Preparation method of polyimide / amino-functionalized talcum powder mixed matrix membrane
Amino-functionalized montmorillonite powder is introduced into polyimide membranes to address issues of high cost, poor dispersion, and low mechanical strength, enhancing CO2 selectivity and permeability by forming hydrogen bonds, thus improving the membrane's mechanical properties and CO2 separation efficiency.
Patent Information
- Application Number
- CN202510481735.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-17
- Publication Date
- 2025-07-15
AI Technical Summary
Existing polyimide mixed matrix membranes face challenges such as high filler cost, poor dispersion, filler agglomeration, and low mechanical strength, hindering their industrial application in CO2 separation.
Introducing amino-functionalized montmorillonite powder into polyimide membranes to form a mixed matrix membrane, leveraging the formation of hydrogen bonds between the amino groups on the montmorillonite surface and the polyimide chains to enhance compatibility and dispersion, thereby improving mechanical properties and CO2 adsorption.
The amino-functionalized montmorillonite powder enhances the mechanical strength and CO2 permeability of the mixed matrix membrane, overcoming the 'trade-off' effect, with improved CO2 selectivity and permeability due to the formation of hydrogen bonds and uniform dispersion.
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Figure CN120305843A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of polyimide film preparation, and particularly relates to a preparation method of a polyimide / amino-functionalized talc mixed matrix membrane. Background Art
[0002] In recent years, with the large-scale combustion of fossil fuels, the excessive concentration of atmospheric carbon dioxide globally has led to an increasingly severe greenhouse effect. Therefore, it is imperative to develop energy-saving and efficient CO2 separation technologies. Common CO2 separation methods include adsorption, amine absorption, and membrane separation. As an efficient green CO2 separation technology, membrane separation shows great advantages in terms of equipment floor area, environmental hazards, energy consumption, and cost, and has great application prospects.
[0003] Polyimide (PI) is a type of polymer with imide rings in its main chain, having high thermal stability, chemical stability, high mechanical properties, and easy structural regulation. The gas separation membranes prepared therefrom exhibit good gas permeability. At the same time, by adjusting the structure of polyimide molecules, the arrangement state of molecular chains in the polyimide gas separation membrane can be changed, thereby changing the free volume of the membrane material, and thus the directional regulation of CO2 permeability and selectivity can be achieved (Progress in Polymer Science, 2019, 91, 80 - 125). However, when separating CO2, polyimide membranes are often restricted by the "trade-off" effect, and it is difficult to simultaneously consider their CO2 permeability and selectivity. To solve the above problems, some fillers with good adsorption and separation effects on CO2 are introduced into the polyimide membrane to form a polyimide mixed matrix membrane, thereby further improving the CO2 gas permeation performance (Chemical Engineering Journal, 2024, 152912). However, there are certain problems in the preparation process of polyimide mixed matrix membranes. For example, high filler cost, poor dispersibility, easy agglomeration, low membrane mechanical strength, etc., resulting in the difficulty of industrial application of polyimide mixed matrix membranes. Summary of the Invention
[0004] In view of the above technical problems existing in the preparation of polyimide mixed matrix membranes, such as high filler cost, poor filler dispersibility, easy agglomeration of fillers, and low mechanical strength, the present invention provides a method for preparing a polyimide / amino-functionalized talc mixed matrix membrane. This method involves doping low-cost amino-functionalized talc into the polyimide membrane to obtain a polyimide / amino-functionalized talc mixed matrix membrane. By forming hydrogen bond networks between -NH2 on the surface of amino-functionalized talc and C=O in the polyimide chain segments, the interfacial compatibility between the organic and inorganic phases is effectively improved. As a result, the amino-functionalized talc is uniformly dispersed in the polyimide membrane matrix. This not only improves the stress on the membrane and enhances its mechanical properties but also the specific adsorption of CO2 molecules by the amino groups on the talc surface enhances the CO2 permeability of the mixed matrix membrane.
[0005] The object of the present invention is achieved through the following technical solutions:
[0006] A method for preparing a polyimide / amino-functionalized talc mixed matrix membrane according to the present invention includes the following steps:
[0007] (1) Preparation of amino-functionalized talc
[0008] Disperse 0.5 - 2 g of talc nanoparticles into 50 - 100 mL of an organic solvent, then add 5 - 10 mL of a silane coupling agent. Under the protection of an inert gas, stir at 60 - 100 °C for 12 - 48 h. Then wash the solid particles with the organic solvent, filter by suction, and place them in a drying oven at 60 - 100 °C for 8 - 24 h to obtain amino-functionalized talc.
[0009] (2) Synthesis of polyimide
[0010] Dissolve 0.01 - 0.02 mol of diamine in 20 - 40 mL of an organic solvent, then add 0.01 - 0.024 mol of dianhydride to the above mixed solution. Under the protection of an inert gas, stir at 0 - 15 °C for 8 - 24 h to obtain polyamic acid. Add 0.03 - 0.06 mol of a dehydrating agent and 0.01 - 0.02 mol of a catalyst to the above polyamic acid solution, react for 12 - 48 h, and then pour it into 30 - 100 mL of a poor solvent to precipitate, obtaining polyimide resin.
[0011] (3) Preparation of the mixed matrix membrane
[0012] Add 0.05 - 0.12 g of the amino-functionalized talcum powder obtained in step (1) and 0.45 - 1.08 g of the polyimide resin obtained in step (2) into 10 - 30 mL of an organic solvent, stir for 6 - 24 h, and obtain a polyimide / amino-functionalized talcum powder casting solution; evenly cast 4 - 10 g of the casting solution in a super-flat petri dish, and place it in a vacuum drying oven at 60 - 120 °C for heat treatment for 8 - 24 h to obtain a polyimide / amino-functionalized talcum powder mixed matrix membrane.
[0013] Further, the organic solvent in step (1) is one of anhydrous methanol, anhydrous ethanol, and anhydrous toluene.
[0014] Further, the inert gas in steps (1) and (2) is one of nitrogen, argon, and helium.
[0015] Further, the silane coupling agent in step (1) is selected from one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane.
[0016] Further, the dianhydride in step (2) is one of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and 4,4'-biphenylether dianhydride.
[0017] Further, the diamine is one of 4,4'-diaminodiphenyl disulfide, 2,2',5,5'-tetrachlorobenzidine, and 2,2'-bis(trifluoromethyl)diaminobiphenyl.
[0018] Further, the dehydrating agent in step (2) is one of acetic anhydride and trifluoroacetic anhydride, and the catalyst is one of triethylamine and pyridine.
[0019] Further, the poor solvent in step (2) is one of methanol, ethanol, and deionized water.
[0020] Further, the catalyst in step (2) is one of triethylamine and pyridine.
[0021] Further, the organic solvent in steps (2) and (3) is one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.
[0022] The beneficial effects of the present invention are as follows:
[0023] By introducing amino-functionalized talc into the polyimide membrane, abundant CO2-affinity sites are constructed within the membrane. The reversible chemical interaction between the amino group and CO2 molecules significantly enhances the selective adsorption ability of the membrane material for CO2. Meanwhile, the layered structure of talc provides a fast transport channel for CO2, effectively breaking through the "trade-off" effect limitation of traditional polymer membranes. The amino group of the amino-functionalized talc forms a hydrogen bond with the polyimide matrix. This interfacial interaction mechanism significantly improves the filler-matrix compatibility, enabling the uniform dispersion of talc nanoparticles in the polymer. As a rigid filler, the addition of amino-functionalized talc can significantly improve the tensile strength of the polyimide membrane. This method is simple, low-cost, and easy to operate, and is suitable for industrial scale-up production. Description of the Drawings
[0024] Figure 1 is the SEM surface morphology diagram of the polyimide / amino-functionalized talc mixed matrix membrane in the present invention;
[0025] Figure 2 is the SEM cross-sectional morphology diagram of the polyimide / amino-functionalized talc mixed matrix membrane in the present invention;
[0026] Figure 3 is the EDX diagram of the polyimide / amino-functionalized talc mixed matrix membrane in the present invention;
[0027] Figure 4 is the FTIR diagram of the polyimide / amino-functionalized talc mixed matrix membrane in the present invention;
[0028] Figure 5 is the XRD diagram of the polyimide / amino-functionalized talc mixed matrix membrane in the present invention;
[0029] Figure 6 is the DSC diagram of the polyimide / amino-functionalized talc mixed matrix membrane in the present invention. Detailed Embodiments
[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the present invention will be described in detail below with reference to the drawings and embodiments.
[0031] Example 1
[0032] (1) Preparation of amino-functionalized talc
[0033] Disperse 0.5 g of talc nanoparticles into 50 mL of absolute ethanol, then add 5 mL of 3-aminopropyltrimethoxysilane. Under nitrogen protection, stir at 60 °C for 12 h, then wash the solid particles with absolute ethanol, filter by suction, and place them in a drying oven at 60 °C for 8 h to obtain amino-functionalized talc.
[0034] (2) Synthesis of polyimide
[0035] Dissolve 0.01 mol of 4,4'-diaminodiphenyl disulfide in 20 mL of N-methylpyrrolidone, and then add 0.01 mol of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride to the above mixed solution. Under nitrogen protection, stir at 0 °C for 8 h to obtain polyamic acid. Add 0.03 mol of acetic anhydride and 0.01 mol of triethylamine to the above polyamic acid solution. After reacting for 12 h, pour it into 30 mL of methanol to precipitate, and obtain polyimide resin.
[0036] (3) Preparation of mixed matrix membrane
[0037] Add 0.05 g of amino-functionalized talc powder obtained in step (1) and 0.45 g of polyimide resin obtained in step (2) to 10 mL of N-methylpyrrolidone, stir for 6 h to obtain a polyimide / amino-functionalized talc casting solution. Pour 4 g of the casting solution evenly onto a super-flat petri dish, and place it in a vacuum drying oven at 60 °C for heat treatment for 8 h to obtain a polyimide / amino-functionalized talc mixed matrix membrane.
[0038] Example 2
[0039] (1) Preparation of amino-functionalized talc powder
[0040] Disperse 1 g of talc nanoparticles into 75 mL of anhydrous methanol, and then add 7 mL of 3-aminopropyltriethoxysilane. Under argon protection, stir at 80 °C for 24 h. Wash the solid particles with anhydrous methanol, filter by suction, and place them in a drying oven at 80 °C for drying for 12 h to obtain amino-functionalized talc powder.
[0041] (2) Synthesis of polyimide
[0042] Dissolve 0.015 mol of 2,2',5,5'-tetrachlorobenzidine in 30 mL of N,N-dimethylformamide, and then add 0.015 mol of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride to the above mixed solution. Under argon protection, stir at 7 °C for 12 h to obtain polyamic acid. Add 0.04 mol of trifluoroacetic anhydride and 0.015 mol of triethylamine to the above polyamic acid solution. After reacting for 24 h, pour it into 60 mL of ethanol to precipitate, and obtain polyimide resin.
[0043] (3) Preparation of mixed matrix membrane
[0044] Add 0.08 g of amino-functionalized talc powder obtained in step (1) and 0.75 g of polyimide resin obtained in step (2) into 20 mL of N,N-dimethylformamide. After stirring for 18 h, a polyimide / amino-functionalized talc powder casting solution is obtained. Pour 6 g of the casting solution evenly onto a super-flat petri dish and place it in a vacuum drying oven at 90 °C for heat treatment for 18 h to obtain a polyimide / amino-functionalized talc powder mixed matrix membrane.
[0045] Example 3
[0046] (1) Preparation of amino-functionalized talc powder
[0047] Disperse 2 g of talc nanoparticles into 100 mL of anhydrous toluene, then add 10 mL of 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane. Under the protection of helium gas, stir at 100 °C for 48 h. Then wash the solid particles with anhydrous toluene, filter by suction, and place them in a drying oven at 100 °C for drying for 24 h to obtain amino-functionalized talc powder.
[0048] (2) Synthesis of polyimide
[0049] Dissolve 0.02 mol of 2,2'-bis(trifluoromethyl)diaminobiphenyl in 40 mL of dimethyl sulfoxide, and then add 0.024 mol of 4,4'-oxydiphthalic dianhydride to the above mixed solution. Under the protection of nitrogen gas, stir at 15 °C for 24 h to obtain polyamic acid. Add 0.06 mol of trifluoroacetic anhydride and 0.02 mol of pyridine to the above polyamic acid solution. After reacting for 48 h, pour it into 100 mL of deionized water to precipitate, and obtain polyimide resin.
[0050] (3) Preparation of mixed matrix membrane
[0051] Add 1.08 g of polyimide resin obtained in step (2) and 0.12 g of amino-functionalized talc powder obtained in step (1) into 30 mL of N,N-dimethylformamide. After stirring for 24 h, a polyimide / amino-functionalized talc powder casting solution is obtained. Pour 10 g of the casting solution evenly onto a super-flat petri dish and place it in an oven at 120 °C for heat treatment to obtain a polyimide / amino-functionalized talc powder mixed matrix membrane.
[0052] Add 0.12 g of amino-functionalized talc powder obtained in step (1) and 1.08 g of polyimide resin obtained in step (2) into 30 mL of dimethyl sulfoxide. After stirring for 24 h, a polyimide / amino-functionalized talc powder casting solution is obtained. Pour 10 g of the casting solution evenly onto a super-flat petri dish and place it in a vacuum drying oven at 120 °C for heat treatment for 24 h to obtain a polyimide / amino-functionalized talc powder mixed matrix membrane.
[0053] Comparative example
[0054] The difference between this comparative example and Example 1 is that in step (3), the amino-functionalized talcum powder prepared in step (1) was not added.
[0055] The prepared polyimide / amino-functionalized talcum powder mixed matrix membrane was placed in a tensile tester for testing, and the tensile property results are shown in Table 1. As can be seen from Table 1, the polyimide / amino-functionalized talcum powder mixed matrix membrane prepared by this invention has excellent mechanical properties. This is because the addition of amino-functionalized talcum powder as a rigid filler hinders the movement of polyimide molecular chains during the stretching process, resulting in an increase in the tensile strength of the polyimide / amino-functionalized talcum powder mixed matrix membrane.
[0056] Table 1 Tensile properties of polyimide / amino-functionalized talcum powder mixed matrix
[0057]
[0058]
[0059] The polyimide / amino-functionalized talcum powder mixed matrix membrane was placed in a gas permeation tester, and the gas permeation performance was tested under the conditions of a temperature of 35°C and a permeation pressure of 2 Bar. The test results are shown in Table 2. As can be seen from Table 2, the polyimide / amino-functionalized talcum powder mixed matrix membrane prepared by this invention has good gas separation performance. After incorporating amino-functionalized talcum powder, the CO2 / CH4 gas permeation performance of the mixed matrix membrane is significantly improved. This is mainly because the introduction of amino-functionalized talcum powder causes a change in the intermolecular chain structure within the polyimide membrane, which not only increases the chain rigidity of the polymer membrane but also enlarges the free volume, promoting the movement and diffusion of CO2 and improving the permeation performance of the polyimide membrane. In addition, a large number of -NH2 present on the surface of amino-functionalized talcum powder have basicity and can specifically adsorb the acidic gas CO2, contributing to the selective separation of CO2.
[0060] Table 2 Gas separation performance of polyimide / amino-functionalized talcum powder mixed matrix membrane
[0061]
[0062] It can be seen from Figure 1 that the surface of the polyimide / amino-functionalized talcum powder mixed matrix membrane has a complete dense structure, and no obvious holes or needle-like defects are observed.
[0063] It can be seen from Figure 2It can be seen that the thickness of the polyimide / amino-functionalized talc mixed matrix membrane is about 100 μm, and there is a non-penetrating loose structure. These changes in the microstructure are caused by the introduction of amino-functionalized talc, which is beneficial to improving the gas permeability of the membrane.
[0064] It can be Figure 3 seen that elements C, O, F, S, N, Si, and Mg are evenly distributed in the polyimide / amino-functionalized talc mixed matrix membrane, indicating that amino-functionalized talc has been introduced into the polyimide membrane.
[0065] It can be Figure 4 seen that the characteristic diffraction peaks of amino-functionalized talc appear at 2θ = 9.5° and 2θ = 28.6°. After comparison, it is found that these two characteristic diffraction peaks also appear in the polyimide / amino-functionalized talc mixed matrix membrane, indicating that amino-functionalized talc has been successfully incorporated into the polyimide matrix.
[0066] It can be Figure 5 seen that the polyimide / amino-functionalized talc mixed matrix membrane retains the characteristic absorption peaks of polyimide at 1736 cm-1 (imide C=O stretching vibration) and 1388 cm-1 (C-N stretching vibration). Moreover, characteristic peaks of amino-functionalized talc appear at 3675 cm-1 (Mg-OH) and 1018 cm-1 (Si-O), which is consistent with the EDX elemental distribution ( Figure 3 ) and the XRD analysis results ( Figure 4 ).
[0067] It can be Figure 6 seen that compared with the comparative example, the glass transition temperature of the polyimide / amino-functionalized talc mixed matrix membrane is significantly increased. This is because the introduction of the filler reduces the flexibility and mobility of the PI chains and increases the rigidity of the chain segments.
[0068] The components not described in detail in this application are all conventional existing technologies and will not be elaborated here.
[0069] It can be understood that the above specific description of the present invention is only for explaining the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those of ordinary skill in the art should understand that the present invention can still be modified or equivalently replaced to achieve the same technical effects; as long as it meets the usage requirements, it is within the protection scope of the present invention.
Claims
1. A method for preparing a polyimide / amino-functionalized talc mixed matrix membrane, characterized in that, It includes the following steps: (1) Prepare amino-functionalized talc powder Disperse 0.5 - 2 g of talc nanoparticles into 50 - 100 mL of an organic solvent, then add 5 - 10 mL of a silane coupling agent. Under the protection of an inert gas, stir at 60 - 100 °C for 12 - 48 h. Then wash the solid particles with the organic solvent, filter by suction, and place them in an oven at 60 - 100 °C for drying for 8 - 24 h to obtain amino-functionalized talc powder; (2) Synthesize polyimide Dissolve 0.01 - 0.02 mol of diamine in 20 - 40 mL of an organic solvent, then add 0.01 - 0.024 mol of dianhydride to the above mixed solution. Under the protection of an inert gas, stir at 0 - 15 °C for 8 - 24 h to obtain polyamic acid; Add 0.03 - 0.06 mol of a dehydrating agent and 0.01 - 0.02 mol of a catalyst to the above polyamic acid solution, react for 12 - 48 h, and then pour it into 30 - 100 mL of a poor solvent to precipitate, obtaining polyimide resin; (3) Prepare a mixed matrix membrane Add 0.05 - 0.12 g of the amino-functionalized talc powder obtained in step (1) and 0.45 - 1.08 g of the polyimide resin obtained in step (2) to 10 - 30 mL of an organic solvent, stir for 6 - 24 h to obtain a polyimide / amino-functionalized talc powder casting solution; Pour 4 - 10 g of the casting solution evenly onto a super-flat surface dish, and place it in a vacuum drying oven at 60 - 120 °C for heat treatment for 8 - 24 h to obtain a polyimide / amino-functionalized talc powder mixed matrix membrane.
2. The preparation method of a polyimide / amino-functionalized talc powder mixed matrix membrane according to claim 1, characterized in that: The organic solvent in step (1) is one of anhydrous methanol, anhydrous ethanol, and anhydrous toluene.
3. The preparation method of a polyimide / amino-functionalized talc powder mixed matrix membrane according to claim 1, characterized in that: The inert gas in steps (1) and (2) is one of nitrogen, argon, and helium.
4. The preparation method of a polyimide / amino-functionalized talc mixed matrix membrane according to claim 1, characterized in that: The silane coupling agent selected in step (1) is one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane.
5. The preparation method of a polyimide / amino-functionalized talc powder mixed matrix membrane according to claim 1, characterized in that: The dianhydride in step (2) is one of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and 4,4'-oxydiphthalic anhydride.
6. The preparation method of a polyimide / amino-functionalized talc powder mixed matrix membrane according to claim 1, characterized in that: The diamine is one of 4,4'-diaminodiphenyl disulfide, 2,2',5,5'-tetrachlorobenzidine, and 2,2'-bis(trifluoromethyl)benzidine.
7. The preparation method of a polyimide / amino-functionalized talc powder mixed matrix membrane according to claim 1, characterized in that: The dehydrating agent in step (2) is one of acetic anhydride and trifluoroacetic anhydride, and the catalyst is one of triethylamine and pyridine.
8. The preparation method of a polyimide / amino-functionalized talc hybrid matrix membrane according to claim 1, characterized in that: The poor solvent in step (2) is one of methanol, ethanol, and deionized water.
9. The preparation method of a polyimide / amino-functionalized talc powder mixed matrix membrane according to claim 1, characterized in that: The catalyst in step (2) is one of triethylamine and pyridine.
10. The preparation method of a polyimide / amino-functionalized talc hybrid matrix membrane according to claim 1, characterized in that: The organic solvents in steps (2) and (3) are one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.