Photo-crosslinking polyion liquid and preparation method thereof

Abstract

The invention discloses photo-crosslinking type polyion liquid and a preparation method thereof, and belongs to the technical field of functional materials. The method comprises the following steps: firstly, synthesizing a halide containing a coumarin unit, then carrying out quaternization reaction on the halide containing the coumarin unit and a bis-imidazole compound to prepare a bis-imidazole ionic liquid monomer containing the coumarin unit, and then carrying out ultraviolet radiation and anion exchange to prepare the photo-crosslinking type polyionic liquid. The invention provides a novel method for preparing the polyionic liquid, and ionic liquid units are uniformly positioned in a framework of the polyionic liquid. The novel imidazole polyionic liquid prepared by adopting a photo-crosslinking method can realize reversible conversion of cracking and polymerization under the condition of regulation and control of illumination, so that a new way is provided for regulation and control and application of material performance. The invention provides a new thought for development and research of solid or quasi-solid electrolyte.

Description

Technical Field

[0001] This invention relates to a photocrosslinked polyionic liquid and its preparation method, belonging to the field of functional materials technology. Background Technology

[0002] Polyionic liquids (PILs) are novel ionic polymers synthesized from monomers incorporating ionic liquid-related functional groups (cations such as imidazolium, pyrrolomium, and pyridinium, and anions such as tetrafluoroborate, hexafluorophosphate, and trifluoroate). PILs possess some of the properties of ionic liquids, including low volatility, non-flammability, high thermal stability, good conductivity, and a wide electrochemical window; they also retain the structure and morphology of polymers, maintaining plasticity and mechanical strength. As a novel material, PILs have broad application potential in batteries, capacitors, and solid-state electrolytes. They can be used to prepare high-performance battery electrolytes, improving the electrochemical performance and cycle stability of batteries; in capacitors, PIL-based electrolytes can increase specific capacitance and energy density while maintaining high power density. Furthermore, they have also attracted widespread attention in various fields such as sensors, catalysis, composite materials, and gas separation membranes. (Zhu M, Yang Y. Poly(ionic liquid)s: anemerging platform for green chemistry. Green Chemistry. 2024; Ren H, He X, Long Y, Li Q, Li S, Zhou

[0003] Due to the variety of polymer backbones and the diversity of ionic groups, polyionic liquids (PIPs) offer high designability, greatly expanding their performance possibilities to meet various requirements in different fields. Currently, PIPs are mainly obtained through free radical polymerization of ionic liquid monomers containing unsaturated bonds, or through free radical copolymerization of polymerizable ionic liquid monomers and other polymerizable monomers. Patent CN202210140216.2 discloses an imidazole-based PIP and its preparation method, which involves polymerizing vinyl imidazoles with different anions under conventional free radical polymerization conditions. Patent CN202010311225.4 discloses a solvent-free in-situ photopolymerized PIP electrolyte, which is produced by polymerizing vinyl-containing polymerizable ionic liquid monomers and polyethylene glycol dimethacrylate (PEGDMA) under UV light. The resulting PIP has a low proportion of ionic liquid units, and the different polymerization rates of the ionic liquid and PEGDMA affect the uniformity of the polymer chain. In the reported structures of polyionic liquids, the ionic liquid structural units mainly exist in the side chains, and are rarely found in the main chain backbone.

[0004] This invention provides a novel photocrosslinked polyionic liquid and its preparation method. The polyionic liquid is prepared by synthesizing a bisimidazole ionic liquid monomer containing coumarin units from hydroxyl-containing coumarin compounds, dihaloalkanes or aliphatic ethers, imidazole, etc., followed by ultraviolet light irradiation and anion exchange. Coumarins and their derivatives undergo a two-phase reaction under certain wavelengths of light.

[0005] Polymerization reactions, which can be reversibly photodegraded by 254nm ultraviolet light irradiation, are often used as photoresponsive materials in research (Sana B, Ferrentino N, Kohlan TB, Liu Y, Pasiskevicius V, Finne-Wistmnd A, Pappalardo D. Coumarin end-capped poly(ε-caprolactone)-poly(ethylene glycol) tri-block copolymer: synthesis, characterization and light-response behavior. European Polymer Journal. 2023, 183: 111760). The polyionic liquid of this invention has ionic liquid units located in the polymer backbone and has a uniform structure. The polyionic liquid of this invention can achieve reversible degradation and polymerization under controlled light irradiation conditions, thus providing a new approach for the regulation and application of material properties. This invention provides a new approach for the development and research of solid-state or quasi-solid-state electrolytes. Summary of the Invention

[0006] Purpose of the invention: The first purpose of this invention is to provide a novel photocrosslinked polyionic liquid, and the second purpose is a method for preparing the photocrosslinked polyionic liquid.

[0007] Technical solution:

[0008] The photocrosslinked polyionic liquid of the present invention has the following general structural formula:

[0009]

[0010] Where A = C3H6, C4H8, C5H 10 C6H 12 C2H4OC2H4, C2H4OC2H4OC2H4, a type of CH2(C6H4)CH2;

[0011] B = C3H6, C4H8, C5H 10 C6H 12 , C2H4OC2H4, C2H4OC2H4OC2H4, one of CH2(C6H4)CH2; R=H, one of CH3; X=one of bis(trifluoromethanesulfonyl)imide, hexafluorophosphate, tetrafluoroborate, dicyandiamide, bromide, or chloride; n=10-100.

[0012] The method for preparing the photocrosslinked polyionic liquid of the present invention includes the following steps:

[0013] (1) Synthesis of halogenated compounds containing coumarin units

[0014] Using hydroxyl-containing coumarin compounds and dihalogenated compounds as raw materials, and organic or inorganic bases as alkalis, the reaction is carried out in an organic solvent under reflux at 50-100℃ for 2-12 hours to prepare halogenated compounds CX containing coumarin units.

[0015] (2) Synthesis of diimidazole compounds

[0016] The diimidazole compound MRM was prepared by reacting sodium or potassium salt of imidazole with a dihalogenated compound for 1-3 hours.

[0017] (3) Synthesis of coumarin-containing diimidazole ionic liquid monomers

[0018] The halogenated compound CX obtained in step (1) and the diimidazole compound MBM obtained in step (2) were refluxed in an organic solvent at 50-100℃ for 8-36h to obtain the diimidazole ionic liquid monomer CMRMC containing coumarin units.

[0019] (4) Synthesis of polyionic liquids

[0020] The compound CMRMC from step (3) was dissolved in a solvent and irradiated with light at 310-370 nm for 4-30 h to prepare a polyionic liquid with different anions by ion exchange.

[0021] Further, the hydroxyl-containing coumarin compound mentioned in step (1) is one of 7-hydroxycoumarin, 6-hydroxycoumarin, 6-hydroxy-4-methylcoumarin, and 7-hydroxy-4-methylcoumarin; the dihalogenated compound is one of 1,3-dibromopropane, 1,4-dibromobutane, 1,5-dibromopentane, 1,6-dibromohexane, 1-bromo-2-(2-bromoethoxy)ethane, 1,2-bis(2-bromoethoxy)ethane, p-dibromobenzyl, 1,3-dichloropropane, 1,4-dichlorobutane, 1,5-dichloropentane, 1,6-dichlorohexane, 1-chloro-2-(2-chloroethoxy)ethane, 1,2-bis(2-chloroethoxy)ethane, and p-dichlorobenzyl.

[0022] Further, the organic base mentioned in step (1) is triethylamine, piperidine, or pyridine; the inorganic base is anhydrous potassium carbonate or anhydrous sodium carbonate; and the organic solvent is one of 1,4-dioxane, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, or tetrahydrofuran.

[0023] Further, in step (1), the molar ratio of the hydroxyl-containing coumarin compound to the dihalogenated product is (1-1.2):1; the molar ratio of the hydroxyl-containing coumarin compound to the alkali agent is 1:(0.8-1.1).

[0024] Further, in step (2), the dihalogenated compound is one of 1,3-dibromopropane, 1,4-dibromobutane, 1,5-dibromopentane, 1,6-dibromohexane, 1-bromo-2-(2-bromoethoxy)ethane, 1,2-bis(2-bromoethoxy)ethane, p-dibromobenzyl, 1,3-dichloropropane, 1,4-dichlorobutane, 1,5-dichloropentane, 1,6-dichlorohexane, 1-chloro-2-(2-chloroethoxy)ethane, 1,2-bis(2-chloroethoxy)ethane, and p-dichlorobenzyl.

[0025] Further, in step (2), the molar ratio of imidazole sodium salt or potassium salt to dihalogenated product is (2-2.3):1.

[0026] Further, in step (3), the molar ratio of the halogenated compound CX to the diimidazole compound MRM is 2:(0.8-1.0);

[0027] Further, in step (4), the solvent is one or two of methanol, ethanol, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, and dichloromethane.

[0028] Further, in step (4), the anion is one of bis(trifluoromethanesulfonyl)imide, hexafluorophosphate, tetrafluoroborate, dicyandiamide, bromide, or chloride.

[0029] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0030] 1. This invention employs a photocrosslinking method to prepare novel imidazole-based polyionic liquids. These polyionic liquids can achieve reversible decomposition and polymerization under controlled light irradiation conditions, thus providing a new approach for the regulation and application of material properties.

[0031] 2. This invention provides a new method for preparing polyionic liquids, wherein the ionic liquid units are uniformly located in the framework of the polyionic liquid, and the resulting novel polyionic liquids enrich the types and quantities of polyionic liquids.

[0032] Instruction manual illustrations

[0033] Figure 1 1H NMR spectrum of 7-(4-bromobutoxy)-4-methylcoumarin

[0034] Figure 2 7-(4-bromobutoxy)-4-methylcoumarin C NMR spectrum

[0035] Figure 3 1,1′-(1,4-butyl)diimidazole 1H NMR spectrum

[0036] Figure 4 1,1′-(1,4-butyl)diimidazole C NMR spectrum

[0037] Figure 5 3,3′-bis[4-oxo-(4-methyl-2H-benzopyran-2-one)]butyl]-1,1′-(1,4-butyl)bisimidazole bromide 1H NMR spectrum

[0038] Figure 6 3,3′-bis[4-oxo-(4-methyl-2H-benzopyran-2-one)]butyl]-1,1′-(1,4-butyl)-bisimidazole bromide carbon NMR spectrum Detailed Implementation

[0039] The technical solution of the present invention will be further described below with reference to the embodiments.

[0040] Example 1

[0041] (1) Synthesis of 7-(4-bromobutoxy)-4-methylcoumarin

[0042] 120 mL of acetonitrile was added to a 250 mL four-necked flask, followed by 24 mmol of 1,4-dibromobutane, 25 mmol of anhydrous K₂CO₃, and 24 mmol of 7-hydroxy-4-methylcoumarin. The mixture was refluxed at 81 °C with stirring for 6 h. The reaction was monitored by thin-layer chromatography. Stirring was stopped, the mixture was cooled to room temperature, filtered, and the filtrate was evaporated by rotary evaporation. Recrystallization yielded 7-(4-bromobutoxy)-4-methylcoumarin, with the following structural formula:

[0043]

[0044] 1H NMR spectrum of (4-bromobutoxy)-4-methylcoumarin (400 MHz, DMSO-d6): 7.52 ppm (d, 1H), 6.85 ppm (q, 1H), 6.81 ppm (d, 1H), 6.14 ppm (d, 1H), 4.07 ppm (t, 2H), 3.51 ppm (t, 2H), 2.41 ppm (d, 3H), 2.10 ppm (m, 2H), 2.01 ppm (m, 2H).

[0045] 1C NMR spectrum (100MHz, DMSO-d6) of (4-bromobutoxy)-4-methylcoumarin: 162.04ppm, 160.58ppm, 155.18ppm, 153.79ppm, 126.83ppm, 113.51ppm, 112.85ppm, 111.55ppm, 101.58ppm, 67.85ppm, 35.19ppm, 29.44ppm, 27.63ppm, 18.58ppm.

[0046] (2) Synthesis of 1,1′-(1,4-butyl)bisimidazole

[0047] In a 100 ml three-necked round-bottom flask, 0.1 mol imidazole and 0.1 mol sodium hydroxide were added. The mixture was reacted openly at 110 °C for 1 h to obtain a pale yellow solid product. Then, 40 ml isopropanol, a trace amount of tetrabutylammonium bromide, and 0.05 mol 1,4-dibromobutane were added. The mixture was refluxed and stirred at 85 °C for 2 h. After cooling to room temperature, the mixture was filtered, and the filtrate was rotary evaporated and recrystallized from pure water to obtain a white solid product, 1,1′-(1,4-butyl)bisimidazole, with the following structural formula:

[0048]

[0049] 1H NMR spectrum of 1,1′-(1,4-butyl)bisimidazole (400 MHz, DMSO-d6): 7.61 ppm (s, 2H), 7.14 ppm (s, 2H), 6.88 ppm (s, 2H), 3.96 ppm (m, 4H), 1.62 ppm (m, 4H)

[0050] 1,1′-(1,4-butyl)diimidazole C NMR spectrum (100MHz, DMSO-d6): 137.66ppm, 128.82ppm, 119.71ppm, 45.74ppm, 28.12ppm.

[0051] (3) Synthesis of the ionic liquid monomer CBIMB of bisimidazole coumarin

[0052] In a 250 ml four-necked flask, 4 mmol of 7-(4-bromobutoxy)-4-methylcoumarin, 2 mmol of 1,1′-(1,4-butyl)diimidazole, and 40 ml of acetonitrile were added. The mixture was refluxed and stirred at 81 °C for 24 h. The solvent was removed by rotary evaporation, and recrystallization yielded a white solid, namely the diimidazole coumarin ionic liquid monomer CBIMB, with the following structural formula:

[0053]

[0054] CBIMB's hydrogen nuclear magnetic spectrum (400MHz, DMSO-d6): 9.42ppm (s, 2H), 7.88ppm (d, 2H), 7.81ppm (d, 2H), 7.66ppm (d, 2H), 6.96ppm (d, 2H), 6.94ppm (q, 2H), 6.21ppm (q, 2H), 4,31ppm (t, 4H), 4.29ppm (t, 4H), 4.12ppm (m, 4H), 2.39ppm (d, 6H), 1.99ppm (m, 4H), 1.83ppm (m, 4H), 1.75ppm (m, 4H)

[0055] CBIMB's nuclear magnetic carbon spectrum (100MHz, DMSO-d6): 161.96ppm, 161.49ppm, 160.59ppm, 155.14ppm, 153.86ppm, 136.65ppm. 126.92ppm, 122.96pp m,113.56ppm, 112.85ppm, 111.59ppm, 101.64ppm, 68.06ppm, 49.02ppm, 48.52ppm, 26.65ppm, 26.51ppm, 25.60ppm, 18.62ppm.

[0056] (4) Synthesis of polyionic liquid P[CBIMB]TFSI

[0057] Dissolve 0.49 g of CBIMB in 4 ml of methanol. After irradiating the solution with ultraviolet light for 12 h, add a methanol solution containing 1.4 mmol of lithium bis(trifluoromethanesulfonyl)imide. Stir thoroughly, remove the supernatant, and wash the product with water until no bromide ions are present in the washings (tested with silver nitrate). After drying, the polyionic liquid P[CBIMB]TFSI is obtained, with the following structure:

[0058]

[0059] Example 2

[0060] (1) Synthesis of 7-(2-(2-bromoethoxy)ethoxy)-4-methylcoumarin

[0061] 100 mL of acetonitrile was added to a 250 mL four-necked flask, followed by 24 mmol of 1-bromo-2-(2-bromoethoxy)ethane, 25 mmol of anhydrous K₂CO₃, and 24 mmol of 7-hydroxy-4-methylcoumarin. The mixture was refluxed at 81 °C with stirring for 8 h (the reaction was monitored by thin-layer chromatography). Stirring was stopped, the mixture was cooled to room temperature, filtered, and the filtrate was evaporated by rotary evaporation. Recrystallization yielded 7-(2-(2-bromoethoxy)ethoxy)-4-methylcoumarin, with the following structural formula:

[0062]

[0063] 1H NMR spectrum of 7-(2-(2-bromoethoxy)ethoxy)-4-methylcoumarin (400 MHz, DMSO-d6):

[0064] 7.68ppm (d, 1H), 6.99ppm (d, 1H), 6.97ppm (q, 1H), 6.21ppm (q, 1H), 4.23ppm (t, 2H), 3.82ppm (t, 2H), 3.80ppm (t, 2H), 3.62ppm (t, 2H), 2.39ppm (d, 3H).

[0065] 100 MHz, DMSO-d6 NMR spectrum of 7-(2-(2-bromoethoxy)ethoxy)-4-methylcoumarin: 161.98 ppm, 159.92 ppm, 158.92 ppm, 151.60 ppm, 126.71 ppm, 113.82 ppm, 112.31 ppm, 108.84 ppm, 105.68 ppm, 70.30 ppm, 69.52 ppm, 67.38 ppm, 30.25 ppm, 19.56 ppm.

[0066] (2) Synthesis of 1,1′-(1,4-butyl)bisimidazole

[0067] Same as Example 1(2)

[0068] (3) Synthesis of the diimidazole coumarin ionic liquid monomer CEOEIMB

[0069] In a 250 ml four-necked flask, 4 mmol of 7-(2-(2-bromoethoxy)ethoxy)-4-methylcoumarin, 2 mmol of 1,1′-(1,4-butyl)diimidazole, and 40 ml of acetonitrile were added. The mixture was refluxed at 81 °C with stirring for 24 h. The solvent was removed by rotary evaporation, and the product was recrystallized to obtain a white solid, which is the ionic liquid monomer CEOEIMB of diimidazole coumarin. Its structural formula is as follows:

[0070]

[0071] CEOEIMB's hydrogen nuclear magnetic spectrum (400MHz, DMSO-d6): 9.99ppm (s, 2H), 7.53ppm (d, 2H), 7.36ppm (d, 2H), 7.27ppm (d, 2H), 6.87ppm (d, 2H), 6.81ppm (q, 2H, ), 6.18ppm (q, 2H), 4,14ppm (t, 4H), 4.11ppm (t, 4H), 4.07ppm (m, 4H), 3.86ppm (m, 4H), 3.69ppm (t, 4H), 2.40ppm (d, 6H), 1.75ppm (m, 4H)

[0072] NMR carbon spectrum of CEOEIMB (100MHz, DMSO-d6): 162.26ppm, 161.49ppm, 154.52ppm, 151.36ppm, 138.01ppm, 128.24ppm. 126.90ppm, 121.47p pm,115.95ppm, 111.82ppm, 110.91ppm, 101.98ppm, 70.58ppm, 69.72ppm, 68.57ppm, 48.41ppm, 44.85ppm, 27.52ppm, 18.81ppm.

[0073] (4) Synthesis of polyionic liquid P[CEOEIMB]TFSI

[0074] Dissolve 0.51 g of CEOEIMB in 3 ml of acetone. After irradiating the solution with ultraviolet light for 16 h, add a methanol solution containing 1.4 mmol of lithium bis(trifluoromethanesulfonyl)imide. After thorough stirring, remove the supernatant and wash the product with water until no bromide ions are present in the washings (tested with silver nitrate). After drying, the polyionic liquid P[CEOEIMB]TFSI is obtained, with the following structure:

[0075]

[0076] Example 3

[0077] (1) Synthesis of 7-(5-bromopentoxy)-4-methylcoumarin

[0078] Add 80 mL of acetonitrile to a 250 mL four-necked flask, then add 24 mmol of 1,5-dibromopentane, 25 mmol of anhydrous K₂CO₃, and 24 mmol of 7-hydroxy-4-methylcoumarin. Reflux at 81 °C with stirring for 6 h (monitored by thin-layer chromatography). Stop stirring, cool to room temperature, filter, rotary evaporate the filtrate, and recrystallize to obtain 7-(5-bromopentoxy)-4-methylcoumarin, with the following structural formula:

[0079]

[0080] 1H NMR spectrum of 7-(5-bromopentoxy)-4-methylcoumarin (400 MHz, DMSO-d6): 7.55 ppm (d, 1H), 6.84 ppm (d, 1H), 6.82 ppm (q, 1H), 6.15 ppm (q, 1H), 4.06 ppm (t, 2H), 3.43 ppm (t, 2H), 2.42 ppm (d, 3H), 1.88 ppm (m, 2H), 1.71 ppm (m, 2H), 1.51 ppm (m, 2H).

[0081] 1C NMR spectrum (100MHz, DMSO-d6) of 7-(5-bromopentoxy)-4-methylcoumarin: 162.06ppm, 159.92ppm, 159.21ppm, 151.60ppm, 126.67ppm, 113.32ppm, 112.31ppm, 107.66ppm, 107.13ppm, 68.49ppm, 33.74ppm, 32.28ppm, 29.07ppm, 25.78ppm, 19.56ppm.

[0082] (2) Synthesis of 1,1′-(1,4-butyl)bisimidazole

[0083] Same as Example 1(2)

[0084] (3) Synthesis of the diimidazole coumarin ionic liquid monomer CPIMB

[0085] In a 250 mL four-necked flask, 4 mmol of 7-(5-bromopentoxy)-4-methylcoumarin, 2 mmol of 1,1′-(1,4-butyl)diimidazole, and 40 mL of acetonitrile were added. The mixture was refluxed and stirred at 81 °C for 24 h. The solvent was removed by rotary evaporation, and the product was recrystallized to obtain the diimidazole coumarin ionic liquid monomer CPIMB, whose structural formula is as follows:

[0086]

[0087] 1H NMR spectrum (400MHz, DMSO-d6) of the diimidazole coumarin ionic liquid monomer CPIMB: 9.94 ppm (s, 2H), 7.55 ppm (d, 2H), 7.36 ppm (d, 2H), 7.26 ppm (d, 2H), 6.84 ppm (d, 2H), 6.82 ppm (q, 2H), 6.17 ppm (q, 2H), 4.15 ppm (t, 4H), 4.03 ppm (t, 4H), 2.41 ppm (d, 6H), 1.89 ppm (m, 4H), 1.73 ppm (m, 4H), 1.72 ppm (m, 4H), 1.49 ppm (m, 4H)

[0088] C1NMR spectra (100MHz, DMSO-d6) of the diimidazole coumarin ionic liquid monomer CPIMB: 161.44ppm, 161.41ppm, 154.51ppm, 151.36ppm, 137.35ppm, 128.30ppm, 126.60ppm, 121.55ppm, 115.87ppm, 111.81ppm, 110.91ppm, 101.99ppm, 68.84ppm, 48.56ppm, 48.41ppm, 30.53ppm, 29.11ppm, 27.52ppm, 23.61ppm, 18.87ppm.

[0089] (4) Synthesis of polyionic liquid P[CPIMB]Br

[0090] Dissolve 0.50 g of CEOEIMB in 3 ml of methanol. After irradiating the solution with ultraviolet light for 12 h, dry the solution to remove the solvent and obtain the polyionic liquid P[CPIMB]Br, whose structure is as follows:

[0091]

[0092] Example 4

[0093] (1) Synthesis of 7-(6-bromohexyloxy)-4-methylcoumarin

[0094] 100 mL of acetonitrile was added to a 250 mL four-necked flask, followed by 24 mmol of 1,6-dibromohexane, 25 mmol of anhydrous K₂CO₃, and 24 mmol of 7-hydroxy-4-methylcoumarin. The mixture was refluxed at 81 °C with stirring for 6 h (the reaction was monitored by thin-layer chromatography). Stirring was stopped, and the mixture was cooled to room temperature. The mixture was filtered, and the filtrate was evaporated by rotary evaporation. Recrystallization yielded 7-(6-bromohexoxy)-4-methylcoumarin, with the following structural formula:

[0095]

[0096] 1H NMR spectrum of 7-(6-bromohexyloxy)-4-methylcoumarin (400 MHz, DMSO-d6):

[0097] 7.56ppm (d, 1H), 6.84ppm (d, 1H), 6.82ppm (q, 1H), 6.15ppm (q, 1H,), 4.04ppm (t, 2H), 3.43pp m (t, 2H), 2.42ppm (d, 3H), 1.86ppm (m, 2H), 1.77ppm (m, 2H,) 1.48ppm (m, 2H), 1.46ppm (m, 2H)

[0098] 100 MHz, DMSO-d6 NMR spectrum of 7-(6-bromohexyloxy)-4-methylcoumarin: 162.17 ppm, 159.98 ppm, 159.21 ppm, 151.60 ppm, 126.64 ppm, 113.82 ppm, 112.23 ppm, 107.56 ppm, 107.13 ppm, 68.26 ppm, 33.85 ppm, 32.60 ppm, 29.22 ppm, 28.02 ppm, 25.42 ppm, 19.61 ppm.

[0099] (2) Synthesis of 1,1′-(1,4-butyl)bisimidazole

[0100] Same as Example 1(2)

[0101] (3) Synthesis of the diimidazole coumarin ionic liquid monomer CHIMB

[0102] 4 mmol of 7-(6-bromohexoxy)-4-methylcoumarin, 2 mmol of 1,1′-(1,4-butyl)diimidazole, and 40 ml of acetonitrile were added to a 250 ml four-necked flask. The mixture was refluxed and stirred at 81 °C for 24 h. The solvent was removed by rotary evaporation, and the solvent was used to wash the product to obtain the diimidazole coumarin ionic liquid monomer CHIMB, whose structural formula is as follows:

[0103]

[0104] 1H NMR spectrum (400 MHz, DMSO-d6) of the diimidazole coumarin ionic liquid monomer CHIMB: 9.94 ppm (s, 2H), 7.52 ppm (d, 2H), 7.36 ppm (d, 2H), 7.26 ppm (d, 2H), 6.88 ppm (d, 2H), 6.81 ppm (q, 2H), 6.18 ppm (q, 2H), 4.16 ppm (t, 4H), 4.05 ppm (t, 4H), 3.98 ppm (m, 4H), 2.41 ppm (d, 6H), 2.03 ppm (m, 4H), 1.76 ppm (m, 4H), 1.75 ppm (m, 4H), 1.53 ppm (m, 4H), 1.46 ppm (m, 4H)

[0105] Carbon NMR spectrum (100 MHz, DMSO-d6) of the diimidazole coumarin ionic liquid monomer CHIMB.

[0106] 161.49ppm, 161.47ppm, 154.51ppm, 151.35ppm, 137.35ppm, 128.28ppm. 126.58ppm, 121.49ppm, 115.95ppm, 111.81ppm, 110.91ppm, 102.00ppm, 68.86ppm, 48.55ppm, 48.41ppm, 30.65ppm, 29.06ppm, 27.52ppm, 26.10ppm, 25.94ppm, 18.81ppm.

[0107] (4) Synthesis of polyionic liquid P[CHIMB][PF6]

[0108] Dissolve 0.52 g CHIMB in 3 ml of methanol. After irradiating the solution with ultraviolet light for 12 h, add a methanol solution containing 1.4 mmol potassium hexafluorophosphate. Stir thoroughly, remove the supernatant, and wash the product with water until no bromide ions are present in the washings (tested with silver nitrate). After drying, the polyionic liquid P[CHIMB][PF6] is obtained, with the following structure:

[0109]

[0110] Example 5

[0111] (1) Synthesis of 7-(3-bromopropoxy)-4-methylcoumarin

[0112] 100 mL of acetonitrile was added to a 250 mL four-necked flask, followed by 24 mmol of 1,3-dibromopropane, 25 mmol of anhydrous K₂CO₃, and 24 mmol of 7-hydroxy-4-methylcoumarin. The mixture was refluxed at 81 °C with stirring for 5 h (the reaction was monitored by thin-layer chromatography). Stirring was stopped, the mixture was cooled to room temperature, filtered, and the filtrate was evaporated by rotary evaporation. Recrystallization yielded 7-(3-bromopropoxy)-4-methylcoumarin, with the following structural formula:

[0113]

[0114] 1H NMR spectrum of 7-(3-bromopropoxy)-4-methylcoumarin (400 MHz, DMSO-d6):

[0115] 7.43ppm (d, 1H), 6.84ppm (d, 1H), 6.78ppm (q, 1H), 6.08ppm (d, 1H), 4.12ppm (t, 2H), 3.59ppm (t, 2H), 2.46ppm (d, 3H), 2.32ppm (m, 2H).

[0116] 100 MHz, DMSO-d6 NMR spectrum of 7-(3-bromopropoxy)-4-methylcoumarin:

[0117] 162.68ppm, 161.57ppm, 154.73ppm, 153.05ppm, 127.63ppm, 113.39ppm, 111.36ppm, 110.39ppm, 102.78ppm, 66.98ppm, 32.46ppm, 30.06ppm, 20.10ppm.

[0118] (2) Synthesis of 1,1′-(1,4-butyl)bisimidazole

[0119] Same as Example 1(2)

[0120] (3) Synthesis of the ionic liquid monomer CPrIMB of diimidazole coumarin

[0121] 4 mmol of 7-(3-bromopropoxy)-4-methylcoumarin, 2 mmol of 1,1′-(1,4-butyl)diimidazole, and 40 ml of acetonitrile were added to a 250 ml four-necked flask. The mixture was refluxed and stirred at 81 °C for 24 h. The solvent was removed by rotary evaporation, and the solvent was used to wash the product to obtain the diimidazole coumarin ionic liquid monomer CPrIMB, the structural formula of which is as follows:

[0122]

[0123] 1H NMR spectrum (400 MHz, DMSO-d6) of the diimidazole coumarin ionic liquid monomer CPrIMB: 9.42 ppm (s, 2H), 7.88 ppm (d, 2H), 7.67 ppm (d, 2H), 7.43 ppm (d, 2H), 6.84 ppm (d, 2H), 6.77 ppm (q, 2H), 6.08 ppm (q, 2H), 4.67 ppm (t, 4H), 4.26 ppm (t, 4H), 4.06 ppm (m, 4H), 2.47 ppm (d, 6H), 2.46 ppm (m, 4H), 1.75 ppm (m, 4H).

[0124] The carbon NMR spectra (100 MHz, DMSO-d6) of the diimidazole coumarin ionic liquid monomer CPrIMB are as follows: 162.74 ppm, 161.57 ppm, 154.74 ppm, 153.05 ppm, 141.42 ppm, 127.63 ppm, 127.15 ppm, 123.96 ppm, 114.39 ppm, 111.41 ppm, 110.39 ppm, 102.72 ppm, 65.19 ppm, 53.73 ppm, 49.39 ppm, 30.94 ppm, 28.05 ppm, and 20.10 ppm.

[0125] (4) Synthesis of polyionic liquid P[CPrIMB][TFSI]

[0126] Dissolve 0.47 g of CPrIMB in 3 ml of acetonitrile. After irradiating the solution with ultraviolet light for 12 h, add a methanol solution containing 1.4 mmol of lithium bis(trifluoromethanesulfonyl)imide. After thorough stirring, remove the supernatant and wash the product with water until no bromide ions are present in the washings (tested with silver nitrate). After drying, the polyionic liquid P[CPrIMB][TFSI] is obtained, with the following structure:

[0127]

[0128] Example 6

[0129] (1) Synthesis of 7-(4-bromobutoxy)-4-methylcoumarin

[0130] Same as Example 1(1)

[0131] (2) Synthesis of 1,1′-(1,5-pentyl)diimidazole

[0132] In a 100 ml three-necked round-bottom flask, 0.1 mol imidazole and 0.1 mol sodium hydroxide were added. The mixture was reacted openly at 110 °C for 1 h to obtain a pale yellow solid product. Then, 40 ml isopropanol, a trace amount of tetrabutylammonium bromide, and 0.05 mol 1,5-dibromopentane were added. The mixture was refluxed and stirred at 85 °C for 2 h. After cooling to room temperature, the mixture was filtered, and the filtrate was rotary evaporated and recrystallized from pure water to obtain a white solid product, 1,1′-(1,5-pentyl)bisimidazole, with the following structural formula:

[0133]

[0134] 1H NMR spectrum of 1,1′-(1,5-pentyl)diimidazole (400 MHz, DMSO-d6):

[0135] 7.76ppm(s,2H), 7.18ppm(s,2H), 7.06ppm(q,2H), 3.94ppm(t,4H), 1.77ppm(m,4H)1.43ppm(m,2H)

[0136] 1,1′-(1,5-pentyl)diimidazole C NMR spectrum (100 MHz, DMSO-d6):

[0137] 137.31ppm, 131.24ppm, 119.17ppm, 47.41ppm, 30.41ppm, 23.56ppm.

[0138] (3) Synthesis of the ionic liquid monomer CBIMP of bisimidazole coumarin

[0139] 4 mmol of 7-(4-bromobutoxy)-4-methylcoumarin, 2 mmol of 1,1′-(1,5-pentyl)diimidazole, and 40 ml of acetonitrile were added to a 250 ml four-necked flask. The mixture was refluxed and stirred at 81 °C for 24 h. The solvent was removed by rotary evaporation, and the product was recrystallized to obtain the diimidazole coumarin ionic liquid monomer CBIMP, the structural formula of which is as follows:

[0140]

[0141] 1H NMR spectra (400 MHz, DMSO-d6) of the diimidazole coumarin ionic liquid monomer CBIMP: 8.92 ppm (s, 2H), 7.86 ppm (d, 2H), 7.67 ppm (d, 2H), 7.43 ppm (d, 2H), 6.84 ppm (d, 2H), 6.76 ppm (q, 2H), 6.08 ppm (q, 2H), 4.76 ppm (t, 4H), 4.10 ppm (t, 4H), 4.04 ppm (t, 4H), 2.46 ppm (d, 6H), 2.18 ppm (m, 4H), 1.90 ppm (m, 4H), 1.73 ppm (m, 4H), 1.42 ppm (m, 2H).

[0142] C1NMR spectra (100MHz, DMSO-d6) of the diimidazole coumarin ionic liquid monomer at CBIMP: 162.68ppm, 161.57ppm, 154.73ppm, 153.05ppm, 140.69ppm, 127.63ppm, 127.07ppm, 123.89ppm, 114.39ppm, 111.36ppm, 110.39ppm, 102.78ppm, 68.11ppm, 56.25ppm, 49.91ppm, 30.33ppm, 27.94ppm, 26.76ppm, 23.49ppm, 20.10ppm.

[0143] (4) Synthesis of polyionic liquid P[CBIMP][PF6]

[0144] Dissolve 0.5 g of CBIMP in 4 ml of methanol. After irradiating the solution with ultraviolet light for 12 h, add a methanol solution containing 1.4 mmol of potassium hexafluorophosphate. After thorough stirring, remove the supernatant and wash the product with water until no bromide ions are present in the washing solution (tested with silver nitrate). After drying, the polyionic liquid P[CBIMP][PF6] is obtained, with the following structure:

[0145]

[0146] Example 7

[0147] (1) Synthesis of 7-(6-bromohexyloxy)coumarin

[0148] 100 mL of acetonitrile was added to a 250 mL four-necked flask, followed by 24 mmol of 1,6-dibromohexane, 25 mmol of anhydrous K₂CO₃, and 24 mmol of 7-hydroxycoumarin. The mixture was refluxed at 81 °C with stirring for 8 h (the reaction was monitored by thin-layer chromatography). Stirring was stopped, and the mixture was cooled to room temperature. The mixture was filtered, and the filtrate was evaporated by rotary evaporation. Recrystallization yielded 7-(3-bromopropoxy)-4-methylcoumarin, with the following structural formula:

[0149]

[0150] 1H NMR spectrum of 7-(6-bromohexyloxy)coumarin (400MHz, DMSO-d6)

[0151] 7.81ppm (d, 1H), 7.45ppm (d, 1H), 6.83ppm (q, 1H), 6.80ppm (d, 1H), 6.28ppm (d, 1H), 4.00pp m(t,2H), 3.43ppm(t,2H), 1.84ppm(m,2H), 1.75ppm(m,2H), 1.51ppm(m,2H), 1.49ppm(m,2H)

[0152] Carbon NMR spectrum of 7-(6-bromohexyloxy)coumarin (100 MHz, DMSO-d6)

[0153] 161.71ppm, 161.15ppm, 155.83ppm, 143.37ppm, 128.88ppm, 113.29ppm, 113.13ppm, 11 1.85ppm, 102.68ppm, 69.07ppm, 33.93ppm, 32.92ppm, 29.41ppm, 28.03ppm, 25.39ppm.

[0154] (2) Same as Example 1(2)

[0155] (3) Synthesis of the ionic liquid monomer C2HIMB of diimidazole coumarin

[0156] 4 mmol of 7-(6-bromohexoxy)coumarin, 2 mmol of 1,1′-(1,4-butyl)diimidazole, and 40 ml of acetonitrile were added to a 250 ml four-necked flask. The mixture was refluxed and stirred at 81 °C for 24 h. The solvent was removed by rotary evaporation, and the product was recrystallized to obtain the ionic liquid monomer C2HIMB of diimidazole coumarin, whose structural formula is as follows:

[0157]

[0158] 1H NMR spectrum (400 MHz, DMSO-d6) of the diimidazole coumarin ionic liquid monomer C2HIMB: 8.94 ppm (s, 2H), 7.86 ppm (d, 2H), 7.81 ppm (d, 2H), 7.67 ppm (d, 2H), 7.44 ppm (d, 2H), 6.81 ppm (q, 2H), 6.80 ppm (d, 2H), 6.28 ppm (t, 4H), 4.91 ppm (t, 4H), 4.06 ppm (t, 4H), 4.00 ppm (d, 6H), 2.09 ppm (m, 4H), 1.75 ppm (m, 4H), 1.74 ppm (m, 4H), 1.52 ppm (m, 4H), 1.50 ppm (m, 4H)

[0159] The carbon NMR spectra (100 MHz, DMSO-d6) of the diimidazole coumarin ionic liquid monomer C2HIMB are as follows: 161.71 ppm, 161.15 ppm, 155.83 ppm, 143.37 ppm, 140.93 ppm, 128.88 ppm, 127.08 ppm, 123.97 ppm, 113.29 ppm, 113.13 ppm, 111.85 ppm, 102.68 ppm, 69.07 ppm, 56.00 ppm, 49.41 ppm, 30.73 ppm, 29.40 ppm, 28.05 ppm, 26.13 ppm, and 25.95 ppm.

[0160] (4) Synthesis of polyionic liquid P[C2HIMB][TFSI]

[0161] Dissolve 0.51 g of C2HIMB in 4 ml of methanol. After irradiating the solution with ultraviolet light for 16 h, add a methanol solution containing 1.4 mmol of lithium bis(trifluoromethanesulfonyl)imide. Stir thoroughly, remove the supernatant, and wash the product with water until no bromide ions are present in the washings (tested with silver nitrate). After drying, the polyionic liquid P[C2HIMB][TFSI] is obtained, with the following structure:

[0162]

Claims

1. A photocrosslinked polyionic liquid and its preparation method, characterized in that: Includes the following steps: (1) Synthesis of halogenated compounds containing coumarin units Using hydroxyl-containing coumarin compounds and dihalogenated compounds as raw materials, and organic or inorganic bases as alkalis, the reaction is carried out in an organic solvent under reflux at 50-100℃ for 2-12 hours to prepare halogenated compounds CX containing coumarin units. (2) Synthesis of diimidazole compounds The diimidazole compound MRM was prepared by reacting imidazole sodium salt with a dihalogenated product for 1-3 hours. (3) Synthesis of coumarin-containing diimidazole ionic liquid monomers The halogenated compound CX obtained in step (1) and the diimidazole compound MBM obtained in step (2) were refluxed in an organic solvent at 50-100℃ for 8-36h to obtain the diimidazole ionic liquid monomer CMRMC containing coumarin units. (4) Synthesis of polyionic liquids The compound CMRMC in step (3) was dissolved in a solvent and irradiated with light at 310-370 nm for 4-30 h. Polyionic liquids with different anions were prepared by ion exchange. The general structural formula of photocrosslinked polyionic liquids is as follows: Where A = C3H6, C4H8, C5H 10 C6H 12 C2H4OC2H4, C2H4OC2H4OC2H4, a type of CH2(C6H4)CH2; B = C3H6, C4H8, C s H 10 C6H 12 , C2H4OC2H4, C2H4OC2H4OC2H4, one of CH2(C6H4)CH2; R=H, one of CH3; X=one of bis(trifluoromethanesulfonyl)imide, hexafluorophosphate, tetrafluoroborate, dicyandiamide, bromide, or chloride; n=10-100.

2. The photocrosslinked polyionic liquid and its preparation method according to claim 1, characterized in that: In step (1), the hydroxyl-containing coumarin compound is one of 7-hydroxycoumarin, 6-hydroxycoumarin, 6-hydroxy-4-methylcoumarin, and 7-hydroxy-4-methylcoumarin; the dihalogenated compound is one of 1,3-dibromopropane, 1,4-dibromobutane, 1,5-dibromopentane, 1,6-dibromohexane, 1-bromo-2-(2-bromoethoxy)ethane, 1,2-bis(2-bromoethoxy)ethane, p-dibromobenzyl, 1,3-dichloropropane, 1,4-dichlorobutane, 1,5-dichloropentane, 1,6-dichlorohexane, 1-chloro-2-(2-chloroethoxy)ethane, 1,2-bis(2-chloroethoxy)ethane, and p-dichlorobenzyl.

3. The photocrosslinked polyionic liquid and its preparation method according to claim 1, characterized in that: In step (1), the organic base is triethylamine, piperidine, or pyridine; the inorganic base is anhydrous potassium carbonate or anhydrous sodium carbonate; and the organic solvent is one of 1,4-dioxane, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, or tetrahydrofuran.

4. The photocrosslinked polyionic liquid and its preparation method according to claim 1, characterized in that: In step (1), the molar ratio of the hydroxyl-containing coumarin compound to the dihalogenated product is (1-1.2):1; the molar ratio of the hydroxyl-containing coumarin compound to the alkali agent is 1:(0.8-1.1).

5. The photocrosslinked polyionic liquid and its preparation method according to claim 1, characterized in that: In step (2), the dihalogenated compound is one of 1,3-dibromopropane, 1,4-dibromobutane, 1,5-dibromopentane, 1,6-dibromohexane, 1-bromo-2-(2-bromoethoxy)ethane, 1,2-bis(2-bromoethoxy)ethane, p-dibromobenzyl, 1,3-dichloropropane, 1,4-dichlorobutane, 1,5-dichloropentane, 1,6-dichlorohexane, 1-chloro-2-(2-chloroethoxy)ethane, 1,2-bis(2-chloroethoxy)ethane, and p-dichlorobenzyl.

6. The photocrosslinked polyionic liquid and its preparation method according to claim 1, characterized in that: In step (2), the molar ratio of imidazole sodium salt or potassium salt to dihalogenated product is (2-2.3):

1.

7. The photocrosslinked polyionic liquid and its preparation method according to claim 1, characterized in that: In step (3), the molar ratio of the halogenated compound CX to the diimidazole compound MRM is 2:(0.8-1.0).

8. The photocrosslinked polyionic liquid and its preparation method according to claim 1, characterized in that: In step (4), the solvent is one or two of methanol, ethanol, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, and dichloromethane.

9. The photocrosslinked polyionic liquid and its preparation method according to claim 1, characterized in that: In step (4), the anion is one of bis(trifluoromethanesulfonyl)imide, hexafluorophosphate, tetrafluoroborate, dicyandiamide, bromide, or chloride.

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