Ultraviolet radiation induced polyMOF mixed matrix membrane as well as preparation method and application thereof

Abstract

The invention discloses an ultraviolet radiation induced polyMOF mixed matrix membrane and a preparation method and application thereof.The polyMOF mixed matrix membrane comprises a polymer matrix and MOF crystals growing in situ, and an MOF organic ligand is covalently grafted to a molecular chain of the polymer matrix through a thiol-ene click chemical reaction; the MOF crystal grows in situ by taking an MOF organic ligand as a nucleation site and is embedded into the polymer matrix. According to the invention, an organic ligand structure is introduced to a polymer cross-linked network, sulfydryl is introduced to an organic ligand through a sulfydryl-vinyl click chemical reaction, and the network structure and free volume of a polymer chain can be reasonably and orderly regulated and controlled while polymer chain cross-linking is realized; furthermore, MOF crystals are synthesized in situ by utilizing a dissolution heat method, so that the polyMOF mixed matrix membrane with high interface bonding force is obtained.

Description

Technical Field

[0001] This invention relates to the field of matrix membrane preparation technology, and in particular to an ultraviolet irradiation-induced polyMOF hybrid matrix membrane, its preparation method, and its application. Background Technology

[0002] Hybrid matrix membranes combine the ease of preparation of polymer membranes with the high performance of inorganic membranes, overcoming the "trade-off" relationship inherent in polymer membranes. However, traditional membrane fabrication methods (physical doping and chemical crosslinking) are difficult to scale up and controllably. Currently, the core challenges in preparing hybrid matrix membranes lie in the uniformity of filler dispersion and the control of membrane structure and interfacial compatibility. While small-volume (<1 L) filler-polymer solutions can be dispersed using ultrasound and high-speed stirring in laboratory settings, large-scale production (>100 L) suffers from low solution mixing efficiency, easy sedimentation or secondary agglomeration of the filler, resulting in poor performance consistency across batches. Therefore, the core advantage of the polyMOF hybrid matrix membrane preparation method is that it addresses the two major pain points of traditional MOF hybrid matrix membranes—interfacial incompatibility and poor stability—through polymer modification, while also allowing for flexible control of separation performance.

[0003] Acrylate (H₂C=CH-COO-) or methacrylate (H₂C=CH(CH₃)-COO-) groups can undergo click chemistry reactions with thiols (-SH), and this is one of the most widely used reaction types in thiol-alkene click chemistry. The core reaction relies on the nucleophilic addition of the thiol to the carbon-carbon double bond, and is characterized by mild reaction conditions and high selectivity. This reaction does not require high temperature or pressure; it can proceed rapidly at room temperature (25-40 °C) or under ultraviolet light (UV, 365 nm) irradiation, and produces almost no byproducts.

[0004] Patent CN 120381765 A discloses an in-situ grown MOFs mixed matrix membrane, its method, and its application, including the following steps: adding a Zn source and 2-methylimidazole to a solvent for a hydrothermal reaction to obtain Polymer-ZIF-8; mixing Polymer-ZIF-8 with a diluent, and then sequentially heating, mixing, and cooling to obtain a Polymer-ZIF-8 / diluent homogeneous bulk; and post-processing the Polymer-ZIF-8 / diluent homogeneous bulk to obtain the MOFs mixed matrix membrane; the Zn source is a zinc ion polymer, and this method overcomes the interfacial compatibility problem in the mixed matrix membrane. Patent CN 106621864 B discloses a MOFs-crosslinked polyethylene glycol diacrylate mixed matrix membrane, its preparation, and its application. Polyethylene glycol diacrylate (PEGDA) is selected as the matrix membrane material, and metal-organic frameworks (MOFs) are chosen as fillers. The MOFs-crosslinked polyethylene glycol diacrylate mixed matrix membrane (MOFs-XLPEGDA) is prepared by UV crosslinking and curing under the induction of a photoinitiator. This type of mixed matrix membrane exhibits significant separation performance for CO2 / N2 and CO2 / CH4 mixed gases (PCO2 > 160 Barrer, αCO2 / N2 > 70, αCO2 / CH4 > 40). Compared to pure crosslinked polyethylene glycol diacrylate membranes, the prepared MOFs / crosslinked polyethylene glycol diacrylate mixed matrix membrane has higher CO2 gas permeability and separation selectivity, and can be applied to the purification of flue gas and natural gas. However, this patent does not mention the strengthening of the interfacial interaction between the filler and the polymer. Patent CN 119971792 A discloses a metal-organic framework hybrid matrix membrane, its preparation method, and its application. The hybrid matrix membrane uses water-stable metal-organic framework material Zn-bzc-2CH3 synthesized by solvothermal method as the dispersed phase and cross-linked polyethylene glycol XLPEO as the continuous phase of the polymer matrix. It is prepared by ultraviolet cross-linking polymerization. Zn-bzc-2CH3 material has kinetic sieving ability for propylene / propane. Therefore, the hybrid matrix membrane exhibits enhanced propylene / propane separation performance. Patent CN120550631 A discloses an XLPEO / MIL@TAPB-DMTPCOF hybrid matrix membrane, its preparation method, and its application. The method involves preparing a MIL@TAPB-DMTP-COF core-shell material using a dual-ligand assisted synthesis strategy. This material is then incorporated into a mixture of polyethylene glycol diacrylate and polyethylene glycol diacrylate and dispersed uniformly to form a casting solution. The two types of PEO polymers are cross-linked by ultraviolet irradiation to form an XLPEO / MIL@TAPB-DMTP-COF hybrid matrix membrane, which exhibits excellent CO2 / N2 separation performance.

[0005] The membranes prepared by the aforementioned invention patents are all homogeneous mixed matrix membranes, which significantly limit their pilot-scale / large-scale preparation and industrial applications. Therefore, it is necessary to improve traditional mixed matrix membranes and their preparation methods. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide an ultraviolet irradiation-induced polyMOF mixed matrix membrane, its preparation method, and its application. This invention introduces organic ligand structures into the polymer crosslinking network, utilizes thiol-vinyl click chemistry to achieve polymer chain crosslinking while rationally and orderly controlling the network structure and free volume of the polymer chains, and further utilizes a solubilothermic method to synthesize MOF crystals in situ, thereby obtaining a polyMOF mixed matrix membrane with high interfacial bonding strength.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A UV-induced polyMOF hybrid matrix film includes a polymer matrix and in-situ grown MOF crystals. The polymer matrix has MOF organic ligands covalently grafted onto its molecular chains via a thiol-alkene click chemistry reaction. The MOF crystals are in-situ grown and embedded in the polymer matrix using the MOF organic ligands as nucleation sites.

[0009] A method for preparing a polyMOF hybrid matrix membrane induced by ultraviolet irradiation includes the following steps:

[0010] S1. Preparation of acrylate-containing polymers: A monomer with acrylate groups is grafted onto a polymer with active functional groups in a solvent to obtain a modified polymer solution containing acrylate groups.

[0011] S2. Introduction of photoinduced ligands: If the organic ligand itself contains a thiol group, a thiol-containing organic ligand and a photoinitiator can be added to the modified polymer solution, and a thiol-alkene click chemical reaction can be carried out under ultraviolet light irradiation to obtain a cross-linked polymer precursor containing an organic ligand structure; if the organic ligand itself does not contain a thiol group, a thiol-alkene click chemical reaction can be carried out between an alkene-containing ligand and a small molecule containing multiple thiol groups to first obtain a thiol-containing organic ligand, and then repeat the above steps.

[0012] S3. In-situ synthesis of polyMOF: Metal salts are added to the cross-linked polymer precursor and a solvothermal reaction is carried out to induce the coordination of metal ions with organic ligands on the polymer chain. A mixture containing polyMOF particles and further cross-linked polymer network is synthesized in situ. After washing and centrifugation, polyMOF mixed matrix material is obtained.

[0013] S4. Film formation and curing: The polyMOF mixed matrix material is dispersed in a solvent to prepare a coating solution, which is then coated on the surface of the base film and dried to obtain the polyMOF mixed matrix film.

[0014] Preferably, in step S1, the active functional group is one or more of hydroxyl, carboxyl, or amino groups;

[0015] The polymer is one or more of hydroxyl-terminated siloxanes, amino-terminated siloxanes, side-chain aminosiloxanes, polyethyleneimine, sodium alginate, polyvinyl alcohol, chitosan, and polyether block amides. The molecular weight of hydroxyl-terminated siloxane and amino-terminated siloxane polymers is 500-10000, and the molecular weight of side-chain aminosiloxane polymers is 10000-50000.

[0016] The monomers containing acrylate groups are one or more of acryloyl chloride, acrylic acid, glycidyl acrylate, 4-hydroxybutyl acrylate glycidyl ether, and acrylic anhydride;

[0017] The molar ratio of monomers with acrylate groups to polymers is 1:1-10:1, the reaction temperature is 30-100 ℃, and the reaction time is 3-48 h;

[0018] The mass concentration of acrylate-containing siloxanes is 0.5 wt%-50 wt%.

[0019] Preferably, in step S2, the thiol-containing organic ligand is one or more of 2-mercaptoterephthalic acid, 2,5-dimercaptoterephthalic acid, 2,3-dimercaptoterephthalic acid, or vinylterephthalic acid modified with polythiol small molecules, 2-(allyloxy)terephthalic acid, 2,5-bis(allyloxy)terephthalic acid, and 2,5-bis(4-carboxyphenyl)-1,4-bis(allyloxy)benzene.

[0020] Preferably, in step S2 above, the thiol-containing organic ligand is obtained by a thiol-alkene click chemistry reaction between an alkene-containing organic ligand and a small molecule containing multiple thiol groups;

[0021] The small molecules containing multiple thiol groups are one or more of the following: 1,4-butanedithiol, 1,6-hexanedithiol, 2,7-dimercaptonaphthalene, 1,4-benzenedimethylthiol, 2,3-dimercaptosuccinic acid, thiol polyethylene glycol thiol, and pentaerythritol tetramercaptoacetate.

[0022] The olefin-containing organic ligand is one or more of 2-vinyl terephthalic acid, 2-(allyloxy) terephthalic acid, 2,5-bis(allyloxy) terephthalic acid, and 2,5-bis(4-carboxyphenyl)-1,4-bis(allyloxy)benzene.

[0023] Preferably, in step S2, the molar ratio of the acrylate-containing modified polymer, the mercapto-containing organic ligand, and the photoinitiator is 1:0.5:0.01-4:1:0.5;

[0024] The wavelength of ultraviolet irradiation is 300-400 nm, and the irradiation time is 0.1-6 h.

[0025] Preferably, in step S3 above, the molar ratio of the crosslinked polymer precursor to the metal ions in the metal salt is 1:0.5-2;

[0026] The metal salt is one or more of the following: zirconium salt, iron salt, aluminum salt, chromium salt, titanium salt, hafnium salt, and zinc salt;

[0027] The temperature of the solvothermal reaction is 50-200 ℃, and the reaction time is 6-36 h;

[0028] The in-situ synthesized polyMOF particles are one of polyUiO-66, polyMIL-101, polyMIL-53, polyMIL-88B(Fe), polyMOF-5, polyMIL-125, or polyUiO-68.

[0029] Preferably, in step S4 above, the solvent of the coating solution is one or more of toluene, benzene, n-heptane, ethyl acetate, dichloromethane, water, ethanol, and butanol;

[0030] The concentration of the polyMOF mixed matrix material in the coating solution is 1 wt%-70 wt%;

[0031] The base membrane has one of the following configurations: flat sheet, hollow fiber, tubular, ceramic sheet, or corrugated structure; and its material is one of the following: alumina, yttrium oxide, titanium oxide, silicon carbide, polyacrylonitrile, polycarbonate, polyvinylidene fluoride, polytetrafluoroethylene, polyethersulfone, polysulfone, or polyimide.

[0032] The drying temperature is 20-100 ℃, and the time is 0.5-12 h.

[0033] Preferably, in step S4 above, after the film-forming process is completed, the film undergoes a second ultraviolet irradiation crosslinking treatment in an N2 atmosphere.

[0034] Applications of UV-induced polyMOF hybrid matrix membranes in liquid separation, gas separation, or ion separation processes.

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

[0036] (1) This invention realizes the controllable preparation of polyMOF mixed matrix membrane with high interfacial bonding force, and solves the practical preparation process problems such as poor compatibility between external filler and polymer bulk, particle agglomeration and difficulty in dispersion, and difficulty in scale-up preparation.

[0037] (2) This invention utilizes click chemistry to selectively construct polymer chain polymers containing organic ligand structures in one step, which can then be used for the in-situ synthesis of MOF particles from different metal sources;

[0038] (3) Compared with the traditional powder and polymer blending preparation process, the preparation method of the polyMOF mixed matrix membrane of the present invention can overcome the problem of polymer solution porosity and improve the film formation rate and repeatability;

[0039] (4) The polyMOF mixed matrix membrane of the present invention can be used for the separation of systems such as aromatic hydrocarbons / alcohols, esters / alcohols, organic matter (alcohols, esters, ketones, phenols, ethers, etc.) / water, and CO2 capture. It has a wide range of applications and excellent separation effect. Attached Figure Description

[0040] Figure 1 The images show cross-sectional and surface SEM images of the polyUiO-66-SH / PDMS hybrid matrix film prepared by photoirradiation synthesis in Example 1 of this invention.

[0041] Figure 2 SEM images of UiO-66-SH particles (a) synthesized by solvothermal method in Comparative Example 1 of the present invention and polyUiO-66-SH powder (b) after solvent washing and filtration in Example 1;

[0042] Figure 3 The images show cross-sectional and surface SEM images of the UiO-66-SH / PDMS hybrid matrix film prepared by the physical doping method in Comparative Example 1 of this invention.

[0043] Figure 4 These are cross-sectional and surface SEM images of the UiO-66-SH / PDMS hybrid matrix membrane prepared by chemical cross-linking method in Comparative Example 2 of this invention;

[0044] Figure 5 This invention illustrates the effect of different membrane fabrication methods on the separation performance of a 1 wt% phenol / water system in Example 1 and Comparative Examples 1-2. Detailed Implementation

[0045] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0046] The present invention prepares a UV radiation-induced crosslinked polyMOF hybrid matrix membrane by the following steps:

[0047] Step (1) Preparation of acrylate-containing polymers: The monomers containing acrylate groups are grafted with one or more polymers with hydroxyl (or carboxyl or amino) groups of a certain molecular weight in a certain solvent at a certain mass ratio, a certain temperature and a certain time to obtain polymer monomers containing acrylate groups of different structures at a certain concentration.

[0048] The chemical formulas of different monomers containing acrylate groups are as follows:

[0049] .

[0050] The chemical formulas of common polymers containing hydroxyl (or carboxyl or amino) groups are as follows:

[0051] .

[0052] Step (2), Thiol-Al Click Chemical Reaction: An alkene-containing organic ligand and a small molecule containing multiple thiol groups are dispersed in a solvent and subjected to thiol grafting modification under UV irradiation and photoinitiator. The thiol-containing organic ligand and photoinitiator are dissolved in the polymer solution from step (1) at a specific molar ratio. The UV irradiation reaction time is controlled to obtain a polymer monomer containing the organic ligand structure. The chemical formula and reaction equation are as follows:

[0053]

[0054] Among them, R-(SH) n (n≥2) is one of 1,4-butanedithiol, 1,6-hexanedithiol, 2,7-dimercaptonaphthalene, 1,4-benzenedimethylthiol, 2,3-dimercaptosuccinic acid, mercaptopolyethylene glycol mercapto (HS-PEG-SH), and pentaerythritol tetramercaptoacetate.

[0055] Step (3) In-situ polyMOF synthesis: Add one or more different metal salts to step (2) above, and obtain a polyMOF mixture solution containing "beaded" polyMOF particles and cross-linked polymer network under a certain reaction temperature and reaction time. Soak and wash the mixture solution in methanol, and remove the supernatant by centrifugation.

[0056] Step (4) Preparation of mixed matrix separation layer: The material centrifuged in step (3) above is added back to a solvent and stirred to prepare a homogeneous coating solution of a certain concentration, and a film is formed on the surface of a base film with different configurations and materials.

[0057] After the membrane fabrication process is complete, the membrane can be quickly transferred to a nitrogen atmosphere for secondary crosslinking under UV irradiation. Then, the membrane is dried and removed at a specific temperature and time.

[0058] In step (1), the active functional group is one or more of hydroxyl, carboxyl, or amino groups; the polymer is one or more of hydroxyl-terminated siloxane, amino-terminated siloxane, side-chain aminosiloxane, polyethyleneimine, sodium alginate, polyvinyl alcohol, chitosan, and polyether block amide, and the molecular weight of the polymer is 500-50000; the monomer with acrylate groups is one or more of acryloyl chloride, acrylic acid, glycidyl acrylate, 4-hydroxybutyl acrylate glycidyl ether, and acrylic anhydride; the mass ratio of the monomer with acrylate groups to the polymer is 1:1-10:1, the reaction temperature is 30-100 ℃, and the reaction time is 3-48 h;

[0059] The mass concentration of acrylate-containing siloxanes is 0.5 wt%-50 wt%.

[0060] In step (2), if the organic ligand itself contains a thiol group, a thiol-containing organic ligand and a photoinitiator can be added to the modified polymer solution, and a thiol-alkene click chemical reaction can be carried out under ultraviolet light irradiation to obtain a cross-linked polymer precursor containing an organic ligand structure; if the organic ligand itself does not contain a thiol group, a thiol-alkene click chemical reaction can be carried out between an alkene-containing ligand and a small molecule containing multiple thiol groups to first obtain a thiol-containing organic ligand, and then repeat the above steps.

[0061] The thiol-containing organic ligand is one or more of 2-mercaptoterephthalic acid, 2,5-dimercaptoterephthalic acid, 2,3-dimercaptoterephthalic acid, or vinylterephthalic acid modified with polythiol small molecules, 2-(allyloxy)terephthalic acid, 2,5-bis(allyloxy)terephthalic acid, and 2,5-bis(4-carboxyphenyl)-1,4-bis(allyloxy)benzene. The molar ratio of the acrylate-containing modified polymer, the thiol-containing organic ligand, and the photoinitiator is 1:0.5:0.05-4:1:0.5; the wavelength of ultraviolet irradiation is 300-400 nm, and the irradiation time is 0.1-6 h. The small molecule containing multiple thiol groups is one or more of 1,4-butanedithiol, 1,6-hexanedithiol, 2,7-dimercaptonaphthalene, 1,4-benzenedimethylthiol, 2,3-dimercaptosuccinic acid, mercaptopolyethylene glycol mercapto, and pentaerythritol tetramercaptoacetate; the olefin-containing organic ligand is one or more of 2-vinyl terephthalic acid, 2-(allyloxy)terephthalic acid, 2,5-bis(allyloxy)terephthalic acid, and 2,5-bis(4-carboxyphenyl)-1,4-bis(allyloxy)benzene; the solvent is one or more of ethyl acetate, methanol, diethyl ether, acetone, benzene, water, and ethanol.

[0062] In step (3), the metal salt is one or more of zirconium salt, iron salt, aluminum salt, chromium salt, titanium salt, hafnium salt, and zinc salt; the temperature of the solvothermal reaction is 50-200 ℃, and the reaction time is 6-36 h; the polyMOF particles synthesized in situ are one of polyUiO-66, polyMIL-101, polyMIL-53, polyMIL-88B(Fe), polyMOF-5, polyMIL-125, or polyUiO-68.

[0063] In step (4), the solvent of the coating solution is one or more of toluene, benzene, n-heptane, ethyl acetate, dichloromethane, water, ethanol, and butanol; the concentration of the polyMOF mixed matrix material in the coating solution is 1 wt%-70 wt%; the configuration of the base film is one of flat plate, hollow fiber, tubular, ceramic sheet, and corrugated structure, and its material is one of alumina, yttrium oxide, titanium oxide, silicon carbide, polyacrylonitrile, polycarbonate, polyvinylidene fluoride, polytetrafluoroethylene, polyethersulfone, polysulfone, and polyimide; the drying temperature is 20-100 ℃, and the time is 0.5-12 h.

[0064] Example 1

[0065] In this embodiment, an organic ligand containing a thiol group is used. The ultraviolet radiation-induced crosslinking of the polyMOF mixed matrix membrane includes the following steps:

[0066] Acryloyl chloride and hydroxyl-terminated silicone oil were dissolved in n-heptane solution at a functional group molar ratio of 2.3:1 and refluxed at 50°C for 6 hours to form a 5 wt% acryloyloxy-terminated silicone oil solution. Then, 2-mercapto-terephthalic acid and photoinitiator 1173 were added at a polymer molar ratio of 1:0.5:0.01. UV irradiation at a wavelength of 365 nm was used for 20 minutes to achieve a terephthalic acid-containing structure in the polymer chain through a mercapto-olefin click chemistry reaction. Then, ZrCl4, in equimolar amounts with the ligands, was added, stirred, dissolved, and poured into a polytetrafluoroethylene reactor. The reaction was carried out at 120°C for 12 hours, followed by soaking, centrifugation, and washing five times. The solution was then redispersed in toluene solution and coated onto a polyacrylonitrile (PAC) substrate membrane. The membrane was dried at 70°C for 12 hours to obtain a poly(UiO-66-SH / PDMS) mixed matrix membrane, the surface and cross-section of which are shown below. Figure 1 As shown.

[0067] Example 2

[0068] In this embodiment, an organic ligand containing a thiol group is used. The ultraviolet radiation-induced crosslinking of the polyMOF mixed matrix membrane includes the following steps:

[0069] Acryloyl chloride and amino-terminated silicone oil were dissolved in n-heptane solution at a functional group molar ratio of 2.1:1 and stirred at room temperature for 4 hours to form an 8 wt% acryloyloxy-terminated silicone oil solution. Then, 2,5-dimercaptoterephthalic acid and photoinitiator 1173 were added at a polymer mass ratio of 1:0.5:0.01. The polymer chain was irradiated with UV light at a wavelength of 365 nm for 12 minutes to achieve a terephthalic acid structure in the polymer chain through a mercapto-olefin click chemistry reaction. Then, ZrCl4 with an equimolar amount of ligand was added, stirred and dissolved, and poured into a polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 hours. The mixture was soaked, centrifuged and washed 5 times, and then redispersed in toluene solution. The mixture was coated on a polyacrylonitrile film and dried at 70 °C for 12 hours to obtain a polyUiO-66-(SH)2 / PDMS mixed matrix film.

[0070] Example 3

[0071] In this embodiment, the thiol-containing organic ligand is prepared by chemical reaction of an alkenyl-containing organic ligand and a polythiol compound. The ultraviolet radiation-induced crosslinking of the polyMOF mixed matrix membrane includes the following steps:

[0072] Glycidyl acrylate and polyethyleneimine were dissolved in a mixture of water and methanol at a functional group molar ratio of 6:1 and stirred at room temperature for 6 hours to form a 2 wt% acryloyloxy-terminated polyethyleneimine solution. 2-vinyl terephthalic acid, 1,4-butanedithiol, and photoinitiator 1173 were dissolved in ethanol at 80 °C in a molar ratio of 1:1:0.03. The solution was stirred and refluxed while being irradiated with UV light at a wavelength of 360 nm for 10 minutes, resulting in a thiol-olefin click chemistry reaction to obtain an organic ligand containing thiol groups. Then, 1,4-butanedithiol-grafted 2-vinyl terephthalic acid and photoinitiator 1173 were added in a mass ratio of 1:0.6:0.02 to the polymer. The solution was irradiated with UV light at a wavelength of 365 nm for 15 minutes, resulting in a thiol-olefin click chemistry reaction to achieve a terephthalic acid-containing structure in the polymer chain. Finally, an equimolar amount of a mixed salt of ZrCl4 and HfCl4 was added, and after stirring and dissolution, the solution was poured into a polytetrafluoroethylene reactor and heated to 120 °C. The reaction was carried out at ℃ for 12 hours, followed by soaking, centrifugation and washing 5 times. Then, it was redispersed in toluene solution and coated on hollow fiber polyimide-based membrane using the dip-coating method. After drying at 80 ℃ for 8 hours, a polyUiO-66-SH(Zr / Hf) / PEI mixed matrix membrane was obtained.

[0073] Example 4

[0074] In this embodiment, the thiol-containing organic ligand is prepared by chemical reaction of an alkenyl-containing organic ligand and a polythiol compound. The ultraviolet radiation-induced crosslinking of the polyMOF mixed matrix membrane includes the following steps:

[0075] Acrylic anhydride and sodium alginate were dissolved in water at a functional group molar ratio of 4:1 and refluxed at 40 °C for 6 hours to form a 3 wt% acryloyloxy-terminated sodium alginate solution. 2,5-bis(allyloxy)terephthalic acid, mercapto polyethylene glycol mercapto, and photoinitiator 1173 were dissolved in ethanol at 80 °C in a molar ratio of 1:1:0.03. The solution was stirred and refluxed while being irradiated with UV light at a wavelength of 365 nm for 8 minutes to obtain a mercapto-containing organic ligand via a mercapto-olefin click chemistry reaction. Then, mercapto-grafted 2,5-bis(allyloxy)terephthalic acid and photoinitiator 1173 were added at a mass ratio of 1:0.6:0.02 to the polymer. The solution was irradiated with UV light at a wavelength of 360 nm for 30 minutes to achieve a terephthalic acid-containing structure in the polymer chain via a mercapto-olefin click chemistry reaction. Finally, Cr(NO3)3·9H2O, in equimolar amounts to the ligand, was added and dissolved by stirring. The solution was then poured into a polytetrafluoroethylene reactor and heated to 100 °C. The mixture was reacted at ℃ for 12 hours, then soaked, centrifuged and washed 5 times, and then redispersed in toluene solution. It was coated on hollow fiber polyimide-based membrane by dip-coating method and dried at 70℃ for 12 hours to obtain polyMIL-125 / SA mixed matrix membrane.

[0076] Comparative Example 1

[0077] The hybrid matrix film was prepared using a physical doping method, and the specific steps are as follows:

[0078] The solvent n-heptane, polymer hydroxyl-terminated silicone rubber, crosslinking agent tetraethyl orthosilicate, catalyst dibutyltin laurate, and filler UiO-66-SH powder were selected according to a mass ratio of 100:10:1:0.1:4.3. Figure 2 (a) Preparation of a 30 wt% mixed matrix membrane, the surface / cross-section of which is as follows: Figure 3 As shown.

[0079] Comparative Example 2

[0080] The mixed matrix membrane was prepared using a chemical crosslinking method, and the specific steps are as follows:

[0081] A 30 wt% mixed matrix film was prepared using a mass ratio of 100:10:0.5:4.3, consisting of solvent n-heptane, polymer hydroxyl-terminated silicone rubber, crosslinking agent 2,2'-[[2,2-bis[(oxocyclopropylmethoxy)methyl]-1,3-propylidene]bis(oxomethylene)]bis-epoxyethylene, and filler UiO-66-SH powder. The surface / cross-section of the film is shown below. Figure 4 As shown.

[0082] Comparative Example 3

[0083] Pure PDMS membrane was prepared by blending, crosslinking and casting a film using a solvent n-heptane, a polymer hydroxyl-terminated silicone rubber, a crosslinking agent tetraethyl orthosilicate and a catalyst dibutyltin laurate in a mass ratio of 100:10:1:0.1:4.3 to obtain a pure PDMS membrane.

[0084] Performance testing

[0085] (1) The matrix membranes prepared in Examples 1-2 and Comparative Examples 1-3 were used to separate 18wt% MMA / methanol azeotrope by pervaporation at 50 °C. The membrane flux and the concentration of MMA on the permeate side were measured respectively. The specific results are shown in Table 1.

[0086] Table 1. Separation effect of matrix membrane during pervaporation process at 50 °C

[0087]

[0088] The data in Table 1 reveal the decisive influence of the film formation mechanism on molecular sieving efficiency. First, the pure PDMS membrane in Comparative Example 3 exhibits the highest permeation flux but low selectivity. The physically doped Comparative Example 1 shows a relatively high membrane flux, but its permeate-side MMA concentration is only 32.5%, indicating that the separation efficiency still needs improvement. This high flux and low selectivity phenomenon is a typical manifestation of the lack of interfacial sieving effect. Because there is only physical contact between the UiO-66-SH particles and the PDMS matrix, non-selective micron-sized voids are formed at the interface, allowing both small-molecule methanol and large-molecule MMA to pass through without hindrance. In contrast, although the flux of Example 1 decreased to 0.68 kg / m³, the overall efficiency improved significantly. 2 However, the MMA concentration on the permeation side surged to 59.5 wt%. This selective enhancement confirms that UV irradiation-induced in-situ growth successfully constructed a dense, defect-free interface.

[0089] (2) The matrix membranes prepared in Examples 1-2 and Comparative Examples 1-3 were used to separate 1 wt% phenol / water at 70 °C. The membrane flux and the concentration of phenol on the permeate side were measured respectively. The specific results are shown in Table 2 and 3. Figure 5 .

[0090] Table 2. Performance of the matrix membrane in separating 1 wt% phenol / water at 70 °C.

[0091]

[0092] The data in Table 2 show that under high temperature conditions, the thermal motion of the polymer chains intensifies. Compared with Comparative Example 3, the interfacial defects of the physically doped film in Comparative Example 1 are further amplified, leading to a large amount of water molecules permeating through it. While the phenol concentration on the permeate side is only 10.2%, the flux is as high as 5.51 kg / m³. 2This is actually a typical characteristic of interfacial debonding that can occur in membrane structures at high temperatures. Examples 1 and 2 achieved extremely high phenol concentrations of 33.7 wt% and 29.2 wt%, respectively, while maintaining moderate flux. This result demonstrates that the covalent bonds introduced through mercapto-olefin click chemistry not only act as nucleation sites but also serve as "molecular rivets" at high temperatures. This strong chemical bonding inhibits the thermal slippage of polymer chains on the MOF surface and the solvent-induced plasticization effect, maintaining a rigid sieve-like pore structure. Furthermore, although the chemical crosslinking method in Comparative Example 2 introduced a crosslinking agent, it only achieved a separation purity of 24.1 wt%, indicating that simple polymer matrix crosslinking cannot solve the problem of poor interfacial compatibility between MOF particles and the matrix.

[0093] (3) The matrix membrane prepared in Examples 3-4 was used to separate 20 wt% methanol / methyl acetate azeotrope and 1 wt% water / butanol at 70 ℃ through pervaporation process. The membrane flux and the concentration of phenol on the permeate side were measured respectively. The specific results are shown in Table 3.

[0094] Table 3 Separation performance of the matrix membrane

[0095]

[0096] In Example 3, the PEI matrix formed covalent connections with the cluster nodes on polyUiO-66-SH (Zr / Hf), restricting the free movement of the polymer chains and reducing the free volume. This resulted in a significant retention effect on the large methyl acetate molecule. Simultaneously, the hydrogen bonds in the membrane and the rigid channels of the MOF provided preferential pathways for methanol molecules. Furthermore, the excellent performance of the sodium alginate matrix in the high-temperature aqueous system of Example 4 broke the traditional constraint that hydrophilic polymers easily swell excessively in water and lose selectivity. This indicates that the in-situ grown polyMIL-125 network effectively crosslinked the sodium alginate backbone, constructing a swelling-resistant rigid framework.

[0097] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A UV irradiation-induced polyMOF hybrid matrix membrane, characterized in that, The invention comprises a polymer matrix and in-situ grown MOF crystals. The polymer matrix has MOF organic ligands covalently grafted onto its molecular chains via a mercapto-alkene click chemistry reaction. The MOF crystals are in-situ grown and embedded in the polymer matrix using the MOF organic ligands as nucleation sites.

2. The method for preparing the ultraviolet irradiation-induced polyMOF hybrid matrix film according to claim 1, characterized in that, Includes the following steps: S1. Preparation of acrylate-containing polymers: A monomer with acrylate groups is grafted onto a polymer with active functional groups in a solvent to obtain a modified polymer solution containing acrylate groups. S2. Introduction of photoinduced ligands: Add thiol-containing organic ligands and photoinitiators to the modified polymer solution, and carry out thiol-alkene click chemistry reaction under ultraviolet light irradiation to obtain cross-linked polymer precursors containing organic ligand structures; S3. In-situ synthesis of polyMOF: Metal salts are added to the cross-linked polymer precursor and a solvothermal reaction is carried out to induce the coordination of metal ions with organic ligands on the polymer chain. A mixture containing polyMOF particles and further cross-linked polymer network is synthesized in situ. After washing and centrifugation, polyMOF mixed matrix material is obtained. S4. Film formation and curing: The polyMOF mixed matrix material is dispersed in a solvent to prepare a coating solution, which is then coated on the surface of the base film and dried to obtain the polyMOF mixed matrix film.

3. The preparation method according to claim 2, characterized in that, In step S1, the active functional group is one or more of hydroxyl, carboxyl, or amino groups; The polymer is one or more of the following: hydroxyl-terminated siloxane, amino-terminated siloxane, side-chain aminosiloxane, polyethyleneimine, sodium alginate, polyvinyl alcohol, chitosan, and polyether block amide. The monomers containing acrylate groups are one or more of acryloyl chloride, acrylic acid, glycidyl acrylate, 4-hydroxybutyl acrylate glycidyl ether, and acrylic anhydride; The molar ratio of monomers with acrylate groups to polymers is 1:1-10:1, the reaction temperature is 30-100 ℃, and the reaction time is 3-48 h.

4. The preparation method according to claim 2, characterized in that, In step S2, the thiol-containing organic ligand is either an organic ligand that contains a thiol group itself or is prepared by a thiol-alkene click chemical reaction between an alkene-containing organic ligand and a multi-thiol small molecule compound.

5. The preparation method according to claim 4, characterized in that, The organic ligand containing a thiol group is one or more of 2-mercaptoterephthalic acid, 2,5-dimercaptoterephthalic acid, 2,3-dimercaptoterephthalic acid, or vinylterephthalic acid modified with polythiol small molecules, 2-(allyloxy)terephthalic acid, 2,5-bis(allyloxy)terephthalic acid, and 2,5-bis(4-carboxyphenyl)-1,4-bis(allyloxy)benzene.

6. The preparation method according to claim 4, characterized in that, The aforementioned The small molecules containing multiple thiol groups are one or more of the following: 1,4-butanedithiol, 1,6-hexanedithiol, 2,7-dimercaptonaphthalene, 1,4-benzenedimethylthiol, 2,3-dimercaptosuccinic acid, thiol polyethylene glycol thiol, and pentaerythritol tetramercaptoacetate. The olefin-containing organic ligand is one or more of 2-vinyl terephthalic acid, 2-(allyloxy) terephthalic acid, 2,5-bis(allyloxy) terephthalic acid, and 2,5-bis(4-carboxyphenyl)-1,4-bis(allyloxy)benzene.

7. The preparation method according to claim 2, characterized in that, In step S2, the molar ratio of the acrylate-containing modified polymer, the mercapto-containing organic ligand, and the photoinitiator is 1:0.5:0.01-4:1:0.5; The wavelength of ultraviolet irradiation is 300-400 nm, and the irradiation time is 0.1-6 h.

8. The preparation method according to claim 2, characterized in that, In step S3, the molar ratio of the crosslinked polymer precursor to the metal ions in the metal salt is 1:0.5-2. The metal salt is one or more of the following: zirconium salt, iron salt, aluminum salt, chromium salt, titanium salt, hafnium salt, and zinc salt; The temperature of the solvothermal reaction is 50-200 ℃, and the reaction time is 6-36 h; The in-situ synthesized polyMOF particles are one of polyUiO-66, polyMIL-101, polyMIL-53, polyMIL-88B(Fe), polyMOF-5, polyMIL-125, or polyUiO-68.

9. The preparation method according to claim 2, characterized in that, In step S4, the solvent of the coating solution is one or more of toluene, benzene, n-heptane, ethyl acetate, dichloromethane, water, ethanol, and butanol. The concentration of the polyMOF mixed matrix material in the coating solution is 1 wt%-70 wt%; The base membrane has one of the following configurations: flat sheet, hollow fiber, tubular, ceramic sheet, or corrugated structure; and its material is one of the following: alumina, yttrium oxide, titanium oxide, silicon carbide, polyacrylonitrile, polycarbonate, polyvinylidene fluoride, polytetrafluoroethylene, polyethersulfone, polysulfone, or polyimide. The drying temperature is 20-100 ℃, and the time is 0.5-12 h.

10. The application of the ultraviolet irradiation-induced polyMOF hybrid matrix membrane according to claim 1 in liquid separation, gas separation or ion separation processes.

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