Method for modifying polymer membrane, modified polymer membrane, and filtering device

Abstract

A method for modifying a polymer membrane. The method comprises: pre-wetting a polymer membrane with a cross-linking agent solution, the cross-linking agent solution comprising a first cross-linking agent and a second cross-linking agent; irradiating the pre-wetted polymer membrane to initiate a cross-linking reaction; and washing the polymer membrane that has been subjected to the cross-linking reaction, and drying same to obtain a modified polymer membrane. In the method for modifying a polymer membrane in the present invention, two cross-linking agents are used to modify the polymer membrane, and a 3D network is formed on the surface and the bulk of the polymer membrane, thereby obtaining the modified polymer membrane. The modified polymer membrane in the present invention has low protein adsorption, stability towards caustic alkali, and stability during high-pressure sterilization and gamma sterilization; moreover, the overall mechanical performance is retained, making same capable of meeting the requirement of filter preparation for foldability.

Description

A method for modifying a polymer membrane, the modified polymer membrane, and a filtration device. Technical Field

[0001] This invention belongs to the field of biopharmaceuticals, specifically relating to a method for modifying a polymer membrane, a modified polymer membrane, and a filtration device. Background Technology

[0002] Membrane-based filtration technology has become one of the effective solutions for separating and purifying proteins in life sciences due to its low-temperature processing characteristics, high separation efficiency, and cost-effectiveness. However, protein adsorption onto filter membranes has been a long-standing problem, leading not only to reduced membrane flux but also to increased operating costs and product yield losses. Furthermore, in addition to protein adsorption, the performance of filter membranes must meet the requirements of the filtration application, exhibiting stability against caustic alkalis, autoclaving, and gamma sterilization. Moreover, the mechanical properties of the filter membrane must also meet the pleating requirements for filter manufacturing.

[0003] Existing technologies primarily improve filter membrane performance by cross-linking the cross-linking reaction between cross-linking agents and monomers to reduce protein adsorption. Cross-linking agents are compounds with two or more reactive functional groups, including but not limited to vinyl (double bond), hydroxyl, amide, and amino groups. Monomers are compounds with a single functional group in their structure, including but not limited to vinyl (double bond), hydroxyl, amide, and amino groups.

[0004] To reduce protein adsorption, Hou et al. disclosed a method for preparing modified microporous membranes with hydroxyl, thiol, carboxyl, or amino functional groups in US Patent No. 4,921,654. This patent discloses a surface grafting process using glycidyl methacrylate (GMA) grafted onto a polymer, followed by a reaction with 3-hydroxypropyl acrylate (HPA) to complete the modification. This patent does not use a crosslinking agent. The patent does not mention the caustic alkali stability of the membrane, nor does it evaluate the effect of gamma sterilization or autoclaving on protein adsorption.

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

[0006] In another U.S. patent, No. 4,964,989, Gsell proposed a hydrophilic porous polymer substrate with a polymer coating to impart low affinity for materials containing amide groups. A similar process for modifying PVDF membranes is described in U.S. patent No. 5,019,260. In both cases, a monomer with multiple hydroxyl groups and a crosslinking agent are used to modify the membrane, but the caustic alkali stability of the membrane is not mentioned, nor is the effect of gamma sterilization or autoclaving on protein adsorption assessed.

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

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

[0009] Thom et al. disclosed a method for preparing microporous membranes using oligomers without crosslinking agents via electron beam crosslinking in U.S. Patents 2011 / 0244215A1 and 9045602B2. This modified membrane exhibits low protein adsorption, but the electron beam dose used in this patent is very high (50–200 kGy, with the claimed range being 1–300 kGy), and there is no mention of caustic alkali stability and foldability assessment, nor of the effect of autoclaving or gamma sterilization on protein adsorption performance.

[0010] In summary, existing modification technologies employ only one crosslinking agent and one or more monomers in their reaction. Due to the poor caustic and alkaline stability of acrylic compounds, most modified membranes exhibit poor caustic and alkaline stability, leading to a sharp decline in membrane performance. Charkoudian, in US7648034, mentions that when... After the membrane was immersed in a sodium hydroxide solution with pH=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 polymer membranes using two crosslinking agents to achieve low protein adsorption, as well as caustic alkali stability, autoclaving stability, and gamma sterilization stability, in order to obtain high-performance modified polymer membranes.

[0012] Summary of the Invention

[0013] To overcome the deficiencies of the prior art, one object of the present invention is to provide a method for modifying a polymer membrane; another object is to provide a modified polymer membrane; and yet another object is to provide a filtration device. To achieve the above objects, the technical solutions adopted by the present invention are as follows:

[0014] One aspect of the present invention provides a method for modifying a polymer film, comprising the following steps:

[0015] The polymer film is pre-wetted with a crosslinking agent solution, wherein the crosslinking agent solution comprises a first crosslinking agent and a second crosslinking agent;

[0016] Irradiation of the pre-wetted polymer film initiates a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film; or initiates a crosslinking reaction between the first crosslinking agent, the second crosslinking agent, and the polymer film.

[0017] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain the modified polymer membrane.

[0018] Optionally, the polymer film, the first crosslinking agent, and the second crosslinking agent are irradiated to generate free radicals, and crosslinking reactions occur between the free radicals, thereby forming a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0019] Optionally, the first crosslinking agent and the second crosslinking agent generate free radicals by irradiation, and the free radicals undergo a crosslinking reaction to form a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0020] Optionally, the first crosslinking agent is a hydrophilic organic compound containing two or more first active reactive groups.

[0021] Optionally, the first reactive group is a bisacrylamide group.

[0022] Optionally, the first active reactive group is at least one of methylenebisacrylamide and ethylbisacrylamide.

[0023] Optionally, the second crosslinking agent is a hydrophilic organic compound containing two or more second active reactive groups.

[0024] Optionally, the second reactive group is an acrylate group.

[0025] Optionally, the second reactive group comprises at least two acrylate bonds.

[0026] Optionally, the concentration of the first crosslinking agent is 0.3-0.8 wt%, and the concentration of the second crosslinking agent is 1.0-3.0 wt%.

[0027] Optionally, the irradiation of the pre-wetted polymer film can be performed by irradiating the pre-wetted polymer film with at least one of electron beam, X-ray, ultraviolet light, gamma rays, plasma, and thermal energy.

[0028] Optionally, the dose of the electron beam is 10-50 kGy.

[0029] Optionally, the rinsing is performed using an alcohol solution.

[0030] Optionally, after rinsing, the alcohol solution is replaced with distilled water.

[0031] Optionally, when the polymer membrane is a hydrophobic membrane, the crosslinking agent solution further includes a low-molecular-weight alcohol aqueous solution.

[0032] Optionally, the polymer membrane is a microporous membrane.

[0033] Optionally, the polymer membrane is prepared from one or more copolymers or mixtures of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, nitrocellulose, polypropylene, polyethylene, polyolefin polymers, polyamide, polyimide, acrylic polymers, and methacrylic polymers.

[0034] Optionally, the modified polymer membrane has a protein adsorption capacity of less than or equal to 55 μg / cm³. 2 .

[0035] Optionally, the wetting time of the modified polymer film is less than or equal to 5 seconds.

[0036] Optionally, the modified polymer membrane exhibits a change of less than or equal to 20% in both water flux and bubble point value compared to the original polymer membrane.

[0037] Optionally, the modified polymer film has caustic alkali stability.

[0038] Optionally, after sterilization with caustic alkali, the modified polymer membrane exhibits a wetting time of less than or equal to 5 seconds, a change in water flux and bubble point of less than or equal to 20%, and a protein adsorption capacity of less than or equal to 55 μg / cm³. 2 .

[0039] Optionally, the modified polymer film has high-pressure sterilization stability.

[0040] Optionally, after autoclaving, 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 / cm³. 2 .

[0041] Optionally, the modified polymer membrane has gamma sterilization stability.

[0042] Optionally, after gamma sterilization, the modified polymer membrane exhibits a wetting time of 5 seconds or less, a change in water flux and bubble point of 20% or less, and a protein adsorption capacity of 55 μg / cm³. 2 .

[0043] Another aspect of the present invention provides a modified polymer film, wherein the modified polymer film is obtained by modifying the polymer film using the polymer film modification method described above.

[0044] Optionally, the polymer membrane is a microporous membrane.

[0045] Optionally, the polymer membrane is prepared from one or more copolymers or mixtures of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, nitrocellulose, polypropylene, polyethylene, polyolefin polymers, polyamide, polyimide, acrylic polymers, and methacrylic polymers.

[0046] Optionally, the modified polymer membrane has a protein adsorption capacity of less than or equal to 55 μg / cm³. 2 .

[0047] Optionally, the wetting time of the modified polymer film is less than or equal to 5 seconds.

[0048] Optionally, the modified polymer membrane exhibits a change of less than or equal to 20% in both water flux and bubble point value compared to the original polymer membrane.

[0049] Optionally, the modified polymer film has caustic alkali stability.

[0050] Optionally, after sterilization with caustic alkali, the modified polymer membrane exhibits a wetting time of less than or equal to 5 seconds, a change in water flux and bubble point of less than or equal to 20%, and a protein adsorption capacity of less than or equal to 55 μg / cm³. 2 .

[0051] Optionally, the modified polymer film has high-pressure sterilization stability.

[0052] Optionally, after autoclaving, 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 / cm³. 2 .

[0053] Optionally, the modified polymer membrane has gamma sterilization stability.

[0054] Optionally, after gamma sterilization, the modified polymer membrane exhibits a wetting time of 5 seconds or less, a change in water flux and bubble point of 20% or less, and a protein adsorption capacity of 55 μg / cm³. 2 .

[0055] Optionally, the modified polymer membrane is used in a filtration device.

[0056] Another aspect of the present invention provides a filtration device including a housing having a fluid inlet and a fluid outlet, wherein the housing is provided with a modified polymer membrane as described above.

[0057] The polymer membrane modification method of this invention employs two crosslinking agents to modify the polymer membrane, forming a 3D network on the surface and bulk of the polymer membrane to obtain the modified polymer membrane. The modified polymer membrane of this invention exhibits low protein adsorption, caustic alkali stability, autoclaving stability, and gamma sterilization stability, while retaining its overall mechanical properties, meeting the foldability requirements for filter fabrication. The polymer membrane modification method and the modified polymer membrane of this invention have high practical value and beneficial effects. Detailed Implementation

[0058] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0059] The polymer membrane described in this invention is prepared from one or more copolymers or mixtures of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, nitrocellulose, polypropylene, polyethylene, polyolefin polymer, polyamide, polyimide, acrylic polymer, and methacrylic polymer.

[0060] The method for modifying the polymer film described in this invention is as follows:

[0061] The polymer film is pre-wetted with a crosslinking agent solution, wherein the crosslinking agent solution comprises a first crosslinking agent and a second crosslinking agent;

[0062] Irradiation of the pre-wetted polymer film can induce a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film, or induce a crosslinking reaction between the first crosslinking agent, the second crosslinking agent, and the polymer film.

[0063] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain the modified polymer membrane.

[0064] When the polymer membrane is a hydrophilic membrane, the crosslinking agent solution includes the first crosslinking agent and the second crosslinking agent. Specifically, the first crosslinking agent and the second crosslinking agent are dissolved in an aqueous solution to obtain the crosslinking agent solution. When the polymer membrane is a hydrophobic membrane, the crosslinking agent solution includes the first crosslinking agent, the second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. Specifically, the first crosslinking agent and the second crosslinking agent are dissolved in the low-molecular-weight alcohol aqueous solution to obtain the crosslinking agent solution. The role of the low-molecular-weight alcohol aqueous solution is to help wet the hydrophobic membrane.

[0065] After irradiation, some polymer films (such as PVDF or nylon films) will participate in crosslinking reactions, that is, initiating crosslinking reactions between the first crosslinking agent, the second crosslinking agent, and the polymer film. Specifically, the polymer film, the first crosslinking agent, and the second crosslinking agent generate free radicals after irradiation. The crosslinking reaction can occur between the same or different free radicals, thereby forming a 3D crosslinked network on the surface and bulk of the polymer film. Some polymer films will not participate in crosslinking reactions (such as PES films, which do not participate in the reaction at room temperature and low doses). That is, the first crosslinking agent and the second crosslinking agent will undergo crosslinking reactions on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate free radicals after irradiation. The crosslinking reaction can occur between the same or different free radicals, thereby forming a 3D crosslinked network on the surface and bulk of the polymer film.

[0066] To ensure the hydrophilicity of the modified polymer membrane, the first and second crosslinking agents can be selected from hydrophilic organic compounds. For ease of comparison, the polymer membranes described in the embodiments and comparative examples of the present invention are polyethersulfone (PES) membranes, which are hydrophobic membranes and do not participate in the crosslinking reaction at room temperature and low doses. When using hydrophilic polymer membranes or polymer membranes that participate in the crosslinking reaction for modification, the preparation of the crosslinking agent solution and the crosslinking reaction will differ as described above, but the experimental results will be similar.

[0067] The polyethersulfone (PES) membrane is a hydrophobic polyethersulfone (PES) membrane manufactured in the laboratory using the formulation disclosed in patent application US2023 / 0017950A1. The coating solution for the hydrophobic PES membrane consists of 15-20 wt% PES resin, N-methyl-2-pyrrolidone (NMP) as a solvent, and triethylene glycol (TEG) as a non-solvent. Initial membrane formation occurs on a heated glass plate, followed by exposure of the formed membrane to air with appropriate humidity, and finally immersion in a formation bath primarily composed of water for final solvent-non-solvent exchange extraction and final membrane shaping to obtain the polymer membrane. The polymer membrane is a microporous membrane, and the polymer membrane is a polyethersulfone membrane. After drying, the polymer membrane was wetted with isopropanol (IPA) of 99.5% or higher. The membrane sample was tested using a pore size analyzer (Innova CFP-200A), yielding a bubble point pressure of 15–30 psi and an average thickness of 130 ± 20 μm. In the embodiments and control examples of this invention, the polymer membrane was modified. The modified polymer membrane underwent water flux testing, bubble point testing, protein adsorption testing, and stability testing under caustic alkali sterilization, autoclaving, and gamma sterilization to assess its performance.

[0068] This invention modifies the pre-wetted polymer film by irradiating it with at least one of electron beams, X-rays, ultraviolet rays, gamma rays, plasma, or thermal energy. For ease of comparison, both the embodiments and control examples of this invention use electron beams to modify the polymer film, with a dose of 10-50 kGy. Specifically, both the embodiments and control examples use a 30 kGy electron beam to irradiate the polymer film. When other doses of electron beams are used, the experimental results are similar. The specific steps are as follows:

[0069] The polymer film is cut into fragments approximately 7 inches by 7 inches in size and then stored in 2-mil polyethylene (PE) bags. The polymer film is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. Specifically, the crosslinking agent solution is prepared by dissolving a specified amount of the first crosslinking agent and the second crosslinking agent in a 10 wt% low-molecular-weight alcohol aqueous solution, specifically, the low-molecular-weight alcohol aqueous solution being IPA, used to aid in wetting the hydrophobic polymer film. Specifically, the first crosslinking agent is a hydrophilic organic compound containing two or more first reactive groups, specifically, the first reactive group being a bisacrylamide group, such as methylenebisacrylamide, ethylbisacrylamide, etc. The second crosslinking agent is a hydrophilic organic compound containing two or more second reactive groups, the second reactive groups being acrylate groups. Specifically, the second crosslinking agent includes at least two acrylate bonds, and can be selected from ethoxylated trimethylolpropane triacrylate or propoxylated trimethylolpropane triacrylate compounds. After the polymer film is completely impregnated with the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed by a rubber roller.

[0070] A pre-wetted polymer membrane is irradiated with an electron beam to initiate a crosslinking reaction, forming a 3D network on the surface and bulk of the polymer membrane. Specifically, the polymer membrane is exposed to an electron beam at a linear velocity of 15–30 feet per minute under nitrogen atmosphere, with a specific accelerating voltage and dose. The first and second crosslinking agents generate free radicals upon irradiation, and the crosslinking reaction can occur between the same or different free radicals, thereby forming a 3D crosslinked network on the surface and bulk of the polymer membrane.

[0071] The polymer membrane, after being irradiated with an electron beam, was removed from the PE bag and rinsed with IPA (isopropanol). After rinsing, the IPA was replaced with pure water, and the rinsed polymer membrane was then air-dried overnight to obtain the modified polymer membrane.

[0072] The modified polymer film was subjected to performance testing, and the testing method is as follows:

[0073] I. Performance Testing of Modified Polymer Membranes

[0074] The performance tests of the modified polymer membrane include wetting time, water flux, bubble point, and protein adsorption. 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 then tested using the following method:

[0075] 1. Wetting time

[0076] The wetting time was determined using the test method described in patent application US2023 / 0017950A1. This method involves placing a droplet (30–60 μL) of a 10% NaCl aqueous solution on the surface of the modified polymer membrane and recording the time (in seconds) required for the modified polymer membrane to wet. Specifically, the liquid can pass through the wetted portion of the modified polymer membrane. Compared to the unwetted portion, the wetted portion of the modified polymer membrane is transparent. The time required for the wetted portion of the surface of the modified polymer membrane to become transparent is recorded. A wetting time of 5 seconds or less is generally considered to represent immediate wetting of the membrane.

[0077] 2. Water flux

[0078] The modified polymer membrane was cut into 47 mm discs, moistened with water, and placed on a filter holder. The filter holder was then connected to a pressurized water tank. Water was passed through the modified polymer membrane at a pressure differential of 14.5 psi. After reaching equilibrium, the water flux through the modified polymer membrane was measured in liters per square meter per hour per pound per square inch (LMH / psi).

[0079] 3. Bubble Point Test

[0080] The modified polymer film was cut into 47 mm discs, and IPA was used as a wetting agent. Bubble point tests were performed using a pore size analyzer (Innova CFP-200A) according to ASTM F316 standard. The bubble point test measures the pore size of the modified polymer film; the bubble point value is inversely proportional to the pore size.

[0081] 4. Protein adsorption test (refer to patent EP 3586948 A1)

[0082] Protein adsorption on the modified polymer membrane was measured using a static immersion assay with IgG protein. A protein solution of the model protein IgG (human IgG, ≥99%, Sigma-Aldrich Co.) was prepared in phosphate-buffered saline (PBS, pH 7.4, Sigma-Aldrich Co., LLC) at a concentration of 1 mg / ml. The modified polymer membrane was cut into multiple 13 mm discs (at least three per membrane group). One disc sample was placed in a 5 ml PTFE tube, and 2 ml of the protein solution was added using a calibrated micropipette. Three additional tubes without disc samples were used as negative controls. All tubes were placed on a vibratory stand at 20 rpm at ambient temperature for two hours, then transferred to clean UV cuvettes, and absorbance was measured at 280 nm using a Thermo Fisher Evolution One UV spectrometer. Calibration curves were constructed using IgG solutions at concentrations of 0.25 mg / ml, 0.5 mg / ml, 0.75 mg / ml, and 1.0 mg / ml to determine the amount of IgG adsorbed on the surface. Based on the calibration curves, the amount of protein adsorbed on each disc was calculated using the following formula:

[0083] Protein adsorption capacity (μg / cm) 2 ) = Absorbance 样品 Absorbance 阴性对照 *IgG solution concentration* Protein solution volume / membrane area

[0084] II. Performance Testing of Modified Polymer Membranes After Disinfection or Sterilization

[0085] After modifying the polymer film by electron beam irradiation, the modified polymer film is sterilized or disinfected, specifically including:

[0086] 1. Caustic alkali disinfection: Immerse in a 1N (equivalent concentration) sodium hydroxide (NaOH, pH=14) aqueous solution at ambient temperature for ≥72 hours;

[0087] 2. Autoclaving: Autoclave at 126℃ for 1 hour;

[0088] 3. Gamma sterilization: Sterilization is performed using gamma radiation with a dose of not less than 45 kGy.

[0089] The modified polymer membrane after caustic alkali sterilization, autoclaving, and gamma sterilization was subjected to performance tests using the aforementioned test methods, including wetting time, water flux, bubble point value, and protein adsorption.

[0090] Compare with Example 1:

[0091] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.1 wt% of MBAM and 3 wt% of ETMPTA in 10 wt% IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0092] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby forming a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0093] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0094] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing. The membrane samples were numbered as Control Example 1.1 and Control Example 1.3.

[0095] Compare with Example 2:

[0096] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.1 wt% of MBAM and 4 wt% of ETMPTA in 10 wt% IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0097] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0098] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0099] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing. The modified membrane samples were numbered as Control Example 2.1 and Control Example 2.3.

[0100] Compare with Example 3:

[0101] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.2 wt% of MBAM and 3.5 wt% of ETMPTA in 10 wt% IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0102] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0103] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0104] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing. The modified membrane samples were numbered as Control Example 3.1 and Control Example 3.3.

[0105] Example 1:

[0106] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.3 wt% of MBAM and 1 wt% of ETMPTA in 10 wt% of IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0107] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0108] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0109] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing. The modified membrane samples were numbered as Example 1.1, Example 1.5, and Example 1.6.

[0110] Example 2:

[0111] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.3 wt% of MBAM and 2 wt% of ETMPTA in 10 wt% of IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0112] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0113] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0114] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing. The modified membrane samples were numbered as Example 2.1, Example 2.2, Example 2.5, and Example 2.6.

[0115] Example 3:

[0116] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.3 wt% of MBAM and 3 wt% of ETMPTA in 10 wt% IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0117] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0118] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0119] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing, and the membrane samples were numbered Example 3.1.

[0120] Example 4:

[0121] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.4 wt% of MBAM and 1 wt% of ETMPTA in 10 wt% of IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0122] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0123] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0124] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing, and the modified membrane samples were numbered Example 4.1.

[0125] Example 5:

[0126] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.4 wt% of MBAM and 2 wt% of ETMPTA in 10 wt% IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0127] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0128] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0129] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing, and the modified membrane samples were numbered Example 5.1.

[0130] Example 6:

[0131] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.4 wt% of MBAM and 3 wt% of ETMPTA in 10 wt% IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0132] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0133] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0134] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing. The modified membrane samples were numbered as Example 6.1, Example 6.2, Example 6.3, Example 6.4, and Example 6.7.

[0135] Example 7:

[0136] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.6 wt% of MBAM and 1 wt% of ETMPTA in 10 wt% of IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0137] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0138] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0139] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing. The modified membrane samples were numbered as Example 7.1, Example 7.3, and Example 7.4.

[0140] Example 8:

[0141] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.6 wt% of MBAM and 2 wt% of ETMPTA in 10 wt% IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0142] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0143] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0144] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing. The modified membrane samples were numbered as Example 8.1, Example 8.3, and Example 8.4.

[0145] Example 9:

[0146] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.6 wt% of MBAM and 3 wt% of ETMPTA in 10 wt% IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0147] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0148] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0149] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing. The modified membrane samples were numbered as Example 9.1 and Example 9.7.

[0150] Example 10:

[0151] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.8 wt% of MBAM and 1 wt% of ETMPTA in 10 wt% of IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0152] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0153] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0154] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing. The modified membrane samples were numbered as Example 10.1 and Example 10.7.

[0155] Example 11:

[0156] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.8 wt% of MBAM and 2 wt% of ETMPTA in 10 wt% of IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0157] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0158] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0159] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing, and the modified membrane samples were numbered Example 11.1.

[0160] Example 12:

[0161] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.8 wt% of MBAM and 3 wt% of ETMPTA in 10 wt% of IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0162] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0163] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0164] The modified polyfilm was cut into specific sizes to obtain modified membrane samples for testing. The modified membrane samples were numbered as Example 12.1, Example 12.3, Example 12.4, Example 12.5, and Example 12.7.

[0165] Compare with Example 4:

[0166] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.8 wt% of MBAM and 4 wt% of ETMPTA in 10 wt% IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0167] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0168] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0169] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing. The modified membrane samples were numbered as Control Example 4.1, Control Example 4.2, Control Example 4.3, and Control Example 4.4.

[0170] Compare with Example 5:

[0171] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.8 wt% of MBAM and 6 wt% of ETMPTA in 10 wt% of IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0172] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0173] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0174] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing. The modified membrane samples were numbered as Control Example 5.1, Control Example 5.3, and Control Example 5.4.

[0175] Compare with Example 6:

[0176] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent, a second crosslinking agent, and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 1.2 wt% of MBAM and 9 wt% of ETMPTA in 10 wt% of IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0177] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film. Specifically, the first crosslinking agent and the second crosslinking agent generate their respective free radicals after irradiation. The crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0178] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0179] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing. The modified membrane samples were numbered as Control Example 6.1 and Control Example 6.2.

[0180] Compare with Example 7:

[0181] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a first crosslinking agent and a low-molecular-weight alcohol aqueous solution. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 1.2 wt% of MBAM in 10 wt% IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0182] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a crosslinking reaction of the first crosslinking agent on the polymer film. Specifically, the first crosslinking agent generates free radicals after irradiation, and the crosslinking reaction can be carried out between the same or different free radicals, thereby generating a 3D crosslinked network on the surface and in the bulk of the polymer film.

[0183] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0184] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing, and the modified membrane samples were numbered as Control Example 7.1.

[0185] Compare with Example 8:

[0186] The polymer membrane is pre-wetted with a crosslinking agent solution comprising a second crosslinking agent and a low-molecular-weight alcohol aqueous solution. The second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the low-molecular-weight alcohol aqueous solution is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 4 wt% ETMPTA in 10 wt% IPA. After completely impregnating the polymer membrane with the crosslinking agent solution, excess crosslinking agent solution is removed from the polymer membrane using a rubber roller.

[0187] The pre-wetted polymer film is irradiated with a 30 kGy electron beam to initiate a cross-linking reaction of the second cross-linking agent on the polymer film. Specifically, the second cross-linking agent 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 in the bulk of the polymer film.

[0188] The polymer membrane after the crosslinking reaction is rinsed and dried to obtain a modified polymer membrane. The rinsing is performed using an alcohol solution. After rinsing, the alcohol solution is replaced with distilled water to obtain the modified polymer membrane.

[0189] The modified polymer membrane was cut into specific sizes to obtain modified membrane samples for testing. The modified membrane samples were numbered as Control Example 8.1 and Control Example 8.3.

[0190] Example 13:

[0191] This embodiment tests the wettability of the modified membrane samples described in Examples 1-12 and Comparative Examples 1-8, and studies the effect of different ratios of the first crosslinking agent and the second crosslinking agent on the wettability of the modified membrane samples. The test results are shown in Table 1.

[0192] Table 1

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

[0194] Example 14:

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

[0196] Table 2

[0197] According to the test results in Table 2, using lower concentrations of the first and second crosslinking agents (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 crosslinking agents (Comparative Examples 4.2 and 6.2) blocked some of the membrane pores of the polymer membrane, thereby significantly reducing the water flux.

[0198] Example 15:

[0199] This embodiment tests the caustic alkali stability of the modified membrane samples described in Examples 6, 7, 8, 12 and Comparative Examples 1-5 and Comparative Example 8. Specifically, the wetting time and water flux of the modified membrane sample after caustic alkali sterilization are compared with those before caustic alkali sterilization. If the wetting time of the modified membrane sample after sterilization is still less than 5 seconds and the change in water flux is less than 20%, it indicates that the modified polymer membrane has caustic alkali stability. Specifically, the caustic alkali sterilization step is as follows: the modified membrane sample is soaked in 1N NaOH solution for more than 72 hours, the modified membrane sample is thoroughly rinsed with distilled water, and air-dried overnight. Before testing, the modified membrane sample is baked in an oven at 135°C for 2 hours. The test results of the wetting time of the modified membrane sample are shown in Table 3, and the test results of the water flux are shown in Table 4.

[0200] Table 3

[0201] Table 4

[0202] According to the test results in Table 3, the modified membrane samples obtained by treatment with low concentrations or no MBAM (Control Examples 1.3-3.3, Control Example 8.3) showed a significant decrease in wettability after immersion in NaOH. In contrast, the membrane samples of Examples 6.3-8.3 and Example 12.3 maintained wettability after sterilization with caustic alkali.

[0203] In the prior art, as described by Charkoudian in US7648034, when... After immersing the membrane in a sodium hydroxide solution at pH 13 for only two hours, 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 alkali sterilization, demonstrating the importance of MBAM in the modification and highlighting the importance of ensuring the caustic alkali stability of the modified membrane samples in the harsh environment of high pH levels (pH 14).

[0204] In summary, the test results of this embodiment show that the concentration of MBAM needs to be greater than 0.2 wt% to ensure the caustic alkali stability of the modified membrane sample.

[0205] Example 16:

[0206] This embodiment tests the autoclaving stability of the modified membrane samples described in Examples 1, 2, and 12. Specifically, before the test, the wet modified membrane samples were first air-dried, and then dried at 100°C for 2 hours. Specifically, the wetting time, water flux, and bubble point value of the modified membrane samples after autoclaving were compared with those before sterilization. If, after sterilization, the wetting time of the modified membrane samples is still less than 5 seconds, the change in water flux is less than 20%, and the change in bubble point value is less than 20%, then the modified membrane samples have autoclaving stability. The test results are shown in Table 5.

[0207] Table 5

[0208] 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, indicating that the modified membrane sample has autoclaving stability.

[0209] Example 17:

[0210] This embodiment tests the gamma sterilization stability of the modified membrane samples described in Examples 1 and 2. Specifically, the modified membrane samples were irradiated with ≥45 kGy for gamma sterilization. Before testing, the wet modified membrane samples were first air-dried, and then 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 is still less than 5 seconds, the change in water flux is less than 20%, and the change in bubble point is less than 20%, then the modified polymer membrane exhibits gamma sterilization stability. The test results are shown in Table 6.

[0211] Table 6

[0212] According to the test results in Table 6, the modified membrane sample was sterilized by exposing it to gamma rays at a dose of 49 kGy. Compared with the modified membrane sample before gamma sterilization, the wetting time, water flux, and bubble point value of the modified membrane sample after gamma sterilization did not change significantly, that is, the modified membrane sample has gamma sterilization stability.

[0213] Example 18:

[0214] This embodiment tests 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 accordingly, and each group of modified membrane samples was tested. After sterilization, the modified membrane samples were first rinsed with IPA, then thoroughly rinsed with DI water, and air-dried overnight before testing.

[0215] In this embodiment, the modified membrane sample was soaked in 1N NaOH aqueous solution (pH=14) for more than 72 hours for caustic alkali disinfection; the modified membrane sample was autoclaved at 126°C for 1 hour; and the modified membrane sample was gamma sterilized at a dose of ≥45kGy.

[0216] In this embodiment, for ease of comparison, a commercially available product known for its low protein adsorption performance was tested. Protein adsorption capacity of PVDF membrane and unmodified hydrophobic PES membrane was used as a reference. The average protein adsorption capacity of the PVDF membrane was 36.0 ± 10.2 μg / cm³. 2 The average protein adsorption capacity of the unmodified hydrophobic PES membrane was 140.6 ± 11.8 μg / cm³. 2 The test results are shown in Table 7.

[0217] Table 7

[0218] The test results in Table 7 show that:

[0219] (1) Modified membrane sample and The membrane exhibited similar protein adsorption capacity, but significantly lower than the unmodified hydrophobic membrane, indicating that the modification effectively reduced protein adsorption.

[0220] (2) After caustic alkali sterilization, autoclaving and gamma sterilization, the protein adsorption performance of the modified membrane sample did not change significantly, indicating that the modified membrane sample has caustic alkali stability, autoclaving stability and gamma sterilization stability for protein adsorption.

[0221] (3) Although the modified membrane sample and The membranes have similar protein adsorption capacities, but as Charkoudian describes in US7648034, when... After the membrane was immersed in a sodium hydroxide solution with pH=13 for only two hours, the membrane's water flux decreased by 75%, i.e. The membrane does not possess caustic alkali stability, while according to the test results of Example 15, the modified membrane sample described in this example does possess caustic alkali stability. Therefore, the performance of the modified membrane sample described in this example is superior. membrane.

[0222] Example 19:

[0223] This embodiment provides the use of the modified polymer membrane described in any of Examples 1 to 12. In this embodiment, the modified polymer membrane is used in a filtration device. The filtration device includes a stacked filter, a cartridge filter, a capsule filter, and a spiral wound filter.

[0224] The modified polymer membrane can be a flat sheet membrane or a hollow fiber membrane.

[0225] Example 20:

[0226] This embodiment provides a filtration device. The filtration device includes a housing having a fluid inlet and a fluid outlet, and the housing contains a modified polymer membrane as described in any of Examples 1 to 12.

[0227] In this embodiment, the filtration device includes stacked filters, cartridge filters, capsule filters, spiral wound filters, etc.

[0228] The modified polymer membrane can be a flat sheet membrane or a hollow fiber membrane.

[0229] The polymer membrane modification method of this invention employs two crosslinking agents to modify the polymer membrane, forming a 3D network on the surface and bulk of the polymer membrane to obtain the modified polymer membrane. The modified polymer membrane of this invention exhibits low protein adsorption, caustic alkali stability, autoclaving stability, and gamma sterilization stability, while retaining its overall mechanical properties, meeting the foldability requirements for filter fabrication. The polymer membrane modification method and the modified polymer membrane of this invention have high practical value and beneficial effects.

[0230] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. The embodiments exemplified by the present invention cannot exhaustively describe all implementation methods. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention. All documents mentioned in this invention are incorporated herein by reference as if a single document were independently incorporated by reference.

Claims

1. A method for modifying a polymer film, comprising the following steps: The polymer film is pre-wetted with a crosslinking agent solution, wherein the crosslinking agent solution comprises a first crosslinking agent and a second crosslinking agent; Irradiation of the pre-wetted polymer film initiates a crosslinking reaction between the first crosslinking agent and the second crosslinking agent on the polymer film; or initiates a crosslinking reaction between the first crosslinking agent, the second crosslinking agent, and the polymer film. The polymer membrane after the crosslinking reaction is rinsed and dried to obtain the modified polymer membrane.

2. The method for modifying the polymer film according to claim 1, wherein, The polymer film, the first crosslinking agent, and the second crosslinking agent are irradiated to generate free radicals, and crosslinking reactions occur between the free radicals, thereby forming a 3D crosslinked network on the surface and in the bulk of the polymer film.

3. The method for modifying the polymer film according to claim 1, wherein, The first crosslinking agent and the second crosslinking agent generate free radicals after irradiation, and the free radicals undergo crosslinking reactions to form a 3D crosslinked network on the surface and in the bulk of the polymer film.

4. The method for modifying the polymer film according to claim 1, wherein, The first crosslinking agent is a hydrophilic organic compound containing two or more first active reactive groups.

5. The method for modifying the polymer film according to claim 4, wherein, The first reactive group is a bisacrylamide group.

6. The method for modifying the polymer film according to claim 5, wherein, The first active reactive group is at least one of methylenebisacrylamide and ethylbisacrylamide.

7. The method for modifying the polymer film according to claim 1, wherein, The second crosslinking agent is a hydrophilic organic compound containing two or more second active reactive groups.

8. The method for modifying the polymer film according to claim 7, wherein, The second reactive group is an acrylate group.

9. The method for modifying the polymer film according to claim 8, wherein, The second reactive group comprises at least two acrylate bonds.

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

11. The method for modifying the polymer film according to claim 1, wherein, The irradiation of the pre-wetted polymer film is performed by irradiating the pre-wetted polymer film with at least one of electron beam, X-ray, ultraviolet light, gamma rays, plasma, and thermal energy.

12. The method for modifying the polymer film according to claim 11, wherein, The electron beam dose is 10-50 kGy.

13. The method for modifying the polymer film according to claim 1, wherein, The rinsing is performed using an alcohol solution.

14. The method for modifying the polymer film according to claim 13, wherein, After rinsing, the alcohol solution is replaced with distilled water.

15. The method for modifying the polymer film according to claim 1, wherein, When the polymer membrane is a hydrophobic membrane, the crosslinking agent solution also includes a low-molecular-weight alcohol aqueous solution.

16. The method for modifying the polymer film according to claim 1, wherein, The polymer membrane is a microporous membrane.

17. The method for modifying the polymer film according to claim 16, wherein, The polymer membrane is prepared from one or more copolymers or mixtures of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, nitrocellulose, polypropylene, polyethylene, polyolefin polymers, polyamide, polyimide, acrylic polymers, and methacrylic polymers.

18. The method for modifying the polymer film according to claim 1, wherein, The modified polymer membrane has a protein adsorption capacity of less than or equal to 55 μg / cm³. 2 .

19. The method for modifying the polymer film according to claim 1, wherein, The wetting time of the modified polymer film is less than or equal to 5 seconds.

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

21. The method for modifying the polymer film according to claim 1, wherein, The modified polymer film exhibits caustic alkali stability.

22. The method for modifying the polymer film according to claim 21, wherein, After sterilization with caustic alkali, the modified polymer membrane exhibits a wetting time of ≤5 seconds, a change in water flux and bubble point of ≤20%, and a protein adsorption capacity of ≤55 μg / cm³. 2 .

23. The method for modifying the polymer film according to claim 1, wherein, The modified polymer film exhibits high-pressure sterilization stability.

24. The method for modifying the polymer film according to claim 23, wherein, After autoclaving, the modified polymer membrane exhibits a wetting time of ≤5 seconds, a change in water flux and bubble point of ≤20%, and a protein adsorption capacity of ≤55 μg / cm³. 2 .

25. The method for modifying the polymer film according to claim 1, wherein, The modified polymer membrane exhibits gamma sterilization stability.

26. The method for modifying the polymer film according to claim 25, wherein, After gamma sterilization, the modified polymer membrane exhibits a wetting time of ≤5 seconds, a change in water flux and bubble point of ≤20%, and a protein adsorption capacity of ≤55 μg / cm³. 2 .

27. A modified polymer membrane, wherein the modified polymer membrane is obtained by modifying the polymer membrane using the modification method of any one of claims 1 to 15.

28. The modified polymer film according to claim 27, wherein, The polymer membrane is a microporous membrane.

29. The modified polymer film according to claim 28, wherein, The polymer membrane is prepared from one or more copolymers or mixtures of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, cellulose nitrocellulose, polypropylene, polyethylene, polyolefin polymer, polyamide, polyimide, acrylic polymer, and methacrylic polymer.

30. The modified polymer film according to claim 27, wherein, The modified polymer membrane has a protein adsorption capacity of less than or equal to 55 μg / cm³. 2 .

31. The modified polymer film according to claim 27, wherein, The wetting time of the modified polymer film is less than or equal to 5 seconds.

32. The modified polymer film according to claim 27, wherein, The modified polymer membrane exhibits a change in both water flux and bubble point value of less than or equal to 20% compared to the original polymer membrane.

33. The modified polymer film according to claim 27, wherein, The modified polymer film exhibits caustic alkali stability.

34. The modified polymer film according to claim 33, wherein, After sterilization with caustic alkali, the modified polymer membrane exhibits a wetting time of ≤5 seconds, a change in water flux and bubble point of ≤20%, and a protein adsorption capacity of ≤55 μg / cm³. 2 .

35. The modified polymer film according to claim 27, wherein, The modified polymer film exhibits high-pressure sterilization stability.

36. The modified polymer film according to claim 35, wherein, After autoclaving, the modified polymer membrane exhibits a wetting time of ≤5 seconds, a change in water flux and bubble point of ≤20%, and a protein adsorption capacity of ≤55 μg / cm³. 2 .

37. The modified polymer film according to claim 27, wherein, The modified polymer membrane exhibits gamma sterilization stability.

38. The modified polymer film according to claim 37, wherein, After gamma sterilization, the modified polymer membrane exhibits a wetting time of ≤5 seconds, a change in water flux and bubble point of ≤20%, and a protein adsorption capacity of ≤55 μg / cm³. 2 .

39. The modified polymer film according to claim 27, wherein, The modified polymer membrane is used in a filtration device.

40. A filtration device comprising a housing having a fluid inlet and a fluid outlet, wherein the housing contains a modified polymer membrane as described in claim 27.

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