A kind of sheet polyimide nanoflower-polyamide composite film and its preparation method and application

Abstract

The application discloses a kind of polyimide nanoflower-polyamide composite membrane with sheet layer structure and its preparation method and application, specifically includes: selecting aromatic diamine and aromatic dianhydride by hydrothermal method to prepare flower-like polyimide particles with close sheet structure;Degree of imidization of nanoflower is controlled by soaking lye or high-temperature treatment method;The obtained nanoflower is uniformly dispersed in acyl chloride oil phase solution, and it is introduced into polyamide separation layer by interfacial polymerization process, i.e.polyimide nanoflower-polyamide composite membrane material is obtained.The preparation method can ensure that the loading of organic nanoparticles and interfacial polymerization reaction proceed synchronously, effectively avoid particle agglomeration and interface defect.At the same time, the prepared composite membrane material has excellent moisture permeability and gas barrier performance.The application can be applied to air energy recovery, air conditioning heating energy recovery, indoor air purification, air dehumidification and heat and moisture recovery, chemical environmental protection field.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of moisture permeable and gas resistant and heat recovery, and particularly relates to a polyimide-polyamide composite film with high gas resistance, high moisture permeability and high energy recovery, and a preparation method and application thereof. BACKGROUND

[0002] With the development of society, the development of low-carbon economy is advocated, and energy saving and emission reduction is becoming more and more important. Most of the energy consumption in the world is generated by industry and construction, of which the building energy consumption accounts for 1 / 3 of the total social energy consumption, and the energy consumption of heating and air conditioning in the building use process accounts for about 65% of the total energy consumption, and the fresh air load accounts for more than 30% of the air conditioning system (Build. Environ, 2020, 168: 1-16). As an important component of the air conditioning system, the exhaust air contains a large amount of energy, therefore, reducing the energy consumption of the fresh air system is of great significance to energy saving (Renew. Sust. Energ. Rev, 2022, 167: 112669).

[0003] At present, the full heat exchange components for energy recovery of fresh air system on the market usually adopt rotary and polymer membrane types. Full heat exchange is composed of sensible heat exchange and latent heat exchange. The sensible heat exchange between indoor and outdoor is driven by the temperature difference between the two. The latent heat exchange is the transfer of water molecules from the high humidity side to the low humidity side of the polymer membrane through dissolution and diffusion. Commercial paper membranes applied in heat recovery systems on the market have good temperature and humidity exchange efficiency and enthalpy exchange efficiency, but almost no gas resistance, which cannot block CO2 and other exhaust gases in the exhaust air, and is easy to cause cross contamination (Building Science, 2017, 33(8): 17-22). Therefore, under the premise of ensuring that the heat exchanger has high energy recovery rate, how to further improve the moisture permeability and gas resistance of the membrane component has become the core of the research.

[0004] Polyamide, polyvinyl alcohol, chitosan and cellulose and other organic high molecular materials with hydrophilic groups have been used to construct full heat exchange membranes with high moisture permeability, but they still face the bottleneck problem of low gas resistance (J. Membr. Sci, 2011, 367(1-2): 182-189; J. Membr. Sci, 2022, 662: 120956).

[0005] Therefore, the full heat exchange membrane at the present stage generally exists the "trade-off" effect between gas resistance and moisture permeability, gas resistance and energy recovery rate, that is, it cannot simultaneously satisfy high gas resistance, high moisture permeability and high heat recovery efficiency. Therefore, the polymer membrane material has a positive development prospect in full heat exchange, fresh air system with heat recovery, energy saving and emission reduction, and it is crucial to develop a diaphragm material with high gas resistance, excellent moisture permeability and ultra-high energy recovery rate. SUMMARY

[0006] In order to overcome the deficiencies of the prior art, the purpose of the present application is to provide a sheet-layer polyimide nanoflower-polyamide composite film with high gas barrier properties, good moisture permeability and energy recovery efficiency, and a preparation method and application thereof, which is mainly used to solve the problem of poor gas barrier property of commercial membranes in the field of total heat exchange and fresh air system.

[0007] The present application aims to prepare sheet-layer polyimide nanoflowers with different structures of aromatic diamines and aromatic dianhydrides by a hydrothermal method. By utilizing its gas barrier separation properties and excellent compatibility with the polymer matrix, the sheet-layer polyimide nanoflowers participate in the interfacial polymerization of the polyamide separation layer on the porous support material. The sheet-layer polyimide nanoflower-polyamide composite film prepared by the present application has ultra-high gas barrier (CO2) performance, high moisture permeability and good heat recovery efficiency. The present application has good application prospects in the fields of air energy recovery, air conditioning heating energy recovery, indoor air purification, air dehumidification and heat and moisture recovery, etc.

[0008] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0009] A sheet-layer polyimide nanoflower-polyamide composite film, which is composed of a polymer porous support layer, a polyamide active separation layer and sheet-layer polyimide nanoflowers. The nanoflowers participate in the crosslinking polymerization of the polyamide and are embedded in the surface of the separation layer.

[0010] The polymer porous support layer is one of polyester, polyolefin and nylon; and the surface is coated with a layer of polysulfone.

[0011] The polyamide separation layer is prepared by immersing water-phase monomers and oil-phase monomers on the surface of the support layer in sequence, and then through interfacial polymerization and heat curing.

[0012] The sheet-layer polyimide nanoflowers have a particle size of 1.5-3.5 um and a specific surface area of 10-300 m 2 / g.

[0013] The sheet-layer polyimide nanoflowers are prepared by a hydrothermal method from aromatic diamines and aromatic dianhydrides in an aprotic polar solvent, and can be further treated with alkali or heat.

[0014] This invention utilizes aromatic diamines and aromatic dianhydrides to prepare flower-like polyimide particles with a tightly layered structure via a hydrothermal method. The imidization degree of the nanoflowers is controlled by immersion in an alkaline solution or high-temperature treatment. The resulting nanoflowers are uniformly dispersed in an acyl chloride oil phase solution and introduced into a polyamide separation layer through interfacial polymerization, thus obtaining the polyimide nanoflower-polyamide composite membrane material. This preparation method ensures that the loading of organic nanoparticles and the interfacial polymerization reaction occur simultaneously, effectively avoiding particle agglomeration and interfacial defects. Furthermore, the prepared composite membrane material possesses excellent moisture permeability and gas barrier properties. This invention can be applied to air energy recovery, air conditioning and HVAC energy recovery, indoor air purification, air dehumidification and heat and moisture recovery, and the chemical and environmental protection fields.

[0015] A layered polyimide nanoflower-polyamide composite membrane, wherein the composite membrane is formed by the cross-linking polymerization of polyamide on a porous polymer support layer consisting of layered nanoflowers.

[0016] (1) Place the aromatic diamine monomer in a three-necked flask, add an aprotic polar solvent under a nitrogen atmosphere, stir at room temperature until completely dissolved, add an equimolar amount of aromatic dianhydride monomer, rinse the beaker and inner wall with an aprotic polar solvent, stir for 8 to 24 hours to generate a 70 to 200 mg / mL polyamic acid solution.

[0017] (2) The polyamic acid solution prepared in step (1) is diluted to a concentration of 10-70 mg / mL and transferred to a polytetrafluoroethylene hydrothermal reactor for solvothermal polymerization. The solution is placed in an oven at 140-180℃ for 2-12 hours for high-temperature condensation and high-pressure crystallization to obtain polyimide nanoflower particles. The product is repeatedly washed with aprotic polar solvent and ethanol, dried in an oven, and collected for later use.

[0018] (3) The particles obtained in step (2) are subjected to ring-opening modification by soaking in 0.1-0.5 mol / L KOH or NaOH alkaline solution for 6-48 h; and the particles are subjected to imidization by vacuum drying oven at 250-300℃ for 3-15 h.

[0019] (4) Select a polytetrafluoroethylene plate frame to fix the porous polymer support layer, and prepare a 20 g / L aqueous monomer solution and a 1 g / L oil monomer solution. Immerse the support layer surface with 20-50 mL of aqueous monomer solution for 3-10 min, pour off the excess solution, and blow away water droplets on the membrane surface;

[0020] (5) Weigh 2-10 mg of the polyimide nanoflowers obtained in step (2) or step (3) and disperse them evenly in the oil phase monomer solution, and sonicate for 10 min.

[0021] (6) Contact the solution obtained in step (5) with the surface of the film formed in step (4) for 1 to 10 minutes to allow the interfacial polymerization and nanoflower loading to proceed simultaneously. Pour off the excess solution, blow away the water droplets on the surface, and transfer it to a forced-air drying oven at 40 to 70°C for 10 to 60 minutes to heat and cure it, thereby obtaining the sheet-like polyimide nanoflower-polyamide composite film.

[0022] In step (1), the aromatic diamine is selected from one or more of m-phenylenediamine, p-phenylenediamine, 2,4,6-trimethylm-phenylenediamine, 3,5-diaminobenzoic acid, diaminodiphenyl ether, and diaminobenzidine;

[0023] In step (1), the aromatic dianhydride is selected from one or more of dimethyltetracarboxylic dianhydride, pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, hexafluorodianhydride, diphenyl ether tetracarboxylic dianhydride, and biphenyl ketone tetracarboxylic dianhydride;

[0024] In step (1), the aprotic polar solvent is one or more of N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.

[0025] The aromatic diamine and the aromatic dianhydride monomer are used in the same molar amounts.

[0026] In step (1), the polyimide nanoflowers have a particle size of 1.5–3.5 μm and a specific surface area of ​​10–300 m². 2 / g.

[0027] In step (4), the polymer porous support layer is one of polyester, polyolefin, and nylon; the surface is coated with a polysulfone layer.

[0028] In step (4), the aqueous monomer is one or more of m-phenylenediamine, p-phenylenediamine, piperazine, o-phenylenediamine, diethylenetriamine, and triethylenetetramine; the solvent is water. The amount of aqueous monomer used for impregnation is 20-50 mL, and the impregnation time is 3-10 min.

[0029] In step (5), the oil phase monomer is one or more of pyromellitic methyl methacrylate, isophthaloyl chloride, terephthaloyl chloride, and polysulfonyl chloride; the solvent is one or more of n-hexane, n-heptane, n-octane, n-dodecane, isododecane, and isohexadecane.

[0030] The mass concentration ratio of the aqueous monomer solution to the oil monomer solution in steps (4) and (5) is 20:1.

[0031] This invention also provides the application of the above-mentioned layered polyimide nanoflower-polyamide composite membrane in moisture permeability, gas barrier, and heat recovery, specifically including:

[0032] (1) The water vapor transmission rate was evaluated using a water vapor transmission tester. The water vapor transmission rate was measured by weighing under test conditions of system temperature 38.0±1℃ and relative humidity 90.0%RH.

[0033] (2) The membrane gas barrier performance was evaluated using a carbon dioxide permeation test device (self-built). The carbon dioxide permeation rate was calculated by recording the time required to collect 5 mL of CO2 gas after the pressure stabilized for 30 min at a constant test temperature of 25±1℃ and a test pressure of 0.3±0.005MPa.

[0034] (3) A total heat exchange tester was set up to evaluate the membrane heat recovery performance. The heat / enthalpy exchange efficiency was calculated from the temperature and humidity changes of the airflow on both sides of the membrane under equilibrium conditions.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] (1) The layered polyimide nanoflowers in this invention have good thermochemical stability, excellent gas barrier separation characteristics, easy structure control, and simple synthesis.

[0037] (2) The layered polyimide nanoflowers in this invention, as organic fillers, can be uniformly and stably dispersed in the aqueous phase and organic phase, and have good interaction with the polyamide separation layer.

[0038] (3) The preparation conditions of the sheet-like polyimide nanoflower-polyamide composite film of the present invention are mild, which can realize the simultaneous loading of nanoparticles and interfacial polymerization, and can effectively solve the problems of uneven particle dispersion, easy agglomeration and interfacial defects.

[0039] (4) The prepared sheet-like polyimide nanoflower-polyamide composite membrane, when applied to total heat exchange energy recovery, exhibits excellent moisture permeability and gas barrier properties (water vapor permeability 1950 g / (m²)). 2 (24h) and CO2 permeability 3.64 GPU). Meanwhile, this membrane possesses heat exchange efficiency (97.47%) and enthalpy exchange efficiency (71.41%) comparable to commercial paper membranes, providing a feasible solution for the preparation of novel high-efficiency total heat exchange membranes. Attached Figure Description

[0040] Figure 1 This is an electron micrograph of layered polyimide nanoflowers. The particles are regularly sized and shaped, exhibiting a layered structure.

[0041] Figure 2 This is an electron micrograph of the surface of a layered polyimide nanoflower-polyamide composite film.

[0042] Figure 3Electron micrographs of the membrane surface with four different amounts of nanoflowers added: (a) no nanoflowers added; (b) 2 mg nanoflowers added; (c) 5 mg nanoflowers added; (d) 8 mg nanoflowers added.

[0043] Figure 4 The image shows the FTIR spectrum of polyimide nanoflowers. Nanoflowers with 92% imidization were prepared under the above conditions. Nanoflowers with 82% imidization were obtained by etching with NaOH for 12 hours. Completely imidized nanoflowers were obtained by high-temperature treatment at 300℃. The degree of imidization was calculated from the peak area of ​​the infrared spectrum.

[0044] Figure 5 The XRD pattern of the layered polyimide nanoflowers shows high crystallinity, confirming that they are loaded onto the film surface. Detailed Implementation

[0045] The present invention is further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0046] Example 1

[0047] (1) 5.2448 g of p-phenylenediamine was placed in a three-necked flask, and 180 mL of N,N-dimethylformamide was added under a nitrogen atmosphere. The mixture was stirred at room temperature until completely dissolved. 15.6277 g of 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added in portions. The beaker and inner wall were rinsed with 180 mL of N,N-dimethylformamide, and the mixture was stirred to generate a 70 mg / mL polyamic acid solution. The solution was then diluted to 46 mg / mL and transferred to a polytetrafluoroethylene hydrothermal reactor for solvothermal polymerization. The mixture was placed in an oven at 180 °C for 6 h for high-temperature condensation and high-pressure crystallization to obtain polyimide nanoflower particles. Finally, the product was repeatedly washed with N,N-dimethylformamide and ethanol, dried in an oven, and collected for later use to obtain polyimide nanoflowers with an imidization degree of 92%.

[0048] (2) A polytetrafluoroethylene (PTFE) plate and frame was used to fix the polysulfone ultrafiltration membrane. A 20 g / L m-phenylenediamine-water solution and a 1 g / L trimesoyl chloride-n-hexane solution were prepared. 2 mg of polyimide nanoflowers were weighed and added to 40 mL of trimesoyl chloride-n-hexane solution, and dispersed by sonication for 10 min. The polysulfone substrate was then immersed in 40 mL of the m-phenylenediamine-water solution for 3 min, excess solution was poured off, and water droplets on the membrane surface were blown away. The membrane was then immersed in the trimesoyl chloride-n-hexane solution containing polyimide for 1 min, excess solution was poured off, and water droplets on the surface were blown away. Finally, the membrane was transferred to a 70°C forced-air drying oven and heated for 10 min for further thermosetting.

[0049] The polyimide-polyamide composite membrane prepared in Example 1 had a carbon dioxide permeability of 3.64 GPU and a water vapor permeability of 1949.51 g / (m²). 2•24h).

[0050] like Figure 1 The image shows an electron micrograph of layered polyimide nanoflowers. The particles are regularly sized and shaped, exhibiting a layered structure.

[0051] like Figure 2 The image shows an electron microscope image of the surface of the layered polyimide nanoflower-polyamide composite film.

[0052] like Figure 3 As shown, electron micrographs of the membrane surface with four different amounts of nanoflowers are presented: (a) no nanoflowers added; (b) 2 mg nanoflowers added; (c) 5 mg nanoflowers added; and (d) 8 mg nanoflowers added.

[0053] like Figure 4 The image shows the FTIR spectrum of polyimide nanoflowers. Nanoflowers with 92% imidization were prepared under the above conditions. Nanoflowers with 82% imidization were obtained by etching with NaOH for 12 hours. Completely imidized nanoflowers were obtained by high-temperature treatment at 300℃. The degree of imidization was calculated from the peak area of ​​the infrared spectrum.

[0054] like Figure 5 The XRD pattern of the layered polyimide nanoflowers shown in the figure has high crystallinity, confirming that they are loaded on the film surface.

[0055] Example 2

[0056] (1) 5.2448 g of p-phenylenediamine was placed in a three-necked flask, and 180 mL of N,N-dimethylformamide was added under a nitrogen atmosphere. The mixture was stirred at room temperature until completely dissolved. 15.6277 g of 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added in portions. The beaker and inner wall were rinsed with 180 mL of N,N-dimethylformamide, and the mixture was stirred to generate a 70 mg / mL polyamic acid solution. The solution was then diluted to 46 mg / mL and transferred to a polytetrafluoroethylene hydrothermal reactor for solvothermal polymerization. The mixture was placed in an oven at 180 °C for 6 h for high-temperature condensation and high-pressure crystallization to obtain polyimide nanoflower particles. Finally, the product was repeatedly washed with N,N-dimethylformamide and ethanol, dried in an oven, and collected for later use to obtain polyimide nanoflowers with an imidization degree of 92%.

[0057] (2) A polytetrafluoroethylene (PTFE) plate and frame was used to fix the polysulfone ultrafiltration membrane. A 20 g / L m-phenylenediamine-water solution and a 1 g / L trimesoyl chloride-n-hexane solution were prepared. 5 mg of polyimide nanoflowers were weighed and added to 40 mL of trimesoyl chloride-n-hexane solution, and dispersed by sonication for 10 min. The polysulfone substrate was then immersed in 40 mL of the m-phenylenediamine-water solution for 3 min, excess solution was poured off, and water droplets on the membrane surface were blown away. The membrane was then immersed in the trimesoyl chloride-n-hexane solution containing polyimide for 1 min, excess solution was poured off, and water droplets on the surface were blown away. Finally, the membrane was transferred to a 70°C forced-air drying oven and heated for 10 min for further thermosetting.

[0058] The polyimide-polyamide composite membrane prepared in Example 2 had a carbon dioxide permeability of 5.54 GPU and a water vapor permeability of 1930.24 g / (m²). 2 •24h).

[0059] Example 3

[0060] (1) 5.2448 g of p-phenylenediamine was placed in a three-necked flask, and 180 mL of N,N-dimethylformamide was added under a nitrogen atmosphere. The mixture was stirred at room temperature until completely dissolved. 15.6277 g of 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added in portions. The beaker and inner wall were rinsed with 180 mL of N,N-dimethylformamide, and the mixture was stirred to generate a 70 mg / mL polyamic acid solution. The solution was then diluted to 46 mg / mL and transferred to a polytetrafluoroethylene hydrothermal reactor for solvothermal polymerization. The mixture was placed in an oven at 180 °C for 6 h for high-temperature condensation and high-pressure crystallization to obtain polyimide nanoflower particles. Finally, the product was repeatedly washed with N,N-dimethylformamide and ethanol, dried in an oven, and collected for later use to obtain polyimide nanoflowers with an imidization degree of 92%.

[0061] (2) A polytetrafluoroethylene (PTFE) plate and frame was used to fix the polysulfone ultrafiltration membrane. A 20 g / L m-phenylenediamine-water solution and a 1 g / L trimesoyl chloride-n-hexane solution were prepared. 8 mg of polyimide nanoflowers were weighed and added to 40 mL of trimesoyl chloride-n-hexane solution, and dispersed by sonication for 10 min. The polysulfone substrate was then immersed in 40 mL of the m-phenylenediamine-water solution for 3 min, excess solution was discarded, and water droplets on the membrane surface were blown away. The membrane was then immersed in the trimesoyl chloride-n-hexane solution containing polyimide for 1 min, excess solution was discarded, and water droplets on the surface were blown away. Finally, the membrane was transferred to a 70°C forced-air drying oven and heated for 10 min for further thermosetting.

[0062] The polyimide-polyamide composite membrane prepared in Example 3 had a carbon dioxide permeability of 10.02 GPU and a water vapor permeability of 1944.21 g / (m³). 2 •24h).

[0063] Example 4

[0064] (1) 5.2448 g of p-phenylenediamine was placed in a three-necked flask, and 180 mL of N,N-dimethylformamide was added under a nitrogen atmosphere. The mixture was stirred at room temperature until completely dissolved. 15.6277 g of 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added in portions. The beaker and inner wall were rinsed with 180 mL of N,N-dimethylformamide, and the mixture was stirred to generate a 70 mg / mL polyamic acid solution. The solution was then diluted to 46 mg / mL and transferred to a polytetrafluoroethylene hydrothermal reactor for solvothermal polymerization. The mixture was placed in an oven at 180 °C for 6 h for high-temperature condensation and high-pressure crystallization to obtain polyimide nanoflower particles. The product was repeatedly washed with N,N-dimethylformamide and ethanol, and then soaked in 0.1 mol / L NaOH alkaline solution for 24 h for ring-opening modification. Finally, the product was dried in an oven and collected for later use to obtain polyimide nanoflowers with an imidization degree of 82%.

[0065] (2) A polytetrafluoroethylene (PTFE) plate and frame was used to fix the polysulfone ultrafiltration membrane. A 20 g / L m-phenylenediamine-water solution and a 1 g / L trimesoyl chloride-n-hexane solution were prepared. 2 mg of polyimide nanoflowers were weighed and added to 40 mL of trimesoyl chloride-n-hexane solution, and dispersed by sonication for 10 min. The polysulfone substrate was then immersed in 40 mL of the m-phenylenediamine-water solution for 3 min, excess solution was poured off, and water droplets on the membrane surface were blown away. The membrane was then immersed in the trimesoyl chloride-n-hexane solution containing polyimide for 1 min, excess solution was poured off, and water droplets on the surface were blown away. Finally, the membrane was transferred to a 70°C forced-air drying oven and heated for 10 min for further thermosetting.

[0066] The polyimide-polyamide composite membrane prepared in Example 4 had a carbon dioxide permeability of 0.51 GPU and a water vapor permeability of 1935.82 g / (m²). 2 (24h), heat exchange efficiency 97.47%, enthalpy exchange efficiency 71.41%.

[0067] Example 5

[0068] (1) 5.2448 g of p-phenylenediamine was placed in a three-necked flask, and 180 mL of N,N-dimethylformamide was added under a nitrogen atmosphere. The mixture was stirred at room temperature until completely dissolved. 15.6277 g of 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added in portions. The beaker and inner wall were rinsed with 180 mL of N,N-dimethylformamide, and the mixture was stirred to generate a 70 mg / mL polyamic acid solution. The solution was then diluted to 46 mg / mL and transferred to a polytetrafluoroethylene hydrothermal reactor for solvothermal polymerization. The mixture was placed in an oven at 180 °C for 6 h for high-temperature condensation and high-pressure crystallization to obtain polyimide nanoflower particles. The product was repeatedly washed with N,N-dimethylformamide and ethanol, and then soaked in 0.1 mol / L NaOH alkaline solution for 24 h for ring-opening modification. Finally, the product was dried in an oven and collected for later use to obtain polyimide nanoflowers with an imidization degree of 82%.

[0069] (2) A polytetrafluoroethylene (PTFE) plate and frame was used to fix the polysulfone ultrafiltration membrane. A 20 g / L m-phenylenediamine-water solution and a 1 g / L trimesoyl chloride-n-hexane solution were prepared. 5 mg of polyimide nanoflowers were weighed and added to 40 mL of trimesoyl chloride-n-hexane solution, and dispersed by sonication for 10 min. The polysulfone substrate was then immersed in 40 mL of the m-phenylenediamine-water solution for 3 min, excess solution was poured off, and water droplets on the membrane surface were blown away. The membrane was then immersed in the trimesoyl chloride-n-hexane solution containing polyimide for 1 min, excess solution was poured off, and water droplets on the surface were blown away. Finally, the membrane was transferred to a 70°C forced-air drying oven and heated for 10 min for further thermosetting.

[0070] The polyimide-polyamide composite membrane prepared in Example 5 had a carbon dioxide permeability of 0.34 GPU and a water vapor permeability of 2183.15 g / (m²). 2 •24h).

[0071] Example 6

[0072] (1) 5.2448 g of p-phenylenediamine was placed in a three-necked flask, and 180 mL of N,N-dimethylformamide was added under a nitrogen atmosphere. The mixture was stirred at room temperature until completely dissolved. 15.6277 g of 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added in portions. The beaker and inner wall were rinsed with 180 mL of N,N-dimethylformamide, and the mixture was stirred to generate a 70 mg / mL polyamic acid solution. The solution was then diluted to 46 mg / mL and transferred to a polytetrafluoroethylene hydrothermal reactor for solvothermal polymerization. The mixture was placed in an oven at 180 °C for 6 h for high-temperature condensation and high-pressure crystallization to obtain polyimide nanoflower particles. The product was repeatedly washed with N,N-dimethylformamide and ethanol, and then soaked in 0.1 mol / L NaOH alkaline solution for 24 h for ring-opening modification. Finally, the product was dried in an oven and collected for later use to obtain polyimide nanoflowers with an imidization degree of 82%.

[0073] (2) A polytetrafluoroethylene (PTFE) plate and frame was used to fix the polysulfone ultrafiltration membrane. A 20 g / L m-phenylenediamine-water solution and a 1 g / L trimesoyl chloride-n-hexane solution were prepared. 8 mg of polyimide nanoflowers were weighed and added to 40 mL of trimesoyl chloride-n-hexane solution, and dispersed by sonication for 10 min. The polysulfone substrate was then immersed in 40 mL of the m-phenylenediamine-water solution for 3 min, excess solution was discarded, and water droplets on the membrane surface were blown away. The membrane was then immersed in the trimesoyl chloride-n-hexane solution containing polyimide for 1 min, excess solution was discarded, and water droplets on the surface were blown away. Finally, the membrane was transferred to a 70°C forced-air drying oven and heated for 10 min for further thermosetting.

[0074] The polyimide-polyamide composite membrane prepared in Example 6 had a carbon dioxide permeability of 3.59 GPU and a water vapor permeability of 2195.31 g / (m²). 2 •24h).

[0075] Example 7

[0076] (1) 5.2448 g of p-phenylenediamine was placed in a three-necked flask, and 180 mL of N,N-dimethylformamide was added under a nitrogen atmosphere. The mixture was stirred at room temperature until completely dissolved. 15.6277 g of 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added in portions. The beaker and inner wall were rinsed with 180 mL of N,N-dimethylformamide, and the mixture was stirred to generate a 70 mg / mL polyamic acid solution. The solution was then diluted to 46 mg / mL and transferred to a polytetrafluoroethylene hydrothermal reactor for solvothermal polymerization. The mixture was placed in an oven at 180 °C for 6 h for high-temperature condensation and high-pressure crystallization to obtain polyimide nanoflower particles. The product was repeatedly washed with N,N-dimethylformamide and ethanol, dried, and then treated in a vacuum drying oven at 300 °C for 3 h to complete the imidization of the particles.

[0077] (2) A polytetrafluoroethylene (PTFE) plate and frame was used to fix the polysulfone ultrafiltration membrane. A 20 g / L m-phenylenediamine-water solution and a 1 g / L trimesoyl chloride-n-hexane solution were prepared. 2 mg of polyimide nanoflowers were weighed and added to 40 mL of trimesoyl chloride-n-hexane solution, and dispersed by sonication for 10 min. The polysulfone substrate was then immersed in 40 mL of the m-phenylenediamine-water solution for 3 min, excess solution was poured off, and water droplets on the membrane surface were blown away. The membrane was then immersed in the trimesoyl chloride-n-hexane solution containing polyimide for 1 min, excess solution was poured off, and water droplets on the surface were blown away. Finally, the membrane was transferred to a 70°C forced-air drying oven and heated for 10 min for further thermosetting.

[0078] The polyimide-polyamide composite membrane prepared in Example 7 had a carbon dioxide permeability of 9.50 GPU and a water vapor permeability of 2068.26 g / (m²). 2 •24h).

[0079] Example 8

[0080] (1) 5.2448 g of p-phenylenediamine was placed in a three-necked flask, and 180 mL of N,N-dimethylformamide was added under a nitrogen atmosphere. The mixture was stirred at room temperature until completely dissolved. 15.6277 g of 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added in portions. The beaker and inner wall were rinsed with 180 mL of N,N-dimethylformamide, and the mixture was stirred to generate a 70 mg / mL polyamic acid solution. The solution was then diluted to 46 mg / mL and transferred to a polytetrafluoroethylene hydrothermal reactor for solvothermal polymerization. The mixture was placed in an oven at 180 °C for 6 h for high-temperature condensation and high-pressure crystallization to obtain polyimide nanoflower particles. The product was repeatedly washed with N,N-dimethylformamide and ethanol, dried, and then treated in a vacuum drying oven at 300 °C for 3 h to complete the imidization of the particles.

[0081] (2) A polytetrafluoroethylene (PTFE) plate-frame was used to fix the polysulfone ultrafiltration membrane. A 20 g / L m-phenylenediamine-water solution and a 1 g / L trimesoyl chloride-n-hexane solution were prepared. 5 mg of polyimide (100% imidization) nanoflowers were weighed and added to 40 mL of trimesoyl chloride-n-hexane solution, and dispersed by sonication for 10 min. The polysulfone substrate was then immersed in 40 mL of the m-phenylenediamine-water solution for 3 min, excess solution was discarded, and water droplets on the membrane surface were blown away. The membrane was then immersed in the trimesoyl chloride-n-hexane solution containing polyimide for 1 min, excess solution was discarded, and water droplets on the surface were blown away. Finally, the membrane was transferred to a 70°C forced-air drying oven and heated for 10 min for further thermosetting.

[0082] The polyimide-polyamide composite membrane prepared in Example 8 had a carbon dioxide permeability of 12.49 GPU and a water vapor permeability of 2230.37 g / (m²). 2 •24h).

[0083] Example 9

[0084] (1) 5.2448 g of p-phenylenediamine was placed in a three-necked flask, and 180 mL of N,N-dimethylformamide was added under a nitrogen atmosphere. The mixture was stirred at room temperature until completely dissolved. 15.6277 g of 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added in portions. The beaker and inner wall were rinsed with 180 mL of N,N-dimethylformamide, and the mixture was stirred to generate a 70 mg / mL polyamic acid solution. The solution was then diluted to 46 mg / mL and transferred to a polytetrafluoroethylene hydrothermal reactor for solvothermal polymerization. The mixture was placed in an oven at 180 °C for 6 h for high-temperature condensation and high-pressure crystallization to obtain polyimide nanoflower particles. The product was repeatedly washed with N,N-dimethylformamide and ethanol, dried, and then treated in a vacuum drying oven at 300 °C for 3 h to complete the imidization of the particles.

[0085] (2) A polytetrafluoroethylene (PTFE) plate and frame was used to fix the polysulfone ultrafiltration membrane. A 20 g / L m-phenylenediamine-water solution and a 1 g / L trimesoyl chloride-n-hexane solution were prepared. 8 mg of polyimide nanoflowers were weighed and added to 40 mL of trimesoyl chloride-n-hexane solution, and dispersed by sonication for 10 min. The polysulfone substrate was then immersed in 40 mL of the m-phenylenediamine-water solution for 3 min, excess solution was discarded, and water droplets on the membrane surface were blown away. The membrane was then immersed in the trimesoyl chloride-n-hexane solution containing polyimide for 1 min, excess solution was discarded, and water droplets on the surface were blown away. Finally, the membrane was transferred to a 70°C forced-air drying oven and heated for 10 min for further thermosetting.

[0086] The polyimide-polyamide composite membrane prepared in Example 9 had a carbon dioxide permeability of 12.69 GPU and a water vapor permeability of 2229.32 g / (m²). 2 •24h).

[0087] Comparative Example 1

[0088] A polytetrafluoroethylene (PTFE) plate-frame was used to fix a polysulfone ultrafiltration membrane. A 20 g / L m-phenylenediamine-water solution and a 1 g / L trimesoyl chloride-n-hexane solution were prepared. 40 mL of the m-phenylenediamine-water solution was used to wet the polysulfone membrane substrate for 3 minutes, excess solution was poured off, and water droplets on the membrane surface were blown away. Then, 40 mL of the trimesoyl chloride-n-hexane solution was used to wet the membrane for 1 minute, excess solution was poured off, and water droplets on the surface were blown away. Finally, the membrane was transferred to a 70°C forced-air drying oven and heated for 10 minutes for further thermosetting.

[0089] The polyimide-polyamide composite membrane prepared in Comparative Example 1 had a carbon dioxide permeability of 21.04 GPU and a water vapor permeability of 1763.45 g / (m²). 2 (24h), heat exchange efficiency 95.59%, enthalpy exchange efficiency 71.43%.

[0090] Comparative Example 2

[0091] (1) 5.2448 g of p-phenylenediamine was placed in a three-necked flask, and 180 mL of N,N-dimethylformamide was added under a nitrogen atmosphere. The mixture was stirred at room temperature until completely dissolved. 15.6277 g of 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added in portions. The beaker and inner wall were rinsed with 180 mL of N,N-dimethylformamide, and the mixture was stirred to generate a 70 mg / mL polyamic acid solution. The solution was then diluted to 46 mg / mL and transferred to a polytetrafluoroethylene hydrothermal reactor for solvothermal polymerization. The mixture was placed in an oven at 180 °C for 6 h for high-temperature condensation and high-pressure crystallization to obtain polyimide nanoflower particles. Finally, the product was repeatedly washed with N,N-dimethylformamide and ethanol, dried in an oven, and collected for later use to obtain polyimide nanoflowers with an imidization degree of 92%.

[0092] (2) A membrane fabrication process was adopted in which particles were pre-loaded onto a polysulfone support layer. A polytetrafluoroethylene (PTFE) plate and frame were used to fix the polysulfone ultrafiltration membrane. A 20 g / L m-phenylenediamine-water solution and a 1 g / L trimesoyl chloride-n-hexane solution were prepared. 2 mg of polyimide nanoflowers were weighed and added to 20 mL of n-hexane. The mixture was ultrasonically dispersed for 10 min, and the solution was used to wet the polysulfone substrate for 5 min, then poured off and the water droplets on the membrane surface were blown away. 40 mL of m-phenylenediamine-water solution was first used to wet the membrane for 3 min, then the excess solution was poured off and the water droplets on the membrane surface were blown away. Then, 40 mL of trimesoyl chloride-n-hexane solution was used to wet the membrane for 1 min, then the excess solution was poured off and the water droplets on the surface were blown away. Finally, the membrane was transferred to a 70 °C forced-air drying oven and heated for 10 min for further thermosetting.

[0093] The polyimide-polyamide composite membrane prepared in Comparative Example 2 had a carbon dioxide permeability of 4.72 GPU and a water vapor permeability of 1836.87 g / (m²). 2 •24h).

[0094] Comparative Example 3

[0095] (1) 5.2448 g of p-phenylenediamine was placed in a three-necked flask, and 180 mL of N,N-dimethylformamide was added under a nitrogen atmosphere. The mixture was stirred at room temperature until completely dissolved. 15.6277 g of 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added in portions. The beaker and inner wall were rinsed with 180 mL of N,N-dimethylformamide, and the mixture was stirred to generate a 70 mg / mL polyamic acid solution. The solution was then diluted to 46 mg / mL and transferred to a polytetrafluoroethylene hydrothermal reactor for solvothermal polymerization. The mixture was placed in an oven at 180 °C for 6 h for high-temperature condensation and high-pressure crystallization to obtain polyimide nanoflower particles. Finally, the product was repeatedly washed with N,N-dimethylformamide and ethanol, dried in an oven, and collected for later use to obtain polyimide nanoflowers with an imidization degree of 92%.

[0096] (2) A membrane fabrication process was adopted in which particles were added along with the aqueous monomer to participate in interfacial polymerization. A polytetrafluoroethylene (PTFE) plate and frame were used to fix a polysulfone ultrafiltration membrane, and a 20 g / L m-phenylenediamine-water solution and a 1 g / L trimesoyl chloride-n-hexane solution were prepared. 2 mg of polyimide nanoflowers were weighed and added to 40 mL of m-phenylenediamine-water solution, and dispersed by sonication for 10 min. The solution was then used to wet the polysulfone substrate membrane for 3 min, and the excess solution was poured off and the water droplets on the membrane surface were blown away. The membrane was then wetted with 40 mL of trimesoyl chloride-n-hexane solution for 1 min, the excess solution was poured off, and the water droplets on the surface were blown away. Finally, the membrane was transferred to a 70 °C forced-air drying oven and heated for 10 min for further thermosetting.

[0097] The polyimide-polyamide composite membrane prepared in Comparative Example 3 had a carbon dioxide permeability of 25.62 GPU and a water vapor permeability of 1873.05 g / (m²). 2•24h).

[0098] Comparative Example 4

[0099] (1) 5.2448 g of p-phenylenediamine was placed in a three-necked flask, and 180 mL of N,N-dimethylformamide was added under a nitrogen atmosphere. The mixture was stirred at room temperature until completely dissolved. 15.6277 g of 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added in portions. The beaker and inner wall were rinsed with 180 mL of N,N-dimethylformamide, and the mixture was stirred to generate a 70 mg / mL polyamic acid solution. The solution was then diluted to 46 mg / mL and transferred to a polytetrafluoroethylene hydrothermal reactor for solvothermal polymerization. The mixture was placed in an oven at 180 °C for 6 h for high-temperature condensation and high-pressure crystallization to obtain polyimide nanoflower particles. Finally, the product was repeatedly washed with N,N-dimethylformamide and ethanol, dried in an oven, and collected for later use to obtain polyimide nanoflowers with an imidization degree of 92%.

[0100] A membrane fabrication process was employed, in which particles were added between the aqueous and oil phase monomers. A polytetrafluoroethylene (PTFE) plate-frame was used to fix the polysulfone ultrafiltration membrane. A 20 g / L m-phenylenediamine-water solution and a 1 g / L trimesoyl chloride-n-hexane solution were prepared. 2 mg of polyimide nanoflowers were weighed and added to 20 mL of n-hexane, and dispersed by sonication for 10 min. The polysulfone substrate was then immersed in 40 mL of the m-phenylenediamine-water solution for 3 min, excess solution was discarded, and water droplets on the membrane surface were blown away. The membrane was then immersed in the polyimide-n-hexane solution for 5 min, discarded, and water droplets on the surface were blown away. Finally, the membrane was immersed in 40 mL of the trimesoyl chloride-n-hexane solution for 1 min, excess solution was discarded, water droplets on the surface were blown away, and the membrane was transferred to a 70°C forced-air drying oven and heated for 10 min for further thermosetting.

[0101] The polyimide-polyamide composite membrane prepared in Comparative Example 4 had a carbon dioxide permeability of 105.18 GPU and a water vapor permeability of 1969.45 g / (m²). 2 •24h).

[0102] Comparative Example 5

[0103] The commercial paper membrane was tested and found to have a carbon dioxide permeability of 9.5 × 10⁶ GPU and a water vapor permeability of 2237.83 g / (m²). 2 (24h), heat exchange efficiency 97.52%, enthalpy exchange efficiency 72.47%.

[0104] The moisture permeability and gas barrier properties of the layered polyimide nanoflower-polyamide composite membrane are shown in Table 1.

[0105] Table 1

[0106]

[0107] The total heat exchange efficiency of the layered polyimide nanoflower-polyamide composite membrane and the commercial paper membrane is shown in Table 2.

[0108] Table 2

[0109]

Claims

1. The application of layered polyimide nanoflower-polyamide composite membranes in moisture permeability, gas barrier properties, and heat recovery, characterized in that... The sheet-like polyimide nanoflower-polyamide composite membrane includes a polymer porous support layer, a polyamide active separation layer, and sheet-like polyimide nanoflowers. The nanoflowers in the sheet-like polyimide nanoflowers participate in the cross-linking polymerization of polyamide and are embedded in the surface of the polyamide active separation layer. The preparation of the layered polyimide nanoflowers includes: (1) Place the aromatic diamine monomer in a container, add an aprotic polar solvent under a nitrogen atmosphere, stir, and after complete dissolution, add the aromatic dianhydride monomer in portions, rinse the beaker and inner wall with an aprotic polar solvent, and stir for 8 to 24 hours to generate a polyamic acid solution. (2) The polyamic acid solution prepared in step (1) is transferred to a hydrothermal reactor for solvothermal polymerization. The product is placed in an oven at 140-180°C for 2-12 hours for high-temperature condensation and high-pressure crystallization. The product is repeatedly washed with a non-protic polar solvent and ethanol, dried in an oven and collected to obtain polyimide nanoflower particles.

2. The application as described in claim 1, characterized in that, The preparation of the layered polyimide nanoflowers further includes: (3) soaking the polyimide nanoflower particles obtained in step (2) in 0.1-0.5 mol / L KOH or NaOH solution for 6-48 h for ring-opening modification; and treating the particles in a vacuum drying oven at 250-300˚C for 3-15 h to complete the imidization of the particles, thereby obtaining imidized nanoflower particles.

3. The application as described in claim 1, characterized in that, The polymer porous support layer is one of polyester, polyolefin, and nylon, and its surface is coated with a polysulfone layer.

4. The application as described in claim 1, characterized in that, The polyamide active separation layer is prepared by successively impregnating the surface of a polymer porous support layer with aqueous monomers and oil monomers, followed by interfacial polymerization and thermosetting.

5. The application as described in claim 1, characterized in that, The layered polyimide nanoflowers described herein have a particle size of 1.5~3.5 μm and a specific surface area of ​​10~300 m². 2 / g.

6. A method for preparing a layered polyimide nanoflower-polyamide composite film, characterized in that, Includes the following steps: (1) Place the aromatic diamine monomer in a container, add an aprotic polar solvent under a nitrogen atmosphere, stir, and after complete dissolution, add the aromatic dianhydride monomer in portions, rinse the beaker and inner wall with an aprotic polar solvent, and stir for 8 to 24 hours to generate a polyamic acid solution. (2) The polyamic acid solution prepared in step (1) is transferred to a hydrothermal reactor for solvothermal polymerization. The product is placed in an oven at 140-180°C for 2-12 hours for high-temperature condensation and high-pressure crystallization. The product is repeatedly washed with aprotic polar solvent and ethanol, dried in an oven and collected to obtain polyimide nanoflower particles. (3) The polyimide nanoflower particles obtained in step (2) are subjected to ring-opening modification by soaking in 0.1-0.5 mol / L KOH or NaOH solution for 6-48 h; the particles are imidized by treating in a vacuum drying oven at 250-300˚C for 3-15 h to obtain imidized nanoflower particles. (4) Wet the surface of the polymer porous support layer with the aqueous monomer solution, pour off the excess solution, and blow away the water droplets on the membrane surface; (5) Weigh the polyimide nanoflower particles from step (2) or the imidized nanoflower particles obtained in step (3), and disperse them uniformly in the oil phase monomer solution, and sonicate to obtain a solution. (6) Contact the solution obtained in step (5) with the surface of the film formed in step (4) so ​​that the interfacial polymerization and nanoflower loading are carried out simultaneously. Pour off the excess solution, blow away the water droplets on the surface, and transfer it to a forced-air drying oven for heating and curing to obtain a layered polyimide nanoflower-polyamide composite film.

7. The method for preparing the layered polyimide nanoflower-polyamide composite film according to claim 6, characterized in that, In step (1), the aromatic diamine is selected from one or more of m-phenylenediamine, p-phenylenediamine, 2,4,6-trimethylm-phenylenediamine, 3,5-diaminobenzoic acid, diaminodiphenyl ether, and diaminobenzidine; The aromatic dianhydride is selected from one or more of dimethyltetracarboxylic dianhydride, pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, hexafluorodianhydride, diphenyl ether tetracarboxylic dianhydride, and biphenyl ketone tetracarboxylic dianhydride; The aprotic polar solvent is one or more of N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.

8. The method for preparing the layered polyimide nanoflower-polyamide composite film according to claim 6, characterized in that, In step (4), the aqueous monomer in the aqueous monomer solution is one or more of m-phenylenediamine, p-phenylenediamine, piperazine, o-phenylenediamine, diethylenetriamine, and triethylenetetramine; the solvent is water.

9. The method for preparing the layered polyimide nanoflower-polyamide composite film according to claim 6, characterized in that, In step (5), the oil phase monomer in the oil phase monomer solution is one or more of pyromellitic methyl methacrylate, isophthaloyl chloride, terephthaloyl chloride, and polysulfonyl chloride; the solvent of the oil phase monomer solution is one or more of n-hexane, n-heptane, n-octane, n-dodecane, isododecane, and isohexadecane.

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