Sulfonating method of polyether-ether-ketone, sulfonated polyether-ether-ketone and application of sulfonated polyether-ether-ketone

Abstract

The invention discloses a sulfonation method of polyether-ether-ketone, sulfonated polyether-ether-ketone and application of sulfonated polyether-ether-ketone. The sulfonation method of polyether-ether-ketone comprises the following steps: (1) dissolving polyether-ether-ketone with concentrated sulfuric acid, adding sulfonated graphene and FeCl3, and uniformly stirring to obtain sulfonated feed liquid; (2) separating out the sulfonated material liquid in a pure ice-water mixture of which the temperature is lower than 5 DEG C to obtain a sulfonated polyether-ether-ketone primary material; and (3) separating the primary sulfonated polyetheretherketone material from the ice-water mixture, cleaning and drying to obtain the sulfonated polyetheretherketone. The sulfonated polyetheretherketone / sulfonated graphene composite material obtained by the method has good machinability, moderate viscosity and better solution film-forming property, and the proton exchange membrane obtained by a solution film-forming method is smooth in appearance, free of pores and bulges, excellent in ion exchange capacity, mechanical strength, thermal stability and durability and suitable for industrial production. The method can be used for preparing proton exchange membranes of hydrogen fuel cells.

Description

Technical Field

[0001] This invention relates to the field of proton exchange membrane technology, specifically to a sulfonation method for polyether ether ketone, sulfonated 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 PEMs 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 PEM material, achieving high proton conductivity in a hydrated state. However, it also has some problems. For example, the sulfonic acid groups in SPEEK are randomly and unevenly distributed, making it difficult to form continuous and optimized proton conduction channels like those of perfluorosulfonic acid resins. The microphase separation structure formed by SPEEK is not continuous enough, leading to a decrease in conductivity under low humidity or high temperature conditions. Furthermore, while increasing the degree of sulfonation can alleviate the problem of uneven sulfonic acid group distribution to some extent and improve proton conduction, it can also cause excessive local water absorption by the membrane, resulting in excessive swelling, decreased mechanical properties, and dimensional instability. Therefore, controlling the degree of sulfonation and uniformity of sulfonated polyether ether ketone is a major problem 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 sulfonation method for polyether ether ketone. This method improves the sulfonation uniformity and degree of sulfonation of polyether ether ketone by the presence of sulfonated graphene and FeCl3 during the sulfonation of polyether ether ketone with concentrated sulfuric acid. Furthermore, the proton exchange membrane prepared from the sulfonated polyether ether ketone / sulfonated graphene composite material has excellent ion exchange capacity, mechanical strength and thermal stability.

[0004] To achieve the above objectives, the present invention provides a sulfonation method for polyether ether ketone, comprising the following steps: (1) dissolving polyether ether ketone in concentrated sulfuric acid, adding sulfonated graphene and FeCl3, stirring evenly to obtain a sulfonation solution; (2) precipitating the sulfonation solution in a pure ice-water mixture at a temperature below 5°C to obtain a primary sulfonated polyether ether ketone material; (3) separating the primary sulfonated polyether ether ketone material from the ice-water mixture, washing and drying it to obtain sulfonated polyether ether ketone.

[0005] Optionally, the ratio of concentrated sulfuric acid, polyether ether ketone powder, sulfonated graphene and FeCl3 is 400ml:40g:(3-5)g:(0.5-0.8)g.

[0006] Optionally, the concentration of the concentrated sulfuric acid is not less than 96 wt%.

[0007] Optionally, the sulfonated graphene is obtained by sulfonating graphene with a mixture of concentrated sulfuric acid and fuming sulfuric acid.

[0008] Optionally, the maximum particle size of the polyetheretherketone powder is less than 100 μm, and the particle size of the sulfonated graphene is 1.2-4.0 μm.

[0009] Optionally, the polyetheretherketone powder, sulfonated graphene, and FeCl3 are all pre-dried in a vacuum drying oven at 105-110°C for 8-12 hours.

[0010] Optionally, the cleaning and drying steps are as follows: repeatedly soak and clean with 3% dilute hydrochloric acid 3-5 times, clean with deionized water until the pH value reaches 7, drain and put into a forced-air drying oven, set the temperature to 60℃ and dry for 12 hours.

[0011] Optionally, the temperature at which the concentrated H2SO4 dissolves the polyether ether ketone is 40-60°C.

[0012] The present invention also provides a sulfonated polyether ether ketone prepared 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 beneficial effects of this invention are as follows: 1. This invention adds sulfonated graphene and FeCl3 during the sulfonation of polyether ether ketone with concentrated sulfuric acid, and by controlling the amount of sulfonated graphene and FeCl3, sulfonated polyether ether ketone with good sulfonation uniformity and degree of sulfonation can be obtained. At the same time, sulfonated graphene is uniformly dispersed in sulfonated polyether ether ketone, and the sulfonic acid groups of both are rearranged and distributed more uniformly during the sulfonation process with concentrated sulfuric acid.

[0015] 2. The sulfonated polyether ether ketone / sulfonated graphene composite material obtained by the above method has good processability, moderate viscosity, and better solution film-forming properties. The proton exchange membrane obtained by solution film-forming method has a smooth surface, no pores or protrusions, and has excellent ion exchange capacity, mechanical strength, thermal stability, and durability. Detailed Implementation

[0016] 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.

[0017] 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.

[0018] The sulfonation method of polyether ether ketone according to the present invention comprises the following steps: (1) putting concentrated sulfuric acid with a concentration of not less than 96wt% into a three-necked flask, controlling the temperature of the water bath at 40-60℃, turning on the stirring rod to a speed of 300rpm / min, slowly adding polyether ether ketone powder until the polyether ether ketone is completely dissolved, adding sulfonated graphene and FeCl3, stirring evenly and maintaining for 2-4h to obtain sulfonated solution; the ratio of concentrated sulfuric acid, polyether ether ketone powder, sulfonated graphene and FeCl3 is 400ml:40g:(3-5)g:(0.5-0.8)g. (2) Place a pure ice-water mixture in a beaker to make the water temperature below 5°C. Stir the ice-water mixture continuously with a glass rod to form a vortex and slowly pour it into the sulfonated material solution in a linear fashion, so that the sulfonated polyether ether ketone primary material precipitates out in the ice-water mixture; (3) Separate the sulfonated polyether ether ketone primary material from the ice-water mixture, and repeatedly soak and wash it with 3% dilute hydrochloric acid 3-5 times. After washing 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 12 hours to obtain sulfonated polyether ether ketone. The sulfonated graphene is obtained by sulfonating graphene with a mixture of concentrated sulfuric acid and fuming sulfuric acid. The maximum particle size of the polyether ether ketone powder is less than 100 μm, and the particle size of the sulfonated graphene is 1.2-4.0 μm. The polyether ether ketone powder, sulfonated graphene and FeCl3 are all dried in a vacuum drying oven at 105-110°C for 8-12 hours.

[0019] The sulfonated polyether ether ketone prepared by the above method according to the present invention can be used to prepare proton exchange membranes for hydrogen fuel cells.

[0020] The following examples illustrate the sulfonation method of polyether ether ketone (PEEK) of the present invention, the sulfonated PEEK, and its applications. 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-available materials of the same type and are not subject to specific limitations.

[0021] Example 1 (1) Polyether ether ketone powder, sulfonated graphene and FeCl3 were all dried in a vacuum drying oven at 105℃ for 8-12h; 400ml of 98wt% concentrated H2SO4 was placed in a 1000ml three-necked flask, the water bath temperature was controlled at 40℃, the PTFE stirring rod was turned on to a speed of 300rpm / min, 40g of polyether ether ketone powder was slowly added until the polyether ether ketone was completely dissolved, 3g of sulfonated graphene and 0.5g of FeCl3 were added, and the mixture was stirred evenly and kept for 2h to obtain the sulfonated solution; (2) Place a pure ice-water mixture in a beaker to make the water temperature lower than 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 sulfonated polyether ether ketone primary material is precipitated in the ice-water mixture. (3) Separate the sulfonated polyether ether ketone primary material from the ice-water mixture, and repeatedly soak and wash it three times with dilute hydrochloric acid with a mass concentration of 3%, and wash it with deionized water until the pH value reaches 7. After draining, put it into a forced-air drying oven, set the temperature to 60°C, and dry it for 12 hours to obtain sulfonated polyether ether ketone.

[0022] Example 2 (1) Polyether ether ketone powder, sulfonated graphene and FeCl3 were all dried in a vacuum drying oven at 110℃ for 8-12h. 400ml of 98wt% concentrated H2SO4 was placed in a 1000ml three-necked flask, the water bath temperature was controlled at 60℃, the PTFE stirring rod was turned on to a speed of 300rpm / min, 40g of polyether ether ketone powder was slowly added until the polyether ether ketone was completely dissolved, 5g of sulfonated graphene and 0.8g of FeCl3 were added, and the mixture was stirred evenly and kept for 4h to obtain the sulfonated solution. (2) Place a pure ice-water mixture in a beaker to make the water temperature lower than 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 sulfonated polyether ether ketone primary material is precipitated in the ice-water mixture. (3) Separate the sulfonated polyether ether ketone primary material from the ice-water mixture, and repeatedly soak and wash it 5 times with dilute hydrochloric acid with a mass concentration of 3%, and wash it with deionized water until the pH value reaches 7. After draining, put it into a forced-air drying oven, set the temperature to 60°C, and dry it for 12 hours to obtain sulfonated polyether ether ketone.

[0023] Example 3 (1) Polyether ether ketone powder, sulfonated graphene and FeCl3 were all dried in a vacuum drying oven at 108℃ for 10h. 400ml of 98wt% concentrated H2SO4 was placed in a 1000ml three-necked flask, the water bath temperature was controlled at 50℃, the PTFE stirring rod was turned on to a speed of 300rpm / min, 40g of polyether ether ketone powder was slowly added until the polyether ether ketone was completely dissolved, 4g of sulfonated graphene and 0.65g of FeCl3 were added, and the mixture was stirred evenly and kept for 3h to obtain the sulfonated solution. (2) Place a pure ice-water mixture in a beaker to make the water temperature lower than 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 sulfonated polyether ether ketone primary material is precipitated in the ice-water mixture. (3) Separate the sulfonated polyether ether ketone primary material from the ice-water mixture, and repeatedly soak and wash it 4 times with dilute hydrochloric acid with a mass concentration of 3%, and wash it with deionized water until the pH value reaches 7. After draining, put it into a forced-air drying oven, set the temperature to 60°C, and dry it for 12 hours to obtain sulfonated polyether ether ketone.

[0024] Comparative Example 1 Except for the absence of sulfonated graphene, it is the same as in Example 3.

[0025] Comparative Example 2 Except for the absence of FeCl3, everything else was the same as in Example 3.

[0026] Performance testing 1. The degree of sulfonation of sulfonated polyether ether ketone 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.

[0027] Table 1 2. Prepare a solution of sulfonated polyether ether ketone and DMF at a ratio of 15g:150ml. Apply the solution evenly to the surface of a glass plate. Control the film thickness to 60μm with a doctor blade. Dry the film in an oven by sequentially increasing the temperature to 50℃ / 6h and 80℃ / 5h to obtain a sulfonated polyether ether ketone film. Perform the following tests. See Table 2 for specific data.

[0028] Table 2 As can be seen from the examples and comparative data, the present invention, by adding sulfonated graphene and FeCl3 during the sulfonation of polyether ether ketone with concentrated sulfuric acid and by controlling the amount of sulfonated graphene and FeCl3, can obtain sulfonated polyether ether ketone with good sulfonation uniformity and degree of sulfonation. The prepared sulfonated polyether ether ketone has good processability, moderate viscosity, better solution film-forming properties, a smooth and flat surface without pores or protrusions, excellent ion exchange capacity, mechanical strength and thermal stability, and better service durability.

[0029] 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 sulfonating polyetheretherketone, characterized in that, It includes the following steps: (1) Dissolve polyether ether ketone in concentrated sulfuric acid, add sulfonated graphene and FeCl3, stir evenly to obtain sulfonated solution; (2) The sulfonated liquid is precipitated in a pure ice-water mixture at a temperature below 5°C to obtain sulfonated polyether ether ketone primary material; (3) The sulfonated polyether ether ketone primary material is separated from the ice-water mixture, washed and dried to obtain sulfonated polyether ether ketone.

2. The sulfonation method for polyetheretherketone as described in claim 1, characterized in that, The ratio of concentrated sulfuric acid, polyether ether ketone powder, sulfonated graphene, and FeCl3 is 400ml:40g:(3-5)g:(0.5-0.8)g.

3. The sulfonation method for polyetheretherketone as described in claim 1 or 2, characterized in that, The concentration of the concentrated sulfuric acid is not less than 96 wt%.

4. The sulfonation method for polyetheretherketone as described in claim 1 or 2, characterized in that, The sulfonated graphene is obtained by sulfonating graphene with a mixture of concentrated sulfuric acid and fuming sulfuric acid.

5. The sulfonation method for polyetheretherketone as described in claim 1 or 2, characterized in that, The maximum particle size of the polyetheretherketone powder is less than 100 μm, and the particle size of the sulfonated graphene is 1.2-4.0 μm.

6. The sulfonation method for polyetheretherketone as described in claim 1 or 2, characterized in that, The polyetheretherketone powder, sulfonated graphene, and FeCl3 were all pre-dried in a vacuum drying oven at 105-110℃ for 8-12 hours.

7. The sulfonation method for polyetheretherketone as described in claim 1 or 2, characterized in that, The cleaning and drying steps are as follows: repeatedly soak and clean with 3% dilute hydrochloric acid 3-5 times, clean with deionized water until the pH value reaches 7, drain and put into a forced-air drying oven, set the temperature to 60℃ and dry for 12 hours.

8. The sulfonation method for polyetheretherketone as described in claim 1 or 2, characterized in that, The temperature at which concentrated H2SO4 dissolves polyether ether ketone is 40-60℃.

9. A sulfonated polyether ether ketone prepared by the sulfonation method according to any one of claims 1-8.

10. An application of the sulfonated polyether ether ketone as described in claim 9, characterized in that, Proton exchange membranes used in the preparation of hydrogen fuel cells.

Images