High-strength ePTFE skeleton microporous membrane and preparation method thereof

Abstract

The invention relates to the technical field of membrane materials, in particular to a high-strength ePTFE framework microporous membrane and a preparation method thereof. The preparation method comprises the following steps: S1, uniformly mixing polytetrafluoroethylene resin and isododecane, standing for curing, extruding into sheets, and drying and degreasing to obtain a polytetrafluoroethylene film; s2, carrying out stretching treatment and heat setting on the polytetrafluoroethylene film to obtain an ePTFE skeleton microporous film; and S3, carrying out plasma surface activation treatment on the ePTFE skeleton microporous membrane, soaking the ePTFE skeleton microporous membrane in a surface modification solution for 15-25 minutes, adding a glutaraldehyde solution, carrying out a reaction for 1-2 hours, and carrying out cleaning and drying to obtain the high-strength ePTFE skeleton microporous membrane. The surface modification solution is prepared by compounding 50-60 parts by mass of a polyvinyl alcohol solution, 20-30 parts by mass of a modified polyethyleneimine solution and 10-20 parts by mass of a modified chitosan solution.

Description

Technical Field

[0001] The present invention relates to the technical field of membrane materials, in particular to a high-strength ePTFE skeleton microporous membrane and a preparation method thereof. Background Art

[0002] With technological advancements and industrial development, microporous membrane materials have found widespread application in fields such as filtration, separation, gas permeation, and medical devices. Polytetrafluoroethylene (PTFE), in particular, has become a key material in the microporous membrane field due to its excellent chemical resistance, high-temperature resistance, and low coefficient of friction. Expanded polytetrafluoroethylene (ePTFE), a new polymer material made from PTFE resin through specialized processing methods such as stretching, is particularly suitable for applications requiring high strength and high air permeability.

[0003] In recent years, the market demand for high-strength ePTFE skeleton microporous membranes has continued to increase. This membrane material is required not only to have good air permeability and filtration performance, but also to have high mechanical strength and durability to adapt to harsh working environments. However, traditional ePTFE membranes often fail to meet the strength requirements of certain industrial applications, especially under conditions of high pressure or high flow rate, and are prone to rupture or deformation. In addition, PTFE is highly hydrophobic, which limits its application in water treatment and poses a serious problem of membrane fouling, which greatly restricts its application.

[0004] Therefore, we propose a high-strength ePTFE skeleton microporous membrane and a preparation method thereof. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-strength ePTFE skeleton microporous membrane and a preparation method thereof, so as to solve the problems raised in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions: A method for preparing a high-strength ePTFE skeleton microporous membrane comprises the following steps: Step S1: uniformly mixing polytetrafluoroethylene resin and isododecane, allowing to stand for aging, extruding into sheets, and drying and degreasing to obtain a polytetrafluoroethylene film; Step S2: stretching the polytetrafluoroethylene film and heat-setting it to obtain an ePTFE skeleton microporous membrane; Step S3: The ePTFE skeleton microporous membrane is subjected to plasma surface activation treatment, immersed in a surface modification solution for 15-25 minutes, and then added with glutaraldehyde solution for reaction for 1-2 hours. After washing and drying, a high-strength ePTFE skeleton microporous membrane is obtained.

[0007] Furthermore, the mass ratio of the polytetrafluoroethylene to isododecane is 10:(1-3).

[0008] Furthermore, the stretching treatment includes longitudinal stretching and transverse stretching; the stretching temperature of the longitudinal stretching is 40-300°C, the stretching ratio is 50-1000%, and the stretching spacing is 20-200mm; the stretching temperature of the transverse stretching is 20-300°C, the stretching ratio is 50-2000%, and the stretching spacing is 20-200mm.

[0009] Furthermore, the drying and degreasing treatment is performed at a temperature of 150-280° C. and for a treatment time of 5-30 minutes.

[0010] Furthermore, the atmosphere of the plasma surface activation treatment is air, the radio frequency power is 20-140W, and the treatment time is 1-10 minutes.

[0011] Furthermore, the surface modification solution is prepared by compounding 50-60 parts by mass of polyvinyl alcohol solution, 20-30 parts by mass of modified polyethyleneimine solution, and 10-20 parts by mass of modified chitosan solution.

[0012] Furthermore, the preparation method of the modified polyethyleneimine solution is as follows: The polyethyleneimine and phosphate buffer were mixed evenly, the pH of the system was adjusted to 5.0-5.5 using nitric acid, chlorogenic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were added, and the reaction was carried out for 2-3 hours. A mixed solution of graphene oxide and deionized water was added dropwise for 1-2 hours, and the mixture was reacted for 6-8 hours to obtain a modified polyethyleneimine solution.

[0013] Furthermore, the mass ratio of the polyethyleneimine, phosphate buffer, chlorogenic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide is 1:(15-20):(0.5-0.7):(0.9-1.0), and the concentration of nitric acid is 1M.

[0014] Furthermore, the concentration of the mixed solution is 10 mg / mL, and its mass is 100-120 times the mass of polyethyleneimine.

[0015] Furthermore, the preparation method of the modified chitosan solution is as follows: Step A: Evenly mix the epoxy-terminated allyl polyether and 3-aminopropyltriethoxysilane, and react at 40-60° C. for 5-7 hours to obtain a silicone-modified allyl polyether; Step B: uniformly mixing organosilicon-modified allyl polyether, L-cysteine ​​and ethanol, adding a photoinitiator, and irradiating with ultraviolet light to obtain modified L-cysteine; Step C: Mix the MES buffer solution and modified L-cysteine ​​evenly, add 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide, react in the dark for 30-40 minutes, add chitosan, adjust the pH to 7-7.5, and react for 12-24 hours to obtain a modified chitosan solution.

[0016] Furthermore, in step A, the molar ratio of the epoxy group in the epoxy-terminated allyl polyether to the 3-aminopropyltriethoxysilane is 1:(1.0-1.2).

[0017] Furthermore, in the step B, the mass ratio of the organosilicon-modified allyl polyether, L-cysteine, ethanol and photoinitiator is 1:(2-4):(10-12):(0.1-0.3).

[0018] Furthermore, the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0019] Furthermore, the process conditions of the ultraviolet irradiation are: irradiation with 360-400nm ultraviolet rays for 30-50min, irradiation intensity of 25-35mW / cm 2 .

[0020] Furthermore, the mass ratio of the modified L-cysteine ​​to the MES buffer solution is 1:(50-100), and the concentration of the MES buffer solution is 0.1 mol / L.

[0021] Furthermore, the mass ratio of the modified L-cysteine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide and chitosan is 1:(0.7-0.9):(1.0-1.2):(0.3-0.5).

[0022] Furthermore, the concentration of the glutaraldehyde solution is 2-4 wt %, and the amount thereof is 1-2 times the mass of the surface modification solution.

[0023] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention discloses a high-strength ePTFE skeleton microporous membrane and its preparation method, which utilizes a surface modification solution composed of a polyvinyl alcohol solution, a modified polyethyleneimine solution, and a modified chitosan solution to effectively improve the membrane's hydrophilicity and anti-fouling properties. The modified PEI, by introducing chlorogenic acid containing a catechol structure and graphene oxide (GO), not only enhances the solution's hydrophilicity and adhesion, thereby reducing membrane fouling, but the addition of GO also significantly improves the mechanical strength and thermal stability of the resulting composite membrane. The epoxy-terminated allyl polyether with bifunctional groups (allyl and epoxy groups) is modified by 3-aminopropyl triethoxysilane (APTES) to obtain a silicone-modified allyl polyether; then, the silicone chain segment and the polyether structure are introduced onto L-cysteine by using a high-efficiency thiol-ene click reaction to prepare modified L-cysteine; finally, the modified L-cysteine is firmly grafted onto the chitosan skeleton by activating the carboxyl group through EDC / NHS, so as to endow the film with excellent antibacterial performance.

[0024] 2. The high-strength ePTFE skeleton microporous membrane and the preparation method thereof, the active groups are introduced by plasma surface activation treatment on the ePTFE skeleton microporous membrane, and then the amino groups in the surface modification solution are crosslinked with the glutaraldehyde solution to form a layer of film on the surface, this process not only enhances the strength of the membrane, but also improves the surface hydrophilicity and anti-pollution ability of the membrane, so that the stability of the membrane in a high-pressure or high-flow environment is significantly improved, and the harsh requirements of industrial applications are met. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0026] The polytetrafluoroethylene resin in the embodiment is CGF216G from Zhonghao Chen Guang Chemical Research Institute; the isododecane is ISOPAR-H; the graphene oxide has a thickness of 1-3 nm, a diameter of 4-7 mu m, and 2-5 layers; the epoxy-terminated allyl polyether is KL-11 from Liaoning Kelong Fine Chemical Co., Ltd.; the polyvinyl alcohol is PVA205 from Japan Kao Lai; and the polyethyleneimine is G-35 from Wuhan Bolai Chemical Co., Ltd.

[0027] The following parts are mass parts unless otherwise specified.

[0028] Embodiment 1: A preparation method of a high-strength ePTFE skeleton microporous membrane, comprising the following processes: Step S1: 100 parts of polytetrafluoroethylene resin and 10 parts of isododecane are uniformly mixed, allowed to stand and mature, extruded into a sheet, and dried and defatted (temperature 150 DEG C, time 30 min) to obtain a polytetrafluoroethylene film; Step S2: longitudinally stretching the polytetrafluoroethylene film at a stretching temperature of 200° C., a stretching ratio of 600%, and a stretching distance of 150 mm; then transversely stretching the longitudinally stretched polytetrafluoroethylene film at a stretching temperature of 40° C., a stretching ratio of 200%, and heat setting to obtain an ePTFE skeleton microporous membrane; Step S3: The ePTFE skeleton microporous membrane was subjected to plasma surface activation treatment (air atmosphere, radio frequency power of 20 W, treatment time 10 minutes), immersed in a surface modification solution for 15 minutes (solid-to-liquid ratio of 1:15), and then added with a 2 wt % glutaraldehyde solution for 1 hour. After washing and drying, a high-strength ePTFE skeleton microporous membrane was obtained; the amount of glutaraldehyde solution used was 1 times the mass of the surface modification solution; The surface modification solution is prepared by compounding 50 parts by mass of 5 wt% polyvinyl alcohol solution, 20 parts by mass of modified polyethyleneimine solution, and 10 parts by mass of modified chitosan solution; The preparation method of modified polyethyleneimine solution is as follows: 1 part of polyethyleneimine and 15 parts of phosphate buffer were mixed evenly, and the pH of the system was adjusted to 5.0 with 1 M nitric acid. 0.5 parts of chlorogenic acid and 0.9 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were added and reacted for 2 h. 100 parts of a mixed solution of 10 mg / L graphene oxide and deionized water were added dropwise and added for 1 h. The mixture was reacted for 6 h to obtain a modified polyethyleneimine solution. The preparation method of modified chitosan solution is as follows: Step A: Evenly mixing epoxy-terminated allyl polyether and 3-aminopropyltriethoxysilane, and reacting at 40° C. for 5 hours to obtain silicone-modified allyl polyether; the molar ratio of epoxy groups in the epoxy-terminated allyl polyether to those in 3-aminopropyltriethoxysilane is 1:(1.0-1.2); Step B: 1 part of organosilicon-modified allyl polyether, 2 parts of L-cysteine, and 10 parts of ethanol were mixed evenly, 0.1 part of 2-hydroxy-2-methyl-1-phenyl-1-propanone was added, and the mixture was irradiated with ultraviolet light to obtain modified L-cysteine; Step C: Mix 50 parts of 0.1 mol / L MES buffer solution and 1 part of modified L-cysteine, add 0.7 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 1 part of N-hydroxysuccinimide, react in the dark for 30 minutes, add 0.3 parts of chitosan, adjust the pH to 7, and react for 12 hours to obtain a modified chitosan solution.

[0029] Example 2: A method for preparing a high-strength ePTFE skeleton microporous membrane, comprising the following processes: Step S1: 100 parts of polytetrafluoroethylene resin and 20 parts of isododecane are mixed evenly, left to stand for aging, extruded into sheets, and dried and degreased (temperature 200°C, time 10 minutes) to obtain a polytetrafluoroethylene film; Step S2: longitudinally stretching the polytetrafluoroethylene film at a stretching temperature of 200° C., a stretching ratio of 600%, and a stretching distance of 150 mm; then transversely stretching the longitudinally stretched polytetrafluoroethylene film at a stretching temperature of 40° C., a stretching ratio of 200%, and heat setting to obtain an ePTFE skeleton microporous membrane; Step S3: The ePTFE skeleton microporous membrane was subjected to plasma surface activation treatment (air atmosphere, RF power of 50 W, treatment time of 5 minutes), immersed in a surface modification solution for 20 minutes (solid-to-liquid ratio of 1:18), and then added with a 3wt% glutaraldehyde solution to react for 1.5 hours. After washing and drying, a high-strength ePTFE skeleton microporous membrane was obtained; the amount of glutaraldehyde solution used was 1.5 times the mass of the surface modification solution; The surface modification solution is prepared by compounding 55 parts by mass of 8 wt% polyvinyl alcohol solution, 25 parts by mass of modified polyethyleneimine solution, and 15 parts by mass of modified chitosan solution; The preparation method of modified polyethyleneimine solution is as follows: 1 part of polyethyleneimine and 18 parts of phosphate buffer were mixed evenly, and the pH of the system was adjusted to 5.2 with 1 M nitric acid. 0.6 parts of chlorogenic acid and 0.95 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were added and reacted for 2.5 hours. 110 parts of a 10 mg / mL mixed solution of graphene oxide and deionized water were added dropwise over 1.5 hours. The mixture was allowed to react for 7 hours to obtain a modified polyethyleneimine solution. The preparation method of modified chitosan solution is as follows: Step A: The epoxy-terminated allyl polyether and 3-aminopropyltriethoxysilane were mixed uniformly and reacted at 50° C. for 6 hours to obtain a silicone-modified allyl polyether; the molar ratio of the epoxy group in the epoxy-terminated allyl polyether to the 3-aminopropyltriethoxysilane was 1:1.1; Step B: 1 part of organosilicon-modified allyl polyether, 3 parts of L-cysteine, and 11 parts of ethanol were uniformly mixed, 0.2 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone were added, and the mixture was irradiated with ultraviolet light to obtain modified L-cysteine; Step C: Mix 80 parts of 0.1 mol / L MES buffer solution and 1 part of modified L-cysteine, add 0.8 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 1.1 parts of N-hydroxysuccinimide, react in the dark for 35 minutes, add 0.4 parts of chitosan, adjust the pH to 7.4, and react for 20 hours to obtain a modified chitosan solution.

[0030] Example 3: A method for preparing a high-strength ePTFE skeleton microporous membrane, comprising the following steps: Step S1: 100 parts of polytetrafluoroethylene resin and 30 parts of isododecane are mixed evenly, allowed to stand for aging, extruded into sheets, and dried and degreased (temperature 280°C, time 5 minutes) to obtain a polytetrafluoroethylene film; Step S2: longitudinally stretching the polytetrafluoroethylene film at a stretching temperature of 200° C., a stretching ratio of 600%, and a stretching distance of 150 mm; then transversely stretching the longitudinally stretched polytetrafluoroethylene film at a stretching temperature of 40° C., a stretching ratio of 200%, and heat setting to obtain an ePTFE skeleton microporous membrane; Step S3: The ePTFE skeleton microporous membrane was subjected to plasma surface activation treatment (air atmosphere, radio frequency power of 140 W, treatment time of 1 minute), immersed in a surface modification solution for 25 minutes (solid-to-liquid ratio of 1:20), and then added with 4wt% glutaraldehyde solution for 2 hours. After washing and drying, a high-strength ePTFE skeleton microporous membrane was obtained; The surface modification solution is prepared by compounding 60 parts by mass of 10 wt% polyvinyl alcohol solution, 30 parts by mass of modified polyethyleneimine solution, and 0.20 parts by mass of modified chitosan solution; The preparation method of modified polyethyleneimine solution is as follows: 1 part of polyethyleneimine and 20 parts of phosphate buffer were mixed evenly, and the pH of the system was adjusted to 5.5 with 1 M nitric acid. 0.7 parts of chlorogenic acid and 1 part of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were added and reacted for 3 hours. 120 parts of a mixed solution of 10 mg / mL graphene oxide and deionized water were added dropwise and the mixture was added for 2 hours. The mixture was reacted for 8 hours to obtain a modified polyethyleneimine solution. The preparation method of modified chitosan solution is as follows: Step A: 1 part of epoxy-terminated allyl polyether and 3-aminopropyltriethoxysilane were mixed evenly and reacted at 60° C. for 7 hours to obtain a silicone-modified allyl polyether; the molar ratio of epoxy groups in the epoxy-terminated allyl polyether to those in 3-aminopropyltriethoxysilane was 1:1.2; Step B: 1 part of organosilicon-modified allyl polyether, 4 parts of L-cysteine, and 12 parts of ethanol were uniformly mixed, 0.3 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone were added, and the mixture was irradiated with ultraviolet light to obtain modified L-cysteine; Step C: Mix 100 parts of 0.1 mol / L MES buffer solution and 1 part of modified L-cysteine, add 0.9 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 1.2 parts of N-hydroxysuccinimide, react in the dark for 40 minutes, add 0.5 parts of chitosan, adjust the pH to 7.5, and react for 24 hours to obtain a modified chitosan solution.

[0031] Preparation method of a high-strength ePTFE skeleton microporous membrane, comprising the following processes: Step S1: 100 parts of polytetrafluoroethylene resin and 20 parts of isododecane were uniformly mixed, allowed to stand and mature, extruded into a sheet, and after drying and defatting treatment (temperature 200°C, time 10 min), a polytetrafluoroethylene film was obtained; Step S2: The polytetrafluoroethylene film was first stretched longitudinally, the stretching temperature was 200°C, the stretching ratio was 600%, and the stretching interval was 150 mm; the longitudinally stretched polytetrafluoroethylene film was transversely stretched, the stretching temperature was 40°C, the stretching ratio was 200%, and heat setting was performed, to obtain an ePTFE skeleton microporous membrane; Step S3: The ePTFE skeleton microporous membrane was subjected to plasma surface activation treatment (atmosphere: air, radio frequency power: 50W, treatment time: 5 min), soaked in a surface modification solution for 20 min (solid-liquid ratio: 1:18), and then 3wt% glutaraldehyde solution was added for reaction for 1.5h, and after washing and drying, a high-strength ePTFE skeleton microporous membrane was obtained; the amount of glutaraldehyde solution was 1.5 times the mass of the surface modification solution; The surface modification solution was compounded from 55 parts by mass of 8wt% polyvinyl alcohol solution, 25 parts by mass of polyethyleneimine solution, and 15 parts of modified chitosan solution; Compared with Example 2, in Comparative Example 1, the modified polyethyleneimine solution was replaced with the same mass of polyethyleneimine solution, and the other steps were the same as in Example 2.

[0032] Preparation method of a high-strength ePTFE skeleton microporous membrane, comprising the following processes: Step S1: 100 parts of polytetrafluoroethylene resin and 20 parts of isododecane were uniformly mixed, allowed to stand and mature, extruded into a sheet, and after drying and defatting treatment (temperature 200°C, time 10 min), a polytetrafluoroethylene film was obtained; Step S2: The polytetrafluoroethylene film was first stretched longitudinally, the stretching temperature was 200°C, the stretching ratio was 600%, and the stretching interval was 150 mm; the longitudinally stretched polytetrafluoroethylene film was transversely stretched, the stretching temperature was 40°C, the stretching ratio was 200%, and heat setting was performed, to obtain an ePTFE skeleton microporous membrane; Step S3: The ePTFE skeleton microporous membrane was subjected to plasma surface activation treatment (atmosphere: air, radio frequency power: 50W, treatment time: 5 min), soaked in a surface modification solution for 20 min (solid-liquid ratio: 1:18), and then 3wt% glutaraldehyde solution was added for reaction for 1.5h, and after washing and drying, a high-strength ePTFE skeleton microporous membrane was obtained; the amount of glutaraldehyde solution was 1.5 times the mass of the surface modification solution; The surface modification solution is prepared by compounding 55 parts by mass of 8 wt% polyvinyl alcohol solution and 25 parts by mass of modified polyethyleneimine solution; Compared with Example 2, Comparative Example 2 does not introduce the modified chitosan solution, and other steps are the same as those in Example 2.

[0033] Comparative Example 3: A method for preparing a high-strength ePTFE skeleton microporous membrane, comprising the following processes: The preparation method of modified chitosan solution is as follows: 80 parts of 0.1 mol / L MES buffer solution and 1 part of L-cysteine ​​were mixed evenly, 0.8 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 1.1 parts of N-hydroxysuccinimide were added, and the mixture was reacted in the dark for 35 minutes. 0.4 parts of chitosan was added, the pH was adjusted to 7.4, and the mixture was reacted for 20 hours to obtain a modified chitosan solution; Compared with Example 2, in Comparative Example 3, the modified L-cysteine ​​was replaced with L-cysteine ​​of the same mass, and the other steps were the same as those in Example 2.

[0034] Comparative Example 4: A method for preparing a high-strength ePTFE skeleton microporous membrane, comprising the following processes: Step S1: 100 parts of polytetrafluoroethylene resin and 20 parts of isododecane are mixed evenly, left to stand for aging, extruded into sheets, and dried and degreased (temperature 200°C, time 10 minutes) to obtain a polytetrafluoroethylene film; Step S2: longitudinally stretching the polytetrafluoroethylene film at a stretching temperature of 200° C., a stretching ratio of 600%, and a stretching distance of 150 mm; then transversely stretching the longitudinally stretched polytetrafluoroethylene film at a stretching temperature of 40° C., a stretching ratio of 200%, and heat setting to obtain an ePTFE skeleton microporous membrane; Step S3: The ePTFE skeleton microporous membrane was subjected to plasma surface activation treatment (air atmosphere, RF power of 50 W, treatment time of 5 minutes), immersed in a surface modification solution for 20 minutes (solid-to-liquid ratio of 1:18), and then added with a 3wt% glutaraldehyde solution to react for 1.5 hours. After washing and drying, a high-strength ePTFE skeleton microporous membrane was obtained; the amount of glutaraldehyde solution used was 1.5 times the mass of the surface modification solution; Compared with Example 2, the surface modification solution of Comparative Example 4 is prepared by compounding 55 parts by mass of 8 wt % polyvinyl alcohol solution, 25 parts by mass of modified polyethyleneimine solution, and 5 parts of modified chitosan solution; the other steps are the same as those in Example 2.

[0035] Experiment: The high-strength ePTFE skeleton microporous membranes obtained in Examples 1-3 and Comparative Examples 1-4 were used to prepare samples, and their properties were tested and the test results were recorded: The sterilized sample was placed in a culture dish, 200 μL of E. coli solution with a concentration of 10 6 CFU / mL was added dropwise, and the sample was placed in a 37°C constant temperature incubator for 18 h, after which the bacteriostatic rate was tested; the mechanical properties of the sample were tested according to GB / T1040 as a reference standard; the water contact angle was measured using a contact angle measuring instrument, and the volume of deionized water was 2 μL.

[0036] The test results are shown in Table 1.

[0037] Table 1: Performance test results of high-strength ePTFE skeleton microporous membrane

[0038] According to the data in the above table, the following conclusions can be clearly obtained: In combination with Examples 1-3 and Comparative Examples 1-4, it can be seen that the high-strength ePTFE skeleton microporous membrane prepared in the present application has excellent antibacterial rate, mechanical properties and hydrophilicity; in Comparative Example 1, antibacterial chlorogenic acid and graphene oxide were not introduced to modify the polyethyleneimine solution, and the antibacterial rate and mechanical properties of the material decreased; in Comparative Example 2, modified chitosan solution was not introduced, and the antibacterial properties and hydrophilicity of the obtained product decreased significantly; in Comparative Example 3, modified L-cysteine was replaced by L-cysteine, and the properties of the material decreased; it can be seen that the hydrophilicity of L-cysteine is modified by introducing organosilicon-modified allyl polyether; in Comparative Example 4, the antibacterial rate, tensile strength and hydrophilicity of the obtained product decreased; it can be seen that when the amount of modified chitosan solution is reduced, the properties of the material will decrease.

[0039] It will be obvious to a person skilled in the art that the application is not limited to the details of the foregoing exemplary embodiments, and that the application can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered to be exemplary and non-limiting, and the scope of the application is defined by the appended claims rather than the foregoing description, and all changes falling within the meaning and range of equivalent elements of the claims are intended to be encompassed by the application.

Claims

1. A method for preparing a high-strength ePTFE skeleton microporous membrane, characterized in that: The steps include: Step S1: uniformly mixing polytetrafluoroethylene resin and isododecane, allowing to stand for aging, extruding into sheets, and drying and degreasing to obtain a polytetrafluoroethylene film; Step S2: stretching the polytetrafluoroethylene film and heat-setting it to obtain an ePTFE skeleton microporous membrane; Step S3: The ePTFE skeleton microporous membrane is subjected to plasma surface activation treatment, immersed in a surface modification solution for 15-25 minutes, and then added with glutaraldehyde solution for reaction for 1-2 hours. After washing and drying, a high-strength ePTFE skeleton microporous membrane is obtained.

2. The method for preparing a high-strength ePTFE skeleton microporous membrane according to claim 1, wherein: The mass ratio of the polytetrafluoroethylene to isomeric dodecane is 10:(1-3).

3. The method for preparing a high-strength ePTFE skeleton microporous membrane according to claim 1, wherein: The atmosphere of the plasma surface activation treatment is air, the radio frequency power is 20-140W, and the treatment time is 1-10 minutes.

4. The method for preparing a high-strength ePTFE skeleton microporous membrane according to claim 1, wherein: The surface modification solution is prepared by compounding 50-60 parts by mass of polyvinyl alcohol solution, 20-30 parts by mass of modified polyethyleneimine solution, and 10-20 parts by mass of modified chitosan solution.

5. The method for preparing a high-strength ePTFE skeleton microporous membrane according to claim 4, characterized in that: The concentration of the polyvinyl alcohol solution is 5-10 wt %.

6. The method for preparing a high-strength ePTFE skeleton microporous membrane according to claim 4, characterized in that: The preparation method of the modified polyethyleneimine solution is as follows: The polyethyleneimine and phosphate buffer were mixed evenly, the pH of the system was adjusted to 5.0-5.5 using nitric acid, chlorogenic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were added, and the reaction was carried out for 2-3 hours. A mixed solution of graphene oxide and deionized water was added dropwise for 1-2 hours, and the mixture was reacted for 6-8 hours to obtain a modified polyethyleneimine solution.

7. The method for preparing a high-strength ePTFE skeleton microporous membrane according to claim 6, characterized in that: The mass ratio of the polyethyleneimine, phosphate buffer, chlorogenic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide is 1:(15-20):(0.5-0.7):(0.9-1.0), and the concentration of nitric acid is 1M.

8. The method for preparing a high-strength ePTFE skeleton microporous membrane according to claim 4, characterized in that: The preparation method of the modified chitosan solution is as follows: Step A: Evenly mix the epoxy-terminated allyl polyether and 3-aminopropyltriethoxysilane, and react at 40-60° C. for 5-7 hours to obtain a silicone-modified allyl polyether; Step B: uniformly mixing organosilicon-modified allyl polyether, L-cysteine ​​and ethanol, adding a photoinitiator, and irradiating with ultraviolet light to obtain modified L-cysteine; Step C: Mix the MES buffer solution and modified L-cysteine ​​evenly, add 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide, react in the dark for 30-40 minutes, add chitosan, adjust the pH to 7-7.5, and react for 12-24 hours to obtain a modified chitosan solution.

9. The method for preparing a high-strength ePTFE skeleton microporous membrane according to claim 8, characterized in that: The mass ratio of the modified L-cysteine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide and chitosan is 1:(0.7-0.9):(1.0-1.2):(0.3-0.5).

10. A high-strength ePTFE skeleton microporous membrane prepared according to the preparation method according to any one of claims 1 to 9.

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