Polymer membrane modification method, modified polymer membrane and filtration device

Abstract

A method for modifying a polymer membrane comprises pre-wetting the polymer membrane with a cross-linker solution comprising a first cross-linker and a second cross-linker; irradiating the pre-wetted polymer membrane to induce a cross-linking reaction; and rinsing the polymer membrane after the cross-linking reaction and drying it to obtain a modified polymer membrane. The polymer membrane modification method of the present invention utilizes two cross-linking agents to modify the polymer membrane, forming a 3D network on the surface and bulk of the polymer membrane to obtain a modified polymer membrane. The modified polymer membrane of the present invention exhibits low protein adsorption, caustic stability, autoclave stability, and gamma sterilization stability, while retaining overall mechanical properties and meeting the foldability requirements for filter preparation.

Description

Technical Field

[0001] The invention belongs to the field of biopharmaceuticals, and in particular relates to a polymer membrane modification method, a modified polymer membrane and a filtering device. Background Art

[0002] Membrane-based filtration technology has become an effective solution for separating and purifying proteins in the life sciences due to its low-temperature processing characteristics, high separation efficiency, and cost-effectiveness. However, protein adsorption to filter membranes is a long-standing problem, resulting in not only reduced membrane flux but also increased operating costs and product yield losses. Furthermore, in addition to protein adsorption, membrane performance must also be robust to caustic, autoclave, and gamma sterilization, depending on the requirements of the filtration application. Furthermore, the membrane's mechanical properties must meet the folding requirements for filter manufacturing.

[0003] Existing technologies primarily improve membrane performance and reduce protein adsorption by cross-linking agents with monomers. A cross-linking agent is a compound with two or more reactive functional groups, including but not limited to vinyl (double bond), hydroxyl, amide, and amine groups. A monomer is a compound with a single functional group, including but not limited to vinyl (double bond), hydroxyl, amide, and amine groups.

[0004] To reduce protein adsorption, Hou et al. disclosed in U.S. Patent No. 4,921,654 a method for preparing modified microporous membranes with hydroxyl, thiol, carboxyl, or amino functional groups. The patent discloses a surface grafting process in which glycidyl methacrylate (GMA) is grafted onto a polymer and then reacted with 3-hydroxypropyl acrylate (HPA) to complete the modification. The patent does not use a crosslinking agent, does not mention the membrane's caustic stability, and does not evaluate the effects of gamma sterilization or autoclaving on protein adsorption.

[0005] Gsell, in U.S. Patent No. 4,906,374, discloses a method for radiation-induced surface modification of porous polyamide substrates. The patent discloses monomers containing at least one hydroxyl group but does not mention a crosslinking agent. The patent does not address the caustic stability of the membrane, nor does it assess the effects of gamma sterilization or autoclaving on protein adsorption.

[0006] In another U.S. patent, No. 4,964,989, Gsell proposed a lyophilic, porous polymer substrate with a polymer coating to impart a low affinity for materials containing amide groups. A similar process for modifying PVDF membranes was proposed in U.S. Patent No. 5,019,260. In both cases, the membranes were modified using monomers with multiple hydroxyl groups and a crosslinking agent, but no mention was made of the membrane's caustic stability, nor was the effect of gamma sterilization or autoclaving on protein adsorption evaluated.

[0007] Steuck, in U.S. Patent No. 4,944,879, discloses a method for surface modification of composite porous membranes using electron beam irradiation using a monomer and a crosslinker, or a monomer and a pre-coated intermediate polymer. The monomers claimed in the patent include hydroxyalkyl acrylates or methacrylates, acrylamide or methacrylamide, and polar or functionally substituted acrylates or methacrylates. The patent does not address the caustic stability of the membranes, nor does it evaluate the effects of gamma sterilization or autoclaving on protein adsorption.

[0008] Charkoudian et al. (US20030077435A1, EP1779922A1, U.S. Patent No. 7284668B2, U.S. Patent Application US2012 / 028630A1) first claimed a method for preparing clean, corrosion-resistant porous membranes with thermal stability on a biomolecule-resistant surface using a terpolymer system comprising two monomers and a crosslinker. Furthermore, one of the claimed monomers, diacetone acrylamide, does not possess strong corrosion stability and is listed in the Safety Data Sheet (SDS) as "incompatible with strong bases and strong oxidants."

[0009] Thom et al., in U.S. Patent Nos. 2011 / 0244215A1 and 9045602B2, disclose a method for preparing microporous membranes using oligomers without a crosslinker by electron beam crosslinking. The modified membranes exhibit low protein adsorption, but the electron beam dose used in the patents is very high (50 to 200 kGy, with a claimed range of 1 to 300 kGy). There is no mention of caustic stability and foldability evaluation, nor is there any mention of the effects of autoclaving or gamma sterilization on protein adsorption performance.

[0010] In summary, in the existing modification technology, only one cross-linking agent and one or more monomers are used. Due to the poor caustic stability of acrylic compounds, most modified membranes have poor caustic stability, which leads to a sharp decrease in membrane performance. After the membrane was immersed in a sodium hydroxide solution with a pH of 13 for only two hours, the water flux of the membrane decreased by 75%.

[0011] In view of this, it is necessary to provide a method for modifying a polymer membrane using two cross-linking agents so that the modified membrane has low protein adsorption and has caustic stability, high pressure sterilization stability and gamma sterilization stability, so as to obtain a high performance modified polymer membrane. Summary of the Invention

[0012] To overcome the shortcomings of the prior art, one object of the present invention is to provide a method for modifying a polymer membrane. Another object of the present invention is to provide a modified polymer membrane. A further object of the present invention is to provide a filtration device. To achieve the above objects, the present invention employs the following technical solutions:

[0013] One aspect of the present invention provides a method for modifying a polymer film, comprising the following steps:

[0014] pre-wetting the polymer membrane with a cross-linker solution, the cross-linker solution comprising a first cross-linker and a second cross-linker;

[0015] irradiating the pre-moistened polymer film to induce a cross-linking reaction between the first cross-linking agent and the second cross-linking agent on the polymer film; or inducing a cross-linking reaction between the first cross-linking agent, the second cross-linking agent, and the polymer film;

[0016] The polymer film after the cross-linking reaction is washed and dried to obtain a modified polymer film.

[0017] Preferably, the polymer film, the first cross-linking agent, and the second cross-linking agent generate free radicals respectively after irradiation, and cross-linking reactions occur between the free radicals, thereby forming a 3D cross-linked network on the surface and body of the polymer film.

[0018] Preferably, the first cross-linking agent and the second cross-linking agent respectively generate free radicals after irradiation, and cross-linking reactions occur between the free radicals, thereby forming a 3D cross-linked network on the surface and body of the polymer film.

[0019] Preferably, the first cross-linking agent is a hydrophilic organic compound containing two or more first active reactive groups.

[0020] Preferably, the first reactive group is a bisacrylamide group.

[0021] Preferably, the first reactive group is at least one of methylenebisacrylamide and ethylidenebisacrylamide.

[0022] Preferably, the second cross-linking agent is a hydrophilic organic compound containing two or more second active reactive groups.

[0023] Preferably, the second reactive group is an acrylate group.

[0024] Preferably, the second reactive group comprises at least two acrylate bonds.

[0025] Preferably, the concentration of the first cross-linking agent is 0.3-0.8 wt %, and the concentration of the second cross-linking agent is 1.0-3.0 wt %.

[0026] Preferably, the irradiating the pre-wetted polymer film is to irradiate the pre-wetted polymer film with at least one of electron beam, X-ray, ultraviolet, gamma ray, plasma and thermal energy.

[0027] Preferably, the dose of the electron beam is 10-50 kGy.

[0028] Preferably, the flushing uses an alcohol solution.

[0029] Preferably, after the rinsing is completed, the alcohol solution is exchanged with distilled water.

[0030] Preferably, when the polymer membrane is a hydrophobic membrane, the cross-linking agent solution further comprises a low molecular alcohol aqueous solution.

[0031] Preferably, the polymer membrane is a microporous membrane.

[0032] Preferably, the polymer membrane is prepared from a copolymer or mixture of one or more of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, cellulose nitrate, polypropylene, polyethylene, polyolefin polymer, polyamide, polyimide, acrylic polymer, and methacrylic polymer.

[0033] Preferably, the protein adsorption capacity of the modified polymer membrane is less than or equal to 55 μg / cm 2 .

[0034] Preferably, the modified polymer film has a wetting time of less than or equal to 5 seconds.

[0035] Preferably, the water flux and bubble point value of the modified polymer membrane vary by less than or equal to 20% compared with those of the polymer membrane.

[0036] Preferably, the modified polymer membrane is caustic stable.

[0037] Preferably, after the modified polymer membrane is sterilized with caustic soda, the wetting time is less than or equal to 5 seconds, the changes in water flux and bubble point are less than or equal to 20%, and the protein adsorption capacity is less than or equal to 55 μg / cm 2 .

[0038] Preferably, the modified polymer film is autoclave stable.

[0039] Preferably, after the modified polymer membrane is sterilized by high pressure, the wetting time is less than or equal to 5 seconds, the changes in water flux and bubble point value are less than or equal to 20%, and the protein adsorption capacity is less than or equal to 55 μg / cm 2 .

[0040] Preferably, after gamma sterilization, the modified polymer membrane has a wetting time of less than or equal to 5 seconds, a change in water flux and bubble point value of less than or equal to 20%, and a protein adsorption capacity of less than or equal to 55 μg / cm 2 .

[0041] Another aspect of the present invention provides a modified polymer membrane, which is obtained by modifying a polymer membrane using the aforementioned polymer membrane modification method.

[0042] Preferably, the polymer membrane is a microporous membrane.

[0043] Preferably, the polymer membrane is made of one or more copolymers or mixtures of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, cellulose nitrate, polypropylene, polyethylene, polyolefin polymer, polyamide, polyimide, acrylic polymer, methacrylic polymer.

[0044] Preferably, the protein adsorption capacity of the modified polymer membrane is less than or equal to 55 μg / cm 2 .

[0045] Preferably, the modified polymer film has a wetting time of less than or equal to 5 seconds.

[0046] Preferably, the water flux and bubble point value of the modified polymer membrane vary by less than or equal to 20% compared with those of the polymer membrane.

[0047] Preferably, the modified polymer membrane is caustic stable.

[0048] Preferably, after the modified polymer membrane is sterilized with caustic soda, the wetting time is less than or equal to 5 seconds, the changes in water flux and bubble point are less than or equal to 20%, and the protein adsorption capacity is less than or equal to 55 μg / cm 2 .

[0049] Preferably, the modified polymer film is autoclave stable.

[0050] Preferably, after the modified polymer membrane is sterilized by high pressure, the wetting time is less than or equal to 5 seconds, the changes in water flux and bubble point value are less than or equal to 20%, and the protein adsorption capacity is less than or equal to 55 μg / cm 2 .

[0051] Preferably, the modified polymer film is gamma sterilization stable.

[0052] Preferably, after gamma sterilization, the modified polymer membrane has a wetting time of less than or equal to 5 seconds, a change in water flux and bubble point value of less than or equal to 20%, and a protein adsorption capacity of less than or equal to 55 μg / cm 2 .

[0053] Preferably, the modified polymer membrane is used in a filtration device.

[0054] Another aspect of the present invention provides a filtering device, comprising a housing having a fluid inlet and a fluid outlet, wherein the modified polymer membrane as described above is disposed within the housing.

[0055] The polymer membrane modification method of the present invention utilizes two crosslinking agents to modify the polymer membrane, forming a 3D network on the surface and bulk of the polymer membrane to obtain a modified polymer membrane. The modified polymer membrane of the present invention exhibits low protein adsorption, caustic stability, autoclave stability, and gamma sterilization stability, while retaining overall mechanical properties and meeting the foldability requirements for filter fabrication. The polymer membrane modification method and modified polymer membrane of the present invention possess high practical value and beneficial effects. DETAILED DESCRIPTION

[0056] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0057] The polymer membrane of the present invention is prepared from one or more copolymers or mixtures of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, cellulose nitrate, polypropylene, polyethylene, polyolefin polymer, polyamide, polyimide, acrylic polymer, methacrylic polymer.

[0058] The modification method of the polymer film of the present invention is:

[0059] pre-wetting the polymer membrane with a cross-linker solution, the cross-linker solution comprising a first cross-linker and a second cross-linker;

[0060] irradiating the pre-moistened polymer film to induce a cross-linking reaction between the first cross-linking agent and the second cross-linking agent on the polymer film or to induce a cross-linking reaction between the first cross-linking agent, the second cross-linking agent, and the polymer film;

[0061] The polymer film after the cross-linking reaction is washed and dried to obtain a modified polymer film.

[0062] When the polymer membrane is a hydrophilic membrane, the crosslinker solution includes the first crosslinker and the second crosslinker. Specifically, the first crosslinker and the second crosslinker are dissolved in an aqueous solution to obtain the crosslinker solution. When the polymer membrane is a hydrophobic membrane, the crosslinker solution includes the first crosslinker, the second crosslinker and a low-molecular alcohol aqueous solution. Specifically, the first crosslinker and the second crosslinker are dissolved in the low-molecular alcohol aqueous solution to obtain the crosslinker solution. The function of the low-molecular alcohol aqueous solution is to help the hydrophobic membrane to be wetted.

[0063] After the pre-wetted polymer film is irradiated, some polymer membranes will participate in the cross-linking reaction (such as PVDF or nylon membrane), that is, a cross-linking reaction will be initiated between the first cross-linker, the second cross-linker, and the polymer membrane. Specifically, the polymer membrane, the first cross-linker, and the second cross-linker will generate free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby forming a 3D cross-linked network on the surface and body of the polymer membrane; some polymer membranes will not participate in the cross-linking reaction (such as PES membrane will not participate in the reaction at room temperature and low dose), that is, the first cross-linker and the second cross-linker will be triggered to undergo a cross-linking reaction on the polymer membrane. Specifically, the first cross-linker and the second cross-linker will generate free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby forming a 3D cross-linked network on the surface and body of the polymer membrane.

[0064] To ensure the hydrophilicity of the modified polymer membrane, the first and second crosslinking agents can be hydrophilic organic compounds. For ease of comparison, the polymer membranes described in the Examples and Reference Examples utilize polyethersulfone (PES) membranes. PES membranes are hydrophobic and do not participate in the crosslinking reaction at room temperature and low doses. When using a hydrophilic polymer membrane or a polymer membrane that participates in the crosslinking reaction for modification, the crosslinker solution configuration and the crosslinking reaction differ as described above, but the experimental results are similar.

[0065] The polyethersulfone membrane (PES) is a hydrophobic polyethersulfone membrane (PES) made in the laboratory using the formula disclosed in the reference patent application US2023 / 0017950A1. The coating solution of the hydrophobic polyethersulfone membrane (PES) consists of 15-20wt% of PES resin, N-methyl-2-pyrrolidone (NMP) as a solvent, and triethylene glycol (TEG) as a non-solvent. The initial film formation occurs on a heated glass plate, and the formed film is then exposed to air with appropriate humidity, and finally immersed in a forming bath mainly composed of water, and the final solvent-non-solvent exchange extraction and the final shaping of the membrane are performed to obtain a polymer film. The polymer membrane is a microporous membrane, and the polymer membrane is a polyethersulfone membrane. After drying, the polymer membrane was moistened with 99.5% or greater isopropyl alcohol (IPA) and tested using a pore size analyzer (Innova CFP-200A). The membrane sample had a bubble point pressure of 15 to 30 psi and an average thickness of 130 ± 20 μm. The polymer membranes were modified in the Examples and Comparative Examples of the present invention. The modified polymer membranes were then subjected to water flux tests, bubble point tests, protein adsorption tests, and stability tests for caustic disinfection, autoclaving, and gamma sterilization, among others, to test the performance of the modified polymer membranes.

[0066] The present invention utilizes at least one of electron beams, X-rays, ultraviolet rays, gamma rays, plasma, and thermal energy to irradiate the pre-moistened polymer film, thereby modifying the polymer film. For ease of comparison, both the examples and the control examples utilize electron beams to modify the polymer film, with the electron beam dose ranging from 10 to 50 kGy. Specifically, both the examples and the control examples utilize 30 kGy electron beams to irradiate the polymer film. Similar experimental results were observed when the polymer film was irradiated with other electron beam doses. The specific steps are as follows:

[0067] The polymer film is cut into pieces approximately no less than 7 inches by 7 inches in size and then stored in 2 mil polyethylene (PE) bags. The polymer film is pre-wetted with a crosslinker solution, the crosslinker solution comprising a first crosslinker, a second crosslinker, and a low-molecular-weight alcohol aqueous solution. Specifically, the crosslinker solution is prepared by dissolving a specified amount of the first crosslinker and the second crosslinker in a 10 wt % low-molecular-weight alcohol aqueous solution. Specifically, the low-molecular-weight alcohol aqueous solution is IPA, which is used to help wet the hydrophobic polymer film. Specifically, the first crosslinker is a hydrophilic organic compound containing two or more first reactive groups. Specifically, the first reactive group is a bisacrylamide group, such as methylene bisacrylamide, ethylidene bisacrylamide, etc. The second crosslinker is a hydrophilic organic compound containing two or more second reactive groups. The second reactive group is an acrylate group. Specifically, the second crosslinker comprises at least two acrylate bonds, and ethoxylated trimethylolpropane triacrylate or propoxylated trimethylolpropane triacrylate compounds can be selected. After the polymer film is completely impregnated with the cross-linking agent solution, excess cross-linking agent solution on the polymer film is removed by a rubber roller.

[0068] The pre-wetted polymer film is irradiated with an electron beam to initiate a cross-linking reaction, forming a 3D network on the surface and bulk of the polymer film. Specifically, the polymer film is exposed to an electron beam at a certain accelerating voltage and dose at a line speed of 15 to 30 feet per minute under nitrogen. The first and second cross-linking agents are irradiated to generate free radicals. The cross-linking reaction can occur between the same or different free radicals, thereby forming a 3D cross-linked network on the surface and bulk of the polymer film.

[0069] The polymer film after electron beam irradiation was taken out from the PE bag and rinsed with IPA (isopropyl alcohol). After the rinsing was completed, the IPA was replaced with pure water, and the rinsed polymer film was then air-dried overnight to obtain a modified polymer film.

[0070] The modified polymer film was subjected to a performance test, and the test method was as follows:

[0071] 1. Performance test of modified polymer membrane

[0072] The performance tests of the modified polymer membrane include wetting time, water flux, bubble point, protein adsorption, etc. Specifically, the modified polymer membrane is first rinsed in IPA, then thoroughly rinsed in deionized water, and finally air-dried overnight. The performance of the polymer membrane is tested as follows:

[0073] 1. Wetting time

[0074] The wetting time is determined using the test method described in patent application US2023 / 0017950A1, which comprises placing a droplet (30 to 60 μL) of a 10% NaCl aqueous solution on the surface of the modified polymer film and recording the time (in seconds) required for the modified polymer film to be wetting. Specifically, the liquid can pass through the modified polymer film through the wetted portion of the modified polymer film, and the wetted portion of the modified polymer film is transparent compared to the non-wetted portion. The time required for the wetted portion of the surface of the modified polymer film to become transparent is recorded. It is generally believed that a wetting time of less than or equal to 5 seconds represents immediate wetting of the film.

[0075] 2. Water flux

[0076] The modified polymer membrane was cut into 47 mm discs, moistened with water and placed on a filter holder. The filter holder was connected to a pressurized water tank. Water passed through the modified polymer membrane under a pressure difference of 14.5 pounds per square inch. After reaching equilibrium, the water flux through the modified polymer membrane was measured in liters per square meter per hour per (pounds per square inch), i.e., LMH / psi.

[0077] 3. Bubble point test

[0078] The modified polymer membrane was cut into 47 mm discs, IPA was used as a wetting agent, and a bubble point test was performed using an pore size analyzer (Innova CFP-200A) according to ASTM F316. The bubble point test can measure the pore size of the modified polymer membrane, and the bubble point value is inversely proportional to the pore size.

[0079] 4. Protein adsorption test (reference patent EP 3586948 A1)

[0080] The protein adsorption of the modified polymer film was measured by a static immersion test using IgG protein. A protein solution was prepared using a model protein IgG (human IgG, ≥99%, Sigma-Aldrich Co.) in phosphate buffered saline (PBS, SigmaAldrich Co., LLC) at pH 7.4, with a concentration of 1 mg / ml. The modified polymer film was cut into multiple 13 mm discs (at least three per membrane group). One disc sample was placed in a 5 ml PTFE test tube and 2 ml of the protein solution was added using a calibrated micropipette. Three test tubes without disc samples were taken as negative controls. All test tubes were placed on a rotary vibrator stand at ambient temperature for two hours at a speed of 20 rpm, and then the test tubes were transferred to a clean UV cuvette and absorbance was measured at 280 nm using a UV spectrometer (ThermoFisher, Evolution One). A calibration curve was constructed using 0.25 mg / ml, 0.5 mg / ml, 0.75 mg / ml, and 1.0 mg / ml IgG solutions to determine the amount of IgG adsorbed on the surface. Based on the calibration curve, the amount of protein adsorbed on each disc was calculated using the following formula:

[0081] Protein adsorption capacity (μg / cm 2 ) = absorbance 样品 / Absorbance 阴性对照 *IgG solution concentration*Protein solution volume / membrane

[0082] area

[0083] 2. Performance testing of modified polymer membranes after disinfection or sterilization

[0084] After modifying the polymer film by electron beam irradiation, the modified polymer film is disinfected or sterilized, specifically comprising:

[0085] 1. Caustic alkali disinfection: Soak in 1N (equivalent concentration) sodium hydroxide (NaOH, pH = 14) aqueous solution at ambient temperature for ≥ 72 hours;

[0086] 2. Autoclave: Autoclave at 126°C for 1 hour;

[0087] 3. Gamma sterilization: Sterilization is carried out using gamma radiation with a dose of not less than 45kGy.

[0088] The aforementioned test methods were used to perform performance tests on the modified polymer membrane after caustic sterilization, high pressure sterilization, and gamma sterilization, including wetting time, water flux, bubble point value, protein adsorption, etc.

[0089] Comparative Example 1:

[0090] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.1 wt% MBAM and 3 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0091] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby forming a 3D cross-linked network on the surface and body of the polymer film.

[0092] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0093] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The film samples were numbered as Control Example 1.1 and Control Example 1.3.

[0094] Comparative Example 2:

[0095] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.1 wt% MBAM and 4 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0096] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0097] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0098] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Control Example 2.1 and Control Example 2.3.

[0099] Comparative Example 3:

[0100] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.2 wt% MBAM and 3.5 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0101] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0102] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0103] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Control Example 3.1 and Control Example 3.3.

[0104] Example 1:

[0105] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.3 wt% MBAM and 1 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0106] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0107] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0108] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Example 1.1, Example 1.5, and Example 1.6.

[0109] Example 2:

[0110] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.3 wt% MBAM and 2 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0111] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0112] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0113] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Example 2.1, Example 2.2, Example 2.5, and Example 2.6.

[0114] Example 3:

[0115] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.3 wt% MBAM and 3 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0116] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0117] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0118] The modified polymer film was cut into specific sizes to obtain modified film samples for testing, and the film samples were numbered as Example 3.1.

[0119] Example 4:

[0120] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and an aqueous low-molecular-weight alcohol solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous low-molecular-weight alcohol solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.4 wt% MBAM and 1 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0121] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0122] The polymer film after the cross-linking reaction is rinsed and dried to obtain a modified polymer film. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer film.

[0123] The modified polymer film was cut into specific sizes to obtain modified film samples for testing, and the modified film samples were numbered as Example 4.1.

[0124] Example 5:

[0125] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.4 wt% MBAM and 2 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0126] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0127] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0128] The modified polymer film was cut into specific sizes to obtain modified film samples for testing, and the modified film samples were numbered as Example 5.1.

[0129] Example 6:

[0130] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.4 wt% MBAM and 3 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0131] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0132] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0133] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Example 6.1, Example 6.2, Example 6.3, Example 6.4, and Example 6.7.

[0134] Example 7:

[0135] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.6 wt% MBAM and 1 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0136] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0137] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0138] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Example 7.1, Example 7.3, and Example 7.4.

[0139] Example 8:

[0140] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.6 wt% MBAM and 2 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0141] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0142] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0143] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Example 8.1, Example 8.3, and Example 8.4.

[0144] Example 9:

[0145] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.6 wt% MBAM and 3 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0146] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0147] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0148] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Example 9.1 and Example 9.7.

[0149] Example 10:

[0150] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.8 wt% MBAM and 1 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0151] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0152] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0153] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Example 10.1 and Example 10.7.

[0154] Example 11:

[0155] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.8 wt% MBAM and 2 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0156] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0157] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0158] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Example 11.1.

[0159] Example 12:

[0160] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.8 wt% MBAM and 3 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0161] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0162] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0163] The modified poly film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Example 12.1, Example 12.3, Example 12.4, Example 12.5, and Example 12.7.

[0164] Comparative Example 4:

[0165] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.8 wt% MBAM and 4 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0166] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0167] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0168] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Control Example 4.1, Control Example 4.2, Control Example 4.3, and Control Example 4.4.

[0169] Comparative Example 5:

[0170] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and a low-molecular-weight alcohol aqueous solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 0.8 wt% MBAM and 6 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0171] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0172] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0173] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Control Example 5.1, Control Example 5.3, and Control Example 5.4.

[0174] Comparative Example 6:

[0175] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), a second crosslinker, and an aqueous low-molecular-weight alcohol solution. The first crosslinker is N,N-methylenebisacrylamide (MBAM), the second crosslinker is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous low-molecular-weight alcohol solution is isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 1.2 wt% MBAM and 9 wt% ETMPTA in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution on the polymer film is removed using a rubber roller.

[0176] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction between the first cross-linker and the second cross-linker on the polymer film; specifically, the first cross-linker and the second cross-linker respectively generate their own free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0177] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0178] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Control Example 6.1 and Control Example 6.2.

[0179] Comparative Example 7:

[0180] The polymer film is pre-moistened with a crosslinker solution comprising a first crosslinker, N,N-methylenebisacrylamide (MBAM), and an aqueous low-molecular-weight alcohol solution, isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 1.2 wt% MBAM in 10 wt% IPA. After the polymer film is completely impregnated with the crosslinker solution, excess crosslinker solution is removed from the polymer film using a rubber roller.

[0181] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction of the first cross-linker on the polymer film; specifically, the first cross-linker generates free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0182] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0183] The modified polymer film was cut into specific sizes to obtain a modified film sample for testing, and the modified film sample was numbered as Control Example 7.1.

[0184] Comparative Example 8:

[0185] The polymer membrane is pre-moistened with a crosslinker solution comprising a second crosslinker, ethoxylated trimethylolpropane triacrylate (ETMPTA), and an aqueous low-molecular-weight alcohol solution, isopropyl alcohol (IPA). Specifically, the crosslinker solution is prepared by dissolving 4 wt% ETMPTA in 10 wt% IPA. After the polymer membrane is completely impregnated with the crosslinker solution, excess crosslinker solution is removed from the polymer membrane using a rubber roller.

[0186] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to induce a cross-linking reaction of the second cross-linker on the polymer film; specifically, the second cross-linker generates free radicals after irradiation, and the cross-linking reaction can be carried out between the same or different free radicals, thereby generating a 3D cross-linked network on the surface and body of the polymer film.

[0187] The polymer membrane after the cross-linking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After the rinsing is completed, the alcohol solution is replaced with distilled water to obtain a modified polymer membrane.

[0188] The modified polymer film was cut into specific sizes to obtain modified film samples for testing. The modified film samples were numbered as Control Example 8.1 and Control Example 8.3.

[0189] Example 13:

[0190] This example tests the wettability of the modified membrane samples described in Examples 1-12 and Comparative Examples 1-8 to study the effects of different ratios of the first crosslinking agent to the second crosslinking agent on the wettability of the modified membrane samples. The test results are shown in Table 1.

[0191] Table 1

[0192]

[0193] According to the test results in Table 1, the wetting time of Examples 1.1-12.1 and Comparative Examples 1.1-8.1 is less than 5 seconds, and all can achieve instant wetting.

[0194] Example 14:

[0195] This example tests the water flux and bubble point values ​​of the modified membrane samples described in Example 2, Example 6, Comparative Example 4, and Comparative Example 6. The test results are shown in Table 2.

[0196] Table 2

[0197]

[0198] According to the test results in Table 2, using lower concentrations of the first and second crosslinkers (Examples 2.2 and 6.2) had no significant effect on the water flux and bubble point of the polymer membranes before and after modification. However, using higher concentrations of the first and second crosslinkers (Comparative Examples 4.2 and 6.2) blocked some of the membrane pores, significantly reducing the water flux.

[0199] Example 15:

[0200] This example tested the caustic stability of the modified membrane samples described in Examples 6, 7, 8, and 12, as well as Comparative Examples 1-5 and 8. Specifically, the wetting time and water flux of the modified membrane samples after caustic disinfection were compared with the wetting time and water flux before disinfection. If the wetting time of the modified membrane samples after disinfection was still less than 5 seconds and the water flux changed by less than 20%, the modified polymer membrane was caustic-stable. Specifically, the caustic disinfection steps included soaking the modified membrane samples in a 1N NaOH solution for more than 72 hours, thoroughly rinsing the modified membrane samples with distilled water, and air-drying them overnight. Prior to testing, the modified membrane samples were baked in a 135°C oven for 2 hours. The test results for the wetting time of the modified membrane samples are shown in Table 3, and the test results for the water flux are shown in Table 4.

[0201] Table 3

[0202]

[0203] Table 4

[0204]

[0205] According to the test results in Table 3, the modified membrane samples treated with low concentrations or no MBAM (Control Examples 1.3-3.3, Control Example 8.3) showed a significant decrease in wettability after NaOH immersion. In contrast, Examples 6.3-8.3 and Example 12.3 maintained wettability after caustic disinfection.

[0206] In the prior art, as described by Charkoudian in US7648034, when After only two hours of immersion in a sodium hydroxide solution at pH 13, the membrane's water flux decreased by 75%. However, according to the test results in Table 4, the water flux of Examples 6.4-8.4, Example 12.4, and Control Examples 4.4-5.4 did not change significantly after caustic disinfection, demonstrating the importance of MBAM in the modification and highlighting the importance of MBAM concentration in ensuring caustic stability of the modified membrane samples in the harsh environment of high pH levels (pH 14).

[0207] In summary, the test results of this example show that the concentration of MBAM needs to be greater than 0.2 wt % to ensure the caustic stability of the modified membrane sample.

[0208] Example 16:

[0209] This example tested the autoclave stability of the modified membrane samples described in Examples 1, 2, and 12. Specifically, before testing, the wet modified membrane samples were air-dried and then oven-dried at 100°C for 2 hours. The wetting time, water flux, and bubble point of the modified membrane samples after autoclaving were compared with those before autoclaving. If, after sterilization, the wetting time of the modified membrane sample remained less than 5 seconds, the water flux changed by less than 20%, and the bubble point changed by less than 20%, the modified membrane sample was considered autoclave-stable. The test results are shown in Table 5.

[0210] Table 5

[0211]

[0212] According to the test results in Table 5, compared with the modified membrane sample before autoclaving, the wetting time, water flux and bubble point value of the modified membrane sample after autoclaving did not change significantly, that is, the modified membrane sample has autoclave stability.

[0213] Example 17:

[0214] This example tested the gamma sterilization stability of the modified membrane samples described in Examples 1 and 2. Specifically, the modified membrane samples were gamma-irradiated with ≥45 kGy of gamma radiation for gamma sterilization. Specifically, before testing, the wet modified membrane samples were air-dried and then oven-dried at 100°C for 2 hours. The wetting time, water flux, and bubble point of the modified membrane samples after gamma sterilization were compared with those before sterilization. If, after sterilization, the wetting time of the modified membrane samples remained less than 5 seconds, the water flux changed by less than 20%, and the bubble point changed by less than 20%, the modified polymer membrane was considered gamma-sterilization stable. The test results are shown in Table 6.

[0215] Table 6

[0216]

[0217] According to the test results in Table 6, the modified membrane samples were exposed to gamma rays with a dose of 49 kGy for sterilization. Compared with the modified membrane samples before gamma sterilization, the wetting time, water flux, and bubble point value of the modified membrane samples after gamma sterilization did not change significantly, that is, the modified membrane samples had gamma sterilization stability.

[0218] Example 18:

[0219] This example tested the protein adsorption of the modified membrane samples described in Examples 10, 12, 6, and 9. Three modified membrane samples from each group were sterilized and tested. After sterilization, the modified membrane samples were rinsed with IPA, then thoroughly rinsed with DI water, and air-dried overnight before testing.

[0220] In this example, the modified membrane sample was immersed in a 1N NaOH aqueous solution (pH = 14) for more than 72 hours for caustic disinfection; the modified membrane sample was autoclaved at 126 ° C for 1 hour for high pressure sterilization; the modified membrane sample was gamma sterilized at a dose greater than or equal to 45 kGy.

[0221] In this example, for the convenience of comparison, a commercially available The protein adsorption capacity of PVDF membrane and unmodified hydrophobic PES membrane was used as reference. The average protein adsorption capacity of PVDF membrane was 36.0±10.2μg / cm 2 The average protein adsorption capacity of the unmodified hydrophobic PES membrane was 140.6 ± 11.8 μg / cm 2 The test results are shown in Table 7.

[0222] Table 7

[0223]

[0224] The test results in Table 7 show that:

[0225] (1) Modified membrane samples and The membranes had similar protein adsorption amounts and were significantly lower than those of the unmodified hydrophobic membranes, indicating that protein adsorption was effectively reduced by modification.

[0226] (2) After caustic disinfection, high pressure sterilization, and gamma sterilization, the protein adsorption performance of the modified membrane sample did not change significantly, indicating that the modified membrane sample has caustic stability, high pressure sterilization stability, and gamma sterilization stability for protein adsorption.

[0227] (3) Although the modified membrane samples The membrane has similar protein adsorption capacity, but as described by Charkoudian in US7648034, when After the membrane was immersed in a sodium hydroxide solution with a pH of 13 for only two hours, the water flux of the membrane decreased by 75%. The membrane does not have caustic stability, but according to the test results of Example 15, the modified membrane sample described in this example has caustic stability. Therefore, the performance of the modified membrane sample described in this example is better than membrane.

[0228] Example 19:

[0229] This embodiment provides a use of the modified polymer membrane described in any one of Examples 1 to 12. In this embodiment, the modified polymer membrane is used in a filtration device, including a stacked filter, a cartridge filter, a capsule filter, or a spiral-wound filter.

[0230] The modified polymer membrane may be a flat sheet membrane or a hollow fiber membrane.

[0231] Example 20:

[0232] This embodiment provides a filtration device comprising a housing having a fluid inlet and a fluid outlet, wherein the modified polymer membrane as described in any one of embodiments 1 to 12 is disposed within the housing.

[0233] In this embodiment, the filtering device includes a stacked filter, a cartridge filter, a capsule filter, a spiral wound filter, etc.

[0234] The modified polymer membrane may be a flat sheet membrane or a hollow fiber membrane.

[0235] The polymer membrane modification method of the present invention utilizes two crosslinking agents to modify the polymer membrane, forming a 3D network on the surface and bulk of the polymer membrane to obtain a modified polymer membrane. The modified polymer membrane of the present invention exhibits low protein adsorption, caustic stability, autoclave stability, and gamma sterilization stability, while retaining overall mechanical properties and meeting the foldability requirements for filter fabrication. The polymer membrane modification method and modified polymer membrane of the present invention possess high practical value and beneficial effects.

[0236] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. A person skilled in the art will be able to make other variations or modifications based on the above description. The embodiments of the present invention are not exhaustive of all implementation methods. Any obvious variations or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention. All documents mentioned in the present invention are cited as references in this application, just as if each document were cited as a reference individually.

Claims

1. A method for modifying a polymer film, comprising the following steps: pre-wetting the polymer membrane with a cross-linker solution, the cross-linker solution comprising a first cross-linker and a second cross-linker; irradiating the pre-moistened polymer film to induce a cross-linking reaction between the first cross-linking agent and the second cross-linking agent on the polymer film; or inducing a cross-linking reaction between the first cross-linking agent, the second cross-linking agent, and the polymer film; washing the polymer film after the cross-linking reaction and drying it to obtain a modified polymer film; The first cross-linking agent is a hydrophilic organic compound containing two or more first reactive groups, and the first reactive groups are bisacrylamide groups; The second cross-linking agent is a hydrophilic organic compound containing two or more second active reactive groups, and the second active reactive groups are acrylate groups.

2. The method for modifying a polymer film according to claim 1, wherein: The polymer film, the first cross-linking agent, and the second cross-linking agent generate free radicals respectively after irradiation, and a cross-linking reaction occurs between the free radicals, thereby forming a 3D cross-linking network on the surface and body of the polymer film.

3. The method for modifying a polymer film according to claim 1, wherein: The first cross-linking agent and the second cross-linking agent respectively generate free radicals after irradiation, and cross-linking reactions occur between the free radicals, thereby forming a 3D cross-linked network on the surface and body of the polymer film.

4. The method for modifying a polymer film according to claim 1, wherein: The first active reaction group is at least one of methylene bisacrylamide and ethylidene bisacrylamide.

5. The method for modifying a polymer film according to claim 1, wherein: The second reactive group includes at least two acrylate bonds.

6. The method for modifying a polymer film according to claim 1, wherein: The concentration of the first cross-linking agent is 0.3-0.8 wt %, and the concentration of the second cross-linking agent is 1.0-3.0 wt %.

7. The method for modifying a polymer film according to claim 1, wherein: The irradiating the pre-wetted polymer film is to irradiate the pre-wetted polymer film with at least one of electron beam, X-ray, ultraviolet, gamma ray, plasma, and thermal energy.

8. The method for modifying a polymer film according to claim 7, wherein: The dose of the electron beam is 10-50 kGy.

9. The method for modifying a polymer film according to claim 1, wherein: The flushing adopts an alcohol solution.

10. The method for modifying a polymer film according to claim 9, wherein: After the rinsing is completed, the alcohol solution is exchanged with distilled water.

11. The method for modifying a polymer film according to claim 1, wherein: When the polymer membrane is a hydrophobic membrane, the cross-linking agent solution further comprises a low molecular alcohol aqueous solution.

12. The method for modifying a polymer film according to claim 1, wherein: The polymer film is a microporous film.

13. The method for modifying a polymer film according to claim 12, wherein: The polymer membrane is prepared from one or more copolymers or mixtures of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, cellulose nitrate, polypropylene, polyethylene, polyolefin polymer, polyamide, polyimide, acrylic polymer, methacrylic polymer.

14. The method for modifying a polymer film according to claim 1, wherein: The protein adsorption capacity of the modified polymer membrane is less than or equal to 55 μg / cm 2 .

15. The method for modifying a polymer film according to claim 1, wherein: The modified polymer film has a wetting time of less than or equal to 5 seconds.

16. The method for modifying a polymer film according to claim 1, wherein: The water flux and bubble point value of the modified polymer membrane are both less than or equal to 20% compared with the polymer membrane.

17. The method for modifying a polymer film according to claim 1, wherein: The modified polymer membrane is caustic stable.

18. The method for modifying a polymer film according to claim 17, wherein: After the modified polymer membrane is sterilized with caustic soda, the wetting time is less than or equal to 5 seconds, the changes in water flux and bubble point value are less than or equal to 20%, and the protein adsorption capacity is less than or equal to 55 μg / cm 2 .

19. The method for modifying a polymer film according to claim 1, wherein: The modified polymer film is autoclave stable.

20. The method for modifying a polymer film according to claim 19, wherein: After the modified polymer membrane is sterilized by high pressure, the wetting time is less than or equal to 5 seconds, the changes in water flux and bubble point value are less than or equal to 20%, and the protein adsorption capacity is less than or equal to 55 μg / cm 2 .

21. The method for modifying a polymer film according to claim 1, wherein: The modified polymer film is gamma sterilization stable.

22. The method for modifying a polymer film according to claim 21, wherein: After gamma sterilization, the modified polymer membrane has a wetting time of less than or equal to 5 seconds, a change in water flux and bubble point value of less than or equal to 20%, and a protein adsorption capacity of less than or equal to 55 μg / cm 2 .

23. A modified polymer film, obtained by modifying a polymer film using the polymer film modification method according to any one of claims 1 to 11.

24. The modified polymer film of claim 23, wherein The polymer film is a microporous film.

25. The modified polymer film of claim 24, wherein The polymer membrane is prepared from one or more copolymers or mixtures of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, cellulose nitrate, polypropylene, polyethylene, polyolefin polymer, polyamide, polyimide, acrylic polymer, methacrylic polymer.

26. The modified polymer film of claim 23, wherein The protein adsorption capacity of the modified polymer membrane is less than or equal to 55 μg / cm 2 .

27. The modified polymer film of claim 23, wherein The modified polymer film has a wetting time of less than or equal to 5 seconds.

28. The modified polymer film of claim 23, wherein The water flux and bubble point value of the modified polymer membrane are both less than or equal to 20% compared with the polymer membrane.

29. The modified polymer film of claim 23, wherein The modified polymer membrane is caustic stable.

30. The modified polymer film of claim 29, wherein After the modified polymer membrane is sterilized with caustic soda, the wetting time is less than or equal to 5 seconds, the changes in water flux and bubble point value are less than or equal to 20%, and the protein adsorption capacity is less than or equal to 55 μg / cm 2 .

31. The modified polymer film of claim 23, wherein The modified polymer film is autoclave stable.

32. The modified polymer film of claim 31, wherein After the modified polymer membrane is sterilized by high pressure, the wetting time is less than or equal to 5 seconds, the changes in water flux and bubble point value are less than or equal to 20%, and the protein adsorption capacity is less than or equal to 55 μg / cm 2 .

33. The modified polymer film of claim 23, wherein: The modified polymer film is gamma sterilization stable.

34. The modified polymer film of claim 33, wherein After gamma sterilization, the modified polymer membrane has a wetting time of less than or equal to 5 seconds, a change in water flux and bubble point value of less than or equal to 20%, and a protein adsorption capacity of less than or equal to 55 μg / cm 2 .

35. The modified polymer film of claim 23, wherein The modified polymer membrane is applied to a filtration device.

36. A filtering device comprising a housing having a fluid inlet and a fluid outlet, wherein the modified polymer membrane according to claim 23 is disposed within the housing.

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