[0008] Step 1: Preparation of poly(biaryl compound-piperidone) polymer PAP;

[0009] It is prepared by continuous polycondensation of biaryl compounds and piperidone under the catalysis of strong acid;

[0010] Step 2: Preparation of poly(biaryl compound-piperidone) anion exchange membrane;

[0011] The poly(biaryl compound-piperidone) polymer prepared in step 1 is dissolved in N-methylpyrrolidone, 3-bromopropyltriphenylphosphine bromide is added to the solution, the mixture is placed in a heating mantle and heated to 75°C, maintained for 24 hours, cooled to room temperature after heating, and then a certain amount of CH3I is added to the system, the reaction bottle containing the reaction solution is placed in a dark and closed environment, stirred for 12 hours, filtered under reduced pressure, and finally the solution is cast on a clean glass and dried to obtain PAP-Px, wherein x is the molar ratio of 3-bromopropyltriphenylphosphine bromide to the poly(biaryl compound-piperidone) polymer; the obtained membrane is peeled off, immersed in a NaOH solution for ion exchange, and OH is obtained. - Form anion exchange membrane.

[0012] Furthermore, the biaryl compound in step 1 is biphenyl, p-terphenyl or m-terphenyl.

[0013] Furthermore, the preparation of the poly(biaryl compound-piperidone) polymer in step 1 is specifically carried out as follows:

[0014] The biaryl compound and N-methyl-4-piperidone are dissolved in a solvent in a certain proportion, the reaction bottle containing the above reaction solution is immersed in an ice water bath, and a certain amount of a mixed solution of trifluoroacetic acid and trifluoromethanesulfonic acid is added dropwise at 0°C; then, the temperature is maintained and stirred for a certain time, and the obtained viscous dark solution is poured into a K2CO3 solution to neutralize the excess acid to obtain a light yellow solid polymer; the polymer is ground into powder and immersed in a K2CO3 solution for a certain time; finally, the polymer is washed with deionized water for multiple times until it is neutral, and dried to obtain a poly (biaryl compound-piperidone) polymer (PAP).

[0015] Furthermore, the molar ratio of the biaryl compound to N-methyl-4-piperidone is in the range of 1:1-1:1.3.

[0016] Furthermore, the volume ratio of trifluoroacetic acid to trifluoromethanesulfonic acid is 1:6-1:9.

[0017] Furthermore, the solvent is dichloromethane.

[0018] Furthermore, the stirring time is in the range of 3-6 hours, and the soaking time is in the range of 24-48 hours.

[0019] Furthermore, the mass volume ratio of the poly(biaryl compound-piperidone) polymer to N-methylpyrrolidone is 0.9 g:20-26 ml.

[0020] Furthermore, the sum of the molar amounts of CH3I and 3-bromopropyltriphenylphosphonium bromide is equal to the molar amount of the biaryl compound; and x is 10-25%.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] The invention discloses a polyaryl piperidine anion exchange membrane containing a double cation center and a preparation method thereof. In terms of the main chain, when the anion exchange membrane is synthesized by polymerization reaction with piperidone, the aromatic structure used is a biaryl compound; in terms of the side chain, the substances used are piperidone and 3-bromopropyltriphenylphosphonium bromide, and the substances that need to be protected are (aromatic or aliphatic) P cation center homologues with other substituents, and quaternary ammonium base substances after piperidone is methylated by methyl iodide.

[0023] In summary, by introducing 3-bromopropyltriphenylphosphonium bromide as a newly added cationic center, the ion exchange capacity (IEC) and anion transmission efficiency are improved, the swelling of the membrane is effectively inhibited, and the mechanical properties of the membrane are improved; the (double cationic center) polyaryl piperidine anion exchange membrane without ether bonds and having a microphase separation structure prepared by the present invention has excellent alkali resistance, ion conductivity and good mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0025] Figure 1 This is a hydrogen nuclear magnetic resonance spectrum of the polyarylpiperidine anion exchange membrane prepared in Example 1;

[0026] Figure 2 A schematic diagram of the ion conductivity of the anion exchange membrane prepared in Example 1 of the present invention at different temperatures;

[0027] Figure 3 This is a hydrogen nuclear magnetic resonance spectrum of the polyarylpiperidine anion exchange membrane prepared in Example 2 of the present invention;

[0028] Figure 4 This is a schematic diagram of the ion conductivity of the anion exchange membrane prepared in Example 2 of the present invention at different temperatures. DETAILED DESCRIPTION

[0029] In order to clearly and completely describe the technical solution and its specific working process of the present invention, the specific implementation methods of the present invention are as follows in conjunction with the accompanying drawings of the specification:

[0030] Example 1

[0031] This embodiment provides a method for preparing a polyarylpiperidine anion exchange membrane containing a dicationic center, which specifically comprises the following steps:

[0032] Step 1: Preparation of poly(biphenyl-piperidone) polymer;

[0033] Poly(biphenyl-piperidone) polymer is prepared by continuous polycondensation of biphenyl and piperidone under the catalysis of strong acid. First, biphenyl (5.0 g) and N-methyl-4-piperidone (4.5 mL) were dissolved in dichloromethane (15 mL). Subsequently, the reaction bottle was immersed in an ice-water bath, and trifluoroacetic acid (TFA, 3.0 mL) and trifluoromethanesulfonic acid (TFSA, 27.0 mL) were added dropwise at 0°C. Then, the temperature was maintained and stirred for another 5 hours, and the obtained viscous dark solution was slowly poured into a 1 mol / L K2CO3 solution to neutralize the excess acid to obtain a light yellow solid polymer. The polymer was ground into powder and soaked in a K2CO3 solution for 24 hours. Finally, the polymer was washed with deionized water several times until neutral, and dried to obtain a poly(biphenyl-piperidone) polymer (PAP);

[0034] Step 2: Preparation of poly(biphenyl-piperidone) anion exchange membrane;

[0035] PAP (0.9 g) polymer was dissolved in 25 mL of NMP, and 0.247 g of 3-bromopropyltriphenylphosphonium bromide was added. The mixture was placed in a heating mantle and heated to 75°C for 24 h. After heating, it was cooled to room temperature. 0.4 mL of CH3I was added to the system. The reaction bottle was placed in a dark and closed environment, stirred at room temperature for 12 h, filtered under reduced pressure, and finally the solution was cast on a clean glass and dried at 80°C to obtain PAP-P-20%, where 20% is the molar ratio of 3-bromopropyltriphenylphosphonium bromide. The obtained membrane was peeled off and immersed in a 1 mol / L NaOH solution for ion exchange to obtain OH - Form anion exchange membrane.

[0036] The reaction equation is as follows:

[0037]

[0038] like Figure 1 As shown in the H NMR spectrum, it can be seen from the figure that the characteristic peaks of H on biphenyl and H on the aromatic P reagent appear at 7.38-7.91ppm, and the characteristic peaks of H3 and H4 in piperidine appear at 3.28ppm and 2.67ppm. The characteristic peak of methyl H5 appears at 3.35ppm, and the characteristic peaks of branched methylene H6, H7 and H8 appear at 1.73ppm, 1.90ppm and 2.13ppm. The prepared anion exchange membrane has an ion conductivity of 152mS / cm at 80°C, a water absorption rate of 21.1%, a swelling rate of 46.3%, and a conductivity of 95.1% of the initial value after being immersed in 5M sodium hydroxide solution for 30 days, a tensile strength of 51Mpa, and an elongation at break of 17.7%.

[0039] Example 2

[0040] This embodiment provides a method for preparing a polyarylpiperidine anion exchange membrane containing a dicationic center, which specifically comprises the following steps:

[0041] Step 1: Preparation of poly (p-terphenyl-piperidone) polymer;

[0042] Poly(p-terphenyl-piperidone) polymer is prepared by continuous polycondensation of p-terphenyl and piperidone under the catalysis of strong acid. First, p-terphenyl (5.0 g) and N-methyl-4-piperidone (3.4 mL) were dissolved in dichloromethane (13 mL). Subsequently, the reaction flask was immersed in an ice-water bath, and trifluoroacetic acid (TFA, 2.0 mL) and trifluoromethanesulfonic acid (TFSA, 18.0 mL) were added dropwise at 0°C. Then, the temperature was maintained and stirred for another 5 hours, and the obtained viscous dark solution was slowly poured into a 1 mol / L K2CO3 solution to neutralize the excess acid to obtain a light yellow solid polymer. The polymer was ground into powder and soaked in a K2CO3 solution for 24 hours. Finally, the polymer was washed with deionized water several times until neutralized and dried to obtain a poly(p-terphenyl-piperidone) polymer (PTP);

[0043] Step 2: Preparation of poly (p-terphenyl-piperidone) anion exchange membrane;

[0044] PTP (0.9 g) polymer was dissolved in 25 mL of NMP, and 0.195 g of 3-bromopropyltriphenylphosphonium bromide was added. The mixture was placed in a heating mantle and heated to about 75°C for 24 h. After heating, it was cooled to room temperature, and 0.4 mL of CH3I was added to the system. The reaction bottle was placed in a dark and closed environment, stirred at room temperature for 12 h, filtered under reduced pressure, and finally the solution was cast on a clean glass and dried at 80°C to obtain PTP-P-20%, where 20% is the molar ratio of 3-bromopropyltriphenylphosphonium bromide. The obtained membrane was peeled off and immersed in a 1 mol / L NaOH solution for ion exchange to obtain OH - Form anion exchange membrane.

[0045] The reaction equation is as follows:

[0046]

[0047] like Figure 3 For the H NMR spectrum analysis of anion exchange membrane, Figure 4 The anion exchange membrane prepared as shown has an ion conductivity of 176.6 mS / cm at 80°C, a water absorption rate of 21.1%, a swelling rate of 8.9%, and after being immersed in a 5M sodium hydroxide solution for 30 days, the conductivity is still 96.1% of the initial value, the tensile strength is 77 MPa, and the elongation at break is 18.1%.

Claims

1. A method for preparing a polyarylpiperidine anion exchange membrane containing a dicationic center, characterized in that: The specific steps include: Step 1: Preparation of poly(biaryl compound-piperidone) polymer PAP; It is prepared by continuous polycondensation of biaryl compounds and piperidone under the catalysis of strong acid; Step 2: Preparation of poly(biaryl compound-piperidone) anion exchange membrane; The poly(biaryl compound-piperidone) polymer prepared in step 1 is dissolved in N-methylpyrrolidone, 3-bromopropyltriphenylphosphine bromide is added to the solution, the mixture is placed in a heating mantle and heated to 75°C, maintained for 24 hours, cooled to room temperature after heating, and then a certain amount of CH3I is added to the system, the reaction bottle containing the reaction solution is placed in a dark and closed environment, stirred for 12 hours, filtered under reduced pressure, and finally the solution is cast on a clean glass and dried to obtain PAP-Px, wherein x is the molar ratio of 3-bromopropyltriphenylphosphine bromide to the poly(biaryl compound-piperidone) polymer; the obtained membrane is peeled off, immersed in a NaOH solution for ion exchange, and OH is obtained. - Form anion exchange membrane.

2. The method for preparing a polyarylpiperidine anion exchange membrane containing a dicationic center as claimed in claim 1, characterized in that: In step 1, the biaryl compound is biphenyl, p-terphenyl or m-terphenyl.

3. The method for preparing a polyarylpiperidine anion exchange membrane containing a dicationic center as claimed in claim 1, characterized in that: The preparation of the poly(biaryl compound-piperidone) polymer in step 1 is carried out in the following specific steps: The biaryl compound and N-methyl-4-piperidone are dissolved in a solvent in a certain proportion, the reaction bottle containing the above reaction solution is immersed in an ice water bath, and a certain amount of a mixed solution of trifluoroacetic acid and trifluoromethanesulfonic acid is added dropwise at 0°C; then, the temperature is maintained and stirred for a certain time, and the obtained viscous dark solution is poured into a K2CO3 solution to neutralize the excess acid to obtain a light yellow solid polymer; the polymer is ground into powder and immersed in a K2CO3 solution for a certain time; finally, the polymer is washed with deionized water for multiple times until it is neutral, and dried to obtain a poly (biaryl compound-piperidone) polymer (PAP).

4. The method for preparing a polyarylpiperidine anion exchange membrane containing a dicationic center according to claim 1, characterized in that: The molar ratio of the biaryl compound to N-methyl-4-piperidone is in the range of 1:1 to 1:1.

3.

5. The method for preparing a polyarylpiperidine anion exchange membrane containing a dicationic center according to claim 1, characterized in that: The volume ratio of trifluoroacetic acid to trifluoromethanesulfonic acid is 1:6-1:

9.

6. The method for preparing a polyarylpiperidine anion exchange membrane containing a dicationic center according to claim 1, characterized in that: The solvent is dichloromethane.

7. The method for preparing a polyarylpiperidine anion exchange membrane containing a dicationic center according to claim 1, characterized in that: The stirring time is in the range of 3-6 hours, and the soaking time is in the range of 24-48 hours.

8. The method for preparing a polyarylpiperidine anion exchange membrane containing a dicationic center according to claim 1, characterized in that: The mass volume ratio of the poly(biaryl compound-piperidone) polymer to N-methylpyrrolidone is 0.9 g:20-26 ml.

9. The method for preparing a polyarylpiperidine anion exchange membrane containing a dicationic center according to claim 1, characterized in that: The sum of the molar amounts of CH3I and 3-bromopropyltriphenylphosphonium bromide is equal to the molar amount of the biaryl compound; and x is 10-25%.

10. A polyarylpiperidine anion exchange membrane containing a dicationic center, characterized in that: The method is prepared by any one of claims 1 to 9.

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