Hyperbranched polymer grafted silicon carbide composite filler as well as preparation method and application thereof

Abstract

The invention discloses a hyperbranched polymer grafted silicon carbide composite filler and a preparation method and application thereof, and belongs to the technical field of polymer composites, the composite filler comprises SiC, HBP and nano functional particles; the preparation method comprises the following steps: grafting on the surface of hydroxylated SiC to form an HBP intermediate layer to obtain SiC-g-HBP, and loading nano functional particles on the surface of the HBP layer by utilizing abundant amino functional groups on the surface of the HBP to form a composite filler; the composite filler is dispersed in a resin matrix, and the composite material is obtained through curing molding. According to the invention, a three-layer core-shell structure is constructed, and uniform loading of nano functional particles is realized by utilizing the molecular glue effect of HBP; all the components have a synergistic effect, so that the composite material has excellent temperature resistance, corrosion resistance, wear resistance and flame retardance at the same time, the interface bonding strength is high, and the filler is uniformly dispersed.

Description

Technical Field

[0001] This application belongs to the field of polymer composite materials technology, and in particular relates to a hyperbranched polymer-grafted silicon carbide composite filler, its preparation method and application. Background Technology

[0002] Silicon carbide (SiC), as an important inorganic functional filler, is widely used in the preparation of high-temperature resistant and wear-resistant polymer-based composites due to its excellent thermal stability, high hardness, and good chemical inertness. However, there is a natural incompatibility between SiC fillers and epoxy resins. SiC surfaces are hydrophilic, while epoxy resins are hydrophobic, leading to easy agglomeration of the filler in the matrix, weak interfacial bonding, and even the formation of microscopic defects that become channels for corrosive media penetration, thus reducing the overall performance of the composite material. Therefore, improving the interfacial compatibility between SiC fillers and the polymer matrix is ​​crucial for enhancing the performance of composite materials. To address these issues, researchers have explored various SiC surface modification methods, mainly including silane coupling agent treatment and surface grafting with polymers. Among these, hyperbranched polymers... Hyperbranched polymers (HBP) grafting modification of SiC has attracted widespread attention in recent years. Hyperbranched polymers have unique advantages such as three-dimensional spherical structure, abundant terminal functional groups, low viscosity, and high reactivity, and can construct a dense organic interface phase on the SiC surface. In the prior art, a variety of preparation methods and applications of SiC-HBP composite fillers have been disclosed.

[0003] Patent CN104829944A employs a three-step method to graft hyperbranched polyarylamide onto the surface of nano-SiC whiskers: first, SiC is hydroxylated to obtain SiC-OH, then silanization is performed to introduce reaction sites (SiC-APS), and finally, hyperbranched polymer is grafted through solution polymerization to obtain SiC-HBP composite filler, which is then used to modify polypropylene composite materials, effectively improving the dispersibility and interfacial bonding strength of the filler. The paper "Enhancing Interfacial Properties of Epoxy Coatings via Hyperbranched Modification of SiC Fillers: Experimental and Simulation Insights" (Chemical Engineering Journal, Volume 511, 1 May 2025, 161841) discloses the application of hyperbranched modified SiC fillers in epoxy coatings. A one-step method was used to synthesize hyperbranched polymers containing hydroxyl and carboxyl groups, which were then grafted onto the SiC surface via dehydration condensation to obtain HBP-SiC composite fillers. Results showed that the carboxyl and ether bonds on the HBP-SiC surface formed covalent and hydrogen bonds with the epoxy resin, significantly improving the compatibility between the filler and the resin and greatly enhancing hydrophilicity. When HBP-SiC filler was added to the epoxy coating at a concentration of 30%, the wear mass loss of the coating decreased to 0.0124. g, and still maintains a high impedance modulus after high temperature and high pressure corrosion test, showing excellent wear resistance and corrosion resistance; molecular dynamics simulation further confirmed that the introduction of HBP-SiC reduced the free volume fraction of the coating and the diffusion coefficient of the corrosive medium, forming a denser interface structure.

[0004] However, existing SiC-HBP technology still has the following shortcomings: Single function and difficulty in achieving multiple properties: Existing SiC-HBP mainly addresses the issues of filler dispersion and interfacial compatibility. Its modification effect is concentrated on improving mechanical properties and basic corrosion resistance, making it difficult to simultaneously endow composite materials with multiple functions such as wear resistance, flame retardancy, and high-temperature resistance. However, in practical applications, composite materials often need to meet multiple requirements at the same time. Existing technologies usually adopt the method of blending multiple functional fillers, but the compatibility between different fillers is poor and interfacial defects are prone to occur. For example, adding flame retardants may deteriorate mechanical properties, and adding hard wear-resistant fillers may reduce corrosion resistance. Therefore, how to further construct composite materials with multiple functions based on SiC-HBP, and ensure that the functions synergistically enhance rather than restrict each other, has become an urgent technical problem to be solved in this field.

[0005] This application has found that after hyperbranched polymers are grafted onto the surface of SiC, their abundant terminal functional groups (such as amino, carboxyl, and hydroxyl groups) can not only crosslink with the resin matrix, but also serve as a reaction platform to further load other functional components, thus fully utilizing the multifunctional potential of the interfacial phase. Summary of the Invention

[0006] In response to the aforementioned technical problems, this application provides a hyperbranched polymer-grafted silicon carbide composite filler, its preparation method, and its application. Based on the existing SiC-HBP, a three-layer core-shell structure of SiC core-HBP interface phase-functional nanoparticle layer is constructed to achieve synergistic enhancement of multiple functions.

[0007] To achieve the above objectives, the technical solution adopted in this application is: to provide a hyperbranched polymer-grafted silicon carbide composite filler, comprising a silicon carbide core, an amino-terminated hyperbranched polymer intermediate layer grafted onto the surface of the silicon carbide core, and a functional nanoparticle layer loaded on the hyperbranched polymer intermediate layer.

[0008] In one embodiment, The amino content of the terminal amino hyperbranched polymer is 2.5-4.5 mmol / g, and the molecular weight is 2000-4000. The terminal amino hyperbranched polymer is preferably hyperbranched polyamide-amine or hyperbranched polyethyleneimine. The functional nanoparticles are one of nano-silica, nano-alumina or nano-zirconia.

[0009] This application also provides a method for preparing hyperbranched polymer-grafted silicon carbide composite fillers, specifically including the following steps: (a) Silicon carbide surface treatment: Silicon carbide powder is added to an alkaline solution for treatment to obtain hydroxylated silicon carbide; (II) Construction of the interfacial phase: Hydroxylated silicon carbide was ultrasonically stirred in a mixed solvent to obtain a dispersion; the terminal amino hyperbranched polymer was dissolved and added dropwise to the dispersion to react and obtain SiC-g-HBP slurry; (III) Construction of functional nanoparticle layer: The functional nanoparticles are ultrasonically dispersed to obtain a suspension. The suspension is added dropwise to SiC-g-HBP slurry and reacted with active amino and hydroxyl groups. After the reaction is completed, the functional composite filler is obtained through post-treatment.

[0010] In one embodiment, Step (1) The surface treatment temperature is 70-90 ℃ and the time is 4 h; the particle size of silicon carbide powder is 3-5 μm and the concentration of alkaline solution is 10 wt%; the mass ratio of silicon carbide powder to alkaline solution is 1:3-5.

[0011] In one embodiment, Step (ii) The mixed solvent consists of water and anhydrous ethanol, with a volume ratio of water to anhydrous ethanol of 1:1-4.

[0012] In one embodiment, Step (ii) The mass ratio of hydroxylated silicon carbide to mixed solvent is 1:9-11, and the amount of terminal amino hyperbranched polymer added is 5-15% of the mass of hydroxylated silicon carbide; the pH of the reaction system is 5.0-6.0, the reaction temperature is 65-85 ℃, and the time is 6 h.

[0013] In one embodiment, Step (3): The mass ratio of functional nanoparticles to hydroxylated silicon carbide is 0.15-0.25:1; the reaction temperature is 65-85 ℃ and the reaction time is 4 h.

[0014] In one embodiment, The specific steps of post-treatment in step (3) are as follows: After the reaction is completed, the precipitate is washed three times with deionized water and ethanol alternately, dried at 60 ℃ for 24 h, and then ground into powder.

[0015] This application also provides an application of hyperbranched polymer-grafted silicon carbide composite filler, in which the composite filler is used to prepare epoxy resin composite materials. The composite material includes: epoxy resin, hyperbranched polymer-grafted silicon carbide composite filler, and curing agent. In the composite filler, the amino-terminated hyperbranched polymer intermediate layer undergoes a chemical cross-linking reaction with the epoxy resin through its active amino groups. The curing agent is polyamide, diaminodiphenylmethane, or m-phenylenediamine.

[0016] In one embodiment, By weight, 100 parts epoxy resin, 20-40 parts hyperbranched polymer-grafted silicon carbide composite filler, and 60-70 parts curing agent.

[0017] This application provides a hyperbranched polymer-grafted silicon carbide composite filler, its preparation method, and its application. Compared with the prior art, it has the following advantages: 1. This application employs a two-step process of "grafting followed by loading" to load functional nanoparticles onto a hyperbranched polymer interfacial phase through chemical coordination, forming a SiC core-HBP intermediate layer-functional nanoparticle shell structure. This structure significantly enhances the interfacial bonding strength. The hyperbranched polymer interfacial phase contains active amino groups that can undergo chemical cross-linking reactions. The functional nanoparticles are not freely dispersed in the matrix, but are firmly loaded through the active amino functional groups of HBP, indicating that the interfacial bonding force is much stronger than physical adsorption, making the composite material more compact and demonstrating good interfacial compatibility. 2. By constructing a core-shell structure, a synergistic improvement of multiple properties such as temperature resistance, corrosion resistance, wear resistance, and flame retardancy is achieved: (1) Temperature resistance: SiC provides a thermal stability framework, HBP forms a flexible cross-linked network, and functional nanoparticles serve as rigid nodes, jointly constructing a temperature-resistant anchoring structure. The HBP interface phase forms a molecular bridge between SiC and resin, restricting the movement of epoxy segments at high temperatures; the functional nanoparticles loaded on HBP further increase the rigidity and physical cross-linking points of the interface region; (2) Corrosion resistance: The electrochemical impedance modulus of the composite material in this application reaches 6.8×10 9 Ω·cm², which is nearly one order of magnitude higher than Comparative Example 1 and more than three times higher than Comparative Example 2; this significant improvement is due to the HBP layer filling the microscopic defects on the SiC surface and blocking the direct penetration channels of the corrosive medium; the loaded functional nanoparticles form a dense inorganic shell, which further extends the diffusion path of the corrosive medium; the maze effect and barrier effect are superimposed: the organic network of HBP and the inorganic shell of functional nanoparticles form an organic-inorganic composite barrier, which has a much better barrier effect against water, oxygen and chloride ions than a single organic layer or simple physical mixture; (3) wear resistance: the wear mass loss of the composite material of this application is reduced by 45% compared with Comparative Example 1 and by 32% compared with Comparative Example 2. %, its anti-wear mechanism is manifested as follows: the SiC core bears the main load and provides basic hardness, the HBP flexible layer buffers the impact stress during the friction process and prevents hard particles from falling off; the loaded functional nanoparticles form a ball bearing effect and transfer film on the friction surface, reducing the friction coefficient; the hard-flexible-hard three-layer structure works together, during the friction process, the outer functional nanoparticles bear the friction first, the HBP layer absorbs the impact energy, and the SiC core provides support, the three work together to make the wear resistance far exceed that of a simple mixed system; (4) Flame retardant performance: the limiting oxygen index of the composite material of this application reaches 29.5%, reaching the flame retardant level, the HBP is rich in nitrogen, which promotes the expansion and foaming of epoxy matrix at high temperature to form an expanded carbon layer, the functional nanoparticles migrate to the material surface at high temperature, and combine with the expanded carbon layer to form a ceramic-carbon hybrid protective layer, which significantly enhances the heat insulation and oxygen insulation effect; nitrogen-inorganic synergistic flame retardancy forms a dense and stable composite protective layer, and the flame retardant effect far exceeds that of a single mechanism; 3. The process of this invention is simple, without harsh high temperature and high pressure, and without complicated purification. It can be completed in a conventional reactor. The raw materials are readily available and easy to industrialize. It can be widely used in high-performance protective coatings and structural components in aerospace, automotive industry, marine engineering, electronic packaging and other fields. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The X-ray photoelectron energy Al 2p spectrum of nano-alumina; Figure 2 The X-ray photoelectron energy Al 2p spectrum of the SiC-g-HBP@Al2O3 functional composite filler in Example 1 is shown. Figure 3 The X-ray photoelectron energy N 1s spectrum of SiC-g-HBP in Example 1; Figure 4 The image shows the N 1s X-ray photoelectron energy spectrum of the SiC-g-HBP@Al2O3 functional composite filler from Example 1. Detailed Implementation

[0020] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, this application will be further described in detail. It should be understood that the specific embodiments described herein are only for explaining this application and are not intended to limit this application.

[0021] Example 1 A method for preparing a hyperbranched polymer-grafted silicon carbide composite filler specifically includes the following steps: (I) Silicon carbide surface treatment: 100 g of silicon carbide powder with a particle size of 3-5 μm was added to 400 g of 10 wt% sodium hydroxide solution. Stirring was started, the temperature was raised to 80 ℃, and the reaction was kept at a constant temperature for 4 h. The oxide layer on the SiC surface was etched with alkali to introduce silanol groups. After the reaction was completed, heating was stopped, the mixture was cooled, the upper alkali solution was poured off, and the mixture was washed with deionized water until the pH of the washing solution was 7-8. The mixture was washed once with anhydrous ethanol to replace the water, and dried in a vacuum drying oven at 80 ℃ for 12 h. The mixture was then ground and sieved to obtain 100.6 g of hydroxylated silicon carbide, which was sealed and stored for later use. (II) Construction of the interfacial phase: Prepare a mixed solvent of deionized water and anhydrous ethanol with a volume ratio of 1:2. Add 100g of hydroxylated silicon carbide to the mixed solvent and stir at high speed for 1 h to fully wet and disperse it to obtain a dispersion. The terminal amino hyperbranched polymer uses commercially available Cyagen. ®10 g of HBP-NH2-L2 hyperbranched polymer (amino content 3.5 mmol / g, molecular weight 2500) was dissolved in deionized water and slowly added dropwise to the above dispersion. The pH of the system was adjusted to 5.0-6.0 with dilute hydrochloric acid (a weakly acidic environment is conducive to the reaction between amino and hydroxyl groups). The temperature was raised to 75 °C and the reaction was stirred at a constant temperature for 6 h to chemically bond or strongly hydrogen bond the amino groups at the end of HBP onto the SiC surface, thus obtaining SiC-g-HBP slurry. (III) Construction of functional nanoparticle layer: Weigh 20 g of nano alumina and add it to deionized water and ultrasonically disperse for 30 min to make a uniform suspension. Slowly add the suspension to the SiC-g-HBP slurry that has been reacted above, keep the temperature at 75 ℃, and continue to stir and react for 4 h. During this time, the excess amino and cavity structures on HBP will strongly complex and adsorb the nano alumina particles, and firmly fix them on the polymer layer. After the reaction was completed, the mixture was allowed to settle, the supernatant was discarded, and the precipitate was washed three times with deionized water and ethanol alternately to thoroughly remove the physically adsorbed free HBP and alumina. The filter cake was dried in a vacuum drying oven at 60 °C for 24 h, then ground and pulverized to obtain the final functional composite filler.

[0022] Example 2 The difference between this embodiment and Embodiment 1 is that Cyagen is used. ® The HBP-NH2-L2 hyperbranched polymer was replaced with hyperbranched polyethyleneimine HPEI (Sigma-Aldrich 408727 type), with a molecular weight of 2000 and an amino content of 4.5 mmol / g. The rest of the operation was the same, and the functional composite filler was obtained.

[0023] Example 3 The difference between this embodiment and Embodiment 1 is that nano-alumina is replaced with nano-silica, while the rest of the operations are the same, to obtain a functional composite filler.

[0024] Example 4 The difference between this embodiment and Embodiment 1 is that nano-alumina is replaced with nano-zirconia, while the other operations are the same, to obtain a functional composite filler.

[0025] Example 5 The difference between this embodiment and Example 1 is that the amount of the terminal amino hyperbranched polymer added is 5% of the mass of the hydroxylated silicon carbide, while the rest of the operations are the same, to obtain a functional composite filler.

[0026] Example 6 The difference between this embodiment and Example 1 is that the amount of the terminal amino hyperbranched polymer added is 15% of the mass of the hydroxylated silicon carbide, while the rest of the operations are the same, to obtain a functional composite filler.

[0027] Example 7 The difference between this embodiment and Embodiment 1 is that the mass ratio of silicon carbide powder to sodium hydroxide solution is 1:3, while the other operations are the same, to obtain a functional composite filler.

[0028] Example 8 The difference between this embodiment and Example 1 is that the mass ratio of silicon carbide powder to sodium hydroxide solution is 1:5, while the other operations are the same, to obtain a functional composite filler.

[0029] Example 9 The difference between this embodiment and Embodiment 1 is that in step (iii), the mass ratio of nano-alumina to hydroxylated silicon carbide is 0.15:1, while the rest of the operations are the same, thus obtaining a functional composite filler.

[0030] Example 10 The difference between this embodiment and Embodiment 1 is that in step (iii), the mass ratio of nano-alumina to hydroxylated silicon carbide is 0.25:1, while the rest of the operations are the same, to obtain a functional composite filler.

[0031] Example 11 A hyperbranched polymer-grafted silicon carbide composite material comprises, by weight, 100 parts of E-51 type epoxy resin, 30 parts of the functional composite filler prepared in Example 1, and 65 parts of polyamide curing agent. The epoxy resin is heated to 50 °C, and the composite filler is added. Since the composite filler surface is grafted with polymer, it disperses easily in the resin. A uniform black slurry is obtained by stirring at 1500 rpm for 30 min using a high-speed disperser. The system is cooled to below 40 °C, the curing agent is added, and stirring continues for 10 min. The mixture is placed in a vacuum degassing chamber and degassed at -0.1 MPa for 30 min to remove air bubbles introduced by stirring. The degassed adhesive is poured into a preheated mold (coated with a release agent) for curing. The curing procedure is: 90 °C / 2 h, 120 °C / 2 h, 150 °C / 4 h. After natural cooling to room temperature, the material is demolded to obtain the high-performance epoxy resin composite material.

[0032] Example 12 The difference between this embodiment and Embodiment 11 is that the functional composite filler is 20 parts by weight and the polyamide is 60 parts by weight. The rest of the operations are the same to obtain the composite material.

[0033] Example 13 The difference between this embodiment and Embodiment 11 is that the functional composite filler has a weight ratio of 40 parts, the polyamide has a weight ratio of 70 parts, and the rest of the operations are the same to obtain the composite material.

[0034] Example 14 The difference between this embodiment and embodiment 11 is that the functional composite filler prepared in embodiment 2 is used, while the rest of the operations are the same to obtain the composite material.

[0035] Example 15 The difference between this embodiment and embodiment 11 is that the functional composite filler prepared in embodiment 3 is used, while the rest of the operations are the same to obtain the composite material.

[0036] Example 16 The difference between this embodiment and embodiment 11 is that the functional composite filler prepared in embodiment 4 is used, while the rest of the operations are the same to obtain the composite material.

[0037] Example 17 The difference between this embodiment and embodiment 11 is that the functional composite filler prepared in embodiment 5 is used, while the rest of the operations are the same to obtain the composite material.

[0038] Example 18 The difference between this embodiment and Embodiment 11 is that the functional composite filler prepared in Embodiment 6 is used, while the other operations are the same to obtain the composite material.

[0039] Comparative Example 1 The difference between this embodiment and embodiment 11 is that, by weight, 100 parts of epoxy resin and 65 parts of curing agent are used, and no composite filler is included. The remaining operations are the same to obtain the composite material.

[0040] Comparative Example 2 The difference between this embodiment and Embodiment 11 is that, by weight, 100 parts of epoxy resin, 30 parts of silicon carbide, 4.6 parts of nano-alumina, and 65 parts of curing agent are used, while the rest of the operations are the same, to obtain the composite material.

[0041] Comparative Example 3 The difference between this embodiment and Embodiment 11 is that, by weight, the epoxy resin is 100 parts, the KH-550 silane coupling agent modified silicon carbide is 30 parts, the nano alumina is 6 parts, and the curing agent is 65 parts. The remaining operations are the same, and the composite material is obtained.

[0042] Experimental Example 1 X-ray photoelectron spectroscopy (XPS) was performed on nano-alumina, specifically on SiC-g-HBP and SiC-g-HBP@Al2O3 obtained in Example 1. The results are as follows: Figure 1-4 As shown, by Figure 1-2 The results show that in the SiC-g-HBP@Al2O3 sample, the Al 2p binding energy exhibits a chemical shift compared to the peak position of pure nano-alumina. This is because the nitrogen / oxygen atoms in the amino or amide groups on HBP donate their lone pair electrons to the empty orbitals of Al atoms, forming coordinate bonds; Figure 3-4The results show that SiC-g-HBP exhibits a single peak in the N 1s energy level with a binding energy of 399.4 eV, which is attributed to the amino group (CN) in the hyperbranched polymer. When nano-alumina is further loaded, the N 1s peak changes significantly, splitting into two peaks: a free amino peak with a binding energy of 399.2 eV and a coordinated amino peak (N→Al) with a binding energy of 399.95 eV, confirming that nano-alumina is successfully loaded onto the interfacial phase through chemical complexation.

[0043] Experimental Example 2 Thermogravimetric analysis (TGA) was performed on the composite materials prepared in Examples 11-18 and Comparative Examples 1-3 to verify their thermal stability; electrochemical impedance spectroscopy was performed after soaking in 3.5% NaCl for 30 days to verify their corrosion resistance; Taber wear test was performed after 1000 revolutions in a CS-17 wheel mill to verify the wear mass loss; limiting oxygen index was tested according to GB / T 2406 standard and vertical burning test was performed according to UL-94 standard to verify the flame retardant effect; the results are shown in Table 1.

[0044] Table 1 Performance Test Results

[0045] As can be seen from the test results in Table 1, the SiC-g-HBP@Al2O3 composite material prepared using the formulation of this application is significantly superior to the comparative examples in terms of thermal stability, corrosion resistance, wear resistance, and flame retardancy. Compared with the pure resin of Comparative Example 1, the initial thermal decomposition temperature of Example 11 increased by 40 °C, the electrochemical impedance modulus increased by two orders of magnitude, the wear mass loss decreased by 78.8%, and the limiting oxygen index increased from 21% to 29%, reaching the UL-94 V-0 level. Compared with the physically mixed filler of Comparative Example 2, the thermal decomposition temperature of Example 11 increased by 25 °C, the impedance modulus increased by more than one order of magnitude, the wear mass loss decreased by 57.1%, the limiting oxygen index increased by 5 percentage points, and the flame retardancy rating increased from V-2 to V-0. Compared with the silane coupling agent modification of Comparative Example 3, the thermal decomposition temperature of Example 11 increased by 15 °C, the impedance modulus increased by 1.5 times, the wear mass loss decreased by 40%, the limiting oxygen index increased by 3.5 percentage points, and the flame retardancy rating increased from V-2 to V-0.

[0046] The filler content, hyperbranched polymer type, nanoparticle type, and grafting density all affect the performance of the composite material, but all examples are superior to the comparative examples, demonstrating the versatility and superiority of the technical solution of this application. Particularly noteworthy is that the core-shell structure interface phase constructed by the hyperbranched polymer in this invention achieves synergistic effects of multiple functions: the abundant functional groups of the hyperbranched polymer not only form strong chemical bonds with silicon carbide, but also act as a "molecular glue" to load nanofunctional particles in the interface layer, forming a gradient interface structure from the inside out. This design eliminates interface defects between the inorganic filler and the organic matrix, greatly extending the penetration path of corrosive media. The rigid core (silicon carbide) and rigid shell (nanoparticles) give the material excellent corrosion resistance. Furthermore, the flexible hyperbranched layer introduced between the rigid core (silicon carbide) and rigid shell (nanoparticles) acts as a buffer against frictional impacts. Combined with the ball-bearing effect of the nanoparticles, this significantly improves wear resistance. Simultaneously, the nitrogen element in the hyperbranched polymer and the metal element in the nanoparticles form a nitrogen-metal synergistic flame-retardant system at high temperatures, promoting the formation of a dense carbon layer and achieving a V-0 flame retardancy rating. In contrast, neither the unmodified nor the silane coupling agent-modified versions can achieve this multi-functional molecular-level integration, thus limiting performance improvement. This material can be widely used in building materials, aerospace, and other industries.

[0047] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A hyperbranched polymer-grafted silicon carbide composite filler, characterized in that, It includes a silicon carbide core, a terminal amino hyperbranched polymer intermediate layer grafted onto the surface of the silicon carbide core, and a layer of functional nanoparticles loaded on the hyperbranched polymer intermediate layer.

2. The hyperbranched polymer-grafted silicon carbide composite filler according to claim 1, characterized in that, The amino content of the terminal amino hyperbranched polymer is 2.5-4.5 mmol / g, and the molecular weight is 2000-4000; the functional nanoparticles are one of nano-silica, nano-alumina, or nano-zirconia.

3. A method for preparing a hyperbranched polymer-grafted silicon carbide composite filler, characterized in that, Specifically, the following steps are included: (a) Silicon carbide surface treatment: Silicon carbide powder is added to an alkaline solution for treatment to obtain hydroxylated silicon carbide; (II) Construction of the interfacial phase: The hydroxylated silicon carbide was placed in a mixed solvent and ultrasonically stirred to obtain a dispersion; the terminal amino hyperbranched polymer was dissolved and added dropwise to the dispersion to react and obtain SiC-g-HBP slurry; (III) Construction of functional nanoparticle layer: The functional nanoparticles are ultrasonically dispersed to obtain a suspension, and the suspension is added dropwise to the SiC-g-HBP slurry. The active amino groups react with the hydroxyl groups. After the reaction is completed, the functional composite filler is obtained through post-treatment.

4. The method for preparing a hyperbranched polymer-grafted silicon carbide composite filler according to claim 3, characterized in that, The surface treatment in step (1) is carried out at a temperature of 70-90 ℃ for 4 h; the particle size of the silicon carbide powder is 3-5 μm; the concentration of the alkaline solution is 10 wt%; and the mass ratio of the silicon carbide powder to the alkaline solution is 1:3-5.

5. The method for preparing a hyperbranched polymer-grafted silicon carbide composite filler according to claim 3, characterized in that, The mixed solvent in step (ii) consists of water and anhydrous ethanol, with a volume ratio of water to anhydrous ethanol of 1:1-4.

6. The method for preparing a hyperbranched polymer-grafted silicon carbide composite filler according to claim 3, characterized in that, In step (ii), the mass ratio of hydroxylated silicon carbide to mixed solvent is 1:9-11, and the amount of terminal amino hyperbranched polymer added is 5-15% of the mass of hydroxylated silicon carbide; the pH of the reaction system is 5.0-6.0, the reaction temperature is 65-85 ℃, and the reaction time is 6 h.

7. The method for preparing a hyperbranched polymer-grafted silicon carbide composite filler according to claim 3, characterized in that, In step (iii), the mass ratio of the functional nanoparticles to hydroxylated silicon carbide is 0.15-0.25:1; the reaction temperature is 65-85 ℃, and the reaction time is 4 h.

8. The method for preparing a hyperbranched polymer-grafted silicon carbide composite filler according to claim 3, characterized in that, The specific steps of the post-treatment described in step (iii) are as follows: After the reaction is completed, the precipitate is washed three times with deionized water and ethanol alternately, dried at 60 ℃ for 24 h, and then ground into powder.

9. An application of a hyperbranched polymer-grafted silicon carbide composite filler, wherein the composite filler is used to prepare epoxy resin composite materials, characterized in that, The composite material includes epoxy resin, composite filler and curing agent, wherein in the composite filler, the terminal amino hyperbranched polymer intermediate layer undergoes a chemical cross-linking reaction with the epoxy resin through its active amino groups.

10. The application of the hyperbranched polymer-grafted silicon carbide composite filler according to claim 9, characterized in that, By weight, 100 parts epoxy resin, 20-40 parts composite filler, and 60-70 parts curing agent.

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