Polyethersulfone membrane with highly asymmetric structure and preparation method and application thereof

Abstract

The present invention provides a polyethersulfone membrane with a highly asymmetric structure and a preparation method and application thereof, and relates to the field of material technology. The preparation method of the polyethersulfone membrane with a highly asymmetric structure provided by the present invention comprises: applying a casting liquid into a liquid film, then immersing the liquid film in a coagulation bath to solidify into a film, and then washing with water to prepare a polyethersulfone membrane with a highly asymmetric structure. The preparation method has a simple process, is prepared by only one casting liquid, is integrally formed, does not require a multi-layer composite preparation process, and is easy to scale up; the selective separation layer and porous support layer structure of the polyethersulfone membrane are controlled by regulating the casting liquid formula and process parameters, thereby obtaining a polyethersulfone membrane with different asymmetric structures, which provides a new idea for reducing the Trade-off effect of the ultrafiltration membrane; the prepared polyethersulfone membrane can be applied to the separation and purification of proteins or viruses to meet the needs of practical applications.

Description

Technical Field

[0001] The invention relates to the technical field of materials, and in particular to a polyethersulfone membrane with a highly asymmetric structure and a preparation method and application thereof. Background Art

[0002] Polyethersulfone (PES) polymer materials are widely used to prepare ultrafiltration membranes due to their excellent chemical inertness, thermodynamic stability and mechanical strength, and are then used in separation and purification in the biological and medical fields. However, the permselective separation performance of ultrafiltration membranes is mainly affected by the membrane pore size and membrane structure. In order to obtain ultrafiltration membranes that take into account both high flux and high retention rate, highly asymmetric membranes with dense surfaces and porous bottoms are one of the current research hotspots in the field of membrane separation. At the same time, in the process of biomedical separation and purification, the fine pore size of the ultrafiltration membrane cortex is mainly used to filter and intercept viruses to ensure the safety of biological products; in addition, the ultrafiltration membrane cortex pore size will also be used to concentrate the protein solution from which the virus has been removed to meet the concentration requirements of subcutaneous injections. Therefore, although the traditional finger-like pore ultrafiltration membrane has good permeability, its bottom is a large cavity structure, which makes it have no advantages in biological safety and mechanical strength; and although the sponge-like pore structure has the characteristics of gradient pore structure and excellent pressure resistance, this type of structure is often limited by the dense cortex of the ultrafiltration membrane, so that the prepared membrane has a small degree of structural asymmetry, showing the disadvantages of low flux and low loading. Therefore, it is of great practical value to prepare an ultrafiltration membrane with high asymmetry and adjustable membrane pore gradient.

[0003] At present, the common method for preparing ultrafiltration membranes is to prepare a membrane in one piece after a single layer is cast, but the asymmetric structure of the prepared membrane is not obvious. In order to prepare an ultrafiltration membrane with a highly asymmetric structure, Chinese patents CN1759924B, CN116747721A, and CN117282280B all disclose an asymmetric composite ultrafiltration membrane with a multilayer structure. The above-mentioned composite ultrafiltration membranes are prepared with at least two different casting solutions, and in the preparation process, a slot die coating machine is used for co-casting or the thickness of the scraper is adjusted to scrape different membrane liquid layers in sequence. Although this type of technology can be used to prepare a composite ultrafiltration membrane with a separation layer that takes into account the filtration accuracy and a support layer for the filtration flow rate. However, this technology has very significant disadvantages in the membrane preparation process: different layers are easy to delaminate, and there is an easy formation of skin between layers, and there is an obvious dividing line; while controlling the multilayer structure, the phase separation process is more complicated, and the process is more difficult to control.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The first object of the present invention is to provide a method for preparing a polyethersulfone membrane with a highly asymmetric structure to solve the above technical problems.

[0006] The second object of the present invention is to provide a polyethersulfone membrane with a highly asymmetric structure.

[0007] The third object of the present invention is to provide the use of the polyethersulfone membrane with a highly asymmetric structure in protein or virus filtration.

[0008] In order to achieve the above objectives, the following technical solutions are adopted:

[0009] In a first aspect, the present invention provides a method for preparing a polyethersulfone membrane with a highly asymmetric structure, comprising the following steps:

[0010] The casting liquid is coated into a liquid film, and then the liquid film is immersed in a coagulation bath to solidify into a film, and then washed with water to prepare a polyethersulfone membrane with a highly asymmetric structure;

[0011] The casting solution comprises, by mass percentage, 15% to 20% polyethersulfone, 40% to 60% non-solvent, and the remainder is a good solvent;

[0012] The non-solvent is at least one of glycerol ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether or diethylene glycol monoethyl ether;

[0013] The good solvent includes at least one of N-N dimethylformamide, N-N dimethylacetamide, N-methylpyrrolidone or dimethyl sulfoxide;

[0014] The coagulation bath comprises a good solvent and water, wherein the mass proportion of the good solvent is 10% to 70%; the temperature of the coagulation bath is 20 to 50°C.

[0015] As a further technical solution, the casting solution also includes a hydrophilic additive.

[0016] As a further technical solution, the hydrophilic additive includes at least one of polyvinyl pyrrolidone, polyethylene glycol, chitosan, polyvinyl alcohol, dextran, lithium chloride or lithium perchlorate.

[0017] As a further technical solution, in the casting solution, the mass proportion of the hydrophilic additive is less than or equal to 4%.

[0018] As a further technical solution, a scraper is used to apply a liquid film on the carrier.

[0019] As a further technical solution, during the liquid film coating process, the ambient temperature is 20-25°C and the humidity is 40RH%-70RH%.

[0020] As a further technical solution, the liquid film is immersed in the coagulation bath for 1 to 10 minutes.

[0021] In a second aspect, the present invention provides a polyethersulfone membrane with a highly asymmetric structure, which is prepared by the above-mentioned preparation method.

[0022] As a further technical solution, the polyethersulfone membrane comprises a selective separation layer and a porous support layer;

[0023] The thickness of the selective separation layer is 200-500 nm;

[0024] The thickness of the polyethersulfone membrane is 100-150 μm.

[0025] In a third aspect, the present invention provides the use of the above-mentioned highly asymmetric polyethersulfone membrane in protein or virus filtration.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The preparation method of the polyethersulfone membrane with a highly asymmetric structure provided by the present invention has a simple process, is prepared by only one casting liquid, is integrally formed, does not require a multi-layer composite preparation process, and is easy to scale up; the selective separation layer and the porous support layer structure of the polyethersulfone membrane are controlled by regulating the casting liquid formula and process parameters, thereby obtaining a polyethersulfone membrane with different asymmetric structures, which provides a new idea for reducing the trade-off effect of the ultrafiltration membrane; the prepared polyethersulfone membrane can be used for the separation and purification of proteins or viruses, meeting practical application needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 A cross-sectional view of the PES ultrafiltration membrane provided in Example 1 of the present invention, at a magnification of 5000x;

[0030] Figure 2 A cross-sectional view of the PES ultrafiltration membrane provided for Comparative Example 1, at a magnification of 1000x;

[0031] Figure 3 A cross-sectional view of the PES ultrafiltration membrane provided for Comparative Example 2, at a magnification of 1000x;

[0032] Figure 4 A cross-sectional view of a PES ultrafiltration membrane provided in Example 2 of the present invention, at a magnification of 2000x;

[0033] Figure 5This is a surface electron microscope image of the PES ultrafiltration membrane support layer provided in Example 2 of the present invention, with a magnification of 2000x;

[0034] Figure 6 This is a surface electron microscope image of the separation layer of the PES ultrafiltration membrane provided in Example 2 of the present invention, with a magnification of 3000x;

[0035] Figure 7 A cross-sectional view of the PES ultrafiltration membrane provided for Comparative Example 3, at a magnification of 2000x;

[0036] Figure 8 This is a cross-sectional view of the PES ultrafiltration membrane provided for Comparative Example 4, with a magnification of 2000x. DETAILED DESCRIPTION

[0037] The embodiments of the present invention will be described in detail below in conjunction with the embodiments and examples, but it will be appreciated by those skilled in the art that the following embodiments and examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified, proceed according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0038] In a first aspect, the present invention provides a method for preparing a polyethersulfone membrane with a highly asymmetric structure, comprising the following steps:

[0039] The casting liquid is coated into a liquid film, and then the liquid film is immersed in a coagulation bath to solidify into a film, and then washed with water to prepare a polyethersulfone membrane with a highly asymmetric structure;

[0040] The casting solution includes polyethersulfone, a non-solvent and a good solvent, wherein the mass proportion of polyethersulfone can be, for example, but not limited to 15%, 16%, 17%, 18%, 19% or 20%, and the mass proportion of the non-solvent can be, for example, but not limited to 40%, 45%, 50%, 55% or 60%;

[0041] The non-solvent is at least one of glycerol ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether or diethylene glycol monoethyl ether;

[0042] The good solvent is not limited to at least one of N N dimethylformamide, N N dimethylacetamide, N-methylpyrrolidone or dimethyl sulfoxide;

[0043] The coagulation bath includes a good solvent and water, wherein the mass proportion of the good solvent is 10% to 70%, for example, it can be, but not limited to, 10%, 30%, 50% or 70%; the temperature of the coagulation bath can be, for example, but not limited to, 20°C, 30°C, 40°C or 50°C.

[0044] In the phase separation process, common organic solvents are easily soluble in the non-solvent in the coagulation bath to produce instantaneous phase separation, making it easier for polyethersulfone to precipitate, and finally forming a PES porous membrane with a thick selective separation layer and a small pore size gradient change. In the present invention, a specific ether substance is used as a non-solvent, which can effectively control the viscosity of the casting liquid system. At the same time, in the phase separation process, through the interaction with the coagulation bath, the diffusion speed of the non-solvent in the coagulation bath into the liquid film is slowed down, which makes the phase separation time longer, which is conducive to the formation of a loose and porous sponge-like pore structure.

[0045] The preparation method provided by the present invention optimizes the composition and conditions of the coagulation bath so that the liquid membrane can obtain an ultrafiltration membrane with an ideal membrane pore size and a highly asymmetric structure under the joint action of the coagulation bath and the casting liquid system.

[0046] In some optional embodiments, the casting solution further includes a hydrophilic additive.

[0047] In some optional embodiments, the hydrophilic additive includes but is not limited to at least one of polyvinyl pyrrolidone, polyethylene glycol, chitosan, polyvinyl alcohol, dextran, lithium chloride or lithium perchlorate, or other hydrophilic additives known to those skilled in the art to improve the hydrophilicity of the filter membrane.

[0048] In some optional embodiments, in the casting solution, the mass proportion of the hydrophilic additive is less than or equal to 4%, for example, it can be, but not limited to, 1%, 2%, 3% or 4%.

[0049] In some optional embodiments, a doctor blade is used to apply the liquid film on the carrier.

[0050] In some optional embodiments, the carrier may be, for example, glass, steel plate, etc.

[0051] The present invention has no special requirements for the ambient temperature and humidity of the coating film. In some optional embodiments, during the liquid film coating process, the ambient temperature can be, for example, but not limited to 20°C, 21°C, 22°C, 23°C, 24°C or 25°C, and the humidity can be, for example, but not limited to 40RH%, 50RH%, 60RH% or 70RH%.

[0052] In some optional embodiments, the time for which the liquid film is immersed in the coagulation bath may be, for example, but not limited to, 1 min, 2 min, 4 min, 6 min, 8 min or 10 min.

[0053] In a second aspect, the present invention provides a polyethersulfone membrane with a highly asymmetric structure, which is prepared by the above-mentioned preparation method.

[0054] The polyethersulfone membrane can be used for separation and purification of proteins or viruses. For example, a membrane with a smaller pore size can be used for interception of BSA, and a membrane with a larger pore size can be used for separation of a mixture of viruses and proteins, that is, intercepting viruses and passing proteins.

[0055] It should be noted that for the retention of BSA, it is preferred to use a separation layer facing the feed liquid; for the retention of viruses, it is preferred to use a support layer facing the feed liquid. The purpose of this is that the porous support layer can pre-filter the polymers in the protein solution, thereby ensuring a high permeability of the protein.

[0056] In some optional embodiments, the polyethersulfone membrane comprises a selective separation layer and a porous support layer;

[0057] The thickness of the selective separation layer is 200-500 nm;

[0058] The thickness of the polyethersulfone membrane is 100-150 μm.

[0059] In a third aspect, the present invention provides the use of the above-mentioned highly asymmetric polyethersulfone membrane in protein or virus filtration.

[0060] The present invention is further described below by means of specific examples and comparative examples. However, it should be understood that these examples are only used for more detailed description and should not be construed as limiting the present invention in any form.

[0061] Example 1

[0062] Mix 18wt% PES, 3wt% polyethylene glycol, 40wt% propylene glycol monomethyl ether and 39wt% N-methylpyrrolidone, stir, stand and degas at room temperature to obtain a clear, uniform and stable casting solution. Pour the casting solution onto a clean glass carrier, use a 300um scraper to scrape the casting solution into a thin film, and through immersion phase transformation, put the scraped cast film into a coagulation bath of 10wt% N-methylpyrrolidone and 90wt% deionized water, where the temperature of the coagulation bath is room temperature and the residence time is 1min, and then transfer it to pure water. After the membrane falls off automatically, place the scraped PES ultrafiltration membrane in deionized water and soak for 12 hours to ensure that the residual organic solvent in the membrane pores is completely removed, and then soak it in a glycerol solution and dry it to obtain the PES ultrafiltration membrane. Figure 1 shown.

[0063] Example 2

[0064] Mix 15wt% PES, 3wt% chitosan, 60wt% ethylene glycol monomethyl ether and 22wt% NN dimethylacetamide, stir, stand and degas at room temperature to obtain a clear, uniform and stable casting solution. Pour the casting solution onto a clean glass carrier, use a 300um scraper to scrape the casting solution into a thin film, and through immersion phase transformation, place the scraped cast membrane into a coagulation bath of 60wt% NN dimethylacetamide and 40wt% deionized water, where the temperature of the coagulation bath is 35°C and the residence time is 5min, and then transfer it to pure water. After the membrane falls off automatically, place the scraped PES ultrafiltration membrane in deionized water and soak for 12 hours to ensure that the residual organic solvent in the membrane pores is completely removed, and then soak it in a glycerol solution and dry it to obtain the PES ultrafiltration membrane. Figure 4-Figure 6 shown.

[0065] Example 3

[0066] 20wt% PES, 50wt% glycerol ether and 30wt% dimethyl sulfoxide were mixed, stirred, allowed to stand and degassed at room temperature to obtain a clear, uniform and stable casting solution. The casting solution was poured onto a clean glass carrier, and a 300um scraper was used to scrape the casting solution into a thin film. Through immersion phase transformation, the scraped cast film was placed in a coagulation bath of 70wt% dimethyl sulfoxide and 30wt% deionized water, where the temperature of the coagulation bath was 50℃ and the residence time was 10min, and then it was transferred to pure water. After the membrane automatically fell off, the scraped PES ultrafiltration membrane was placed in deionized water and soaked for 12 hours to ensure that the residual organic solvent in the membrane pores was completely removed, and then soaked in a glycerol solution and dried to obtain a PES ultrafiltration membrane.

[0067] Example 4

[0068] 15wt% PES, 3wt% polyvinyl pyrrolidone, 60wt% ethylene glycol monoethyl ether and 22wt% NN dimethylformamide were mixed, stirred, allowed to stand and degassed at room temperature to obtain a clear, uniform and stable casting solution. The casting solution was poured onto a clean glass carrier, and a 300um scraper was used to scrape the casting solution into a thin film. Through immersion phase transformation, the scraped cast film was placed in a coagulation bath of 60wt% NN dimethylacetamide and 40wt% deionized water, where the temperature of the coagulation bath was 35℃ and the residence time was 5min, and then it was transferred to pure water. After the membrane automatically fell off, the scraped PES ultrafiltration membrane was placed in deionized water and soaked for 12 hours to ensure that the residual organic solvent in the membrane pores was completely removed, and then soaked in a glycerol solution and dried to obtain a PES ultrafiltration membrane.

[0069] Example 5

[0070] 15wt% PES, 3wt% polyvinyl alcohol, 60wt% diethylene glycol monomethyl ether and 22wt% NN dimethylacetamide were mixed, stirred, allowed to stand and degassed at room temperature to obtain a clear, uniform and stable casting solution. The casting solution was poured onto a clean glass carrier, and a 300um scraper was used to scrape the casting solution into a thin film. Through immersion phase transformation, the scraped cast film was placed in a coagulation bath of 60wt% NN dimethylacetamide and 40wt% deionized water, where the temperature of the coagulation bath was 35℃ and the residence time was 5min, and then it was transferred to pure water. After the membrane automatically fell off, the scraped PES ultrafiltration membrane was placed in deionized water and soaked for 12 hours to ensure that the residual organic solvent in the membrane pores was completely removed, and then soaked in a glycerol solution and dried to obtain a PES ultrafiltration membrane.

[0071] Example 6

[0072] 15wt% PES, 3wt% lithium chloride, 60wt% diethylene glycol monoethyl ether and 22wt% NN dimethylacetamide were mixed, stirred, allowed to stand and degassed at room temperature to obtain a clear, uniform and stable casting solution. The casting solution was poured onto a clean glass carrier, and a 300um scraper was used to scrape the casting solution into a thin film. Through immersion phase transformation, the scraped cast film was placed in a coagulation bath of 60wt% NN dimethylacetamide and 40wt% deionized water, where the temperature of the coagulation bath was 35℃ and the residence time was 5min, and then it was transferred to pure water. After the membrane automatically fell off, the scraped PES ultrafiltration membrane was placed in deionized water and soaked for 12 hours to ensure that the residual organic solvent in the membrane pores was completely removed, and then soaked in a glycerol solution and dried to obtain a PES ultrafiltration membrane.

[0073] Comparative Example 1

[0074] 18wt% PES, 3wt% polyethylene glycol and 79wt% N-methylpyrrolidone are stirred, allowed to stand and degassed at room temperature to obtain a clear, uniform and stable casting solution. The casting solution is poured onto a clean glass carrier, and a 300um scraper is used to scrape the casting solution into a thin film. Through immersion phase transformation, the scraped cast membrane is placed in a coagulation bath of 10wt% N-methylpyrrolidone and 90wt% deionized water, wherein the temperature of the coagulation bath is room temperature and the residence time is 1min, and then it is transferred to a pure water bath. After the membrane falls off automatically, the scraped PES ultrafiltration membrane is placed in deionized water and soaked for 12 hours to ensure that the residual organic solvent in the membrane pores is completely removed, and then it is placed in a glycerol solution for soaking and drying to obtain the PES ultrafiltration membrane. Figure 2 It can be seen that since there is no non-solvent in the casting solution system of this comparative example, the prepared membrane presents a finger-like pore structure.

[0075] Comparative Example 2

[0076] Mix 18wt% PES, 3wt% polyethylene glycol, 10wt% propylene glycol monomethyl ether and 69wt% N-methylpyrrolidone, stir, stand and degas at room temperature to obtain a clear, uniform and stable casting solution. Pour the casting solution onto a clean glass carrier, use a 300um scraper to scrape the casting solution into a thin film, and through immersion phase transformation, put the scraped cast film into a coagulation bath of 10wt% N-methylpyrrolidone and 90wt% deionized water, where the temperature of the first coagulation bath is room temperature and the residence time is 1min, and then transfer it to a pure water bath. After the membrane falls off automatically, place the scraped PES ultrafiltration membrane in deionized water and soak for 12 hours to ensure that the residual organic solvent in the membrane pores is completely removed, and then soak it in a glycerol solution and dry it to obtain the PES ultrafiltration membrane. Figure 3 It can be seen that, due to the low content of the non-solvent in the casting solution system of this comparative example, the proportion of the sponge-like pore structure in the cross-sectional structure of the membrane increases, but a uniform sponge-like pore structure cannot be formed.

[0077] Comparative Example 3

[0078] Dissolve 15wt% PES, 3wt% chitosan, and 60wt% ethylene glycol monomethyl ether in 22wt% NN dimethylacetamide, stir, stand, and degas at room temperature to obtain a clear, uniform, and stable casting solution. Pour the casting solution onto a clean glass carrier, use a 300um scraper to scrape the casting solution into a thin film, and place the scraped cast film into a deionized water coagulation bath through immersion phase transformation. After the film falls off automatically, place the scraped PES ultrafiltration membrane in deionized water and soak for 12 hours to ensure that the residual organic solvent in the membrane pores is completely removed, and then soak in a glycerol solution and dry to obtain a PES ultrafiltration membrane. Figure 7 The difference between this comparative example and Example 2 is that the coagulation bath is water. When pure water is used as the coagulation bath, an asymmetric sponge-like pore structure can be prepared, but the dense cortex of the membrane prepared under this condition is very thick, resulting in very low permeability of the membrane. At the same time, the membrane pores are small and easily retain IgG proteins, resulting in high loss of the target product.

[0079] Comparative Example 4

[0080] The difference from Example 2 is that polyethylene glycol is used as a non-solvent. Figure 8 As shown in the figure, it can be seen that when PEG is used as a non-solvent, the prepared membrane has a partial finger-like pore structure in its cross-sectional structure. The membrane with a finger-like pore structure is used in virus removal filtration, but the presence of macropore defects will cause virus leakage, thus failing to effectively remove the virus.

[0081] Test example

[0082] The filter membranes prepared in the above examples and comparative examples were tested respectively, and the results are as follows:

[0083] 1g / L BSA retention rate and IgG protein permeability determination:

[0084] The ultrafiltration membrane water flux and membrane protein retention rate were tested according to the test standards in the national standard GB / T 32360 2015. The specific steps are as follows: First, the completely wetted membrane sample was installed in the tangential flow test device, the membrane sample was pre-pressed at a pressure of 0.15 MPa for 30 min, and then the test pressure was adjusted to 0.10 MPa. The mass change of pure water passing through the ultrafiltration membrane was recorded at this pressure, and the test process lasted for 30 min. Using 1 g / L BSA solution as the feed solution, the membrane retention rate of BSA was measured at 0.1 MPa, and the concentration of BSA was measured by ultraviolet spectrophotometer. In addition, the IgG test can also be carried out as described above for the determination of the standard curve and the test of the corresponding concentration.

[0085] Virus retention rate test:

[0086] The method for determining the virus retention rate can refer to patents CN1759924B-Ultrafiltration membrane and its preparation method, CN112074340-Porous hollow fiber membrane. The cultured bacteriophage PP7 stock solution was diluted to about 4.0×10 6 The PFU / mL concentration is used as the virus feed solution, and the dilution solution used is phosphate buffer. Here, the phosphate buffer is a solution sterilized with high-pressure steam at 121°C for 20 min. At room temperature, a certain pressure (such as 0.2 MPa) is applied to perform the retention test. Discard the 10 mL of filtrate collected at the beginning of the filtration, and then collect another 10 mL of filtrate to evaluate the removal rate of the test membrane for bacteriophages. The collected filtrate and the virus feed solution are cultured, and the double-layer plate counting method is used to compare the plaques formed by the phage solution on the double-layer plate before and after interception, and then the separation performance of the membrane is evaluated. The plaque refers to a group of bacteria infected with the virus and dead, which can be counted as a dot-like lytic plaque. The virus removal performance is expressed by the logarithmic virus removal rate (LRV), and the calculation formula is as follows:

[0087] LRV=log 10 [C filtrate / C feed ].

[0088] Among them, C filtrate is the concentration of virus in the filtrate, C feed is the concentration of virus in the stock solution.

[0089] Table 1

[0090] .

[0091] Note: NA means not applicable.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a polyethersulfone membrane with a highly asymmetric structure, characterized in that: The following steps are involved: The casting liquid is coated into a liquid film, and then the liquid film is immersed in a coagulation bath to solidify into a film, and then washed with water to prepare a polyethersulfone membrane with a highly asymmetric structure; The casting solution comprises, by mass percentage, 15% to 20% polyethersulfone, 40% to 60% non-solvent, and the remainder is a good solvent; The non-solvent is at least one of glycerol ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether or diethylene glycol monoethyl ether; The good solvent includes at least one of N-N dimethylformamide, N-N dimethylacetamide, N-methylpyrrolidone or dimethyl sulfoxide; The coagulation bath comprises a good solvent and water, wherein the mass proportion of the good solvent is 10% to 70%; the temperature of the coagulation bath is 20 to 50°C.

2. The preparation method according to claim 1, characterized in that: The casting solution also includes a hydrophilic additive.

3. The preparation method according to claim 2, characterized in that: The hydrophilic additive includes at least one of polyvinyl pyrrolidone, polyethylene glycol, chitosan, polyvinyl alcohol, dextran, lithium chloride or lithium perchlorate.

4. The preparation method according to claim 2, characterized in that: In the casting solution, the mass proportion of the hydrophilic additive is less than or equal to 4%.

5. The preparation method according to claim 1, characterized in that: Use a doctor blade to apply a liquid film on the carrier.

6. The preparation method according to claim 1, characterized in that: During the liquid film coating process, the ambient temperature is 20~25°C and the humidity is 40RH%~70RH%.

7. The preparation method according to claim 1, characterized in that: The liquid film is immersed in the coagulation bath for 1 to 10 minutes.

8. A polyethersulfone membrane with a highly asymmetric structure, characterized in that: The method is prepared by any one of claims 1 to 7.

9. The polyethersulfone membrane with a highly asymmetric structure according to claim 8, characterized in that: The polyethersulfone membrane comprises a selective separation layer and a porous support layer; The thickness of the selective separation layer is 200-500 nm; The thickness of the polyethersulfone membrane is 100-150 μm.

10. Use of the polyethersulfone membrane with a highly asymmetric structure as claimed in claim 8 or 9 in protein or virus filtration.

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