Method for preparing sulfonated polyetheretherketone

Abstract

The invention provides a method for preparing sulfonated polyetheretherketone, and belongs to the technical field of polycondensates of ketone and phenol. The preparation method comprises the following steps: preparing modified polyether-ether-ketone, pretreating, sulfonating and post-treating. The method for preparing the modified polyether-ether-ketone comprises the following steps: under the protection of nitrogen, adding 4, 4 '-difluorobenzophenone, hydroquinone and diphenyl sulfone into a reaction kettle, heating to 170-190 DEG C, adding a catalyst, keeping the temperature for 0.8-1.2 hours, dropwise adding a PEG-400 solution at 260-290 DEG C, controlling the dropwise adding time to be 1.5-2.5 hours, reacting at 310-330 DEG C for 1.5-3.5 hours after dropwise adding is finished, cooling and crystallizing after the reaction is finished, and washing off a solvent and inorganic salt to obtain the modified polyether-ether-ketone. Modified polyether-ether-ketone is obtained; according to the sulfonated polyether-ether-ketone disclosed by the invention, the sulfonation degree is 69.6 to 75.1 percent, the sulfonation uniformity is good, and the deviation is 2.37 to 2.52 percent.

Description

Technical Field

[0001] The present invention belongs to the technical field of polycondensates of ketones and phenols, and particularly relates to a method for preparing sulfonated polyether ether ketone. Background Art

[0002] New energy power represented by photovoltaic and wind power has developed rapidly. However, clean energies such as solar energy and wind energy are restricted by time, season and space, and their power generation processes are intermittent and volatile. Large-scale grid connection will cause a huge impact on the safety and stability of the power system. Large-scale energy storage technology is an effective way to solve the instability and intermittency of wind and solar power generation. Compared with other energy storage technologies, flow batteries have become one of the current mainstream energy storage technologies due to their advantages such as high energy efficiency, large energy storage scale, high safety performance, and long cycle life.

[0003] Among the key materials that make up flow batteries, ion exchange membranes have always been the focus of research. It separates the positive and negative electrode solutions, maintains the transfer of conductive ions, realizes the selective passage and separation of ions, and provides basic support for the efficient operation of flow batteries. Sulfonated polyether ether ketone membranes have advantages such as good ion selectivity, low cost, simple preparation process, and avoidance of cross-contamination. Therefore, their research and application are becoming more and more extensive. Among them, improving the sulfonation uniformity of polyether ether ketone is crucial for enhancing the performance of sulfonated polyether ether ketone membranes.

[0004] Currently, the most commonly used preparation method is solution sulfonation. Its main principle is to carry out an electrophilic substitution reaction on polyether ether ketone in a solvent using a strong sulfonating agent (such as concentrated sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, etc.), introduce a sulfonic acid group (-SO3H) into the benzene ring structure, and obtain sulfonated polyether ether ketone.

[0005] However, the following problems will affect the sulfonation uniformity of polyether ether ketone: 1. The entanglement of molecular chains in polyether ether ketone particles or solutions hinders the diffusion of sulfonating agents, resulting in a higher degree of sulfonation on the surface than inside, or over-sulfonation in local areas; 2. The reaction between polyether ether ketone and high-concentration sulfonating agents such as concentrated sulfuric acid is violent, and local overheating leads to degradation or uneven sulfonation degree; 3. Due to the crystallinity of the polyether ether ketone molecular chain, the molecular arrangement in the crystalline region is tight, and it is difficult for sulfonating agents to penetrate, resulting in a higher sulfonation degree in the amorphous region than in the crystalline region. Summary of the Invention

[0006] Aiming at the problems existing in the prior art, the present invention provides a method for preparing sulfonated polyether ether ketone, achieving the following invention purposes: providing a sulfonated polyether ether ketone with uniform sulfonation degree, high ion exchange capacity, good tensile strength, and high thermal decomposition temperature for the prepared sulfonated polyether ether ketone membrane.

[0007] To solve the above technical problems, the technical solutions adopted by the present invention are as follows: A method for preparing sulfonated polyether ether ketone, comprising: 1. Preparation of modified polyetheretherketone Under nitrogen protection, 4,4'-difluorobenzophenone, hydroquinone and diphenyl sulfone are added to a reaction kettle. After heating to 170 - 190 °C, a catalyst is added, and the temperature is kept for 0.8 - 1.2 h. Then, a PEG-400 solution is added dropwise at 260 - 290 °C, and the dropping time is controlled to be 1.5 - 2.5 h. After the dropping is completed, the reaction is carried out at 310 - 330 °C for 1.5 - 3.5 h. After the reaction is completed, it is cooled and crystallized, and successively extracted with acetone and washed with deionized water to remove the solvent and inorganic salts, obtaining the modified polyetheretherketone; The mass ratio of the 4,4'-difluorobenzophenone, hydroquinone, diphenyl sulfone, catalyst and PEG-400 solution is 59 - 63∶21 - 23∶125 - 137∶46 - 50∶22 - 26; The mass fraction of the PEG-400 solution is 20 - 30%; The catalyst is calcium carbonate.

[0008] 2. Pretreatment After drying the modified polyetheretherketone in an oven to remove moisture, it is ball-milled into a powder with a particle size of 8 - 12 μm, and then dissolved and left standing in N-methylpyrrolidone for 20 - 40 min to obtain a modified polyetheretherketone solution; The mass ratio of the modified polyetheretherketone to N-methylpyrrolidone is 0.8 - 1.2∶12 - 14; The drying temperature is 60 - 100 °C, and the drying time is 6 - 8 h.

[0009] 3. Sulfonation Concentrated sulfuric acid and dichloroethane are added to a reaction kettle, and stirring is started. After preheating to 40 - 60 °C, a catalyst FeCl3 is added. Then, the modified polyetheretherketone solution is evenly divided into 6 - 10 portions and added to the reaction kettle in batches, with a time interval of 30 - 50 min between each batch. After the feeding is completed, the temperature is raised to 70 - 80 °C, and the reaction continues for 6 - 10 h, and the reaction is completed; The mass ratio of the concentrated sulfuric acid, dichloroethane, FeCl3 and modified polyetheretherketone solution is 2.5 - 3.5∶0.8 - 1.2∶0.005 - 0.007∶4.1 - 4.3; For the stirring, the initial rate is 100 - 200 r / min, and when the catalyst FeCl3 is added, the stirring rate is increased to 1000 - 1600 r / min.

[0010] 4. Post-treatment The reacted materials are discharged through the discharge port of the reaction kettle and put into a product barrel filled with thermostatic deionized water within 20 - 40 minutes. The temperature of the deionized water is 5 - 25°C, accounting for 30 - 40% of the total volume of the product barrel. After the discharging is completed, the sulfonated polyether ether ketone is washed with deionized water until it is neutral, and then put into an oven for drying to obtain sulfonated polyether ether ketone; The temperature of the oven is 60 - 100°C, and the drying time is 12 - 16 h.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: For the sulfonated polyether ether ketone of the present invention, a hydrophilic spacer group PEG - 400 chain segment is introduced during the synthesis stage of polyether ether ketone, which improves the solubility of the prepolymer in the sulfonating agent concentrated sulfuric acid and makes the distribution of sulfonic acid groups more uniform; The pretreatment process is increased. First, polyether ether ketone is pulverized to the micron level by ball milling to increase the surface area and destroy part of the crystalline structure, promoting the penetration of the sulfonating agent concentrated sulfuric acid. Then, the polyether ether ketone powder is dissolved in N - methylpyrrolidone to make the molecular chains stretch and swell, improving the contact efficiency with the sulfonating agent concentrated sulfuric acid; During the sulfonation process, a mixed system of concentrated sulfuric acid and the inert solvent dichloroethane is used, and polyether ether ketone is added in batches at the same time, reducing the severity of the reaction, slowing down local overheating, and avoiding local degradation at high temperatures; Through the regulation by the above - mentioned various methods, the sulfonation uniformity of the sulfonated polyether ether ketone is improved; For the sulfonated polyether ether ketone of the present invention, the sulfonation degree is 69.6 - 75.1%, the sulfonation uniformity is good, the deviation is 2.37 - 2.52%, the ion - exchange capacity of the sulfonated polyether ether ketone diaphragm prepared is 2.16 - 2.21 mmol / g, the tensile strength is 33.8 - 36.5 MPa, and the thermal decomposition temperature is 285 - 307°C. Specific Embodiments

[0012] Example 1 A method for preparing sulfonated polyether ether ketone, comprising: 1. Preparation of modified polyether ether ketone Under nitrogen protection, 4,4'-difluorobenzophenone, hydroquinone, and diphenyl sulfone are added to a reaction kettle. After heating to 180°C, a catalyst is added, and the temperature is kept for 1 h. Then, a PEG - 400 solution is added dropwise at 275°C, and the dropping time is controlled to be 2 h. After the dropping is completed, the reaction is carried out at 320°C for 2.5 h. After the reaction is completed, it is cooled and crystallized, and successively extracted with acetone and washed with deionized water to remove the solvent and inorganic salts to obtain modified polyether ether ketone; The mass ratio of 4,4'-difluorobenzophenone, hydroquinone, diphenyl sulfone, catalyst, and PEG - 400 solution is 61∶22∶131∶48∶24; The mass fraction of the PEG - 400 solution is 25%; The catalyst is calcium carbonate.

[0013] 2. Pretreatment After drying the modified polyetheretherketone in an oven to remove moisture, it is ball-milled into a powder with a particle size of 10 μm, and then dissolved and left standing for 30 min in N-methylpyrrolidone to obtain a modified polyetheretherketone solution; The mass ratio of the modified polyetheretherketone to N-methylpyrrolidone is 1:13; The drying temperature is 80 °C and the drying time is 7 h.

[0014] 3. Sulfonation Concentrated sulfuric acid and dichloroethane are added to a reaction kettle, stirring is started, after preheating to 50 °C, the catalyst FeCl3 is added, and then the modified polyetheretherketone solution is evenly divided into 8 portions and added to the reaction kettle in batches, with a time interval of 40 min between each batch. After the feeding is completed, the temperature is raised to 75 °C and the reaction continues for 8 h, and the reaction is completed; The mass ratio of the concentrated sulfuric acid, dichloroethane, FeCl3, and modified polyetheretherketone solution is 3:1:0.006:4.2; For the stirring, the initial rate is 150 r / min, and when the catalyst FeCl3 is added, the stirring rate is increased to 1300 r / min.

[0015] 4. Post-treatment The reacted material is discharged from the reaction kettle outlet and put into a product barrel filled with constant-temperature deionized water within 30 min. The temperature of the deionized water is 15 °C, accounting for 35% of the total volume of the product barrel. After the discharging is completed, the sulfonated polyetheretherketone is washed with deionized water until it is neutral, and then put into an oven to be dried to obtain sulfonated polyetheretherketone; The oven temperature is 80 °C and the drying time is 14 h.

[0016] Example 2 A method for preparing sulfonated polyetheretherketone, comprising: 1. Preparation of modified polyetheretherketone Under nitrogen protection, 4,4'-difluorobenzophenone, hydroquinone, and diphenyl sulfone are added to a reaction kettle. After heating to 170 °C, the catalyst is added, and the temperature is maintained for 0.8 h. Then, a PEG-400 solution is added dropwise at 260 °C, and the dropping time is controlled to be 1.5 h. After the dropping is completed, the reaction is carried out at 310 °C for 1.5 h. After the reaction is completed, it is cooled and crystallized, and successively extracted with acetone and washed with deionized water to remove the solvent and inorganic salts to obtain modified polyetheretherketone; The mass ratio of the 4,4'-difluorobenzophenone, hydroquinone, diphenyl sulfone, catalyst, and PEG-400 solution is 59:21:125:46:22; The mass fraction of the PEG-400 solution is 20%; The catalyst is calcium carbonate.

[0017] 2. Pretreatment After drying the modified polyether ether ketone in an oven to remove moisture, it is ball-milled into a powder with a particle size of 8 μm, and then dissolved and allowed to stand for 20 min in N-methylpyrrolidone to obtain a modified polyether ether ketone solution; The mass ratio of the modified polyether ether ketone to N-methylpyrrolidone is 0.8∶12; The drying temperature is 60 °C and the drying time is 6 h.

[0018] 3. Sulfonation Concentrated sulfuric acid and dichloroethane are added to the reaction kettle, stirring is started, and after preheating to 40 °C, the catalyst FeCl3 is added. Then the modified polyether ether ketone solution is evenly divided into 6 portions and added to the reaction kettle batch by batch, with a time interval of 30 min between each batch. After the feeding is completed, the temperature is raised to 70 °C and the reaction continues for 6 h, and the reaction is completed; The mass ratio of the concentrated sulfuric acid, dichloroethane, FeCl3, and modified polyether ether ketone solution is 2.5∶0.8∶0.005∶4.1; For the stirring, the initial rate is 100 r / min, and when the catalyst FeCl3 is added, the stirring rate is increased to 1000 r / min.

[0019] 4. Post-treatment The reacted material is discharged from the reaction kettle outlet and put into a product barrel filled with constant-temperature deionized water within 20 min. The temperature of the deionized water is 5 °C, accounting for 30% of the total volume of the product barrel. After the discharging is completed, the sulfonated polyether ether ketone is washed with deionized water until it is neutral, and then put into an oven for drying to obtain sulfonated polyether ether ketone; The oven temperature is 60 °C and the drying time is 12 h.

[0020] Example 3 A method for preparing sulfonated polyether ether ketone, comprising: 1. Preparation of modified polyether ether ketone Under nitrogen protection, 4,4'-difluorobenzophenone, hydroquinone, and diphenyl sulfone are added to the reaction kettle. After heating to 190 °C, the catalyst is added, and the temperature is kept for 1.2 h. Then, the PEG-400 solution is added dropwise at 290 °C, and the dropping time is controlled to be 2.5 h. After the dropping is completed, the reaction is carried out at 330 °C for 3.5 h. After the reaction is completed, it is cooled and crystallized, and successively extracted with acetone and washed with deionized water to remove the solvent and inorganic salts to obtain modified polyether ether ketone; The mass ratio of the 4,4'-difluorobenzophenone, hydroquinone, diphenyl sulfone, catalyst, and PEG-400 solution is 63∶23∶137∶50∶26; The mass fraction of the PEG-400 solution is 30%; The catalyst is calcium carbonate.

[0021] 2. Pretreatment After drying the modified polyetheretherketone in an oven to remove moisture, it is ball-milled into a powder with a particle size of 12 μm, and then dissolved and allowed to stand for 40 min in N-methylpyrrolidone to obtain a modified polyetheretherketone solution. The mass ratio of the modified polyetheretherketone to N-methylpyrrolidone is 1.2∶14. The drying temperature is 100 °C and the drying time is 8 h.

[0022] 3. Sulfonation Concentrated sulfuric acid and dichloroethane are added to a reaction kettle, stirring is started, and after preheating to 60 °C, the catalyst FeCl3 is added. Then, the modified polyetheretherketone solution is evenly divided into 10 portions and added to the reaction kettle in batches, with a time interval of 50 min between each batch. After the addition is completed, the temperature is raised to 80 °C and the reaction continues for 10 h until the reaction is completed. The mass ratio of the concentrated sulfuric acid, dichloroethane, FeCl3, and the modified polyetheretherketone solution is 3.5∶1.2∶0.007∶4.3. For the stirring, the initial rate is 200 r / min, and when the catalyst FeCl3 is added, the stirring rate is increased to 1600 r / min.

[0023] 4. Post-treatment The reacted material is discharged through the discharge port of the reaction kettle and put into a product barrel filled with constant-temperature deionized water within 40 min. The temperature of the deionized water is 25 °C, accounting for 40% of the total volume of the product barrel. After the discharging is completed, the sulfonated polyetheretherketone is washed with deionized water until it is neutral, and then put into an oven to be dried to obtain the sulfonated polyetheretherketone. The oven temperature is 100 °C and the drying time is 16 h.

[0024] Example 4 A method for preparing sulfonated polyetheretherketone, on the basis of Example 1, step 1 is deleted, and the modified polyetheretherketone is changed to polyetheretherketone.

[0025] Example 5 A method for preparing sulfonated polyetheretherketone, on the basis of Example 1, the process of dissolving and standing the modified polyetheretherketone powder in N-methylpyrrolidone in step 2 is omitted, and the modified polyetheretherketone solution is changed to the modified polyetheretherketone powder.

[0026] Example 6 A method for preparing sulfonated polyetheretherketone, on the basis of Example 1, the continuous reaction time in step 3 is changed to 12 h.

[0027] Example 7 A method for preparing sulfonated polyether ether ketone, on the basis of Example 1, the continuous reaction time in Step 3 is changed to 15 h.

[0028] Test Example 1. The sulfonated polyether ether ketone prepared in Examples 1 to 7 was tested for sulfonation degree by potentiometric titration. Six groups of samples were randomly taken from each example, and the test results were statistically analyzed, and the average value and deviation were calculated. The larger the average value, the higher the sulfonation degree, and the closer the deviation is to 0, the better the sulfonation uniformity.

[0029] The test results are shown in Table 1: Table 1

[0030] 2. The sulfonated polyether ether ketone prepared in Examples 1 to 7 was used to prepare sulfonated polyether ether ketone membranes by the following method, and the following properties were tested.

[0031] The sulfonated polyether ether ketone powder was dissolved in dimethyl sulfoxide at a concentration of 10% wt, heated to 70 °C and stirred until completely dissolved. The solution was poured onto a clean glass substrate, and the film thickness was controlled to be 80 μm with a scraper. The solvent was volatilized at room temperature for 24 h, and then dried in an oven at 80 °C for 12 h to remove the residual solvent, obtaining a sulfonated polyether ether ketone membrane.

[0032] The test results are shown in Table 2: Table 2

[0033] It can be seen from the above results that in Example 4, the polyether ether ketone was not modified and had poor solubility. In Example 5, the sulfonated polyether ether ketone was not dissolved in N-methylpyrrolidone, the molecular chains were not stretched and swollen, and the contact efficiency with the highly sulfonating agent concentrated sulfuric acid was poor. As a result, the sulfonation degree and sulfonation uniformity of Examples 4 and 5 were low, and the ion exchange capacity of the prepared sulfonated polyether ether ketone membrane was low. Compared with Example 1, Examples 6 and 7 had a longer sulfonation reaction time, and thus a higher sulfonation degree. However, sulfonation at high temperature for a long time would cause degradation of the molecular chains, affecting the sulfonation uniformity. At the same time, the higher the sulfonation degree, the higher the ion exchange capacity of the prepared product, but the tensile strength and thermal decomposition temperature would decrease.

Claims

1. A method for preparing sulfonated polyether ether ketone, characterized in that: The preparation method includes preparing modified polyether ether ketone, pretreatment, sulfonation, and post-treatment; The method for preparing the modified polyether ether ketone is as follows: Under nitrogen protection, add 4,4'-difluorobenzophenone, hydroquinone, and diphenyl sulfone to a reaction kettle. After heating to 170-190 °C, add a catalyst, keep the temperature for 0.8-1.2 h, then dropwise add a PEG-400 solution at 260-290 °C. After the dropping is completed, react at 310-330 °C for 1.5-3.5 h, and then obtain the modified polyether ether ketone through cooling crystallization and washing; The method for the pretreatment is as follows: Dry the modified polyether ether ketone, grind it into powder, dissolve it in N-methylpyrrolidone and let it stand for 20-40 min to obtain a modified polyether ether ketone solution; The method for sulfonation is as follows: Add concentrated sulfuric acid and dichloroethane to a reaction kettle, start stirring, preheat to 40-60 °C, add a catalyst FeCl3, then add the modified polyether ether ketone solution in batches, and then raise the temperature to 70-80 °C and react for 6-10 h to complete the reaction; The method for post-treatment is as follows: Discharge the reacted material through the discharge port of the reaction kettle into a product barrel, wash it to neutral, and dry it to obtain sulfonated polyether ether ketone.

2. The method for preparing sulfonated polyether ether ketone according to claim 1, wherein: In the method for preparing the modified polyether ether ketone, the mass ratio of 4,4'-difluorobenzophenone, hydroquinone, diphenyl sulfone, catalyst, and PEG-400 solution is 59-63:21-23:125-137:46-50:22-26; the mass fraction of the PEG-400 solution is 20-30%; the time for dropping the PEG-400 solution is 1.5-2.5 h; The catalyst is calcium carbonate.

3. A method for preparing sulfonated polyether ether ketone according to claim 1, characterized in that: In the method for the pretreatment, the mass ratio of the modified polyether ether ketone to N-methylpyrrolidone is 0.8-1.2:12-14; the drying temperature is 60-100 °C, the drying time is 6-8 h, and the particle size of the ground powder is 8-12 μm.

4. A method for preparing sulfonated polyether ether ketone according to claim 1, characterized in that: In the method for sulfonation, the method for adding the modified polyether ether ketone solution in batches is to divide the modified polyether ether ketone solution into 6-10 equal parts and add one part to the reaction kettle every 30-50 min.

5. A method for preparing sulfonated polyether ether ketone according to claim 1, characterized in that: In the method for sulfonation, the mass ratio of concentrated sulfuric acid, dichloroethane, FeCl3, and the modified polyether ether ketone solution is 2.5-3.5:0.8-1.2:0.005-0.007:4.1-4.3; Stir, the initial rate is 100-200 r / min, and when the catalyst FeCl3 is added, the stirring rate is increased to 1000-1600 r / min.

6. A method for preparing sulfonated polyether ether ketone according to claim 1, characterized in that: In the method for post-treatment, the discharging time is controlled within 20-40 min, and deionized water is pre-filled in the product barrel, the temperature of the deionized water is 5-25 °C, accounting for 30-40% of the total volume of the product barrel.

7. A method for preparing sulfonated polyether ether ketone according to claim 1, characterized in that: In the method for post-treatment, the oven temperature is 60-100 °C and the drying time is 12-16 h.

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