A core-shell nanoparticle modified epoxy resin and its preparation method
By forming a core-shell structure with a polydopamine shell on the surface of SiO2 nanoparticles, the problem of performance degradation of epoxy resin under ultraviolet radiation was solved, and modified epoxy resin with high strength and excellent ultraviolet shielding performance was prepared.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- UNIV OF SCI & TECH BEIJING
- Filing Date
- 2025-09-05
- Publication Date
- 2026-06-30
AI Technical Summary
Epoxy resins are prone to photo-oxidative degradation under ultraviolet radiation, which leads to deterioration of mechanical properties and chemical stability. Furthermore, inorganic nanoparticles tend to agglomerate in the resin, affecting the strength and toughness of the material.
SiO2 nanoparticles were prepared using the Stöber method, and a polydopamine shell was formed on their surface through molecular self-polymerization to prepare SiO2@PDA core-shell nanoparticles. These nanoparticles were then used as modifiers to blend with epoxy resin to form SiO2@PDA/EP modified epoxy resin.
It improves the flexural strength and impact strength of epoxy resin, significantly enhances its UV shielding performance, and strengthens the overall performance of the material.
Smart Images
Figure CN121045740B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of functional polymer materials technology, and in particular to a core-shell nanoparticle modified epoxy resin and its preparation method. Background Technology
[0002] Epoxy resin (EP) holds an irreplaceable position among thermosetting resins due to its excellent dimensional stability, good processability, and superior overall mechanical properties. However, the high crosslinking density after curing results in relatively poor toughness. Furthermore, in practical applications, prolonged exposure to ultraviolet radiation can trigger photo-oxidative degradation, leading to a sharp deterioration in mechanical properties and chemical stability, severely shortening the service life of epoxy resin-based composites. These drawbacks significantly limit the application of epoxy resins in numerous industrial fields such as aerospace, automotive manufacturing, and construction engineering.
[0003] Adding inorganic nanofillers to epoxy resins is an effective way to improve their mechanical properties. Silica (SiO2) nanoparticles are widely used due to their high hardness, high modulus, and good chemical stability. However, unmodified silica nanoparticles are highly polar and easily form aggregates in epoxy resins, causing stress concentration and leading to a decrease in the material's strength and toughness. Furthermore, pure silica particles primarily rely on physical scattering to shield against ultraviolet radiation, resulting in limited shielding effectiveness and making it difficult to effectively address the UV aging problem of epoxy resins.
[0004] Inspired by mussel adhesive proteins, dopamine (DA) can be tightly coated onto the surface of silica nanoparticles through an oxidation-self-polymerization process, forming a polydopamine (PDA) shell. The abundant phenolic hydroxyl and amino groups in the PDA molecule can form excellent interfacial bonds with the epoxy resin matrix through hydrogen bonds and van der Waals forces. Furthermore, PDA possesses excellent UV absorption capabilities, which can reduce the damaging effects of UV light on the epoxy resin matrix, thereby improving the UV shielding performance of the epoxy resin.
[0005] Currently, there is no existing technology for modifying epoxy resin using core-shell structured particles containing polydopamine and silica. Therefore, this invention attempts to modify epoxy resin in this way to improve its mechanical and UV shielding properties. Summary of the Invention
[0006] The purpose of this invention is to provide a core-shell nanoparticle-modified epoxy resin and its preparation method. The preparation method involves first obtaining uniformly sized core-shell nanoparticles through a two-step process using the Stöber method and molecular self-polymerization. The abundant functional groups in the polydopamine layer enhance the interfacial bonding between the inorganic nanoparticles and the epoxy resin. Finally, the core-shell nanoparticle-modified epoxy resin is prepared using a simple solution blending method. The prepared core-shell nanoparticles improve the flexural strength and impact strength of the modified epoxy resin and significantly enhance its UV shielding performance. It is expected to have significant research value and guiding significance in the preparation of epoxy resins with both high mechanical properties and excellent UV shielding performance.
[0007] To achieve the above objectives, the present invention provides a core-shell nanoparticle modified epoxy resin, which uses core-shell nanoparticles SiO2@PDA to modify the epoxy resin, wherein the SiO2@PDA is SiO2 nanoparticles with polydopamine coated on the surface.
[0008] The present invention also provides a method for preparing the core-shell nanoparticle modified epoxy resin, comprising the following steps:
[0009] S1. SiO2 nanoparticles were prepared using the Stöber method;
[0010] S2. Through molecular self-polymerization reaction, dopamine is polymerized in situ on the surface of SiO2 nanoparticles obtained in step S1 to prepare core-shell nanoparticles SiO2@PDA.
[0011] S3. Using TDE-85 type epoxy resin as the matrix and the core-shell nanoparticles SiO2@PDA obtained in step S2 as the modifier, SiO2@PDA / EP modified epoxy resin was prepared by solution blending.
[0012] Preferably, in step S1, the Stöber method includes the following steps:
[0013] S11. Mix anhydrous ethanol, deionized water and ammonia, then add anhydrous ethanol solution of tetraethyl silicate, and stir the mixture at room temperature for 2-5 hours.
[0014] S12. After the reaction is complete, centrifugation is performed to obtain a precipitate, which is then washed and dried to obtain the SiO2 nanoparticles.
[0015] Preferably, in step S11, the volume ratio of the mixture of anhydrous ethanol, deionized water and ammonia is 50:50:3, the volume ratio of the mixture of tetraethyl silicate and anhydrous ethanol is 10:90, and the volume ratio of the mixture of ammonia and tetraethyl silicate is 3:10.
[0016] Preferably, in step S12, the precipitate is washed sequentially with water and ethanol, and then placed in an oven for vacuum drying for 8-10 hours to obtain the SiO2 nanoparticles.
[0017] Preferably, in step S2, the molecular self-polymerization reaction includes the following steps:
[0018] S21. Dissolve tris(hydroxymethyl)aminomethane (Tris) in deionized water to obtain a 10 mmol / L Tris buffer solution, and adjust the pH of the buffer solution to 8.5 with hydrochloric acid;
[0019] S22. Place the SiO2 particles in the buffer solution obtained in step S21 and disperse them evenly by sonication.
[0020] S23. Add dopamine hydrochloride (DA-HCl) to the buffer solution containing SiO2 obtained in step S22, and stir the reaction at room temperature for 20-30 h.
[0021] S24. After the reaction is complete, centrifugation is performed to obtain a precipitate, which is then washed and dried to obtain the core-shell nanoparticles SiO2@PDA.
[0022] Preferably, in step S23, the mass ratio of dopamine hydrochloride to SiO2 particles is 1:2, and the dopamine hydrochloride is a solid.
[0023] Preferably, in step S24, the precipitate is washed sequentially with water and ethanol, and then placed in an oven for vacuum drying for 8-10 hours to obtain the core-shell nanoparticles SiO2@PDA.
[0024] Preferably, in step S3, the solution blending method includes the following steps:
[0025] S31. Core-shell nanoparticles SiO2@PDA are placed in anhydrous ethanol and dispersed uniformly by ultrasound to obtain a dispersion.
[0026] S32. Add the dispersion obtained in step S31 to TDE-85 epoxy resin and mechanically stir at 70~75 °C for 4-10 h to remove ethanol, and obtain resin mixture.
[0027] S33. Add curing agent 4,4'-diaminodiphenylmethane to the resin mixture obtained in step S32, stir until 4,4'-diaminodiphenylmethane is completely dissolved, pour the resin mixture into a stainless steel mold, and heat and cure.
[0028] S34. After curing, the mixture is cooled to room temperature in the furnace and demolded to obtain the SiO2@PDA / EP modified epoxy resin casting.
[0029] Preferably, in steps S31 and S32, the mass ratio of SiO2@PDA nanoparticles to TDE-85 epoxy resin is (1-7):(93-99). In embodiments of the present invention, the above mass ratios are 1:99, 3:97, 5:95, and 7:93.
[0030] Preferably, in step S33, the amount of 4,4'-diaminodiphenylmethane added is 42.1% of the mass fraction of TDE-85 epoxy resin.
[0031] Preferably, in step S33, the temperature curing parameters are as follows: the stainless steel mold containing the resin is placed in an oven and heated at 100 °C for 1 hour, then heated to 130 °C for 2 hours, then heated to 160 °C for 2 hours, and finally heated to 180 °C for 2 hours. Using a stepped temperature curing method is beneficial for improving the curing efficiency and degree of curing of the epoxy resin.
[0032] Compared with the prior art, the present invention has the following beneficial effects:
[0033] This invention successfully prepared uniformly sized silica (SiO2) nanoparticles and achieved in-situ polymerization of polydopamine (PDA) on the surface of SiO2 nanoparticles, thus preparing SiO2@PDA nanoparticles with a clear core-shell structure. The core-shell nanoparticles prepared in this invention not only exhibit good interfacial bonding with the epoxy resin matrix but also demonstrate a synergistic effect of scattering and absorbing ultraviolet light. The prepared SiO2@PDA / EP modified epoxy resin exhibits superior toughness, higher flexural strength, and excellent ultraviolet shielding performance.
[0034] This invention provides a novel method and approach for the preparation of core-shell structured nanoparticles and the modification of epoxy resins. The tetraethyl silicate, dopamine hydrochloride, and other raw materials used are widely available, inexpensive, and readily available. Furthermore, the entire preparation process is simple, mature, and easy to operate. Attached Figure Description
[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0036] Figure 1 The images shown are scanning electron microscope images of particles from an embodiment. The left image shows silica particles, and the right image shows silica@polydopamine nanoparticles.
[0037] Figure 2Transmission electron microscope image of silica@polydopamine nanoparticles in the example;
[0038] Figure 3 The mechanical properties of the silica@polydopamine nanoparticle-modified epoxy resin prepared in this invention are shown in the figure.
[0039] Figure 4 The UV-Vis absorption spectrum of the silica@polydopamine nanoparticle-modified epoxy resin prepared in this invention is shown. Detailed Implementation
[0040] The objective of this invention is achieved as follows: (1) SiO2 nanoparticles were synthesized using the Stöber method, and their structure and morphology were characterized by scanning electron microscopy. (2) Core-shell nanoparticles SiO2@PDA were prepared by in-situ polymerization of dopamine on the surface of SiO2 nanoparticles through molecular self-polymerization, and their structure and morphology were characterized by scanning electron microscopy and transmission electron microscopy. (3) SiO2@PDA / EP modified epoxy resin was prepared by solution blending using TDE-85 epoxy resin as the matrix and SiO2@PDA nanoparticles as the modifier. The flexural strength, impact strength and ultraviolet shielding performance of the modified epoxy resin were tested by a universal testing machine, an impact testing machine and a UV-Vis spectrophotometer.
[0041] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.
[0042] Example
[0043] 1. Add 125 mL of anhydrous ethanol, 125 mL of deionized water, and 7.5 mL of ammonia to a three-necked flask and stir mechanically at 300 rpm for 10 min. Dissolve 25 mL of tetraethyl orthosilicate in 225 mL of anhydrous ethanol by stirring, and add this solution to the mixture in one step. Stir mechanically at 900 rpm for 5 min, then reduce the stirring speed to 600 rpm and react at room temperature for 3 h. After the reaction is complete, centrifuge to obtain a precipitate, wash with water and ethanol successively until the supernatant is neutral, and dry the precipitate in a vacuum oven at room temperature for 8 h to obtain SiO2 particles.
[0044] 2. Dissolve 0.36 g of tris(hydroxymethyl)aminomethane (Tris) in 300 mL of deionized water to obtain a 10 mmol / L Tris buffer solution, and adjust the pH of the buffer solution to 8.5 with 0.1 mol / L dilute hydrochloric acid. Place 1 g of SiO2 particles obtained in step 1 in the buffer solution and sonicate for 6–8 h. Then, add 0.5 g of dopamine hydrochloride (DA-HCl) to the dispersion system and mechanically stir at 300–350 rpm for 24 h at room temperature. After the reaction is complete, centrifuge to obtain the precipitate, wash successively with water and ethanol until the supernatant is neutral, and place the precipitate in a vacuum oven to dry at room temperature for 8 h to obtain core-shell nanoparticles SiO2@PDA.
[0045] 3. Place 1 g of SiO2@PDA nanoparticles obtained in step 2 into 250 mL of anhydrous ethanol and sonicate for 6-8 h. Add the dispersion to 99 g of TDE-85 epoxy resin and mechanically stir at 250 rpm at 75 °C to remove the ethanol. Then add 4,4'-diaminodiphenylmethane (42.1% by mass of TDE-85 epoxy resin) to the resin mixture and stir rapidly until the 4,4'-diaminodiphenylmethane is completely dissolved. Pour the resin mixture into a stainless steel mold that has been preheated to 70 °C and place it in a vacuum drying oven at 70 °C for a certain period of time until no obvious bubbles are generated on the surface of the mixture. Finally, place the resin in a high-temperature oven and cure it by heating at 100 °C / 1 h + 130 °C / 2 h + 160 °C / 2 h + 180 °C / 2 h. After curing, the sample was cooled to room temperature in the furnace and demolded to obtain a casting of SiO2@PDA / EP modified epoxy resin. The sample was then polished with 80-grit and 1000-grit sandpaper until there were no obvious defects on the surface. Mechanical properties (according to GB / T 2567-2021) and UV shielding performance were then tested.
[0046] The above embodiments yielded three types of core-shell nanoparticle-modified epoxy resins, with the core-shell nanoparticles comprising 1%, 3%, 5%, and 7% of the composite material by mass, respectively. Table 1 shows the raw material ratios and mechanical properties of the core-shell nanoparticle-modified epoxy resins prepared according to this invention. Based on the flexural strength and impact strength data, the optimal addition ratio of silica@polydopamine core-shell nanoparticles is 5%.
[0047] Table 1
[0048]
[0049] Figure 1The images show scanning electron microscope (SEM) images of silica and silica@polydopamine nanoparticles used in the examples. The left image shows that the silica nanoparticles have a regular morphology, smooth surface, and a particle size of approximately 170 nm, and are uniformly dispersed. The right image shows that the silica@polydopamine nanoparticles have a rough surface, an average particle size of approximately 190 nm, and no exposed silica.
[0050] Figure 2 The image shows a transmission electron microscope (TEM) image of the silica@polydopamine nanoparticles from the embodiment. As can be seen from the image, the core diameter of the nanoparticles is approximately 170 nm, and the shell thickness is approximately 10 nm, corresponding to the silica core and polydopamine shell, respectively. The prepared core-shell nanoparticles exhibit a clear core-shell structure and uniform particle size, meeting the expected target. The dispersibility of the core-shell nanoparticles prepared by this invention is significantly better than that of the silica@polybutyl methacrylate core-shell nanoparticles prepared by the emulsion process in Example 2 of prior art 1 (CN201510651105.8).
[0051] Figure 3 The figure shows the mechanical properties of the silica@polydopamine nanoparticle-modified epoxy resin prepared in this invention. As can be seen from the figure, the maximum flexural strength and impact strength of the nanoparticle-modified epoxy resin reached 138.8 MPa and 37.4 kJ / m, respectively. 2 These figures represent increases of 25.7% and 74% respectively compared to pure epoxy resin. In contrast, the optimal embodiment sample prepared by emulsion polymerization in prior art 2 (CN202310047692.4) exhibits a flexural strength of 115.93 MPa and an impact strength of 34.45 kJ / m. 2 The mechanical properties of the samples were significantly lower than those of the samples in the embodiments of the present invention, indicating that the addition of silica@polydopamine nanoparticles can improve the toughness of epoxy resin while improving the strength of epoxy resin.
[0052] Figure 4 The UV-Vis absorption spectrum of the silica@polydopamine nanoparticle-modified epoxy resin prepared in this invention is shown. As can be seen from the figure, the transmittance of pure epoxy resin at 400 nm is 24.9%, and it maintains high transmittance in both the visible and infrared regions. In contrast, the transmittance of the silica@polydopamine nanoparticle-modified epoxy resin in the UV region is almost zero, and its transmittance in the visible and infrared regions is also significantly lower than that of pure epoxy resin.
[0053] 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 variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. Use of core-shell nanoparticle-modified epoxy resin in the field of epoxy resin with both mechanical properties and ultraviolet shielding properties, characterized in that, The core-shell nanoparticle modified epoxy resin is modified by using core-shell nanoparticles SiO2@PDA to modify the epoxy resin. The SiO2@PDA is SiO2 nanoparticles with polydopamine coated on the surface. The preparation method of the core-shell nanoparticle modified epoxy resin includes the following steps: S1. SiO2 nanoparticles were prepared using the Stöber method; S2. Through molecular self-polymerization reaction, dopamine is polymerized in situ on the surface of SiO2 nanoparticles obtained in step S1 to prepare core-shell nanoparticles SiO2@PDA. S3. Using TDE-85 type epoxy resin as the matrix and the core-shell nanoparticles SiO2@PDA obtained in step S2 as the modifier, SiO2@PDA / EP modified epoxy resin was prepared by solution blending. In step S2, the molecular self-polymerization reaction includes the following steps: S21. Dissolve tris(hydroxymethyl)aminomethane (Tris) in deionized water to obtain a 10 mmol / L Tris buffer solution, and adjust the pH of the buffer solution to 8.5 with hydrochloric acid. S22. Place the SiO2 nanoparticles in the buffer solution obtained in step S21 and disperse them uniformly by ultrasound. S23. Add dopamine hydrochloride (DA-HCl) to the buffer solution containing SiO2 nanoparticles obtained in step S22, and stir the reaction at room temperature for 20-30 h. S24. After the reaction is complete, centrifugation is performed to obtain the precipitate, which is then washed and dried to obtain the core-shell nanoparticles SiO2@PDA. In step S3, the solution blending method includes the following steps: S31. Core-shell nanoparticles SiO2@PDA are placed in anhydrous ethanol and dispersed uniformly by ultrasound to obtain a dispersion. S32. Add the dispersion obtained in step S31 to TDE-85 epoxy resin and mechanically stir at 70~75 °C for 4-10 h to remove ethanol, and obtain resin mixture. S33. Add curing agent 4,4'-diaminodiphenylmethane to the resin mixture obtained in step S32, stir until 4,4'-diaminodiphenylmethane is completely dissolved, then pour into a stainless steel mold and heat to cure. S34. After curing, the mixture is cooled to room temperature in the furnace and demolded to obtain the SiO2@PDA / EP modified epoxy resin casting. In steps S31 and S32, the mass ratio of SiO2@PDA nanoparticles to TDE-85 epoxy resin is (1-7):(93-99).
2. Use of the core-shell nanoparticle-modified epoxy resin according to claim 1 in the field of epoxy resins having both mechanical properties and UV shielding properties, characterized in that, In step S1, the Stöber method includes the following steps: S11. Mix anhydrous ethanol, deionized water and ammonia, then add anhydrous ethanol solution of tetraethyl silicate, and stir the mixture at room temperature for 2-5 hours. S12. After the reaction is complete, centrifugation is performed to obtain a precipitate, which is then washed and dried to obtain the SiO2 nanoparticles.
3. Use of the core-shell nanoparticle-modified epoxy resin according to claim 2 in the field of epoxy resins having both mechanical properties and UV shielding properties, characterized in that, In step S11, the volume ratio of anhydrous ethanol, deionized water and ammonia is 50:50:3, the volume ratio of tetraethyl silicate to anhydrous ethanol is 10:90, and the volume ratio of ammonia to tetraethyl silicate is 3:
10.
4. Use of the core-shell nanoparticle-modified epoxy resin according to claim 1 in the field of epoxy resins having both mechanical properties and UV shielding properties, characterized in that, In step S23, the mass ratio of dopamine hydrochloride to SiO2 nanoparticles is 1:
2.
5. The application of the core-shell nanoparticle modified epoxy resin according to claim 1 in the field of epoxy resins possessing both mechanical properties and UV shielding properties, characterized in that, In step S33, the amount of 4,4'-diaminodiphenylmethane added is 42.1% of the mass fraction of TDE-85 epoxy resin.
6. The application of the core-shell nanoparticle modified epoxy resin according to claim 1 in the field of epoxy resins possessing both mechanical properties and UV shielding properties, characterized in that, In step S33, the temperature curing parameters are as follows: place the stainless steel mold containing the resin in an oven and heat it at 100 °C for 1 h, then heat it at 130 °C for 2 h, then heat it at 160 °C for 2 h, and finally heat it at 180 °C for 2 h.