Styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator sensitive to LED

Abstract

The present application relates to the field of macromolecular compounds connected to the polymer of styrene or alkyl-substituted styrene, in particular to a LED-sensitive ketoxime ester type water-soluble photoinitiator based on styryl pyridine salt and its manufacturing method and application. The LED-sensitive ketoxime ester type water-soluble photoinitiator based on styryl pyridine salt is characterized in that: a styryl group is connected to a pyridine ring to form a diaryl ethylene structure, and a ketoxime ester is connected to the para position of the double bond on the benzene ring. The manufacturing method of the LED-sensitive ketoxime ester type water-soluble photoinitiator based on styryl pyridine salt is characterized in that: the reaction is carried out according to the reaction formula (a), (b), (c) and (d) in sequence. The present application has good light absorption performance and good matching with LED light source.

Description

[0001] Its manufacturing methods and applications Technical Field

[0002] This invention relates to the field of polymers attached to styrene or alkyl-substituted styrene polymers, specifically to an LED-sensitive styrene-based ketoxime ester-type water-soluble photoinitiator, its manufacturing method, and its application. Background Technology

[0003] Photoinitiator compounds are an important class of fine organic chemical materials. In the field of radiation curing technology using ultraviolet or visible (UV) light or LED (Light-Emitting Diode) as the light source, photoinitiator compounds that can generate free radical active species under light irradiation are key species for inducing efficient photopolymerization reactions in olefin-containing unsaturated systems, and are therefore an important component of radiation curing formulations. Photocuring has many advantages, such as energy saving, environmental protection, high efficiency, speed, and time-space controllability, and has been widely used in traditional fields such as coatings, inks, and adhesives, as well as in high-tech products such as 3D printing. However, traditional photocuring still has some shortcomings, especially the need to add reactive diluents and small amounts of volatile organic solvents to the system, which often harm human health and pollute the environment. Water-soluble photoinitiators can use water instead of reactive diluents during use, making them safer and more environmentally friendly, especially with potential biological applications such as hydrogels and drug carriers.

[0004] The most commonly used water-soluble form on the market is I2959, whose structural formula is shown in structural formula (A):

[0005] --(First)

[0006] However, I2959 has poor water solubility and low absorption within the LED light source wavelength range. Compared to traditional UV curing, LED photocuring using LEDs as the light source has significant advantages such as high energy efficiency, low thermal effect, and no ozone generation. Therefore, developing a series of LED-initiable water-soluble photoinitiators through rational molecular design has great application potential. Summary of the Invention

[0007] In order to overcome the shortcomings of the prior art and provide a polymer with good light absorption performance and good matching with LED light source, this invention discloses an LED-sensitive ketoxime ester-type water-soluble photoinitiator based on styrylpyridinium salt, its manufacturing method and application.

[0008] The present invention achieves its objective through the following technical solution:

[0009] A water-soluble photoinitiator based on a styrylpyridinium salt ketoxime ester, characterized in that: a styrene group is linked to a pyridine ring to form a diarylethylene structure, and the ketoxime ester is attached to the para position of the double bond on the benzene ring, thereby forming an initiator structure with a diarylethylene conjugated structure, the specific molecular structure of which is shown in general formula (i):

[0010] ——(i)

[0011] In general formula (I):

[0012] a. R1 and R2 are each selected arbitrarily from a.1 to a.8 below:

[0013] a.1 Straight-chain or branched alkyl groups containing 1 to 20 carbon atoms,

[0014] a.2 C3~C 12 cycloalkyl,

[0015] a.3 Cycloalkylalkyl,

[0016] a.4 Cycloalkylalkyl groups,

[0017] a.5 C6~C 12 Substituents, including aryl, hydrogen, halogen atoms, R, OR, SR, SOR, SO2R, NRR', CH2OH, CH2OR, CH2OCOR, CH2SR, CH2SCOR, and CH2NRR',

[0018] a.6 Alkyl substituents; said substituents include aryl, hydrogen, halogen atoms, R, OR, SR, SOR, SO2R, NRR', CH2OH, CH2OR, CH2OCOR, CH2SR, CH2SCOR, and CH2NRR'.

[0019] In a.5 and a.6, R and R' are each chosen arbitrarily from a.7 and a.8 below:

[0020] a.7 C1~C 24 Straight-chain or branched alkyl groups

[0021] a.8 C6~C 24 Aryl;

[0022] b. R3 can be any one of the following: b.1 to b.5

[0023] b.1 Straight-chain alkyl or branched alkyl groups containing 1 to 10 carbon atoms

[0024] b.2 C3~C 12 cycloalkyl,

[0025] b.3 Cycloalkylalkyl,

[0026] b.4 C6~C 12 Aryl,

[0027] b.5 Alkyl aryl;

[0028] c. X - The corresponding anion;

[0029] Photoinitiators themselves and the radiation curing systems in which they participate have a certain inhibitory effect on some types of bacteria.

[0030] The LED-sensitive ketoxime ester-type water-soluble photoinitiator based on styrylpyridinium salt is characterized by:

[0031] X - X is a variety of highly water-soluble anions. - Choose any one from c.1 to c.9 below:

[0032] c.1 I - ,

[0033] c.2 CF3SO3 - ,

[0034] c.3 Br - ,

[0035] c.4 C7H7SO3 - ,

[0036] c.5 CH3COO - ,

[0037] c.6 CF3COO - ,

[0038] c.7 ,

[0039] c.8 ,

[0040] c.9 ;

[0041] R includes at least one of the following structures: d.1 and d.2

[0042] d.1 Replacing hydrogen atoms with fluorine atoms to form a fluorocarbon chain structure.

[0043] d.2 Contains 1 to 6 discontinuous oxygen, nitrogen, or sulfur elements.

[0044] The LED-sensitive ketoxime ester-type water-soluble photoinitiator based on styrylpyridinium salt is characterized in that: when R and R' are present simultaneously, a 3- to 6-membered ring structure is formed, which substitutes various substituted aryl groups.

[0045] The method for manufacturing the LED-sensitive styrene-based ketoxime ester type water-soluble photoinitiator is characterized by the following steps being carried out sequentially:

[0046] I. + ——(a),

[0047] According to reaction formula (a), 4-vinylpyridine and 4'-bromobenzophenone with different R1 substituents were reacted with potassium carbonate in the presence of bis(triphenylphosphine)palladium dichloride as a catalyst. The solvent used in the reaction was DMF, the reaction temperature was 100℃~110℃, and the reaction time was 6 hours~12 hours. Intermediate a was purified by column chromatography or recrystallization. The molecular structure of intermediate a is shown in general formula (ii).

[0048] —(ii);

[0049] II. —(b),

[0050] According to reaction formula (b), intermediate a generated in step I was reacted with isoamyl nitrite in the presence of concentrated hydrochloric acid to prepare intermediate b with a ketoxime structure. The solvent used in the reaction was tetrahydrofuran, the reaction temperature was 0℃, and the reaction time was 12 hours to 36 hours. After extraction and vacuum distillation to remove the organic solvent, intermediate b was obtained. It can be used directly in the next reaction without further purification. The molecular structure of intermediate b is shown in general formula (iii).

[0051] —(iii);

[0052] III. —(c),

[0053] According to reaction formula (c), intermediate b generated in step II is reacted with acid anhydride or the corresponding acyl chloride in the presence of triethylamine to prepare intermediate c with a ketoxime ester or oxime ester structure. The solvent used in the reaction is dichloromethane, the reaction temperature is 0℃, and the reaction time is 12 hours to 36 hours. Intermediate c is purified by column chromatography or recrystallization. The molecular structure of intermediate c is shown in general formula (iv).

[0054] —(iv);

[0055] IV. ——(d),

[0056] According to reaction formula (d), the intermediate c generated in step III is reacted directly with R3-X to generate a salt solution. The solvent used in the reaction is DMF, the reaction temperature is 40℃~90℃, and the reaction time is 12 hours~36 hours. The salt solution generated in the reaction is added to diethyl ether to obtain a precipitate. The precipitate is filtered and dried to obtain the final product, which is the water-soluble photoinitiator. The molecular structure of the final product is shown in general formula (i).

[0057] The method for manufacturing the LED-sensitive styrene-based ketoxime ester type water-soluble photoinitiator is characterized by:

[0058] In step IV:

[0059] X - Choose any one from c.1 to c.9 below:

[0060] c.1 I - ,

[0061] c.2 CF3SO3 - ,

[0062] c.3 Br - ,

[0063] c.4 C7H7SO3 - ,

[0064] c.5 CH3COO - ,

[0065] c.6 CF3COO - ,

[0066] c.7 ,

[0067] c.8 ,

[0068] c.9 ,

[0069] X - When selecting the structure c.5 to c.9, first prepare pyridine iodide salt, dissolve it in water, add an equimolar amount of silver salt to the solution, stir at room temperature for 1 h to 12 h, filter and collect the filtrate, remove the solvent by vacuum distillation, wash the obtained solid with diethyl ether, filter and dry to obtain the target structure;

[0070] R3-X can be any one of methyl p-toluenesulfonate, ethyl p-toluenesulfonate, methyl trifluoromethanesulfonate, iodomethane, iodoethane, and iodopropane.

[0071] When R3-X is selected from methyl p-toluenesulfonate, the solvent used is ethyl acetate; when R3-X is selected from methyl trifluoromethanesulfonate, iodomethane, iodoethane, and iodopropane, the solvent used is diethyl ether.

[0072] The application of the LED-sensitive styrene-based ketoxime ester-type water-soluble photoinitiator is characterized by the following steps being carried out sequentially:

[0073] S1. Ingredients:

[0074] The mass fractions of monomer, water-soluble photoinitiator, and additives are as follows:

[0075] Monomer: 100

[0076] Water-soluble photoinitiator: 1–1.5,

[0077] Additives: 0-4.5;

[0078] S2. Stirring:

[0079] The monomer, water-soluble photoinitiator, and additives are mixed and stirred until they are fully dissolved to form a polymer.

[0080] S3. Irradiation:

[0081] The polymer is irradiated with light sources of different wavelengths or different intensities. The light sources are any one of mercury lamps, LEDs with an emission wavelength of 313nm to 425nm, and LDIs with an emission wavelength of 313nm to 425nm.

[0082] S4. The polymerization conversion rate was studied by analyzing the changes in the characteristic peaks of the polymer obtained in S3 using online infrared spectroscopy.

[0083] The polymer also contains inorganic or organic fillers and / or colorants (such as pigments or dyes) added as needed, as well as other additives (such as UV absorbers, light stabilizers, flame retardants, leveling agents or defoamers) and solvents, etc.

[0084] Water-soluble monomers are polymerizable monomers containing olefin bonds, including but not limited to: (meth)acrylamide monomer, (meth)acrylic acid, sodium (meth)acrylate, potassium (meth)acrylate, N-vinylpyrrolidone, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, sodium 2-acrylamide-2-methylpropanesulfonate, etc.

[0085] The application of the LED-sensitive styrene-based ketoxime ester-type water-soluble photoinitiator is characterized by:

[0086] A water-soluble photoinitiator and a water-soluble monomer are dissolved in water to form a solution. The solution is then irradiated with a light source such as an LED with a wavelength of 365 nm to 425 nm. The polymerization or cross-linking of the water-soluble monomer is achieved by the absorption of single photons by the solution, thereby preparing an antibacterial hydrogel system or an aqueous coating.

[0087] The application of the LED-sensitive styrene-based ketoxime ester-type water-soluble photoinitiator is characterized by:

[0088] A mixture for manufacturing a light (ultraviolet or visible light or LED light or equivalent light source) radiation-cured mixture, the formulation of which is as follows:

[0089] Component I: Contains at least one water-soluble photoinitiator described by general formula (i), and

[0090] Component II: Contains at least one compound with an olefinic bond (C=C) that is capable of free radical polymerization;

[0091] With a total mass of 100 parts for the mixture, the mass fraction of component I is 0.01 to 30.

[0092] Compounds containing olefin bonds that can be free radically polymerized include, but are not limited to: (meth)acrylamide functionalized (meth)acrylic acid copolymers, polyurethane formate (meth)acrylates, polyester (meth)acrylates, unsaturated polyesters, polyether (meth)acrylates, siloxane (meth)acrylates, epoxy resin (meth)acrylates, polyethylene glycol diacrylates, and similar water-soluble or water-dispersible compounds of the above substances.

[0093] The application of the LED-sensitive styrene-based ketoxime ester-type water-soluble photoinitiator is characterized by:

[0094] The mass fraction of component I is 0.5–10;

[0095] Component II is selected from compounds or mixtures that are cross-linked by olefinic free radical polymerization; Component II is selected from monomers, oligomers or prepolymers, or aqueous dispersions of said monomers, oligomers or prepolymers, or mixtures or copolymers of at least two of said monomers, oligomers and prepolymers.

[0096] Examples of compounds conforming to general formula (i) are shown below, as shown in general formulas (i-1) to (i-18):

[0097] —(i-1),

[0098] —(i-2),

[0099] —(i-3),

[0100] —(i-4),

[0101] —(i-5),

[0102] —(i-6),

[0103] —(i-7),

[0104] —(i-8),

[0105] —(i-9),

[0106] —(i-10),

[0107] —(i-11),

[0108] —(i-12),

[0109] —(i-13),

[0110] —(i-14),

[0111] —(i-15),

[0112] —(i-16),

[0113] —(i-17),

[0114] ——(i-18).

[0115] Ketooxime esters with stilbene-like structures exhibit excellent light absorption in the near-ultraviolet and visible light regions, and also possess superior thermal stability, making them a class of free radical photoinitiators with significant potential applications. Furthermore, positively charged compounds, such as those with quaternary ammonium salts, quaternary phosphonium salts, guanidine salts, and pyridinium salts, have been shown to be electrostatically attracted to bacteria, thereby interfering with their normal physiological activities and killing them, thus achieving a bacteriostatic effect.

[0116] To address the aforementioned technical challenges, a class of styrene-pyridinium salt-derived ketoxime ester-type water-soluble photoinitiators has been invented. In the field of photopolymerization, water-soluble photoinitiators with high photosensitivity, high stability, ease of preparation, and antibacterial properties are essential. Furthermore, the synthesis steps for such initiators should be simple, low-cost, environmentally friendly, and produce minimal waste. With increasing awareness of environmental protection, production safety, and occupational health requirements, as well as the continuous development of photopolymerization technology, low-energy-consumption, high-safety, and environmentally friendly exposure lamp sources such as LEDs and LDIs have become a trend in the application and development of this technology.

[0117] This invention relates to the field of new materials and organic chemicals, and particularly to a class of LED-sensitive ketoxime ester-type water-soluble photoinitiators based on styrylpyridinium salts. These photoinitiators have the structure shown in general formula (I), where the styrene group and pyridine ring form a diarylethylene structure. The oxime ester is attached to the para position of the double bond on the benzene ring, thus forming an initiator structure with a certain conjugated structure. The corresponding X- can be p-toluenesulfonate, trifluoromethanesulfonate, iodide ions, etc. This series of photoinitiators exhibits strong light absorption in the near-ultraviolet-visible region and high photolysis efficiency. The pyridinium salts with different anions not only provide water solubility but also provide certain antibacterial effects. Their chemical preparation process, their use as radiation-curing photoinitiators, and their applications in radiation-cured formulations, especially UV-Vis-LED excitable photocurable water-based coatings or inks, 3D printing, antibacterial hydrogels, and many other applications are extensive. Attached Figure Description

[0118] Figure 1 This is the 1H NMR spectrum of the i-3 structure molecule in DMSO-d6 in this invention.

[0119] Figure 2 This is the 1H NMR spectrum of the i-5 structure molecule in DMSO-d6 in this invention.

[0120] Figure 3 These are the UV-Vis absorption spectra of molecules with i-3 and i-5 structures in this invention in water.

[0121] Figure 4 This is a kinetic curve of the thick-film free radical polymerization rate initiated by the molecules of the i-3 and i-5 structures in this invention under the excitation of a 365nm LED light source.

[0122] Figure 5 This is a kinetic curve of the thick-film free radical polymerization rate initiated by the molecules of the i-3 and i-5 structures in this invention under the excitation of a 385nm LED light source.

[0123] Figure 6This is a kinetic curve of the thick film free radical polymerization rate initiated by the molecules of the i-3 and i-5 structures in this invention under the excitation of a 405nm LED light source. Detailed Implementation

[0124] The present invention will be further illustrated below through specific embodiments.

[0125] Example 1

[0126] Preparation of water-soluble photoinitiators of the ketoxime ester type as shown in general formula (i-3):

[0127] ——(i-3).

[0128] I. + —(i-3-i),

[0129] Following reaction formula (i-3-i), 47.56 mmol of 4-vinylpyridine, 47.56 mmol of 4'-bromophenylpentanone, 71.34 mmol of potassium carbonate, and 60 mL of DMF were added sequentially to a dry three-necked flask. Under a nitrogen atmosphere, 0.47 mmol of bis(triphenylphosphine)palladium dichloride catalyst was added, and the mixture was heated in an oil bath at 100 °C. After 6 hours, the starting material disappeared as monitored by TCL. The DMF was concentrated under reduced pressure, and the reaction solution was poured into 100 mL of deionized water. The precipitate was filtered, dried, and purified by column chromatography to give a pale yellow solid styrylpyridine compound, i.e., intermediate i-3-a, with a yield of 90.31%. The molecular structure of intermediate i-3-a is shown in the general formula (i-3-aa).

[0130] ——(i-3-aa).

[0131] II. ——(i-3-ii),

[0132] Following reaction formula (i-3-ii), 40 mmol of intermediate i-3-a obtained in step I was added to 60 mL of tetrahydrofuran solution in a dry three-necked flask. The mixture was stirred in an ice bath at 0 °C. Then, 200 mmol of 38% concentrated hydrochloric acid and 60 mmol of isoamyl nitrite were added dropwise, and the mixture was stirred at room temperature. After 12 hours, the starting material disappeared as monitored by TCL. The reaction solution was poured into 50 mL of water, and the organic layer was extracted with dichloromethane. After drying, the mixture was distilled under reduced pressure to obtain a yellow solid oxime compound, i.e., intermediate i-3-b, with a yield of 90.01%. The molecular structure of intermediate i-3-b is shown in the general formula (i-3-ba).

[0133] ——(i-3-ba).

[0134] III. —(i-3-iii),

[0135] Following reaction formula (i-3-iii), in a dry three-necked flask, 35 mmol of intermediate i-3-b obtained in step II and 175 mmol of anhydrous triethylamine were added to 60 mL of anhydrous dichloromethane. The mixture was cooled to 0°C in an ice bath under nitrogen protection. 87.5 mmol of acetic anhydride was added dropwise, and the reaction was continued at 0°C for another half hour, then allowed to proceed to room temperature. After 12 hours, the starting material disappeared as monitored by TCL. The reaction solution was poured into 50 mL of water, and the organic phase was extracted with dichloromethane. After drying, the solution was distilled under reduced pressure and purified by column chromatography. The product was a pale yellow solid ketoxime ester compound, i.e., intermediate i-3-c, with a yield of 85.10%. The molecular structure of intermediate i-3-c is shown in the general formula (i-3-ca).

[0136] ——(i-3-ca).

[0137] IV. —(i-3-iv),

[0138] Following reaction formula (i-3-iv), 10 mmol of the intermediate i-3-c obtained in step III and 40 mmol of methyl p-toluenesulfonate were added to 20 mL of DMF solution in a dry single-necked flask. The mixture was stirred in a 60 °C oil bath under nitrogen protection. After 12 hours, the starting material disappeared as monitored by TCL. After cooling to room temperature, ethyl acetate was added to the reaction solution until a precipitate formed. The precipitate was filtered off and dried. The product was a pale yellow solid, a water-soluble ketoxime ester photoinitiator, i.e., the target product as shown in general formula (i-3), with a yield of 98.05%.

[0139] HR-MS (C 21 H 23 N2O3 + ):

[0140] Theoretical: m / z: 351.1704; Experimental: 351.1710.

[0141] NMR of the target product represented by general formula (i-3): ¹H NMR (400 MHz, DMSO-d⁶) δ 8.92 (d, J = 6.5 Hz, 2H), 8.28 (d, J = 6.4 Hz, 2H), 8.14 – 8.04 (m, 3H), 7.92 (d, J = 8.3 Hz, 2H), 7.72 (d, J = 16.4 Hz, 1H), 7.48 (d, J = 7.8 Hz, 2H), 7.11 (d, J = 7.8 Hz, 2H), 4.28 (s, 3H), 2.81 – 2.68 (m, 2H), 2.28 (s, 3H), 2.26 (s, 3H), 1.57 (p, J = 7.4 Hz, 2H). Hz, 2H), 0.95 (t, J = 7.4 Hz, 3H).

[0142] For specific NMR spectra, see Figure 1 .

[0143] Example 2

[0144] Preparation of water-soluble photoinitiators of the ketoxime ester type as shown in general formula (i-5):

[0145] ——(i-5).

[0146] Steps I through III are the same as in Example 1.

[0147] IV. ——(i-5-iv)

[0148] Following reaction formula (i-5-iv), 10 mmol of the intermediate i-3-c obtained in step III and 40 mmol of iodomethane were added to 20 mL of DMF solution in a dry single-necked flask. The mixture was stirred in a 60 °C oil bath under nitrogen protection. After 12 hours, the starting material disappeared as monitored by TCL. After cooling to room temperature, diethyl ether was added to the reaction solution until a precipitate formed. The precipitate was filtered off and dried. The product was a pale yellow solid ketoxime ester-type water-soluble photoinitiator, i.e., the target product as shown in general formula (i-5).

[0149] HR-MS (C 21 H 23 IN2O3):

[0150] Theoretical: m / z: 351.1704; Experimental: 351.1714.

[0151] NMR of the target product represented by general formula (i-5): 1H NMR (400 MHz, DMSO-d6) δ 8.93 (d, J = 6.4 Hz, 2H), 8.29 (d, J = 6.7 Hz, 2H), 8.21 – 8.02 (m, 3H), 7.93 (d, J = 8.2 Hz, 2H), 7.73 (d, J = 16.4 Hz, 1H), 4.29 (s, 3H), 2.80 – 2.68 (m, 2H), 2.26 (s, 3H), 1.58 (h, J = 7.6 Hz, 2H), 0.94 (t, J = 7.4 Hz, 3H).

[0152] For specific NMR spectra, see Figure 2 .

[0153] Example 3

[0154] Preparation of water-soluble photoinitiators of the ketoxime ester type as shown in general formula (i-6):

[0155] ——(i-6).

[0156] Steps I and II are the same as in Example 1.

[0157] III. —(i-6-iii),

[0158] Following reaction formula (i-6-iii), in a dry three-necked flask, 35 mmol of intermediate i-3-b obtained in step II and 175 mmol of anhydrous triethylamine were added to 60 mL of anhydrous dichloromethane. The mixture was cooled to 0°C in an ice bath under nitrogen protection. 87.5 mmol of p-methylbenzoyl chloride was added dropwise, and the reaction was continued at 0°C for another half hour, then allowed to proceed to room temperature. After 12 hours, the starting material disappeared as monitored by TCL. The reaction solution was poured into 50 mL of water, and the organic phase was extracted with dichloromethane. After drying, the solution was distilled under reduced pressure and purified by column chromatography. The product was a pale yellow solid ketoxime ester compound, i.e., intermediate i-3-c, with a yield of 85.10%. The molecular structure of intermediate i-6-c is shown in the general formula (i-6-ca).

[0159] ——(i-6-ca).

[0160] IV. —(i-6-iv),

[0161] Following reaction formula (i-6-iv), 10 mmol of the intermediate i-3-c obtained in step III and 40 mmol of iodomethane were added to 20 mL of DMF solution in a dry single-necked flask. The mixture was stirred in a 60 °C oil bath under nitrogen protection. After 12 hours, the starting material disappeared as monitored by TCL. After cooling to room temperature, ethyl acetate was added to the reaction solution until a precipitate formed. The precipitate was filtered off and dried. The product was a pale yellow solid, a water-soluble ketoxime ester photoinitiator, i.e., the target product as shown in general formula (i-6).

[0162] HR-MS (C 27 H 27 IN2O3):

[0163] Theoretical: m / z: 427.2017; Experimental: 427.2021.

[0164] Example 4

[0165] The UV-Vis absorption spectra and related photophysical parameters of the two target products, namely the one prepared by general formula (i-3) in Example 1 and the one prepared by general formula (i-5) in Example 2, were tested.

[0166] Accurately weigh a certain amount of the target products obtained in Examples 1 and 2, and the sample from the comparative example, dissolve them in a volumetric flask using water as the solvent, and then measure the UV-Vis absorption spectrum. The specific curves are shown in the figure below. Figure 3 As shown in Table 1, the maximum absorption wavelength, the molar extinction coefficient at the maximum absorption wavelength, and the molar extinction coefficients at 365 nm, 385 nm, and 405 nm are all present.

[0167] Table 1: Light absorption properties of the two initiators in water in the examples

[0168]

[0169] As can be seen from Table 1, the target products obtained in the two examples have good light absorption performance in the UVA to visible light range, and are expected to be used in the field of photoinitiated polymerization in this band.

[0170] Example 5

[0171] The two target products, represented by general formula (i-3) obtained in Example 1 and general formula (i-5) obtained in Example 2, were subjected to photocuring experiments at LEDs at 365 nm, 385 nm, and 405 nm in an aqueous formulation containing acrylamide monomer:

[0172] Formula 1:

[0173] Monofunctional monomer aqueous solution: 99 parts by mass

[0174] Photoinitiator: 1 part by weight;

[0175] The monofunctional monomer aqueous solution was selected from a solution of acrylamide (AM) and water in a mass ratio of 1:1, and the photoinitiator was selected from the target product of general formula (i-3) obtained in Example 1.

[0176] Formula 2:

[0177] Monofunctional monomer aqueous solution: 99 parts by mass

[0178] Photoinitiator: 1 part by weight;

[0179] The monofunctional monomer aqueous solution was selected from a solution of acrylamide (AM) and water in a mass ratio of 1:1, and the photoinitiator was selected from the target product of general formula (i-5) obtained in Example 2.

[0180] The photopolymer kinetics curves of the two formulation systems under LED light source excitation at 365 nm, 385 nm, and 405 nm were tested using FT-IR. The conversion rate of acrylamide was calculated based on the change in the area of ​​the in-plane bending vibration peak of the olefin CH at 1280 cm⁻¹. The specific curves are shown in Figure 1. Figure 4 , Figure 5 and Figure 6 As shown.

[0181] Example 6

[0182] The minimum inhibitory concentration (MIC) of the two target products, as shown in general formula (i-3) obtained in Example 1 and general formula (i-5) obtained in Example 2, was tested.

[0183] The micro-broth dilution method was used for determination. First, an appropriate amount of LB broth (autoclaved) was added to a 96-well plate. Then, 2 mg / mL of the target product dissolved in water was added to the first well of each row of the 96-well plate. The plate was diluted using a two-fold dilution method. Finally, an equal volume of bacterial suspension was inoculated into each well, resulting in final drug concentrations of 500 μg / mL, 250 μg / mL, 125 μg / mL, 62.5 μg / mL, 31.25 μg / mL, 16 μg / mL, 8 μg / mL, 4 μg / mL, 2 μg / mL, and 1 μg / mL for each test group. Two parallel blank control groups (i.e., no sample added) were also included in the test. The samples were incubated at 37°C for 8 hours. The bacterial growth was assessed by observing changes in the absorbance (OD) value of the test solution, and the MIC value of the sample was recorded. In this embodiment, the concentration corresponding to an OD value increase of half that of the blank control group was used as the MIC value of the drug. The MIC values ​​of the two target products against Escherichia coli and Staphylococcus aureus are shown in Table 2:

[0184] Table 2: MIC values ​​of the two target products against Escherichia coli and Staphylococcus aureus

[0185]

[0186] As can be seen from Table 2, the target products obtained in both examples have significant antibacterial effects.

Claims

1. An LED-sensitive, styrylpyridinium-based, ketoxime ester-type water-soluble photoinitiator, characterized in that: The styrene group is attached to the pyridine ring to form a diarylethene structure, and the ketoxime ester is attached to the para position of the double bond on the benzene ring. The molecular structure is shown in general formula (i): ——(i) The specific structure is as follows: ——(i-1)， ——(i-2)， ——(i-3)， ——(i-4)， ——(i-5)， ——(i-6)， ——(i-7)， ——(i-8)， ——(i-9)， ——(i-10)， ——(i-11)， ——(i-12)， ——(i-13)， ——(i-14)， ——(i-15)， ——(i-16)， ——(i-17)， ——(i-18)。 2. The method for preparing an LED-sensitive ketoxime ester-type water-soluble photoinitiator based on styrylpyridinium salt as described in claim 1, characterized in that: Follow these steps in sequence: I. + ——(a), According to reaction formula (a), 4-vinylpyridine and 4'-bromobenzophenone with different R1 substituents were reacted with potassium carbonate in the presence of bis(triphenylphosphine)palladium dichloride as a catalyst. The solvent used in the reaction was DMF, the reaction temperature was 100-110℃, and the reaction time was 6-12 h. Intermediate a was purified by column chromatography or recrystallization. The molecular structure of intermediate a is shown in general formula (ii). ——(ii); II. —(b), According to reaction formula (b), intermediate a generated in step I was reacted with isoamyl nitrite in the presence of concentrated hydrochloric acid to prepare intermediate b with a ketoxime structure. The solvent used in the reaction was tetrahydrofuran, the reaction temperature was 0℃, and the reaction time was 12-36 h. After extraction and vacuum distillation, intermediate b was obtained. The molecular structure of intermediate b is shown in general formula (iii). ——(iii); III. ——(c), According to reaction formula (c), intermediate b generated in step II is reacted with acid anhydride or the corresponding acyl chloride in the presence of triethylamine to prepare intermediate c with a ketoxime ester or oxime ester structure. The solvent used in the reaction is dichloromethane, the reaction temperature is 0℃, and the reaction time is 12-36 h. Intermediate c is purified by column chromatography or recrystallization. The molecular structure of intermediate c is shown in general formula (iv). ——(iv); IV. ——(d), According to reaction formula (d), the intermediate c generated in step III is directly reacted with R3-X to form a salt solution. The solvent used in the reaction is DMF, the reaction temperature is 40-90℃, and the reaction time is 12-36 h. The salt solution generated in the reaction is added to diethyl ether to obtain a precipitate. The precipitate is filtered and dried to obtain the final product, which is the water-soluble photoinitiator. Among them, X... - For I - ,Br - CF3SO3 - or C7H7SO3 - The molecular structure of the final product is shown in general formula (i).

3. The LED-sensitive styrene-based ketoxime ester water-soluble photoinitiator as described in claim 1, used to prepare antibacterial hydrogel systems or aqueous coatings, is characterized in that: A water-soluble photoinitiator and a water-soluble monomer are dissolved in water to form a solution. The solution is then irradiated with an LED light source with a wavelength of 365-425 nm. The polymerization or cross-linking of the water-soluble monomer is achieved by the absorption of single photons by the solution, thereby preparing an antibacterial hydrogel system or an aqueous coating. The water-soluble monomer is selected from one or more of (meth)acrylamide monomer, (meth)acrylic acid, sodium (meth)acrylate, potassium (meth)acrylate, N-vinylpyrrolidone, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and sodium 2-acrylamide-2-methylpropanesulfonate.

4. The LED-sensitive ketoxime ester-type water-soluble photoinitiator based on styrylpyridinium salt as described in claim 1, used to manufacture mixtures that are cured by ultraviolet or visible light, LED light, or equivalent light source radiation, is characterized in that: The formulation of the mixture is as follows: Component I: Contains at least one water-soluble photoinitiator described by general formula (i), and Component II: Contains at least one compound with an olefinic bond (C=C) that is capable of free radical polymerization; The total mass of the mixture is 100 parts, and the mass fraction of component I is 0.01 to 30.

5. The application of the LED-sensitive ketoxime ester-type water-soluble photoinitiator based on styrylpyridinium salt as described in claim 4, characterized in that: The mass fraction of component I is 0.5–10; Component II is selected from compounds or mixtures that are cross-linked by olefinic free radical polymerization; Component II is selected from monomers, oligomers or prepolymers, or aqueous dispersions of said monomers, oligomers or prepolymers, or mixtures or copolymers of at least two of said monomers, oligomers and prepolymers.

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