Olefin-based tertiary amine monomers for crosslinked anion exchange membranes and methods of making the same

Abstract

The application discloses an olefin-based tertiary amine monomer for a crosslinked anion exchange membrane and a preparation method and application thereof. The monomer structure is shown in a general formula: (R a)(R b)N-R c, wherein R a and R b are each independently selected from an alkyl group, an aryl group, a heterocyclic group or an alkenyl group, R c is a group containing at least one alkenyl group, and at least two groups of R a, R b and R c each contain at least one alkenyl group. The preparation method comprises the following steps: halogenating a tertiary alcohol amine to obtain a halogenated tertiary amine, and then reacting the halogenated tertiary amine with a Grignard reagent prepared from a halogenated olefin to obtain the target monomer. The monomer contains multiple alkenyl groups and tertiary amine groups in the molecule, can be used as a precursor with polymerizable and ionizable functions, and is used for preparing an anion exchange membrane with a three-dimensional network crosslinked structure. The raw material is easy to obtain, the synthesis route is simple, the product structure is adjustable, the prepared anion exchange membrane has high ionic conductivity, excellent dimensional stability and alkali resistance, and is suitable for alkaline fuel cells, water electrolysis hydrogen production and other electrochemical devices.

Description

Technical Field

[0001] This invention relates to the field of polymer functional materials and electrochemical membrane materials, specifically to an olefin-based tertiary amine monomer for cross-linked anion exchange membranes and its preparation method, as well as the anion exchange membrane prepared from the monomer and its application in electrochemical devices. Background Technology

[0002] Anion exchange membranes (AEMs) are key components in energy conversion and storage devices such as alkaline fuel cells (AFCs), water electrolysis for hydrogen production (AEMWE), electrodialysis, and carbon dioxide electrochemical reduction. Their performance, especially ionic conductivity, mechanical strength, dimensional stability, and alkali chemical stability, directly determines the efficiency and lifespan of the device.

[0003] Traditional anion exchange membranes are mostly based on linear or side-chain polymers, such as quaternized derivatives of polysulfone, polyphenylene ether, and polyolefins. During long-term operation, especially in high-temperature and high-alkali environments, these membranes are prone to severe ion swelling, decreased mechanical properties, and Hofmann degradation of quaternary ammonium groups, leading to rapid performance degradation.

[0004] To overcome the above-mentioned defects, cross-linked anion exchange membranes have attracted much attention due to their three-dimensional network structure, which can effectively suppress swelling and enhance mechanical and dimensional stability. The core of constructing such membranes lies in designing and synthesizing functional monomers with multiple reactive functional groups (such as double bonds). However, the functional monomers that can be used to construct cross-linked networks in the prior art often have the following problems: (1) the synthesis route is complicated, the steps are lengthy, and the overall yield is low; (2) the raw materials are expensive, especially monomers containing specific aromatic rings or heterocyclic structures; (3) the monomer structure is simple, the adjustability is poor, and it is difficult to achieve precise control of the membrane cross-linking density and microstructure; (4) while ensuring cross-linkability, it is difficult to take into account the high density of ion conduction sites.

[0005] Therefore, developing a novel, easy-to-synthesize, low-cost, and multifunctional crosslinking monomer that can simultaneously provide polymerizable and ion-conducting sites is of great significance for promoting the development of high-performance, long-life anion exchange membranes.

[0006] Based on the above reasons, this application is hereby submitted. Summary of the Invention

[0007] Based on the above reasons, the primary objective of this invention is to provide a novel olefin-based tertiary amine monomer containing at least two alkenyl groups within its molecule, which can serve as a key precursor for constructing a three-dimensional network cross-linked anion exchange membrane. This invention also provides an efficient and low-cost method for preparing the aforementioned monomer.

[0008] To achieve the above-mentioned objectives of the present invention, the technical solution adopted by the present invention is as follows: An olefinic tertiary amine monomer for use in cross-linked anion exchange membranes, the structure of which is shown in general formula (I): (R a (R) b )NR c (I) in, R a and R b Each is independently selected from alkyl, aryl, heterocyclic, or alkenyl groups; R c It is a group containing at least one alkenyl group; And R a R b and R c At least two groups in the mixture each contain at least one alkenyl group.

[0009] Preferably, the R c The group has the structure of formula (II): R d CH=CH-( Ar ) m ( CH 2) n - (II) Among them, R d H or alkyl, Ar is phenyl, substituted phenyl or aromatic heterocyclic; m is 0 or 1; n is an integer from 0 to 20.

[0010] Furthermore, in the above technical solution, the olefin-based tertiary amine monomer is prepared by reacting a halo-tertiary amine with a Grignard reagent containing an olefin group.

[0011] Furthermore, in the above technical solution, the halo-tertiary amine is prepared by reacting the corresponding tertiary alcohol amine with a chlorinating reagent, wherein the chlorinating reagent includes thionyl chloride, phosphorus trichloride, phosphorus pentachloride, and phosphorus oxychloride, etc.

[0012] Furthermore, in the above technical solution, the tertiary alcohol amine is characterized by having a structure as shown in general formula (I): (R 1 (R) 2 )NR 3 (III) in, R 1 and R 2 Each is independently selected from hydroxylated alkyl, aryl, or heterocyclic groups; R 3 It is a group containing at least one alcohol hydroxyl group; And R 1 R 2 and R 3 At least two groups in the mixture each contain at least one alcohol hydroxyl group.

[0013] Furthermore, the above-mentioned technical solution, the method for preparing the halotergamine, is characterized by comprising the following steps: S1: Under ice bath conditions, tertiary alcohol amines are reacted with chlorinating agents in one or more mixed solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, or dimethyl sulfoxide to prepare chlorotertiary amine hydrochloride. The molar ratio of tertiary alcohol amine to chlorinating agent is 1:3.5-4.0, the reaction temperature is 0-60℃, and the reaction time is 4-6 hours.

[0014] S2: The hydrochloride obtained in step (1) is alkalized with sodium hydroxide solution, and then extracted, dried and purified to obtain free chlorinated tertiary amine. The alkali used for alkalization is sodium hydroxide or potassium hydroxide, and the amount of alkali used is 1.2-1.8 times the molar amount of hydrochloride.

[0015] Furthermore, in the above technical solution, the Grignard reagent containing an olefin group is prepared by reacting dried chloroolefins with metallic magnesium in anhydrous diethyl ether or anhydrous tetrahydrofuran. The preparation of the Grignard reagent is carried out under argon protection, at a reaction temperature of 30-50℃, and for a reaction time of 1-2 hours.

[0016] Furthermore, in the above technical solution, the olefinic tertiary amine monomer is characterized by reacting the dried halo-tertiary amine with a Grignard reagent, quenching the reaction with an alkaline solution, and then extracting, drying, and concentrating to obtain the target monomer. The reaction between the Grignard reagent and the halo-tertiary amine is carried out in anhydrous diethyl ether for 2-12 hours at a temperature ranging from room temperature to 0-40°C.

[0017] Furthermore, in the above technical solution, the obtained olefin-based tertiary amine monomer is reacted with a haloalkane to obtain an olefin-based quaternary ammonium salt, which is then used in a polymerization reaction to prepare a cross-linked anion exchange membrane resin. The haloalkane includes chloroalkane, bromoalkane, and iodoalkane, and the number of alkyl carbons is 1-16.

[0018] Furthermore, in the above technical solution, the anion exchange membrane is used in electrochemical devices, including alkaline fuel cells, water electrolysis hydrogen production devices, or electrodialysis equipment.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. The monomer of this invention integrates polymerizable alkenyl groups with ionizable / crosslinkable tertiary amines and haloalkyl groups. At least two alkenyl groups ensure the formation of a crosslinked network during polymerization; the tertiary amine readily undergoes quaternization to form ion-conducting sites; the haloalkyl groups can participate in quaternization and also serve as additional crosslinking points, achieving functional integration. 2. It can be efficiently prepared using inexpensive and readily available alkanolamines and haloolefins as the main starting materials through mature halogenation and Grignard reactions, with a short route, high overall yield, and suitability for large-scale production. 3. By changing the structure of the tertiary alkanolamine (e.g., using alkanolamines with different chain lengths) or selecting different alkenyl-containing Grignard reagents, the flexibility, hydrophobicity, ion exchange capacity (IEC), and crosslinking density of the monomer can be flexibly controlled, thereby meeting the membrane performance requirements of different application scenarios. 4. The crosslinked anion exchange membrane prepared from this monomer is expected to have high ionic conductivity, excellent mechanical strength, low swelling ratio, and good alkali chemical stability, significantly improving the performance and lifespan of related electrochemical devices. 5. The prepared anion exchange membrane can be widely used in the field of energy electrochemistry, where ion conduction and stability requirements are stringent. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the synthetic route for the intermediate trichloroethylamine hydrochloride in a preferred embodiment of the present invention.

[0022] Figure 2 This is a physical image of the intermediate free tri-2-chloroethylamine in a preferred embodiment of the present invention.

[0023] Figure 3 In a preferred embodiment of the present invention, the ¹H NMR spectrum of the intermediate free tri-2-chloroethylamine is shown.

[0024] Figure 4 This is a schematic diagram of the synthetic route of the intermediate 4-ethylenebenzenemethylmagnesium chloride Grignard reagent in a preferred embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the synthetic route for the final product, tris(4-vinylphenylpropylamine), in a preferred embodiment of the present invention.

[0026] Figure 6This is a photograph of experimental phenomena during the synthesis of the final product, tris(4-ethylenephenylpropylamine), in a preferred embodiment of the present invention.

[0027] Figure 7 In a preferred embodiment of the present invention, the ¹H NMR spectrum of the final product tris(4-vinylphenylpropylamine) is shown. Detailed Implementation

[0028] The present invention will be further described in detail below through implementation examples. These implementation examples are carried out based on the technology of the present invention. Detailed implementation methods and specific operating procedures are provided to illustrate the inventiveness of the present invention, but the scope of protection of the present invention is not limited to the following implementation examples.

[0029] Based on the information contained in this application, various modifications to the precise description of the invention can be readily made by those skilled in the art. It should be understood that the scope of the invention is not limited to the defined processes, properties, or components, as these embodiments and other descriptions are merely illustrative of specific aspects of the invention.

[0030] To better understand the invention and not to limit its scope, all figures indicating amounts, percentages, and other numerical values ​​used in this application should, in all cases, be understood to be modified by the word "approximately." Therefore, unless otherwise stated, the numerical parameters listed in the specification are approximate values ​​and may vary depending on the desired properties being sought. Each numerical parameter should at least be considered as obtained based on reported significant figures and through conventional rounding methods.

[0031] The equipment and raw materials used in this invention are all commercially available or commonly used in the field. Unless otherwise specified, the methods in the following embodiments are conventional methods in the field.

[0032] This patent uses readily available and inexpensive triethanolamine and 4-chloromethylstyrene as starting materials for illustrative purposes. The method specifically includes the following steps: (1) Synthesis of trichloroethylamine hydrochloride like Figure 1 As shown, triethanolamine (23.66 g, 0.16 mol) and DMF (25 ml, 20 wt%) were added to a 250 ml three-necked flask. Thionyl chloride (42 ml, 3.9 eq) was added dropwise using a constant-pressure dropping funnel. The reaction was carried out in an ice-water bath, and after the addition was complete, the reaction temperature was maintained at 60 °C for 4 hours. After cooling, the reaction solution was transferred to 60 ml of anhydrous ethanol and stirred for 2 hours. The mixture was then placed in a refrigerator to crystallize. The crystals were collected by suction filtration and dried at 80 °C for 12 hours to obtain 21.2593 g of a white precipitate, with a yield of 55.6%.

[0033] (2) Preparation of free tri-2-chloroethylamine Dissolve 18.5680 g of hydrochloride in 10 ml of deionized water and transfer to a separatory funnel. Dissolve 4.6039 g of sodium hydroxide (1.5 eq) in 20 ml of deionized water and add it to the separatory funnel. Collect the lower organic phase. Extract the aqueous phase three times with 5 ml of diethyl ether. Combine the extracted organic phases with the previous organic phases and dry with anhydrous magnesium sulfate overnight. Filter the dried liquid and reflux with calcium hydride at 40 °C for 4 h. Filter again and rotary evaporate to obtain 15.5847 g of a colorless to pale yellow liquid. (See image below.) Figure 2 As shown, the yield was 98.9%. 1 HNMR test results are as follows Figure 3 As shown, the peaks at chemical shifts of 3.59 and 2.93 correspond to the two hydrogens of the methylene group, respectively, proving the successful synthesis of the free amine tri-2-chloroethylamine.

[0034] (3) Preparation of Grignard reagent for 4-ethylenebenzyl magnesium chloride The preparation method of 4-vinylbenzyl magnesium chloride Grignard reagent is as follows: Figure 4 As shown. Weigh 0.2704 g (0.11 mol) of magnesium shavings and place them in a three-necked flask. Weigh 1.6404 g (0.1 mol) of 4-chloromethylstyrene and mix them with 10 ml of diethyl ether solution. Add the mixture to a constant pressure dropping funnel. First, add 1-2 ml of the mixed solution and add a grain of iodine. Heat to 40°C. When the color gradually changes from brown to grayish-black, slowly add the remaining solution to the reaction mixture. React for half an hour under nitrogen protection.

[0035] (4) Preparation of tris(4-vinylphenylpropylamine) The preparation process of tris(4-vinylphenylpropylamine) is as follows: Figure 5 As shown. After the Grignard reagent reaction was complete, the free amine from the first step, tris(2-chloroethylamine) (0.6940 g, 3 mmol), was added, and the reaction was maintained for 11 hours. Layering was observed, as shown. Figure 6 As shown, the upper layer is a yellow liquid, and the lower layer is a grayish-white precipitate. Then, 0.1536 g of NaOH (1.25 eq) was weighed, dissolved in 10 ml of deionized water, and added to a three-necked flask for quenching. After filtration, the filtrate was added to a separatory funnel, and the upper organic layer of diethyl ether was collected. The aqueous phase was extracted three times with diethyl ether, dried with anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain 1.6284 g of yellow liquid. 1 HNMR test results are as follows Figure 7 As shown, the peaks with chemical shifts of 7.35 and 7.16 correspond to hydrogens on the benzene ring, respectively; chemical shifts of 6.69, 5.76, and 5.19 correspond to hydrogens in the carbon-carbon double bond; and chemical shift of 3.59 corresponds to the methylene peak. The appearance of these peaks and their integrated areas prove that the synthesis of tris(4-ethylenephenylpropylamine) was successful.

Claims

1. An olefin-based tertiary amine monomer for use in cross-linked anion exchange membranes and its preparation method, characterized in that, Its structure is shown in general formula (I): (R a )(R b )N-R c (I) in, R a and R b Each is independently selected from alkyl, aryl, heterocyclic, or alkenyl groups; R c It is a group containing at least one alkenyl group; And R a R b and R c At least two groups in the mixture each contain at least one alkenyl group.

2. The monomer according to claim 1, characterized in that, The R c The group has the structure of formula (II): R d CH=CH-( Ar ) m ( CH 2) n - (II) Among them, R d H or alkyl, Ar is phenyl, substituted phenyl or aromatic heterocyclic; m is 0 or 1; n is an integer from 0 to 20.

3. The olefinic tertiary amine monomer according to claim 1 is prepared by reacting a halo-tertiary amine with an olefinic Grignard reagent.

4. The halo-tertiary amine according to claim 3 is prepared by reacting the corresponding tertiary alcohol amine with a chlorinating agent, wherein, Chlorination reagents include thionyl chloride, phosphorus trichloride, phosphorus pentachloride, and phosphorus oxychloride.

5. A tertiary alcoholamine as described in claim 4, characterized in that, Its structure is shown in general formula (I): (R 1 )(R 2 )NR 3 (III) in, R 1 and R 2 Each is independently selected from hydroxylated alkyl, aryl, or heterocyclic groups; R 3 It is a group containing at least one alcohol hydroxyl group; And R 1 R 2 and R 3 At least two groups in the mixture each contain at least one alcohol hydroxyl group.

6. A method for preparing a halotergamine as described in claim 3, characterized in that, Includes the following steps: S1: Under ice bath conditions, tertiary alcohol amine is reacted with a chlorinating agent in one or more mixed solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, or dimethyl sulfoxide to prepare chlorotertiary amine hydrochloride. The molar ratio of tertiary alcohol amine to chlorinating agent is 1:3.5-4.0, the reaction temperature is 0-60℃, and the reaction time is 4-6 hours. S2: The hydrochloride obtained in step (1) is alkalized with sodium hydroxide solution, and then extracted, dried, and purified to obtain free chlorotertiary amine. The alkali used for alkalization is sodium hydroxide or potassium hydroxide, and the amount of alkali used is 1.2-1.8 times the molar amount of hydrochloride.

7. The Grignard reagent containing an olefin group according to claim 3 is prepared by reacting a dried chloroolefin with metallic magnesium in anhydrous diethyl ether or anhydrous tetrahydrofuran. The preparation of the Grignard reagent is carried out under argon protection at a reaction temperature of 30-50°C for 1-2 hours.

8. The olefinic tertiary amine monomer according to claim 1, characterized in that... The halo-tertiary amine free amine prepared according to claim 5 was dried and then reacted with the Grignard reagent prepared according to claim 6. After the reaction was completed, it was quenched with alkaline solution, and the target monomer was obtained by extraction, drying and concentration. The reaction of Grignard reagent with halo-tertiary amine free amine is carried out in anhydrous diethyl ether for 2-12 hours at a temperature ranging from room temperature to 0-40°C.

9. The olefinic tertiary amine monomer according to claim 1, characterized in that... The obtained olefin-based tertiary amine monomer will react with a haloalkane to obtain an olefin-based quaternary ammonium salt, which will be used in the polymerization reaction to prepare cross-linked anion exchange membrane resin. The haloalkane includes chloroalkane, bromoalkane, and iodoalkane, and the number of alkyl carbons is 1-16.

10. An application of the anion exchange membrane as described in claim 9 in an electrochemical device, wherein the electrochemical device includes an alkaline fuel cell, a water electrolysis hydrogen production device, an electrodialysis device, an osmosis and reverse osmosis device, etc.

Images