A polymerizable disulfide, its preparation method and uses

Abstract

This invention relates to a polymerizable disulfide, its preparation method, and its uses, belonging to the fields of polymer chemistry and photopolymerization. It is proposed based on the significant volume shrinkage inherent in LED free radical photopolymerization. The beneficial effects of this invention are that the disclosed polymerizable disulfide compound can reduce the volume shrinkage of 405nm LED light-induced free radical photopolymerization, while also possessing initiation and polymerization properties. Furthermore, this disulfide can improve the heat resistance of photocurable materials, showing great application potential in the field of LED photopolymerization.

Description

Technical Field

[0001] This invention relates to LED photopolymerization systems, and describes the preparation method and applications of disulfides with photoinitiation and volume shrinkage reduction capabilities, belonging to the field of polymer chemical materials technology. Background Technology

[0002] In traditional photopolymerization technology, mercury lamps as the light source have drawbacks such as high energy consumption, slow start-up, and environmental pollution. In contrast, LED photopolymerization technology, using LEDs as the light source, offers advantages such as long lifespan, low energy consumption, high controllability, and rapid response, and is currently showing a trend of gradually replacing traditional photopolymerization technologies that use mercury lamps as the light source. In traditional free radical photocuring, the rapid cross-linking between molecules restricts chain segment movement, and the conversion of long van der Waals distances between monomer molecules to shorter covalent bond distances after photopolymerization inevitably leads to a certain degree of volume shrinkage in the photocured material. This significantly affects the fine structure and mechanical properties of the photocured material, limiting its application in high-performance and high-precision fields. Therefore, reducing volume shrinkage is a crucial problem that urgently needs to be solved in the field of photopolymerization. Summary of the Invention

[0003] In view of the aforementioned state of the prior art, the inventors of this invention have conducted extensive and in-depth research on reducing volume shrinkage, aiming to discover a novel type of polymerizable disulfide monomer. This monomer, when introduced into a photocuring system, possesses advantages such as reducing volume shrinkage, initiating photopolymerization, and improving heat resistance. The inventors have discovered that introducing an α-carbonylamide group into the disulfide monomer results in a disulfide monomer that effectively initiates and reduces volume shrinkage in a 405nm wavelength LED photocuring system.

[0004] Therefore, one object of the present invention is to provide a disulfide monomer that contains not only disulfide bonds and polymerizable groups, but also α-dicarbonyl groups. A disulfide monomer with such a structure can effectively initiate and reduce volume shrinkage in 405 nm wavelength LED photopolymerization systems. Furthermore, this photocurable material also exhibits good heat resistance and abrasion resistance.

[0005] Another object of the present invention is to provide a method for preparing the disulfide monomer of the present invention. The preparation process is simple, easy to perform, under mild conditions, and inexpensive.

[0006] Another object of the present invention is to provide a photocurable composition comprising a disulfide monomer according to the present invention.

[0007] The final objective of this invention is to provide the application of the disulfide monomer of this invention in the field of LED photopolymerization.

[0008] The technical solution for achieving the above-mentioned objectives of this invention can be summarized as follows:

[0009] 1. A polymerizable disulfide of general formula (Ⅰ):

[0010]

[0011] M represents

[0012] Any one of the groups R1, R2, R3, R4, and R5 is taken from:

[0013]

[0014] The remaining groups in R1, R2, R3, R4, and R5 may be the same or different, and are independently selected from hydrogen, C1-C6 alkyl groups, and C1-C6 ether chains, with hydrogen, methyl, ethyl, n-propyl, and isopropyl being preferred; n ranges from 1 to 10.

[0015] 2. A method for preparing the polymerizable disulfide described in item 1 is as follows:

[0016] 1) Dissolve the olefinic hydroxy ester compound in organic solvent 1 and add it to a single-necked flask. Dissolve oxalyl chloride in organic solvent 1 at a certain molar ratio. Add the solution dropwise to the single-necked flask using a dropping funnel at 20-25℃. Stir the solution with a magnetic stirrer and keep it at the temperature for 0.5h. Then remove solvent 1 and excess oxalyl chloride by vacuum distillation to obtain intermediate product A.

[0017] 2) Dissolve the aromatic disulfide with active hydrogen in organic solvent 1, add a certain amount of alkaline organic substance as an acid-binding agent, dissolve intermediate product A in organic solvent 1 in a certain proportion, and slowly add it dropwise to a single-necked flask using a dropping funnel under 0℃ ice-water bath conditions. Stir with magnetic mechanical force and keep warm for 2 hours. Quench the reaction with saturated potassium carbonate aqueous solution, wash three times with saturated NaCl aqueous solution to separate and combine the organic phases, dry the organic phase with anhydrous sodium sulfate overnight, and obtain the disulfide by vacuum distillation and column chromatography.

[0018] 3. The method according to item 2, characterized in that the organic solvent 1 is selected from ethyl acetate, dichloromethane, tetrahydrofuran, N,N-dimethylformamide, toluene, xylene, preferably dichloromethane; the olefinic hydroxy ester compound is hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-[2-(2-hydroxyethoxy)ethoxy]ethyl 2-acrylate, 2-(2-hydroxyethoxy)ethyl methacrylate, 2-methyl-2-acrylate-2-hydroxybutyl ester, 4-hydroxybutyl acrylate; the molar ratio of the olefinic hydroxy ester compound to oxaloyl chloride is 1:1.2 to 1:1.5, preferably 1:1.2.

[0019] 4. The method according to item 2, characterized in that the basic organic compound is selected from triethylamine, pyridine, imidazole, diisopropylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene, preferably triethylamine and imidazole; the molar ratio of the intermediate product A to the aromatic disulfide with active hydrogen is 2.2:1 to 2.5:1, preferably 2.2:1.

[0020] 5. A composition cured by free radical photopolymerization, characterized in that it comprises the polymerizable disulfide described in item 1.

[0021] 6. The composition according to claim 5, characterized in that the composition comprises 1% to 10% of the disulfide and 90% to 99% of the photoreactive resin or active monomer; or comprises 1% to 8% of the polymerizable disulfide, 1% to 5% of the photoinitiator and 87% to 98% of the photoreactive resin or active monomer, based on the total weight of the composition.

[0022] 7. The composition according to item 6, characterized in that the photoreactive resin is selected from one or more of epoxy (meth)acrylate resin, polyurethane (meth)acrylate resin, polyester (meth)acrylate resin, polyether (meth)acrylate resin, and acrylated poly (meth)acrylate resin; the active monomer is one or more of monofunctional, difunctional, or polyfunctional (meth)acrylate monomers; and the photoinitiator is selected from one or more of free radical photoinitiators.

[0023] 8. The application of the polymerizable disulfide described in item 1 in the field of LED photopolymerization.

[0024] In the following description of the invention, unless otherwise expressly stated, all numerical values ​​in this application are to be regarded as being modified by the word "approximately". However, the inventors have reported the numerical values ​​in the embodiments as accurately as possible, although these numerical values ​​inevitably include a certain degree of error.

[0025] In this application, unless explicitly excluded, specific or preferred embodiments of the invention can be combined. Furthermore, the elements of the embodiments of this application are specific preferred selections of their corresponding higher-level technical features. If a higher-level technical feature can be combined with other higher-level features, then the elements of the embodiments, i.e., the specific preferred selections, can also be combined with those other higher-level features. These combinations should be considered part of the original description of this application.

[0026] The disulfide compound described in this invention can induce photopolymerization and reduce volume shrinkage under irradiation with a 405nm wavelength LED light source. The mechanism is as follows: Figure 1As shown, upon absorbing light energy, the weaker SS bonds in the disulfide compound molecules break, generating aryl sulfide radicals. Then, some of these aryl sulfide radicals attack the commercial monomers to generate primary carbon radicals, which rapidly initiate chain polymerization of the monomers. Other aryl sulfide radicals tend to recombine and revert to disulfide bonds. During photopolymerization, the reverted disulfide bonds continuously repeat the reversible "break-recovery" reaction. Accompanying this reversible process, the polymer network continuously undergoes a "contraction-expansion-contraction" volume adjustment process, thereby macroscopically reducing the volume shrinkage phenomenon of the photopolymer material.

[0027] The beneficial effects of this invention are that it is simple and effective compared with traditional methods for reducing volume shrinkage, and can be applied to the field of LED photopolymerization. It can not only effectively reduce the volume shrinkage of photopolymer materials, but also has a good ability to initiate photopolymerization in the long wavelength band (405nm). It has important theoretical significance and potential application value for the development of LED photopolymerization technology and the expansion of the application field of disulfide compounds.

[0028] Source of raw materials

[0029] Table 1. Main Reagents and Manufacturers

[0030]

[0031] Attached Figure Description

[0032] Figure 1 This invention provides an initiation mechanism diagram of disulfide compounds that have the ability to initiate and reduce volume shrinkage in LED photopolymerization systems.

[0033] Figure 2 These are the UV-Vis absorption spectra of the four disulfide compounds prepared in Examples 1, 2, 3, and 4.

[0034] Figure 3 These are the UV-Vis absorption spectra of the four disulfide compounds prepared in Examples 5, 6, 7, and 8.

[0035] Figure 4 The double bond conversion spectra of the four disulfide compounds prepared in Examples 1, 2, 3 and 4 under 405nm LED light source irradiation for the polymerization of complex monomers.

[0036] Figure 5 The double bond conversion spectra of the four disulfide compounds prepared in Examples 5, 6, 7 and 8 under 405nm LED light source irradiation for the polymerization of complex monomers.

[0037] Figure 6 The double bond conversion rate spectra of the four disulfide compounds prepared in Examples 1, 2, 3 and 4 under 405nm LED light source irradiation for the polymerization of complex monomers.

[0038] Figure 7 The double bond conversion rate spectra of the four disulfide compounds prepared in Examples 5, 6, 7 and 8 under 405nm LED light source irradiation for the polymerization of complex monomers.

[0039] Figure 8 The image shows the double bond conversion rate spectra of the disulfide compounds prepared in Example 1 with different amounts added under 405nm LED light source irradiation.

[0040] Figure 9 The image shows the double bond conversion rate spectra of the disulfide compounds prepared in Example 1 with different amounts added under 405nm LED light source irradiation.

[0041] Figure 10 This is a graph showing the volume shrinkage rate of the compound monomers induced by adding different amounts of disulfide prepared in Example 1 under 405nm LED light source irradiation;

[0042] Figure 11 These are the thermogravimetric curves of the cured films prepared in Example 1 with different amounts of disulfide added;

[0043] Example 1

[0044] The preparation of OHOBS, a disulfide with the ability to initiate and reduce volume shrinkage in LED photopolymerization, is described below:

[0045]

[0046] (a) Oxaloyl chloride (1.52 g, 12 mmol) was dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. Then, 2-hydroxyethyl acrylate (1.16 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The mixture was slowly added dropwise to the single-necked flask at a rate of 1–2 drops per second at room temperature (20–25 °C) with magnetic stirring. The reaction was maintained at this temperature for 0.5 h. After the reaction was complete, intermediate A was obtained by vacuum distillation.

[0047] (b) Under ice-water bath conditions, 2,2'-diaminodiphenyl disulfide (1.24 g, 5 mmol) and triethylamine (1.01 g, 10 mmol) were dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. The mixture was stirred thoroughly with a magnetic stirrer. Then, intermediate A (2.07 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The solution was slowly added dropwise to the single-necked flask at a rate of 1-2 drops per second, and the reaction was maintained at this temperature for 4 h. After the reaction was complete, a saturated potassium carbonate aqueous solution (20 mL) was added to the reaction system to quench the reaction. The reaction solution was washed with deionized water, and the organic phases were separated and combined. The organic phases were dried overnight with anhydrous Na₂SO₄ and distilled under reduced pressure to obtain a pale yellow mixture. The crude product was purified by column chromatography to obtain a pale yellow solid product, OHOBS, in 88% yield.

[0048] OHOBS's proton NMR data are 1 H NMR(400MHz,Chloroform-d)δ9.76(s,1H),8.36(dd,J=8.3,1.4Hz,1H),7.43–7.34(m,1H),7.28(dd,J=7.8,1.7Hz,1H),7.01(td,J=7.6,1 .4Hz,1H),6.43(dd,J=17.3,1.4Hz,1H),6.21–6.06(m,1H),5.86(dd,J=10.4,1.4Hz,1H),4.59–4.53(m,2H),4.48(dt,J=7.0,3.8Hz,2H).

[0049] OHOBS carbon spectral data are 13 C NMR (101MHz, Chloroform-d) δ165.78,159.98,152.91,138.40,136.87,132.31,131.82,127.76,125.59,123.45,120.28,77.30,65.07,61.62.

[0050] Example 2

[0051] The preparation of OHMOBS, a disulfide with the ability to initiate and reduce volume shrinkage in LED photopolymerization, is described below:

[0052]

[0053] (a) Oxaloyl chloride (1.52 g, 12 mmol) was dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. Then, 2-hydroxyethyl methacrylate (1.30 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The mixture was added dropwise to the single-necked flask at a rate of 1–2 drops per second under magnetic stirring at room temperature (20–25 °C) for 0.5 h. After the reaction was complete, intermediate A was obtained by vacuum distillation.

[0054] (b) Under ice-water bath conditions, 2,2'-diaminodiphenyl disulfide (1.24 g, 5 mmol) and triethylamine (1.01 g, 10 mmol) were dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. The mixture was stirred thoroughly with a magnetic stirrer. Then, intermediate A (2.21 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The solution was slowly added dropwise to the single-necked flask at a rate of 1-2 drops per second, and the reaction was maintained at this temperature for 4 h. After the reaction was complete, a saturated potassium carbonate aqueous solution (20 mL) was added to the reaction system to quench the reaction. The reaction solution was washed with deionized water, and the organic phases were separated and combined. The organic phases were dried overnight with anhydrous Na₂SO₄ and distilled under reduced pressure to obtain a pale yellow mixture. The crude product was purified by column chromatography to obtain a pale brown solid product OHMOBS in 75% yield.

[0055] The proton NMR data of OHMOBS are 1 H NMR(400MHz,Chloroform-d)δ9.82(s,1H),8.42(dd,J=8.3,1.3Hz,1H),7.48–7.38(m,1H),7.32(dd,J=7.7,1.6Hz,1H),7.05(t d,J=7.6,1.4Hz,1H),6.18(p,J=1.0Hz,1H),5.62(p,J=1.6Hz,1H),4.66–4.54(m,2H),4.54–4.45(m,2H),1.97(t,J=1.3Hz,3H).

[0056] OHMOBS carbon spectrum data are 13 C NMR (101MHz, Chloroform-d) δ167.00,160.01,152.95,138.41,136.86,135.70,132.33,126.49,125.58,123.45,120.29,65.10,61.81,18.28.

[0057] Example 3

[0058] The preparation of PHOBS disulfide, which has the ability to initiate and reduce volume shrinkage in LED photopolymerization, is described below:

[0059]

[0060] (a) Oxaloyl chloride (1.52 g, 12 mmol) was dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. Then, 2-hydroxyethyl acrylate (1.16 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The mixture was slowly added dropwise to the single-necked flask at a rate of 1–2 drops per second at room temperature (20–25 °C) with magnetic stirring. The reaction was maintained at this temperature for 0.5 h. After the reaction was complete, intermediate A was obtained by vacuum distillation.

[0061] (b) Under ice-water bath conditions, 4,4'-diaminodiphenyl disulfide (1.24 g, 5 mmol) and triethylamine (1.01 g, 10 mmol) were dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. The mixture was stirred thoroughly with a magnetic stirrer. Then, intermediate A (2.07 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The solution was slowly added dropwise to the single-necked flask at a rate of 1-2 drops per second, and the reaction was maintained at this temperature for 4 h. After the reaction was complete, 20 mL of saturated potassium carbonate solution was added to quench the reaction. The reaction mixture was washed with deionized water, and the organic phases were separated and combined. The organic phases were dried overnight with anhydrous Na₂SO₄ and distilled under reduced pressure to obtain a pale yellow mixture. The crude product was purified by column chromatography to obtain a pale yellow solid product, PHOBS, with a yield of 72%.

[0062] PHOBS proton spectrum data are 1 H NMR (500MHz, CDCl3 / DMSO) δ7.83–7.78(m,2H),7.58–7.52(m,2H),6.14–6.06(m,1H),5.99(dd,J=13.3,1.7Hz,2H),4.41–4.31(m,4H).

[0063] PHOBS carbon spectral data are 13 C NMR (101MHz, Chloroform-d) δ165.97,160.40,153.42,135.94,133.65,131.93,129.42,127.70,120.52,65.13,61.58.

[0064] Example 4

[0065] The preparation of PHMOBS, a disulfide with the ability to initiate and reduce volume shrinkage in LED photopolymerization, is described below:

[0066]

[0067] (a) Oxaloyl chloride (1.52 g, 12 mmol) was dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. Then, 2-hydroxyethyl methacrylate (1.30 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The mixture was added dropwise to the single-necked flask at a rate of 1–2 drops per second under magnetic stirring at room temperature (20–25 °C) for 0.5 h. After the reaction was complete, intermediate A was obtained by vacuum distillation.

[0068] (b) Under ice-water bath conditions, 4,4'-diaminodiphenyl disulfide (1.24 g, 5 mmol) and triethylamine (1.01 g, 10 mmol) were dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. The mixture was stirred thoroughly with a magnetic stirrer. Then, intermediate A (2.21 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The solution was slowly added dropwise to the single-necked flask at a rate of 1-2 drops per second, and the reaction was maintained at this temperature for 4 h. After the reaction was complete, a saturated potassium carbonate aqueous solution (20 mL) was added to the reaction system to quench the reaction. The reaction solution was washed with deionized water, and the organic phases were separated and combined. The organic phases were dried overnight with anhydrous Na₂SO₄ and distilled under reduced pressure to obtain a pale yellow mixture. The crude product was purified by column chromatography to obtain a pale yellow solid product PHMOBS in 68% yield.

[0069] The proton NMR data of PHMOBS are 1 H NMR(400MHz,Chloroform-d)δ8.93(s,1H),7.68–7.60(m,2H),7.59–7.47(m,2H),6.15(t,J=1 .3Hz,1H),5.62(p,J=1.6Hz,1H),4.64–4.57(m,2H),4.54–4.47(m,2H),1.95(t,J=1.3Hz,3H).

[0070] The carbon spectral data of PHMOBS are as follows 13 C NMR (101MHz, Chloroform-d) δ167.20,160.37,153.45,135.95,135.63,133.63,129.42,126.63,120.51,65.13,61.77,18.25.

[0071] Example 5

[0072]

[0073] (a) Oxaloyl chloride (1.52 g, 12 mmol) was dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. Then, 4-hydroxybutylacrylate (1.44 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The mixture was added slowly dropwise to the single-necked flask at a rate of 1–2 drops per second under magnetic stirring at room temperature (20–25 °C) for 0.5 h. After the reaction was complete, intermediate A was obtained by vacuum distillation.

[0074] (b) Under ice-water bath conditions, 2,2'-diaminodiphenyl disulfide (1.24 g, 5 mmol) and triethylamine (1.01 g, 10 mmol) were dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. The mixture was stirred thoroughly with a magnetic stirrer. Then, intermediate A (2.35 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The solution was slowly added dropwise to the single-necked flask at a rate of 1-2 drops per second, and the reaction was maintained at this temperature for 4 h. After the reaction was complete, a saturated potassium carbonate aqueous solution (20 mL) was added to the reaction system to quench the reaction. The reaction solution was washed with deionized water, and the organic phases were separated and combined. The organic phases were dried overnight with anhydrous Na₂SO₄ and distilled under reduced pressure to obtain a pale yellow mixture. The crude product was purified by column chromatography to obtain a pale yellow solid product, HBOBS, with a yield of 90%.

[0075] HBOBS proton spectrum data are 1 H NMR (500MHz, CDCl3 / DMSO) δ7.63–7.56(m,1H),7.54–7.47(m,1H),7.32–7.23(m,2H),6.15–6.06 (m,1H),6.00(dd,J=13.1,1.7Hz,2H),4.22–4.14(m,2H),4.14–4.05(m,2H),1.86–1.74(m,4H).

[0076] HBOBS carbon spectral data are 13 C NMR(125MHz,Chloroform-d)δ165.87,161.96,157.04,139.10,131.71,128.24 ,128.04,128.03,124.28,123.41,120.61,65.35,64.73,26.41,26.39,26.37.

[0077] Example 6

[0078]

[0079] (a) Oxaloyl chloride (1.52 g, 12 mmol) was dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. Then, 2-methyl-2-acrylate-2-hydroxybutyl ester (1.58 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The mixture was slowly added dropwise to the single-necked flask at a rate of 1–2 drops per second at room temperature (20–25 °C) with magnetic stirring. The reaction was maintained at this temperature for 0.5 h. After the reaction was complete, intermediate A was obtained by vacuum distillation.

[0080] (b) Under ice-water bath conditions, 2,2'-diaminodiphenyl disulfide (1.24 g, 5 mmol) and triethylamine (1.01 g, 10 mmol) were dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. The mixture was stirred thoroughly with a magnetic stirrer. Then, intermediate A (2.49 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The solution was slowly added dropwise to the single-necked flask at a rate of 1-2 drops per second, and the reaction was maintained at this temperature for 4 h. After the reaction was complete, a saturated potassium carbonate aqueous solution (20 mL) was added to the reaction system to quench the reaction. The reaction solution was washed with deionized water, and the organic phases were separated and combined. The organic phases were dried overnight with anhydrous Na₂SO₄ and distilled under reduced pressure to obtain a pale yellow mixture. The crude product was purified by column chromatography to obtain a pale brown solid product HBMOBS in 78% yield.

[0081] The proton NMR data of HBMOBS are 1 H NMR (500MHz, CDCl3 / DMSO) δ7.62–7.54(m,1H),7.54–7.46(m,1H),7.32–7.23(m,2H),5.97(dq,J=2.0,1.0Hz,1H),5.63 (dq,J=2.0,1.1Hz,1H),4.22–4.14(m,2H),4.18–4.09(m,2H),1.94(t,J=1.0Hz,3H),1.81(tdd,J=7.1,3.8,2.0Hz,4H).

[0082] The carbon spectral data of HBMOBS are as follows 13 C NMR(125MHz,Chloroform-d)δ167.55,161.96,157.04,139.04,136.62,128.09,12 7.86,125.06,124.28,123.20,120.71,65.77,65.35,26.34,26.20,26.18,18.26.

[0083] Example 7

[0084]

[0085] (a) Oxaloyl chloride (1.52 g, 12 mmol) was dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. Then, 2-[2-(2-hydroxyethoxy)ethoxy]ethyl 2-acrylate (2.04 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The mixture was slowly added dropwise to the single-necked flask at a rate of 1-2 drops per second under magnetic stirring at room temperature (20–25 °C) for 0.5 h. After the reaction was complete, intermediate A was obtained by vacuum distillation.

[0086] (b) Under ice-water bath conditions, 2,2'-diaminodiphenyl disulfide (1.24 g, 5 mmol) and triethylamine (1.01 g, 10 mmol) were dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. The mixture was stirred thoroughly with a magnetic stirrer. Then, intermediate A (2.95 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The solution was slowly added dropwise to the single-necked flask at a rate of 1-2 drops per second, and the reaction was maintained at this temperature for 4 h. After the reaction was complete, a saturated potassium carbonate aqueous solution (20 mL) was added to the reaction system to quench the reaction. The reaction solution was washed with deionized water, and the organic phases were separated and combined. The organic phases were dried overnight with anhydrous Na₂SO₄ and distilled under reduced pressure to obtain a pale yellow mixture. The crude product was purified by column chromatography to obtain a pale yellow solid product DOBS in 89% yield.

[0087] The DOBS proton spectrum data are 1 H NMR(500MHz, CDCl3 / DMSO) δ7.58–7.47(m,1H),7.28(dd,J=5.6,3.5Hz,1H),6.15–6.06 (m,0H),5.99(dd,J=13.2,1.6Hz,1H),4.28(td,J=7.1,1.1Hz,2H),3.67–3.60(m,4H).

[0088] DOBS carbon spectrum data are 13 C NMR(125MHz,Chloroform-d)δ166.20,161.52,156.98,139.10,131.68,128.23,12 8.06,127.88,124.28,123.39,120.65,70.69,70.67,69.23,69.10,64.63,64.12.

[0089] Example 8

[0090]

[0091] (a) Oxaloyl chloride (1.52 g, 12 mmol) was dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. Then, 2-(2-hydroxyethoxy)ethyl methacrylate (1.74 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The mixture was slowly added dropwise to the single-necked flask at a rate of 1–2 drops per second under magnetic stirring at room temperature (20–25 °C) for 0.5 h. After the reaction was complete, intermediate A was obtained by vacuum distillation.

[0092] (b) Under ice-water bath conditions, 2,2'-diaminodiphenyl disulfide (1.24 g, 5 mmol) and triethylamine (1.01 g, 10 mmol) were dissolved in 20 mL of anhydrous dichloromethane and added to a 100 mL single-necked flask. The mixture was stirred thoroughly with a magnetic stirrer. Then, intermediate A (2.65 g, 10 mmol) was dissolved in 10 mL of anhydrous dichloromethane and added to a constant-pressure dropping funnel. The solution was slowly added dropwise to the single-necked flask at a rate of 1-2 drops per second, and the reaction was maintained at this temperature for 4 h. After the reaction was complete, a saturated potassium carbonate aqueous solution (20 mL) was added to the reaction system to quench the reaction. The reaction solution was washed with deionized water, and the organic phases were separated and combined. The organic phases were dried overnight with anhydrous Na₂SO₄ and distilled under reduced pressure to obtain a pale yellow mixture. The crude product was purified by column chromatography to obtain a pale yellow solid product, DMOBS, in 76% yield.

[0093] The proton NMR data of DMOBS are 1 H NMR (500MHz, CDCl3 / DMSO) δ7.57–7.51(m,1H),7.54–7.48(m,1H),7.32–7.23(m,2H),5.94(dq,J=1.7,0.9Hz,1H),5.63( dq,J=2.0,1.0Hz,1H),4.31(t,J=7.1Hz,2H),4.20(t,J=7.0Hz,2H),3.65(dt,J=18.0,7.1Hz,4H),1.94(t,J=1.0Hz,3H).

[0094] The carbon spectral data of DMOBS are 13 C NMR(125MHz,Chloroform-d)δ167.11,161.52,156.98,139.10,135.99,128.17,12 7.86,125.61,124.24,123.31,120.68,69.24,69.21,64.68,64.65,64.09,18.26.

[0095] Example 9

[0096] The purpose of Example 9 is to illustrate that the ultraviolet absorption of the disulfides prepared in Examples 1-8 is above 400 nm.

[0097] Using anhydrous acetonitrile as a solvent, the disulfides prepared in Examples 1-8 were respectively prepared to a concentration of 1×10⁻⁶. -4 molL -1 The standard solutions were used to measure the ultraviolet absorption spectra of eight disulfides in the range of 200-500 nm using a UV-Vis spectrophotometer.

[0098] The measured UV-Vis absorption spectra of eight disulfides, as well as the molar extinction coefficients at the maximum absorption wavelength and specific wavelengths, are as follows: Figure 2 , Figure 3 As shown in Table 2, from Figure 2 He Ru Figure 3 It can be seen that the maximum absorption wavelength of the four disulfides is between 200-300 nm, and they also have some absorption above 400 nm. The introduction of the α-dicarbonyl group causes the molar extinction coefficient of all eight disulfide compounds to reach 50 M at 405 nm. -1 cm -1 The above even reaches 280M -1 cm -1 For example, OHOBS, OHMOBS, PHOBS, PHMOBS, HBOBS, HBMOBS, DOBS, and DMOBS have molar extinction coefficients of 50 M at 405 nm. -1 cm -1 280M -1 cm -1 50M -1 cm -1 60M -1 cm -1 70M -1 cm -1 280M -1 cm -1 50M -1 cm -1 and 270M -1 cm -1 Therefore, it can be ensured that the absorption wavelength of disulfide can match the LED light source with wavelengths above 400nm, thus better initiating 405nm LED photopolymerization.

[0099] Table 2 Maximum absorption wavelengths of disulfides (λ) max ) and its molar extinction coefficient (ε) at specific wavelengths.

[0100]

[0101] Example 10

[0102] The purpose of Example 10 is to demonstrate that the disulfides prepared in Examples 1-8 have a good ability to initiate the photopolymerization of (meth)acrylate monomers under irradiation conditions of 405nm LED light source.

[0103] Bis-GMA (Bis-GMA) and TEGDMA (Triethylene Glyceryl Methacrylate) were formulated into a composite monomer at a mass ratio of 4:6. The disulfide prepared in Examples 1-8 was added at a content of 1 wt% as the photoinitiator, and a composite initiator containing 1 wt% of the commercial photoinitiator camphorquinone (CQ) and 2 wt% of dimethylaminoethyl methacrylate (DMAEMA) was used as a control group. A 405 nm wavelength LED light source was used as the irradiation source, with a light intensity of 100 mW·cm⁻¹. -2 The double bond conversion rate of the photosensitive liquid during polymerization was monitored using a real-time infrared spectrometer (Thermo Fisher Scientific, Nicolet 5700). Measurements were taken at 1660-1600 cm⁻¹. -1 Changes in band area over time.

[0104] from Figure 4 , Figure 5 Double bond conversion curve and Figure 6 , Figure 7 The double bond conversion rate curves show that after 200 s of illumination, without the addition of other photoinitiators, the double bond conversion rates of the photosensitive solutions containing only eight disulfides all reached over 65%, and the maximum double bond conversion rates of OHOBS, OHMOBS, PHOBS, PHMOBS, HBMOBS, HBOBS, DMOBS, and DOBS were 1.94% s. -1 2.71%s -1 1.86%s -1 1.97%s -1 2.79%s -1 2.02%s -1 2.58%s -1 and 1.88%s -1 This indicates that all eight disulfides have a good ability to initiate the polymerization of (meth)acrylate monomers and can be applied to photopolymerization systems using 405nm LEDs as the light source.

[0105] Example 11

[0106] The purpose of Example 11 is to demonstrate that when the disulfide prepared in Example 1 is added in greater quantities under 405nm LED light source irradiation, the final double bond conversion rate and double bond conversion rate of the photopolymerization of (meth)acrylate monomers are both improved.

[0107] A compound monomer was prepared by mixing bisphenol A glycidyl methacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) in a mass ratio of 4:6. The photosensitive solution was prepared using the OHOBS disulfide prepared in Example 1 as the photoinitiator. The added content of OHOBS was 2.5 wt%, 5.0 wt%, 7.5 wt%, and 10.0 wt% (as a percentage of the total monomer weight), respectively. A 405 nm wavelength LED light source was used as the irradiation source, with a light intensity of 100 mW·cm. -2 The double bond conversion rate of the photosensitive liquid during polymerization was monitored using a real-time infrared spectrometer (Thermo Fisher Scientific, Nicolet 5700). Measurements were taken at 1660-1600 cm⁻¹. -1 Changes in band area over time.

[0108] from Figure 8 Double bond conversion curve and Figure 9 The double bond conversion rate curves show that, without the addition of other commercial photoinitiators, the polymerization rate and the double bond conversion rate under 200 s of illumination both increase with the increase of OHOBS content. When the OHOBS content is 10 wt%, the double bond conversion rate reaches over 80%. The maximum double bond conversion rate also gradually increases with the increase of OHOBS content from 2.5 wt% to 10 wt%, reaching 2.79% s. -1 3.03%s -1 3.06%s -1 and 3.72%s -1 .

[0109] Example 12

[0110] The purpose of Example 12 is to demonstrate that the disulfides prepared in Examples 1-8 have a good ability to reduce volume shrinkage during free radical photocuring under 405nm LED light source irradiation.

[0111] Taking the disulfide OFOBS prepared in Example 1 as an example, it was compared with the commercial photoinitiator camphorquinone (CQ) / dimethylaminoethyl methacrylate (DMAEMA) system (containing 1.0 wt% CQ and 2.0 wt% DMAEMA). Bisphenol A glycidyl methacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) were selected at a mass ratio of 4:6 to prepare a compound monomer, and the photosensitive solution was prepared according to the formulation in Table 3.

[0112] Table 3 Formulation of OHOBS-containing photosensitive solution

[0113]

[0114] Note: CQ: 1.0 wt%, DMAEMA: 2.0 wt%; Monomer: Bis-GMA / TEGDMA (4:6, mass ratio)

[0115] The volume shrinkage rate after curing was tested using a Keyence LK-G10 laser displacement sensor. First, the photosensitive liquid to be tested was dropped into a silicone mold with a diameter of 4 mm and a height of 1 mm, and then treated with a 10-filament PE film for oxygen barrier. An LED light source with a wavelength of 405 nm (illuminance: 100 mW / cm²) was used. -2 Irradiate the sample for ten minutes, and record the height of the photosensitive liquid before irradiation (l1) and after irradiation (l2) using a laser micrometer. The volume shrinkage rate of different systems is obtained using the following formula:

[0116]

[0117] The test results of OHOBS reducing volume shrinkage are as follows: Figure 10 As shown, when the content is 5.0 wt%, the volume shrinkage rate is the lowest at 5.01%, which is nearly half that of the commercial photoinitiator CQ system. This is mainly attributed to the reversible "break-recovery" property of disulfide bonds under UV-Vis irradiation and the continuous release of shrinkage stress generated during photopolymerization by intermolecular hydrogen bonding, thereby reducing volume shrinkage.

[0118] Example 13

[0119] The purpose of implementation 13 is to illustrate that the disulfides prepared in Examples 1-8 can improve the heat resistance of polymer films to a certain extent.

[0120] Taking the disulfide compound OHOBS prepared in Example 1 as an example, the photosensitive solution was prepared according to the formula in Table 3. Different photosensitive solutions were continuously irradiated with a 405nm LED light source for 10 minutes to cure into films (light intensity: 100mW / cm²). -2 The thermal stability of the cured film was tested using a thermogravimetric analyzer (DTG-60AH) under a nitrogen atmosphere. The test temperature range was 30–800℃, with a heating rate of 10℃ / min. -1 .

[0121] The test results of Example 13 are shown in Table 4 and Figure 11 As shown. The results indicate that although the initial decomposition temperature T of the system with added disulfide OHOBS is [not specified], [the following is unclear and likely incomplete: "as shown."] 5％ The initial decomposition temperature is slightly lower than that of the OHOBS-free cured film, and the maximum thermal weight loss temperature T0 is also slightly lower. max The results were all higher than those of the control group system without OHOBS, indicating that the prepared disulfide can improve the heat resistance of the polymer film to a certain extent.

[0122] Table 4. Thermogravimetric data of cured films

[0123]

[0124] Example 14

[0125] The purpose of Example 14 is to illustrate that the polymer films prepared from the disulfides in Examples 1-8 have good abrasion resistance.

[0126] Taking the disulfide compound OHOBS prepared in Example 1 as an example, the photosensitive solution was prepared according to the formula in Table 3. The prepared photosensitive solution was continuously irradiated with a 405nm LED light source for 10 minutes to cure into a film (light intensity: 100mW / cm²). -2 ).

[0127] Test Procedure: A Model 339 multi-functional alcohol eraser abrasion tester was used, with a Malaysian 7017R eraser as the abrasive. The test was conducted under a 500g load, with a friction distance of 10cm and a friction frequency of 100 times / minute. The experiment was repeated five times. The mass m0 of the film before wear and the mass m after wear were recorded. x (Record every 500 friction cycles) Calculate the friction loss using the following formula:

[0128] Friction loss = m0 - m x

[0129] The test results of Example 14 are shown in Table 5. The friction loss of the cured film containing disulfide OHOBS is slightly lower than that of the cured film sample without disulfide, indicating better friction resistance.

[0130] Table 5. Friction loss rate of disulfide compound-cured films

[0131]

Claims

1. A polymerizable disulfide of general formula (Ⅰ): （Ⅰ） M represents ; Any one of the groups R1, R2, R3, R4, and R5 is taken from: 、 、 、 ； The remaining groups in R1, R2, R3, R4, and R5 are the same or different, and are independently selected from hydrogen and C1 to C6 alkyl groups; n ranges from 1 to 10.

2. A polymerizable disulfide of general formula (Ⅰ) according to claim 1: characterized in that, R1, R2, R3, R4, and R5 are selected from hydrogen, methyl, ethyl, n-propyl, and isopropyl.

3. A method for preparing the polymerizable disulfide as described in claim 1 is as follows: 1) Dissolve the olefinic hydroxy ester compound in organic solvent 1 and add it to a single-necked flask. Dissolve oxalyl chloride in organic solvent 1 at a certain molar ratio. Add the solution dropwise to the single-necked flask using a dropping funnel at 20-25℃. Stir the solution with a magnetic stirrer and keep it at the temperature for 0.5 h. Then remove solvent 1 and excess oxalyl chloride by vacuum distillation to obtain intermediate product A. 2) Dissolve the aromatic disulfide with active hydrogen in organic solvent 1, add a certain amount of basic organic substance as an acid-binding agent, dissolve intermediate product A in organic solvent 1 in a certain proportion, and slowly add it dropwise to a single-necked flask using a dropping funnel under 0℃ ice-water bath conditions, use magnetic mechanical stirring and keep warm for 2 h, quench the reaction with saturated potassium carbonate aqueous solution, wash three times with saturated NaCl aqueous solution to separate and combine the organic phases, dry the organic phase with anhydrous sodium sulfate overnight, and obtain the disulfide by vacuum distillation and column chromatography.

4. The method according to claim 3, characterized in that, Organic solvent 1 is selected from ethyl acetate, dichloromethane, tetrahydrofuran, N,N-dimethylformamide, toluene, and xylene; the olefinic hydroxy ester compound is hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-[2-(2-hydroxyethoxy)ethoxy]ethyl 2-acrylate, 2-(2-hydroxyethoxy)ethyl methacrylate, 2-methyl-2-acrylate-2-hydroxybutyl ester, and 4-hydroxybutyl acrylate; the molar ratio of the olefinic hydroxy ester compound to oxaloyl chloride is 1:1.2 to 1:1.

5.

5. The method according to claim 3, characterized in that, Organic solvent 1 is dichloromethane; the molar ratio of olefinic hydroxy ester compound to oxaloyl chloride is 1:1.

2.

6. The method according to claim 3, characterized in that, The basic organic compound is selected from triethylamine, pyridine, imidazole, diisopropylamine, and 1,8-diazabicyclo[5.4.0]undec-7-ene; the molar ratio of the intermediate product A to the aromatic disulfide with active hydrogen is 2.2:1 to 2.5:

1.

7. The method according to claim 3, characterized in that, The basic organic compound is selected from triethylamine and imidazole; the molar ratio of intermediate product A to the aromatic disulfide with active hydrogen is 2.2:

1.

8. A composition cured by free radical photopolymerization, characterized in that, It includes the polymerizable disulfide as described in claim 1.

9. The composition according to claim 8, characterized in that, The composition comprises 1% to 10% of the disulfide and 90% to 99% of the photoreactive resin or active monomer; or comprises 1% to 8% of the polymerizable disulfide, 1% to 5% of the photoinitiator and 87% to 98% of the photoreactive resin or active monomer, based on the total weight of the composition.

10. The composition according to claim 9, characterized in that, The photoreactive resin is selected from one or more of epoxy (meth)acrylate resin, polyurethane (meth)acrylate resin, polyester (meth)acrylate resin, polyether (meth)acrylate resin, and acrylate-esterified poly (meth)acrylate resin; the active monomer is one or more of monofunctional, difunctional, or polyfunctional (meth)acrylate monomers; and the photoinitiator is selected from one or more of free radical photoinitiators.

11. The application of the polymerizable disulfide according to claim 1 in the field of LED photopolymerization.

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