Preparation method of sulfonated polyether-ether-ketone, high-sulfonation-degree polyether-ether-ketone and application of high-sulfonation-degree polyether-ether-ketone

Abstract

The invention discloses a preparation method of sulfonated polyether-ether-ketone, high-sulfonation-degree polyether-ether-ketone and application of the high-sulfonation-degree polyether-ether-ketone, and belongs to the technical field of proton exchange membranes. The preparation method of the sulfonated polyether-ether-ketone comprises the following steps: (1) adding a solvent, a sodium sulfonate group-containing difluorobenzophenone monomer, a difluorobenzophenone monomer, a bisphenol monomer, sulfonated graphene and a catalyst into a reaction kettle, uniformly stirring under the protection of nitrogen, heating to the reaction temperature of 160-180 DEG C, keeping the reaction for 2-4 hours, cooling, filtering, washing, and drying to obtain sulfonated polyether-ether-ketone; pouring into water and separating out to obtain a sulfonated polyether ether ketone primary material; and (2) crushing the primary sulfonated polyetheretherketone material, sequentially pickling with hydrochloric acid, cleaning with ethanol, washing with deionized water, and carrying out vacuum drying for 24 hours to obtain the sulfonated polyetheretherketone. The sulfonated polyetheretherketone prepared by the preparation method can be used for preparing a proton exchange membrane of a hydrogen fuel cell.

Description

Technical Field

[0001] This invention relates to the field of proton exchange membrane technology, specifically to a method for preparing sulfonated polyether ether ketone, high-sulfonation polyether ether ketone, and its applications. Background Technology

[0002] With the development of clean energy technologies such as fuel cells, hydrogen energy, and water electrolysis for hydrogen production, the proton exchange membrane (PEM), as a core component of fuel cells, directly determines the overall efficiency and lifespan of the fuel cell. Currently, the most widely used proton exchange membranes on the market are mainly represented by perfluorosulfonic acid resins (such as Nafion). However, the high cost of perfluorosulfonic acid resins has always been one of the main factors hindering the commercialization of fuel cells. In recent years, sulfonated polyether ether ketone (SPEEK) has emerged as a low-cost proton exchange membrane material, achieving high proton conductivity in the hydrated state. However, it also presents several challenges. For instance, the direct sulfonation method, which uses concentrated sulfuric acid to treat polyether ether ketone, results in a random and uneven distribution of sulfonic acid groups, making it difficult to form continuous and optimized proton conduction channels similar to perfluorosulfonic acid resins. The microphase separation structure formed by SPEEK is also not continuous enough, leading to decreased conductivity under low humidity or high temperature conditions. Furthermore, while monomer polymerization can synthesize sulfonated polyether ketone to some extent, it suffers from a narrow sulfonation degree adjustment range, making it difficult to increase the degree of sulfonation. This can cause excessive local water absorption in the membrane, excessive swelling leading to decreased mechanical properties and dimensional instability. Therefore, controlling the degree of sulfonation and uniformity of sulfonated polyether ketone is a major challenge in this field. Summary of the Invention

[0003] In view of the problems existing in the background art, the purpose of the present invention is to provide a method for preparing sulfonated polyether ether ketone. This method introduces sulfonated graphene into the synthesis process of sulfonated polyether ether ketone, and finds that its high specific surface area with sulfonic acid groups is beneficial to the polymerization reaction and can reduce the reaction temperature. The obtained sulfonated polyether ether ketone can be sulfonated to a high degree of sulfonation polyether ether ketone. The high degree of sulfonation polyether ether ketone has good processability, moderate viscosity, and better solution film-forming properties. The proton exchange membrane obtained by the solution film-forming method has a smooth appearance, no pores or protrusions, and has excellent ion exchange capacity, mechanical strength, thermal stability, and durability.

[0004] To achieve the above objectives, the present invention also provides a method for preparing sulfonated polyether ether ketone, comprising the following steps: (1) adding solvent, sodium sulfonate-based difluorobenzophenone monomer, difluorobenzophenone monomer, bisphenol monomer, sulfonated graphene and catalyst to a reaction vessel, stirring evenly under nitrogen protection and heating to a reaction temperature of 160-180℃, maintaining the reaction for 2-4 hours, cooling down, and pouring into water to precipitate and obtain sulfonated polyether ether ketone primary material; (2) crushing the sulfonated polyether ether ketone primary material, washing it sequentially with hydrochloric acid, ethanol, and deionized water, and drying it under vacuum for 24 hours to obtain sulfonated polyether ether ketone.

[0005] Optionally, the mass ratio of the sodium sulfonate-containing difluorobenzophenone monomer, difluorobenzophenone monomer, bisphenol monomer, sulfonated graphene, catalyst and solvent is (30-50):80:100:(10-15):(50-60):(300-500).

[0006] Optionally, the sodium sulfonate-containing difluorobenzophenone monomer is 3,3'-sodium disulfonate-4,4'-difluorobenzophenone.

[0007] Optionally, the catalyst is one or a combination of potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, and tetrabutylammonium bromide.

[0008] Optionally, the difluorobenzophenone monomer is one or a combination of 4,4'-difluorobenzophenone and 4,4'-difluorotribenzophenone.

[0009] Optionally, the bisphenol monomer is one or a combination of hydroquinone, 4,4'-dihydroxybenzophenone, and tert-butylhydroquinone.

[0010] Optionally, the sulfonated graphene has a particle size of 1.2-4.0 μm, a thickness of 0.8-6.6 nm, a number of layers of <5, and an S content of 2.2-6.4 wt%.

[0011] Optionally, the solvent is one or a combination of toluene, dimethylacetamide, and diphenyl sulfone.

[0012] The present invention also provides a sulfonated polyether ether ketone obtained by the above method.

[0013] The present invention also provides an application of the above-mentioned sulfonated polyether ether ketone for the preparation of a proton exchange membrane for a hydrogen fuel cell.

[0014] The present invention also provides a high degree of sulfonation polyether ether ketone, which is obtained by sulfonation of the sulfonated polyether ether ketone prepared by the above-described method.

[0015] The present invention also provides an application of the above-mentioned high-sulfonation polyether ether ketone for the preparation of proton exchange membranes for hydrogen fuel cells.

[0016] The beneficial effects of this invention are as follows: By introducing sulfonated graphene into the synthesis of sulfonated polyether ether ketone, it was found that its high specific surface area with sulfonic acid groups is beneficial to the polymerization reaction and can lower the reaction temperature. The resulting sulfonated polyether ether ketone can be sulfonated to a high degree of sulfonation polyether ether ketone. This high degree of sulfonation polyether ether ketone has good processability, moderate viscosity, and better solution film-forming properties. The proton exchange membrane obtained by the solution film-forming method has a smooth appearance, no pores or protrusions, and has excellent ion exchange capacity, mechanical strength, thermal stability, and durability. Detailed Implementation

[0017] To make the above-mentioned objects, features and advantages of the invention more apparent and understandable, the specific embodiments of the invention are described in detail below.

[0018] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0019] The preparation method of sulfonated polyether ether ketone according to the present invention comprises the following steps: (1) adding solvent, sodium sulfonate-based difluorobenzophenone monomer, difluorobenzophenone monomer, bisphenol monomer, sulfonated graphene and catalyst to a reaction vessel, stirring evenly under nitrogen protection and heating to a reaction temperature of 160-180℃, maintaining the reaction for 2-4 hours, cooling down, and pouring into water to precipitate and obtain sulfonated polyether ether ketone primary material; (2) pulverizing the sulfonated polyether ether ketone primary material, washing it sequentially with hydrochloric acid, washing it with ethanol, washing it with deionized water, and vacuum drying it for 24 hours to obtain sulfonated polyether ether ketone. The mass ratio of sodium sulfonate-based difluorobenzophenone monomer, difluorobenzophenone monomer, bisphenol monomer, sulfonated graphene, catalyst and solvent can be (30-50):80:100:(10-15):(50-60):(300-500). The sodium sulfonate-containing difluorobenzophenone monomer may be 3,3'-disulfonate sodium-4,4'-difluorobenzophenone. The catalyst may be one or a combination of potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, and tetrabutylammonium bromide. The difluorobenzophenone monomer may be one or a combination of 4,4'-difluorobenzophenone and 4,4'-difluorotribenzophenone. The bisphenol monomer may be one or a combination of hydroquinone, 4,4'-dihydroxybenzophenone, and tert-butylhydroquinone. The sulfonated graphene may have a particle size of 1.2-4.0 μm, a thickness of 0.8-6.6 nm, a number of layers <5, and an S content of 2.2-6.4 wt%. The solvent may be one or a combination of toluene, dimethylacetamide, and diphenyl sulfone.

[0020] The sulfonated polyether ether ketone prepared by the method described above according to the present invention can be used to prepare proton exchange membranes for hydrogen fuel cells.

[0021] The high-sulfonation polyether ether ketone according to the present invention is obtained by sulfonation of the sulfonated polyether ether ketone prepared by the above-described method. The high-sulfonation polyether ether ketone can be used to prepare proton exchange membranes for hydrogen fuel cells.

[0022] The following examples illustrate the preparation method of sulfonated polyether ether ketone, high-sulfonation polyether ether ketone, and its applications according to the present invention. Main raw materials and equipment used: Unless otherwise specified, the raw materials and equipment used in each example and comparative example are the same; materials not specifically designated as such are derived from common, market-purchased materials of the same type and are not specifically limited.

[0023] Example 1 1. According to the mass fraction, add 300 parts toluene, 30 parts 3,3'-disulfonate sodium-4,4'-difluorobenzophenone, 80 parts 4,4'-difluorotribenzophenone, 100 parts tert-butylhydroquinone, 10 parts sulfonated graphene and 50 parts potassium carbonate to the reaction vessel, stir evenly under nitrogen protection and heat to the reaction temperature of 160°C, maintain the reaction for 2 hours, cool down, pour into water to precipitate and obtain sulfonated polyether ether ketone primary material; (2) After crushing the sulfonated polyether ether ketone primary material, wash it with hydrochloric acid 3 times, wash it with ethanol 3 times, wash it with deionized water until the water is neutral, and vacuum dry it for 24 hours to obtain sulfonated polyether ether ketone.

[0024] 2. Resulfonation of sulfonated polyether ether ketone: (1) After drying the sulfonated polyether ether ketone, grind it into powder, dissolve it in concentrated sulfuric acid with a concentration of 97wt%, heat it to 60°C, add catalyst FeCl3, raise the temperature to 80°C, and continue the reaction for 10h to obtain sulfonated liquid; (2) Put pure ice-water mixture into a beaker, so that the water temperature is below 5°C, stir the ice-water mixture continuously with a glass rod to form a vortex and slowly pour it into the sulfonated liquid in a line, so that the liquid precipitates the primary sulfonated polyether ether ketone in the ice-water mixture; (3) Separate the primary sulfonated polyether ether ketone from the ice-water mixture, soak and wash it repeatedly with dilute hydrochloric acid with a concentration of 3wt% 5 times, wash it with deionized water until the pH value reaches 7, drain it and put it into a forced-air drying oven, set the temperature to 60°C, and dry it for 12h to obtain high sulfonated polyether ether ketone.

[0025] Example 2 1. According to the mass fraction, add 500 parts of dimethylacetamide, 50 parts of sodium 3,3'-disulfonate-4,4'-difluorobenzophenone, 80 parts of 4,4'-difluorobenzophenone, 100 parts of 4,4'-dihydroxybenzophenone, 15 parts of sulfonated graphene and 60 parts of sodium carbonate to the reaction vessel, stir evenly under nitrogen protection and heat to the reaction temperature of 180°C, maintain the reaction for 4 hours, cool down, pour into water to precipitate and obtain sulfonated polyether ether ketone primary material; (2) After crushing the sulfonated polyether ether ketone primary material, wash it with hydrochloric acid 5 times, wash it with ethanol 3 times, wash it with deionized water until the water is neutral, and vacuum dry it for 24 hours to obtain sulfonated polyether ether ketone.

[0026] 2. Resulfonation of sulfonated polyether ether ketone: (1) After drying the sulfonated polyether ether ketone, grind it into powder, dissolve it in concentrated sulfuric acid with a concentration of 97wt%, heat it to 60°C, add catalyst FeCl3, raise the temperature to 80°C, and continue the reaction for 10h to obtain sulfonated liquid; (2) Put pure ice-water mixture into a beaker, so that the water temperature is below 5°C, stir the ice-water mixture continuously with a glass rod to form a vortex and slowly pour it into the sulfonated liquid in a line, so that the liquid precipitates the primary sulfonated polyether ether ketone in the ice-water mixture; (3) Separate the primary sulfonated polyether ether ketone from the ice-water mixture, soak and wash it repeatedly with dilute hydrochloric acid with a concentration of 3wt% 5 times, wash it with deionized water until the pH value reaches 7, drain it and put it into a forced-air drying oven, set the temperature to 60°C, and dry it for 12h to obtain high sulfonated polyether ether ketone.

[0027] Example 3 1. According to the mass fraction, add 400 parts of diphenyl sulfone, 40 parts of sodium 3,3'-disulfonate-4,4'-difluorobenzophenone, 80 parts of 4,4'-difluorobenzophenone, 100 parts of hydroquinone, 12 parts of sulfonated graphene and 55 parts of potassium carbonate to the reaction vessel, stir evenly under nitrogen protection and heat to the reaction temperature of 170°C, maintain the reaction for 3 hours, cool down, pour into water to precipitate and obtain sulfonated polyether ether ketone primary material; (2) After crushing the sulfonated polyether ether ketone primary material, wash it with hydrochloric acid 4 times, wash it with ethanol 3 times, wash it with deionized water until the water is neutral, and vacuum dry it for 24 hours to obtain sulfonated polyether ether ketone.

[0028] 2. Resulfonation of sulfonated polyether ether ketone: (1) After drying the sulfonated polyether ether ketone, grind it into powder, dissolve it in concentrated sulfuric acid with a concentration of 97wt%, heat it to 60°C, add catalyst FeCl3, raise the temperature to 80°C, and continue the reaction for 10h to obtain sulfonated liquid; (2) Put pure ice-water mixture into a beaker, so that the water temperature is below 5°C, stir the ice-water mixture continuously with a glass rod to form a vortex and slowly pour it into the sulfonated liquid in a line, so that the liquid precipitates the primary sulfonated polyether ether ketone in the ice-water mixture; (3) Separate the primary sulfonated polyether ether ketone from the ice-water mixture, soak and wash it repeatedly with dilute hydrochloric acid with a concentration of 3wt% 5 times, wash it with deionized water until the pH value reaches 7, drain it and put it into a forced-air drying oven, set the temperature to 60°C, and dry it for 12h to obtain high sulfonated polyether ether ketone.

[0029] Comparative Example 1 Except for the absence of sulfonated graphene and the reaction temperature of 195°C, the process was the same as in Example 3, yielding sulfonated polyether ether ketone.

[0030] Performance testing 1. The degree of sulfonation of the high sulfonated polyether ether ketone of Examples 1-3 and the sulfonated polyether ether ketone of Comparative Example 1 was tested by point titration. Ten samples were taken from different parts of each example. The test results were statistically analyzed, and the average value and deviation were calculated. The specific data are shown in Table 1.

[0031] Table 1 2. A solution was prepared by mixing the high-sulfonation degree polyether ether ketone (PEEEK) of Examples 1-3 and the sulfonated PEEK of Comparative Example 1 with DMF at a ratio of 15g:150ml. The solution was uniformly coated onto the surface of a glass plate, and the film thickness was controlled to 60μm using a doctor blade. The film was then dried in an oven at 50℃ / 6h and 80℃ / 5h in stages to obtain a sulfonated PEEK film. Simultaneously, Comparative Example 2 was provided: a solution was prepared by mixing the sulfonated PEEK of Comparative Example 1, sulfonated graphene, and DMF at a ratio of 15g:0.81g:150ml. The solution was uniformly coated onto the surface of a glass plate, and the film thickness was controlled to 60μm using a doctor blade. The film was then dried in an oven at 50℃ / 6h and 80℃ / 5h in stages to obtain a sulfonated PEEK film. The obtained films were tested as follows, and the specific data are shown in Table 2.

[0032] Table 2 As can be seen from the examples and comparative data, the present invention can reduce the reaction temperature by adding sulfonated graphene during the synthesis of sulfonated polyether ether ketone; the sodium sulfonate-containing difluorobenzophenone monomer is more uniformly distributed in the polymer, and high-sulfonation polyether ether ketone can be prepared by conventional sulfonation. It has good processability, moderate viscosity, better solution film-forming properties, smooth and flat appearance without pores and protrusions, excellent ion exchange capacity, mechanical strength and thermal stability, and better service durability.

[0033] The above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing sulfonated polyether ether ketone, characterized in that, The process includes the following steps: (1) Add solvent, sodium sulfonate-based difluorobenzophenone monomer, difluorobenzophenone monomer, bisphenol monomer, sulfonated graphene and catalyst to a reaction vessel, stir evenly under nitrogen protection and heat to the reaction temperature of 160-180℃, maintain the reaction for 2-4 hours, cool down, pour into water to precipitate and obtain sulfonated polyether ether ketone primary material; (2) After crushing the sulfonated polyether ether ketone primary material, wash it with hydrochloric acid, clean it with ethanol, wash it with deionized water, and vacuum dry it for 24 hours to obtain sulfonated polyether ether ketone.

2. The method for preparing sulfonated polyether ether ketone according to claim 1, characterized in that, The mass ratio of the sodium sulfonate-containing difluorobenzophenone monomer, difluorobenzophenone monomer, bisphenol monomer, sulfonated graphene, catalyst and solvent is (30-50):80:100:(10-15):(50-60):(300-500).

3. The method for preparing sulfonated polyether ether ketone according to claim 1, characterized in that, The sodium sulfonate-containing difluorobenzophenone monomer is 3,3'-sodium disulfonate-4,4'-difluorobenzophenone.

4. The method for preparing sulfonated polyether ether ketone according to claim 1, characterized in that, The catalyst is one or a combination of potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, and tetrabutylammonium bromide.

5. The method for preparing sulfonated polyether ether ketone according to claim 1, characterized in that, The difluorobenzophenone monomer is one or a combination of 4,4'-difluorobenzophenone and 4,4'-difluorotribenzophenone.

6. The method for preparing sulfonated polyether ether ketone according to claim 1, characterized in that, The bisphenol monomer is one or a combination of hydroquinone, 4,4'-dihydroxybenzophenone and tert-butylhydroquinone.

7. The method for preparing sulfonated polyether ether ketone according to claim 1, characterized in that, The sulfonated graphene has a particle size of 1.2-4.0 μm, a thickness of 0.8-6.6 nm, a number of layers of <5, and an S content of 2.2-6.4 wt%.

8. The method for preparing sulfonated polyether ether ketone according to claim 1, characterized in that, The solvent is one or a combination of toluene, dimethylacetamide, and diphenyl sulfone.

9. A high-sulfonation polyetheretherketone, characterized in that, The sulfonated polyether ether ketone prepared by the method described in any one of claims 1-8 is obtained by sulfonation.

10. An application of the high sulfonation degree polyetheretherketone according to claim 9, characterized in that, Proton exchange membranes used in the preparation of hydrogen fuel cells.

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