Hybrid flat sheet membranes of poly(4-methyl-1-pentene) / three-dimensional covalent organic frameworks and methods of making and using the same

Abstract

The application provides a hybrid flat membrane of poly-4-methyl-1-pentene / three-dimensional covalent organic framework and a preparation method and application thereof. The method comprises the following steps: weighing formula materials; preparing a casting solution of the hybrid membrane; and forming the hybrid flat membrane. The hybrid flat membrane has the characteristics of large specific surface area, high density of functional groups and high mechanical properties. The three-dimensional covalent organic framework is blended with poly-4-methyl-1-pentene, and a hybrid membrane is prepared by using a thermally induced phase separation method. The embedding of the three-dimensional covalent organic framework provides additional adsorption and transmission channels for oxygen and carbon dioxide, significantly improves the gas permeability of the hybrid flat membrane, the three-dimensional covalent organic framework and the poly-4-methyl-1-pentene molecular chain are intertwined, the mechanical properties of the hybrid flat membrane are improved, and meanwhile, the complex regulation and control of the membrane structure for improving the gas transmission performance and the mechanical properties of the poly-4-methyl-1-pentene hybrid flat membrane in the current production process is avoided.

Description

Technical Field

[0001] This invention belongs to the field of membrane technology, specifically relating to the application of a hybrid flat sheet membrane based on a three-dimensional covalent organic framework. Background Technology

[0002] Extracorporeal membrane oxygenation (ECMO) primarily involves exchanging oxygen and carbon dioxide from hypoxic venous blood in the extracorporeal circulation with pure oxygenated scavenging gas, thereby increasing oxygen saturation and removing carbon dioxide to allow arterial blood to enter the body. ECMO is used for acute respiratory distress syndrome, organ transplantation, and other cardiopulmonary surgeries or diseases. The membrane lung performs the function of blood gas transport, and the gas permeability, blood compatibility, mechanical properties, and resistance to plasma leakage of its key component, the oxygenation membrane, directly affect the performance of the oxygenator.

[0003] To ensure that venous blood meets the requirements of arterial blood, the carbon dioxide to oxygen mass transfer coefficient ratio of the oxygenation membrane must be greater than 12 (L / m). 2 While the mass transfer coefficient (CTL) is only 3-4 in clinical applications, at the highest scavenging flow rate within the safe range, the large amount of carbon dioxide removed from approximately 50% of ARDS patients is insufficient to prevent potential spontaneous breathing. Dyspnea persists, and the carbon dioxide delivery is insufficient to meet the respiratory needs of 90% of patients, easily leading to hypercapnia. Increasing the gas velocity to increase the mass transfer driving force can easily lead to serious consequences such as air embolism. Therefore, the development of high-performance oxygenation membranes with reasonable gas velocities is urgently needed. Among currently commercially available flat sheet membranes, poly(4-methyl-1-pentene) flat sheet membranes have the greatest advantages. Poly(4-methyl-1-pentene) flat sheet membranes have a porous cellular structure and a dense skin layer, exhibiting strong resistance to plasma leakage, but their gas permeability and mechanical properties are not ideal. Their production process, thermally induced phase separation (TIPS), has been thoroughly investigated, and the film formation process is relatively easy to control. Furthermore, the surface of poly(4-methyl-1-pentene) membranes only contains methyl and methylene groups, lacking active groups, posing a significant challenge to post-modification. Therefore, how to efficiently prepare and produce poly(4-methyl-1-pentene) oxygenation membranes with high gas transfer rates is crucial.

[0004] Currently, three-dimensional covalent organic frameworks (3GOCs) are developing rapidly. They possess large specific surface area, high-density functional groups, and high mechanical properties. They exhibit water stability, high thermal stability, solvent stability, and high mechanical properties, along with interconnected, uniform, connected, and stable regular mass transfer channels. They can be functionalized with carboxyl or hydroxyl groups and possess a tetrahedral configuration with multiple interlocking structures, making them widely used in separation systems. Their porous channels facilitate the permeation of oxygen and carbon dioxide, and polar groups can interact with polar carbon dioxide. Hybridizing 3GOCs with poly(4-methyl-1-pentene) provides additional channels for the rapid transport of oxygen and carbon dioxide, and the intertwining of their molecular chains improves the mechanical properties of the oxygenation membrane, achieving the goal of enhancing the clinical performance of hybrid flat sheet membranes.

[0005] Therefore, in view of the problems of unsatisfactory gas permeability and mechanical properties and difficulties in post-modification of currently commercially available flat sheet oxygen membranes, this invention prepares a hybrid membrane by physically blending a three-dimensional covalent organic framework with poly4-methyl-1-pentene and then using the TIPS method. This is expected to solve these problems and promote the development of the flat sheet oxygen membrane field. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a hybrid flat sheet membrane of poly(4-methyl-1-pentene) / three-dimensional covalent organic framework, its preparation method, and its applications. The polymer membrane material is poly(4-methyl-1-pentene) (PMP), the diluent is dioctyl phthalate, and the membrane preparation method is thermally induced phase separation (TIPS). By first ultrasonically dispersing the three-dimensional covalent organic framework and the diluent into a homogeneous solution, and then adding poly(4-methyl-1-pentene) (PMP) and heating and stirring, uniform dispersion of the three-dimensional covalent organic framework and poly(4-methyl-1-pentene) (PMP) can be achieved. This method is simple, efficient, and controllable in its preparation. The prepared oxygenated membrane has abundant transport channels and functional groups, which can effectively reduce gas transport resistance. Furthermore, the intertwining of the molecular chains of the two components improves the mechanical properties of the oxygenated membrane without significantly affecting the main membrane structure, thus significantly improving both the gas permeability and mechanical properties of the membrane.

[0007] Furthermore, the aforementioned planar membrane based on a hybrid of a three-dimensional covalent organic framework and poly-4-methyl-1-pentene is characterized in that the three-dimensional covalent organic framework is a porous covalent organic framework material with water stability, high thermal stability, solvent stability, and high mechanical properties. It possesses interconnected, uniform, connected, and stable regular mass transfer channels, can undergo carboxyl or hydroxyl functionalization, and has a tetrahedral configuration with multiple interlocking structures. During the preparation of this hybrid planar membrane, it is melt-blended with poly-4-methyl-1-pentene to form a homogeneous solution.

[0008] To address the aforementioned technical problems, this invention prepares a hybrid flat sheet membrane with high mechanical properties and oxygen and carbon dioxide permeation performance by physically blending a three-dimensional covalent organic framework with poly(4-methyl-1-pentene) and forming the membrane using TIPS.

[0009] The present invention relates to a hybrid planar membrane of poly(4-methyl-1-pentene) / three-dimensional covalent organic framework; characterized in that, as Figure 1 As shown in (a), the hybrid planar membrane is a planar membrane based on a three-dimensional covalent organic framework hybridized with poly(4-methyl-1-pentene). The thickness of the hybrid planar membrane is 255-434 μm, and the thickness of the compact layer is 0.64-0.86 μm; Figure 1 As shown in (a) and (b), the pore structure and distribution of the hybrid flat sheet membrane have been improved and modified. The dense layer is a non-porous, dense skin layer, and the porous layer is a bicontinuous, cellular, loose structure. Furthermore, the three-dimensional covalent organic framework and poly(4-methyl-1-pentene) are uniformly dispersed. In addition, the hybrid membrane prepared in this invention combines the advantages of poly(4-methyl-1-pentene) separation membranes with the adsorption characteristics of the three-dimensional covalent organic framework and the tetrahedral structure with multiple interlocking structures. The membrane exhibits stable physical properties, and its carbon dioxide and oxygen permeation performance, as well as its mechanical properties, are all improved to a certain extent.

[0010] The method for preparing the hybrid planar membrane of poly-4-methyl-1-pentene / three-dimensional covalent organic framework of the present invention includes the following steps:

[0011] (1) Weigh the formulation materials, including dioctyl phthalate as a diluent, poly(4-methyl-1-pentene) and three-dimensional covalent organic framework; the mass percentage of the materials in the formulation is: the mass ratio of poly(4-methyl-1-pentene) to dioctyl phthalate as a diluent is 1:9~4:6, and the mass percentage of the three-dimensional covalent organic framework is 0.5-5% of poly(4-methyl-1-pentene). First, ultrasonically disperse and cell-break the three-dimensional covalent organic framework and dioctyl phthalate as a diluent until they are uniformly dispersed, then add poly(4-methyl-1-pentene), heat and stir, and allow to stand to degas and prepare the hybrid membrane casting solution;

[0012] (2) The hybrid flat sheet membrane is formed by TIPS method. A scraper is selected to scrape the flat sheet membrane. The homogeneous casting liquid after scraping is introduced into a water coagulation bath at room temperature along with the glass plate to cause solid-liquid or liquid-liquid phase separation and solidification.

[0013] (3) Add the formed flat sheet membrane to the solvent, and replace the solvent every 8-12 hours. Extract by solvent exchange for 2-3 days.

[0014] (4) Place the flat sheet membrane obtained after extraction in step (3) in a room temperature oven to dry for 1-2 days.

[0015] Further, in step (1), the mass ratio of poly(4-methyl-1-pentene) to dioctyl phthalate (DAPI) is 1:9 to 4:6, and the mass percentage of the three-dimensional covalent organic framework is 0.5-5% of poly(4-methyl-1-pentene).

[0016] Further, in step (1), the three-dimensional covalent organic framework and the diluent dioctyl phthalate are ultrasonically treated for 10-30 minutes. After the three-dimensional covalent organic framework is evenly dispersed, it is then ultrasonically treated for cell disruption for 10-30 minutes, followed by the addition of poly4-methyl-1-pentene. The mixture is heated to 220-230°C and stirred for 6-12 hours to fully dissolve the poly4-methyl-1-pentene and prevent large crystallization and agglomeration. After stirring is stopped, the temperature is raised to 230-240°C and allowed to stand for 6-12 hours to remove bubbles, thus obtaining the casting solution.

[0017] Furthermore, in step (2), the distance between the scraper and the glass plate is 100-200μm, and the temperature of the heating table is set to 220-260℃.

[0018] Furthermore, in step (2), the thickness of the hybrid flat membrane is 255-550 μm, and the thickness of the dense layer is 0.64-0.86 μm. The dense layer is a non-porous and dense cortex, and the porous layer has a bicontinuous cellular loose structure in cross-section.

[0019] Furthermore, in step (3), the solvent is a solvent that is miscible with the diluent and water but insoluble in the polymer, such as one or more of anhydrous ethanol and isopropanol. The extraction process lasts for 2-3 days, with the solvent being changed every 8-12 hours.

[0020] Furthermore, in step (4), the oven temperature is 20-30℃.

[0021] The hybrid flat-sheet membrane based on the poly(4-methyl-1-pentene) / three-dimensional covalent organic framework provided by this invention is applied in the field of extracorporeal membrane oxygenation (ECMO). The membrane acts as a barrier for blood and gas exchange in the membrane lung, preventing direct contact between the two. To improve the mass transfer efficiency of blood-gas exchange per unit area, the membrane is typically encapsulated into membrane modules, including flat-sheet membrane modules and hollow fiber membrane modules. Applying this membrane to flat-sheet membrane modules effectively solves the problem of low gas transfer efficiency in flat-sheet membrane modules (carbon dioxide transfer capacity 18.00 mL / (min·cm²)). 2 • bar), oxygen transport capacity 25.74 mL / (min·cm 2 The challenge of achieving a CO2 / O2 exchange rate greater than 200 ml / min, while meeting the requirements of low pressure drop (to achieve a CO2 / DO2 ratio greater than 12:1 in clinical applications), low pre-charge volume (200-300 ml), and small device size (surface-to-volume ratio 3.76~111.11 cm³), is addressed.-1 Highly efficient gas transport.

[0022] The beneficial effects of this invention are explained as follows:

[0023] (1) This invention prepares a hybrid planar membrane by incorporating a three-dimensional covalent organic framework. Due to its high content of imine and benzene ring groups, high-density pores, and large specific surface area, the three-dimensional covalent organic framework can generate polar interactions with polar carbon dioxide, enhancing the dissolution-diffusion process of oxygen and carbon dioxide molecules through the membrane. Furthermore, the good interaction and compatibility between the three-dimensional covalent organic framework nanosheets and poly(4-methyl-1-pentene) increases the free volume of the membrane, reducing the resistance to gas transport within the membrane. The coordinated action of these multiple mechanisms results in a hybrid planar membrane with highly efficient gas transport performance. The PMP-3D-OH-COF-1.0 hybrid membrane exhibits the best oxygen and carbon dioxide gas permeability, with a carbon dioxide transport capacity of 31.96 mL / (min·cm). 2 (·bar), compared to the unhybridized poly4-methyl-1-pentene's carbon dioxide transport capacity of 18.00 mL / (min·cm). 2 In terms of oxygen transport capacity (in terms of bar), it increased by 77.55%; the oxygen transport capacity was 64.37 mL / (min·cm). 2 The oxygen transport capacity of poly(4-methyl-1-pentene) is 25.74 mL / (min·cm), compared to 25.74 mL / (min·cm). 2 For bar), it increased by 150.08%.

[0024] (2) The three-dimensional covalent organic framework can be functionalized with carboxyl and hydroxyl groups, and the three-dimensional covalent organic framework nanosheets have good interfacial compatibility with poly(4-methyl-1-pentene), avoiding the generation of defects and agglomeration. For the preparation process of poly(4-methyl-1-pentene) flat sheet membrane, the present invention reduces the difficulty of membrane preparation and simplifies the membrane preparation process by uniformly dispersing carboxylated or hydroxylated three-dimensional covalent organic frameworks in the casting solution and forming the membrane with TIPS. Furthermore, the intertwining of carboxylated or hydroxylated three-dimensional covalent organic frameworks and poly(4-methyl-1-pentene) molecular chains can improve the mechanical properties of the oxygenation membrane. The PMP-3D-OH-COF-1.0 hybrid membrane exhibits the best mechanical properties, with a tensile strength of 2.12 MPa, which is 12.76% higher than the 1.88 MPa of unhybridized poly(4-methyl-1-pentene); and an elongation at break of 570.9%, which is 14.11% higher than the 500.3% of unhybridized poly(4-methyl-1-pentene). The resulting hybrid flat sheet membrane is highly competitive. Attached Figure Description

[0025] Figure 1These are cross-sectional and surface views of the prepared poly(4-methyl-1-pentene) / three-dimensional covalent organic framework hybrid sheet membrane.

[0026] Figure 2 This is a comparison chart of the oxygen and carbon dioxide permeation rate performance of the membranes prepared by the methods in Examples 1-4 and the membrane prepared by the unmodified Comparative Example 1.

[0027] Figure 3 This is a comparison chart of the mechanical properties of the membranes prepared by the methods in Examples 1-4 and the membrane prepared by Comparative Example 1 without modification. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0029] (1) Weigh the materials according to the formula. The mass percentage of the materials in the formula is: the mass ratio of poly(4-methyl-1-pentene) to dioctyl phthalate is 1:9~4:6, and the mass percentage of the three-dimensional covalent organic framework is 0.5-5% of poly(4-methyl-1-pentene). First, add some materials, add the three-dimensional covalent organic framework material to dioctyl phthalate, and after ultrasonic dispersion and cell disruption, the three-dimensional covalent organic framework material is evenly dispersed by ultrasonic dispersion. Then add poly(4-methyl-1-pentene), heat to 220-230℃ and stir for 6-12h, then heat to 230-240℃ and let stand for 6-12h to remove bubbles to obtain a homogeneous casting solution.

[0030] (3) The hybrid flat sheet membrane is formed by TIPS method. A flat sheet membrane with a thickness of 100-200μm is selected. The homogeneous casting liquid after coating is introduced into a water coagulation bath at room temperature along with the glass plate to undergo solid-liquid or liquid-liquid phase separation and solidification.

[0031] (4) Add the formed flat sheet membrane to the solvent, and replace the solvent every 8-12 hours. Extract by solvent exchange for 2-3 days.

[0032] (5) Place the flat sheet membrane obtained after extraction in step (4) in a room temperature oven to dry for 1-2 days.

[0033] Example 1: Preparation of PMP-3D-OH-COF-0.5 hybrid flat sheet membrane

[0034] Material formulation:

[0035] The mass ratio of poly(4-methyl-1-pentene) to diluent is 1:9, and the mass of the three-dimensional covalent organic framework 3D-OH-COF is 0.5% of the mass of poly(4-methyl-1-pentene). Weigh the following proportions: for sheet membranes, weigh 18g of dioctyl phthalate, 10mg of the three-dimensional covalent organic framework 3D-OH-COF, and 2g of poly(4-methyl-1-pentene).

[0036] Preparation of casting solution for flat sheet membranes:

[0037] Dioctyl phthalate and the three-dimensional covalent organic framework 3D-OH-COF were weighed and added to a 50 mL three-necked flask. The mixture was sonicated for 10 min until the 3D-OH-COF was evenly dispersed, resulting in an orange-yellow suspension. Cell disruption was then achieved by sonicating the suspension for another 10 min. 2 g of poly-4-methyl-1-pentene was added to the suspension, and the mixture was stirred at 220 °C for 6 h. The stirred casting solution was then heated to 230 °C and allowed to stand for 6 h, ready for use in preparing a flat sheet membrane.

[0038] Preparation of planar hybrid films:

[0039] A quartz glass plate was placed on a heating plate at 220°C for 10 minutes. A casting solution at 240°C was poured onto one end of the glass plate, and quickly scraped to the other end using a spatula at a distance of 100 μm from the glass plate. The coated glass plate was then rapidly immersed in water to cool for 3 minutes. Next, the glass plate was extracted in ethanol or isopropanol for 1 hour. After the membrane automatically detached from the glass plate, it was extracted in fresh isopropanol or ethanol for two days, with the isopropanol or ethanol being replaced every 8 hours. Finally, the membrane was dried in a 20°C oven for one day.

[0040] Example 2: Preparation of PMP-3D-OH-COF-1.0 hybrid flat sheet membrane

[0041] Material formulation:

[0042] The mass ratio of poly(4-methyl-1-pentene) to diluent is 2:8, and the mass of the three-dimensional covalent organic framework 3D-OH-COF is 1.0% of the mass of poly(4-methyl-1-pentene). Weigh the following proportions: for sheet membranes, weigh 8g of dioctyl phthalate, 20mg of the three-dimensional covalent organic framework 3D-OH-COF, and 2g of poly(4-methyl-1-pentene).

[0043] Preparation of casting solution for flat sheet membranes:

[0044] Dioctyl phthalate and the three-dimensional covalent organic framework 3D-OH-COF were weighed and added to a 20 mL three-necked flask. The mixture was sonicated for 20 min until the 3D-OH-COF was evenly dispersed, resulting in an orange-yellow suspension. Cell disruption was then achieved by sonicating the suspension for another 20 min. 2 g of poly-4-methyl-1-pentene was added to the suspension, and the mixture was stirred at 225 °C for 9 h. The stirred casting solution was then heated to 235 °C and allowed to stand for 9 h, ready for use in preparing a flat sheet membrane.

[0045] Preparation of planar hybrid films:

[0046] A quartz glass plate was placed on a 240°C heating plate for 10 minutes. A casting solution at 240°C was poured onto one end of the glass plate, and quickly scraped to the other end using a spatula at a distance of 150 μm from the glass plate. The coated glass plate was then rapidly immersed in water to cool for 3 minutes. Next, the glass plate was extracted in anhydrous ethanol or isopropanol for 1 hour. After the membrane automatically detached from the glass plate, it was extracted in fresh isopropanol or anhydrous ethanol for two days, changing the isopropanol or anhydrous ethanol every 10 hours during these two days. Finally, it was dried in a 30°C oven for one day.

[0047] Example 3: Preparation of PMP-3D-COOH-COF-2.0 planar hybrid sheet membrane

[0048] Material formulation:

[0049] The mass ratio of poly(4-methyl-1-pentene) to diluent is 3:7, and the mass of the three-dimensional covalent organic framework 3D-COOH-COF is 2.0% of the mass of poly(4-methyl-1-pentene). Weigh the following proportions for the sheet membrane: 4.6667 g of dioctyl phthalate, 40 mg of the three-dimensional covalent organic framework 3D-COOH-COF, and 2 g of poly(4-methyl-1-pentene).

[0050] Preparation of casting solution for flat sheet membranes:

[0051] Dioctyl phthalate and the three-dimensional covalent organic framework 3D-COOH-COF were weighed and added to a 20 mL three-necked flask. The mixture was sonicated for 30 min until the 3D-COOH-COF was evenly dispersed, resulting in an orange-yellow suspension. Cell disruption was then achieved by sonicating the suspension for 30 min. 2 g of poly-4-methyl-1-pentene was added to the suspension, and the mixture was stirred at 230 °C for 6 h. The stirred casting solution was then heated to 240 °C and allowed to stand for 6 h, ready for the preparation of a flat sheet membrane.

[0052] Preparation of planar hybrid films:

[0053] A quartz glass plate was placed on a 250°C heating plate for 10 minutes. A casting solution at 240°C was poured onto one end of the glass plate, and quickly scraped to the other end using a spatula at a distance of 150 μm from the glass plate. The coated glass plate was then rapidly immersed in water to cool for 3 minutes. Next, the glass plate was extracted in anhydrous ethanol or isopropanol for 1 hour. After the membrane automatically detached from the glass plate, it was extracted in fresh isopropanol or anhydrous ethanol for two days, changing the isopropanol or anhydrous ethanol every 12 hours. Finally, it was dried in a 30°C oven for one day.

[0054] Example 4: Preparation of PMP-3D-OH-COF-5.0 planar hybrid sheet membrane

[0055] Material formulation:

[0056] The mass ratio of poly(4-methyl-1-pentene) to diluent is 4:6, and the mass of the three-dimensional covalent organic framework 3D-OH-COF is 5.0% of the mass of poly(4-methyl-1-pentene). Weigh the following proportions: for sheet membranes, weigh 3g of dioctyl phthalate, 100mg of the three-dimensional covalent organic framework 3D-OH-COF, and 2g of poly(4-methyl-1-pentene).

[0057] Preparation of casting solution for flat sheet membranes:

[0058] Dioctyl phthalate and the three-dimensional covalent organic framework 3D-OH-COF were weighed and added to a 20 mL three-necked flask. The mixture was sonicated for 30 min until the 3D-OH-COF was evenly dispersed, resulting in an orange-yellow suspension. Cell disruption was then achieved by sonicating the suspension for another 30 min. 2 g of poly-4-methyl-1-pentene was added to the suspension, and the mixture was stirred at 230 °C for 12 h. The stirred casting solution was then heated to 240 °C and allowed to stand for 12 h, ready for use in preparing a flat sheet membrane.

[0059] Preparation of planar hybrid films:

[0060] A quartz glass plate was placed on a 260°C heating plate for 10 minutes. A casting solution at 240°C was poured onto one end of the glass plate, and quickly scraped to the other end using a spatula at a distance of 200 μm from the glass plate. The coated glass plate was then rapidly immersed in water to cool for 3 minutes. Next, the glass plate was extracted in anhydrous ethanol or isopropanol for 1 hour. After the membrane automatically detached from the glass plate, it was extracted in fresh isopropanol or anhydrous ethanol for three days, with the isopropanol or anhydrous ethanol being replaced every 12 hours for two days. Finally, the membrane was dried in a 30°C oven for two days.

[0061] The present invention uses a control example 1, a poly(4-methyl-1-pentene) (PMP) flat sheet membrane, for comparison with existing poly(4-methyl-1-pentene) (PMP) flat sheet membranes.

[0062] Experimental Example 1: Test of oxygen and carbon dioxide transport performance of hybrid flat sheet membrane

[0063] The oxygen and carbon dioxide transport fluxes of the membranes prepared by PMP-3D-OH-COF-0.5, PMP-3D-OH-COF-1.0, PMP-3D-COOH-COF-2.0, PMP-3D-OH-COF-5.0, and Control Example 1 were tested using a gas flux testing device. The flat sheet membranes were encapsulated into sheets using aluminum foil tape and epoxy resin AB glue. Oxygen or carbon dioxide was introduced at 1 bar, and after stabilization, the gas flow rate was measured using a soap film flow meter.

[0064] Oxygen permeation rate and carbon dioxide permeation rate (ml / (min·cm)) of the membranes obtained in Examples 1-4 and Comparative Example 1 2 ·bar) is shown in Table 1.

[0065] Table 1. Gas permeation performance of membranes modified under different three-dimensional covalent organic framework conditions.

[0066]

[0067] like Figure 2 To test the carbon dioxide and oxygen permeation rates under pressure, the hybrid planar membrane with added three-dimensional covalent organic frameworks (3D-COF-1.0) exhibited significantly higher carbon dioxide and oxygen transport rates than the poly(4-methyl-1-pentene) planar membrane without the 3D-COF-1.0. This is mainly due to the high content of imine and benzene ring groups, high-density pores, and large specific surface area of ​​the 3D-COF-1.0. Furthermore, the carboxyl and hydroxyl groups can interact with polar carbon dioxide via dipole-quadripolar interactions, enhancing the dissolution-diffusion process of oxygen and carbon dioxide molecules through the membrane. Additionally, the good interaction and compatibility between the 3D-COF-1.0 nanosheets and poly(4-methyl-1-pentene) enhances the membrane's free volume, reducing the gas transport resistance. These multiple mechanisms work together to give the prepared hybrid planar membrane highly efficient gas transport performance. Overall, the PMP-3D-OH-COF-1.0 hybrid membrane exhibits the best oxygen and carbon dioxide gas permeability, with a carbon dioxide transport capacity of 31.96 mL / (min·cm). 2 (·bar), compared to the unhybridized poly(4-methyl-1-pentene) with a carbon dioxide transport capacity of 18.00 mL / (min·cm). 2 In terms of oxygen transport capacity (in terms of bar), it increased by 77.55%; the oxygen transport capacity was 64.37 mL / (min·cm). 2 The oxygen transport capacity of poly(4-methyl-1-pentene) is 25.74 mL / (min·cm), compared to 25.74 mL / (min·cm) of unhybridized poly(4-methyl-1-pentene). 2 For (bar), it increased by 150.08%.

[0068] Experimental Example 2: Mechanical Property Testing of Hybrid Flat Sheet Membranes

[0069] Mechanical performance testing was performed using a WDW-50N single-arm microcomputer-controlled electronic universal testing machine manufactured by Jilin Guanteng Automation Technology Co., Ltd. The film was cut into samples approximately 5 mm wide and 10 mm long. The film thickness was measured using a thickness gauge. The samples were placed vertically on the measuring instrument and clamped at 2 mm / min. -1Tensile tests were conducted at a certain speed to obtain the test force-displacement curve. The maximum force F (N) at membrane rupture and the axial deformation L-L0 (mm) were recorded. Each membrane was measured at least three times, and the average value was taken. The tensile strength was calculated using the following formula. (MPa) and elongation at break (%)

[0070]

[0071]

[0072] Where W (mm), H (mm), and L0 (mm) are the width, thickness, and initial length of the sample, respectively.

[0073] The mechanical properties of the membranes obtained in Examples 1-4 and Comparative Example 1 are shown in Table 2.

[0074] Table 2 Mechanical properties of membranes modified under different three-dimensional covalent organic framework conditions

[0075]

[0076] like Figure 3 To evaluate the mechanical properties of membranes modified under different three-dimensional covalent organic framework (3D-OCF) conditions, the hybrid sheet membrane with added 3D-OCF showed significantly better mechanical properties than the poly(4-methyl-1-pentene) sheet membrane without 3D-OCF. This is mainly due to the better interfacial compatibility between the 3D-OCF nanosheets and poly(4-methyl-1-pentene), which avoids the formation of defects and agglomeration. Overall, the PMP-3D-OH-COF-1.0 hybrid membrane exhibited the best mechanical properties, with a tensile strength of 2.12 MPa, a 12.76% increase compared to the 1.88 MPa of the unhybridized poly(4-methyl-1-pentene); and an elongation at break of 570.9%, a 14.11% increase compared to the 500.3% of the unhybridized poly(4-methyl-1-pentene). For the preparation of poly(4-methyl-1-pentene) flat sheet membranes, this invention reduces the difficulty of membrane preparation and simplifies the process by uniformly dispersing carboxylated or hydroxylated three-dimensional covalent organic frameworks in the casting solution and then forming the membrane using TIPS. Furthermore, the intertwining of the carboxylated or hydroxylated three-dimensional covalent organic frameworks and the poly(4-methyl-1-pentene) molecular chains improves the mechanical properties of the oxygenated membrane.

[0077] This invention proposes a hybrid flat sheet membrane of poly(4-methyl-1-pentene) / three-dimensional covalent organic framework, its preparation method, and its applications. The hybrid flat sheet membrane of this invention benefits from the large specific surface area, high-density functional groups, and high mechanical properties of the three-dimensional covalent organic framework. The three-dimensional covalent organic framework is blended with poly(4-methyl-1-pentene), and the hybrid membrane is prepared using a thermally induced phase separation method. The embedding of the three-dimensional covalent organic framework provides additional adsorption and transport channels for oxygen and carbon dioxide, significantly improving the gas permeability of the hybrid flat sheet membrane. Furthermore, the entanglement of the three-dimensional covalent organic framework and the poly(4-methyl-1-pentene) molecular chains enhances the mechanical properties of the hybrid flat sheet membrane, while avoiding the complex membrane structure control required in current poly(4-methyl-1-pentene) hybrid flat sheet membrane production processes aimed at improving gas transport and mechanical properties.

[0078] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many modifications under the guidance of the present invention without departing from the spirit of the present invention, and these modifications are all within the protection scope of the present invention.

Claims

1. A hybrid planar membrane of poly(4-methyl-1-pentene) / three-dimensional covalent organic framework; characterized in that, The hybrid flat sheet membrane is a flat sheet membrane based on a three-dimensional covalent organic framework and poly4-methyl-1-pentene. The thickness of the hybrid flat sheet membrane is 255-434 μm, and the thickness of the dense layer is 0.64-0.86 μm. The dense layer is a non-porous and dense skin layer, and the porous layer is a bicontinuous cellular loose structure. The three-dimensional covalent organic framework and poly4-methyl-1-pentene are uniformly dispersed. The preparation method includes the following steps: (1) Weigh the formulation materials, including dioctyl phthalate (diethyl phthalate) as a diluent, poly(4-methyl-1-pentene) and a three-dimensional covalent organic framework (3CFO). The mass percentage of the materials in the formulation is as follows: the mass ratio of poly(4-methyl-1-pentene) to dioctyl phthalate is 1:9 to 4:6, and the mass percentage of the 3CFO is 0.5-5% of that of poly(4-methyl-1-pentene). First, ultrasonically disperse and cell-break the 3CFO and dioctyl phthalate until they are evenly dispersed, and then add poly(4-methyl-1-pentene) and dioctyl phthalate. The hybrid membrane casting solution was prepared by hot stirring and allowing it to stand to degas. The three-dimensional covalent organic framework and the diluent dioctyl phthalate were ultrasonically treated for 10-30 min. After the three-dimensional covalent organic framework was evenly dispersed, the cells were disrupted by ultrasonication for 10-30 min. Poly(4-methyl-1-pentene) was added and heated to 220-230℃ and stirred for 6-12 h to fully dissolve the poly(4-methyl-1-pentene) and avoid large crystals and agglomeration. Stirring was stopped and the temperature was raised to 230-240℃ and allowed to stand for 6-12 h to degas, and the casting solution was obtained. (2) The hybrid flat film is formed by TIPS method. A scraper is selected to scrape the flat film. The quartz glass plate is placed on the heating plate. The casting solution is poured onto one end of the glass plate and quickly scraped to the other end with a scraper. The homogeneous casting solution after scraping is introduced into a water coagulation bath at room temperature to separate the solid-liquid or liquid-liquid phases and solidify. The distance between the scraper and the glass plate is 100-200μm, and the temperature of the heating plate is set to 220-260℃. (3) Add the formed flat sheet membrane to the solvent, and replace the solvent every 8-12 hours. Extract by solvent exchange for 2-3 days. (4) Place the flat sheet membrane obtained after extraction in step (3) in a room temperature oven to dry for 1-2 days.

2. The method for preparing the hybrid planar membrane of poly(4-methyl-1-pentene) / three-dimensional covalent organic framework as described in claim 1; characterized in that, Includes the following steps: (1) Weigh the formulation materials, including dioctyl phthalate diluent, poly-4-methyl-1-pentene and three-dimensional covalent organic framework; the mass percentage of the material formulation is: the mass ratio of poly-4-methyl-1-pentene to dioctyl phthalate diluent is 1:9~4:6, and the mass percentage of three-dimensional covalent organic framework is 0.5-5% of poly-4-methyl-1-pentene; first, ultrasonically disperse and cell break down the three-dimensional covalent organic framework and dioctyl phthalate diluent until they are uniformly dispersed, then add poly-4-methyl-1-pentene, heat and stir, and let stand to degas to prepare the hybrid membrane casting solution; (2) The hybrid flat sheet membrane is formed by TIPS method. A scraper is selected to scrape the flat sheet membrane. The homogeneous casting liquid after scraping is introduced into a water coagulation bath at room temperature along with the glass plate to cause solid-liquid or liquid-liquid phase separation and solidification. (3) Add the formed flat sheet membrane to the solvent, and replace the solvent every 8-12 hours. Extract by solvent exchange for 2-3 days. (4) Place the flat sheet membrane obtained after extraction in step (3) in a room temperature oven to dry for 1-2 days.

3. The preparation method as described in claim 2; characterized in that, In step (3), the solvent is one or more of anhydrous ethanol and isopropanol; the extraction process lasts for 2-3 days, and the solvent is changed every 8-12 hours.

4. The preparation method as described in claim 2; characterized in that, In step (4), the oven temperature is 20-30℃.

5. The application of the poly(4-methyl-1-pentene) / three-dimensional covalent organic framework hybrid flat sheet membrane as described in claim 1 in the field of extracorporeal membrane oxygenation.

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