Modification method of polymer gas-permeable membrane, modified polymer gas-permeable membrane and gas filtering device

Abstract

According to the modification method of the polymer gas-permeable membrane, a hybrid organic silicon coating is covalently bonded or chemically bonded to the inner surface of a pore channel of the polymer gas-permeable membrane by controlling the coating thickness of sol-gel penetrating through the polymer gas-permeable membrane, and the original porous structure of the polymer gas-permeable membrane is kept. The sol-gel solution provided by the invention has the advantages of long working life, no need of special surface modification equipment, simple process, low cost, good industrial amplification and large-scale production capacity. The chemical stability and the sterilization stability of the modified polymer ventilation membrane are remarkably improved, and the hydrophobic performance of the membrane is effectively improved on the premise that the air permeability and the water invasion pressure are not affected, so that the modified polymer ventilation membrane is suitable for the application fields of ventilation and fluid management with high performance requirements. The gas filtering device based on the modified polymer ventilation membrane is low in cost and high in performance and has high practical value.

Description

Technical Field

[0001] This invention belongs to the field of ventilation and fluid management applications with high performance requirements, and specifically relates to a method for modifying a polymer ventilation membrane, the modified polymer ventilation membrane, and a gas filtration device. Background Technology

[0002] Hydrophobic membranes, which allow gas to pass through while effectively preventing liquid penetration, are widely used in gas filtration. Existing hydrophobic ventilation media mainly include polytetrafluoroethylene (PTFE) membranes and polyvinylidene fluoride (PVDF) membranes. These structures typically require high levels of fluorination to resist low-surface-tension liquids, resulting in relatively high material costs. Furthermore, they often exhibit insufficient stability when subjected to ionizing radiation sterilization processes (such as gamma ray irradiation), frequently accompanied by a decrease in mechanical properties. Therefore, these materials have significant limitations in applications requiring both high air permeability and excellent, durable liquid repellency.

[0003] Polyethersulfone (PES) membranes have a wide range of applications in the filtration field. Compared with polytetrafluoroethylene (PTFE) membranes, PES membranes are more stable during gamma irradiation sterilization. However, traditional PES membranes have low hydrophobicity and are prone to wetting under pressure or when in contact with liquids containing surfactants or low surface tension, which leads to a decrease in air permeability.

[0004] US Patent 5,554,414 discloses a method for preparing a composite porous membrane with a crosslinked fluoropolymer surface. This method involves impregnating a porous polymer substrate with a polar solvent solution of an olefinically unsaturated monomer with fluoroalkyl substituents, combined with a crosslinking agent and a polymerization initiator. Subsequently, the impregnated article is exposed to external energy (e.g., ultraviolet light or heat) to achieve in-situ polymerization and crosslinking. This method relies on external energy to initiate the polymerization reaction, thereby creating a hydrophobic or oleophobic fluoropolymer surface layer on the substrate surface.

[0005] U.S. Patent No. 6,355,081 describes a hydrophobic and oleophobic vent filter prepared by coating a polymer substrate with an organopolysiloxane composition. The disclosed system uses vinyl-terminated siloxanes and silane crosslinking agents in the presence of a platinum catalyst to produce a crosslinked PDMS-type coating designed to increase water intrusion pressure while maintaining or moderately increasing permeability. However, the patent does not disclose or suggest the formation of an inorganic hybrid organosiloxane network resulting from the co-condensation of tetraethyl orthosilicate (TEOS) and fluoroalkyltrialkoxysilanes such as 1H, 1H, 2H, 2H perfluorodecyltriethoxysilane (PFDTES), nor does it teach or envision the formation of a covalently bonded fluorinated silica nanoscale layer on the internal pore walls of a porous membrane.

[0006] US Patent 6,579,342 teaches the grafting of fluorosulfonate acrylate oligomers from aqueous or alcoholic solutions onto polysulfone or PVDF membranes via UV irradiation to provide hydrophobic and oleophobic permeable media. These systems rely on an organic fluoropolymer graft layer attached to a polymer substrate. While this grafting method provides liquid-repellent properties to the membrane, the patent neither addresses nor achieves the formation of an inorganic sol-gel-derived fluorosilicone network within the internal pore structure of the PES membrane. Furthermore, the increase in water intrusion pressure is limited in these systems, and permeability may decrease at the higher graft densities required for strong oleophobicity.

[0007] U.S. Patent Application Publication No. 2014 / 0238263 A1 discloses superhydrophobic coatings formed from nanostructured fluorinated silica bodies derived from the sol-gel reaction of TEOS and fluorinated alkoxysilanes (e.g., heptadecafluorotrimethoxysilane). These coatings are applied as continuous thin films to solid substrates such as glass, metal, or polymer sheets, achieving a water contact angle of at least 165°. This patent addresses only outer surface coatings and does not teach or suggest forming conformal nanolayers within porous substrates, nor does it address the challenges of maintaining gas permeability or preventing pore clogging in ventilated membrane applications.

[0008] U.S. Patent Application Publication No. 2008 / 0113188 A1 describes a hybrid organic-inorganic silane sol-gel coating comprising an epoxypropoxysilane and a coupling agent for forming a hydrophobic, corrosion-resistant film on a metallic substrate. The coating disclosed in this patent is a dense, continuous film with a thickness of approximately 0.3-3 μm for corrosion protection, rather than a breathable membrane for ventilation applications, and does not address or resolve issues related to the functionalization of internal pores or the maintenance of permeability within the membrane.

[0009] International Publication No. WO 2019 / 045732 A1 discloses a non-fluorinated waterborne superhydrophobic coating that utilizes hydrophobic polyolefins or wax emulsions combined with plant-based particles (such as cellulose fibers, lycophyll spores, and microcrystalline cellulose) to construct a multi-level surface roughening structure, thereby achieving a water contact angle greater than 150°. This system only forms an external surface treatment and does not disclose modification of the internal pore network of the porous venting membrane. The system disclosed in this patent does not describe an inorganic SiO2-based network suitable for internal nanostructures or superhydrophobic venting under condensation or splash loading conditions.

[0010] U.S. Patent No. 4,954,256 teaches irradiating a microporous substrate in the presence of a polymerizable perfluoroalkyl monomer to graft hydrophobic perfluorinated chains and reduce the critical wetting surface tension to below about 28 dynes / cm. While this method can produce highly hydrophobic films, it does not involve the formation of an inorganic-organic hybrid nanolayer within the membrane pores.

[0011] Therefore, there is a need for a modification technique for polymer breathable membranes that can transform such membranes into superhydrophobic materials with high hydrophobicity. At the same time, there is a need for a practical and scalable method that can impart uniform superhydrophobicity to the membrane while maintaining sufficient breathability and achieving high water intrusion pressure. Summary of the Invention

[0012] To overcome the deficiencies of the prior art, one object of the present invention is to provide a method for modifying a polymer ventilation membrane; another object of the present invention is to provide a modified polymer ventilation membrane; and yet another object of the present invention is to provide a gas filtration device. To achieve the above objects, the technical solutions adopted by the present invention are as follows: One aspect of the present invention provides a method for modifying a polymer breathable membrane, comprising the following steps: Preparation of sol-gel solutions; The sol-gel solution is brought into contact with the surface of the polymer breathable membrane; The coating thickness of the sol-gel solution penetrating the polymer ventilation membrane is controlled to covalently or chemically bond the hybrid organosilicon coating to the inner surface of the pores of the polymer ventilation membrane while maintaining the original porous structure of the polymer ventilation membrane. Remove excess solution from the surface of the polymer ventilation membrane and dry it to obtain the modified polymer ventilation membrane.

[0013] Optionally, the hybrid silicone coating extends at least 50% along the internal pore tortuosity of the polymer venting membrane.

[0014] Optionally, the coating thickness of the sol-gel solution through the polymer ventilated membrane can be controlled by floating saturation, vacuum-assisted coating, or metering coating.

[0015] Optionally, the sol-gel solution comprises alkoxysilane, hydrophobic silane, deionized water, acidic catalyst, and ethanol, wherein: Alkoxysilanes: >1.0 wt% Hydrophobic silane: >0.5 wt% Deionized water: >1.0 wt% Acidic catalyst: >0.1 wt%.

[0016] Optionally, the alkoxysilane comprises at least one tetraalkoxysilane, trialkoxysilane, or organic functional alkoxysilane.

[0017] Optionally, the alkoxysilane is at least one of tetraethoxysilane (TEOS), tetramethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, epoxypropoxypropyltrimethoxysilane, or aminopropyltriethoxysilane.

[0018] Optionally, the hydrophobic silane comprises at least one compound of a fluorinated silane, a perfluoropolyether functional silane, or a long-chain alkyl silane.

[0019] Optionally, the hydrophobic silane is at least one of a fluoroalkyl silane containing a C4–C12 perfluoroalkyl group, a perfluoropolyether silane, or an alkyl silane containing a C6–C22 hydrocarbon chain.

[0020] Optionally, the hybrid organosilicon coating is a nanostructured fluorinated silica layer, which is formed from a sol-gel intermediate formed by the co-condensation of the alkoxysilane and hydrophobic silane.

[0021] Optionally, the fluorosilica layer is cured at a temperature of 60°C-120°C to form a fluorosilicone network that adheres to the surface of the polymer venting membrane and the inner surface of the pores.

[0022] Optionally, the following steps are included: The sol-gel solution was diluted with ethanol; The diluted sol-gel solution is brought into contact with the surface of the polymer breathable membrane; The coating thickness of the diluted sol-gel solution through the polymer ventilation membrane is controlled to covalently or chemically bond the hybrid organosilicon coating to the inner surface of the pores of the polymer ventilation membrane while maintaining the original porous structure of the polymer ventilation membrane. Remove excess solution from the surface of the polymer ventilation membrane and dry it to obtain the modified polymer ventilation membrane.

[0023] Optionally, the modified polymer ventilation membrane is a polyethersulfone ventilation membrane.

[0024] Optionally, the modified polymer breathable membrane has a wetting time of more than 60 seconds with 100 wt% isopropanol (IPA).

[0025] Optionally, the surface tension of the modified polymer breathable membrane is 15.9-21.7 mN / m.

[0026] Optionally, the modified polymer breathable membrane has an air permeability greater than 200 m³ / (hr·m²).

[0027] Optionally, the modified polymer ventilated membrane has a water intrusion pressure greater than 60 psi.

[0028] Optionally, the modified polymer venting membrane has a pore size reduction of less than 30% compared to the unmodified polymer venting membrane.

[0029] Optionally, the air permeability of the modified polymer breathable membrane is at least 75% of that of the unmodified polymer breathable membrane.

[0030] Another aspect of the present invention provides a modified polymer ventilation membrane, prepared according to the aforementioned method for modifying polymer ventilation membranes, wherein the modified polymer ventilation membrane is a polyethersulfone ventilation membrane.

[0031] Optionally, the modified polymer breathable membrane has a wetting time of more than 60 seconds with 100 wt% isopropanol (IPA).

[0032] Optionally, the surface tension of the modified polymer breathable membrane is 15.9-21.7 mN / m.

[0033] Optionally, the modified polymer breathable membrane has an air permeability greater than 200 m³ / (hr·m²).

[0034] Optionally, the modified polymer ventilated membrane has a water intrusion pressure greater than 60 psi.

[0035] Optionally, the modified polymer venting membrane has a pore size reduction of less than 30% compared to the unmodified polymer venting membrane.

[0036] Optionally, the air permeability of the modified polymer breathable membrane is at least 75% of that of the unmodified polymer breathable membrane.

[0037] Another aspect of the present invention provides a gas filtration device, including a housing having a gas-permeable, liquid-blocking inlet and outlet, and the housing having a modified polymer venting membrane as described above.

[0038] The modification method of the polymer ventilation membrane of the present invention controls the coating thickness of the sol-gel through the polymer ventilation membrane by floating, vacuum-assisted, or metered coating. This covalently or chemically bonds the hybrid organosilicon coating to the inner surface of the pores of the polymer ventilation membrane while maintaining the original porous structure of the membrane, avoiding uneven coating modification, and preserving the effective pore size of the polymer filter membrane. The present invention can control the contact angle, water intrusion pressure, and wetting behavior by adjusting the ratio of alkoxysilane to hydrophobic silane. The sol-gel solution of the present invention has a long pot life (>2 weeks), requires no special surface modification equipment such as ultraviolet radiation sources, plasma treatment systems, or electron beam devices, and features a simple process, low cost, and good industrial scalability and mass production capability. The modified polymer ventilation membrane of the present invention exhibits significantly improved chemical and sterilization stability, and effectively enhances the hydrophobic properties of the membrane without affecting air permeability and water intrusion pressure. This makes the modified polymer ventilation membrane suitable for ventilation and fluid management applications with high performance requirements, including but not limited to biopharmaceutical processing, medical devices, electronic manufacturing, and chemical processing systems. The gas filtration device based on the modified polymer venting membrane of this invention is low in cost, high in performance, and has high practical value. Attached Figure Description

[0039] After reading the detailed embodiments of the present invention with reference to the accompanying drawings, the reader will gain a clearer understanding of various aspects of the present invention. Figure 1 The pore size distribution of the polymer ventilation membrane in Comparative Example 1 is compared with that of the modified polymer ventilation membrane in Example 2. Figure 2 SEM / EDX image of the cross-section of the polymer ventilation membrane of Comparative Example 1; Figure 3 Here is a SEM / EDX image of the cross-section of the modified polymer ventilation membrane of Example 2; Figure 4 This is a SEM / EDX image of the top surface of the modified polymer ventilated membrane of Example 2. Detailed Implementation

[0040] 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.

[0041] The polymer ventilation membrane described in this invention is polyethersulfone (PES).

[0042] The modification method of the polymer breathable membrane of the present invention is as follows: S1: Preparation of a sol-gel solution; the sol-gel solution comprises alkoxysilane, hydrophobic silane, deionized water, acidic catalyst, and ethanol, wherein: The alkoxysilane has a weight ratio greater than 1.0 wt%, and the alkoxysilane comprises at least one tetraalkoxysilane, trialalkoxysilane, or organofunctional alkoxysilane. Specifically, the alkoxysilane is at least one selected from tetraethoxysilane (TEOS), tetramethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, epoxypropoxypropyltrimethoxysilane, or aminopropyltriethoxysilane.

[0043] The hydrophobic silane has a weight ratio greater than 0.5 wt%, and the hydrophobic silane comprises at least one fluorinated silane, a perfluoropolyether functional silane, or a long-chain alkyl silane compound. Specifically, the hydrophobic silane is at least one of a fluoroalkyl silane containing a C4–C12 perfluoroalkyl group, a perfluoropolyether silane, or an alkyl silane containing a C6–C22 hydrocarbon chain.

[0044] The weight percentage of the deionized water is greater than 1.0 wt%; The acidic catalyst has a weight ratio greater than 0.1 wt%.

[0045] The sol-gel solution undergoes a two-stage reaction: a hydrolysis stage and a condensation stage. Specifically, the acidic catalyst is 1N hydrochloric acid, and deionized water is mixed with the 1N hydrochloric acid to obtain acidified water, which serves as the hydrolysis and condensation catalyst system. The ethanol is anhydrous ethanol, used as the main solvent to equilibrate the sol-gel solution to 100%. Taking TEOS as the alkoxysilane and PFDTES as the hydrophobic silane as an example, the preparation process of the sol-gel solution is described as follows: Hydrolysis stage: The acidified water is added dropwise to the TEOS / PFDTES solution.

[0046] Under acidic conditions, the alkoxy groups (-OEt) on TEOS and PFDTES are cleaved to form silanol (-Si-OH) groups.

[0047] Condensation stage: The silanol groups condense to form a Si-O-Si network in the following manner: • Alcohol condensation (Si–OH + Si–OEt → Si–O–Si + EtOH) • Water condensation (Si–OH + Si–OH → Si–O–Si + H2O) The existence of PFDTES introduces -(CF2) n The CF3 chain is covalently attached to the silica framework, forming an inorganic-organic hybrid network with inherent hydrophobicity.

[0048] Specifically, the above reaction is carried out for no more than 2 hours so that the sol-gel solution reaches a controlled prepolymerization state that is most suitable for pore permeation.

[0049] When the alkoxysilane or the hydrophobic silane is selected from other chemical components that can achieve the above function, the preparation process is similar to the above process and will not be described in detail here.

[0050] S2: Contact the sol-gel solution with the surface of the polymer breathable membrane; S3: Control the coating thickness of the sol-gel solution penetrating the polymer ventilated membrane, covalently or chemically bonding the hybrid organosilicon coating to the inner surface of the pores of the polymer ventilated membrane while maintaining the original porous structure of the polymer ventilated membrane. Specifically, the coating thickness of the sol-gel solution penetrating the polymer ventilated membrane is controlled by a floating saturation method, vacuum-assisted coating, or metering coating. Specifically, the floating saturation method involves the membrane material floating on the surface of a surface-modified chemical solution. Under capillary action, the liquid permeates the porous membrane along its thickness direction. Simultaneously, air previously trapped in the pores can effectively escape from the other side of the membrane in contact with air, thus facilitating the full entry of the coating liquid into the membrane's pore structure and ensuring uniform coating of the membrane's internal pore walls, effectively reducing pore blockage. The vacuum-assisted method involves removing excess liquid from the pores after the permeation treatment by applying a vacuum or using a set of pressure rollers, thereby preventing substantial blockage of the pores while maintaining their basic openness. The metered coating method precisely applies a controllable dose (volume or weight) of the surface-modified chemical solution to the membrane surface and into the membrane body. This method can more effectively control the degree of pore blockage, thereby achieving membrane functionalization while better maintaining or even improving the membrane's permeability.

[0051] Specifically, the hybrid organosilicon coating extends at least 50% along the tortuosity of the internal pores of the polymer breathable membrane. Specifically, the hybrid organosilicon coating is a nanostructured fluorosilica layer, formed from a sol-gel intermediate resulting from the co-condensation of alkoxysilanes and hydrophobic silanes. Specifically, the fluorosilica layer is cured at a temperature of 60°C-120°C to form a fluorosilicone network adhering to the surface of the polymer breathable membrane and the inner surface of the pores. Preferably, the tortuosity extension is at least 70%, more preferably, the tortuosity extension is at least 90%. Specifically, by adjusting the ratio of the sol-gel solution, on the one hand, the sol-gel solution easily penetrates the thickness of the membrane, resulting in a tortuosity extension of over 50%, thereby improving the membrane modification effect; on the other hand, the hybrid organosilicon coating is a thin layer, which does not block the internal pores of the polymer breathable membrane, maintaining the breathability of the polymer breathable membrane. Specifically, the surface properties of the polymer breathable membrane can be effectively controlled by adjusting the concentration of the hydrophobic silane in the sol-gel solution. Increasing the concentration of the hydrophobic silane results in a higher water contact angle, higher water intrusion pressure, and a longer wetting time for the polymer breathable membrane; however, excessively high concentrations of the hydrophobic silane decrease the membrane's permeability. Conversely, decreasing the concentration of the hydrophobic silane leads to a decrease in the membrane's contact angle, a reduction in water intrusion pressure, and a shortening of the wetting time, resulting in a corresponding decrease in hydrophobic properties. Therefore, it is necessary to experimentally adjust the formulation of the sol-gel solution to achieve a balance between the membrane's hydrophobicity and permeability.

[0052] S4: Remove excess solution from the surface of the polymer ventilation membrane and dry it to obtain the modified polymer ventilation membrane.

[0053] In some embodiments of the present invention, the sol-gel solution may be diluted with ethanol after the preparation of the sol-gel solution is completed; The diluted sol-gel solution is brought into contact with the surface of the polymer breathable membrane; The coating thickness of the diluted sol-gel solution through the polymer ventilation membrane is controlled to covalently or chemically bond the hybrid organosilicon coating to the inner surface of the pores of the polymer ventilation membrane while maintaining the original porous structure of the polymer ventilation membrane. Remove excess solution from the surface of the polymer ventilation membrane and dry it to obtain the modified polymer ventilation membrane.

[0054] The modified polymer breathable membrane was subjected to performance testing, and the testing method is as follows: 1. Wetting time A droplet (30-60 µL) of the specified solution is placed on the surface of the modified polymer breathable membrane, and the time (in seconds) required for the modified polymer breathable membrane to wet is recorded. Specifically, the droplet can pass through the wetted portion of the modified polymer breathable membrane. Compared to the unwetted portion, the wetted portion of the modified polymer breathable membrane is transparent. The time required for the wetted portion of the surface of the modified polymer breathable membrane to become transparent is recorded. Generally, a wetting time of less than or equal to 5 seconds is considered to indicate that the membrane material can be wetted instantaneously, and a wetting time of more than 60 seconds is considered to indicate that it is not wettable.

[0055] 2. Water intrusion pressure test The surface-modified polymer membrane is installed in a fixture, and a filter press is installed upstream of the fixture. A certain amount of deionized water is injected into the filter press, which is then connected to a compressed air source. The pressure upstream of the filter press is slowly increased, and it is observed whether any droplets are filtered out downstream of the fixture. Once droplets are observed to be filtered out, the pressure at this point is recorded; this pressure is the water intrusion pressure. The higher the water intrusion pressure, the stronger the membrane material's resistance to water wetting.

[0056] 3. Breathability test The air permeability of the membrane material was tested using an Innova Porometer pore size analyzer. The dried filter membrane sample was installed in the tester and tested using the bubble pressure method. The program was set to slowly apply air pressure to generate a dry curve, and the air permeability was calculated by the system software.

[0057] 4. Bubble point and pore size distribution test Bubble point and pore size distribution were tested using an Innova Porometer pore size analyzer. Before testing, the filter membrane was thoroughly wetted with Galwet (surface tension 15.9 dyn / cm) and then tested using the bubble pressure method inside the testing instrument.

[0058] The bubble point represents the maximum pore size of a membrane. Specifically, the bubble point is the pressure at which the test pressure exceeds the capillary force required to wet the largest pore in a given membrane sample. All other factors, such as the surface tension of the wetting fluid, asymmetry, and constant thickness, result in a higher bubble point value for smaller pores in the membrane sample. Theoretically, the approximate maximum pore size of the membrane sample can be calculated using the Laplace relation based on the bubble point value.

[0059] d = 4γcosθ / ΔP in: d = aperture γ = Fluid surface tension (N / m) ΔP = Bubble point pressure (Pa) θ = contact angle (°).

[0060] 5. SEM / EDX (Scanning Electron Microscopy / Energy Dispersive X-ray Spectrometry) Analysis The surface morphology, cross-sectional structure, and spatial distribution of the surface modifier of the modified polymer breathable membrane were characterized by scanning electron microscopy / energy dispersive X-ray spectroscopy (SEM / EDX) to achieve simultaneous qualitative and quantitative analysis of the micro-region morphology and elemental composition of the membrane material. Among them, the distribution of silicon (Si) was used to characterize the distribution of the inorganic hybrid organosilicon-oxygen network on the surface of the membrane material and the internal pore walls.

[0061] Compare with Example 1 Comparative Example 1 is an unmodified polymer ventilated membrane, specifically, the polymer ventilated membrane is a PES membrane.

[0062] Compare with Example 2 Prepare a sol-gel solution, wherein the sol-gel solution comprises: TEOS: 5 ml; PFDTES: 2.5 ml; Deionized water: 3.2 ml; 1N hydrochloric acid: 1.0 ml; Anhydrous ethanol: 88.3 ml.

[0063] Specifically, acidified water is prepared by mixing deionized water with 1N hydrochloric acid, and the acidified water is added dropwise to a mixed solution of TEOS, PFDTES and anhydrous ethanol while stirring to form the sol-gel solution.

[0064] The polymer breathable membrane is immersed in the sol-gel solution, i.e., the coating thickness of the sol-gel solution penetrating the polymer breathable membrane is controlled by immersion coating. Specifically, the membrane material is completely immersed in a device containing a surface-modifying chemical solution, and the polymer breathable membrane is saturated through a wet saturation process, so that the polymer breathable membrane is substantially completely wetted by the sol-gel solution. A hybrid organosilicon coating is covalently bonded or chemically bonded to the inner surface of the pores of the polymer breathable membrane, while maintaining the original porous structure of the polymer breathable membrane.

[0065] Excess solution is removed from the surface of the polymer breathable membrane using a rubber roller, and the modified polymer breathable membrane is obtained after drying.

[0066] Example 1 The sol-gel solution described in Comparative Example 2 was diluted with ethanol at a volume ratio of 1:1. The coating thickness of the diluted sol-gel solution through the polymer ventilation membrane was controlled by the floating saturation method. Specifically, the polymer ventilation membrane was floated on the surface of the diluted sol-gel solution and kept in contact for about 10 seconds until the polymer ventilation membrane was saturated. This allowed the sol-gel solution to essentially cover all the internal pore walls of the polymer ventilation membrane from the bottom to the top, i.e., through the thickness of the polymer ventilation membrane.

[0067] After the polymer breathable membrane is saturated, excess solution is removed from the surface of the polymer breathable membrane using a rubber roller, and then the polymer breathable membrane is allowed to air dry for about 15 minutes, followed by drying at a temperature of about 115°C for about 60 minutes to obtain the modified polymer breathable membrane.

[0068] Example 2 The sol-gel solution described in Comparative Example 2 was diluted with ethanol at a volume ratio of 1:2. The polymer breathable membrane was placed on a polypropylene spunbond nonwoven support. The diluted sol-gel solution was brought into contact with the upper surface of the polymer breathable membrane. The diluted sol-gel solution was then used in a vacuum chamber to penetrate the coating thickness of the polymer breathable membrane, thereby substantially covering all the internal pore walls of the polymer breathable membrane.

[0069] After the polymer breathable membrane is saturated, excess solution is removed from the surface of the polymer breathable membrane using a rubber roller, and then the polymer breathable membrane is allowed to air dry for about 15 minutes, followed by drying at a temperature of about 115°C for about 60 minutes to obtain the modified polymer breathable membrane.

[0070] Example 3 This embodiment tested the performance of the polymer breathable membrane of Comparative Example 1 and the modified polymer breathable membranes of Comparative Examples 2 (Comparative Examples 2-1 and 2-2) and Example 1 (Examples 1-1 and 1-2). Specifically, the performance tests included IPA wetting time, Galwet wetting time, water intrusion pressure, and air permeability. The test results were compared with those of Comparative Example 1, as detailed in Table 1.

[0071] Table 1:

[0072] As shown in Table 1, when using 100 wt% isopropanol (IPA) for wetting tests, the wetting time of Control Example 1 was less than 1 s, while the wetting time of the modified polymer breathable membranes of Control Examples 2-1, 2-2, and Examples 1-1, 1-2 was greater than 60 s. It can be seen that Control Examples 2-1, 2-2, and Examples 1-1, 1-2 exhibited anti-wetting properties. When using 100 wt% Galwet for wetting tests, the wetting time of Control Examples 1, 2-1, 2-2, and Examples 1-1, 1-2 was less than 1 s. Isopropanol (IPA) has a surface tension of 21.7 mN / m, and Galwet is a fluorowetting agent with a surface tension of 15.9 mN / m. Therefore, it can be inferred that the critical wetting surface tension (CWST) of the modified polymer ventilated membranes of Comparative Examples 2-1, 2-2, and Examples 1-1, 1-2 is approximately in the range of 15.9 mN / m to 21.7 mN / m. Tests showed that Comparative Example 1 exhibited instantaneous wetting upon contact with a 10 wt% IPA solution with a surface tension of 41.2 mN / m, indicating that the hydrophobic properties of the modified polymer ventilated membranes of Comparative Examples 2-1, 2-2, and Examples 1-1, 1-2 were significantly improved. Furthermore, the surface energy of polytetrafluoroethylene (PTFE) is approximately 22 ± 4 mJ / m², indicating that the hydrophobic properties of the modified polymer ventilated membranes of Comparative Examples 2-1, 2-2, and Examples 1-1, 1-2 are comparable to those of PTFE.

[0073] Table 1 also shows that the surface modification coating method and the concentration of the sol-gel solution have a significant impact on air permeability. Specifically, when using wetting coating (Comparative Example 2), the method has limited precision in controlling the dosage of the coating chemical solution, which can easily lead to excessive deposition of modified substances on the membrane surface or inside the pores, resulting in significant pore blockage and potential oversaturation of the membrane material, leading to a significant decrease in air permeability. When using a diluted sol-gel solution (Example 1), both air permeability and water intrusion pressure increase. Therefore, the water intrusion pressure and air permeability of the modified polymer breathable membrane can be adjusted by changing the concentration of the sol-gel solution, achieving an ideal balance between increased water intrusion pressure and acceptable air permeability. Specifically, by adjusting the concentration of hydrophobic silane in the sol-gel solution, the surface properties of the polymer breathable membrane can be effectively controlled. Increasing the concentration of the hydrophobic silane can give the polymer breathable membrane a higher water contact angle, higher water intrusion pressure, and longer wetting time. However, if the concentration of the hydrophobic silane is too high, the breathability of the polymer breathable membrane will decrease. Conversely, decreasing the concentration of the hydrophobic silane will lead to a decrease in the membrane's contact angle, a decrease in water intrusion pressure, and a shortening of the wetting time, thus exhibiting a corresponding decrease in hydrophobic properties. Therefore, it is necessary to adjust the formulation of the sol-gel solution experimentally to achieve a balance between hydrophobicity and breathability.

[0074] Example 4 This embodiment tests the performance of the modified polymer breathable membrane sample from Example 2. Specifically, the performance tests include Galwet bubble point, Galwet average flow rate, pore size, and permeability. The test results are compared with those of Control Example 1, as detailed in Table 2. The comparison of pore size distribution between Control Example 1 and Example 2 is shown in Table 2. Figure 1 .

[0075] Table 2:

[0076] As shown in Table 2, the pore size and permeability of the modified polymer breathable membrane did not change substantially compared to the unmodified polymer breathable membrane. Furthermore, as... Figure 3 As shown, the average flow pore size of the modified polymer venting membrane did not change significantly compared to the unmodified polymer venting membrane.

[0077] Example 5 This embodiment tests the performance of the modified polymer breathable membrane sample from Example 2. Specifically, the performance tests include the wetting time of IPA and Galwet, and the water intrusion pressure. The test temperature is 20.6°C. The test results are compared with those of Control Example 1, as detailed in Table 3.

[0078] Table 3:

[0079] As shown in Table 3, when using 100 wt% IPA for wetting testing, the wetting time of the modified polymer breathable membrane in Example 2 is greater than 60 s. When using 100 wt% Galwet for wetting testing, the wetting time of Example 2 is less than 1 s. Therefore, the critical wetting surface tension (CWST) of the modified polymer breathable membrane in Example 2 is approximately in the range of 15.9 mN / m-21.7 mN / m, which is an improvement in hydrophobicity compared to Control Example 1 and comparable to the hydrophobicity of PTFE.

[0080] The SEM / EDX image of the cross-section of the polymer ventilation membrane of Comparative Example 1 is shown below. Figure 2 SEM / EDX images of the cross-section of the modified polymer ventilation membrane in Example 2 are shown below. Figure 3 SEM / EDX images of the top surface of the modified polymer ventilated membrane in Example 2 are shown below. Figure 4 . Figure 2-4The SEM / EDX images shown indicate that the modification method of the present invention produces a substantially uniform distribution of the sol-gel derived coating not only on the outer surface of the membrane but also across the entire membrane thickness. This structure avoids the non-uniform structure caused by the coating method used in the prior art, thereby avoiding the decrease in air permeability caused by the non-uniform structure.

[0081] Example 6 This embodiment provides a gas filtration device, including a housing, the housing having a gas-permeable inlet and a liquid-blocking outlet, and the housing having a modified polymer venting membrane as described in any of Embodiments 1-2.

[0082] The gas filtration devices include, but are not limited to, sterilization and permeable filters, biopharmaceutical containers, electronic casings, chemical drums, and medical devices.

[0083] The gas filtration device includes, but is not limited to, stacked filters, cartridge filters, bladder filters, spiral wound filters, etc.

[0084] The modified polymer ventilation membrane can be a flat sheet membrane or a hollow fiber membrane.

[0085] The modification method of the polymer ventilation membrane of the present invention controls the coating thickness of the sol-gel through the polymer ventilation membrane by floating, vacuum-assisted, or metered coating. This covalently or chemically bonds the hybrid organosilicon coating to the inner surface of the pores of the polymer ventilation membrane while maintaining the original porous structure of the membrane, avoiding uneven coating modification, and preserving the effective pore size of the polymer filter membrane. The present invention can control the contact angle, water intrusion pressure, and wetting behavior by adjusting the ratio of alkoxysilane to hydrophobic silane. The sol-gel solution of the present invention has a long pot life (>2 weeks), requires no special surface modification equipment such as ultraviolet radiation sources, plasma treatment systems, or electron beam devices, and features a simple process, low cost, and good industrial scalability and mass production capability. The modified polymer ventilation membrane of the present invention exhibits significantly improved chemical and sterilization stability, and effectively enhances the hydrophobic properties of the membrane without affecting air permeability and water intrusion pressure. This makes the modified polymer ventilation membrane suitable for ventilation and fluid management applications with high performance requirements, including but not limited to biopharmaceutical processing, medical devices, electronic manufacturing, and chemical processing systems. The gas filtration device based on the modified polymer venting membrane of this invention is low in cost, high in performance, and has high practical value.

[0086] 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 listed in 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 of modifying a polymeric gas permeable membrane, characterized by, Includes the following steps: Preparation of sol-gel solutions; The sol-gel solution is brought into contact with the surface of the polymer breathable membrane; The coating thickness of the sol-gel solution penetrating the polymer ventilation membrane is controlled to covalently or chemically bond the hybrid organosilicon coating to the inner surface of the pores of the polymer ventilation membrane while maintaining the original porous structure of the polymer ventilation membrane. Remove excess solution from the surface of the polymer ventilation membrane and dry it to obtain the modified polymer ventilation membrane.

2. The method of modifying a polymeric venting film according to claim 1, wherein, The hybrid organosilicon coating extends at least 50% along the tortuosity of the internal pores of the polymer venting membrane.

3. The method of modifying a polymeric venting film according to claim 1, wherein, The coating thickness of the sol-gel solution through the polymer ventilated membrane can be controlled by floating saturation, vacuum-assisted coating, or metering coating.

4. The method of modifying a polymeric venting film according to claim 1, wherein, The sol-gel solution comprises alkoxysilane, hydrophobic silane, deionized water, acidic catalyst, and ethanol, wherein: Alkoxysilanes: >1.0 wt% Hydrophobic silane: >0.5 wt% Deionized water: >1.0 wt% Acidic catalyst: >0.1 wt%.

5. The method of modifying a polymeric venting film according to claim 4, wherein, The alkoxysilane comprises at least one tetraalkoxysilane, trialkoxysilane, or organic functional alkoxysilane.

6. The method of modifying a polymeric venting film according to claim 5, wherein, The alkoxysilane is at least one of tetraethoxysilane (TEOS), tetramethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, epoxypropoxypropyltrimethoxysilane, or aminopropyltriethoxysilane.

7. The method for modifying the polymer breathable membrane according to claim 4, characterized in that, The hydrophobic silane comprises at least one compound of fluorinated silane, perfluoropolyether functional silane, or long-chain alkyl silane.

8. The method for modifying the polymer breathable membrane according to claim 7, characterized in that, The hydrophobic silane is at least one of a fluoroalkyl silane containing a C4–C12 perfluoroalkyl group, a perfluoropolyether silane, or an alkyl silane containing a C6–C22 hydrocarbon chain.

9. The method for modifying the polymer breathable membrane according to claim 4, characterized in that, The hybrid organosilicon coating is a nanostructured fluorinated silica layer, which is formed from a sol-gel intermediate formed by the co-condensation of alkoxysilane and hydrophobic silane.

10. The method for modifying the polymer breathable membrane according to claim 9, characterized in that, The fluorinated silica layer is cured at a temperature of 60℃-120℃ to form a fluorinated silica network that adheres to the surface of the polymer ventilated membrane and the inner surface of the pores.

11. The method for modifying the polymer breathable membrane according to claim 1, characterized in that, Includes the following steps: The sol-gel solution was diluted with ethanol; The diluted sol-gel solution is brought into contact with the surface of the polymer breathable membrane; The coating thickness of the diluted sol-gel solution through the polymer ventilation membrane is controlled to covalently or chemically bond the hybrid organosilicon coating to the inner surface of the pores of the polymer ventilation membrane while maintaining the original porous structure of the polymer ventilation membrane. Remove excess solution from the surface of the polymer ventilation membrane and dry it to obtain the modified polymer ventilation membrane.

12. The method for modifying the polymer breathable membrane according to claim 1, characterized in that, The modified polymer ventilation membrane is a polyethersulfone ventilation membrane.

13. The method for modifying the polymer breathable membrane according to claim 1, characterized in that, The modified polymer breathable membrane has a wetting time of more than 60 seconds with 100 wt% isopropanol (IPA).

14. The method for modifying the polymer breathable membrane according to claim 1, characterized in that, The surface tension of the modified polymer breathable membrane is 15.9-21.7 mN / m.

15. The method for modifying the polymer breathable membrane according to claim 1, characterized in that, The modified polymer breathable membrane has an air permeability greater than 200 m³ / (hr·m²).

16. The method for modifying the polymer breathable membrane according to claim 1, characterized in that, The modified polymer ventilated membrane has a water intrusion pressure greater than 60 psi.

17. The method for modifying the polymer breathable membrane according to claim 1, characterized in that, The modified polymer venting membrane has a pore size reduction of less than 30% compared to the unmodified polymer venting membrane.

18. The method for modifying the polymer breathable membrane according to claim 1, characterized in that, The modified polymer breathable membrane has an air permeability of at least 75% that of the unmodified polymer breathable membrane.

19. A modified polymer ventilation membrane, prepared according to the modification method of the polymer ventilation membrane according to claim 1, characterized in that, The modified polymer ventilation membrane is a polyethersulfone ventilation membrane.

20. The modified polymer breathable membrane according to claim 19, characterized in that, The modified polymer breathable membrane has a wetting time of more than 60 seconds with 100 wt% isopropanol (IPA).

21. The modified polymer breathable membrane according to claim 19, characterized in that, The surface tension of the modified polymer breathable membrane is 15.9-21.7 mN / m.

22. The modified polymer breathable membrane according to claim 19, characterized in that, The modified polymer breathable membrane has an air permeability greater than 200 m³ / (hr·m²).

23. The modified polymer breathable membrane according to claim 19, characterized in that, The modified polymer ventilated membrane has a water intrusion pressure greater than 60 psi.

24. The modified polymer breathable membrane according to claim 19, characterized in that, The modified polymer venting membrane has a pore size reduction of less than 30% compared to the unmodified polymer venting membrane.

25. The modified polymer breathable membrane according to claim 19, characterized in that, The modified polymer breathable membrane has an air permeability of at least 75% that of the unmodified polymer breathable membrane.

26. A gas filtration device, comprising a housing having a gas-permeable, liquid-blocking inlet and outlet, characterized in that, The outer casing is provided with the modified polymer ventilated membrane as described in claim 19.

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