CN110739478A

CN110739478A - Preparation method of long-short side chain blended anion exchange membranes

Info

Publication number: CN110739478A
Application number: CN201911079016.5A
Authority: CN
Inventors: 张凤祥; 周芮霆; 贾亚斌; 马玲玲; 李旅; 白雷
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2019-11-07
Filing date: 2019-11-07
Publication date: 2020-01-31
Anticipated expiration: 2039-11-07
Also published as: CN110739478B

Abstract

The invention provides a preparation method of long and short side chain blending type anion exchange membranes, which belongs to the field of fuel cell solid electrolyte membranes.

Description

Preparation method of long-short side chain blended anion exchange membranes

Technical Field

The invention belongs to the field of fuel cell solid electrolyte membranes, and particularly relates to a preparation method of long-short side chain blended anion exchange membranes.

Background

Fuel cells have received a lot of attention from as environment-friendly energy technology, it is well known that Anion Exchange Membrane Fuel Cells (AEMFCs) have many unique advantages over Proton Exchange Membrane Fuel Cells (PEMFCs). PEMFCs rely heavily on noble metal catalysts (e.g., Pt) to minimize corrosion, while the basic conditions of AEMFCs allow the use of non-noble metals (e.g., Ag, Ni, Fe) as catalysts, thereby reducing the cost of AEMFCs.

The AEM is used as a core component of an AEMFC of an anion exchange membrane fuel cell, not only needs to separate an oxidant and a fuel from an anode chamber and a cathode chamber, but also is used as an intermediate medium for conducting hydroxide ions to form a whole loop, so that the AEM plays an important role in the performance and the service life of the fuel cell. Therefore, in order to realize the commercial application of the fuel cell, it is necessary to prepare an anion exchange membrane having excellent performance. The current commercial membranes have the problems of low hydroxide ion conductivity and poor chemical stability, and cannot meet the requirements of fuel cells. While high hydroxide conductivity, low swelling ratio and good alkali stability are the main requirements for AEMs to achieve durability and high energy density for fuel cells. The most efficient method for improving the conductivity is to construct a microphase separation structure to realize continuous ion channels, and two common methods are to design a novel polymer main chain or perform side chain grafting. Gao L et al grafted long side chains on PPO to improve the microphase separation structure of the membrane, and the prepared membrane has IEC of 1.83mmol g^-1The conductivity at room temperature is as high as42mS cm^-1。

The flexible side chains enable cationic groups to be more easily aggregated, so that larger ion clusters can be formed to form continuous ion channels, and further the conductivity is improved.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides long-short side chain blended anion-exchange membranes and a preparation method thereof.

The technical scheme adopted by the invention is as follows:

kinds of long and short side chain blended anion exchange membrane, using polyphenylether as polymer base, using 6-bromocaproyl chloride and PPO to make acylation reaction to connect with longer side chain, reducing carbonyl on long side chain, at the same time using NBS and PPO to make bromination reaction to obtain PPO containing short chain.

The structure of the blended anion-exchange membrane is shown as follows:

a preparation method of long-short side chain blended anion exchange membranes comprises the steps of acylation of PPO, bromination of PPO, reduction of carbonyl, quaternization of gradient side chain polymers, film formation and alkalization, and comprises the following specific steps:

(1) preparation of acylated polyphenylene ethers

Firstly, adding polyphenyl ether into dichloromethane serving as a solvent at room temperature, wherein 0.5-1.5g of polyphenyl ether is added into every 10ml of dichloromethane, and stirring until the solution is clear to obtain a polyphenyl ether solution. Then, under the protection of nitrogen, adding anhydrous aluminum trichloride into a solvent dichloromethane, and dropwise adding 6-bromohexanoyl chloride under the condition of ice-water bath, wherein 0.5-0.7 g of anhydrous aluminum trichloride is correspondingly added into every 10ml of dichloromethane, and the molar ratio of the anhydrous aluminum trichloride to the 6-bromohexanoyl chloride is 1: 1; stirring for 10min, adding the dissolved polyphenyl ether solution, and reacting at room temperature for 1.5-3 h to obtain a tan solution. And finally, pouring the solution into lower alcohol to precipitate a solid polymer, washing the solid polymer by using ethanol, and drying the solid polymer in vacuum to obtain the acylated polyphenylene oxide (PPO-COC5H 10-Br).

(2) Reduction of side chain carbonyl groups of polyphenylene ethers

Firstly, adding the acylated polyphenyl ether prepared in the step (1) into a reaction vessel, adding dewatered 1, 2-dichloroethane as a solvent under the protection of nitrogen, stirring until the solution is clear, adding excess trifluoroacetic acid and excess triethylsilane, and reacting for 36-54h at 80 ℃ under magnetic stirring. Next, the pH of the reaction solution was adjusted to 8 with 5mol/L NaOH. And finally, removing 1, 2-dichloroethane by rotary evaporation, separating out the solid polymer in water, performing suction filtration to obtain the solid polymer, washing and soaking the solid polymer for multiple times by using lower alcohol, and performing vacuum drying to obtain the carbonyl-reduced polyphenyl ether material.

The molar ratio of carbonyl of the acylated polyphenylene ether to trifluoroacetic acid and triethylsilane is 1: 100-300: 5 to 15.

(3) Bromination of polyphenylene oxide (PPO)

First, the polyphenylene ether is added to the solvent chlorobenzene, wherein 0.5-1.5g polyphenylene ether material is added per 10mL chlorobenzene. And secondly, heating to 80 ℃, adding Azobisisobutyronitrile (AIBN) and N-bromosuccinimide (NBS), and heating to 125 ℃ for reaction for 2-4 hours. And finally, pouring the solution after the reaction into lower alcohol to precipitate a solid polymer, washing the solid polymer by using methanol, and drying the solid polymer in vacuum to obtain the brominated polyphenylene oxide.

The molar ratio of the PPO to the N-bromosuccinimide (NBS) to the Azobisisobutyronitrile (AIBN) is 1: 0.6-1: 0.3-0.5.

(4) Quaternary amination of polymers

And (3) dissolving the polyphenyl ether material prepared in the step (2) and the brominated polyphenyl ether prepared in the step (3) into an organic solvent according to the mass ratio of 9:1 at room temperature, adding 0.4-0.6ml of nitrogen-containing heterocyclic groups, reacting at 30-80 ℃ for 12-48h, and carrying out quaternization on the blended polymer to obtain a polymer solution. The nitrogen heterocyclic group is N-methylmorpholine, N-methylpiperidine and N-methylpyrrole.

The mol ratio of the bromomethyl to the nitrogen-containing heterocyclic group is 1: 4-6.

(5) Cast film

And (3) placing the polymer solution prepared in the step (4) on a glass plate to form a film, and heating for 24-48h at 40-80 ℃.

(6) Anion exchange membranes by base exchange

And peeling the obtained membrane from the surface of the glass plate, soaking in 0.1-2M alkali solution for 24-48 hours, and washing off free hydroxide ions in the membrane to obtain the blending type anion exchange membrane.

The vacuum drying temperature in the step (1) is 30-100 ℃, and the drying time is 12-48 h;

the vacuum drying temperature in the step (2) is 30-100 ℃, and the drying time is 12-48 h; soaking for 12h by multi-stage alcohol.

The vacuum drying temperature in the step (3) is 30-100 ℃, and the drying time is 12-48 h;

the lower alcohol in the step (1) is or more mixed solvents in methanol, ethanol and isopropanol, the vacuum drying temperature is 30-100 ℃, and the drying time is 12-48 h;

the lower alcohol in the step (2) is or more mixed solvents in methanol, ethanol and isopropanol, the vacuum drying temperature is 30-100 ℃, and the drying time is 12-48 h;

the lower alcohol in the step (3) is or more mixed solvents in methanol, ethanol and isopropanol.

The organic solvent in the step (4) is N, N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP) or dimethyl sulfoxide (DMSO).

The invention has the beneficial effects that: according to the invention, the long-short side chain blended anion exchange membrane is adopted, so that high conductivity under low IEC can be realized, and the membrane has good chemical stability, dimensional stability and high conductivity.

Drawings

FIG. 1 is the curve of the water absorption of the long and short side chain blend films of example 1, example 2 and example 3 with temperature;

FIG. 2 is the swelling ratio of the long and short side chain blend films of example 1, example 2 and example 3 as a function of temperature.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The preparation method and properties of the blend-type anion exchange membrane according to the present invention are further illustrated in detail by the following example .

Example 1

First, 0.5g of polyphenylene ether was added to 10ml of methylene chloride at room temperature, and stirred until the solution became clear to obtain a polyphenylene ether solution. Then, under the protection of nitrogen, 0.5g of anhydrous aluminum trichloride is added into 10ml of dichloromethane, 6-bromohexanoyl chloride is dropwise added under the condition of ice-water bath, after stirring for 10min, the dissolved polyphenyl ether solution is added, and the reaction is carried out for 1.5h at room temperature, so as to obtain a tan solution. And finally, pouring the solution into lower alcohol to precipitate a solid polymer, washing the solid polymer by using ethanol, and drying the solid polymer in vacuum to obtain the acylated polyphenylene oxide (PPO-COC5H 10-Br).

Firstly, the acylated polyphenylene oxide prepared in the previous step is added into a reaction vessel, and under the protection of nitrogen, dehydrated 1, 2-dichloroethane is added as a solvent, the mixture is stirred until the solution is clear, 30ml of trifluoroacetic acid and 3ml of triethylsilane are added, and the mixture is reacted for 36 hours at 80 ℃ under the magnetic stirring. Next, the pH of the reaction solution was adjusted to 8 with 5mol/L NaOH. And finally, removing 1, 2-dichloroethane by rotary evaporation, separating out the solid polymer in water, performing suction filtration to obtain the solid polymer, washing and soaking the solid polymer for multiple times by using lower alcohol, and performing vacuum drying to obtain the carbonyl-reduced polyphenyl ether material.

First, 0.5g of polyphenylene ether was dissolved in 10ml of chlorobenzene, and after heating to 80 ℃, 0.3g of Azobisisobutyronitrile (AIBN) and 2.4g of N-bromosuccinimide (NBS) were added, and after heating to 125 ℃, reaction was carried out for 3 hours. And finally, pouring the solution after the reaction into lower alcohol to precipitate a solid polymer, washing the solid polymer by using methanol, and drying the solid polymer in vacuum to obtain the brominated polyphenylene oxide.

And (3) dissolving the polyphenyl ether material prepared in the step (2) and the brominated polyphenyl ether prepared in the step (3) in an organic solvent according to the mass ratio of 9:1 at room temperature, adding 0.4ml of N-methylpiperidine, reacting at 30 ℃ for 12h, and carrying out quaternization on the blended polymer to obtain a polymer solution.

And (3) placing the polymer solution prepared in the step (4) on a glass plate to form a film, and heating for 24 hours at 40 ℃.

And peeling the obtained membrane from the surface of the glass plate, soaking in 0.1M/L alkali solution for 24 hours, and washing off free hydroxide ions in the membrane to obtain the blending type anion exchange membrane.

Example 2

First, 1g of polyphenylene ether was added to 10ml of methylene chloride at room temperature, and stirred until the solution became clear to obtain a polyphenylene ether solution. Then, under the protection of nitrogen, 0.6g of anhydrous aluminum trichloride is added into 10ml of dichloromethane, 6-bromohexanoyl chloride is dropwise added under the condition of ice-water bath, after stirring for 10min, the dissolved polyphenyl ether solution is added, and the reaction is carried out for 2h at room temperature, so as to obtain a tan solution. And finally, pouring the solution into lower alcohol to precipitate a solid polymer, washing the solid polymer by using ethanol, and drying the solid polymer in vacuum to obtain the acylated polyphenylene oxide (PPO-COC5H 10-Br).

Firstly, the acylated polyphenylene oxide prepared in the previous step is added into a reaction vessel, and under the protection of nitrogen, dehydrated 1, 2-dichloroethane is added as a solvent, the mixture is stirred until the solution is clear, 70ml of trifluoroacetic acid and 7ml of triethylsilane are added, and the mixture is reacted for 48 hours at 80 ℃ under the magnetic stirring. Next, the pH of the reaction solution was adjusted to 8 with 5mol/L NaOH. And finally, removing 1, 2-dichloroethane by rotary evaporation, separating out the solid polymer in water, performing suction filtration to obtain the solid polymer, washing and soaking the solid polymer for multiple times by using lower alcohol, and performing vacuum drying to obtain the carbonyl-reduced polyphenyl ether material.

First, 1g of polyphenylene ether was dissolved in 10ml of chlorobenzene, and after heating to 80 ℃, 0.2g of Azobisisobutyronitrile (AIBN) and 1.2g of N-bromosuccinimide (NBS) were added, and after heating to 125 ℃, reaction was carried out for 3 hours. And finally, pouring the solution after the reaction into lower alcohol to precipitate a solid polymer, washing the solid polymer by using methanol, and drying the solid polymer in vacuum to obtain the brominated polyphenylene oxide.

And (3) dissolving the polyphenyl ether material prepared in the step (2) and the brominated polyphenyl ether prepared in the step (3) in an organic solvent according to the mass ratio of 9:1 at room temperature, adding 0.5ml of N-methylpiperidine, reacting at 50 ℃ for 30 hours, and carrying out quaternization on the blended polymer to obtain a polymer solution.

And (3) placing the polymer solution prepared in the step (4) on a glass plate to form a film, and heating for 30 hours at the temperature of 60 ℃.

And peeling the obtained membrane from the surface of the glass plate, soaking the membrane in 1M/L alkali solution for 36 hours, and washing off free hydroxide ions in the membrane to obtain the blending type anion exchange membrane.

Example 3

First, 1.5g of polyphenylene ether was added to 10ml of methylene chloride at room temperature, and stirred until the solution became clear to obtain a polyphenylene ether solution. Then, under the protection of nitrogen, 0.7g of anhydrous aluminum trichloride is added into 10ml of dichloromethane, 6-bromohexanoyl chloride is dropwise added under the condition of ice-water bath, after stirring for 10min, the dissolved polyphenyl ether solution is added, and the reaction is carried out for 3h at room temperature, so as to obtain a tan solution. And finally, pouring the solution into lower alcohol to precipitate a solid polymer, washing the solid polymer by using ethanol, and drying the solid polymer in vacuum to obtain the acylated polyphenylene oxide (PPO-COC5H 10-Br).

Firstly, the acylated polyphenylene oxide prepared in the previous step is added into a reaction vessel, 1, 2-dichloroethane with water removed is added as a solvent under the protection of nitrogen, the mixture is stirred until the solution is clear, 140ml of trifluoroacetic acid and 14ml of triethylsilane are added, and the mixture is reacted for 54 hours at 80 ℃ under the magnetic stirring. Next, the pH of the reaction solution was adjusted to 8 with 5mol/L NaOH. And finally, removing 1, 2-dichloroethane by rotary evaporation, separating out the solid polymer in water, performing suction filtration to obtain the solid polymer, washing and soaking the solid polymer for multiple times by using lower alcohol, and performing vacuum drying to obtain the carbonyl-reduced polyphenyl ether material.

First, 1.5g of polyphenylene ether was dissolved in 10ml of chlorobenzene, and after heating to 80 ℃, 0.4g of Azobisisobutyronitrile (AIBN) and 3.6g of N-bromosuccinimide (NBS) were added, and after heating to 125 ℃, reaction was carried out for 4 hours. And finally, pouring the solution after the reaction into lower alcohol to precipitate a solid polymer, washing the solid polymer by using methanol, and drying the solid polymer in vacuum to obtain the brominated polyphenylene oxide.

And (3) dissolving the polyphenyl ether material prepared in the step (2) and the brominated polyphenyl ether prepared in the step (3) in an organic solvent according to the mass ratio of 9:1 at room temperature, adding 0.6ml of N-methylpiperidine, reacting at 80 ℃ for 48 hours, and carrying out quaternization on the blended polymer to obtain a polymer solution.

And (3) placing the polymer solution prepared in the step (4) on a glass plate to form a film, and heating for 48 hours at 80 ℃.

And peeling the obtained membrane from the surface of the glass plate, soaking in 2M/L alkali solution for 48 hours, and washing off free hydroxide ions in the membrane to obtain the blended anion-exchange membrane.

FIG. 1 is the water absorption curves of the blend films of example 1, example 2 and example 3 as a function of temperature. As can be seen from fig. 1, example 3 has the highest water absorption, followed by example 2, with example 1 having the lowest water absorption. However, the water absorption of the three blend films does not change greatly with the temperature rise to 80 ℃, which shows that the three blend films have good dimensional stability.

FIG. 2 is a plot of swelling ratio of blended films of example 1, example 2 and example 3 as a function of temperature. As can be seen from FIG. 1, the swelling ratio is highest for example 3, followed by example 2, where example 1 has the lowest swelling ratio. This is because as the degree of grafting increases, the number of ion exchange groups grafted in the membrane increases, membrane swelling increases, and membrane dimensional stability is poor.

The above-mentioned embodiments only express the embodiments of the present invention, but not should be understood as the limitation of the scope of the invention patent, it should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the concept of the present invention, and these all fall into the protection scope of the present invention.

Claims

The preparation method of the long-short side chain blended anion exchange membrane is characterized by comprising the steps of acylation of PPO, bromination of PPO, reduction of carbonyl, quaternization of gradient side chain polymer, membrane formation and alkalization, and comprises the following specific steps:

(1) preparation of acylated polyphenylene ethers

Firstly, adding polyphenyl ether into dichloromethane serving as a solvent at room temperature, wherein 0.5-1.5g of polyphenyl ether is correspondingly added into every 10ml of dichloromethane, and stirring until the solution is clear to obtain a polyphenyl ether solution; then, under the protection of nitrogen, adding anhydrous aluminum trichloride into a solvent dichloromethane, and dropwise adding 6-bromohexanoyl chloride under the condition of ice-water bath, wherein 0.5-0.7 g of anhydrous aluminum trichloride is correspondingly added into every 10ml of dichloromethane, and the molar ratio of the anhydrous aluminum trichloride to the 6-bromohexanoyl chloride is 1: 1; stirring for 10min, adding the dissolved polyphenyl ether solution, and reacting at room temperature for 1.5-3 h to obtain a tan solution; finally, pouring the solution into lower alcohol to separate out solid polymer, washing with ethanol, and drying in vacuum to obtain acylated polyphenyl ether;

(2) reduction of side chain carbonyl groups of polyphenylene ethers

Firstly, adding the acylated polyphenyl ether prepared in the step (1) into a reaction vessel, adding dewatered 1, 2-dichloroethane as a solvent under the protection of nitrogen, stirring until the solution is clear, adding excessive trifluoroacetic acid and excessive triethylsilane, and reacting for 36-54h at 80 ℃ under magnetic stirring; secondly, adjusting the pH value of the reaction solution to 8 by adopting NaOH; finally, removing 1, 2-dichloroethane by rotary evaporation, separating out the solid polymer in water, performing suction filtration to obtain the solid polymer, washing and soaking the solid polymer for multiple times by using lower alcohol, and performing vacuum drying to obtain the polyphenyl ether material subjected to carbonyl reduction; the molar ratio of carbonyl of the acylated polyphenylene ether to trifluoroacetic acid and triethylsilane is 1: 100-300: 5-15;

(3) bromination of polyphenylene ethers

Firstly, adding polyphenyl ether into chlorobenzene serving as a solvent, wherein 0.5-1.5g of polyphenyl ether material is correspondingly added into 10mL of chlorobenzene; secondly, heating to 80 ℃, adding azobisisobutyronitrile AIBN and N-bromosuccinimide NBS, and heating to 125 ℃ for reaction for 2-4 h; finally, pouring the solution after reaction into lower alcohol to separate out solid polymer, washing with methanol, and drying in vacuum to obtain brominated polyphenylene oxide; the molar ratio of the PPO to the N-bromosuccinimide NBS to the azobisisobutyronitrile AIBN is 1: 0.6-1: 0.3-0.5;

(4) quaternary amination of polymers

At room temperature, dissolving 0.5g of the polyphenyl ether material prepared in the step (2) and 0.5g of the brominated polyphenyl ether prepared in the step (3) in an organic solvent according to the mass ratio of 9:1, adding 0.4-0.6ml of nitrogen-containing heterocyclic groups, reacting for 12-48h at 30-80 ℃, and carrying out quaternization on the blended polymer to obtain a polymer solution; the nitrogen heterocyclic group is N-methylmorpholine, N-methylpiperidine and N-methylpyrrole; the mol ratio of the bromomethyl to the nitrogen-containing heterocyclic group is 1: 4-6;

(5) cast film

Placing the polymer solution prepared in the step (4) on a glass plate to form a film, and heating for 24-48h at 40-80 ℃;

(6) anion exchange membranes by base exchange

And peeling the obtained membrane from the surface of the glass plate, soaking in 0.1-2M alkali solution for 24-48 hours, and washing off free hydroxide ions in the membrane to obtain the blending type anion exchange membrane.
2. The preparation method of long-short side chain blended anion-exchange membranes according to claim 1, wherein the vacuum drying temperature in step (1) is 30-100 ℃ and the drying time is 12-48h, the vacuum drying temperature in step (2) is 30-100 ℃ and the drying time is 12-48h, the multistage alcohol soaking is 12h, and the vacuum drying temperature in step (3) is 30-100 ℃ and the drying time is 12-48 h.
3. The method for preparing the long-short side chain blended anion-exchange membrane according to claim 1 or 2, wherein the lower alcohol in the step (1) is a mixed solvent of or more of methanol, ethanol and isopropanol, the vacuum drying temperature is 30-100 ℃, the drying time is 12-48h, the lower alcohol in the step (2) is a mixed solvent of or more of methanol, ethanol and isopropanol, and the lower alcohol in the step (3) is a mixed solvent of or more of methanol, ethanol and isopropanol.
4. The method for preparing long-short side chain blend type anion-exchange membranes according to claim 1 or 2, wherein the organic solvent in step (4) is N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, or dimethyl sulfoxide.
5. The method for preparing kinds of long and short side chain blend type anion-exchange membranes according to claim 3, wherein the organic solvent in step (4) is N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, or dimethyl sulfoxide.