Preparation method and application of light-cured resin added with modified nanosilica

Abstract

The application belongs to but is not limited to the technical field of photocuring resin, and discloses a preparation method and application of photocuring resin added with modified nanometer silicon dioxide; the photocuring resin uses polyethylene glycol and acrylate-200 as polymerization monomers; 2-isopropyl-9H-thioxanthone-9-ketone is used as a light absorber to control light source intensity and light penetration depth; diphenyl (2, 4, 6-trimethylbenzoyl) phosphine oxide is used as a photoinitiator to promote polymerization progress; vinyl modified nanometer silicon dioxide is used as a photocrosslinking agent to form a dense crosslinking network, to enhance crosslinking degree, and at the same time, rigid nanometer material improves mechanical properties of the resin. The application provides a new photocuring resin, the resin uses modified nanometer silicon dioxide as a crosslinking agent in the photocuring resin, which can improve mechanical properties, photocuring speed and printing precision of the resin, and also can maintain good biocompatibility, so as to widen application of the resin in medical treatment and high-precision manufacturing fields.

Description

Technical Field

[0001] This invention belongs to, but is not limited to, the field of photocurable resin technology, and particularly relates to a method for preparing and applying a photocurable resin with modified nano-silica. Background Technology

[0002] With the rapid development of 3D printing technology, photocurable resins have been widely used in various applications such as rapid prototyping, prototype manufacturing, and the medical field. In the 3D printing process, photocurable resins utilize ultraviolet light to initiate a polymerization reaction, thereby rapidly forming a solid structure. In recent years, with the continuous improvement in requirements for printing accuracy, speed, and mechanical properties, the development of novel photocurable resins has become a research hotspot.

[0003] Existing photocurable resins are mostly composed of traditional monomers and initiators. While they can meet certain molding requirements, they still have limitations in terms of mechanical properties, curing speed, and printing accuracy. To address these issues, researchers have attempted to improve resin performance by introducing different fillers or additives. For example, nanomaterials, due to their unique physical and chemical properties, show potential in enhancing the mechanical properties of photocurable resins, improving curing speed, and increasing printing accuracy. In particular, nano-silica (SiO2), as a common filler, has been widely used in resin modification due to its excellent mechanical strength, thermal stability, and compatibility.

[0004] However, traditional nano-silica often suffers from weak interfacial bonding with resin matrices due to the lack of functional groups on its surface, affecting the overall performance of composite materials. To address this issue, researchers have employed surface modification techniques to treat nano-silica, with vinyltriethoxysilane (VTES) modification proving to be an effective method. VTES introduces vinyl groups onto the surface of nano-silica, enhancing not only the chemical bond between the nano-silica and the resin matrix but also improving the efficiency of the photocuring reaction.

[0005] Although some studies have explored resins modified with nano-silica, the following problems still exist: First, existing photocurable resins exhibit uneven curing after the addition of nano-silica, limiting their application in the biomedical field; Second, the surface properties of nano-silica and resin differ, making it difficult for nano-silica covered by silanol bonds to disperse in lipophilic resins. Dispersibility and stability still need further improvement. Surface hydrophobic modification can be used to ensure high precision and efficiency of the resin in the 3D printing process.

[0006] Therefore, there is an urgent need for a new photocurable resin that can improve the mechanical properties, photocuring speed and printing accuracy of the resin by introducing modified nano-silica, while maintaining good biocompatibility, thereby broadening its application in the medical and high-precision manufacturing fields. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a method for functionalizing the surface of silica nanospheres to make them a crosslinking agent and applying them to photocurable resins for 3D printing.

[0008] This invention is achieved as follows: a method for preparing a photocurable resin with modified nano-silica, wherein the photocurable resin uses polyethylene glycol acrylate-200 (PEGDA200) as the polymerizing monomer; 2-isopropyl-9H-thioxanthone-9-one (ITX) as a light absorber to control the light source intensity and light penetration depth; diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO) as a photoinitiator to promote the polymerization process; and synthesized vinyl-modified nano-silica (V-SNP) as a photocrosslinking agent to form a dense crosslinking network, enhancing the degree of crosslinking, while the rigid nanomaterials improve the mechanical properties of the resin;

[0009] The method for preparing the photocurable resin with added modified nano-silica involves weighing the above raw materials, stirring and dissolving them, and then ultrasonically dispersing them.

[0010] Furthermore, the preparation method of the vinyl-modified nano-silica (V-SNP) includes:

[0011] Step 1: Add anhydrous ethanol to a round-bottom flask, the amount of which is 50-300ml, preferably 143ml; at the same time, add 1-10ml of deionized water and 1-20ml of ammonia water (25%), preferably 8ml of ammonia water;

[0012] Step 2: Heat the oil bath to 40-80℃, preferably 65℃. When the temperature reaches 65℃, add 2-8ml of tetraethyl orthosilicate (TEOS), preferably 6ml, and react for 0.5-4h, preferably 2h.

[0013] Step 3: Add vinyltriethoxysilane (VTES) in an amount that is 20%-50% of the volume fraction of tetraethyl orthosilicate (TEOS), preferably 40%, and continue the reaction for 2 hours to obtain vinyl-modified nano silica (V-SNP).

[0014] Furthermore, the amount of ITX added to the photocurable resin is 0.5%-3% of the mass volume fraction of PEGDA200.

[0015] Furthermore, the amount of diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO) added is 0.1%-0.5% of the mass-volume fraction of PEGDA200.

[0016] Furthermore, the amount of vinyl-modified nano-silica (V-SNP) added is 0.5%-5% of the mass volume fraction of PEGDA200.

[0017] Further, stir and dissolve for 2 hours, then ultrasonically disperse for 15 minutes.

[0018] Furthermore, 3D modeling was performed using Solidworks (2019b), the file was exported as an STL file and imported into slicing software, and the sliced ​​file was then imported into a 3D printer for printing.

[0019] Another object of the present invention is to provide a method for preparing a photocurable resin by adding modified nano-silica to a photocurable resin.

[0020] Another object of the present invention is to provide the application of the photocurable resin in 3D printing.

[0021] Furthermore, the 3D printing includes 3D printing mechanical tensile and compression models, 3D printing microfluidic chips, 3D printing biological microneedles, etc.

[0022] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0023] First, this invention uses silica as a crosslinking agent. After surface modification with photocurable groups, it acquires photopolymerization capabilities to participate in the crosslinking network of PEGDA200. It has been proven that the numerous crosslinking sites on the surface of nano-silica promote the photopolymerization process and accelerate the 3D printing speed. Microneedle printing experiments have demonstrated that this resin improves printing accuracy. Due to the addition of rigid nano-silica, the resin's properties are greatly improved. The printed material exhibits significantly enhanced mechanical properties, such as compressive strength and hardness. Most importantly, the strong physical adsorption capacity of the nanomaterial itself, and the fixation effect on toxic small molecule monomers after surface modification, reduce the material's toxicity and expand its direct cellular application scope.

[0024] This invention addresses the problems of insufficient mechanical properties, poor uniform dispersion, and low photopolymerization efficiency in existing photocurable resins by optimizing the preparation conditions of vinyl-modified nano-silica (V-SNP) and the composition ratio of the photocurable resin. Uniform synthesis of nano-silica particles was achieved by controlling the ratio of anhydrous ethanol, deionized water, and ammonia, as well as the reaction temperature (40-80℃). Surface functionalization modification using vinyltriethoxysilane (VTES) improved the photosensitivity of the particles and their dispersibility in the resin matrix. Furthermore, by adding photoinitiators ITX and TPO, along with V-SNP, to PEGDA200 at specific mass-volume fractions, the curing rate and mechanical properties of the resin were optimized, overcoming the technical bottlenecks of slow curing speed, uneven filler distribution, and low molding precision in traditional photocurable resins.

[0025] This invention significantly improves the overall performance of materials by combining nanoscale fillers with photocurable resins. The prepared photocurable resins possess high strength, high toughness, and excellent dimensional stability, meeting the dual requirements of mechanical properties and printing precision in 3D printing. By combining ultrasonic dispersion and a highly efficient initiator system, this invention further improves the uniformity of the resin system and the photopolymerization efficiency, reduces structural defects and errors present in traditional resins, and significantly enhances the reproducibility and application range of printed products, providing technical support for the application of photocurable resins in high-end fields such as precision manufacturing and biomedicine.

[0026] Second, the expected benefits and commercial value of the technical solution of this invention after transformation are as follows:

[0027] The technical solution of this invention provides a photocurable resin with excellent mechanical properties, rapid photocuring capability, good printing accuracy, and no cytotoxicity, offering broad application prospects, particularly in 3D printing, personalized medical devices, and precision manufacturing. This resin not only improves the performance of existing photocurable resins but also, due to its non-cytotoxicity, has potential in the biomedical and bioprinting fields, meeting the high biocompatibility requirements of applications in medical, dental, and orthopedic fields. Once commercialized, it will meet the demands for rapid prototyping and high-precision printing, and is expected to bring significant market value to industries such as biomedicine, 3D printer parts manufacturing, precision model making, and microfluidic biochips, demonstrating high market demand and economic benefits.

[0028] Third, this invention proposes a photocurable resin system based on vinyl-modified nano-silica (V-SNP) for preparation and application, solving the problem of insufficient mechanical properties and stability of existing photocurable resins. By introducing V-SNP into the photocurable resin, the mechanical strength, toughness, and shrinkage control ability during the photocuring process are significantly improved. Simultaneously, the addition ratio of photoinitiators (ITX and TPO) is optimized to ensure high photoreaction efficiency and uniformity of the resin during curing.

[0029] This invention optimizes the preparation process and dosage of V-SNP, clarifies the range and preferred values ​​of reaction conditions (e.g., temperature 65℃, TEOS to VTES ratio of 6 ml and 40%), and achieves an optimal balance between mechanical and photoreactive properties by adjusting the addition ratio of the photocuring system (e.g., ITX 0.5%-3%, TPO 0.1%-0.5%). Furthermore, through appropriate stirring and ultrasonic dispersion steps, uniform distribution of V-SNP in PEGDA200 is ensured, overcoming the problem of easy agglomeration of nanoparticles, thereby improving the transparency and mechanical properties of the resin system.

[0030] Compared to traditional resin systems, the photocurable resin of this invention exhibits higher tensile strength and fracture toughness after the addition of V-SNP, while reducing curing shrinkage and improving the dimensional accuracy and stability of 3D printed structures. By introducing a process combining Solidworks modeling and 3D printing, this invention achieves high-precision printing of complex structures, providing a new solution for the application of functionalized photocurable resins in medical devices, optical components, and high-precision manufacturing. This comprehensive technological innovation fills the gaps in the performance and application areas of traditional photocurable resins, possessing significant industrial value and technological advantages. Attached Figure Description

[0031] Figure 1 This is a flowchart of the preparation method of vinyl-modified nano-silica provided in the embodiments of the present invention;

[0032] Figure 2 These are SEM images of nano-silica before and after modification provided in the embodiments of the present invention;

[0033] Figure 3 This is a schematic diagram illustrating the effect of adding nano-silica before and after modification on resin molding, provided in an embodiment of the present invention.

[0034] Figure 4 This is a toxicity test chart of V-SNP comparative molecular crosslinking agents with different added contents provided in the embodiments of the present invention;

[0035] Figure 5 These are microscopic comparison images of the needle tips before and after modification of the microneedle printing provided in the embodiments of the present invention;

[0036] Figure 6 This is the V-SNP and SNP dispersion diagram provided in the embodiments of the present invention;

[0037] Figure 7 This is a SEM image provided in an embodiment of the present invention;

[0038] Figure 8 This is a tensile stress-strain curve of the material with added V-SNP provided in an embodiment of the present invention;

[0039] Figure 9 This is a printing effect diagram of the resin provided in an embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] This invention provides a method for preparing a photocurable resin with modified nano-silica. The surface of nano-silica is modified with vinyltriethoxysilane to obtain nano-silica with vinyl functional groups, which can then be used as a crosslinking agent in the photocurable resin and can be stably dispersed in lipid-soluble solvents. The photocurable resin uses polyethylene glycol acrylate-200 (PEGDA200) as the polymerizing monomer, 2-isopropyl-9H-thioxanthrol-9-one (ITX) as the light absorber to control the light source intensity and light penetration depth, and diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO) as the photoinitiator to promote the photopolymerization process. The addition of vinyl-modified nano-silica (V-SNP) solves the problems in the prior art, resulting in a novel photocurable resin that effectively improves the overall performance of the resin and expands its direct application in the cellular field.

[0042] The method for preparing the photocurable resin with added modified nano-silica involves thoroughly stirring the above raw materials and then sonicating them.

[0043] like Figure 1 As shown, the preparation method of vinyl-modified nano-silica (V-SNP) provided in this embodiment of the invention includes:

[0044] S101, add anhydrous ethanol to a round-bottom flask, the amount of which is 50-300 ml, preferably 143 ml; at the same time, add 1-10 ml of deionized water and 1-20 ml of ammonia water (25%), preferably 8 ml of ammonia water;

[0045] S102, heat in an oil bath at a temperature of 40-80℃, preferably 65℃. When the temperature reaches 65℃, add 2-8 ml of tetraethyl orthosilicate (TEOS), preferably 6 ml, and react for 0.5-4 h, preferably 2 h.

[0046] S103, add vinyltriethoxysilane (VTES) in an amount of 20%-50% of the volume fraction of tetraethyl orthosilicate (TEOS), preferably 40%, and continue the reaction for 2 hours to obtain vinyl-modified nano silica (V-SNP).

[0047] The amount of ITX added to the photocurable resin provided in this embodiment of the invention is 0.5%-3% of the mass volume fraction of PEGDA200.

[0048] The amount of diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO) added in the embodiments of the present invention is 0.1%-0.5% of the mass volume fraction of PEGDA200.

[0049] The amount of vinyl-modified nano-silica (V-SNP) added in the embodiments of the present invention is 0.5%-5% of the mass volume fraction of PEGDA200.

[0050] The present invention provides a stirring and dissolving process of 2 hours followed by ultrasonic dispersion of 15 minutes.

[0051] This invention provides a method for 3D modeling using Solidworks (2019b), exporting the file to STL format, importing it into slicing software, and then importing the sliced ​​file into a 3D printer for printing.

[0052] This invention provides a method for preparing vinyl-modified nano-silica (V-SNP), achieving the synthesis and surface vinyl functionalization of silica particles via a sol-gel method. First, anhydrous ethanol is used as a solvent, and deionized water and ammonia are added to form an alkaline catalytic system, which is then heated to a target temperature in an oil bath. Tetraethyl orthosilicate (TEOS) undergoes hydrolysis and condensation reactions in this system to form nano-silica particles. Subsequently, vinyltriethoxysilane (VTES) is added to achieve surface vinyl modification of the silica particles, thereby preparing photosensitive nano-silica (V-SNP).

[0053] The main components of the photocurable resin include polyethylene glycol diacrylate (PEGDA200), initiators, and modified fillers. Diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO) and isopropylthioxanthone (ITX) are added to PEGDA200 as initiators at specific mass-volume fractions to enhance its photosensitivity. Vinyl-modified nano-silica (V-SNP) is used as a functional filler, which is thoroughly mixed with PEGDA200 and ultrasonically dispersed to ensure uniform distribution of the filler in the matrix resin, thereby imparting higher mechanical properties and stability to the photocurable resin.

[0054] A 3D structural model was designed using Solidworks (2019b), and the model file was exported as an STL file and then imported into slicing software for processing. The slicing software decomposed the model into a layered structure and generated a printing path file that the 3D printer could recognize. The photocurable resin was cured and stacked layer by layer under the precise control of the 3D printing equipment. PEGDA200 was used as the matrix resin, combined with a photoinitiator and vinyl-modified nano-silica, ensuring that the resin rapidly polymerized and cured under ultraviolet light during the printing process, thus achieving high-precision, high-performance 3D printed products.

[0055] By optimizing the composition ratio of the photocurable resin, the introduction of V-SNP significantly improves the material's mechanical properties, heat resistance, and dimensional stability, while maintaining the excellent printing precision of the photocurable resin. The 3D-printed products have broad application potential in various fields, such as precision manufacturing, biomedical devices, and microfluidic chips. Furthermore, the preparation and printing methods of this invention are simple, and the material properties are controllable, meeting the demands of high-performance 3D printing materials and providing a novel solution for expanding the applications of photocurable resins.

[0056] This invention prepares vinyl-modified nano-silica (V-SNP) via a sol-gel method. First, a mixed solution of anhydrous ethanol, deionized water, and ammonia is heated in an oil bath to maintain solution stability and provide a suitable reaction environment. Then, tetraethyl orthosilicate (TEOS) is added as a silicon source, and primary silicon oxide particles are generated through hydrolysis and condensation reactions. Next, vinyltriethoxysilane (VTES) is added, utilizing its vinyl properties to covalently modify the surface of the generated silicon oxide particles, thereby endowing the nanoparticles with vinyl functional groups and forming uniform and stable V-SNPs.

[0057] The prepared V-SNP nanoparticles were added to PEGDA200-based photocurable resin at a mass-volume fraction of 0.5%-5%. To ensure uniform dispersion of V-SNPs, a process of stirring and dissolving for 2 hours followed by ultrasonic dispersion for 15 minutes was employed. This method promotes the initial dispersion of nanoparticles through mechanical stirring and breaks down agglomerates using ultrasound, resulting in a uniform distribution of V-SNPs within the resin matrix. This further enhances the mechanical properties and optical transparency of the photocurable resin, providing a stable material basis for subsequent 3D printing.

[0058] ITX and TPO were added as a dual photoinitiator system to the UV-curable resin formulation. The amount of ITX added was 0.5%-3% (by weight / volume) of PEGDA200, and TPO was 0.1%-0.5%. TPO, as the main initiator, generates free radicals under UV light, initiating the photopolymerization reaction; ITX, as a photosensitizer, prolongs the lifetime of the free radicals and improves curing efficiency. The synergistic effect of the dual photoinitiator system ensures rapid curing of the resin under light irradiation and controls the curing shrinkage rate, significantly improving the dimensional accuracy and mechanical properties of the 3D printed model.

[0059] The 3D model was designed using Solidworks (2019b) software. After completion, the file was exported as an STL file and imported into slicing software for layering. The sliced ​​data was then transmitted to the 3D printer via an interface. During printing, the prepared photocurable resin was used as the printing material, and the resin was cured layer by layer using a UV light source to form a high-precision three-dimensional structural model. Because the addition of V-SNPs enhances the strength and toughness of the material, this method is not only suitable for manufacturing industrial parts but also for applications in demanding fields such as medical devices and optical components.

[0060] Example 1: Preparation of 3D Printing Photocurable Resin

[0061] Take 143 ml of anhydrous ethanol as solvent, add 8 ml of ammonia (25%) and 3 ml of deionized water, stir and heat to 60°C, add 6 ml of TEOS and react for 2 h, add 1.5 ml of VTES and continue to react for 2 h, filter, wash and dry to obtain V-SNP, weigh 2% V-SNP, 2% ITX and 0.5% TPO, stir and dissolve for 2 h, and ultrasonically disperse for 15 min to obtain resin curing precursor solution.

[0062] Example 2: 3D Printed Mechanical Tension and Compression Model

[0063] The photocurable resin was synthesized and configured using the method described in Example 1. Different concentrations of resin were added according to different V-SNP addition ratios (0.5%, 1%, 2%, 3%, 4%). Mechanical tensile and compression models were modeled in Solidworks (2019b), and the sliced ​​files were exported to the MSLA (mask stereolithography) printer Elegoo Mars4Ultra. The bottom layer exposure was 65s, the layer exposure was 4s, the lift-up speed was 75mm / min, and the lift-up distance was 2mm. The printed models were cured under a 405nm UV post-curing lamp for 8h to obtain a dumbbell-shaped tensile model and a cylindrical compression model with pre-designed structures.

[0064] Example 3: 3D Printing of Microfluidic Chips

[0065] The photocurable resin was synthesized and configured using the method in Example 1. The resin was added according to the optimal ratio. A microfluidic chip model was modeled in Solidworks (2019b). The sliced ​​file was exported to the MSLA printer ElegooMars4Utral. The bottom layer exposure was 65s, the layer exposure was 4s, the lift-off speed was 75mm / min, and the lift-off distance was 2mm. The printed model was cured under a 405nm UV post-curing lamp for 8h to obtain a microfluidic chip model with a pre-designed structure.

[0066] Example 4: 3D Printing of Bio-microneedles

[0067] The photocurable resin was synthesized and prepared using the method in Example 1. The resin was added according to the optimal ratio. A microfluidic chip model was modeled in Solidworks (2019b). The sliced ​​file was exported to the MSLA printer ElegooMars4Utral. The bottom layer exposure was 65s, the layer exposure was 4s, the lift-off speed was 75mm / min, and the lift-off distance was 2mm. The printed model was cured under a 405nm UV post-curing lamp for 8h to obtain a microneedle model with a pre-designed structure.

[0068] I. Specific application areas or related products of this invention.

[0069] 1. 3D printing materials

[0070] The photocurable resin of this invention can be widely used in 3D printing technology, especially for the manufacture of high-precision models. Due to its rapid photocuring capability and excellent mechanical properties, the resin can significantly improve the molding efficiency and product quality of 3D printing. Specific applications include, but are not limited to, high-precision industrial prototyping, rapid prototyping of complex structural parts, and the manufacture of precision assembled components.

[0071] 2. Medical models and personalized medical devices

[0072] Because the photocurable resin of this invention has non-cytotoxic properties, it can be used to print precision models and personalized medical devices in the medical field. For example:

[0073] Customized dentures, dental restoration models, and precise anatomical models for surgical planning

[0074] 3. Bioprinting and Tissue Engineering

[0075] The resin of this invention is suitable for the field of bioprinting due to its non-cytotoxicity and excellent mechanical properties. For example, when printing bioscaffold materials, it can support cell growth and provide the necessary mechanical strength, making it suitable for constructing tissue engineering scaffolds, skin repair materials, and other biomedical applications.

[0076] 4. Manufacturing of high-performance optical components and microstructures

[0077] The high curing precision of this invention makes it suitable for the fabrication of microstructures in the optical field, such as complex lenses, diffractive optical elements, and microfluidic chips. These structures require extremely high surface smoothness and precision, and the photocurable resin of this invention can meet these requirements and improve printing efficiency.

[0078] II. Evidence related to the technical effects obtained by the embodiments of the present invention.

[0079] PEGDA-200 is an oily molecule with numerous double bonds. The presence of these double bonds makes it difficult to disperse SNPs with silanol bonds on the surface. Therefore, V-SNPs with vinyl-modified surfaces theoretically have stronger dispersibility than SNPs. Figure 6 (a) shows the dispersion of the two nanoparticles in water. It can be seen that SNP, due to the presence of silanol bonds, exhibits strong dispersibility in water. In contrast, V-SNP does not dissolve or disperse in water even under strong ultrasonic conditions, indicating a difference in the surface properties of the two nanoparticles. Through modification, a lipid-soluble nanomaterial is obtained, such as... Figure 6 As shown in (b), V-SNPs are uniformly dispersed in PEGDA-200. In 3D printing, the uniformity of the resin material is crucial, determining the overall printing effect. For the resin with added V-SNPs, concentrations of 0.5%, 1%, 2%, 3%, and 4% (w / v) were set to avoid excessive nanosphere deposition. Figure 6 (b) No. 1 is PEGDA200, a transparent oily substance; No. 2 is a resin with added PETTA / PETTA, which is oily and transparent; Nos. 3-7 are resins with added modified nanospheres. It can be observed that with the addition of nanospheres, it exhibits a gradient of milky white properties and good dispersibility.

[0080] First, this invention compared the curing effects of the three materials. Using a mold, under the same mass concentration conditions, and irradiated with a 405nm UV lamp for 30 minutes, the molecular crosslinking agent generated a large amount of heat during polymerization, and without a medium to disperse the heat, it experienced localized overheating. This resulted in numerous cavities in the sample, negatively impacting the stability and molding rate of the printing process. SEM observation further confirmed this. Figure 7 As can be seen, the cross-sectional surface is smooth. However, the addition of SNPs disrupts the cross-linking environment and lacks cross-linking sites, causing the resin to break apart during post-processing. SEM images reveal numerous localized SNP aggregations, explaining its fragility. In contrast, V-SNPs, being lipophilic nanomaterials, exhibit better dispersibility in lipophilic resins. Furthermore, their surface vinyl photocurable groups provide more cross-linking sites. The addition of V-SNPs not only stabilizes the curing process but also provides a heat transfer medium, reducing the thermal effect during curing and preventing excessively vigorous photopolymerization reactions that could create cavities. This can be further demonstrated by examining the cross-sectional SEM images. Figure 2 It was observed that the dispersion in the resin was relatively uniform, with very little agglomeration.

[0081] The tensile stress-strain curve of the material with added V-SNP is as follows: Figure 8 As shown, overall, among different V-SNP contents, the 2% group exhibited relatively good tensile strength, which is related to the large number of crosslinking sites on the surface, approximately 40% higher than that of resin with molecular crosslinking agents. The modified material showed better compressive strength, as nano-silica is a high-rigidity material, thus significantly improving compressive strength. Similar to previous reports, with the addition of nanospheres, especially at 4%, tensile and compressive properties decreased. This is because the addition of a large amount of high-rigidity material disrupted the material's homogeneity, resulting in excessively high or low local stresses, and local aggregation prevented local crosslinking. Therefore, an appropriate concentration is crucial, which is why the addition concentration was controlled below 4%. In addition, the resin with added V-SNPs exhibited better toughness, which also had a positive effect on the printing yield and printing speed. Finally, the hardness of the material was tested, showing a slight increase compared to the control group, with a maximum hardness of 98HA. This is also due to the addition of high-rigidity nano-silica, thus the control group with molecular crosslinking agents had greater hardness. Figure 8 As shown in (i).

[0082] To conduct cytotoxicity experiments on the material, a co-culture method was used. First, a ring-shaped structure suitable for a 96-well plate was 3D printed, then sterilized before a CCK-8 assay. According to previous reports, although the cell viability was within the specified range and around 80%, the material still exhibited slight cytotoxicity. However, for microfluidic micrometer-scale experiments, even slight cytotoxicity can have a significant impact, especially on some environmentally sensitive cells, leading to uncertainty. Figure 4 As shown in (a) and (b), observations were made on 2 and 3 days of cell culture. The cell activity of the material without V-SNP decreased, while the cell activity of the material with nano-crosslinking agent showed a positive growth trend, and the cell survival rate was almost not significantly different from that of the control group, with a maximum cell survival rate of 109%. In addition, this invention observed that the addition of different concentrations of nanomaterials did not change the cell activity. The addition of lower concentrations of nanomaterials had already fixed the free monomers, whether through physical adsorption or free radical polymerization. Therefore, the addition of more non-toxic nanoparticles did not affect the activity.

[0083] Finally, this invention conducted experiments on the printing effect of the resin, testing the minimum printing time for both resins and observing whether the incorporation of V-SNPs with numerous crosslinking sites improved the photopolymerization efficiency. The results showed that only 1.2 seconds of layer exposure was required to complete the printing of the predetermined structure, while the control group required a minimum of 1.8 seconds. For the final molding effect, this invention selected 1.5 seconds for exposure, and the results were as follows... Figure 9 As shown, after the same post-processing, V-SNP has a clearer structural display, while cracks appear on the surface of the control group, which is because the minimum printing time was not reached. This also confirms that incorporating V-SNP can accelerate the printing process and improve the printing effect.

[0084] Meanwhile, to demonstrate its application in biomaterials, and based on previous material characterization data, this invention conducted microneedle printing experiments to assess potential improvements in printing performance. The results showed that the resin with modified nanospheres not only achieved faster printing speeds but also improved printing accuracy, reduced printing instability, and increased the print yield. The microneedles, for example... Figure 9 As shown in (a), the unmodified resin on the left exhibits certain printing defects, with a high failure rate in printing the higher-layer needle tip sections. In contrast, the resin with added V-SNP shows significant stability and can print the higher-layer needle tip sections, as shown in (a). Figure 9 As shown in (b).

[0085] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a photocurable resin with modified nano-silica, characterized in that, The photocurable resin uses polyethylene glycol diacrylate-200 as the polymerizing monomer; 2-isopropyl-9H-thioxanth-9-one as a light absorber to control the light source intensity and light penetration depth; diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide as a photoinitiator to promote the polymerization process; and synthesized vinyl-modified nano-silica as a photocrosslinking agent to form a dense crosslinking network, enhancing the degree of crosslinking, while the rigid nanomaterials improve the mechanical properties of the resin. The method for preparing the photocurable resin with added modified nano-silica involves thoroughly stirring the above raw materials and then sonicating them. The method for preparing the vinyl-modified nano-silica includes: Step 1: Add anhydrous ethanol to a round-bottom flask, the amount of which is 50-300ml; at the same time, add 1-10ml of deionized water and 1-20ml of ammonia water; Step 2: Heat the oil bath to 40-80℃. When the temperature reaches 65℃, add 2-8 ml of tetraethyl orthosilicate and react for 0.5-4 hours. Step 3: Add vinyltriethoxysilane in an amount that is 20%-50% of the volume fraction of tetraethyl orthosilicate, and continue the reaction for 2 hours to obtain vinyl-modified nano-silica. The amount of ITX added to the photocurable resin is 0.5%-3% of the mass volume fraction of polyethylene glycol diacrylate-200; The amount of diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide added is 0.1%-0.5% of the mass-volume fraction of polyethylene glycol diacrylate-200; The amount of vinyl-modified nano-silica added is 0.5%-5% of the mass volume fraction of polyethylene glycol diacrylate-200.

2. The method for preparing the photocurable resin with modified nano-silica as described in claim 1, characterized in that, Stir and dissolve for 2 hours, then ultrasonically disperse for 15 minutes until fully dispersed and uniform.

3. The method for preparing the photocurable resin with modified nano-silica as described in claim 1, characterized in that, Use Solidworks to create 3D models, export the files as STL format, import them into slicing software, and then import the sliced ​​files into a 3D printer for printing.

4. A photocurable resin prepared by a method for preparing a photocurable resin with added modified nano-silica as described in any one of claims 1 to 3.

5. The application of the photocurable resin as described in claim 4 in 3D printing.

6. The application as described in claim 5, characterized in that, The 3D printing includes 3D printing of mechanical tensile and compression models, 3D printing of microfluidic chips, and 3D printing of biological microneedles.

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