A gradient porosity pmp composite membrane
By using a PMP/PVDF blend system and a gradient electrospinning process to prepare PMP membranes with gradient pore structures, the problems of complex preparation and insufficient performance of traditional PMP membrane materials are solved. This results in improved high-efficiency gas exchange and anti-plasma leakage performance, meeting the long-term use requirements of ECMO systems.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING TECH UNIV
- Filing Date
- 2025-05-15
- Publication Date
- 2026-05-15
AI Technical Summary
Existing PMP artificial lung membrane materials suffer from complex manufacturing processes, insufficient mechanical properties, and simple pore structures, resulting in low gas exchange efficiency, poor resistance to plasma leakage, and difficulty in meeting the stability requirements for long-term use.
A PMP/PVDF blend system and gradient electrospinning process were used to prepare a PMP membrane with a gradient pore structure at room temperature. Multi-walled carbon nanotubes were combined to improve mechanical strength, forming a three-layer structure of a dense skin and a porous support layer.
It achieves improved high-efficiency gas exchange performance and anti-plasma leakage performance, with tensile strength reaching 15-25 MPa, oxygen flux ≥2.0 mL/(min·cm²·bar), membrane hemolysis rate ≤5%, and good long-term stability.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of artificial lung oxygenators, specifically providing a poly(4-methyl-1-pentene) gas exchange membrane with a gradient pore structure and its preparation method. The PMP membrane is constructed with an asymmetric structure using electrospinning technology, comprising a dense cortex and a porous support layer, exhibiting high gas permeability, excellent resistance to plasma leakage, and long-term stability, making it suitable for extracorporeal membrane oxygenation (ECMO) systems. Background Technology
[0002] Extracorporeal membrane oxygenation (ECMO) is a key technology for treating severe respiratory failure. Its core functions are (1) oxygen delivery: when blood flows through the oxygenator, the extracorporeal oxygen partial pressure (P) increases. O2 (1) Oxygen in a mixture of gases (usually O2 / air) diffuses through the fiber membrane to the blood side with lower oxygen partial pressure; (2) Carbon dioxide removal: high partial pressure (P) in the blood CO2 The carbon dioxide diffuses back into the external gaseous environment. The membrane must simultaneously meet the following requirements:
[0003] (1) Highly efficient gas exchange: Rapid exchange of CO2 and O2 in the blood is achieved through diffusion;
[0004] (2) Anti-plasma leakage: Prevents plasma from osmosis that could cause membrane pore blockage or a decrease in gas exchange efficiency;
[0005] (3) Mechanical strength and biocompatibility: Ensure structural stability and blood compatibility during long-term cyclic use.
[0006] Traditional membrane materials have certain limitations. For example, polypropylene (PP) has low gas exchange efficiency, insufficient mechanical strength (tensile strength <10 MPa), and is prone to plasma leakage with long-term use. Although traditional PMP membranes have excellent gas permeability, existing preparation methods (such as thermally induced phase separation and melt spinning) have the following problems: complex processes, such as the thermally induced phase separation method used in CN202210434903.5, which requires high-temperature treatment (>200 ℃), resulting in high energy consumption and easy material degradation; and insufficient porosity, such as the PMP membrane described in CN202410823679.8, which has a porosity of only 45% to 65%, limiting gas diffusion efficiency.
[0007] Polyvinylidene fluoride (PVDF) is an ideal material for enhancing the structural stability of PMP membranes due to its excellent chemical stability (resistance to strong acids, strong alkalis, and biocorrosion). Furthermore, its gradient pore structure optimizes gas exchange efficiency and blood compatibility. This invention solves the performance imbalance problem of traditional membrane materials by innovatively combining a PMP / PVDF blend system with a gradient electrospinning process, providing a highly efficient method for preparing PMP membranes that possess both high oxygen permeability and a gradient pore structure. Summary of the Invention
[0008] To address the technical shortcomings of existing PMP artificial lung membranes, such as complex preparation processes, insufficient mechanical properties, and simple pore structures, this invention provides a novel PMP membrane with a gradient pore structure and its preparation method, the specific steps of which are as follows:
[0009] (1) Preparation of PMP-PVDF polymer blend solution
[0010] Poly(4-methyl-1-pentene) and polyvinylidene fluoride are mixed at a mass ratio of 1-5:1 and dissolved in a ternary mixed solvent of cyclohexane, N,N-dimethylformamide and acetone to form a homogeneous solution.
[0011] (2) Preparation of PMP membrane casting solution
[0012] Multi-walled carbon nanotubes and a dispersant are added to the PMP-PVDF polymer blend solution. The amount of multi-walled carbon nanotubes added is 0.01-2% of the total mass of the casting solution. The mixture is stirred until fully dispersed to obtain the casting solution.
[0013] (3) Electrospinning to prepare gradient pore structure PMP membranes
[0014] The ratio of PMP and PVDF was adjusted to different batches, and steps (1) and (2) were repeated to obtain different batches of casting solution. The PMP membrane with a three-layer structure was formed by electrospinning. The electrospinning parameters included: voltage 10-25kV, spinning rate 1.2 mL / h, and distance between nozzle and collector 10-20 cm. After spinning, the PMP membrane was peeled off from the receiving substrate and dried to obtain a PMP membrane with a gradient pore structure.
[0015] Preferably, step (1) is composed of cyclohexane, N,N-dimethylformamide and acetone in a mass ratio of 2-5:1-2:3-5.
[0016] Preferably, the PMP membrane in step (2) is composed of a blend of poly(4-methyl-1-pentene) and polyvinylidene fluoride, and multi-walled carbon nanotubes are added to improve mechanical strength, and its porosity varies in a gradient along the membrane thickness direction.
[0017] Preferably, in step (3), one side of the PMP membrane with a gradient pore structure is a dense layer to reduce the risk of plasma leakage, and the other side is a porous layer to enhance gas diffusion.
[0018] Preferably, the tensile strength of the PMP membrane with gradient pore structure in step (3) is 15-25 MPa, and the gas flux is 2.0-10.0 mL / (min·cm²·bar).
[0019] This invention provides a simpler and more controllable electrospinning technology compared to traditional melt spinning and thermally induced phase inversion methods. The electrospinning film-forming mechanism involves a polymer solution forming a Taylor cone at the nozzle under a high-voltage electric field, generating a charged jet stream. As the jet stream travels towards the receiving device, the solvent rapidly evaporates or the melt cools and solidifies, ultimately forming fibers that deposit on the receiving device to form a film.
[0020] Beneficial effects
[0021] Compared with the prior art, the present invention has significant advantages:
[0022] 1. Process optimization
[0023] By using a PMP / PVDF blend system combined with a ternary mixed solvent (cyclohexane / DMF / acetone), PMP can be dissolved at room temperature, avoiding material degradation caused by traditional high-temperature processing and reducing energy consumption.
[0024] 2. Precise control of gradient pore structure
[0025] A gradient pore distribution along the membrane thickness direction is achieved through a multi-stage electrospinning process, which balances high gas permeability and anti-plasma leakage performance.
[0026] 3. Significantly improved mechanical properties
[0027] The introduction of PVDF and multi-walled carbon nanotubes increases the tensile strength of the PMP membrane to 15~25 MPa, meeting the requirements for long-term cyclic use of ECMO.
[0028] 4. Long-term operational stability
[0029] This patented method prepares PMP composite nanofiber membranes that exhibit antibacterial properties, long-term operational stability, and corrosion resistance. Polyvinylpyrrolidone (PVP) not only acts as a dispersant but also imparts hydrophilicity to the membrane surface, effectively preventing plasma coagulation and ensuring long-term membrane stability. Oxygen flux is ≥2.0 mL / (min·cm²·bar), and membrane hemolysis rate is ≤5%. Attached Figure Description
[0030] Figure 1 Schematic diagram of gas exchange process in gradient pore PMP membrane
[0031] Figure 2 The water contact angles of each layer of the PMP membrane with gradient pore structure in Example 3 are: (a) porous layer; (b) transition layer; (c) dense layer. Detailed Implementation
[0032] The present invention will be further described below with reference to specific embodiments.
[0033] Example 1:
[0034] (1) Preparation of PMP-PVDF polymer blend solution
[0035] Add a stir bar to a reagent bottle, add 0.60 g of poly(4-methyl-1-pentene) and 0.60 g of polyvinylidene fluoride to the reagent bottle, and then slowly add 8.7 g of ternary mixed solvent. Heat to 50 °C and stir continuously for 4 h in the absence of air, with a stirring speed of 260 r / min, to make it mix evenly and form a homogeneous solution, thus obtaining the PMP-PVDF polymer blend solution.
[0036] (2) Preparation of PMP membrane casting solution
[0037] Add 0.05 g of polyvinylpyrrolidone to the above PMP-PVDF polymer blend solution and keep heating and stirring for 2 h. After the mixture is evenly dispersed, add 0.05 g of multi-walled carbon nanotubes to the above mixed solution. After ultrasonic treatment for 30 min, a uniformly dispersed solution is formed. Continue to heat and stir at 50 ℃ for 12 h, with a stirring speed of 260 r / min, to obtain the casting solution.
[0038] (3) Electrospinning to prepare gradient pore structure PMP membranes
[0039] The ratios of PMP and PVDF were adjusted to different ratios (PMP:PVDF = 1.0:1.0, 1.3:1.1, 7.0:5.0) in batches, and steps (1) and (2) were repeated to obtain different batches of casting solution. The PMP-PVDF polymer content in the casting solution was 12%. Electrospinning was used to spin the solution sequentially to form a PMP membrane with a three-layer structure. The aluminum foil was flattened and fixed on the roller of the electrospinning machine. The casting solution prepared in (2) was added to the syringe. The electrospinning machine was connected and the injection pump spinning parameters were set. The spinning volume was 6 mL and the spinning rate was 1.2 mL / h. The injection pump was pushed to the bottom of the syringe so that the casting solution just flowed out slightly from the syringe needle. Voltage was applied to the needle to make the casting solution filamentous. Electrospinning was performed for 5 h. After spinning was completed, the PMP membrane was peeled off from the receiving substrate and dried to obtain a PMP membrane with a gradient pore structure.
[0040] The performance of the PMP nanofiber membrane prepared in Example 1 was tested. The membrane had an oxygen flux of 4.68 mL / (min·cm²·bar), a hemolysis rate of 3.6%, a porosity of 60%, and a tensile strength of 18 MPa. The performance of the PMP nanofiber membrane remained at 96% even after 48 hours of continuous testing.
[0041] Example 2:
[0042] (1) Preparation of PMP-PVDF polymer blend solution
[0043] Add a stir bar to a reagent bottle, add 0.65 g of poly(4-methyl-1-pentene) and 0.55 g of polyvinylidene fluoride to the reagent bottle, and then slowly add 8.7 g of ternary mixed solvent. Heat to 50 °C and stir continuously for 4 h in the absence of air, with a stirring speed of 260 r / min, to make it mix evenly and form a homogeneous solution, thus obtaining the PMP-PVDF polymer blend solution.
[0044] (2) Preparation of PMP membrane casting solution
[0045] Add 0.05 g of polyvinylpyrrolidone to the above PMP-PVDF polymer blend solution and keep heating and stirring for 2 h. After the mixture is evenly dispersed, add 0.05 g of multi-walled carbon nanotubes to the above mixed solution. After ultrasonic treatment for 30 min, a uniformly dispersed solution is formed. Continue to heat and stir at 50 ℃ for 12 h, with a stirring speed of 260 r / min, to obtain the casting solution.
[0046] (3) Electrospinning to prepare gradient pore structure PMP membranes
[0047] The ratios of PMP and PVDF were adjusted to different ratios (PMP:PVDF = 1.3:1.1, 7.0:5.0, 5.0:3.0) in batches, and steps (1) and (2) were repeated to obtain different batches of casting solution. The PMP-PVDF polymer content in the casting solution was 12%. Electrospinning was used to spin the solution sequentially to form a PMP membrane with a three-layer structure. The aluminum foil was flattened and fixed on the roller of the electrospinning machine. The casting solution prepared in (2) was added to the syringe. The electrospinning machine was connected and the injection pump spinning parameters were set. The spinning volume was 6 mL and the spinning rate was 1.2 mL / h. The injection pump was pushed to the bottom of the syringe so that the casting solution just flowed out slightly from the syringe needle. Voltage was applied to the needle to make the casting solution filamentous. Electrospinning was performed for 5 h. After spinning was completed, the PMP membrane was peeled off from the receiving substrate and dried to obtain a PMP membrane with a gradient pore structure.
[0048] The performance of the PMP nanofiber membrane prepared in Example 2 was tested. The oxygen flux of the membrane was 5.23 mL / (min·cm²·bar), the hemolysis rate was 3.9%, the porosity was 64%, and the tensile strength was 20 MPa. The performance of the PMP nanofiber membrane could still reach 95% after 48 hours of continuous testing.
[0049] Example 3:
[0050] (1) Preparation of PMP-PVDF polymer blend solution
[0051] Add a stir bar to a reagent bottle, add 0.70 g of poly(4-methyl-1-pentene) and 0.50 g of polyvinylidene fluoride to the reagent bottle, and then slowly add 8.7 g of ternary mixed solvent. Heat to 50 °C and stir continuously for 4 h in the absence of air, with a stirring speed of 260 r / min, to make it mix evenly and form a homogeneous solution, thus obtaining the PMP-PVDF polymer blend solution.
[0052] (2) Preparation of PMP membrane casting solution
[0053] Add 0.04 g of polyvinylpyrrolidone to the above PMP-PVDF polymer blend solution and keep heating and stirring for 2 h. After the mixture is evenly dispersed, add 0.06 g of multi-walled carbon nanotubes to the above mixed solution. After ultrasonic treatment for 30 min, a uniformly dispersed solution is formed. Continue to heat and stir at 50 ℃ for 12 h, with a stirring speed of 260 r / min, to obtain the casting solution.
[0054] (3) Electrospinning to prepare gradient pore structure PMP membranes
[0055] The ratios of PMP and PVDF were adjusted to different ratios (PMP:PVDF = 7.0:5.0, 5.0:3.0, 2.0:1.0) in batches, and steps (1) and (2) were repeated to obtain different batches of casting solution. The PMP-PVDF polymer content in the casting solution was 12%. Electrospinning was used to spin the solution sequentially to form a PMP membrane with a three-layer structure. The aluminum foil was flattened and fixed on the roller of the electrospinning machine. The casting solution prepared in (2) was added to the syringe. The electrospinning machine was connected and the injection pump spinning parameters were set. The spinning volume was 6 mL and the spinning rate was 1.2 mL / h. The injection pump was pushed to the bottom of the syringe so that the casting solution just flowed out slightly from the syringe needle. Voltage was applied to the needle so that the casting solution became filamentous. Electrospinning was performed for 5 h. After spinning was completed, the PMP membrane was peeled off from the receiving substrate and dried to obtain a PMP membrane with a gradient pore structure.
[0056] The performance of the PMP nanofiber membrane prepared in Example 3 was tested. The oxygen flux of the membrane was 6.15 mL / (min·cm²·bar), the hemolysis rate was 3.7%, the porosity was 66%, and the tensile strength was 24 MPa. The performance of the PMP nanofiber membrane could still reach 95% after 48 hours of continuous testing.
[0057] Example 4:
[0058] (1) Preparation of PMP-PVDF polymer blend solution
[0059] Add a stir bar to a reagent bottle, add 0.75 g of poly(4-methyl-1-pentene) and 0.45 g of polyvinylidene fluoride to the reagent bottle, and then slowly add 8.7 g of ternary mixed solvent. Heat to 50 °C and stir continuously for 4 h in the absence of air, with a stirring speed of 260 r / min, to make it mix evenly and form a homogeneous solution, thus obtaining the PMP-PVDF polymer blend solution.
[0060] (2) Preparation of PMP membrane casting solution
[0061] Add 0.05 g of polyvinylpyrrolidone to the above PMP-PVDF polymer blend solution and keep heating and stirring for 2 h. After the mixture is evenly dispersed, add 0.05 g of multi-walled carbon nanotubes to the above mixed solution. After ultrasonic treatment for 30 min, a uniformly dispersed solution is formed. Continue to heat and stir at 50 ℃ for 12 h, with a stirring speed of 260 r / min, to obtain the casting solution.
[0062] (3) Electrospinning to prepare gradient pore structure PMP membranes
[0063] The ratios of PMP and PVDF were adjusted to different ratios (PMP:PVDF = 5.0:3.0, 2.0:1.0, 1.7:0.7) in batches, and steps (1) and (2) were repeated to obtain different batches of casting solution. The PMP-PVDF polymer content in the casting solution was 12%. Electrospinning was used to spin the solution sequentially to form a PMP membrane with a three-layer structure. The aluminum foil was flattened and fixed on the roller of the electrospinning machine. The casting solution prepared in (2) was added to the syringe. The electrospinning machine was connected and the injection pump spinning parameters were set. The spinning volume was 6 mL and the spinning rate was 1.2 mL / h. The injection pump was pushed to the bottom of the syringe so that the casting solution just flowed out slightly from the syringe needle. Voltage was applied to the needle to make the casting solution filamentous. Electrospinning was performed for 5 h. After spinning was completed, the PMP membrane was peeled off from the receiving substrate and dried to obtain a PMP membrane with a gradient pore structure.
[0064] The performance of the PMP nanofiber membrane prepared in Example 4 was tested. The membrane had an oxygen flux of 5.61 mL / (min·cm²·bar), a hemolysis rate of 3.1%, a porosity of 68%, and a tensile strength of 21 MPa. The performance of the PMP nanofiber membrane remained at 94% even after 48 hours of continuous testing.
[0065] Example 5:
[0066] (1) Preparation of PMP-PVDF polymer blend solution
[0067] Add a stir bar to a reagent bottle, add 0.80 g of poly(4-methyl-1-pentene) and 0.40 g of polyvinylidene fluoride to the reagent bottle, and then slowly add 8.7 g of ternary mixed solvent. Heat to 50 °C and stir continuously for 4 h in the absence of air, with a stirring speed of 260 r / min, to make it mix evenly and form a homogeneous solution, thus obtaining the PMP-PVDF polymer blend solution.
[0068] (2) Preparation of PMP membrane casting solution
[0069] Add 0.05 g of polyvinylpyrrolidone to the above PMP-PVDF polymer blend solution and keep heating and stirring for 2 h. After the mixture is evenly dispersed, add 0.05 g of multi-walled carbon nanotubes to the above mixed solution. After ultrasonic treatment for 30 min, a uniformly dispersed solution is formed. Continue to heat and stir at 50 ℃ for 12 h, with a stirring speed of 260 r / min, to obtain the casting solution.
[0070] (3) Electrospinning to prepare gradient pore structure PMP membranes
[0071] The ratios of PMP and PVDF were adjusted to different ratios (PMP:PVDF = 2.0:1.0, 1.7:0.7, 3.0:1.0) in batches, and steps (1) and (2) were repeated to obtain different batches of casting solution. The PMP-PVDF polymer content in the casting solution was 12%. Electrospinning was used to spin the solution sequentially to form a PMP membrane with a three-layer structure. The aluminum foil was flattened and fixed on the roller of the electrospinning machine. The casting solution prepared in (2) was added to the syringe. The electrospinning machine was connected and the injection pump spinning parameters were set. The spinning volume was 6 mL and the spinning rate was 1.2 mL / h. The injection pump was pushed to the bottom of the syringe so that the casting solution just flowed out slightly from the syringe needle. Voltage was applied to the needle to make the casting solution filamentous. Electrospinning was performed for 5 h. After spinning was completed, the PMP membrane was peeled off from the receiving substrate and dried to obtain a PMP membrane with a gradient pore structure.
[0072] The performance of the PMP nanofiber membrane prepared in Example 5 was tested. The oxygen flux of the membrane was 5.41 mL / (min·cm²·bar), the hemolysis rate was 2.8%, the porosity was 72%, and the tensile strength was 24 MPa. The performance of the PMP nanofiber membrane could still reach 98% after 48 hours of continuous experiment.
[0073] Example 6:
[0074] (1) Preparation of PMP-PVDF polymer blend solution
[0075] Add a stir bar to a reagent bottle, add 0.85 g of poly(4-methyl-1-pentene) and 0.35 g of polyvinylidene fluoride to the reagent bottle, and then slowly add 8.7 g of ternary mixed solvent. Heat to 50 °C and stir continuously for 4 h in the absence of air, with a stirring speed of 260 r / min, to make it mix evenly and form a homogeneous solution, thus obtaining the PMP-PVDF polymer blend solution.
[0076] (2) Preparation of PMP membrane casting solution
[0077] Add 0.05 g of polyvinylpyrrolidone to the above PMP-PVDF polymer blend solution and keep heating and stirring for 2 h. After the mixture is evenly dispersed, add 0.05 g of multi-walled carbon nanotubes to the above mixed solution. After ultrasonic treatment for 30 min, a uniformly dispersed solution is formed. Continue to heat and stir at 50 ℃ for 12 h, with a stirring speed of 260 r / min, to obtain the casting solution.
[0078] (3) Electrospinning to prepare gradient pore structure PMP membranes
[0079] The ratios of PMP and PVDF were adjusted to different ratios (PMP:PVDF = 1.7:0.7, 3.0:1.0, 4.0:1.0) in batches, and steps (1) and (2) were repeated to obtain different batches of casting solution. The PMP-PVDF polymer content in the casting solution was 12%. Electrospinning was used to spin the solution sequentially to form a PMP membrane with a three-layer structure. The aluminum foil was flattened and fixed on the roller of the electrospinning machine. The casting solution prepared in (2) was added to the syringe. The electrospinning machine was connected and the injection pump spinning parameters were set. The spinning volume was 6 mL and the spinning rate was 1.2 mL / h. The injection pump was pushed to the bottom of the syringe so that the casting solution just flowed out slightly from the syringe needle. Voltage was applied to the needle to make the casting solution filamentous. Electrospinning was performed for 5 h. After spinning was completed, the PMP membrane was peeled off from the receiving substrate and dried to obtain a PMP membrane with a gradient pore structure.
[0080] The performance of the PMP nanofiber membrane prepared in Example 6 was tested. The membrane had an oxygen flux of 5.27 mL / (min·cm²·bar), a hemolysis rate of 3.5%, a porosity of 71%, and a tensile strength of 26 MPa. The performance of the PMP nanofiber membrane remained at 97% even after 48 hours of continuous testing.
[0081] Example 7:
[0082] (1) Preparation of PMP-PVDF polymer blend solution
[0083] Add a stir bar to a reagent bottle, add 0.90 g of poly(4-methyl-1-pentene) and 0.30 g of polyvinylidene fluoride to the reagent bottle, and then slowly add 8.7 g of ternary mixed solvent. Heat to 50 °C and stir continuously for 4 h in the absence of air, with a stirring speed of 260 r / min, to make it mix evenly and form a homogeneous solution, thus obtaining the PMP-PVDF polymer blend solution.
[0084] (2) Preparation of PMP membrane casting solution
[0085] Add 0.05 g of polyvinylpyrrolidone to the above PMP-PVDF polymer blend solution and keep heating and stirring for 2 h. After the mixture is evenly dispersed, add 0.05 g of multi-walled carbon nanotubes to the above mixed solution. After ultrasonic treatment for 30 min, a uniformly dispersed solution is formed. Continue to heat and stir at 50 ℃ for 12 h, with a stirring speed of 260 r / min, to obtain the casting solution.
[0086] (3) Electrospinning to prepare gradient pore structure PMP membranes
[0087] The ratios of PMP and PVDF were adjusted to different ratios (PMP:PVDF = 3.0:1.0, 4.0:1.0, 5.0:1.0) in batches, and steps (1) and (2) were repeated to obtain different batches of casting solution. The PMP-PVDF polymer content in the casting solution was 12%. Electrospinning was used to spin the solution sequentially to form a PMP membrane with a three-layer structure. The aluminum foil was flattened and fixed on the roller of the electrospinning machine. The casting solution prepared in (2) was added to the syringe. The electrospinning machine was connected and the injection pump spinning parameters were set. The spinning volume was 6 mL and the spinning rate was 1.2 mL / h. The injection pump was pushed to the bottom of the syringe so that the casting solution just flowed out slightly from the syringe needle. Voltage was applied to the needle to make the casting solution filamentous. Electrospinning was performed for 5 h. After spinning was completed, the PMP membrane was peeled off from the receiving substrate and dried to obtain a PMP membrane with a gradient pore structure.
[0088] The performance of the PMP nanofiber membrane prepared in Example 7 was tested. The membrane had an oxygen flux of 4.78 mL / (min·cm²·bar), a hemolysis rate of 3.3%, a porosity of 72%, and a tensile strength of 27 MPa. The performance of the PMP nanofiber membrane remained at 97% even after 48 hours of continuous testing.
Claims
1. A method for preparing a gradient pore structure PMP membrane, characterized in that, Includes the following steps: (1) Preparation of PMP-PVDF polymer blend solution Poly(4-methyl-1-pentene) and polyvinylidene fluoride are mixed at a mass ratio of 1-5:1 and dissolved in a ternary mixed solvent of cyclohexane, N,N-dimethylformamide and acetone to form a homogeneous solution. The mass ratio of cyclohexane, N,N-dimethylformamide and acetone in the ternary mixed solvent is 2-5:1-2:3-5. (2) Preparation of PMP membrane casting solution Multi-walled carbon nanotubes and a dispersant were added to the PMP-PVDF polymer blend solution. The amount of multi-walled carbon nanotubes added was 0.01-2% of the total mass of the casting solution. The mixture was stirred until fully dispersed to obtain the casting solution. The dispersant was polyvinylpyrrolidone. (3) Electrospinning to prepare gradient pore structure PMP membranes The PMP and PVDF ratios were adjusted to different ratios in three batches, and steps (1) and (2) were repeated to obtain three batches of different casting solutions. The solutions were then spun sequentially using an electrospinning process to form a PMP membrane with a three-layer structure. The electrospinning parameters included: voltage 10-25kV, spinning rate 1.2 mL / h, and distance between the nozzle and the collector 10-20 cm. After spinning, the PMP membrane was peeled off from the receiving substrate and dried to obtain a PMP membrane with a gradient pore structure.
2. The preparation method according to claim 1, characterized in that, The PMP membrane is composed of a blend of poly(4-methyl-1-pentene) and polyvinylidene fluoride, with the addition of multi-walled carbon nanotubes to improve mechanical strength. Its porosity varies in a gradient along the membrane thickness direction.
3. The preparation method according to claim 1, characterized in that, One side of the PMP membrane is a dense layer to reduce the risk of plasma leakage, and the other side is a porous layer to enhance gas diffusion.
4. The preparation method according to claim 1, characterized in that, The PMP membrane has a tensile strength of 15-25 MPa and a gas flux of 2.0-10.0 mL / (min·cm²·bar).