Photocrosslinkable perfluorinated ion membranes and methods for making the same

Abstract

The present application relates to a photo-crosslinkable perfluorinated ion membrane and a method for preparing the same, wherein the photo-crosslinkable perfluorinated ion membrane is obtained by mixing a perfluorinated ion exchange resin containing sulfonic acid groups or phosphoric acid groups as a film-forming resin with a quaternized photosensitive compound.

Description

Technical Field

[0001] This invention relates to the field of fluorine-containing polymer materials technology, and specifically to a photocrosslinkable perfluorinated ion exchange membrane and its preparation method. Background Technology

[0002] Proton exchange membranes (PEMs) are ionomers that, due to their exceptionally high proton conductivity, have been widely used in industrial applications such as fuel cells, ion exchangers, water purification, electrodialysis, chlor-alkali production, and seawater desalination. They are also increasingly being used as a potential component in artificial synaptic devices. However, uncrosslinked perfluorinated ion exchange membranes suffer from low mechanical strength, poor solvent resistance, and poor dimensional stability, which are significant problems limiting their use. Therefore, finding an efficient and easily controllable method for preparing crosslinkable perfluorinated ion exchange membranes is crucial for improving their performance.

[0003] CN106432765A discloses a perfluorinated ion exchange membrane with uniformly distributed crosslinking points, its preparation method, and its applications. This perfluorinated ion exchange membrane is obtained by first preparing a perfluorosulfonamide resin, then melt-blending it with a perfluorosulfonyl halide resin, followed by catalysis to achieve a membrane with uniformly distributed crosslinking points. However, the synthesis of the resin used for crosslinking in this method is complex, and the membrane fabrication process is cumbersome. Currently reported methods for improving the mechanical stability of perfluorinated ion exchange membranes mainly involve crosslinking the membrane or adding reinforcing materials. Crosslinking is mainly divided into two types based on different mechanisms: physical crosslinking and chemical crosslinking. Physical crosslinking primarily involves adding polyvalent metal ions, where acidic groups in the polymer matrix form ionic bonds with these metal ions, thereby improving the membrane's mechanical properties. Chemical crosslinking involves introducing active groups such as sulfonamides to crosslink with acidic groups in the proton exchange membrane, forming covalent bonds, thus improving the membrane's mechanical stability. Adding reinforcing materials to perfluorinated ion exchange membranes, such as adding polytetrafluoroethylene fibers to perfluorosulfonic acid resin, can enhance the membrane's strength; however, the filler and polymer are not chemically bonded together, resulting in poor stability.

[0004] Therefore, there is a market demand for perfluorinated ion exchange membranes with further improved stability and their preparation methods. Summary of the Invention

[0005] One object of the present invention is to provide a photocrosslinkable perfluorinated ion exchange membrane that provides excellent stability, addressing the shortcomings of current perfluorinated ion exchange membranes.

[0006] One aspect of the present invention provides a photocrosslinkable perfluorinated ion exchange membrane, characterized in that it is obtained by mixing a perfluorinated ion exchange resin containing sulfonic acid groups or phosphate groups as the film-forming resin with a quaternized photosensitive compound.

[0007] Another aspect of the present invention provides a method for preparing a photocrosslinkable perfluorinated ion exchange membrane according to the present invention, comprising the following steps:

[0008] (1): A compound containing a tertiary amine group is mixed with a photosensitive compound in an organic solvent to obtain a mixed solution;

[0009] (2): The mixed solution is heated and stirred under an inert gas atmosphere, and the compound containing the tertiary amine group undergoes a quaternization reaction with the photosensitive compound;

[0010] (3): The product was precipitated from the resulting reaction mixture using a poor solvent, and then obtained by filtration and drying to obtain the quaternized photosensitive compound;

[0011] (4): Dissolve the quaternized photosensitive compound and the perfluorinated ion exchange resin in a mixed solvent, mix them evenly, and then evaporate the solvent to obtain a photocrosslinkable perfluorinated ion membrane.

[0012] By combining physical crosslinking and chemical crosslinking, this invention provides a novel photocrosslinkable perfluorinated ion exchange membrane. The advantages of this novel photocrosslinkable perfluorinated ion exchange membrane are: (1) Simple preparation, no need for complicated chemical synthesis. By mixing the perfluorinated ion exchange resin with the photocrosslinkable small molecules in a solvent and evaporating the solvent by casting, a film with uniform texture can be obtained; (2) High dispersion stability and strong universality. Based on physical crosslinking, the photocrosslinkable small molecules can form ionic bonds with the acidic groups between the perfluorinated ion exchange resin through supramolecular interactions, which helps the molecules to disperse inside the ion exchange membrane; (3) High degree of freedom in selecting the crosslinking region. Based on the photocrosslinkable functional groups, the crosslinking region can be freely controlled by controlling the ultraviolet light exposure area.

[0013] Furthermore, the photocrosslinkable perfluorinated ion exchange membrane according to the present invention also has the following additional benefits. Based on photochemical reactions, the photochemical crosslinking of functional groups in the photocrosslinkable small molecules leads to chemical crosslinking within the material, further enhancing the mechanical strength of the material; the photocrosslinkable perfluorinated ion exchange membrane provided by the present invention combines the advantages of physical and chemical crosslinking, and the chemically crosslinked structure can be obtained through simple ultraviolet irradiation; the photocrosslinkable small molecules in the present invention can be synthesized by a simple one-step method and can be uniformly dispersed within the perfluorinated ion exchange membrane.

[0014] Details of one or more embodiments of the present invention are set forth in the following description. Other features, objects, and advantages of the invention will become clear from the description and claims.

[0015] definition

[0016] In this document, the terms “a”, “the”, “at least one”, and “one or more” are used interchangeably. Thus, for example, a coating composition containing “a” additive can be interpreted as meaning that the coating composition contains “one or more” additives.

[0017] When a composition is described as including or comprising a specific component or fraction, it is anticipated that optional components or fractions not covered by the present invention are not excluded from the composition, and that the composition may be constituted or composed of the involved components or fractions. Similarly, when a method is described as including or comprising a specific process step, it is anticipated that optional process steps not covered by the present invention are not excluded from the method, and that the method may be constituted or composed of the involved process steps.

[0018] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, just as any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an undefined range.

[0019] The term "quaternization reaction" as used in this article refers to the reaction of a tertiary amine R3N with a haloalkane RX to produce a quaternary ammonium salt [R4N]. + ][X - [The reaction.]

[0020] The term "poor solvent" as used in this article refers to a solvent that has a weak ability to dissolve a solute and whose interaction parameter χ with the solute is close to or greater than 0.5.

[0021] The terms "preferred" and "ideally" refer to embodiments of the invention that provide certain benefits in certain circumstances. However, other embodiments may also be preferred in the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of the invention.

[0022] When the term "comprising" and its variations appear in the specification and claims, these terms are not intended to be limiting.

[0023] In this document, a statement of a numerical range by endpoints includes all numbers contained within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). Furthermore, the disclosure of a range includes the disclosure of all subranges included within a wider range (e.g., 1 to 5 discloses 1 to 4, 1.5 to 4.5, 1 to 2, etc.). Attached Figure Description

[0024] Figure 1 The proton NMR spectrum of a photocrosslinkable quaternary ammonium photosensitive compound according to one embodiment of the present invention.

[0025] Figure 2 This is a physical image of a perfluorinated ion exchange membrane according to one embodiment of the present invention.

[0026] Figure 3 The image shows the fluorescence of a perfluorinated ion exchange membrane under a 365nm UV lamp before and after selective photocrosslinking according to an embodiment of the present invention.

[0027] Figure 4 The graph shows the change in mechanical properties of a perfluorinated ion exchange membrane according to one embodiment of the present invention before and after irradiation with 365nm ultraviolet light. Detailed Implementation

[0028] One aspect of the present invention provides a photocrosslinkable perfluorinated ion exchange membrane, characterized in that it is obtained by mixing a perfluorinated ion exchange resin containing sulfonic acid groups or phosphate groups as the film-forming resin with a quaternized photosensitive compound.

[0029] In an embodiment of the present invention, the structure of the perfluorinated ion exchange resin containing sulfonic acid groups is as follows:

[0030]

[0031] Where m≥1, n≥1.

[0032] The structure of a perfluorinated ion exchange resin containing phosphate groups is as follows:

[0033]

[0034] The constraints for m and n are as described above, i.e., m≥1, n≥1.

[0035] Perfluorinated ion exchange resins can contain both sulfonic acid groups and phosphate groups, or only one type of group. When both types of groups are present, the ratio of sulfonic acid groups to phosphate groups is 90:10 to 10:90. During production, the resin is dissolved in a solvent and concentrated to a suitable concentration. The concentration of the solution varies depending on the solvent used and can range from 1% to 30%.

[0036] In an embodiment of the present invention, the quaternized photosensitive compound is obtained by a quaternization reaction of a compound containing a tertiary amine group with a photosensitive compound. In an embodiment of the present invention, the compound containing a tertiary amine group has the structural formula shown in formula (1):

[0037]

[0038] Wherein, X1 and X2 are independently selected from tertiary amine, imidazole, and pyridine groups, respectively; a and b are integers and are independently selected from 0 or 1, but cannot both be 0; and R1 is C1-C2. 20 Straight-chain or branched alkyl groups.

[0039] As a preferred example, the compound containing a tertiary amine group is selected from trimethylamine, triethylamine, tributylamine, N,N-dimethylethylamine, N,N-dimethylhexylamine, N,N-dimethyln-octylamine, N,N-dimethyldecylamine, N,N-dimethyldodecylamine, N,N-dimethyltetradecylamine, N,N,N,N-tetramethyl-1,6-hexanediamine, dodecylbenzylmethylamine, N-methyldicyclohexylamine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2-propylpyridine, 3-propylpyridine, 4-propylpyridine, 2-butylpyridine, 3-butylpyridine, 4-butylpyridine, 2-pentylpyridine, 3-pentylpyridine, 4-pentylpyridine, 1,2 - bis(4-pyridyl)ethane, 4-(2-dimethylaminoethyl)pyridine, 1-methylimidazole, 2-methylimidazole, 3-methylimidazole, 4-methylimidazole, 1-ethylimidazole, 2-ethylimidazole, 3-ethylimidazole, 4-ethylimidazole, 1-propylimidazole, 2-propylimidazole, 3-propylimidazole, 4-propylimidazole, preferably selected from trimethylamine, N,N-dimethylethylamine, N,N-dimethylhexylamine, N,N-dimethyln-octylamine, N,N-dimethyldecylamine, N,N-dimethyldodecylamine, N,N-dimethyltetradecylamine, N,N,N,N-tetramethyl-1,6-hexanediamine, 4-n-propylpyridine, 1,2-bis(4-pyridyl)ethane, 4-(2-dimethylaminoethyl)pyridine, 1-propylimidazole.

[0040] In an embodiment of the present invention, the photosensitive compound is selected from one or more of the following formulas:

[0041]

[0042] Wherein X3, X4, and X5 are halogens, such as fluorine, chlorine, bromine, and iodine, preferably chlorine and bromine, more preferably chlorine; R2 and R7 are C1-C 20 Straight-chain or branched alkyl groups; R3, R4, R5, and R6 are each independently selected from hydrogen, C1-C6, C2-C4, C3-C4, C5-C6, C6 ... 20 Straight-chain or branched alkyl groups, C1-C20 Alkoxy, nitro, hydroxy, nitrile, ester, cycloalkyl, phenyl, or naphthyl; n1, n2, n3, and n4 are integers between 0 and 4.

[0043] When exposed to visible and / or UV light, photon absorption by a photosensitive compound can lead to electronic excitation. After excitation, an electron from one electron pair may rise from a lower-energy ground state to a higher-energy excited state. This electron pair may be unpaired, with one electron in the excited state and the other in the ground state. In one aspect, the excited electron may not change its spin orientation and may retain a spin orientation opposite to that of the other unpaired electron. Such an excited molecule is in a singlet excited state. In another aspect, the excited electron changes its spin orientation, becoming parallel to the spin orientation of the other unpaired electron. Such an excited molecule is in a triplet excited state.

[0044] Because the photosensitive compound needs to undergo a quaternization reaction with a compound containing a tertiary amine group, that is, the tertiary amine R3N reacts with a haloalkane RX to generate a quaternary ammonium salt [R4N]. + ][X - The reaction. Therefore, in embodiments of the present invention, the photosensitive compound is selected from halogenated anthracene compounds, coumarins, and cinnamic acid compounds.

[0045] Halogenated anthracene compounds include, but are not limited to, one or more of 9-chloromethylanthracene, 9,10-dichloromethylanthracene, 9-bromomethylanthracene, 9,10-dibromomethylanthracene, and 2-chloroethylanthracene.

[0046] Halogenated coumarin compounds include, but are not limited to, 3-chlorocoumarin, 6-bromocoumarin, 6-chloro-4-hydroxycoumarin, 3-(bromoacetyl)coumarin, 6-bromocoumarin-3-carboxylic acid, 6-chloro-4-hydroxycoumarin, 3-(bromoacetyl)coumarin, 6-bromo-4-hydroxycoumarin, or coumarin 2, coumarin 6, 4-hydroxycoumarin, 6-hydroxycoumarin, 3-aminocoumarin, coumarin 343, 3-hydroxycoumarin, 6-hydroxycoumarin. One or more of the halogenated products of 3-aminocoumarin, coumarin-3-carboxylic acid, 7-hydroxycoumarin, 6,7-dihydroxycoumarin, 5,7-dihydroxycoumarin, 4,6-dihydroxycoumarin, 6-hydroxy-4-methylcoumarin, 7-hydroxy-4-methylcoumarin, 4-hydroxy-6-methylcoumarin, 7-hydroxycoumarin-4-acetic acid, 4-hydroxy-3-nitrocoumarin, 4-hydroxy-3-nitrocoumarin, 4-hydroxy-6-methylcoumarin, etc.

[0047] Halogenated cinnamic acid compounds include, but are not limited to, one or more of methyl 4-chlorocinnamate, ethyl 4-chlorocinnamate, methyl 4-bromocinnamate, ethyl 4-bromocinnamate, and butyl 4-chlorocinnamate.

[0048] Preferably, the photosensitive compound used in this invention is selected from one or more of 9-chloromethylanthracene, 6-chloro-4-hydroxycoumarin, and methyl 4-chlorocinnamate.

[0049] The advantages of the perfluorinated ion exchange membrane according to the present invention are: (1) It is simple to prepare and does not require complicated chemical synthesis. By mixing the perfluorinated ion exchange resin with photocrosslinkable small molecules in a solvent and evaporating the solvent by casting, a film with uniform texture can be obtained; (2) It has high dispersion stability and strong universality. Based on physical crosslinking, the photocrosslinkable small molecules can form ionic bonds with the acidic groups between the perfluorinated ion exchange resin, which helps the molecules to disperse inside the ion exchange membrane; based on photochemical reaction, the photochemical crosslinking of the functional groups in the photocrosslinkable small molecules causes chemical crosslinking to occur inside the material, which further improves the mechanical strength of the material; (3) It has a high degree of freedom in selecting the crosslinking region. Based on the photocrosslinkable functional groups, the crosslinking region can be freely controlled by controlling the ultraviolet light exposure area.

[0050] Therefore, the present invention also relates to a method for preparing a photocrosslinkable perfluorinated ion exchange membrane according to the present invention, comprising the following steps:

[0051] (1): A compound containing a tertiary amine group is mixed with a photosensitive compound in an organic solvent to obtain a mixed solution;

[0052] (2): The mixed solution is heated and stirred under an inert gas atmosphere, and the compound containing the tertiary amine group undergoes a quaternization reaction with the photosensitive compound;

[0053] (3): The product was precipitated from the resulting reaction mixture using a poor solvent, and then obtained by filtration and drying to obtain a quaternized photosensitive small molecule compound;

[0054] (4): The quaternized photosensitive small molecule compound and the perfluorinated ion exchange resin are dissolved in a mixed solvent, mixed evenly, and the solvent is evaporated to obtain a photocrosslinkable perfluorinated ion membrane.

[0055] The advantages of this preparation method are: (1) The preparation process is simple, and the raw materials do not need to be pretreated in one step; (2) The proportion of photosensitive small molecules in the perfluorinated ion membrane can be flexibly adjusted according to the product requirements to obtain perfluorinated ion membranes with different performance; (3) The raw materials have all been industrialized.

[0056] In an embodiment of the present invention, in step (1), the molar ratio between the photosensitive compound and the compound containing the tertiary amine group is 1:1 to 6:1, preferably 1:1 to 3:1, and more preferably 1:1 to 2:1.

[0057] In embodiments of the present invention, the organic solvent used in step (1) is selected from one or more of ketones, 1,4-dioxane, dimethyl sulfoxide, N,N-dimethylformamide, or N,N-dimethylacetamide. Those skilled in the art can appropriately select the organic solvent used in step (1) based on the choice between the photosensitive compound and the compound containing a tertiary amine group.

[0058] In an embodiment of the present invention, the inert gas in step (2) is nitrogen or argon.

[0059] In an embodiment of the present invention, the reaction time in step (2) is 8-48h, preferably 8-20h; the reaction temperature is 50-130℃, preferably 50-100℃.

[0060] In an embodiment of the present invention, the unsuitable solvent in step (3) is selected from one or more of alcohols, ethers, water, and lipids. The term "unsuitable solvent" refers to a solvent that has a weak solubility for the solute and whose interaction parameter χ with the solute is close to or greater than 0.5. Those skilled in the art can appropriately select the unsuitable solvent used in step (3) based on the selection of the photosensitive compound and the compound containing a tertiary amine group.

[0061] In an embodiment of the present invention, the perfluorinated ion exchange resin is a perfluorinated ion exchange resin containing carboxylic acid groups (perfluorosulfonic acid resin), a perfluorinated ion exchange resin containing phosphate groups (perfluorophosphate resin), or a combination thereof. The structure of the perfluorinated ion exchange resin containing carboxylic acid groups is as follows:

[0062]

[0063] Where m≥1, n≥1.

[0064] The structure of a perfluorinated ion exchange resin containing phosphate groups is as follows:

[0065]

[0066] The constraints for m and n are as described above, i.e., m≥1, n≥1.

[0067] Perfluorinated ion exchange resins can contain both sulfonic acid groups and phosphate groups, or only one type of group. When both types of groups are present, the ratio of sulfonic acid groups to phosphate groups is 90:10 to 10:90. During production, the resin is dissolved in a solvent and concentrated to a suitable concentration. The concentration of the solution varies depending on the solvent used and can range from 1% to 30%.

[0068] In an embodiment of the present invention, the mixed solvent in step (4) is two or more of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, ethylenediamine, propylenediamine, butanediamine, pentanediamine, isopropylamine, water, and ethanol.

[0069] In an embodiment of the present invention, the solvent evaporation temperature in step (4) is 10-200°C, preferably 50-150°C; the evaporation time is 0.5h-48h, preferably 5-40h.

[0070] In an embodiment of the present invention, in step (4), the quaternized photosensitive small molecule and the perfluorinated ion exchange resin are dissolved in a mixed solvent in the desired proportion, mixed evenly, and then poured onto a horizontal plate. The plate can be selected from a glass plate, a Hastelloy steel plate, or a polytetrafluoroethylene plate. A technician can select the appropriate plate as needed.

[0071] In addition, the method may optionally include step (5), namely, irradiating the perfluorinated ion membrane with ultraviolet light to obtain perfluorinated ion membranes with different mechanical properties, or obtaining locally cross-linked perfluorinated ion membranes by selective irradiation through a mask.

[0072] This invention combines physical crosslinking and chemical crosslinking to provide a novel photocrosslinkable perfluorinated ion exchange membrane. The advantages of this novel photocrosslinkable perfluorinated ion exchange membrane are: (1) Simple preparation, no need for complicated chemical synthesis. By mixing the perfluorinated ion exchange resin with the photocrosslinkable small molecules in a solvent and evaporating the solvent using a casting method, a film with uniform texture can be obtained; (2) High dispersion stability and strong universality. Based on physical crosslinking, the photocrosslinkable small molecules can form ionic bonds with the acidic groups between the perfluorinated ion exchange resin through supramolecular interactions, thus helping the molecules to disperse inside the ion exchange membrane; based on photochemical reaction, the photochemical crosslinking of the functional groups in the photocrosslinkable small molecules causes chemical crosslinking inside the material, further improving the mechanical strength of the material; (3) High degree of freedom in selecting the crosslinking region. Based on the photocrosslinkable functional groups, the crosslinking region can be freely controlled by controlling the ultraviolet light exposure area. The advantages of the preparation method according to the present invention are: (1) the preparation process is simple, the one-step synthesis is adopted, and no pretreatment is required for the raw materials; (2) the proportion of photosensitive small molecules in the perfluorinated ion membrane can be flexibly adjusted according to the product needs to obtain perfluorinated ion membranes with different performance; (3) the raw materials have all been industrialized.

[0073] Example

[0074] The following examples describe the disclosure of this invention in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight, and all reagents used in the examples are commercially available and ready for use without further processing.

[0075] Test methods

[0076] Unless otherwise indicated, the following test methods are used in the following embodiments.

[0077] 1H NMR spectrum

[0078] This test was used to determine the structure of the target product. The measurements were performed at room temperature using an AVANCE III HD 500MHz nuclear magnetic resonance spectrometer from Bruker (Germany), with deuterated dimethyl sulfoxide (DMSO) as the solvent and tetramethylsilane (TMS) as the internal standard.

[0079] Mechanical properties

[0080] This test was used to characterize the mechanical properties of the obtained perfluorinated ion exchange membrane. The photocrosslinkable perfluorinated ion exchange membrane of this invention was UV cured using an LED point light source from Uvata Corporation (China), with a wavelength of 365 nm and a light intensity of 15 mW / cm². 2 Then, according to standard ISO 527-2, stress and strain tests were performed on the cross-linked or partially cross-linked perfluorinated ion exchange membranes using an Instron 3365 electronic universal testing machine from Instron Corporation, USA.

[0081] Example 1:

[0082] A photocrosslinkable perfluorinated ion exchange membrane is prepared by means of the following steps:

[0083] (1) Preparation of quaternized photosensitive small molecule compound: 3.27 g of N,N-dimethyl-n-octylamine and 4.54 g of 9-chloromethylanthracene were mixed in 50 mL of acetone. Under nitrogen protection, the mixture was heated to 56 °C and refluxed for 10 h. After the reaction was completed, the mixture was cooled to room temperature and precipitated with anhydrous diethyl ether. The solid obtained was filtered and dried to obtain a yellow powdery solid product, namely the quaternized photosensitive small molecule compound-1, with a yield of approximately 90%. Figure 1 This is the hydrogen NMR spectrum of the target product.

[0084] (2) Preparation of photocrosslinkable perfluorinated ion exchange membrane: Take 1g of the formula

[0085]

[0086] A perfluorosulfonic acid resin with Mn=1000 was dissolved in a mixed solution of DMF (5 ml) and isopropylamine (5 ml) at room temperature. After mixing evenly, 0.05 g of photosensitizing compound-1 was added, and the mixture was heated and stirred at 80 °C to dissolve. Then, 2 ml of deionized water was added, and the evenly mixed casting solution was poured onto a horizontally placed glass plate. The perfluoro ion exchange membrane that can be photocrosslinked was obtained by evaporation at 80 °C for 24 h. Figure 2 This is a photograph of the obtained perfluorinated ion exchange membrane.

[0087] (3) The perfluorinated ion exchange membrane obtained in (2) can be photocrosslinked under 365nm ultraviolet light, or local photocrosslinking can be achieved through a mask.

[0088] Figure 3 These are fluorescence images of the perfluorinated ion exchange membrane under a 365nm UV lamp before and after selective photocrosslinking.

[0089] Figure 4 This is a graph showing the changes in the mechanical properties of a perfluorinated ion exchange membrane before and after ultraviolet light irradiation.

[0090] Example 2:

[0091] A photocrosslinkable perfluorinated ion exchange membrane is prepared by means of the following steps:

[0092] (1) Preparation of quaternized photosensitive small molecule compound: 3.27 g of N,N-dimethyl-n-octylamine and 3.93 g of 6-chloro-4-hydroxy-2H-pyran-2-one were mixed in 50 mL of acetone. Under nitrogen protection, the mixture was heated to 56 °C and refluxed for 10 h. After the reaction was completed, the mixture was cooled to room temperature and precipitated with anhydrous diethyl ether. The solid obtained was filtered and dried to obtain a powdered solid product, namely the quaternized photosensitive small molecule compound-2, with a yield of approximately 50%.

[0093] (2) Preparation of photocrosslinkable perfluorinated ion exchange membrane: Take 1g of the formula

[0094]

[0095] A perfluorophosphate resin with Mn=900 was dissolved in a mixed solution of DMF (5 ml) and isopropylamine (5 ml) at room temperature. After mixing evenly, 0.1 g of photosensitizing compound-2 was added, and the mixture was heated and stirred at 80 °C to dissolve. Then, 2 ml of deionized water was added, and the evenly mixed casting solution was poured onto a horizontally placed glass plate. The perfluorophosphate membrane that can be photocrosslinked was obtained by evaporation at 80 °C for 24 h.

[0096] (3) The perfluorinated ion exchange membrane obtained in (2) can be photocrosslinked under 365nm ultraviolet light, or local photocrosslinking can be achieved through a mask.

[0097] Example 3:

[0098] A photocrosslinkable perfluorinated ion exchange membrane is prepared by means of the following steps:

[0099] (1) Preparation of quaternized photosensitive small molecule compound: 3.27 g of N,N-dimethyl-n-octylamine and 3.93 g of methyl 4-chlorocinnamate were mixed in 50 mL of acetone. Under nitrogen protection, the mixture was heated to 56 °C and refluxed for 10 h. After the reaction was completed, the mixture was cooled to room temperature and precipitated with anhydrous diethyl ether. The solid obtained was filtered and dried to obtain a powdered solid product, namely the quaternized photosensitive small molecule compound-3, with a yield of approximately 70%.

[0100] (2) Preparation of photocrosslinkable perfluorinated ion exchange membrane: Take 1g of the formula

[0101]

[0102] A perfluorosulfonic acid resin with Mn=1200 was dissolved in a mixed solution of DMF (5 ml) and isopropylamine (5 ml) at room temperature. After mixing evenly, 0.1 g of photosensitizing compound-3 was added, and the mixture was heated and stirred at 80 °C to dissolve. Then, 2 ml of deionized water was added, and the evenly mixed casting solution was poured onto a horizontally placed glass plate. The perfluoro ion exchange membrane that can be photocrosslinked was obtained by evaporation at 80 °C for 24 h.

[0103] (3) The perfluorinated ion exchange membrane obtained in (2) can be photocrosslinked under 365nm ultraviolet light, or local photocrosslinking can be achieved through a mask.

[0104] Example 4:

[0105] A photocrosslinkable perfluorinated ion exchange membrane is prepared by means of the following steps:

[0106] (1) Preparation of quaternized photosensitive small molecule compound: 3.45 g of N,N,N,N-tetramethyl-1,6-hexanediamine and 9.07 g of 9-chloromethylanthracene were mixed in 50 mL of DMF solution. Under nitrogen protection, the mixture was heated to 80 °C and reacted for 10 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, and washed with DMF. The resulting solid was dried to obtain a pale yellow powdery solid product, namely the quaternized photosensitive small molecule compound-4, with a yield of approximately 90%.

[0107] (2) Preparation of photocrosslinkable perfluorinated ion exchange membrane: Take 1g of the formula

[0108]

[0109] A perfluorophosphate resin with Mn=1000 was dissolved in a mixed solution of DMSO (5 ml) and isopropylamine (5 ml) at room temperature. After mixing evenly, 0.1 g of photosensitizing compound-4 was added, and the mixture was heated and stirred at 80 °C to dissolve. Then, 2 ml of deionized water was added, and the evenly mixed casting solution was poured onto a horizontally placed glass plate. The perfluorophosphate membrane that can be photocrosslinked was obtained by evaporation at 80 °C for 24 h.

[0110] (3) The perfluorinated ion exchange membrane obtained in (2) can be photocrosslinked under 365nm ultraviolet light, or local photocrosslinking can be achieved through a mask.

[0111] Example 5:

[0112] A photocrosslinkable perfluorinated ion exchange membrane is prepared by means of the following steps:

[0113] (1) Preparation of quaternized photosensitive small molecule compound: 2.24 g of 4-n-propylpyridine and 4.54 g of 9-chloromethylanthracene were mixed in 50 mL of acetone. Under nitrogen protection, the mixture was heated to 56 °C and refluxed for 10 h. After the reaction was completed, the mixture was cooled to room temperature and precipitated with anhydrous diethyl ether. The solid obtained was filtered and dried to obtain a pale yellow powdery solid product, namely the quaternized photosensitive small molecule compound-5, with a yield of approximately 80%.

[0114] (2) Preparation of photocrosslinkable perfluorinated ion exchange membrane: Take 1g of the formula

[0115]

[0116] A perfluorosulfonic acid resin with Mn=1100 was dissolved in a mixed solution of DMF (5 ml) and isopropylamine (5 ml) at room temperature. After mixing evenly, 0.1 g of photosensitizing compound-5 was added, and the mixture was heated and stirred at 80 °C to dissolve. Then, 2 ml of deionized water was added, and the evenly mixed casting solution was poured onto a horizontally placed glass plate. The perfluoro ion exchange membrane that can be photocrosslinked was obtained by evaporation at 80 °C for 24 h.

[0117] (3) The perfluorinated ion exchange membrane obtained in (2) can be photocrosslinked under 365nm ultraviolet light, or local photocrosslinking can be achieved through a mask.

[0118] Example 6:

[0119] A photocrosslinkable perfluorinated ion exchange membrane is prepared by means of the following steps:

[0120] (1) Preparation of quaternized photosensitive small molecule compound: 3.68 g of 1,2-bis(4-pyridyl)ethane and 9.07 g of 9-chloromethylanthracene were mixed in 50 mL of DMF solution. Under nitrogen protection, the mixture was heated to 80 °C and reacted for 10 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, and washed with DMF. The resulting solid was dried to obtain a pale yellow powdery solid product, namely the quaternized photosensitive small molecule compound-6, with a yield of approximately 70%.

[0121] (2) Preparation of photocrosslinkable perfluorinated ion exchange membrane: Take 1g of the formula

[0122]

[0123] A perfluorophosphate resin with Mn=900 was dissolved in a mixed solution of DMSO (5 ml) and isopropylamine (5 ml) at room temperature. After mixing evenly, 0.1 g of photosensitizing compound-6 was added, and the mixture was heated and stirred at 80 °C to dissolve. Then, 2 ml of deionized water was added, and the evenly mixed casting solution was poured onto a horizontally placed glass plate. The perfluorophosphate membrane that can be photocrosslinked was obtained by evaporation at 80 °C for 24 h.

[0124] (3) The perfluorinated ion exchange membrane obtained in (2) can be photocrosslinked under 365nm ultraviolet light, or local photocrosslinking can be achieved through a mask.

[0125] Example 7:

[0126] A photocrosslinkable perfluorinated ion exchange membrane is prepared by means of the following steps:

[0127] (1) Preparation of quaternized photosensitive small molecule compound: 2.20 g of 1-propylimidazolium and 4.54 g of 9-chloromethylanthracene were mixed in 50 mL of acetone. Under nitrogen protection, the mixture was heated to 56 °C and refluxed for 10 h. After the reaction was completed, the mixture was cooled to room temperature and precipitated with anhydrous diethyl ether. The solid obtained was filtered and dried to obtain a pale yellow powdery solid product, namely the quaternized photosensitive small molecule compound-7, with a yield of approximately 90%.

[0128] (2) Preparation of photocrosslinkable perfluorinated ion exchange membrane: Take 1g of the formula

[0129]

[0130] A perfluorosulfonic acid resin with Mn=1200 was dissolved in a mixed solution of DMF (5 ml) and isopropylamine (5 ml) at room temperature. After mixing evenly, 0.1 g of photosensitive compound-7 was added, and the mixture was heated and stirred at 80 °C to dissolve. Then, 2 ml of deionized water was added, and the evenly mixed casting solution was poured onto a horizontally placed glass plate. The perfluoro ion exchange membrane that can be photocrosslinked was obtained by evaporation at 80 °C for 24 h.

[0131] (3) The perfluorinated ion exchange membrane obtained in (2) can be photocrosslinked under 365nm ultraviolet light, or local photocrosslinking can be achieved through a mask.

[0132] Example 8:

[0133] A photocrosslinkable perfluorinated ion exchange membrane is prepared by means of the following steps:

[0134] (1) Preparation of quaternized photosensitive small molecule compound: 3.01 g of 4-(2-dimethylaminoethyl)pyridine and 9.07 g of 9-chloromethylanthracene were mixed in 50 mL of DMF. Under nitrogen protection, the mixture was heated to 80 °C and reacted for 10 h. After the reaction was completed, the mixture was cooled to room temperature, precipitated with DMF, filtered, and the resulting solid was dried to obtain a pale yellow powdery solid product, namely the quaternized photosensitive small molecule compound-8, with a yield of approximately 80%.

[0135] (2) Preparation of photocrosslinkable perfluorinated ion exchange membranes. Take 1g of the formula...

[0136]

[0137] A perfluorophosphate resin with Mn=1000 was dissolved in a mixed solution of DMSO (5 ml) and isopropylamine (5 ml) at room temperature. After mixing evenly, 0.1 g of photosensitive compound-8 was added, and the mixture was heated and stirred at 80 °C to dissolve. Then, 2 ml of deionized water was added, and the evenly mixed casting solution was poured onto a horizontally placed glass plate. The perfluorophosphate membrane that can be photocrosslinked was obtained by evaporation at 80 °C for 24 h.

[0138] (3) The perfluorinated ion exchange membrane obtained in (2) can be photocrosslinked under 365nm ultraviolet light, or local photocrosslinking can be achieved through a mask.

[0139] As can be seen from the above results, the advantages of the perfluorinated ion exchange membrane according to the present invention are: (1) It is simple to manufacture and does not require complicated chemical synthesis. By mixing the perfluorinated ion exchange resin with the photocrosslinkable small molecule compound in a solvent and evaporating the solvent by casting, a film with uniform texture can be obtained; (2) It has good dispersion stability and strong universality. Based on physical crosslinking, the photocrosslinkable small molecule compound can form ionic bonds with the acidic groups between the perfluorinated ion exchange resin, which helps the molecule to be dispersed inside the ion exchange membrane; based on photochemical reaction, the photochemical crosslinking of the functional groups in the photocrosslinkable small molecule causes chemical crosslinking to occur inside the material, which further improves the mechanical strength of the material; (3) It has a high degree of freedom in selecting the crosslinking region. Based on the photocrosslinkable functional groups, the crosslinking region can be freely controlled by controlling the ultraviolet light exposure area.

[0140] Exemplary but non-limiting implementations are as follows:

[0141] Implementation Method 1. A photocrosslinkable perfluorinated ion exchange membrane, characterized in that it is obtained by mixing a perfluorinated ion exchange resin containing sulfonic acid groups or phosphate groups as the film-forming resin with a quaternized photosensitive compound.

[0142] Embodiment 2. The photocrosslinkable perfluorinated ion exchange membrane according to Embodiment 1, wherein the quaternized photosensitive compound is obtained by a quaternization reaction of a compound containing a tertiary amine group and a photosensitive compound.

[0143] Embodiment 3. The photocrosslinkable perfluorinated ion exchange membrane according to Embodiment 2, wherein the compound containing tertiary amine groups has the structural formula shown in formula (1):

[0144]

[0145] Wherein, X1 and X2 are independently selected from tertiary amine, imidazole, and pyridine groups, respectively; a and b are integers and are independently selected from 0 or 1, but cannot both be 0; and R1 is C1-C2. 20 Straight-chain or branched alkyl groups.

[0146] Embodiment 4. The photocrosslinkable perfluorinated ion exchange membrane according to Embodiment 3, wherein the compound containing a tertiary amine group is selected from trimethylamine, triethylamine, tributylamine, N,N-dimethylethylamine, N,N-dimethylhexylamine, N,N-dimethyln-octylamine, N,N-dimethyldecylamine, N,N-dimethyldodecylamine, N,N-dimethyltetradecylamine, N,N,N,N-tetramethyl-1,6-hexanediamine, dodecylbenzylmethylamine, N-methyldicyclohexylamine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2-propylpyridine, 3-propylpyridine, 4-propylpyridine, 2-butylpyridine, 3-butylpyridine, 4-butylpyridine, 2-pentylpyridine, 3-pentylpyridine 4-Pentylpyridine, 1,2-bis(4-pyridyl)ethane, 4-(2-dimethylaminoethyl)pyridine, 1-methylimidazolium, 2-methylimidazolium, 3-methylimidazolium, 4-methylimidazolium, 1-ethylimidazolium, 2-ethylimidazolium, 3-ethylimidazolium, 4-ethylimidazolium, 1-propylimidazolium, 2-propylimidazolium, 3-propylimidazolium, 4-propylimidazolium, preferably selected from trimethylamine, N,N-dimethylethylamine, N,N-dimethylhexylamine, N,N-dimethyln-octylamine, N,N-dimethyldecylamine, N,N-dimethyldodecylamine, N,N-dimethyltetradecylamine, N,N,N,N-tetramethyl-1,6-hexanediamine, 4-n-propylpyridine, 1,2-bis(4-pyridyl)ethane, 4-(2-dimethylaminoethyl)pyridine, and 1-propylimidazolium.

[0147] Embodiment 5. A photocrosslinkable perfluorinated ion exchange membrane according to any one of Embodiments 2 to 4, wherein the photosensitive compound is selected from one or more of the following formulas:

[0148]

[0149] X3, X4, and X5 are halogens; R2 and R7 are Cl-C. 20 Straight-chain or branched alkyl groups; R3, R4, R5, and R6 are each independently selected from hydrogen, C1-C6, C2-C4, C3-C4, C5-C6, C6 ... 20 Straight-chain or branched alkyl groups, C1-C 20 Alkoxy, nitro, hydroxy, nitrile, ester, cycloalkyl, phenyl, or naphthyl; n1, n2, n3, and n4 are integers between 0 and 4.

[0150] Embodiment 6. The photocrosslinkable perfluorinated ion membrane according to Embodiment 5, wherein the photosensitive compound is selected from halogenated anthracene, coumarin, and cinnamic acid compounds.

[0151] Embodiment 7. A method for preparing the photocrosslinkable perfluorinated ion-exchange membrane according to any one of Embodiments 1 to 6, comprising the following steps:

[0152] (1): A compound containing a tertiary amine group is mixed with a photosensitive compound in an organic solvent to obtain a mixed solution;

[0153] (2): The mixed solution is heated and stirred under an inert gas atmosphere, and the compound containing the tertiary amine group undergoes a quaternization reaction with the photosensitive compound;

[0154] (3): The product was precipitated from the resulting reaction mixture using a poor solvent, and then obtained by filtration and drying to obtain the quaternized photosensitive compound;

[0155] (4): Dissolve the quaternized photosensitive compound and the perfluorinated ion exchange resin in a mixed solvent, mix them evenly, and then evaporate the solvent to obtain a photocrosslinkable perfluorinated ion membrane.

[0156] Implementation Method 8. According to the method of Implementation Method 7, wherein in step (1), the molar ratio between the photosensitive compound and the compound containing the tertiary amine group is 1:1 to 6:1.

[0157] Implementation Method 9. The method according to Implementation Method 7 or 8, wherein the organic solvent used in step (1) is selected from one or more of ketones, 1,4-dioxane, dimethyl sulfoxide, N,N-dimethylformamide, or N,N-dimethylacetamide.

[0158] Implementation 10. The method according to any one of Implementations 7 to 9, wherein the inert gas in step (2) is nitrogen or argon.

[0159] Implementation Method 11. The method according to any one of Implementation Methods 7 to 10, wherein the reaction time in step (2) is 8-48 h and the reaction temperature is 50-130 °C.

[0160] Implementation Method 12. The method according to any one of Implementation Methods 7 to 11, wherein the undesirable solvent in step (3) is selected from one or more of alcohols, ethers, water, and lipids.

[0161] Embodiment 13. The method according to any one of Embodiments 7 to 12, wherein the perfluorinated ion exchange resin is a perfluorosulfonic acid resin, a perfluorophosphate resin, or a combination thereof.

[0162] Implementation Method 14. The method according to any one of Implementation Methods 7 to 13, wherein the mixed solvent in step (5) is two or more of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, ethylenediamine, propylenediamine, butanediamine, pentanediamine, isopropylamine, water, and ethanol.

[0163] Implementation Method 15. The method according to any one of Implementation Methods 7 to 14, wherein the solvent evaporation temperature in step (4) is 10-200°C and the evaporation time is 0.5-48h.

[0164] All disclosures of patents, patent applications, publications, and electronically available materials cited herein are incorporated herein by reference. The foregoing detailed descriptions and embodiments are provided for clarity only and should not be construed as unnecessarily limiting. The invention is not limited to the precise details shown and described; obvious variations to those skilled in the art will be included within the scope of the invention as defined by the claims.

[0165] In some embodiments, the invention disclosed illustratively herein may be practiced in the absence of any element not explicitly disclosed herein. Although the invention has been described with reference to numerous embodiments and examples, those skilled in the art will recognize that other embodiments can be devised based on the disclosure of this invention without departing from the scope and spirit of the invention.

Claims

1. A photo-crosslinkable perfluorinated ion membrane, characterized in that, obtained by mixing a perfluoro ion exchange resin containing a sulfonic acid group or a phosphoric acid group with a quaternary aminated photosensitive compound obtained by quaternary amination of a compound containing a tertiary amine group and a photosensitive compound; the compound containing a tertiary amine group has a structural formula shown in formula (1): Formula (1) wherein X1, X2are independently selected from tertiary amines, imidazoles, pyridine groups, a, b are integers and independently selected from 0 or 1, but cannot be 0 at the same time, R1is C1-C 20 linear or branched alkyl; and the photosensitive compound is selected from one or more of the following formulas: Formula (2) Formula (3) Formula (4) wherein X3, X4, X5are halogens; R2and R7are C1-C 20 linear or branched alkyl; R3, R4, R5, R6are independently selected from hydrogen, C1-C 20 linear or branched alkyl, C1-C 20 alkoxy, nitro, hydroxy, nitrile, ester, cycloalkyl, phenyl or naphthyl; n1, n2and n3are integers between 0 and 4.

2. The photo-crosslinkable perfluorinated ion membrane according to claim 1, wherein, the compound containing a tertiary amine group is selected from trimethylamine, triethylamine, tributylamine, N,N-dimethylethylamine, N,N-dimethylhexylamine, N,N-dimethyl-n-octylamine, N,N-dimethyldecylamine, N,N-dimethyldodecylamine, N,N-dimethyltetradecylamine, N,N,N,N-tetramethyl-1,6-hexanediamine, dodecylbenzylmethylamine, N-methyldicyclohexylamine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2-propylpyridine, 3-propylpyridine, 4-propylpyridine, 2-butylpyridine, 3-butylpyridine, 4-butylpyridine, 2-pentylpyridine, 3-pentylpyridine, 4-pentylpyridine, 1,2-bis(4-pyridyl)ethane, 4-(2-dimethylaminoethyl)pyridine, 1-methylimidazole, 2-methylimidazole, 3-methylimidazole, 4-methylimidazole, 1-ethylimidazole, 2-ethylimidazole, 3-ethylimidazole, 4-ethylimidazole, 1-propylimidazole, 2-propylimidazole, 3-propylimidazole, 4-propylimidazole.

3. The photo-crosslinkable perfluorinated ion membrane according to claim 1, wherein, the compound containing a tertiary amine group is selected from trimethylamine, N,N-dimethylethylamine, N,N-dimethylhexylamine, N,N-dimethyl-n-octylamine, N,N-dimethyldecylamine, N,N-dimethyldodecylamine, N,N-dimethyltetradecylamine, N,N,N,N-tetramethyl-1,6-hexanediamine, 4-n-propylpyridine, 1,2-bis(4-pyridyl)ethane, 4-(2-dimethylaminoethyl)pyridine, 1-propylimidazole.

4. A method for preparing the photo-crosslinkable perfluoro ion membrane according to any one of claims 1 to 3, comprising the following steps: (1): mixing a compound containing a tertiary amine group and a photosensitive compound in an organic solvent to obtain a mixed solution; (2): heating and stirring the mixed solution under an inert gas atmosphere, and quaternary aminating the compound containing a tertiary amine group and the photosensitive compound; (3): precipitating the product from the obtained reaction mixed solution with a poor solvent, and obtaining the quaternary aminated photosensitive compound by filtration and drying; (4): dissolving the quaternary aminated photosensitive compound and the perfluoro ion exchange resin in a mixed solvent, uniformly mixing, and obtaining the photo-crosslinkable perfluoro ion membrane by evaporating the solvent.

5. The method according to claim 4, wherein in step (1), the molar ratio between the photosensitive compound and the compound containing a tertiary amine group is 1:1 to 6:

1.

6. The method of claim 4 or 5, wherein the organic solvent used in step (1) is selected from one or more of ketones, 1,4-dioxane, dimethyl sulfoxide, N,N- dimethylformamide, or N,N-dimethylacetamide.

7. The method of claim 4 or 5, wherein the inert gas in step (2) is nitrogen or argon.

8. The method of claim 4 or 5, wherein the reaction time in step (2) is 8-48 h and the reaction temperature is 50-130 °C.

9. The method of claim 4 or 5, wherein the poor solvent in step (3) is selected from one or more of alcohols, ethers, water, lipids.

10. The method of claim 4 or 5, wherein the perfluorinated ion exchange resin is a perfluorinated sulfonic acid resin, a perfluorinated phosphoric acid resin, or a combination thereof.

11. The method of claim 4 or 5, wherein the mixed solvent in step (4) is two or more of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, ethylenediamine, propylenediamine, butylenediamine, pentanediamine, isopropylamine, water, ethanol.

12. The method of claim 4 or 5, wherein the solvent evaporation temperature in step (4) is 10-200 °C and the evaporation time is 0.5-48 h.

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