Hybrid spiro ortho carbonates monomers with multifunctional photopolymerizable groups, their preparation and use

Abstract

This invention proposes a class of multifunctional photoinitiated expandable monomers, their preparation methods, and applications. The general structural formula is shown in SOC: R1 is selected from hydrogen atoms and alkyl groups with 1-8 carbon atoms; n = 0 or 1; X and X' are linking groups, which are alkyl chains with 1-18 carbon atoms, and one or more of the -CH2- groups can be replaced by -O-, -CO-, -COO-, or OCO-; F and F' are various double-bonded functional groups capable of photoinitiated free radical polymerization, such as acrylates, methacrylates, or vinyl ethers. The expandable monomers prepared by this invention retain the volume expansion properties of spirocyclic orthocarbonates. Furthermore, due to the introduction of photopolymerizable groups, they can be simultaneously copolymerized with commonly used cationic and free radical photopolymerizable monomers, thereby suppressing phase separation caused by differences in polymerization mechanisms between different types of monomers, which can lead to a severe decrease in the strength of the polymerization system. They have great application potential in photoinitiated polymerization applications sensitive to volume shrinkage, and are particularly suitable for optical adhesives, electronic adhesives, 3D printing, and other fields.

Description

Technical Field

[0001] This invention belongs to the field of new materials and organic chemicals technology, specifically relating to a class of multifunctional photoinitiable expansion monomers, their preparation and application, particularly their use in the field of single / two-photon photocurable materials that are sensitive to volume shrinkage and mechanical properties. Background Technology

[0002] Photopolymerization technology is a process that polymerizes liquid photosensitive resin into a solid under light induction. It boasts advantages such as high efficiency, speed, energy saving, economy, and environmental friendliness, and has been widely applied in various fields including adhesives, photocurable coatings and inks, photoresists, 3D printing, three-dimensional microstructure fabrication, and biomedicine. Based on the different photopolymerization active centers, photopolymerization systems are mainly classified into free radical photopolymerization, cationic photopolymerization, and free radical-cationic hybrid photopolymerization.

[0003] Free radical photopolymerization often uses monomers containing double bonds, such as (meth)acrylates and vinyl groups. Its mechanism is a chain polymerization reaction. During the reaction, the van der Waals distance between liquid monomer molecules (about 0.3–0.5 nm) is rapidly transformed into the covalent bond length (about 0.154 nm), resulting in significant volume shrinkage. The shrinkage rate is usually as high as 11%–23%, and it is difficult to avoid.

[0004] Cationic photopolymerization utilizes cationic photoinitiators to generate super-strong protic acids or Lewis acids under light irradiation, which further induce ring-opening or cationic addition polymerization of epoxy groups, vinyl ethers, or oxetanes. Although this system has a low shrinkage rate (approximately 2%–5%), in applications such as dental restorative materials, adhesives, lithography, and coatings, volume shrinkage can still lead to problems such as decreased adhesion, internal porosity, microcracks, and residual stress.

[0005] To balance polymerization rate and material properties, researchers have developed hybrid curing techniques. These typically combine UV-induced rapid polymerization to form an initial cross-linked structure, followed by dark reactions such as thermosetting or moisture curing to further strengthen the three-dimensional network. This two-stage strategy not only improves the structural density and stability of the material but also expands the application potential of photopolymerization technology in high-performance coatings, composite materials, and 3D printing. For example, copolymerizing acrylate monomers with epoxy compounds and expanding monomers can construct interpenetrating network structures with minimal or even slight volume shrinkage, resulting in excellent mechanical properties.

[0006] In recent years, volume changes during photopolymerization have received increasing attention. As intermolecular distances shorten from the van der Waals interaction range to the covalent bond length during polymerization, volume shrinkage becomes a common phenomenon. Significant shrinkage can easily cause microcracks, interfacial debonding, and other problems, impairing the optical, mechanical, and insulating properties of materials. Current main strategies for addressing volume shrinkage include: (1) High-filler composite materials: By introducing a high proportion of fillers that do not participate in the reaction, only the reaction phase shrinks, thereby reducing the overall shrinkage rate. However, fillers can significantly change the mechanical behavior of the material, limiting its application range.

[0007] (2) Prepolymerized oligomers / polymers: The pre-curing stage has completed some shrinkage, which reduces the shrinkage rate of the final photocuring stage. However, this method can only reduce shrinkage and cannot achieve volume expansion.

[0008] (3) Expanding monomers: such as spirocyclic compounds, whose ring-opening polymerization is accompanied by volume expansion, which can effectively offset the resin curing shrinkage. Studies show that the more rings a spirocyclic monomer has, the smaller the volume shrinkage, and even zero shrinkage or net expansion can be achieved. Some reported expanding monomers are shown in the figure below: Among them, spirocyclic orthocarbonates have become a focus of research in various fields due to their large volume expansion rate (5%–20%) resulting from the bicyclic ring-opening reaction during polymerization, and their synthesis technology is relatively mature. Spirocyclic orthocarbonates are considered the most promising class of oxohexaspirates, with applications in areas such as high-strength composites, medical polymers, and high-performance adhesives. However, existing reports on spirocyclic orthocarbonates are mostly suitable for cationic photopolymerization systems, making effective copolymerization with commercially available free radical monomers difficult. This leads to significant phase separation or microstructural defects after curing, resulting in decreased mechanical properties and limiting their wider application. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of existing technologies by providing a class of multifunctional photoinitiable expandable monomers. These monomers, with spirocyclic orthocarbonate as the main molecular structure, contain various double-bond functional groups capable of photoinitiated free radical polymerization. The double bonds are linked to the spirocyclic orthocarbonate via flexible chains with different structures, forming a hybrid expandable monomer containing double bonds. This monomer not only expands through ring-opening polymerization but also better undergoes synchronous photoinitiated copolymerization with commercially available double-bond monomers to form a cross-linked network structure resin. This enhances the expandable effect of the monomer, reduces resin shrinkage, and improves the resin's mechanical properties.

[0010] Another object of the present invention is to provide a method for preparing the above-mentioned type of multifunctional photoinitiable expanding monomer.

[0011] Another object of the present invention is to provide the use of the above-mentioned multifunctional photoinitiable expansion monomers in the field of photocuring, particularly in photocurable products requiring low shrinkage, and in UV-LED photocurable products.

[0012] To achieve the above objectives, the solution of the present invention is: A class of multifunctional photoinitiable expandable monomers, wherein the expandable monomers are composed of radical ring-opening polymerizable functional groups (F, F') linked by linking groups (X, X') and cationic ring-opening spirocyclic orthocarbonates that achieve volume expansion, and their general structural formula is shown in SOC: in, R1 is selected from hydrogen atoms and alkyl groups having 1-8 carbon atoms; n = 0 or 1, meaning that the spirocyclic protocarbonate is a five-membered ring or a six-membered ring; X and X' are linking groups, which can be the same or different, and are alkyl chains with 1 to 18 carbon atoms. One or more of the -CH2- groups can be replaced by -O-, -CO-, -COO- or OCO-, that is, they can be replaced by ether bonds, carbonyl groups or esters with different linkages. F and F' are various double bond functional groups that can be photo-initiated for free radical polymerization. They can be the same or different. Representative group structures are shown below: .

[0013] According to the above general structural formula, the double bonds of the multifunctional photoinitiable expanding monomers described in this invention are mainly acrylates, methacrylates, or vinyl ethers. The core of the molecular design is to connect the double bonds with spirocyclic orthocarbonates using flexible chains containing different structures, such as alkyl chains, ether bonds, and ester bonds, to form hybrid expanding monomers containing double bonds. Specifically, the double bonds participate in free radical polymerization, while the spirocyclic orthocarbonate participates in cationic polymerization. Its advantages are: the spirocyclic orthocarbonate-type multifunctional hybrid monomer contains one or more double bond groups, which can effectively improve the reactivity of the expanding monomer and blend monomers while ensuring low shrinkage; on the other hand, grafting photoinitiable free radical polymerizable groups into the expanding monomer forms an interpenetrating network structure resin, improving the mechanical properties of the cured resin and greatly enhancing its application potential in UV-LED and other photocuring fields.

[0014] Furthermore, some preferred molecular structures of the multifunctional photoinitiable expansion monomers described in this invention are as follows.

[0015] (1) The molecular structure of acrylate containing polymerizable groups and spirocyclic orthocarbonates is shown in the figure below: .

[0016] The main differences in these structures lie in whether the linking group and the spirocyclic orthocarbonate have methyl or ethyl substituents.

[0017] The linking groups are mainly flexible chains of various lengths and ester bonds, such as SOC-1-1 to SOC-1-6; in addition, ether bonds and more ester bonds have been introduced. Of course, the lengths of alkyl chains are also different, as detailed in the remaining structures.

[0018] The preferred substituents on spirocyclic orthocarbonates are methyl and ethyl, which are low-cost raw materials and simple to synthesize.

[0019] (2) The molecular structure of monomers containing methacrylates is shown in the figure below: .

[0020] The linking groups in these structures are similar to those in the acrylate series, and the substituents on the spirocyclic protocarbonate are preferably methyl or ethyl.

[0021] (3) The monomer structures containing vinyl ether photopolymerizable groups are as follows: .

[0022] These molecular structures are similar to the previous two series, except that the photopolymerizable group is replaced with a vinyl ether.

[0023] (4) The molecular structures of monomers with different linking groups or asymmetric structures are as follows: .

[0024] In these structures, the linking group and the spirocyclic protocarbonate structure can also have branched linking groups or be five-membered spirocyclic protocarbonates.

[0025] The linking groups and photopolymerizable groups on both sides of the spirocyclic protocarbonate can also be different, as long as the materials are added during the synthesis. When the linking groups and photopolymerizable groups on both sides of the spirocyclic protocarbonate are different, the reaction yields a mixture of three or more products, depending on the composition and proportion.

[0026] This invention also proposes a strategy for preparing a class of multifunctional, photoinitially polymerizable, expanding monomers: through a two- or three-step esterification reaction, double-bonded groups suitable for free radical or cationic photopolymerization are introduced into the intermediate structure of a spirocyclic orthocarbonate. The specific route mainly involves the preparation of the spirocyclic orthocarbonate structure. This can be achieved by first functionalizing the diol and then ring-linking it with tetraethyl orthocarbonate, or by first forming a diacid with a spirocyclic orthocarbonate structure and then linking it with a haloalkane through esterification. Both methods can efficiently yield the target product. This synthetic route produces less waste, is environmentally friendly, and is suitable for large-scale production. The resulting monomer-based photocurable system exhibits low odor, excellent shrinkage resistance, and outstanding mechanical properties, showing broad application prospects in UV-LED photocuring and other fields.

[0027] Furthermore, the method for preparing a class of multifunctional photoinitiable expanding monomers proposed in this invention includes, in the first preparation method: Step 1.1: Prepare an intermediate with a dihydroxyl structure; Step 1.2: The prepared intermediate is reacted with tetraethyl orthocarbonate to form a spirocyclic orthocarbonate, thereby preparing the target expanded hybrid monomer; wherein: the intermediate added to the reaction in step 1.2 can be one, two or more, and when there are two or more, a mixture is obtained.

[0028] The molecular structure of the intermediate and the synthesis process of the second step reaction are shown below: The reaction for forming spirocyclic orthocarbonate is carried out in toluene solvent, catalyzed by p-toluenesulfonic acid, and then purified by recrystallization or column chromatography. The starting material for the dihydroxy derivative of this reaction can be prepared by esterification.

[0029] Furthermore, in the method for preparing a type of multifunctional photoinitiable expanding monomer proposed in this invention, the second preparation method is as follows: Step (a): 2,2-dihydroxymethylpropionic acid or 2,2-dihydroxymethylbutyric acid and other 2,2-dihydroxymethylalkyl acid compounds are reacted with tetraethyl orthocarbonate to prepare a dicarboxylic acid intermediate containing a spirocyclic orthocarbonate structure. Step (b) involves reacting FY-Br and F'-Y'-Br with Br atom substitution to form an ester with a carboxylic acid to obtain the target expanding hybrid monomer; wherein: Y is the linking group after X is missing an ester bond, Y' is the linking group after X' is missing an ester bond, F and F' can be the same or different, Y and Y' can be the same or different, and when there are two or more types of FY-Br and F'-Y'-Br participating in the reaction, the obtained target expanding hybrid monomer is a mixture.

[0030] The second preparation method involves first preparing a spirocyclic ring with a dicarboxyl group, and then forming an ester. The reaction synthesis process is shown below: The diacid intermediate containing the spirocyclic orthocarbonate structure in step (a) can be prepared by catalysis with p-toluenesulfonic acid in an organic solvent, preferably DMF, toluene or other commonly used organic solvents, and the pure product can be obtained by slurrying with ethyl acetate.

[0031] In step (b), the intermediates FY-Br and F'-Y'-Br containing Br atoms are prepared via esterification. Taking representative molecular structures of intermediates as examples, some general reaction formulas are as follows: Among them, the route represented by reaction (a) mainly involves the reaction of acryloyl chloride or methacryloyl chloride with a haloalcohol; reactions (b), (c), and (d) are alcohol derivatives with various photoinitiable double bond functional groups as described in claim 1, whose hydroxyl groups can be prepared by esterification with brominated alkyl carboxylic acids with different flexible chains. The core structure of this type of compound is to introduce a haloalkane structure, especially a brominated alkane structure, while retaining the functional groups. Finally, the brominated alkane undergoes an esterification reaction with a spirocyclic orthocarbonate diacid using tetramethylguanidine as a catalyst in an organic solvent such as DMF at room temperature. After the reaction, the product is obtained by conventional extraction, washing, drying, and vacuum removal of the solvent.

[0032] In the general reaction formula, m and n represent the number of repeating units, and their values ​​determine the length of the flexible chain in different structures; n is preferably 1, 2, 3, 4; m is preferably 1, 2, 3, 4, 5.

[0033] In the above preparation method, the raw materials used are known compounds in the prior art, which can be commercially available or easily prepared by known synthetic methods.

[0034] The present invention prepares a class of multifunctional photoinitiable expanding monomers that retain the volume expansion property of spirocyclic orthocarbonates. Simultaneously, due to the introduction of photopolymerizable groups, they can achieve simultaneous copolymerization with commonly used cationic and free radical photopolymerizable monomers, thereby suppressing phase separation caused by differences in the polymerization mechanisms of different monomer types, which leads to a severe decrease in the strength of the polymerization system. This has great application potential in photoinitiated polymerization applications sensitive to volume shrinkage, and is particularly suitable for optical adhesives, electronic adhesives, 3D printing, and other fields.

[0035] Furthermore, this invention also proposes the application of the above-described multifunctional photoinitiated expandable monomers as functional monomers in radical-cation hybrid photoinitiated polymerization systems.

[0036] The free radical-cation hybrid photoinitiated polymerization system comprises: (1) At least one or more commercially available radical and cationic photoinitiators that are matched with the corresponding excitation source; (2) At least one or more expandable monomers with double bond groups as shown in SOC, and the amount of SOC in the system is 5 to 70 parts by weight per 100 parts by weight of the total amount of polymerizable components. (3) At least one or more commercially available cationic polymerizable monomers; (4) At least one or more commercially available free radical polymerizable monomers or free radical polymerizable resins; (5) Add small amounts of additives as required, including defoamers, leveling agents, dyes, etc.

[0037] The free radical photoinitiator includes, but is not limited to, free radical photoinitiators 184, 1173, TPO, etc., and can also be any photoinitiator that can initiate free radical polymerization; the cationic photoinitiator includes, but is not limited to, iodonium salts or thiodonium salts, etc., and can also be other photosensitizers.

[0038] The commercially available cationic polymerizable monomer can be various commercially available cyclohexane oxide, oxetane and glycidyl ether cationic polymerizable monomers, or vinyl ether cationic polymerizable monomers. The free radical polymerizable monomer can be a monofunctional, difunctional, trifunctional, or polyfunctional monomer such as acrylates or methacrylates, including but not limited to the molecular structures of TPGDA and TMPTA; the free radical polymerizable resin can be epoxy acrylate, polyurethane acrylate, polyester acrylate, and polyether acrylate, etc.

[0039] This invention further provides an application method for utilizing the aforementioned expandable monomers in photocurable formulations. Specifically, one or more expandable monomers capable of photoinitiated polymerization with multifunctional groups are compounded with commercially available double-bond monomers at different mass ratios. Then, cationic photoinitiators and free radical photoinitiators are added at a content of 1wt%-8wt% of the total mass of the two types of monomers. Various additives, such as defoamers and leveling agents, are then added, with the content adjusted according to performance requirements. The mixture is then thoroughly mixed and ready for use.

[0040] Furthermore, the excitation source for the radiation-cured photoinitiator is selected from one or more of ultraviolet light and visible light.

[0041] Furthermore, the light source for the radiation-curing photoinitiator is selected from one or more of the following: a mercury lamp that emits ultraviolet light or visible light, an LED light source, an LDI light source, and a femtosecond laser.

[0042] Furthermore, in addition to hybrid expandable monomers containing double bonds, double bond monomers, cationic photoinitiators, and free radical photoinitiators, radiation curing applications can also contain any components such as inorganic fillers, organic fillers, colorants, other additives, and solvents, depending on actual needs.

[0043] The colorant is selected from pigments or dyes.

[0044] Other additives include UV absorbers, light stabilizers, flame retardants, etc.

[0045] Further, the specific steps for formula preparation are as follows: (1) Mix raw materials according to the mass ratio of monomer and resin: photoinitiator: additive 100:0.1~10:0~4.5; (2) Stir to fully disperse; (3) Irradiate the polymerization system with light sources of different wavelengths or different light intensities; (4) The polymerization conversion rate can be studied by the change of its characteristic peaks using online infrared methods; wherein: the light source in step (3) can be a mercury lamp (high pressure, medium pressure and low pressure), as well as LEDs with an emission wavelength of 365~465nm, LDI light source, femtosecond laser, etc.

[0046] Furthermore, various photoinitiated radical-cationic photopolymerizable formulations, including radical-cationic hybrid polymerization formulations, are processes well-known to industry practitioners and will not be specifically described. However, formulations containing such multifunctional expandable monomers should be within the scope of protection of this invention.

[0047] Furthermore, this invention also proposes the application of a class of expandable monomers with spirocyclic orthocarbonates as the core and multifunctional groups with different double bond groups that can be photoinitiated for polymerization in formulations requiring low volume shrinkage, such as optical adhesives and single / two-photon 3D printing. The expandable monomers can reduce the structural deformation and performance degradation of products caused by volume shrinkage due to the polymerization of commercial monomers, especially in terms of dimensional stability and mechanical properties.

[0048] The individual representative multifunctional expandable monomer molecular structures conforming to the present invention are as follows (to avoid confusion, based on the differences between photopolymerizable monomers and linking groups, they are simply divided into 4 parts): (1) Monomer series with acrylates as free radical polymerizable structures: (2) Monomer series with methacrylates as free radical polymerizable structures: (3) A series of monomers with vinyl ethers as their free radical and cationic polymerization structures: (4) Monomer series with different functional groups or asymmetric structures: Due to the adoption of the above solution, the beneficial effects of the present invention are: 1. This invention combines double bond groups that can be photopolymerized by free radicals and spirocyclic protocarbonate-type expandable monomers through ester bonds and other linking groups. The raw materials are abundant, inexpensive, and non-toxic. The reaction is simple, efficient, and yields high efficiency, making it easy to scale up production.

[0049] 2. The hybrid expanding monomer containing double bonds prepared by this invention contains double bond groups and can be copolymerized with commercially available acrylate free radical monomers and / or cationic monomers to improve the degree of polymerization and achieve high reactivity, low shrinkage and high strength.

[0050] 3. The hybrid expanding monomer containing double bonds prepared by this invention, when compounded with acrylate monomers, forms a pure polyether (ester) structure after polymerization, which has good biocompatibility. The prepared resin is green, environmentally friendly, and non-toxic.

[0051] Legend Figure 1 The image shown is of SOC-1-1 in Example 1. 1 1H NMR (DMSO-d6) spectrum.

[0052] Figure 2 The image shows SOC-1-2 in Example 2. 1 1H NMR (DMSO-d6) spectrum.

[0053] Figure 3 The image shown is of SOC-1-6 in Example 3. 1 1H NMR (DMSO-d6) spectrum.

[0054] Figure 4 The image shown is of SOC-1-8 in Example 4. 1 1H NMR (DMSO-d6) spectrum.

[0055] Figure 5 The image shown is of SOC-1-10 in Example 5. 1 1H NMR (DMSO-d6) spectrum.

[0056] Figure 6 The image shown is of SOC-1-12 in Example 6. 1 1H NMR (DMSO-d6) spectrum.

[0057] Figure 7 The image shown is of SOC-2-2 in Example 7. 1 1H NMR (DMSO-d6) spectrum.

[0058] Figure 8 The image shows SOC-2-7 in Example 8. 1 1H NMR (DMSO-d6) spectrum.

[0059] Figure 9 The image shows SOC-3-8 in Example 9. 1 1H NMR (DMSO-d6) spectrum.

[0060] Figure 10 The image shown is of SOC-3-9 in Example 10. 1 1H NMR (DMSO-d6) spectrum.

[0061] Figure 11 The figure shown is the photopolymerization curve of the formulation involving SOC-1-2 via RT-FTIR double bond groups (light intensity: 100mW / cm). 2 ).

[0062] Figure 12 The figure shows the ring-opening polymerization curve of the SOC-1-2-involved formulation via RT-FTIR of epoxy groups (light intensity: 100 mW / cm). 2 ).

[0063] Figure 13 The figure shows the ring-opening polymerization curve of the SOC-1-2-involved formulation via RT-FTIR oxobutyric groups.

[0064] Figure 14 The figure shows the ring-opening polymerization curve of the SOC-1-2-involved formulation via RT-FTIR spirocyclic groups. Detailed Implementation

[0065] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0066] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0067] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0068] Example 1: Preparation of SOC-1-1 (1) Preparation of SOC-1-1-1 1 eq of bromoethanol (100 g) and 1.2 eq of triethylamine (97.2 g) were dissolved in 600 mL of dichloromethane (DCM), and the reaction system was cooled to 0 °C. Under ice bath and temperature control, 1.5 equivalents of acryloyl chloride (108.6 g) were slowly added dropwise, with the reaction temperature maintained below 0 °C throughout to reduce acryloyl chloride volatilization and suppress side reactions. After the addition was complete, the system was brought to room temperature and the reaction was continued with stirring. Thin-layer chromatography (TLC) was used to monitor the reaction progress. After the reaction was complete, the product was washed with water, extracted, and dried anhydrous to obtain a crude product. 500 ppm of hydroquinone was added to the crude product as a polymerization inhibitor, followed by vacuum distillation. The fraction was collected at 40–50 °C to obtain a colorless, transparent liquid product with a yield of 76%.

[0069] 1 H NMR (400 MHz, DMSO- d 6) δ 6.37 (d, J = 17.4 Hz, 1H), 6.20 (dd, J = 17.2,10.3 Hzz, 1H), 5.99 (d, J = 12.0 Hz, 1H), 4.43 (t, J = 5.6 Hz, 2H), 3.73 – 3.69(m, 2H). (2) Preparation of SOC-1-1-2 0.1 mol (2 eq) of 2,2-dimethylolpropionic acid and 0.05 mol (1.0 eq) of tetraethyl orthocarbonate were placed in a three-necked flask, and 250 mL of toluene was added as a solvent, along with 0.02 g of p-toluenesulfonic acid as a catalyst. The reaction system was heated to 110 °C and subjected to transesterification with stirring. The reaction process was monitored using TLC. After the reaction was complete, the toluene was evaporated to dryness, the mixture was slurried with ethyl acetate, filtered, and dried to obtain the target product. The yield was 79%.

[0070] 1 H NMR (400 MHz, DMSO-d6) δ 12.75 (s, 2H), 4.14 (d, J = 11.1 Hz, 4H), 3.69 (dd, J = 17.9, 11.2 Hz, 4H), 1.06 (s, 6H). (3) Preparation of SOC-1-1 The prepared SOC-1-1-1 (0.1 mol, 17.9 g, 2 eq) and SOC-1-1-2 (13.8 g, 1 eq) were added to a three-necked flask, and 100 mL of DMF was added as solvent. The reaction was carried out with tetramethylguanidine (TMG, 0.2 mol) as catalyst and stirred at room temperature. The reaction was monitored by TLC. After the reaction was complete, the product was extracted with dilute hydrochloric acid, sodium bicarbonate solution, saturated sodium chloride solution, and deionized water, respectively. The product was dried over anhydrous sodium sulfate, and after evaporating the solvent, it was dried under vacuum to obtain a white solid product. The yield was 85%.

[0071] 1 H NMR (400 MHz, DMSO-d6) δ 6.34 (dd, J = 17.3, 1.6 Hz, 2H), 6.18 (dd, J =17.2, 10.3 Hz, 2H), 5.97 (dd, J = 10.3, 1.6 Hz, 2H), 4.35 (s, 8H), 4.17 – 4.13(m, 4H), 3.73 (dd, J = 18.6, 11.3 Hz, 4H), 1.06 (s, 6H). Example 2: Preparation of SOC-1-2 (1) Preparation of SOC-1-2-2 (dihydroxybutyrate derivative) Further, in the synthesis of the target product, 1 eq of DMBA (50 g) and 1 eq of tetramethylguanidine (TMG, 62.3 g) were dissolved in 300 mL of DMF and reacted at room temperature with stirring for 30 min. Subsequently, 1.01 eq of 2-bromoethyl acrylate (SOC-1-2-1 (same as SOC-1-1-1), 97.6 g) and 20 mg of hydroquinone were slowly added to the system as polymerization inhibitors. After the addition was complete, the reaction temperature was raised to 50 °C and the reaction was continuously stirred for about 5 h. After the reaction was completed, the high-boiling-point solvent DMF was first completely removed by vacuum distillation. The crude product was dissolved in dichloromethane and further purified by column chromatography (petroleum ether: ethyl acetate = 1:1) to obtain a colorless and transparent liquid intermediate product (SOC-1-2-2) with a yield of 89%.

[0072] 1 H NMR (400 MHz, DMSO- d 6) δ 6.34 (dd, J= 17.2, 1.6 Hz, 1H), 6.16 (dd, J =17.2, 10.3 Hz, 1H), 5.96 (dd, J = 10.4, 1.6 Hz, 1H), 4.53 (t, J = 5.4 Hz, 2H),4.32 – 4.28 (m, 2H), 4.27 – 4.23 (m, 2H), 3.51 (qd, J = 10.5, 5.4 Hz, 4H), 1.42(q, J = 7.5 Hz, 2H), 0.73 (t, J = 7.5 Hz, 3H). (3) Preparation of SOC-1-2 Two eq of SOC-1-2-2 (30 g) and one eq of tetraethyl orthocarbonate (11.7 g) were dissolved in 500 mL of toluene, with 6 mg of hydroquinone and 0.3 g of p-toluenesulfonic acid added as catalysts. The system was stirred at 110 °C for approximately 3 h, and the reaction progress was monitored by TLC to confirm that the starting materials were essentially completely converted. After the reaction was complete, the toluene solvent was removed by vacuum distillation, and the crude product was further purified by column chromatography to obtain a colorless, transparent liquid product (SOC-1-2) with a separation yield of 74%.

[0073] 1 H NMR (400 MHz, DMSO- d 6) δ 6.34 (dd, J = 17.2, 1.6 Hz, 2H), 6.16 (dd, J =17.2, 10.4 Hz, 2H), 5.97 (dd, J = 10.4, 1.6 Hz, 2H), 4.38 – 4.32 (m, 8H), 4.16(d, J = 11.7 Hz, 4H), 3.76 (dd, J = 21.2, 11.8 Hz, 4H), 1.49 (q, J = 7.6 Hz, 4H), 0.73 (t, J = 7.6 Hz, 6H). Example 3: Preparation of SOC-1-6 1 eq of DMBA (50 g) and 1 eq of tetramethylguanidine (TMG) were dissolved in 300 mL of DMF and reacted at room temperature with stirring for 30 min to fully deprotonate the DMBA carboxyl group, forming the corresponding carboxylate intermediate. Then, 1.01 eq of 6-bromohexyl acrylate (SOC-1-6-1, 1 eq) and 20 mg of hydroquinone were slowly added to the system. After the addition was complete, the reaction temperature was raised to 50 °C, and the reaction was stirred continuously for approximately 5 h. After the reaction was complete, the high-boiling-point solvent DMF was first completely removed by vacuum distillation. The resulting crude product was dissolved in dichloromethane (DCM) and further separated by column chromatography. A colorless, transparent liquid product (SOC-1-6-2) was finally obtained, with a separation yield of 79%.

[0074] Then, 2 eq of SOC-1-6-2 (30 g) and 1 eq of tetraethyl orthocarbonate were dissolved in 500 mL of toluene, and 6 mg of hydroquinone and 0.3 g of [unspecified ingredient] were added. p -TsOH (1 wt%) was used as a catalyst. The system was stirred at 110 °C for about 3 h, and the reaction progress was monitored by TLC to confirm that the starting material was basically completely converted. After the reaction was completed, the toluene solvent was removed by vacuum distillation, and the crude product was further purified by column chromatography.

[0075] 1 H NMR (400 MHz, DMSO- d 6) δ 6.29 (d, J = 17.2 Hz, 2H), 6.20 (dd, J = 17.2, 10.4 Hz, 2H), 5.94 (d, J = 10.4 Hz, 2H), 4.15 (d, J =11.3 Hz, 4H), 4.09 (t, J =7.4 Hz, 8H), 3.74 (dd, J = 21.2, 11.8 Hz, 4H), 1.60 (m, 8H), 1.48 (q, J = 7.6 Hz, 4 H), 1.34 (m, 8H), 0.74 (t, J = 7.6 Hz, 6H). Example 4: Preparation of SOC-1-8 (1) Preparation of SOC-1-8-1 First, 1 mol of bromoacetic acid and an equimolar amount of 2-hydroxyethyl acrylate were dissolved in 500 mL of dichloromethane, and 5 g of DMAP (0.01 eq) was added as a catalyst. Under ice-water bath cooling and stirring conditions, a DCC solution dissolved in dichloromethane (1 mol of DCC dissolved in 100 mL of DCM) was slowly added dropwise, controlling the dropping rate to keep the reaction system temperature below 30°C. A large amount of precipitate gradually formed during the reaction. The reaction progress was monitored by TLC. After the reaction was complete, the solid precipitate was removed by filtration. The resulting filtrate was washed successively with a weak acid solution, a weak base solution, and water. Finally, the organic phase was dried and vacuum distilled, collecting the fraction at 120°C as the product, with a yield of 95%.

[0076] NMR data: 1 H NMR (400 MHz, DMSO-d6) δ 6.36 (dt, J = 17.3, 2.0 Hz, 1H), 6.19 (dd, J = 17.2, 10.3 Hz, 1H), 5.98 (dt, J = 10.3, 2.0 Hz, 1H), 4.40 – 4.31(m, 4H), 4.18 (s, 2H). (2) Preparation of SOC-1-8-2 2,2-Dihydroxymethylbutyric acid (0.1 mol, 14.8 g, 2 eq) and tetraethyl orthoformate (0.05 mol, 1.0 eq) were placed in a three-necked flask, and 300 mL of toluene was added as a solvent, along with p-toluenesulfonic acid (0.02 g) as a catalyst. The reaction system was heated to 110 °C and subjected to transesterification with stirring. The reaction process was monitored using TLC. After completion, the toluene was evaporated to dryness, and the product was slurried with ethyl acetate to obtain a white powder product in 86% yield.

[0077] 1 H NMR (400 MHz, DMSO-d6) δ 12.81 (s, 2H), 4.15 (dd, J = 11.1 Hz, 4H), 3.74 (dd, J = 17.9, 11.2 Hz, 4H), 1.48 (q, J = 8.0 Hz, 4H), 0.77 (t, , J = 8.0 Hz, 6H). (3) Preparation of SOC-1-8 The SOC-1-8-2 synthesized in the second step (0.1 mol, 1 eq) was added to a three-necked flask, along with 150 mL of DMF as solvent. 0.2 mol of tetramethylguanidine was added dropwise under ice-water bath conditions. After the addition was complete, the system was cooled to room temperature and reacted for 30 min under these conditions. Then, 0.2 mol of SOC-1-8-1 prepared in the first step was added, and the reaction was carried out at room temperature, monitored by TLC. After the reaction was complete, the product was washed with 1N hydrochloric acid, 1N sodium hydroxide solution, sodium chloride solution, and deionized water, respectively. The organic phase was dried over anhydrous sodium sulfate, the solvent was evaporated, and the product was dried under vacuum for 24 hours to obtain a colorless, viscous liquid product. The yield was 90%.

[0078] NMR data: 1 H NMR (400 MHz, DMSO) δ 6.35 (dd, J = 17.2, 1.6 Hz, 2H), 6.19(dd, J = 17.2, 10.3 Hz, 2H), 5.98 (dd, J = 10.4, 1.6 Hz, 2H), 4.79 (s, 3H), 4.37– 4.29 (m, 8H), 4.19 (d, J = 11.4 Hz, 4H), 3.81 (dd, J = 18.6, 11.5 Hz, 4H), 1.58(q, J = 7.5 Hz, 4H), 0.82 (t, J = 7.5 Hz, 6H). Example 5: Preparation of SOC-1-10 (1) Preparation of SOC-1-10-1 First, 4-bromobutyric acid and an equimolar amount of 2-hydroxyethyl acrylate were dissolved in a suitable amount of dichloromethane, and 0.01 eq of DMAP was added as a catalyst. Under ice-water bath cooling and stirring conditions, a DCC solution dissolved in dichloromethane was slowly added dropwise, controlling the dropping rate to keep the reaction system temperature below 30 °C. A large amount of precipitate gradually formed during the reaction. The reaction progress was monitored by TLC. After the reaction was complete, the solid precipitate was removed by filtration. The resulting filtrate was washed successively with a weak acid solution, a weak base solution, and water. The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation to obtain the product, which required no further purification and had a yield of 93%.

[0079] NMR data: 1H NMR (400 MHz, DMSO) δ 6.35 (dt, J = 17.2, 1.7 Hz, 1H), 6.19(ddd, J = 17.2, 10.3, 1.7 Hz, 1H), 5.98 (dt, J = 10.3, 1.8 Hz, 1H), 4.35 – 4.26(m, 4H), 3.55 (td, J = 6.7, 1.7 Hz, 2H), 2.48 (t, J = 7.4 Hz, 2H), 2.05 (p, J = 6.9Hz, 2H). (2) Preparation of SOC-1-10 The SOC-1-8-2 (0.1 mol, 1 eq) synthesized in the second step of Example 4 was added to a three-necked flask, along with 150 mL of DMF as solvent. 0.2 mol of tetramethylguanidine was added dropwise under ice-water bath conditions. After the addition was complete, the system was cooled to room temperature and reacted for 30 min under these conditions. Then, 0.2 mol of SOC-1-10-1 prepared in the first step was added, and the reaction was carried out at room temperature. The reaction was monitored by TLC. The processing method was the same as in Example 4. The yield was 92%.

[0080] NMR data: 1 H NMR (400 MHz, DMSO-d6) δ 6.34 (dd, J = 17.3, 1.6 Hz, 2H), 6.18 (dd, J = 17.2, 10.3 Hz, 2H), 5.97 (dd, J = 10.3, 1.6 Hz, 2H), 4.33 – 4.25(m, 8H), 4.19 – 4.08 (m, 8H), 3.76 (dd, J = 27.4, 11.4 Hz, 4H), 2.41 (t, J = 7.3Hz, 4H), 1.85 (p, J = 6.8 Hz, 4H), 1.48 (q, J = 7.5 Hz, 4H), 0.73 (t, J = 7.5 Hz, 6H). Example 6: Preparation of SOC-1-12 (1) Preparation of SOC-1-12-1 First, bromoacetic acid and an equimolar amount of 4-hydroxybutyl acrylate were dissolved in an appropriate amount of dichloromethane, and 0.01 eq of DMAP was added as a catalyst. Under ice-water bath cooling and stirring conditions, a DCC solution dissolved in dichloromethane was slowly added dropwise, controlling the dropping rate to keep the reaction system temperature below 30 °C. A large amount of precipitate gradually formed during the reaction. The reaction progress was monitored by TLC. After the reaction was complete, the solid precipitate was removed by filtration. The resulting filtrate was washed sequentially with a weak acid solution, a weak base solution, and water. The treatment was the same as in Example 4, with a yield of 92%.

[0081] NMR data: 1 H NMR (400 MHz, CDCl3) δ 6.41 (dd, J = 17.4, 1.6 Hz, 1H), 6.13(ddd, J = 17.3, 10.4, 1.3 Hz, 1H), 5.84 (dd, J = 10.4, 1.5 Hz, 1H), 4.21 (qd, J =5.6, 3.1 Hz, 4H), 3.85 (d, J = 1.3 Hz, 2H), 1.82 – 1.76 (m, 4H). (2) Preparation of SOC-1-12 The specific experimental procedure is described in Example 4. The product is a viscous, colorless liquid. The yield was 94%.

[0082] NMR data: 1 H NMR (400 MHz, DMSO-d6) δ 6.31 (dd, J = 17.3, 1.6 Hz, 2H), 6.18 (dd, J = 17.2, 10.3 Hz, 2H), 5.96 (dd, J = 10.3, 1.6 Hz, 2H), 4.77 (s, 4H), 4.22 (d, 4H), 4.14 (m, 8H), 3.82 (m, 4H), 1.66 (m, 8H), 1.58 (q, J = 7.5 Hz, 4H), 0.83 (t, J = 7.5 Hz, 6H). Example 7: Preparation of SOC-2-2 (1) Preparation of SOC-2-2-1 First, 62.5 g of bromoethanol (0.5 mol, 1 eq) and 50.5 g of triethylamine (0.6 mol, 1.2 eq) were dissolved in 500 mL of dichloromethane (DCM), and the reaction system was cooled to 0 °C. Under continuous ice bath and temperature control, 52.5 g of methacrylamide chloride (0.75 mol, 1.5 eq) was slowly added dropwise, maintaining the reaction temperature below 0 °C throughout to effectively suppress the volatilization of the acyl chloride and the occurrence of side reactions. After the addition was complete, the reaction system was moved to room temperature and the reaction was stirred. The reaction progress was monitored in real time by TLC. After the reaction was completed, the product was washed with water, extracted, and dried anhydrous to obtain the crude product. The pure product could then be prepared by vacuum distillation.

[0083] (2) Preparation of SOC-2-2 The SOC-1-8-2 (0.15 mol, 1 eq) synthesized in step 2 of Example 4 was added to a three-necked flask, along with 80 g of DMSO as solvent. 34.6 g of tetramethylguanidine (0.3 mol) was added dropwise under ice-water bath conditions. After the addition was complete, the system was cooled to room temperature and reacted for 30 min under these conditions. Then, 58.0 g of SOC-2-2-1 (0.3 mol) and 0.1 g of p-methoxyphenol were added, and the reaction was carried out at room temperature, monitored by TLC. After the reaction was complete, the reaction solution was washed with water, extracted with ethyl acetate, and then washed successively with 1N hydrochloric acid, 1N sodium hydroxide, saturated sodium chloride aqueous solution, and deionized water. The solvent was evaporated under vacuum to obtain the product. The yield was 95%.

[0084] NMR data: 1 H NMR (400 MHz, DMSO) δ 6.03 (s, 2H), 5.70 (q, J = 1.8 Hz, 2H), 4.33 (ddt, J = 14.9, 7.9, 3.4 Hz, 8H), 4.16 (d, J = 11.3 Hz, 4H), 3.76 (dd, J = 20.5, 11.4 Hz, 4H), 1.87 (s, 6H), 1.49 (q, J = 7.6 Hz, 4H), 0.73 (t, J = 7.5Hz, 6H). Example 8: Preparation of SOC-2-7 (1) Preparation of SOC-2-7-1 First, 69.7 g of bromoacetic acid was added to a three-necked flask. Then, 65.1 g of hydroxyethyl methacrylate was dissolved in 500 mL of dichloromethane, and 0.1 g of hydroquinone was added as a polymerization inhibitor, along with 1.71 g of DMAP as a catalyst (0.01 eq). Under ice-water bath cooling and stirring conditions, a DCC solution dissolved in dichloromethane (103 g of DCC dissolved in 300 mL of DCM) was slowly added dropwise, controlling the dropping rate to keep the reaction system temperature below 30 °C. A large amount of precipitate gradually formed during the reaction. The reaction progress was monitored by TLC. After the reaction was complete, the solid precipitate was removed by filtration. The resulting filtrate was washed successively with a weak acid solution, a weak base solution, and water. After removing the solvent under vacuum, the product was obtained. The yield was 95%.

[0085] NMR data: 1 H NMR (400 MHz, CDCl3) δ 6.16 – 6.13 (m, 1H), 5.61 (p, J = 1.6Hz, 1H), 4.46 – 4.37 (m, 4H), 3.87 (s, 2H), 1.95 (t, J = 1.2 Hz, 3H). (2) Preparation of SOC-2-7 The SOC-1-1-2 (0.1 mol, 1 eq) synthesized in the second step of Example 1 was added to a three-necked flask, along with 150 mL of DMF as solvent. 0.2 mol of tetramethylguanidine was added dropwise under ice-water bath conditions. After the addition was complete, the system was cooled to room temperature and reacted for 30 min under these conditions. Then, 0.2 mol of SOC-2-7-1 prepared in the first step was added, and the reaction was carried out at room temperature. The reaction was monitored by TLC. The rest of the reaction was the same as in Example 1, with a yield of 94%.

[0086] NMR data: 1 H NMR (400 MHz, DMSO) δ 6.04 (t, J = 1.4 Hz, 2H), 5.71 (h, J =1.5 Hz, 2H), 4.79 (s, 4H), 4.39 – 4.29 (m, 8H), 4.19 (dq, J= 11.3, 1.5 Hz, 4H), 3.78 (dd, J = 16.0, 11.4 Hz, 4H), 1.88 (t, J = 1.3 Hz, 6H), 1.13 (s, 6H). Example 9: Preparation of SOC-3-8 (1) Preparation of SOC-3-8-1 First, 0.1 mol of 4-bromobutyric acid and an equimolar amount of 0.1 mol of 2-hydroxyethyl vinyl ether were dissolved in a suitable amount of dichloromethane, and 0.01 eq of DMAP (0.001 mol) was added as a catalyst. Under ice-water bath cooling and stirring conditions, a DCC solution dissolved in dichloromethane was slowly added dropwise, controlling the dropping rate to keep the reaction system temperature below 30 °C. A large amount of precipitate gradually formed during the reaction. The reaction progress was monitored by TLC. After the reaction was complete, the solid precipitate was removed by vacuum filtration. The resulting filtrate was washed successively with a weak acid solution, a weak base solution, and water. After drying with anhydrous sodium sulfate, the inorganic salts were filtered off, the solvent was evaporated, and the product was obtained by vacuum drying, with a yield of 89%.

[0087] NMR data: 1 H NMR (400 MHz, CDCl3) δ 6.49 (ddt, J = 14.4, 6.8, 1.7 Hz,1H), 4.34 (ddt, J = 4.7, 3.3, 1.7 Hz, 2H), 4.21 (dq, J = 14.4, 2.0 Hz, 1H), 4.06(dq, J = 6.7, 2.0 Hz, 1H), 3.90 (ddt, J = 4.6, 3.0, 1.5 Hz, 2H), 3.51 – 3.44 (m,2H), 2.60 – 2.51 (m, 2H), 2.24 – 2.13 (m, 2H). (2) Preparation of SOC-3-8 The SOC-1-8-2 (0.1 mol, 1 eq) synthesized in step 2 of Example 4 was added to a three-necked flask, along with 150 mL of DMF as solvent. 0.2 mol of tetramethylguanidine was added dropwise under ice-water bath conditions. After the addition was complete, the system was cooled to room temperature and reacted for 30 min under these conditions. Then, 0.2 mol of SOC-3-8-1 prepared in step 1 was added, and the reaction was carried out at room temperature, monitored by TLC. After the reaction, the treatment was the same as in the previous example. The yield was 85%.

[0088] NMR data: 1 H NMR (400 MHz, DMSO) δ 6.51 (dd, J = 14.3, 6.8 Hz, 2H), 4.25– 4.18 (m, 8H), 4.12 (t, J = 6.3 Hz, 4H), 4.01 (dd, J = 6.8, 2.0 Hz, 2H), 3.89 –3.85 (m, 4H), 3.77 (dd, J = 27.6, 11.4 Hz, 4H), 2.43 (t, J = 7.4 Hz, 4H), 1.87(q, J = 6.8 Hz, 4H), 1.48 (q, J = 7.6 Hz, 4H), 0.74 (t, J = 7.5 Hz, 6H). Example 10: Preparation of SOC-3-9 (1) Preparation of SOC-3-9-1 First, bromoacetic acid and an equimolar amount of 4-hydroxybutylvinyl ether were dissolved in 100 mL of dichloromethane, and 0.01 eq of DMAP was added as a catalyst. Under ice-water bath cooling and stirring conditions, a DCC solution dissolved in dichloromethane was slowly added dropwise, controlling the dropping rate to keep the reaction system temperature below 30 °C. A large amount of precipitate gradually formed during the reaction. The reaction progress was monitored by TLC. After the reaction was complete, the solid precipitate was removed by filtration. The resulting filtrate was washed sequentially with a weak acid solution, a weak base solution, and water. The treatment was the same as in the previous example, with a yield of 85%.

[0089] NMR data: 1 H NMR (400 MHz, CDCl3) δ 6.46 (dd, J= 14.3, 6.8 Hz, 1H), 4.25– 4.18 (m, 3H), 4.16 (d, J = 2.0 Hz, 1H), 4.00 (dd, J = 6.8, 2.0 Hz, 1H), 3.84(s, 2H), 3.72 (t, J = 5.7 Hz, 2H), 1.78 (td, J = 7.2, 3.8 Hz, 4H). (2) Preparation of SOC-3-9 The SOC-1-8-2 (0.1 mol, 1 eq) synthesized in step 2 of Example 4 was added to a three-necked flask, along with 150 mL of DMF as solvent. 0.2 mol of tetramethylguanidine was added dropwise under ice-water bath conditions. After the addition was complete, the system was cooled to room temperature and reacted for 30 min under these conditions. Then, 0.2 mol of SOC-3-9-1 prepared in step 1 was added, and the reaction was carried out at room temperature, monitored by TLC. After the reaction, the treatment was the same as in the previous example. The yield was 88%.

[0090] NMR data: 1 H NMR (400 MHz, DMSO) δ 6.33 (dd, J = 17.3, 1.6 Hz, 2H), 6.18(dd, J = 17.3, 10.3 Hz, 2H), 5.95 (dd, J = 10.3, 1.6 Hz, 2H), 4.77 (s, 4H), 4.20(d, J = 11.4 Hz, 4H), 4.13 (q, J = 3.1 Hz, 8H), 3.82 (dd, J = 18.8, 11.4 Hz, 4H), 1.66 (p, J = 3.2 Hz, 8H), 1.59 (q, J = 7.5 Hz, 4H), 0.83 (t, J = 7.5 Hz, 6H). <Experiment> Experiments were conducted using some of the products from the above embodiments. First, the products from the embodiments were compounded with commercial monomers, photoinitiators, and additives. The structures and abbreviations that may be used in the formulation are shown in the figure below: <Experiment 1> The formulation design, online infrared experiment, volume shrinkage experiment and tensile property test of the expanded monomer SOC-1-2 prepared in Example 1.

[0091] (1) Formulation design The weight of the expanding monomer and the commercially available compound monomer was divided into 100 parts, and five samples were prepared according to the SOC-1-2 content. BYK-307 and BYK-055 were used as the leveling agent and defoamer, respectively. The percentage content of each component in the formulation is shown in the table below: Table 1. Five formulations designed in Experiment 1 (2) Online infrared experiment The prepared solution was coated onto a PE film to form a coating of approximately 20 μm. Using a 365 nm LED light source as the excitation source, the film was placed in an online infrared fixture, and online infrared spectroscopy polymerization testing was performed with the light source turned on. The conversion rate was calculated based on the area of ​​the characteristic peaks of different functional groups.

[0092] The results show that the curing speed of the formulation containing the expanded monomer of the present invention and the commercial epoxy monomer is significantly improved, and the degree of polymerization is also improved to a certain extent. Specific photopolymerization kinetic curves for different functional groups are shown below. Figure 11-14 As shown in Table 2, the conversion rates of various functional groups in different formulations are as follows.

[0093] Table 2. Conversion rates of various functional groups under photoinitiated polymerization in the five formulations designed in Experiment 1. (3) Tensile properties test of the photocured products of the five formulations designed in Experiment 1 The five formulas from Experiment 1 were added to a dumbbell-shaped silicone mold, with a thickness controlled at 1 mm. The mold was then cured in a UV curing machine using a 365nm light source at 100mW / cm². 2 The sample was cured at high power for 300 seconds, and then placed in a 90°C oven for post-curing for 12 hours to obtain a tensile sample. Tensile properties were then tested using a universal testing machine, and the average value of five parallel samples was taken. We found that adding the expanding monomer prepared in this invention significantly improved the tensile strength and toughness of the sample.

[0094] (4) Test of volume shrinkage rate of the photocured products of the 5 formulations designed in Experiment 1 The volumes of the five formulations before and after photocuring were measured using a densitometer, and the expansion rates were calculated. The specific test results are shown in Table 3. The results show that increasing the proportion of expanding monomers is beneficial to reducing the expansion rate of the samples after curing. However, due to formulation issues, the solubility cannot be further improved, and the shrinkage generated during photocuring cannot be completely eliminated.

[0095] Table 3. Shrinkage test results of the five formulations in Experiment 1 before and after photocuring. <Experiment 2> The formulation design and volume shrinkage experiment of the expanded monomer SOC-1-7 prepared in the examples. (1) Formulation design The weight of the expanded monomer and the commercially available compound monomer was divided into 100 parts, and five samples were prepared according to the SOC-1-7 content. The content of each component in the formulation is shown in the table below: Table 4. Five formulations designed in Experiment 2 (2) Volume shrinkage test of the photocured products of the 5 formulations designed in Experiment 2 The volumes of the five formulations before and after photocuring were measured using a densitometer, and the expansion rates were calculated. The specific test results are shown in Table 5. The results show that increasing the proportion of expanding monomers is beneficial to reducing the expansion rate of the cured samples. However, due to formulation issues, the solubility cannot be further improved, and the shrinkage generated during photocuring cannot be completely eliminated.

[0096] Table 5. Shrinkage test results of the five formulations in Experiment 2 before and after photocuring. Experiment 3 The formulation design, photopolymerization kinetics test, volume shrinkage experiment and mechanical property test of the expanded monomer SOC-1-10 prepared in Example 5.

[0097] (1) Formulation design The weight of the expanded monomer and the commercially available compound monomer was divided into 100 parts, and five samples were prepared according to the SOC-1-10 content. The content of each component in the formulation is shown in the table below: Table 6. Five formulations designed in Experiment 3 (2) Online infrared experiment The prepared solution was coated onto a PE film to form a coating of approximately 20 μm. Using a 365 nm LED light source as the excitation source, the film was placed in an online infrared fixture, the light source was turned on, and the irradiation time was 200 s for online infrared spectroscopy polymerization testing. The conversion rate was calculated based on the area of ​​the characteristic peaks of different functional groups. After completion, the coating was heat-treated in a 60°C oven for 20 min, and the infrared data was tested again to further improve the functional group conversion rate by utilizing the photothermal synergistic effect.

[0098] The results show that the curing speed of the formulation containing the expanded monomer of the present invention combined with the commercial epoxy monomer is significantly improved, and the degree of polymerization is also improved to a certain extent. The double bond conversion rate of the system after adding the expanded monomer is significantly improved, the conversion rate of spirocyclic rings gradually increases with the amount of expanded monomer added, and the oxobutane and epoxy groups maintain efficient conversion throughout. The conversion rates of various functional groups in different formulations are shown in Table 7.

[0099] Table 7. Experiment <3> The conversion rates of various functional groups under photo-initiated polymerization in the five formulations designed in the middle. (3) Photo-DSC test The experiment was conducted using photo-DSC. <3> Kinetic analysis was performed on the photopolymerization systems involving five formulations designed in the study. 0.9–1.1 mg of each formulation was added to an aluminum crucible, placed on a sample stage, and incubated at 100 mW·cm⁻¹. - Under 365 nm LED light source illumination, the curing kinetic parameters of different components were obtained by real-time monitoring of polymerization heat flow changes, as shown in Table 8. The results show that all formulations exhibit good photoinitiation activity, and the maximum heat flow and total heat release decrease with the increase of the proportion of expanding monomers, demonstrating the regulatory role of the spirocyclic orthocarbonate structure as an endothermic unit on the polymerization thermal behavior.

[0100] Table 8. Experiment <3> Photo-DSC test data of 5 formulations designed in the middle (4) Volume shrinkage test of the photocured products of the five formulations designed in Experiment 3 The five formulations from Experiment 3 were added to a rectangular silicone mold. The mold was preheated to 90°C on a heating table and held for 10 minutes. Then, it was cured in a UV curing machine using a 365nm light source at 10mW / cm². 2 Curing at 100mW / cm for 200s, then at 100mW / cm 2The samples were cured at a power of 200 s. The volumes of the five formulations before and after photocuring were measured using a densitometer, and the expansion rates were calculated. The specific test results are shown in Table 9. The results show that increasing the proportion of expanding monomers is beneficial to reducing the expansion rate of the cured samples. However, due to formulation issues, the solubility cannot be further improved, and the shrinkage generated during photocuring cannot be completely eliminated.

[0101] Table 9. Shrinkage test results of the five formulations in Experiment 3 before and after photocuring. (5) Tensile properties test of the photocured products of the five formulations designed in Experiment 3 The five formulas from Experiment 3 were added to a dumbbell-shaped silicone mold, with a thickness controlled at 1 mm. The mold was then cured in a UV curing machine using a 365nm light source at 10mW / cm². 2 Curing at 100mW / cm for 200s, then at 100mW / cm 2 The light-cured sample was cured for 200 seconds, and then placed in a 60 °C oven for 12 hours to obtain a tensile sample. Tensile properties were then tested using a universal testing machine (tensile rate 5 mm / min), and the average value of five parallel samples was taken. Specific test results are shown in Table 10. We found that adding the expanded monomer prepared in this invention significantly improved the tensile strength and toughness of the sample. However, when the expanded monomer content reached 20%, the tensile strength and toughness decreased slightly. This is because the polyether carbonate segments formed by spiro-ring opening polymerization have excellent flexibility, and the introduction of these flexible segments inevitably reduces the overall rigidity of the material.

[0102] Table 10. Tensile test results of photocurable products of SOC-1-10 hybrid system (6) Hardness test of the photocured products of the five formulations designed in Experiment 3 The five formulations from Experiment 3 were added to a rectangular silicone mold and cured in a UV curing machine using a 365nm light source at 10mW / cm². 2 Curing at 100mW / cm for 200s, then at 100mW / cm 2 The photocuring time was 200 seconds. The hardness of the photocured products was measured at different times after curing using a Shore hardness tester. The specific test results are shown in Table 11. The results indicate that after the photocuring reaction is complete, the Shore hardness of the photocured products of different formulations gradually increases and tends to stabilize with increasing post-curing time. Ultimately, the hardness of all formulations remained above 90 HD.

[0103] Table 11. Shore hardness test results of SOC-1-10 hybrid system photocured products <Experiment 4> Formulation design and volume shrinkage experiment of the expanded monomer SOC-1-12 prepared in Example 6 (1) Formulation design The weight of the expanded monomer and the commercially available compound monomer was divided into 100 parts, and five samples were prepared according to the SOC-1-12 content. The content of each component in the formulation is shown in the table below: Table 12. Five formulations designed in Experiment 4 (2) Test of volume shrinkage rate of the photocured products of the 5 formulations designed in Experiment 4 The volumes of the five formulations before and after photocuring were measured using a densitometer, and the expansion rates were calculated. The specific test results are shown in Table 13. The results show that increasing the proportion of expanding monomers is beneficial to reducing the expansion rate of the cured samples. However, due to formulation issues, the solubility cannot be further improved, and the shrinkage generated during photocuring cannot be completely eliminated.

[0104] Table 13. Shrinkage test results of the five formulations in Experiment 4 before and after photocuring. The above description of the embodiments is intended to enable those skilled in the art to understand and use the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments. Improvements and modifications made by those skilled in the art based on the principles of the present invention, without departing from the scope of the invention, should be within the protection scope of the present invention.

Claims

1. A class of multifunctional, photoinitially polymerizable, expanding monomers, characterized in that: The expanded monomer is composed of a radically ring-opening polymerizable functional group (F, F') linked by a linking group (X, X') and a cationic ring-opening spirocyclic orthocarbonate that achieves volume expansion, as shown in the general structural formula of SOC: in, R1 is selected from hydrogen atoms and alkyl groups having 1-8 carbon atoms; n = 0 or 1, meaning that the spirocyclic protocarbonate is a five-membered ring or a six-membered ring; X and X' are linking groups, which can be the same or different, and are alkyl chains with 1 to 18 carbon atoms. One or more of the -CH2- groups can be replaced by -O-, -CO-, -COO- or OCO-, that is, they can be replaced by ether bonds, carbonyl groups or esters with different linkages. F and F' are various double bond functional groups that can be photo-initiated for free radical polymerization. They can be the same or different and can be selected from one of the following structural formulas: 。 2. The expandable monomer capable of photoinitiated polymerization of multiple functional groups as described in claim 1, characterized in that: Its molecular structure is as follows: (1) Contains acrylate monomers: ； (2) Contains methacrylate monomers: ； (3) Contains vinyl ether monomers: ； (4) Monomers with different functional groups or asymmetric structures: 。 3. The method for preparing a type of multifunctional photoinitiable expanding monomer as described in claim 1, characterized in that, This preparation method involves a two- or three-step esterification reaction to introduce double-bonded groups suitable for free radical or cationic photopolymerization into the intermediate structure of a spirocyclic orthocarbonate, thereby preparing the target expanded hybrid monomer. The preparation method includes two core routes to choose from: Core route (1): Step 1.1: Prepare an intermediate with a dihydroxyl structure; Step 1.2: The intermediate with the prepared dihydroxyl structure is reacted with tetraethyl orthocarbonate to form a spirocyclic orthocarbonate, thereby preparing the target expanded hybrid monomer; wherein: the intermediate with the dihydroxyl structure added to the reaction in step 1.2 can be one, two or more, and when two or more intermediates are added to the reaction in step 1.2 at the same time, a mixture is obtained; Core route (2): Step 2.1: 2,2-Dihydroxymethylalkyl acid compounds are first reacted with tetraethyl orthocarbonate to prepare a diacid intermediate containing a spirocyclic orthocarbonate structure; Step 2.2: FY-Br and F'-Y'-Br with Br atom substitution react with carboxylic acid to form esters, obtaining the target expanding hybrid monomer; wherein: Y is the linking group after X missing one ester bond, Y' is the linking group after X' missing one ester bond, F and F' can be the same or different, Y and Y' can be the same or different, when there are two or more types of FY-Br and F'-Y'-Br participating in the reaction, the obtained target expanding hybrid monomer is a mixture.

4. The method for preparing a type of multifunctional photoinitiable expanding monomer as described in claim 3, characterized in that: In the core route (1), the reaction to form spirocyclic orthocarbonate is carried out in toluene solvent, prepared by catalysis with p-toluenesulfonic acid, and then purified by recrystallization or column chromatography.

5. The method for preparing a type of multifunctional photoinitiable expanding monomer as described in claim 3, characterized in that: In the core route (2), the diacid intermediate containing the spirocyclic orthocarbonate structure in step 2.1 is prepared by catalysis with p-toluenesulfonic acid in an organic solvent, and the pure product can be obtained by slurrying with ethyl acetate.

6. The method for preparing a type of multifunctional photoinitiable expanding monomer as described in claim 3, characterized in that: In the core route (2), the intermediates FY-Br and F'-Y'-Br with Br atoms in step 2.2 are prepared by esterification reaction, using tetramethylguanidine as catalyst, in organic solvents such as DMF at room temperature. After the reaction is completed, the product is obtained by conventional extraction, washing, drying, and vacuum removal of solvent.

7. The application of the multifunctional photoinitiable expanding monomer of claim 1 as a functional monomer in a radical-cation hybrid photoinitiated polymerization system.

8. The application as described in claim 7, characterized in that, The radical-cation hybrid photoinitiated polymerization system comprises: (1) At least one or more commercially available radical and cationic photoinitiators that are matched with the corresponding excitation source; (2) At least one or more expandable monomers with double bond groups as shown in SOC, and the amount of SOC in the system is 5 to 70 parts by weight per 100 parts by weight of the total amount of polymerizable components. (3) At least one or more commercially available cationic polymerizable monomers; (4) At least one or more commercially available free radical polymerizable monomers or free radical polymerizable resins; (5) Small amounts of additives, etc., should be added as required, including but not limited to defoamers, leveling agents, and dyes.

9. The application of the multifunctional photoinitiable expansion monomer of claim 1 in photocurable formulations.

10. The application of the multifunctional photoinitiable expanding monomer of claim 1 in formulations requiring low volume shrinkage, such as optical adhesives and single / two-photon 3D printing.

Images