Process for the preparation of a photocurable resin containing dynamic covalent boronic ester bonds
By introducing vinyl boric acid into the photocurable resin to form boron ester bonds with polyphenols, the recycling and processing problems of traditional thermosetting resins are solved, achieving self-healing and remodelability, and improving mechanical properties and environmental friendliness.
Patent Information
- Application Number
- CN202211314789.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-10-24
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2042-10-24
AI Technical Summary
Traditional thermosetting resins are difficult to recycle and process, have poor mechanical properties, cannot self-heal or require harsh repair conditions, and acrylate resins have problems such as hardness, solvent resistance and high cost in certain situations.
By introducing dynamic covalent bonds, boronic ester bonds are formed between vinylboric acid and polyphenols, catalyzing the dynamic transesterification of boronic ester bonds, enhancing the elongation at break and toughness of the material, and achieving self-healing function at room temperature.
It improves the material's remodelability and reprocessability, enhances its mechanical properties, and achieves self-healing capabilities. At the same time, it is simple to operate, has a fast response rate, and features energy saving, emission reduction, and environmental protection.
Smart Images
Figure CN115490816B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of preparation of novel polymer material photocurable resin, specifically relating to a method for preparing a photocurable material containing dynamic covalent bonds and exhibiting luminescence, which can be used in fields such as 3D printing. Background Technology
[0002] Photocurable materials are summarized as having "5E" characteristics: Efficient, Enabling, Economical, Energy Saving, and Environmentally Friendly. The main characteristics are environmental friendliness and speed, and their applications are primarily centered around these two features. Photocuring technology (UV) is a photoprocessing technique that uses ultraviolet light of a specific wavelength to rapidly polymerize liquid acrylate resin into a solid state. The photocuring reaction is essentially a light-initiated polymerization and cross-linking reaction. Acrylic resin is one of the most widely used photosensitive resins in UV-curable materials, possessing advantages such as light color, high transparency, chemical resistance, and strong adhesion. However, acrylate resin has certain drawbacks in specific applications, such as non-recyclability, insufficient mechanical properties, low hardness, poor solvent resistance, and high cost, which limit its further application. The substance obtained by photopolymerization of acrylate resin monomers is a thermosetting material. Thermosetting polymers, due to their permanent cross-linked structure, possess superior dimensional stability and creep resistance. It is precisely because of this cross-linked structure that its network cannot be easily destroyed, making the polymer difficult to process. Summary of the Invention
[0003] To address the challenges of recycling and processing traditional thermosetting resins, this invention introduces dynamic covalent bonds, granting them remodeling and reprocessing capabilities. Furthermore, by introducing vinylboric acid and polyphenols to form boron ester bonds, and with ortho-hydroxyl groups catalyzing the dynamic transesterification of these bonds, the material's elongation at break and toughness are enhanced. This invention also solves the problems of poor mechanical properties, the inability to balance remodeling and mechanical strength, and the lack of self-healing capabilities or demanding repair conditions. It ensures stable dynamic properties and achieves self-healing functionality at room temperature. Specifically, this invention is achieved through the following technical solutions:
[0004] The method for preparing a photocurable resin containing borate ester dynamic covalent bonds according to the present invention involves introducing borate esters during the preparation of the photocurable resin.
[0005] In the preparation method described above, preferably, the resin is an acrylate resin, an epoxy resin, or an unsaturated polyester.
[0006] In the above-described preparation method, preferably, the borate ester is mainly obtained by reacting vinylboric acid with polyphenols; the vinylboric acid is one or a mixture of more than one of 2-vinylphenylboric acid, 4-vinylphenylboric acid, and isopropenylboric acid; the polyphenol is one or a mixture of more than one of ellagic acid, tannic acid, quercetin, tetrahydroxybenzophenone, and 3,4-dihydroxybenzaldehyde. The inventors have discovered that inorganic boric acids lack the carbon-carbon double bond required for photocuring reactions and cannot be introduced into photocuring systems. On the other hand, ordinary boric acids react with a single hydroxyl group to form only a single boron-oxygen bond. The vinylboric acid of this invention can react with the ortho- or meta-dihydroxyl groups on the polyphenol to form a five-membered or six-membered boron ester, while other hydroxyl groups in the polyphenol, such as those at the already reacted ortho- or meta-positions, may catalyze the dynamic exchange of the borate ester, thereby reducing the activation energy of the transesterification.
[0007] In the above-described preparation method, preferably, the borate ester is prepared by the following method: vinylboric acid is dissolved in a solvent, polyphenols are added, then anhydrous magnesium sulfate is added, the reaction is carried out for 18-24 hours, and then filtered to purify. The solvent can be tetrahydrofuran, acetone, N,N-dimethylformamide, etc.
[0008] In the above-described preparation method, preferably, the purification involves rotary evaporating the filtered solution at 30-40°C to obtain a solid, washing with ether, filtering again, and then rotary evaporating the filtered solution to obtain the borate ester.
[0009] In the preparation method described above, preferably, the mass ratio of vinylboric acid to polyphenol is 1:2-4.
[0010] The preferred preparation method described above includes the following steps: dissolving the borate ester in a solvent, adding the photocurable resin monomer, rotary evaporating the mixed solution at 30-40°C for 3-6 hours to remove the solvent, and obtaining a homogeneous mixture; adding a photoinitiator, and vacuum stirring for 10-30 minutes to obtain a prepolymer; placing the prepolymer into a mold and curing it with UV for 1-3 minutes. The solvent can be tetrahydrofuran, acetone, N,N-dimethylformamide, etc.
[0011] In the preparation method described above, preferably, the prepolymer is vacuumed 1-3 times to remove air bubbles, and then the prepolymer is placed into the mold.
[0012] In the preparation method described above, preferably, the photocurable resin monomer is an acrylate monomer, which is one or a mixture of more than one of glycidyl methacrylate, tetrahydrofuran acrylate, isobornyl methacrylate, and isobornyl acrylate.
[0013] In the preparation method described above, preferably, the photoinitiator is one or a mixture of more than one of the following: TPO (2,4,6-trimethylbenzoyl-diphenylphosphine oxide), 184 (1-hydroxycyclohexylphenyl ketone), DMPA (2,2-dimethoxy-phenylacetophenone), DEAP (α,α'-ethoxyacetophenone), 2-methyl-2-(4-morpholino)-1-[4-(methylthio)phenyl]-1-propanone, 2-dimethylamino-2-benzyl-1-[4-(4-morpholino)phenyl]-1-butanone, ethyl 2,4,6-trimethylbenzoylphosphonate, HMPP (2-hydroxy-2-methyl-1-phenyl-1-propanone), and MBF (methyl benzoylcarbamate).
[0014] In the preparation method described above, preferably, the mass ratio of the photocurable resin monomer to the borate ester is 3-5:1; and the amount of photoinitiator is 0.5-2% of the total mass of the photocurable resin monomer and the borate ester.
[0015] In this invention, the boric acid group and the phenolic hydroxyl group of the polyphenol can react by mixing and stirring at room temperature for more than 18 hours. When the photocuring reaction is carried out with a photocurable resin monomer such as an acrylate monomer, a cross-linked polymer can be formed by adding a photoinitiator and irradiating with an ultraviolet mercury lamp (365nm).
[0016] This invention introduces dynamic covalent bonds of boron esters into the crosslinking network of resin polymers, enabling the resin polymers to exhibit classic thermosetting properties under certain conditions. However, after the dynamic covalent bonds are activated, the network topology can be repeatedly rearranged, resulting in the self-organizing and repairing properties of the network polymers.
[0017] The boron ester-containing dynamically covalently bonded resin prepared by this invention exhibits good elongation at break and toughness, effectively improving the material's service life, making it particularly suitable for the 3D printing field. Furthermore, the polymer prepared by this invention contains boron esters, and the boron ester bonds can undergo an exchange reaction at room temperature without external stimulation—the ortho- or meta-hydroxyl groups in the polyphenol can catalyze the dynamic exchange of boron esters, lowering the activation energy of ester exchange. Therefore, unlike typical self-healing materials, it does not require stringent conditions such as heating and pressurization to stimulate dynamic exchange, enabling this invention to effectively improve the material's reusability—achieving self-healing without external stimulation, further enhancing the remodeling and reprocessability of the photocurable resin material. Simultaneously, the photocurable resin preparation method of this invention is simple to operate, has a fast reaction rate, mild conditions, and high product yield—simple and efficient. The photocuring technology of this invention also has the advantages of energy saving, emission reduction, and environmental protection. Attached Figure Description
[0018] Figure 1This is a self-healing test of the photocurable resin containing boron ester dynamic covalent bonds obtained in this invention. In the figure, 1 is the resin material cut into two pieces, 2 is the resin material after self-healing, and 3 is the resin material placed in a constant temperature chamber. Detailed Implementation
[0019] The following embodiments are further illustrations of the present invention and serve as explanations of the technical content of the present invention. However, the essence of the present invention is not limited to the embodiments described below. Those skilled in the art can and should know that any simple changes or substitutions based on the spirit of the present invention should fall within the protection scope claimed by the present invention.
[0020] Example 1
[0021] Following the formulation of components for Example 1 in Table 1, 4-vinylphenylboronic acid and tannic acid were dissolved in tetrahydrofuran solvent. Anhydrous magnesium sulfate was added, and the mixture was magnetically stirred at room temperature for 24 hours to obtain a homogeneous product. The product was filtered and washed 3-5 times to remove anhydrous magnesium sulfate, and the solvent was removed by rotary evaporation. The solid product was washed 3-5 times with diethyl ether to remove unreacted 4-vinylphenylboronic acid. Then, the solvent and tetrahydrofuran acrylate monomer were added, mixed thoroughly, and rotary evaporated at 35°C for 4 hours. The photoinitiator TPO was then added, and the mixture was stirred at room temperature for 10 minutes to obtain a homogeneous prepolymer. The prepolymer was then degassed under vacuum for 10 minutes to obtain a bubble-free prepolymer. After curing with a UV mercury lamp for 2 minutes, a photocurable resin containing boron ester dynamic covalent bonds was obtained.
[0022] Example 2
[0023] Following the formulation of components for Example 2 in Table 1, 4-vinylphenylboronic acid and quercetin were dissolved in N,N-dimethylformamide. Anhydrous magnesium sulfate was added, and the mixture was magnetically stirred at room temperature for 18 hours to obtain a homogeneous product. The product was filtered and washed 3-5 times to remove anhydrous magnesium sulfate, and the solvent was removed by rotary evaporation. The solid product was washed 3-5 times with diethyl ether to remove unreacted vinylboronic acid. Tetrahydrofuran acrylate was then added, and the mixture was stirred at 50°C for 8 hours. Photoinitiator TPO was then added, and the mixture was stirred at room temperature for 10 minutes to obtain a homogeneous prepolymer. The prepolymer was then degassed under vacuum for 10 minutes to obtain a bubble-free prepolymer. After curing with a UV mercury lamp for 2 minutes, a photocurable resin containing boron ester dynamic covalent bonds was obtained.
[0024] Example 3
[0025] Following the formulation of components for Example 3 in Table 1, 2-vinylphenylboronic acid and ellagic acid were dissolved in tetrahydrofuran solvent. Anhydrous magnesium sulfate was added, and the mixture was magnetically stirred at room temperature for 20 hours to obtain a homogeneous product. The product was filtered and washed 3-5 times to remove anhydrous magnesium sulfate, and the solvent was removed by rotary evaporation. The solid product was washed 3-5 times with diethyl ether to remove unreacted vinylboronic acid. Then, solvent and isobornyl methacrylate were added, and the mixture was stirred at 55°C for 4 hours. Photoinitiator 184 was then added, and the mixture was stirred at room temperature for 10 minutes to obtain a homogeneous prepolymer. The prepolymer was then degassed under vacuum for 10 minutes to obtain a bubble-free prepolymer. After curing with a UV mercury lamp for 2 minutes, a photocurable resin containing boron ester dynamic covalent bonds was obtained.
[0026] Example 4
[0027] Following the formulation of components for Example 4 in Table 1, 4-vinylphenylboronic acid and tannic acid were dissolved in tetrahydrofuran solvent. Anhydrous magnesium sulfate was added, and the mixture was magnetically stirred at room temperature for 18 hours to obtain a homogeneous product. The product was filtered and washed 3-5 times to remove anhydrous magnesium sulfate, and the solvent was removed by rotary evaporation. The solid product was washed 3-5 times with diethyl ether to remove unreacted vinylboronic acid. Then, solvent and isobornyl acrylate were added, and the mixture was stirred at 60°C for 5 hours. The photoinitiator DMPA was then added, and the mixture was stirred at room temperature for 10 minutes to obtain a homogeneous prepolymer. The prepolymer was then degassed under vacuum for 10 minutes to obtain a bubble-free prepolymer. After curing with a UV mercury lamp for 2 minutes, a photocurable resin containing boron ester dynamic covalent bonds was obtained.
[0028] Example 5
[0029] Following the formulation of each component in Example 5 as shown in Table 1, 4-vinylphenylboronic acid and tetrahydroxybenzophenone were dissolved in acetone, and anhydrous magnesium sulfate was added. The mixture was magnetically stirred at room temperature for 24 hours to obtain a homogeneous product. The product was filtered and washed 3-5 times to remove anhydrous magnesium sulfate, and the solvent was removed by rotary evaporation. The solid product was washed 3-5 times with diethyl ether to remove unreacted vinylboronic acid. Then, solvent and isobornyl acrylate were added, and the mixture was stirred at 60°C for 4 hours. Next, photoinitiator MBF was added, and the mixture was stirred at room temperature for 10 minutes to obtain a homogeneous prepolymer. The prepolymer was then degassed under vacuum for 10 minutes to obtain a bubble-free prepolymer. This was cured under a UV mercury lamp for 2 minutes to obtain a photocurable resin containing boron ester dynamic covalent bonds.
[0030] Example 6
[0031] Following the formulation of each component in Example 6 as shown in Table 1, isopropenylboronic acid and tannic acid were dissolved in tetrahydrofuran, and anhydrous magnesium sulfate was added. The mixture was magnetically stirred at room temperature for 24 hours to obtain a homogeneous product. The product was filtered and washed 3-5 times to remove anhydrous magnesium sulfate, and the solvent was removed by rotary evaporation. The solid product was washed 3-5 times with diethyl ether to remove unreacted ethylenephenylboronic acid. Then, solvent and glycidyl methacrylate were added, and the mixture was stirred at 45°C for 6 hours. Photoinitiator 184 was then added, and the mixture was stirred at room temperature for 10 minutes to obtain a homogeneous prepolymer. The prepolymer was then degassed under vacuum for 10 minutes to obtain a bubble-free prepolymer. This was cured under a UV mercury lamp for 2 minutes to obtain a photocurable resin containing boron ester dynamic covalent bonds.
[0032] Comparative Example 1
[0033] According to the formulation of each component as shown in Table 1 (Comparative Example 1), succinic acid and 3,4-dihydroxybenzaldehyde were dissolved in acetone. Anhydrous magnesium sulfate was added, and the mixture was magnetically stirred at room temperature for 24 hours to obtain a homogeneous product. The product was filtered and washed 3-5 times to remove anhydrous magnesium sulfate, and the solvent was removed by rotary evaporation. The solid product was washed 3-5 times with diethyl ether to remove unreacted vinylboric acid. Then, solvent and glycidyl methacrylate were added, and the mixture was stirred at 60°C for 2 hours. The photoinitiator TPO was then added, and the mixture was stirred at room temperature for 10 minutes to obtain a homogeneous prepolymer. The prepolymer was then degassed under vacuum for 10 minutes to obtain a bubble-free prepolymer. After curing with a UV mercury lamp for 2 minutes, a photocurable resin without boron ester dynamic covalent bonds was obtained.
[0034] Comparative Example 2
[0035] Following the formulation of each component as shown in Comparative Example 2 in Table 1, terephthalic acid and tetrahydroxybenzophenone were dissolved in acetone. Anhydrous magnesium sulfate was added, and the mixture was magnetically stirred at room temperature for 24 hours to obtain a homogeneous product. The product was filtered and washed 3-5 times to remove anhydrous magnesium sulfate, and the solvent was removed by rotary evaporation. The solid product was washed 3-5 times with diethyl ether to remove unreacted vinylboric acid. Then, solvent and isobornyl acrylate were added, and the mixture was stirred at 35°C for 6 hours. The photoinitiator DMPA was then added, and the mixture was stirred at room temperature for 10 minutes to obtain a homogeneous prepolymer. The prepolymer was then degassed under vacuum for 10 minutes to obtain a bubble-free prepolymer. After curing with a UV mercury lamp for 2 minutes, a photocurable resin without boron ester dynamic covalent bonds was obtained.
[0036] Comparative Example 3
[0037] Common methods for preparing photocurable resins are used:
[0038] A photoinitiator TPO was added to the tetrahydrofuran acrylate monomer, and the mixture was stirred at room temperature for 10 minutes to obtain a homogeneous prepolymer. The prepolymer was then degassed under vacuum for 10 minutes to obtain a bubble-free prepolymer, which was then cured under a UV mercury lamp for 2 minutes to obtain a photocurable resin without boron ester dynamic covalent bonds.
[0039] Table 1. Weight percentage of components in each comparative example and embodiment.
[0040]
[0041] Table 2 shows the tensile and remodeling test results obtained from each comparative example and embodiment.
[0042]
[0043] Table 2 shows the testing standards for elongation at break and toughness, GB / T 1040.2-2006. As can be seen from Table 2, the introduction of dynamic covalent bonds in boron esters can significantly improve the elongation at break and toughness of the material. The self-healing test involved cutting the prepared polymer resin sample into two pieces, placing the fractured surfaces close together in a 25°C constant temperature chamber, and observing the healing of the fractured surfaces after 24 hours. The experiment found that the resin materials prepared in this invention (Examples 1-6) healed their fractured surfaces after 24 hours and adhered tightly together (e.g., ...). Figure 1 Tensile tests were conducted to calculate the ratio of toughness to the original specimen toughness to determine the healing efficiency and assess remodeling ability. However, the resin materials obtained in Comparative Examples 1-3 failed to heal their fracture surfaces after 24 hours, making remodeling difficult.
[0044] Table 3. Fluorescence test results obtained from each comparative example and embodiment.
[0045]
[0046] As can be seen from Table 3, by introducing dynamic boron ester bonds, the present invention enables the obtained photocurable acrylate resin to exhibit blue fluorescence under ultraviolet light (365nm), which can be better applied to the field of anti-counterfeiting technology, and is particularly suitable for the field of 3D printing.
[0047] It should be noted that the above-described technical content of this invention is merely an explanation and clarification to enable those skilled in the art to understand the technical essence of this invention, and therefore is not intended to limit the scope of protection of this invention. The scope of protection of this invention should be determined by the claims. Those skilled in the art should understand that any modifications, equivalent substitutions, and improvements made based on the essential spirit of this invention should be within the scope of protection of this invention.
Claims
1. A method for preparing a photocurable resin containing boron ester dynamic covalent bonds, wherein a boron ester is introduced into the preparation of the photocurable resin, the boron ester being obtained by reacting vinylboric acid with a polyphenol; the resin is an acrylate resin; the vinylboric acid is at least one of 2-vinylphenylboronic acid, 4-vinylphenylboronic acid, and isopropenylboronic acid; the polyphenol is at least one of ellagic acid, tannic acid, quercetin, and tetrahydroxybenzophenone; the boron ester is prepared by the following method: dissolving vinylboric acid in a solvent, adding polyphenol, reacting at room temperature for 18-24 h, and then filtering and purifying; the mass ratio of vinylboric acid to polyphenol is 1:2-4.
2. The preparation method according to claim 1, characterized in that, The purification process involves rotary evaporating the filtered solution at 30-40°C to obtain a solid, washing it with ether, filtering it again, and then rotary evaporating the filtered solution to obtain the borate ester.
3. The preparation method according to any one of claims 1-2, characterized in that, The process includes the following steps: dissolving borate ester in a solvent, adding a photocurable resin monomer, rotary evaporating the mixed solution at 30-40℃ for 3-6 hours to remove the solvent and obtain a homogeneous mixture; adding a photoinitiator and vacuum stirring for 10-30 minutes to obtain a prepolymer; placing the prepolymer into a mold and curing it with UV for 1-3 minutes.
4. The preparation method according to claim 3, characterized in that, The photocurable resin monomer is an acrylate monomer, which is at least one of glycidyl methacrylate, tetrahydrofuran acrylate, isobornyl methacrylate, and isobornyl acrylate.
5. The preparation method according to claim 3, characterized in that, The photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-phenylacetophenone, α,α ， At least one of the following: ethoxyacetophenone, 2-methyl-2-(4-morpholino)-1-[4-(methylthio)phenyl]-1-propanone, 2-dimethylamino-2-benzyl-1-[4-(4-morpholino)phenyl]-1-butanone, ethyl 2,4,6-trimethylbenzoylphosphonate, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and methyl benzoylcarbamate.
6. The preparation method according to claim 3, characterized in that, The mass ratio of the photocurable resin monomer to the borate ester is 3-5:1; the amount of the photoinitiator is 0.5-2% of the total mass of the photocurable resin monomer and the borate ester.
7. The application of the photocurable resin obtained by the preparation method according to any one of claims 1-6 in 3D printing technology.