Radical photopolymerization catalysts based on diphenylcarbazole and methods of making and photo-curing applications thereof

Abstract

The application discloses a kind of radical polymerization photocatalyst based on diphenyl carbazole and preparation method and photocuring application thereof, belong to organic chemistry and polymer material technology.Diphenyl carbazole and other raw materials are generated radical polymerization photocatalyst by nucleophilic substitution reaction, ammonolysis ring-opening reaction, nucleophilic substitution reaction or nucleophilic addition reaction on carbonyl group, the radical polymerization photocatalyst has strong light absorption, can produce long-life high-energy triplet excited state under light, and through excited state electron transfer / energy transfer, catalyze acrylamide, acryloyl morpholine, hydroxyethyl acrylamide, hydroxymethyl acrylamide, dimethyl acrylamide and other double bond monomers based on acrylamide structure decomposition to generate radical, initiate radical polymerization of monomer and prepolymer containing unsaturated double bond.

Description

Technical Field

[0001] This invention belongs to the field of organic chemistry and polymer materials technology, specifically relating to a free radical polymerization photocatalyst based on diphenylcarbazole, its preparation method, and its photocuring application. Background Technology

[0002] In the field of photocuring technology, photoinitiators play a crucial role. This technology primarily relies on the decomposition of photoinitiators under light irradiation to generate free radicals, which then initiate monomer polymerization, thereby achieving material curing. However, existing photocuring technologies face several challenges in practical applications.

[0003] Specifically, to ensure complete curing of the monomer, a relatively large amount of photoinitiator is usually added to the system, often reaching 2-3 wt.% of the total system mass. While a higher concentration of photoinitiator helps improve curing efficiency, it also brings a series of problems.

[0004] First, the large amount of photoinitiator gives the system a strong light absorption capacity. When light shines on the surface of the system, it attenuates rapidly due to the high absorption of the photoinitiator, making it difficult to penetrate into the interior of the system. This results in the monomers inside the system not receiving effective light exposure, thus limiting the depth of curing.

[0005] Secondly, the excessive use of photoinitiators may also lead to some side effects. For example, excessive photoinitiators may accelerate the rate of photochemical reactions, leading to runaway reactions or adverse consequences. In addition, excessive photoinitiators may also cause excessive cross-linking or degradation of photosensitive materials, resulting in a decline in material properties, such as incomplete curing and reduced strength. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a free radical polymerization photocatalyst based on diphenylcarbazole, its preparation method and photocuring application, so as to solve the technical problem of excessive photoinitiator addition during the photocuring process in the prior art.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] The free radical polymerization photocatalyst based on diphenylcarbazole has the following chemical structural formula:

[0009]

[0010] Wherein, R1 or R2 is one of the following: diester group of CH3CH2O-CO-CH-CO-OCH2CH3, diester group of CH3CH2O-CO-C-CO-OCH2CH3, chiral ester group of CH3CH-CO-O-CH3, hydroxyl group of CH2CH2-OH, acrylate group of CH2CH-CO-OCH2CH2, sodium sulfonate group of CH2CH2CH2-SO3Na, or isocyanate group.

[0011] The above-described method for preparing a free radical polymerization photocatalyst based on diphenylcarbazole includes a first type of free radical polymerization photocatalyst and a second type of free radical polymerization photocatalyst; the first type of free radical polymerization photocatalyst is a free radical polymerization photocatalyst with chemical structural formula (I) or chemical structural formula (II); the second type of free radical polymerization photocatalyst is a free radical polymerization photocatalyst with chemical structural formula (I) or chemical structural formula (II).

[0012] The aforementioned free radical polymerization photocatalyst is prepared by diphenylcarbazole and other raw materials through a nucleophilic substitution reaction on saturated carbon or an ammonolytic ring-opening reaction.

[0013] The second type of free radical polymerization photocatalyst is prepared by a first type of free radical polymerization photocatalyst and other raw materials through a nucleophilic substitution reaction or a nucleophilic addition reaction on the carbonyl group;

[0014] The other raw materials carry R1 or R2.

[0015] A further improvement of the present invention is that:

[0016] Preferably, the diphenylcarbazole is 2,7-diphenylcarbazole or 1,6-diphenylcarbazole;

[0017] The 2,7-diphenylcarbazole reacts with other raw materials to generate a type of free radical polymerization photocatalyst with chemical structural formula (I);

[0018] The 1,6-diphenylcarbazole reacts with other raw materials to generate a type of free radical polymerization photocatalyst with chemical structural formula (II);

[0019] The other raw materials are halogenated compounds, ethylene carbonate, or 1,3-propanesulfonate lactone.

[0020] Preferably, when other raw materials are halogenated products, the halogenated product and diphenylcarbazole generate a type of free radical polymerization photocatalyst through a nucleophilic substitution reaction, wherein R1 or R2 in the type of free radical polymerization photocatalyst is a diester group of CH3CH2O-CO-CH-CO-OCH2CH3, a diester group of CH3CH2O-CO-C-CO-OCH2CH3, or a chiral ester group of CH3CH-CO-O-CH3.

[0021] Preferably, the halogenated product is diethyl bromide, diethyl dibromomalonate, methyl (R)-(+)-2-chloropropionate, or methyl (S)-(-)-2-chloropropionate.

[0022] In the free radical polymerization photocatalyst generated by the reaction of diphenylcarbazole and diethyl bromide, R1 or R2 is a diester group of CH3CH2O-CO-CH-CO-OCH2CH3.

[0023] In the free radical polymerization photocatalyst generated by the reaction of diphenylcarbazole and diethyl dibromomalonate, R1 or R2 is a diester group of CH3CH2O-CO-C-CO-OCH2CH3;

[0024] In the free radical polymerization photocatalyst generated by the reaction of diphenylcarbazole and (R)-(+)-2-chloropropionate or (S)-(-)-2-chloropropionate, R1 or R2 is a chiral ester group of CH3CH-CO-O-CH3.

[0025] Preferably, the diphenylcarbazole and ethylene carbonate are reacted via ammonolysis to generate a type of free radical polymerization photocatalyst, wherein R1 or R2 in the type of free radical polymerization photocatalyst is a hydroxyl group of CH2CH2-OH.

[0026] Preferably, a radical polymerization photocatalyst in which R1 or R2 is a hydroxyl group of CH2CH2-OH is used as an intermediate, and the intermediate and acryloyl chloride are reacted by nucleophilic substitution on the carbonyl group to generate a second type of radical polymerization photocatalyst, wherein R1 or R2 on the second type of radical polymerization photocatalyst is an acrylate group of CH2CH-CO-OCH2CH2.

[0027] Preferably, a free radical polymerization photocatalyst in which R1 or R2 is a hydroxyl group of CH2CH2-OH is used as an intermediate, and the intermediate and hexamethylene diisocyanate trimer are reacted by nucleophilic addition to generate a second type of free radical polymerization photocatalyst, wherein R1 or R2 on the second type of free radical polymerization photocatalyst is a triisocyanate group.

[0028] Preferably, the diphenylcarbazole and 1,3-propanesulfonate lactone are converted into a free radical polymerization photocatalyst via an ammonolysis ring-opening reaction, wherein R1 or R2 in the free radical polymerization photocatalyst is a sodium sulfonate group of CH2CH2CH2-SO3Na.

[0029] A photocuring application of the above-mentioned diphenylcarbazole-based free radical polymerization photocatalyst, wherein the free radical polymerization photocatalyst is used to initiate and catalyze the free radical polymerization of acrylamide monomers under ultraviolet or visible light irradiation.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] This invention discloses a diphenylcarbazole-based free radical polymerization photocatalyst, synthesized from diphenylcarbazole groups and other reactants. The diphenylcarbazole compounds in this free radical polymer photocatalyst exhibit strong light absorption, enabling them to generate long-lived, high-energy triplet excited states under light irradiation. Through excited-state electron / energy transfer, they catalyze the decomposition of acrylamide-based double-bonded monomers such as acrylamide, acryloylmorpholine, hydroxyethylacrylamide, hydroxymethylacrylamide, and dimethylacrylamide to generate free radicals, initiating the free radical polymerization of monomers and prepolymers containing unsaturated double bonds. Compared to traditional photoinitiators, the diphenylcarbazole-based organic photocatalyst can continuously catalyze free radical generation under light irradiation and is not decomposed or consumed during polymerization. Therefore, only a small amount needs to be added to achieve efficient curing of photocurable systems containing acrylamide monomers, realizing a highly efficient and continuous photopolymerization process, significantly improving the polymerization rate and product molecular weight. The prepared free radical polymerization photocatalyst exhibits low migration, low odor, and resistance to yellowing. It has significant application value in polymer material preparation, surface coating, 3D printing, and biomedicine. Attached Figure Description

[0032] Figure 1 The UV-Vis absorption spectrum of compound 3 prepared in Example 3;

[0033] Figure 2 The fluorescence emission spectrum of compound 3 prepared in Example 3;

[0034] Figure 3 A photograph of the photocatalytically cured product of compound 3 p-acryloylmorpholine resin prepared in Example 3;

[0035] Figure 4 This is a schematic diagram of the high-depth photocatalytic curing of compound 3 p-acryloylmorpholine resin prepared in Example 3. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings:

[0037] The first aspect of the present invention discloses an organic photocatalyst based on diphenylcarbazole, having a structure as shown in formula (I) or (II):

[0038]

[0039] Wherein, R1 or R2 represents one of the following: diester group of CH3CH2O-CO-CH-CO-OCH2CH3, diester group of CH3CH2O-CO-C-CO-OCH2CH3, chiral ester group of CH3CH-CO-O-CH3, hydroxyl group of CH2CH2-OH, acrylate group of CH2CH-CO-OCH2CH2, sodium sulfonate group of CH2CH2CH2-SO3Na, or isocyanate group.

[0040] A second aspect of this invention discloses a method for preparing an organic photocatalyst based on diphenylcarbazole. This organic photocatalyst is divided into a type I free radical polymerization photocatalyst and a type II free radical polymerization photocatalyst. The type II free radical polymerization photocatalyst is prepared by reacting with the type I free radical polymerization photocatalyst. Different substances are prepared by different reactions, depending on the substituents. The diphenylcarbazole can be 2,7-diphenylcarbazole or 1,6-diphenylcarbazole. In the following description, 2,7-diphenylcarbazole is used as raw material a, and 1,6-diphenylcarbazole is used as raw material b.

[0041] Specifically, the free radical polymerization photocatalyst with chemical structural formula (I) is prepared by reacting raw material a and other first raw materials through a nucleophilic substitution reaction on saturated carbon, an ammonolytic ring-opening reaction, a nucleophilic substitution reaction on carbonyl group, or a nucleophilic addition reaction. Raw material a is 2,7-diphenylcarbazole, with the following chemical structural formula:

[0042]

[0043] Specifically, the free radical polymerization photocatalyst with chemical structural formula (II) is prepared by reacting raw material c and another raw material with a nucleophilic substitution reaction on saturated carbon, an ammonolytic ring-opening reaction, a nucleophilic substitution reaction on carbonyl group, or a nucleophilic addition reaction. Raw material c is 1,6-diphenylcarbazole, with the following chemical structural formula:

[0044]

[0045] In some embodiments of the present invention, R1 or R2 in a class of free radical polymerization photocatalysts is a diester group of CH3CH2O-CO-CH-CO-OCH2CH3, a diester group of CH3CH2O-CO-C-CO-OCH2CH3, or a chiral ester group of CH3CH-CO-O-CH3, which is prepared by nucleophilic substitution reaction on the saturated carbon of a halide and diphenylcarbazole.

[0046] In the specific reaction process, diphenylcarbazole is prepared by reacting with a halogenated product. The halogenated product can be diethyl bromomalonate, diethyl dibromomalonate, methyl (R)-(+)-2-chloropropionate, or methyl (S)-(-)-2-chloropropionate, which undergoes a nucleophilic substitution reaction.

[0047] More specifically, diphenylcarbazole reacts with diethyl bromomalonate to form a diester group of CH3CH2O-CO-CH-CO-OCH2CH3; diphenylcarbazole reacts with diethyl bromomalonate to form a diester group of CH3CH2O-CO-C-CO-OCH2CH3; and diphenylcarbazole reacts with methyl (R)-(+)-2-chloropropionate or methyl (S)-(-)-2-chloropropionate to form a chiral ester group of CH3CH-CO-O-CH3.

[0048] In some embodiments of the present invention, R1 or R2 in a type of free radical polymerization photocatalyst is a hydroxyl group of CH2CH2-OH or a sodium sulfonate group of CH2CH2CH2-SO3Na, which is prepared by an ammonolytic ring-opening reaction of diphenylcarbazole and ethylene carbonate or 1,3-propanesulfonate lactone. The resulting product is a type of free radical polymerization photocatalyst.

[0049] In some embodiments of the present invention, a type of free radical polymerization photocatalyst in which R1 or R2 is a hydroxyl group of CH2CH2-OH is used as an intermediate, which can further react with acryloyl chloride through a nucleophilic substitution reaction on the carbonyl group to generate a type of free radical polymerization photocatalyst, wherein R1 or R2 in the type of free radical polymerization photocatalyst is an acrylate group of CH2CH-CO-OCH2CH2.

[0050] In some embodiments of the present invention, a type of free radical polymerization photocatalyst in which R1 or R2 is a hydroxyl group of CH2CH2-OH is used as an intermediate, which can further undergo a nucleophilic addition reaction with hexamethylene diisocyanate trimer to generate a type II free radical polymerization photocatalyst, wherein R1 or R2 in the type II free radical polymerization photocatalyst is a trimeroisocyanate group.

[0051] More specifically, regarding the above description, all reaction types and reaction formulas are as follows:

[0052] Type 1: Nucleophilic substitution reaction on saturated carbon

[0053] Diphenylcarbazole and its halogenated derivative undergo a nucleophilic substitution reaction in an organic solvent under the catalysis of sodium tert-butoxide, yielding the product and generating a diester group of CH3CH2O-CO-CH-CO-OCH2CH3, a diester group of CH3CH2O-CO-C-CO-OCH2CH3, or a chiral ester group of CH3CH-CO-O-CH3, with R1 or R2 being either a diester group or a chiral ester group.

[0054] In the following exemplary reaction formula, reactant a is 2,7-diphenylcarbazole, reactant c is 1,6-diphenylcarbazole, reactant b is a brominated derivative with R1, and reactant d is a chlorinated derivative with R1.

[0055]

[0056]

[0057] In the nucleophilic substitution reaction on saturated carbon in step (1), the reaction temperature is 25-140℃ and the reaction time is 1-8h. There is no particular limitation on the type of organic solvent used in the reaction. As long as it can fully dissolve the raw material and has no adverse effect on the reaction, it can be used, such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, etc.

[0058] Type 2, Ammonolysis ring-opening reaction

[0059] Raw material a and lactones, raw material f being ethylene carbonate and raw material g being 1,3-propanesulfonate lactone, react in an organic solvent under the catalysis of sodium hydroxide to obtain the product.

[0060] The intermediate a generated by the following reaction formula (V) is both a product generated in the reaction of this invention and can also be used as intermediate a in subsequent reactions. R1 in intermediate a is a hydroxyl group of CH2CH2-OH, and R1 in the product of the second reaction formula is a sodium sulfonate group of CH2CH2CH2-SO3Na.

[0061]

[0062] In the ring-opening reaction of step (2), the reaction temperature is 25-130℃ and the reaction time is 8-12h. There is no particular limitation on the type of organic solvent used in the reaction. As long as it can fully dissolve the raw materials and has no adverse effect on the reaction, it can be used, such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, etc.

[0063] Type 3: Nucleophilic substitution reaction on the carbonyl group

[0064] Intermediate a and starting material h undergo a nucleophilic substitution reaction at the carbon group in an organic solvent under the catalysis of triethylamine to give the product, where h is acryloyl chloride. In this reaction, the R1 corresponding to the product is an acrylate group of CH2CH-CO-OCH2CH2.

[0065]

[0066] When intermediate a undergoes a nucleophilic substitution reaction at the carbonyl group, the reaction temperature should be controlled at 0°C with the acyl chloride added dropwise, and then slowly raised to room temperature after the addition is complete. There are no particular limitations on the type of organic solvent used in the reaction; any solvent that can fully dissolve the starting material and has no adverse effect on the reaction can be used, such as dichloromethane, dichloroethane, tetrahydrofuran, etc.

[0067] Type 4, nucleophilic addition reaction

[0068] Intermediate a and starting material i undergo a nucleophilic addition reaction in an organic solvent under the catalysis of dibutyltin dilaurate (DBTDL) to obtain the product. Starting material i is a hexamethylene diisocyanate trimer, and the product is generated. The R1 corresponding to the product is a trimeroisocyanate group.

[0069]

[0070] When intermediate a undergoes a nucleophilic substitution reaction on the carbonyl group, the reaction temperature is 80-120℃ and the reaction time is 1-2 hours. There are no particular limitations on the type of organic solvent used in the reaction. As long as it can fully dissolve the raw material and has no adverse effect on the reaction, it can be used, such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, etc.

[0071] The above-mentioned applications of diphenylcarbazole-based organic photocatalysts in the field of photocuring.

[0072] In the above preparation method, the raw materials used are all known compounds in the prior art, which can be commercially purchased or easily prepared according to known synthetic methods. Furthermore, the reactions involved in steps (1)-(x) are all conventional reactions for synthesizing similar compounds in the art. After understanding the synthetic approach disclosed in this invention, those skilled in the art can easily determine the specific reaction conditions.

[0073] The following description, in conjunction with specific embodiments, provides further details.

[0074] Example 1. (Synthesis of Compound 1)

[0075]

[0076] 3.19 g (0.01 mol) of starter a, 1.92 g (0.02 mol, 2 equiv) of sodium tert-butoxide, and 50 mL of N,N-dimethylformamide were added to a 250 mL three-necked flask. The mixture was stirred under a nitrogen atmosphere until the solid was completely dissolved. Then, 3.59 g (0.015 mol) of starter 1b was added dropwise to the reaction system. The mixture was stirred at room temperature for 30 min, then heated and refluxed under nitrogen protection for 1 h. After the reaction was complete, the solvent was rotary evaporated, and the resulting solid was dissolved in dichloromethane. The solid was washed three times with dilute hydrochloric acid, pure water, and saturated sodium chloride aqueous solution, respectively. Finally, it was dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation. The solid was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 8:1). The eluent was rotary evaporated to obtain a white solid powder, which was dried in an oven at 80 °C for 2 h to give compound 2, with a yield of 86%.

[0077] The structural characterization data of the product are shown below:

[0078] 1H NMR(400MHz,Chloroform-d)δ8.17–8.10(m,2H),7.74–7.67(m,4H),7.62(d,J=2.2Hz,2H),7.58–7 .43(m,7H),7.37(tq,J=5.1,1.6Hz,2H),6.10–6.05(m,1H),4.35–4.24(m,4H),1.29–1.18(m,6H); 13 C NMR (101MHz, Chloroform-d) δ165.70,141.85,141.09,139.43,128.80,127.55,127.17,122.75,120.57,120.07,108.41,62.69,60.13,14.02.

[0079] MS(m / z): 478(M+1) +

[0080] Example 2. (Synthesis of Compound 2)

[0081]

[0082] 3.19 g (0.01 mol) of starting material c, 1.92 g (0.02 mol, 2 equiv) of sodium tert-butoxide, and 50 mL of N,N-dimethylformamide were added to a 250 mL three-necked flask. The mixture was stirred under a nitrogen atmosphere until the solid was completely dissolved. Then, 3.59 g (0.015 mol) of starting material 1b was added dropwise to the reaction system. The mixture was stirred at room temperature for 30 min, then heated and refluxed under nitrogen protection for 1 h. After the reaction was complete, the solvent was rotary evaporated, and the resulting solid was dissolved in dichloromethane. The solid was washed three times with dilute hydrochloric acid, pure water, and saturated sodium chloride aqueous solution, respectively. Finally, it was dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation. The solid was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 8:1). The eluent was rotary evaporated to obtain a white solid powder, which was dried in an oven at 80 °C for 2 h to obtain compound 2, with a yield of 89%.

[0083] The structural characterization data of the product are shown below:

[0084] 1 H NMR(400MHz,Chloroform-d)δ8.16(d,J=2.2Hz,2H),7.65–7.55(m,6H),7.54(dd,J=7.2,2.1Hz,2H ),7.50–7.40(m,5H),7.40–7.34(m,1H),6.10(s,1H),4.24(q,J=6.4Hz,4H),1.29(t,J=6.3Hz,6H).

[0085] MS(m / z): 478(M+1) +

[0086] Example 3. (Synthesis of Compound 3)

[0087]

[0088] 0.96 g (3 mmol) of starter a and 10 mL of anhydrous DMF were added to a 250 mL three-necked flask. Under a nitrogen atmosphere, 0.18 g of NaH (60%, 4.5 mmol, 1.5 equiv) was added and stirred for 15 min until the solid was completely dissolved. Then, 0.95 g (3 mmol) of starter 3b dissolved in a small amount of anhydrous DMF was added dropwise to the reaction system, and the reaction was carried out at room temperature for 24 h. After the reaction was completed, the mixture was quenched with water, and a white powder was obtained after precipitation. The powder was washed with n-hexane and dried. Purification was performed by silica gel column chromatography (petroleum ether: ethyl acetate = 3:1). The eluent was rotary evaporated to obtain a white solid powder, which was dried in an oven at 80 °C for 2 h to give compound 3, with a yield of 64%.

[0089] The structural characterization data of the product are shown below:

[0090] 1 H NMR(400MHz,Chloroform-d)δ8.14(d,J=8.0Hz,4H),7.77–7.70(m,8H),7.59(s,4H), 7.53–7.45(m,13H),7.41–7.33(m,4H),4.45(q,J=7.2Hz,4H),1.48(t,J=7.2Hz,7H); 13 C NMR (101MHz, Chloroform-d) δ142.36,141.13,139.32,128.93,127.76,127.22,122.15,120.83,118.89,107.17,37.68,14.03.

[0091] MS(m / z): 795(M+1) +

[0092] Example 4. (Synthesis of Compound 4)

[0093]

[0094] 3.19 g (0.01 mol) of starter a, 1.92 g (0.02 mol, 2 equiv) of sodium tert-butoxide, and 50 mL of N,N-dimethylformamide were added to a 250 mL three-necked flask. The mixture was stirred under a nitrogen atmosphere until starter a was fully dissolved. Then, 1.84 g (0.015 mol) of starter 4b was added dropwise to the reaction system. The mixture was stirred at room temperature for 30 min, then heated and refluxed under nitrogen protection for 18 h. After the reaction was complete, the solvent was rotary evaporated, and the resulting solid was dissolved in dichloromethane. The solid was washed three times with dilute hydrochloric acid, pure water, and saturated sodium chloride solution, respectively. Finally, it was dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation. The solid was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 8:1). The eluent was rotary evaporated to obtain a white solid powder, which was dried in an oven at 80 °C for 2 h to give compound 4, with a yield of 75%.

[0095] The structural characterization data of the product are shown below:

[0096] 1 H NMR(400MHz,Chloroform-d)δ8.14(d,J=8.0Hz,2H),7.74–7.67(m,4H),7.56(d,J=1.4Hz,2H),7 .54–7.44(m,6H),7.42–7.33(m,2H),5.52(q,J=7.3Hz,1H),3.70(s,3H),1.89(d,J=7.2Hz,3H).

[0097] MS(m / z): 406(M+1) +

[0098] Example 5. (Synthesis of Compound 5)

[0099]

[0100] 3.19 g (0.01 mol) of starter a, 1.92 g (0.02 mol, 2 equiv) of sodium tert-butoxide, and 50 mL of N,N-dimethylformamide were added to a 250 mL three-necked flask. The mixture was stirred under a nitrogen atmosphere until starter a was completely dissolved. Then, 1.84 g (0.015 mol) of starter 5b was added dropwise to the reaction system. The mixture was stirred at room temperature for 30 min, then heated and refluxed under nitrogen protection for 18 h. After the reaction was complete, the solvent was rotary evaporated, and the resulting solid was dissolved in dichloromethane. The solid was washed three times with dilute hydrochloric acid, pure water, and saturated sodium chloride aqueous solution, respectively. Finally, it was dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation. The solid was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 8:1). The eluent was rotary evaporated to obtain a white solid powder, which was dried in an oven at 80 °C for 2 h to obtain compound 5, with a yield of 70%.

[0101] The structural characterization data of the product are shown below:

[0102] 1 H NMR(400MHz,Chloroform-d)δ8.14(d,J=8.1Hz,2H),7.70(dd,J=8.3,1.3Hz,4H),7.56(d,J=1.4Hz,2 H),7.54–7.44(m,6H),7.42–7.33(m,2H),5.52(q,J=7.3Hz,1H),3.70(s,3H),1.89(d,J=7.2Hz,3H).

[0103] MS(m / z): 406(M+1) +

[0104] Example 6. (Synthesis of Compound 6)

[0105] Step (1): Preparation of intermediate 6a

[0106]

[0107] 3.19 g (0.01 mol) of raw material a, 0.8 g (0.02 mol, 2 equiv) of sodium hydroxide, and 50 mL of N,N-dimethylformamide were added to a 250 mL three-necked flask. The mixture was stirred under a nitrogen atmosphere until the solid was completely dissolved. Then, 4.4 g (0.05 mol) of raw material 6b, dissolved in a small amount of N,N-dimethylformamide, was added dropwise to the reaction system. The mixture was stirred at room temperature for 30 min, then heated and refluxed under nitrogen protection for 24 h. After the reaction was completed, 200 mL of pure water was added to obtain a white precipitate. After drying, the precipitate was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 8:1). The eluent was rotary evaporated to obtain a white solid powder, which was dried in an oven at 80 °C for 2 h to obtain intermediate 6a, with a yield of 78%.

[0108] The structural characterization data of the product are shown below:

[0109] 1 H NMR(400MHz,Chloroform-d)δ8.13(d,J=8.0Hz,2H),7.75–7.68(m,4H),7.65(d,J=1.5Hz ,2H),7.53–7.44(m,6H),7.42–7.33(m,2H),4.57(t,J=5.4Hz,2H),4.10(t,J=5.4Hz,2H); 13C NMR (101MHz, Chloroform-d) δ141.80,141.59,139.24,128.64,127.43,127.00,121.88,120.48,119.01,107.22,61.43,45.35.

[0110] MS(m / z): 364(M+1) +

[0111] Step (2): Preparation of compound 6

[0112]

[0113] 1.09 g (3 mmol) of intermediate 6a was dissolved in 30 mL of dichloromethane, followed by the addition of 0.68 g (6.7 mmol) of triethylamine. The mixture was cooled in an ice bath to maintain the system temperature below 5 °C. 0.41 g (4.5 mmol) of starting material 6b was dissolved in 10 mL of dichloromethane and added dropwise to the reaction system under a nitrogen atmosphere, with constant monitoring of the system temperature to maintain it below 5 °C. The addition was completed within 30 min. After the addition was complete, the reaction system was gradually raised to room temperature and the reaction was allowed to proceed for 24 h. After the reaction was complete, the solution was filtered, the solvent was removed by rotary evaporation, and the product was extracted with ethyl acetate. The product was then washed with 5% sodium hydroxide aqueous solution, pure water, and saturated sodium chloride aqueous solution, respectively. Finally, it was dried with anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain a white solid. This solid was dried in an oven at 80 °C for 2 h to obtain compound 6, with a yield of 90%.

[0114] The structural characterization data of the product are shown below:

[0115] 1 H NMR(400MHz,Chloroform-d)δ8.13(d,J=7.6Hz,2H),7.63–7.55(m,8H),7.48–7.41(m,4H),7.41–7.35(m,2H),6.16–6.06(m,1H),6 .06–5.99(m,1H),5.94(dd,J=15.7,3.9Hz,1H),4.66(dt,J=15.6,4.1Hz,1H),4.57(dt,J=15.4,4.2Hz,1H),4.43(t,J=4.1Hz,2H); 13C NMR(101MHz,Chloroform-d)δ169.19,141.71,141.47,141.10,132.61,131. 34,131.26,130.04,129.48,125.25,125.14,123.32,112.96,64.93,44.69.

[0116] MS(m / z): 418(M+1) +

[0117] Example 7. (Synthesis of Compound 7)

[0118]

[0119] 3.19 g (0.01 mol) of reactant a, 1 g (0.025 mol, 2.5 equiv) of sodium hydroxide, and 50 mL of N,N-dimethylformamide were added to a 250 mL three-necked flask under N2 protection. Then, 3.05 g (0.025 mol, 2.5 equiv) of reactant 7b, dissolved in a small amount of N,N-dimethylformamide, was added dropwise to the reaction system. The reaction was carried out at room temperature for 24 h under N2 atmosphere. After the reaction was complete, the solvent was removed by rotary evaporation, and the product was dissolved in 2.4 M HCl overnight. The pH was then adjusted to neutral using a saturated NaHCO3 aqueous solution, and the product was purified by reverse chromatography (H2O:MeOH = 95:5) to give compound 7 in 68% yield.

[0120] The structural characterization data of the product are shown below:

[0121] 1 H NMR(400MHz, Methanol-d4)δ8.01(d,J=7.7Hz,2H),7.67–7.59(m,6H),7.53(dd,J=7.7,2.1Hz,2H),7 .50–7.45(m,3H),7.45–7.36(m,3H),4.34(t,J=7.0Hz,2H),3.35(s,1H),2.16(tt,J=9.7,7.0Hz,2H).

[0122] Example 8. (Synthesis of Compound 8)

[0123]

[0124] 3.63 g (0.01 mol) of intermediate 6a and 20 mL of N,N-dimethylformamide were added to a 100 mL three-necked flask and stirred until the solid was completely dissolved. Then, 1.92 g of raw material 8b was added and stirred evenly. 1 μL of dibutyltin dilaurate was added and reacted at 120 °C for 30 min. The solvent was removed by rotary evaporation to obtain compound 8 with a yield of 100%.

[0125] The structural characterization data of the product are shown below:

[0126] 1 H NMR (400MHz, DMSO-d6) δ8.19(dd,J=12.6,8.0Hz,5H),7.92(d,J=1.5Hz,3H),7.82(tq,J=8.6,4.3,3.6H z,13H),7.56–7.43(m,17H),7.43–7.32(m,5H),7.03(s,1H),4.93(t,J=5.6Hz,1H),4.78–4.71(m,2H),4 .61(t,J=5.7Hz,2H),4.46–4.39(m,3H),3.87(q,J=5.7Hz,2H),3.66(s,2H),2.94(s,1H),2.87–2.79(m ,2H),1.50(s,2H),1.42(s,2H),1.30(s,2H),1.22(s,3H),1.16(s,3H),1.08(s,3H),0.88–0.78(m,1H); 13 C NMR(101MHz,DMSO-d6)δ156.26,148.98,141.92,141.68,141.46,141.38,138.40,138.19,129.11,129.04,127.39, 121.57,121.46,120.84,118.49,118.24,108.05,107.64,62.32,60.02,45.39,42.30,30.18,29.33,27.37,25.99.

[0127] MS(m / z): 1596(M+1) +

[0128] Compounds 9-16, as shown in Table 1 below, were prepared from the corresponding raw materials according to the methods of Examples 1-8.

[0129] Table 1.

[0130]

[0131]

[0132] Performance Evaluation

[0133] The photocatalytic curing performance of the organic photocatalysts based on the diphenylcarbazole structure shown in formulas (I) and (II) of this invention was evaluated by formulating representative photocurable resin compositions. The specific steps are as follows:

[0134] (1) Prepare a light-curing resin composition with the following composition:

[0135] Acryloylmorpholine 100 parts by weight;

[0136] 20 parts by weight of trimethylolpropane triacrylate;

[0137] 1 part by weight of photocatalytic curing agent.

[0138] In the above composition, the photocatalytic curing agent is the organic photocatalyst based on the diphenylcarbazole structure shown in Example 3 of this invention.

[0139] (2) Curing performance test

[0140] Stir the above composition to ensure uniform mixing of all components. Then, pour the mixed composition into a silicone or long glass mold, or coat it onto the surface of the template by scraping or spin coating. Irradiate the mixture with an LED curing lamp of 365nm or 405nm wavelength to polymerize and cure the composition, thereby obtaining a cured product in bulk or film form.

[0141] The curing performance test results are shown in Table 2.

[0142] 1 Compound 1 Colorless and transparent Smooth and hard Odorless 22cm 2 Compound 2 Colorless and transparent Smooth and hard Odorless 17cm 3 Compound 3 Colorless and transparent Smooth and hard Odorless 20cm

[0143] In summary, the organic photocatalysts based on the diphenylcarbazole structure disclosed in this invention exhibit excellent application performance, good photocatalytic curing effect, and advantages such as low addition amount, high curing efficiency, large curing depth, and low odor, showing good application prospects in the field of photocuring.

[0144] In this document, relational terms such as "first" and "second" are used only to distinguish a particular entity or operation and do not necessarily require or imply an actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0145] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it; although referring to the foregoing

[0146] Example

[0147] The present invention has been described in detail. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0148] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a free radical polymerization photocatalyst based on diphenylcarbazole, characterized in that, The free radical polymerization photocatalyst is: or The free radical polymer photocatalyst was prepared by a nucleophilic substitution reaction on saturated carbon via diphenylcarbazole and other raw materials. Specifically, the 2,7-diphenylcarbazole reacts with other raw materials to generate compound 1, which is a free radical polymerization photocatalyst. The 3,6-diphenylcarbazole reacts with other raw materials to generate compound 2, a free radical polymerization photocatalyst. The other raw materials are halogenated compounds, and the halogenated compounds are diethyl bromomalonate.

2. A free radical polymerization photocatalyst based on diphenylcarbazole prepared by the method described in claim 1, characterized in that, The chemical structural formula is: or .

3. A photocuring application of the diphenylcarbazole-based free radical polymerization photocatalyst as described in claim 2, characterized in that, The free radical polymerization photocatalyst is used to initiate and catalyze the free radical polymerization of acrylamide monomers under ultraviolet or visible light irradiation.

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