A high-performance polyethersulfoneetherketoneketone separation membrane resistant to extreme environments and its preparation method

Abstract

The present invention relates to the technical field of polymer materials and their preparation, and provides a high-performance polyethersulfoneetherketoneketone separation membrane resistant to extreme environments and a preparation method thereof, which solves the defect that the separation membranes of the prior art cannot be used in extreme environments. The present invention comprises the following preparation steps: (1) preparing a casting solution; (2) preparing a separation membrane: pouring the casting solution prepared in step (1) onto a clean glass plate, using a manual or automatic scraper to scrape a gel layer at a scraping speed of 50 to 150 mm / s, after volatilization for 3 to 50 seconds, immersing the membrane in a deionized water coagulation bath at 15 to 30°C to solidify into a membrane, and then replacing the coagulation bath every 6 to 8 hours within 24 to 60 hours to fully remove the residual solvent and soluble additives, and finally obtaining a separation membrane with a thickness of 115 to 175 μm.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials and preparation thereof, and in particular to a high-performance polyethersulfoneetherketoneketone separation membrane resistant to extreme environments and a preparation method thereof. Background Art

[0002] With the growing demand for special separation membranes in industrial processes, the research and development of new materials to improve separation efficiency, durability and chemical stability has become an urgent need in the field of separation membranes. At present, the membrane materials used in fine separation processes mainly include polyethersulfone, polyaryletherketone, polyetheretherketone and other high-performance polymers. These materials are widely used in special separation fields such as membrane distillation, gas separation, ultrafiltration and nanofiltration due to their excellent chemical stability, thermal stability and mechanical properties. Although polyetherketoneketone material has been widely studied due to its good chemical corrosion resistance and excellent thermal stability, as a semi-crystalline high-performance polymer, it has a high melting temperature and a low glass transition temperature, has high processing requirements and is difficult to dissolve in solvents. Therefore, there is very little research in the field of separation membranes.

[0003] To address this challenge, a sulfone group was introduced into polyetherketoneketone (PEKK) through molecular design, resulting in PESK. This was synthesized using monomers such as 4,4'-diphenoxydiphenyl sulfone, isophthaloyl chloride, and 4-phenoxybenzoylbiphenyl, using ethylene dichloride, anhydrous aluminum chloride, and dimethyl sulfoxide as catalysts.

[0004] Although polyethersulfoneetherketoneketone (PESEKK) shares a similar aromatic etherketone structure with polymers such as polyetheretherketone (PEEK) and polyetherketoneketone (PEKK), the introduction of a sulfone group into the molecular chain increases its glass transition temperature. This allows PESEKK to possess the same thermal stability and mechanical properties as polyetherketoneketone (PEKK) while also possessing improved chemical resistance and processability, making it soluble in certain solvents. The introduction of the highly polar sulfone group also imparts a more negative charge to the membrane, enabling specific selective separation of dye molecules. However, no researchers or technologies have yet successfully applied PESEKK materials to the preparation of separation membranes, indicating a significant research and commercialization gap in this field.

[0005] Based on the above background, the present invention utilizes the characteristics of polyethersulfoneetherketoneketone material to develop a new type of special separation membrane, specifically a high-performance polyethersulfoneetherketoneketoneketone separation membrane resistant to extreme environments and its preparation method to meet higher standards of industrial separation needs, especially for applications in extreme environments. Summary of the Invention

[0006] Therefore, in response to the above problems, the present invention provides a high-performance polyethersulfoneetherketoneketone separation membrane resistant to extreme environments and a preparation method thereof, which solves the defect that the separation membranes of the prior art cannot be used in extreme environments.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention proposes a separation membrane made of a polyethersulfoneetherketoneketone (PEKK) material. The membrane is prepared by preparing a casting solution of polyethersulfoneetherketoneketone (PEK), a porogen, and a solvent. The casting solution is then applied to a glass plate by a non-solvent-induced phase inversion method, and then immersed in a coagulation bath to obtain a separation membrane with a pore size of 1 to 25 nm and a thickness of 115 to 175 μm. Based on molecular design, the present invention introduces a sulfone group to lower the melting temperature of the polymer and increase the glass transition temperature, thereby making it soluble in certain organic solvents. The prepared PKK separation membrane has excellent properties of high flux, strong alkali resistance, chlorine resistance, and solvent resistance. The introduction of the strongly polar sulfone group also imparts a higher negative charge to the membrane, resulting in specific selective separation performance for dye molecules. Therefore, the membrane can be widely used in coatings, functional membranes, special separation membranes, and water treatment.

[0009] The structural formula of the polyethersulfoneetherketoneketone is shown in the figure below:

[0010]

[0011] n is the degree of polymerization

[0012] A method for preparing a high-performance polyethersulfoneetherketoneketone separation membrane resistant to extreme environments comprises the following preparation steps:

[0013] (1) Preparation of casting solution

[0014] Dissolve 1.00 g of polyethersulfoneetherketoneketone (PEKK) with the following structural formula and 0.2-1.0 g of a porogen in 6-11 ml of a solvent, stir at 20-40° C. for 2-5 hours, then transfer to 5-15° C. and stir for 5-10 hours, then place in a vacuum oven for degassing for 2-10 hours to obtain a uniform casting solution;

[0015]

[0016] n is an integer greater than 160;

[0017] (2) Separation membrane preparation

[0018] The casting solution prepared in step (1) is poured onto a clean glass plate, and a gel layer is scraped at a scraping speed of 50 to 150 mm / s using a manual or automatic scraper. After volatilization for 3 to 50 seconds, the gel layer is immersed in a deionized water coagulation bath at 15 to 30°C to solidify into a membrane. The coagulation bath is then replaced every 6 to 8 hours within 24 to 60 hours to fully remove the residual solvent and soluble additives, and finally a separation membrane with a thickness of 115 to 175 μm is obtained.

[0019] Furthermore: the molecular weight of the polyethersulfoneetherketoneketone is 85000-95000, the intrinsic viscosity is 0.80-0.91, and the particle size range is 50-500 μm.

[0020] Furthermore: the porogen is any one of polyethylene glycol, polyvinyl pyrrolidone, polypropylene glycol, and polyvinyl alcohol, or a mixture of two or more thereof in any ratio.

[0021] Further: the solvent is any one of N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, and N,N-dimethylformamide.

[0022] By adopting the above technical solution, the beneficial effects of the present invention are:

[0023] The polyethersulfoneetherketoneketone separation membrane prepared by the present invention can efficiently retain proteins and dyes, wherein the retention rate of bovine serum albumin (BSA) reaches 99.61±0.23%, the retention rate of Bengal rose red (BR, negative charge, 1017.64Da) reaches 99.16±0.31%, the retention rate of Coomassie brilliant blue R-250 (BBR, negative charge, 825.97Da) reaches 99.17±0.16%, and the retention rate of The membrane achieves a retention rate of 99.72±0.22% for Congo red (CR, negatively charged, 696.66 Da). For a mixed solution consisting of Coomassie Brilliant Blue R-250, Congo red, and Rhodamine B (RhB, positively charged, 479.01 Da), it selectively retains Coomassie Brilliant Blue R-250 and Congo red, while allowing Rhodamine B to permeate the membrane. Furthermore, the membrane maintains relatively stable filtration performance for bovine serum albumin under strong alkaline, chlorine-containing solutions, and solvents. In contrast, a commercial membrane with a similar molecular weight cutoff (Zhongke Ruiyang UE010) corrodes under strong alkaline conditions and experiences a decrease in retention rate in organic solvents. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Graphs showing the permeation flux and BSA rejection of the polyethersulfoneetherketoneketone separation membrane prepared in Example 1 after being immersed in 1 / 3 / 5 / 7 / 9 M sodium hydroxide solutions for 200 h, respectively;

[0025] from Figure 1 It can be seen that the strong alkaline solution has little effect on the separation performance of the polyethersulfoneetherketoneketone separation membrane, and the permeation flux and BSA retention rate remain basically unchanged after soaking.

[0026] Figure 2 Graphs showing the permeation flux and BSA rejection of the polyethersulfoneetherketoneketone separation membrane prepared in Example 1 after being immersed in 50 / 100 / 150 / 200 mg / L sodium hypochlorite solutions for 200 h;

[0027] from Figure 2It can be seen that the strong alkaline solution has little effect on the separation performance of the polyethersulfoneetherketoneketone separation membrane, and the permeation flux and BSA retention rate remain basically unchanged after soaking.

[0028] Figure 3 These are scanning electron micrographs of the polyethersulfoneetherketoneketone separation membrane prepared in Example 1 after being immersed in a sodium hydroxide solution and a sodium hypochlorite solution for 200 h, respectively, wherein (a)-(c) are surface morphologies of the membrane, and (d)-(f) are cross-sectional views of the membrane;

[0029] from Figure 3 It can be seen that the surface morphology and internal structure of the polyethersulfoneetherketoneketone separation membrane after soaking in sodium hydroxide solution and sodium hypochlorite solution have no obvious changes, which shows that the polyethersulfoneetherketoneketone separation membrane has excellent strong alkali and chlorine resistance.

[0030] Figure 4 This is a scanning electron micrograph of a commercial membrane (Zhongke Ruiyang UE010) after being immersed in a 9M sodium hydroxide solution for 200 h;

[0031] from Figure 4 It can be seen that the surface of the commercial membrane is corroded and the structure inside the membrane is severely damaged.

[0032] Figure 5 Graphs showing the permeation flux and BSA rejection of the polyethersulfoneetherketoneketone separation membrane prepared in Example 2 after being immersed in deionized water, n-hexane, isopropanol, and methanol for 200 hours, respectively;

[0033] It can be seen from the figure that n-hexane, isopropanol and methanol have little effect on the separation performance of the polyethersulfoneetherketoneketone separation membrane, and the permeation flux and BSA retention rate after immersion are still maintained at about 95%.

[0034] Figure 6 These are scanning electron micrographs of the polyethersulfoneetherketoneketone separation membrane prepared in Example 2 after being immersed in n-hexane, isopropanol, and methanol for 200 h, respectively. (a)-(c) are surface morphologies of the membrane, and (d)-(f) are cross-sectional views of the membrane.

[0035] from Figure 6 It can be seen that the surface morphology and internal structure of the polyethersulfoneetherketoneketone separation membrane after soaking in n-hexane, isopropanol and methanol have no obvious changes, which shows that the polyethersulfoneetherketoneketone separation membrane has excellent solvent resistance.

[0036] Figure 7 The infrared spectra of the polyethersulfoneetherketoneketone separation membranes prepared in Example 1 and Example 2 were tested after being immersed in sodium hydroxide, sodium hypochlorite and solvent respectively;

[0037] from Figure 7It can be seen that the chemical structure of the membrane does not change after being soaked in sodium hydroxide, sodium hypochlorite and solvent, showing excellent resistance to strong alkali, chlorine and solvent.

[0038] Figure 8 Figures 1 and 2 show the permeability and selectivity of the polyethersulfoneetherketoneketone separation membrane prepared in Example 3 for filtering three dyes, namely, Rose Bengal, Coomassie Brilliant Blue R-250, and Congo Red;

[0039] from Figure 8 It can be seen that the polyethersulfoneetherketoneketone separation membrane still has a large permeation flux during filtration, and can achieve efficient retention of molecules of different molecular weights, with a retention rate of more than 99%.

[0040] Figure 9 This is a UV spectrum scan of the polyethersulfoneetherketoneketone separation membrane prepared in Example 4 used to filter a mixed dye solution of Coomassie Brilliant Blue R-250, Congo Red, and Rhodamine B;

[0041] from Figure 9 It can be seen that the polyethersulfoneetherketoneketone separation membrane can selectively retain the negatively charged Coomassie Brilliant Blue R-250 and Congo Red (retention rate is as high as over 99%), while allowing the positively charged Rhodamine B to pass through the membrane (retention rate is less than 5%), showing excellent dye selective separation performance.

[0042] Figure 10 1 is a graph showing the pure water flux and BSA rejection of the polyethersulfoneetherketoneketone separation membranes prepared in Examples 1-4;

[0043] from Figure 10 It can be seen from the figure that as the content of polyethersulfoneetherketoneketone increases in Examples 1 to 4, the pure water flux gradually decreases and the BSA retention rate gradually increases. This is the result of the combined effect of the increase in the thickness of the dense layer on the surface of the polyethersulfoneetherketoneketone separation membrane and the decrease in the membrane pore size. DETAILED DESCRIPTION

[0044] The present invention is described in further detail below with reference to specific embodiments.

[0045] Example 1

[0046] Weigh 1.00g of polyethersulfoneetherketoneketone and 0.46g of polyvinylpyrrolidone are dissolved in 6.06ml of N-methylpyrrolidone, stirred at 25°C for 3h, then transferred to 10°C and stirred for 7h to prepare a homogeneous casting solution. The casting solution is then degassed in a vacuum oven for 6h and poured onto a clean glass plate. A manual scraper is used to scrape the gel layer at a scraping speed of 100mm / s. After 20s of volatilization, it is immersed in a 25°C deionized water coagulation bath to solidify into a film. The coagulation bath is then replaced every 6h within 48h to fully remove the residual solvent and soluble additives. Finally, a separation membrane with a thickness of 120±5μm is prepared.

[0047] The polyethersulfoneetherketoneketone separation membrane prepared in Example 1 was analyzed by electron microscopy. The membrane had excellent film-forming properties, a smooth and dense membrane surface, which was conducive to the interception of pollutants. The membrane structure was an asymmetric finger-like pore structure, which was conducive to the rapid transmission of water molecules. The prepared membrane was tested for its water flux and retention rate using a cross-flow filtration device. When the operating pressure was 1 bar, the pure water flux of the membrane was about 652.54 Lm -2 h -1 bar -1 Subsequently, bovine serum albumin was used as a simulated pollutant, and its retention rate was measured to be approximately 92.81%, demonstrating excellent protein retention performance.

[0048] The polyethersulfoneetherketoneketone separation membrane prepared in Example 1 was immersed in 1 / 3 / 5 / 7 / 9M sodium hydroxide solution and 50 / 100 / 150 / 200mg / L sodium hypochlorite solution for 200h, and its bovine serum albumin retention rate (such as Figure 1 、 Figure 2 ) remains above 95% and the permeate flux does not change significantly. The membrane soaked in isopropanol and methanol may have a slight swelling phenomenon, which leads to a slight increase in the permeate flux, but has little effect on the retention rate. Figure 3 , it can be observed under an electron microscope that the membrane structure has hardly changed after being immersed in sodium hydroxide and sodium hypochlorite solutions, such as Figure 7 After soaking in sodium hydroxide and sodium hypochlorite solutions, the chemical structure of the membrane did not change significantly, proving that the polyethersulfoneetherketoneketone material gives the separation membrane excellent resistance to strong alkali and chlorine. However, the same type of commercial membrane (Zhongke Ruiyang UE010) becomes thinner after soaking in sodium hydroxide solution. Figure 4 The SEM image shows that the membrane structure has been destroyed and the membrane surface has been corroded. The BSA retention rate has dropped by 71.95%.

[0049] Example 2

[0050] The method is basically the same as Example 1, except that the amount of polyvinyl pyrrolidone is changed to 0.40 g, and the amount of N-methyl pyrrolidone is changed to 5.13 ml. Finally, a separation membrane with a thickness of 123±5 μm is prepared.

[0051] The separation membrane prepared in Example 2 was tested for its water flux and retention rate using a cross-flow filtration device. When the operating pressure was 1 bar, the pure water flux of the membrane was approximately 552.59 Lm -2 h -1 bar -1 Subsequently, bovine serum albumin was used as a simulated pollutant, and its retention rate was measured to be approximately 97.40%, demonstrating excellent protein retention performance.

[0052] The polyethersulfoneetherketoneketone separation membrane prepared in Example 2 was immersed in n-hexane, isopropanol and methanol for 200 h, and its bovine serum albumin retention rate was measured after multiple washings with deionized water (e.g. Figure 5 ) remained at around 95%, and the permeation flux was relatively stable; while the same type of commercial membrane (Zhongke Ruiyang UE010) increased its rejection by 5.11% to 10.09% and its permeation flux decreased by 19.37% to 47.92% after being soaked in three organic solvents. Figure 6 , it can be observed under an electron microscope that the membrane structure has almost no change after being immersed in the solvent, such as Figure 7 As shown in the infrared spectrum, the chemical structure of the membrane did not change significantly after soaking in n-hexane, isopropanol and methanol, proving that the polyethersulfoneetherketoneketone material gives the separation membrane excellent solvent resistance.

[0053] Example 3:

[0054] The method is basically the same as Example 1, except that the amount of polyvinyl pyrrolidone is changed to 0.35 g, and the amount of N-methyl pyrrolidone is changed to 4.41 ml. Finally, a separation membrane with a thickness of 126±5 μm is prepared.

[0055] The separation membrane prepared in Example 3 was tested for its water flux and retention rate using a cross-flow filtration device. When the operating pressure was 1 bar, the pure water flux of the membrane was approximately 317.67 Lm -2 h -1 bar -1 Subsequently, bovine serum albumin was used as a simulated pollutant, and its retention rate was measured to be approximately 99.07%, demonstrating excellent protein retention performance.

[0056] The separation membrane prepared in Example 3 was tested for its dye retention performance using a cross-flow filtration device. Figure 8As shown in the results, the separation membrane has a rejection rate of up to 99.69±0.31% for Rose Bengal (BR), 99.17±0.16% for Coomassie Brilliant Blue R-250 (BBR), and 99.72±0.22% for Congo Red (CR), showing excellent dye retention performance.

[0057] Example 4:

[0058] The method is basically the same as Example 1, except that the amount of polyvinyl pyrrolidone is changed to 0.32 g, and the amount of N-methyl pyrrolidone is changed to 3.84 ml. Finally, a separation membrane with a thickness of 129±5 μm is prepared.

[0059] The separation membrane prepared in Example 4 was tested for its water flux and retention rate using a cross-flow filtration device. When the operating pressure was 1 bar, the pure water flux of the membrane was approximately 76.39 Lm -2 h -1 bar -1 Subsequently, bovine serum albumin was used as a simulated pollutant, and its retention rate was measured to be approximately 99.61%, demonstrating excellent protein retention performance.

[0060] The separation membrane prepared in Example 4 was tested for its dye selective separation performance using a cross-flow filtration device. Figure 9 As shown in the figure, the ultraviolet spectrum scanning diagram of the permeate is basically consistent with that of rhodamine B, indicating that the separation membrane can selectively retain negatively charged Coomassie Brilliant Blue R-250 and Congo Red (retention rate is as high as over 99%), while allowing positively charged rhodamine B to pass through the membrane (retention rate is less than 5%), showing excellent dye selective separation performance.

[0061] Although the present invention has been particularly shown and described in conjunction with preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made to the present invention without departing from the spirit and scope of the invention as defined in the appended claims, and all such changes are within the scope of protection of the present invention.

Claims

1. A method for preparing a high-performance polyethersulfoneetherketoneketone separation membrane resistant to extreme environments, characterized by: The method comprises the following preparation steps: (1) Preparation of casting solution Dissolve 1.00 g of polyethersulfoneetherketoneketone (PEKK) of the following structural formula and 0.2-1.0 g of a porogen in 6-11 mL of a solvent, stir at 20-40° C. for 2-5 hours, then transfer to 5-15° C. and stir for 5-10 hours, then place in a vacuum oven for degassing for 2-10 hours to obtain a uniform casting solution; n is an integer greater than 160; (2) Separation membrane preparation The casting solution prepared in step (1) is poured onto a clean glass plate, and a gel layer is scraped at a scraping speed of 50 to 150 mm / s using a manual or automatic scraper. After volatilization for 3 to 50 seconds, the gel layer is immersed in a deionized water coagulation bath at 15 to 30°C to solidify into a membrane. The coagulation bath is then replaced every 6 to 8 hours within 24 to 60 hours to fully remove the residual solvent and soluble additives, and finally a separation membrane with a thickness of 115 to 175 μm is obtained.

2. The method for preparing a high-performance polyethersulfoneetherketoneketone separation membrane resistant to extreme environments according to claim 1, characterized in that: The polyethersulfoneetherketoneketone has a molecular weight of 85,000 to 95,000, an intrinsic viscosity of 0.80 to 0.91, and a particle size range of 50 to 500 μm.

3. The method for preparing a high-performance polyethersulfoneetherketoneketone separation membrane resistant to extreme environments according to claim 1, characterized in that: The porogen is any one of polyethylene glycol, polyvinyl pyrrolidone, polypropylene glycol, and polyvinyl alcohol, or a mixture of two or more thereof in any ratio.

4. The method for preparing a high-performance polyethersulfoneetherketoneketone separation membrane resistant to extreme environments according to claim 1, characterized in that: The solvent is any one of N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, and N,N-dimethylformamide.

5. A high-performance polyethersulfoneetherketoneketone separation membrane resistant to extreme environments, characterized by: The membrane is prepared by the method for preparing a high-performance polyethersulfoneetherketoneketone separation membrane resistant to extreme environments as described in claim 1.

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