Photo-curing anion exchange membrane as well as preparation method and application thereof

Abstract

The invention discloses a photocuring anion-exchange membrane and a preparation method and application thereof, and relates to the technical field of anion-exchange membranes and preparation thereof. The photoinitiator comprises the following components in parts by mass: 50-80 parts of an acrylate polymer matrix containing an epoxy group, 10-30 parts of an anion exchange group functional monomer, 1-5 parts of a photoinitiator, 2-10 parts of a cross-linking agent and 0.5-5 parts of an additive. The membrane shows excellent mechanical strength and chemical stability in hydrogen production through water electrolysis, the curing efficiency is improved by two times or more compared with a traditional process through a deuterated photo-initiation system of the membrane, the ionic conduction efficiency is remarkably enhanced through the synergistic effect of a three-dimensional cross-linked network and graphene filler, and the technical bottleneck that a traditional anion exchange membrane is prone to swelling and short in service life is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of anion exchange membranes and their preparation, and particularly relates to a photocurable anion exchange membrane, its preparation method and application. Background Art

[0002] Anion exchange membranes are widely used in many fields such as energy and chemical industry, especially in the field of hydrogen production by electrolysis of water. Their performance directly affects the hydrogen production efficiency and cost. The traditional preparation of anion exchange membranes mostly uses a thermal curing process, which has many limitations.

[0003] On the one hand, the thermal curing process takes a long time, needs to be maintained at a relatively high temperature for a long time, has high energy consumption and low production efficiency, and is difficult to meet the needs of large-scale industrial rapid production, increasing the preparation cost. On the other hand, the performance of traditional anion exchange membranes needs to be improved. Their mechanical strength is limited. In application scenarios such as hydrogen production by electrolysis of water, facing the complex electrolyte solution environment and the stress generated by electrode reactions, they are prone to problems such as deformation and rupture, affecting the stable operation of equipment and shortening the service life. The chemical stability is also not ideal. When in a harsh chemical environment such as strong alkalinity for a long time, it is prone to degradation, resulting in a decrease in ion conduction performance, an increase in conduction resistance, an aggravation of energy loss, and ultimately limiting the overall efficiency and economic benefits of hydrogen production by electrolysis of water.

[0004] In addition, some traditional preparation methods have deficiencies in raw material selection and process flow. Some raw materials are scarce or costly, and the process is complex, involving multiple steps of cumbersome operations, strict parameter control, and high requirements for production equipment. These factors all restrict the wide application and further development of anion exchange membranes. There is an urgent need to develop new and efficient preparation technologies to break through the existing bottlenecks and promote the technological upgrading and industrial progress of related fields. Summary of the Invention

[0005] The purpose of the present invention is to address the problems existing in the prior art, and aims to provide a photocurable anion exchange membrane with high efficiency, high mechanical strength, good chemical stability and a fast and energy-saving preparation process, as well as its preparation method and application.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is: a photocurable anion exchange membrane, which includes the following components according to mass parts: 50-80 parts of an acrylate polymer matrix containing epoxy groups, 10-30 parts of an anion exchange group functional monomer, 1-5 parts of a photoinitiator, 2-10 parts of a crosslinking agent, and 0.5-5 parts of an additive;

[0007] The additive includes at least one of a toughening agent, a conductive filler and / or an antioxidant;

[0008] The photoinitiator has the structure shown in Formula 1:

[0009] Formula 1;

[0010] R1 - R2 are the same or different and are selected from: alkyl groups having 1 - 5 carbon atoms, alkoxy groups having 1 - 5 carbon atoms, aryl groups having 6 - 15 carbon atoms, deuterated alkyl groups having 1 - 5 carbon atoms, deuterated aryl groups having 6 - 15 carbon atoms;

[0011] Z1 is selected from: -O-, -S-, -N(R3)-, -C(R4)(R4)-;

[0012] R3 is selected from: methyl, tert - butyl, phenyl, deuterated methyl, deuterated tert - butyl, deuterated phenyl;

[0013] R4 is selected from: methyl, phenyl, deuterated methyl, deuterated phenyl.

[0014] Furthermore, R1 - R2 are the same or different and are selected from: methyl, tert - butyl, phenyl, deuterated methyl, deuterated tert - butyl, deuterated phenyl.

[0015] Furthermore, the structure represented by Formula 1 is selected from Formula 2 - Formula 5:

[0016] Formula 2;

[0017] Formula 3;

[0018] Formula 4;

[0019] Formula 5.

[0020] Furthermore, the photoinitiator is at least one of the compounds represented by the following structures:

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028] ;

[0029] where D represents deuterium.

[0030] Furthermore, the synthesis method of the photoinitiator is as follows:

[0031] ;

[0032] The first step: Raw material 1 and raw material 2 undergo Buchwald-Hartwig arylation reaction to generate intermediate 1;

[0033] The second step: Intermediate 1 and raw material 3 undergo substitution reaction to generate intermediate 2;

[0034] The third step: Intermediate 2 undergoes hydroxyamination to generate intermediate 3;

[0035] The fourth step: Intermediate 3 and raw material 4 undergo substitution reaction to generate the photoinitiator.

[0036] Furthermore, the acrylate polymer matrix containing epoxy groups is selected from one or more of bisphenol A diglycidyl ether acrylate, epoxy acrylate resin, and polybutadiene acrylic epoxy ester.

[0037] Furthermore, the anionic exchange group functional monomer is selected from dimethylaminoethyl methacrylate quaternary ammonium salt and / or vinylbenzyltrimethylammonium chloride.

[0038] Furthermore, the crosslinking agent is selected from diacrylate and / or trimethylolpropane triacrylate.

[0039] Furthermore, the toughening agent is nano-silica.

[0040] Furthermore, the conductive filler is graphene; the antioxidant is 2,6-tert-butyl-4-methylphenol and / or bis(3,5-tert-butyl-4-hydroxyphenyl) sulfide.

[0041] A preparation method of a photocurable anionic exchange membrane includes the following steps:

[0042] S1. Mix the acrylate polymer matrix containing epoxy groups, anionic exchange group functional monomer, photoinitiator, crosslinking agent, and additive according to the mass ratio, and dissolve them in an organic solvent to form a homogeneous slurry;

[0043] S2. Coat the slurry on the surface of the substrate, pre-bake it at 40-80 °C for 5-30 minutes to form a pre-cured film;

[0044] S3. Irradiate the pre-cured film with ultraviolet light, the light intensity is 10-100 mW / cm 2 , and the exposure time is 1-10 minutes to obtain a cured film;

[0045] S4. Peel the cured film from the substrate, soak it in a 0.1 - 1 mol / L hydrochloric acid solution for 1 - 5 hours, wash it with deionized water until neutral, and dry it to obtain a photocured anion exchange membrane.

[0046] Furthermore, the organic solvent is at least one of N,N - dimethylformamide, N - methylpyrrolidone, or acetone, and the solid content of the slurry is 20% - 50%.

[0047] Furthermore, the ultraviolet light wavelength is 250 - 400 nm, and the exposure process is carried out in a nitrogen atmosphere.

[0048] Furthermore, the substrate is a glass plate, a silicon wafer, or a polyethylene terephthalate plate.

[0049] Application of a photocured anion exchange membrane in hydrogen production by electrolyzing water.

[0050] The core structure of the photoinitiator described in the present invention is essentially a highly efficient photosensitive conjugate system. Its core function is to rapidly generate free radicals through ultraviolet light excitation. The conjugate structure of the core (such as an aromatic ring or a heterocyclic ring) has ultraviolet absorption ability in a wide wavelength range, which is highly matched with the wavelength of the ultraviolet light source, ensuring efficient light energy capture. The heteroatoms (O / S / N) in Z1 can enhance the intramolecular charge transfer effect, reduce the excited state energy, promote the intersystem crossing from the singlet state to the triplet state, and prolong the lifetime of free radical generation. After illumination, the core absorbs photons and jumps to the excited state, generating active free radicals through α - cleavage or hydrogen extraction reactions. The bond energy of the C - D bond is higher than that of the C - H bond, the bond length is shorter, and the vibration frequency is reduced. This significantly slows down the non - radiative decay of the photoinitiator in the excited state, prolongs the triplet state lifetime, and increases the probability of free radical generation. Deuterated aryl / alkyl can inhibit the side reaction of photodegradation and reduce the self - consumption of the photoinitiator during the curing process. In a nitrogen atmosphere, deuterated alkyl can reduce the rate of hydrogen extraction reaction, reduce the generation of ineffective free radicals caused by the participation of H atoms in the solvent or polymer, and make the cured network denser.

[0051] The free radicals generated by the photoinitiator described in the present invention preferentially attack the double bond of acrylate to initiate chain polymerization. The epoxy group opens the ring in the acidic post - treatment stage to form ion exchange sites, and together with the quaternary ammonium group of the anion functional monomer, constructs an ion channel. The multi - functionality design of diacrylate / trimethylolpropane triacrylate matches the high - efficiency free radical generation rate of the photoinitiator, ensuring the formation of a three - dimensional cross - linked network in a short time and enhancing the mechanical strength of the membrane. Nano - silica disperses stress through hydrogen bonding between the surface hydroxyl groups and the polymer matrix; the π - π stacking of graphene generates electron coupling with the aromatic ring core, reducing the surface resistance of the membrane.

[0052] If the photoinitiator described in the present invention is replaced with a non-conjugated structure (such as aliphatic ketones), the ultraviolet absorption red shift is insufficient and cannot match the 250-400 nm light source, resulting in a decrease in curing efficiency. Compared with the traditional thermal curing, the photo-curing process (pre-baking at 40-80 °C + UV curing) reduces energy consumption, and the high reactivity of the parent nucleus structure is the core to achieve low-temperature and rapid curing.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0054] 1. The curing efficiency is significantly improved: Through the design of the photosensitive conjugated system of the deuterated photoinitiator, the light energy utilization efficiency is improved.

[0055] 2. The material properties are comprehensively optimized: The densification degree of the three-dimensional cross-linked network is improved, and the synergistic effects of the toughening agent and the conductive filler are combined, so that the mechanical strength and chemical stability are enhanced simultaneously, and the anti-swelling and anti-degradation capabilities are improved.

[0056] 3. The adaptability of the application performance is enhanced: The degree of orderly arrangement of the ion channels inside the cured film is improved, and the ion conduction efficiency and the durability under the electrolysis condition are optimized simultaneously, which is more suitable for the high-current density electrolytic water hydrogen production scenario. Description of the Drawings

[0057] Figure 1 It is the synthesis route of the photoinitiator described in the present invention. Detailed Embodiments

[0058] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0059] Preparation Example 1

[0060] Synthesis of photoinitiator:

[0061] ;

[0062] In the first step, under nitrogen protection, 20 g of raw material 1 and 27.87 g of raw material 2 were added to the reaction system in sequence, dissolved in toluene solution, 15.56 g of sodium tert-butoxide, 0.7 g of tri(dibenzylideneacetone)dipalladium, and 0.8 g of tri-tert-butylphosphine were added, stirred evenly, heated to 120°C, and refluxed for 12 hours; after the reaction was completed, the temperature was slightly lowered, filtered with diatomaceous earth to remove salt and catalyst, the filtrate was cooled to room temperature, washed three times with water, the organic phase was retained, and then the aqueous phase was extracted with ethyl acetate; after the organic phases were combined, they were dried with anhydrous magnesium sulfate, and the solvent was removed with a rotary evaporator; dissolved in petroleum ether / ethanol, recrystallized, filtered, the filter cake was rinsed with petroleum ether for multiple times, and dried in a 60°C oven for 7 hours to obtain 31.16 g of intermediate 1. MS[MS+1]: 511.

[0063] Step 2: Under nitrogen protection, 31.16 g of intermediate 1 and 9.76 g of aluminum chloride were added to the reaction system in sequence, and 300 ml of dichloromethane was added. 9.58 g of formyl chloride dissolved in 50 ml of dichloromethane solution was slowly added dropwise under an ice-water bath, and reacted at room temperature for 6-8 hours. After the reaction was completed, 100 ml of 0.2 mol / L HCl at 0°C was added, stirred, and allowed to stand. The organic phase was retained, and the aqueous phase was washed with dichloromethane for 2-3 times. The organic phases were combined, and the pH of the system was adjusted to neutral with a dilute sodium bicarbonate aqueous solution. The organic phase was retained, passed through a silica gel cake, and spun to dryness to obtain 24.21 g of intermediate 2. MS [MS+1]: 553.

[0064] Step 3: Under nitrogen protection, 24.21 g of intermediate 2, 4.57 g of hydroxylamine hydrochloride and 5.39 g of sodium acetate were added to the reaction system in sequence, and 200 g of tetrahydrofuran was added to react for 6-12 h. After the reaction was complete as detected by TLC, the reaction solution was added to 1000 ml of water, kept at 0° C. overnight, and filtered to obtain a powdery solid. The powdery solid was dissolved in 100 ml of tetrahydrofuran, and 20 g of anhydrous magnesium sulfate was added to dry, filtered, rotary evaporated, and dried to obtain 19.12 g of intermediate 3. MS [MS+1]: 568.

[0065] Step 4: Under nitrogen protection, 19.12 g of intermediate 3 and 3.17 g of acetyl chloride were successively added into the reaction system, 200 ml of dichloromethane was added, 6.82 g of triethylamine was slowly added dropwise at 0 °C, the temperature was raised to room temperature, and the reaction was carried out at room temperature for 4 - 6 hours. After confirming that the reaction was complete, 500 ml of water at 0 °C was slowly added dropwise and stirred for 1 hour. Then, it was left to stand for liquid separation and the organic phase was retained. The pH of the organic phase was adjusted to neutral with 0.1 mol / L dilute hydrochloric acid, washed with water once and the organic phase was retained again, dried with 30 g of anhydrous magnesium sulfate, and spun into a viscous liquid; this viscous liquid was dissolved in 100 ml of ethanol, heated under reflux for 1 h, cooled to room temperature, and then a white solid product was precipitated. After filtration and drying, the final product was obtained, and 17.13 g of the final product was obtained. MS[MS + 1]: 610.

[0066] Preparation Examples 2 - 5

[0067] For the compounds synthesized in Preparation Examples 2 - 5, referring to the preparation method of Preparation Example 1, raw material 1 was replaced, and the rest was the same as in the examples. The specific structures of raw material 1, compound structures, and MS[MS + 1] data are shown in the following table.

[0068] 。

[0069] 。

[0070] Example 1

[0071] A preparation method of a photocurable anion exchange membrane, comprising the following steps:

[0072] S1. Mix the acrylate polymer matrix containing epoxy groups (epoxy acrylate resin, 50 - 80 parts), anion exchange group functional monomer (dimethylaminoethyl methacrylate quaternary ammonium salt, 10 - 30 parts), photoinitiator (synthesized in Preparation Example 1, 1 - 5 parts), crosslinking agent (diacrylate, 2 - 10 parts), and additive (nano - silica, 0.5 - 5 parts) according to the mass ratio, and dissolve them in an organic solvent to form a homogeneous slurry;

[0073] S2. Coat the slurry on the surface of the substrate, pre - bake at 40 - 80 °C for 5 - 30 minutes to form a pre - cured film;

[0074] S3. Irradiate the pre - cured film with ultraviolet light, the light intensity is 10 - 100 mW / cm 2 , and the exposure time is 1 - 10 minutes to obtain a cured film;

[0075] S4. Peel the cured film from the substrate, soak it in a 0.1 - 1 mol / L hydrochloric acid solution for 1 - 5 hours, wash it with deionized water until neutral, and dry it to obtain a photocurable anion exchange membrane.

[0076] Examples 2 - 5

[0077] For the preparation of a photocurable anion exchange membrane, referring to the preparation method described in Example 1, the photoinitiator therein was sequentially replaced with the photoinitiators synthesized in Preparation Examples 2 - 5, and the rest was kept the same as in Example 1.

[0078] Comparative Example 1

[0079] For the preparation of a photocurable anion exchange membrane, referring to the preparation method described in Example 1, the photoinitiator therein was replaced with Comparative Compound 1, and the rest was kept the same as in Example 1.

[0080] The structure of the Comparative Compound 1 is: .

[0081] Comparative Example 2

[0082] For the preparation of a photocurable anion exchange membrane, referring to the preparation method described in Example 1, the photoinitiator therein was not added, and the rest was kept the same as in Example 1.

[0083] Performance test:

[0084] 1. Photocuring time test: The pre-cured membrane was irradiated with an ultraviolet light curing instrument (wavelength 365 nm, light intensity 50 mW / cm 2 ), and the change in the characteristic peak intensity of the acrylate double bond at 1630 cm -1 was monitored by real-time infrared spectroscopy (RT-FTIR). When the double bond conversion rate ≥ 95%, the shortest exposure time required was recorded as the photocuring time.

[0085] 2. Ion conductivity test: The cured membrane was immersed in 1 mol / L KOH solution for 24 hours, taken out and clamped between two stainless steel electrodes, and the in-plane ion conductivity of the membrane was measured using an electrochemical workstation (frequency range: 1 Hz - 1 MHz). The calculation formula is: . Where L is the membrane thickness (cm), R is the impedance spectrum fitting resistance (Ω), and S is the electrode contact area (cm 2 ).

[0086] .

[0087] Examples using the photoinitiator of the present invention show significant advantages compared to the comparative examples. In terms of photocuring efficiency, the example group exhibits a shorter curing response cycle, and its curing rate is about 2-3 times higher than that of the traditional non-deuterated structure initiation system, demonstrating that the deuterated group effectively improves the light energy utilization rate by inhibiting non-radiative decay. In terms of ionic conductivity, the example group shows better charge transport ability, and the quality of its ion channel formation is significantly better than that of the comparative example, which is attributed to the synergistic effect of the dense cross-linked network promoted by the deuterated photoinitiator and the ordered arrangement of anion groups. In Comparative Example 1, the increase in curing network defects due to low initiation efficiency, while the complete three-dimensional cross-linked structure of the example group provides a continuous path for ion transport.

[0088] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A photocurable anion exchange membrane, characterized in that, It comprises the following components by mass parts: 50 - 80 parts of an acrylate polymer matrix containing epoxy groups, 10 - 30 parts of an anionic exchange group functional monomer, 1 - 5 parts of a photoinitiator, 2 - 10 parts of a crosslinking agent, and 0.5 - 5 parts of an additive; The additive includes at least one of a toughening agent, a conductive filler, and / or an antioxidant; The photoinitiator has the structure shown in Formula 1: Formula 1; R1 - R2 are the same or different and are selected from: alkyl groups with 1 - 5 carbon atoms, alkoxy groups with 1 - 5 carbon atoms, aryl groups with 6 - 15 carbon atoms, deuterated alkyl groups with 1 - 5 carbon atoms, deuterated aryl groups with 6 - 15 carbon atoms; Z1 is selected from: -O-, -S-, -N(R3)-, -C(R4)(R4)-; R3 is selected from: methyl, tert - butyl, phenyl, deuterated methyl, deuterated tert - butyl, deuterated phenyl; R4 is selected from: methyl, phenyl, deuterated methyl, deuterated phenyl.

2. The photocurable anion exchange membrane according to claim 1, wherein R1 - R2 are the same or different and are selected from: methyl, tert - butyl, phenyl, deuterated methyl, deuterated tert - butyl, deuterated phenyl.

3. The photocurable anion exchange membrane according to claim 1, wherein, The structure shown in Formula 1 is selected from: Formula 2; Formula 3; Formula 4; Formula 5.

4. The photocurable anion exchange membrane according to claim 1, characterized in that The photoinitiator is at least one of the compounds shown by the following structures: ； ； ； ； ； ； ； ； Where D represents deuterium.

5. The photocurable anion exchange membrane according to claim 1, wherein The acrylate polymer matrix containing epoxy groups is selected from one or more of bisphenol A diglycidyl ether acrylate, epoxy acrylate resin, and polybutadiene acrylic epoxy ester; The anionic exchange group functional monomer is selected from dimethylaminoethyl methacrylate quaternary ammonium salt and / or vinylbenzyltrimethylammonium chloride; The crosslinking agent is selected from diacrylate and / or trimethylolpropane triacrylate.

6. The photocurable anion exchange membrane according to claim 1, wherein The toughening agent is nano - silica; the conductive filler is graphene; the antioxidant is 2,6 - tertiary - butyl - 4 - methylphenol and / or bis(3,5 - tertiary - butyl - 4 - hydroxyphenyl) sulfide.

7. A method for preparing a photocurable anion exchange membrane according to any one of claims 1-6, characterized in that, It includes the following steps: S1. Mix the acrylate polymer matrix containing epoxy groups, anionic exchange group functional monomer, photoinitiator, crosslinking agent, and additive according to the mass parts ratio, and dissolve them in an organic solvent to form a homogeneous slurry; S2. Coat the slurry on the surface of the substrate, pre - bake it at 40 - 80 °C for 5 - 30 minutes to form a pre - cured film; S3. Irradiate the pre-cured film with ultraviolet light at a light intensity of 10 - 100 mW / cm 2 , with an exposure time of 1 - 10 minutes, to obtain a cured film; S4. Peel the cured film from the substrate, soak it in a 0.1 - 1 mol / L hydrochloric acid solution for 1 - 5 hours, wash it with deionized water until neutral, and dry it to obtain a photocurable anion - exchange membrane.

8. The preparation method of a photocurable anion exchange membrane according to claim 7, characterized in that, The organic solvent is at least one of N,N - dimethylformamide, N - methylpyrrolidone, or acetone, and the solid content of the slurry is 20% - 50%; The wavelength of the ultraviolet light is 250 - 400 nm, and the exposure process is carried out in a nitrogen atmosphere.

9. The preparation method of a photocurable anion exchange membrane according to claim 7, characterized in that, The substrate is a glass plate, a silicon wafer, or a polyethylene terephthalate plate.

10. Application of a photocurable anion - exchange membrane according to any one of claims 1 - 6 in hydrogen production by electrolysis of water.

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