Preparation method for synthesizing high-temperature-resistant viscous material

Abstract

The invention discloses a preparation method for synthesizing a high-temperature-resistant viscous material. The high-temperature-resistant viscous material is mainly composed of a poly (oxazolidinone) derivative (POL), an AB type hydrophilic-hydrophobic block copolymer, a nano reinforcement, microcapsules and the like. The preparation method comprises the following steps: ultrasonically dispersing the POL, the copolymer and the nano reinforcement in NMP, adding the microcapsule to prepare a pre-glue solution, carrying out argon plasma treatment on a base material, then coating, and carrying out stepped curing to trigger cyclization. The material has excellent high-temperature tolerance and self-repairing capability, is suitable for bonding metal or ceramic structures in extreme environments such as aerospace, nuclear power and the like, and can realize long-term stable bonding and self-repairing in a range of 200-400 DEG C.

Description

A method for preparing a synthetic high-temperature resistant adhesive material Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and specifically to a method for preparing a synthetic high-temperature resistant adhesive material. Background Technology

[0002] The application of high-temperature adhesives in high-temperature environments currently faces multiple technical bottlenecks. Existing solutions have significant shortcomings in terms of temperature resistance, self-healing function, nano-dispersion stability, and industrialization requirements, urgently requiring breakthrough solutions: 1. Limitations in the heat resistance of epoxy resin systems. Existing epoxy resin systems such as CN113462301A, while possessing excellent adhesive strength, have heat resistance that is insufficient to meet the demands of extreme environments. Traditional epoxy resins, such as bisphenol A, typically have a temperature limit ≤180℃. Under high-temperature conditions, such as 300℃, the strength retention rate after 100 hours is less than 50%, mainly due to the high number of flexible groups and insufficient cross-linking density in their molecular chains, leading to accelerated thermal degradation. Although the introduction of organosilicon modification, multifunctional epoxy resins such as AG-80 and TDE-86, or nanofillers such as silica and alumina can improve heat resistance, long-term stability at 280℃ is still not achievable. Furthermore, the high curing temperature of epoxy resins, typically ≥150℃, limits their application in low-temperature curing processes.

[0003] 2. Curing Temperature and Functional Defects of Polyimide Adhesives Polyimide (PI) adhesives possess excellent high-temperature resistance due to the presence of imide rings in their main chain. However, their industrial application faces two major challenges: excessively high curing temperature (PI adhesives require curing at ≥350℃), imposing stringent requirements on the heat resistance of the substrate, resulting in high processing costs and difficulty in compatibility with heat-sensitive materials; and lack of self-healing function (traditional PI materials cannot self-repair after thermal aging or mechanical damage, leading to irreversible degradation of the bonding interface performance and failing to meet the long-term reliability requirements of aerospace, electronic packaging, and other fields).

[0004] 3. Dispersion and Interfacial Compatibility Issues of Nanofillers Introducing nanofillers can improve the thermal conductivity and heat resistance of materials, but direct addition presents two major technical obstacles: A sharp increase in viscosity: the high specific surface area of ​​nanoparticles leads to a 300% increase in system viscosity, severely affecting the operability of industrial processes such as coating and impregnation; Attenuation of interfacial strength: the weak interfacial bonding between nanoparticles and the matrix resin results in a 40% decrease in bond strength, easily forming stress concentration points after thermal aging, accelerating material failure. Existing surface modification techniques only partially improve dispersibility and cannot simultaneously achieve high filling capacity and interfacial stability.

[0005] 4. The Conflict Between Low-Temperature Curing and High-Temperature Performance: To meet the process requirements of composite material molding, electronic packaging, and other fields, low-temperature curing has become a key indicator. However, traditional low-temperature curing systems often sacrifice high-temperature performance, resulting in a sharp decline in the strength of the cured product above 200°C. Developing a system that combines low-temperature curing kinetics with high-temperature thermodynamic stability requires breakthroughs in existing technological bottlenecks in areas such as curing agent design and crosslinking network structure.

[0006] 5. Industry Demands and the Gap with Existing Technologies: Applications such as aerospace engines, high-temperature electronic packaging, and nuclear industry equipment place stringent demands on adhesive materials: long-term service at 280℃, precise temperature-triggered self-healing, stable nanoparticle dispersion, and compatibility with low-temperature curing processes. While existing technologies have achieved breakthroughs in individual performance aspects, they cannot simultaneously meet these multi-dimensional requirements. This leads to frequent early failures, repair failures, and poor process adaptability in practical applications of high-temperature adhesive materials, severely restricting the reliability and service life of high-end equipment. Therefore, there is an urgent need to develop a novel high-temperature adhesive material that, through multi-scale control including molecular structure design, micro-nano composite technology, and intelligent repair mechanisms, systematically solves the synergistic challenges of heat resistance, repair precision, nanoparticle dispersion stability, and low-temperature curing processes, thereby promoting a leapfrog development in high-temperature adhesive material technology. Summary of the Invention

[0007] To achieve the above objectives, this application proposes a method for preparing a high-temperature resistant adhesive material. This high-temperature resistant adhesive material is composed of the following four components: a poly(oxazolidinone) derivative (POL), an oxazolidinone polymer containing epoxy groups, with the general formula: [-O-C6H3(CH3)-C6H4-OC(O)-NH-(CH2)6-NH-C(O)-O-]n; its function is to form a rigid skeleton by cyclization at temperatures >280℃, thereby constituting a stable skeleton structure.

[0008] AB-type amphiphilic block copolymer: Composed of a hydrophilic segment of polyethylene glycol (PEG) and a hydrophobic segment of polycaprolactone (PCL) containing biphenyl mesocrystalline groups, with a total molecular weight of approximately 10,000 Da. PEG accounts for 30% of the total mass, and PCL accounts for 70%. The hydrophobic PCL segment contains biphenyl mesocrystalline groups, a structure that imparts good rigidity and liquid crystal properties to the material, while also enhancing its stability. The presence of biphenyl groups helps promote self-assembly. The hydrophilic and hydrophobic segments are connected by reversible disulfide bonds (-SS-), a structure that gives the material unique dynamic properties. At temperatures >200°C, the disulfide bonds can reversibly break and recombine, thus enabling the material's dynamic adaptability.

[0009] 3. Nanoreinforcement: Boron nitride nanosheets (BNNSs): thickness ≤ 5 nm, aspect ratio > 200; Amino-modified silica nanoparticles: particle size 20-50 nm, amino density 1.2 mmol / g.

[0010] Function: Nanoparticles inhibit high-temperature interfacial slippage and improve adhesion strength and stability through the reaction of amino and POL epoxy groups.

[0011] 4. Modified Microcapsules: The shell material is polyimide, providing high-temperature stability. The microcapsules are grafted with KH-550 silane coupling agent, with a contact angle ≤30°, improving wettability and adhesion to the substrate. The shell thickness to microcapsule size ratio is 1:50-1:100. The internal encapsulation consists of bisphenol F type epoxy resin (EPON862) and dicyandiamide curing agent at a mass ratio of 10:1, providing repair functionality.

[0012] This invention provides a method for preparing a synthetic high-temperature resistant adhesive material, comprising the following steps: 1. Composite solution preparation: 30-60% by weight of POL, 10-25% by weight of AB-type amphiphilic block copolymer, and 5-15% by weight of nano-reinforcing material are added to 200-400g of N-methylpyrrolidone (NMP) solvent. Ultrasonic treatment is then performed at 500W for 30 minutes to ensure uniform dispersion of the nanoparticles in the solvent, resulting in a particle size distribution with a PDI < 0.2.

[0013] Pre-gel preparation: Add 3-10% by weight of KH-550 modified microcapsules to the solution obtained in step 1. Stir at a low speed (≤200 rpm) for 20-40 minutes to avoid microcapsule rupture. "Total weight" refers to the sum of the amounts of POL, nano-reinforcement, AB-type amphiphilic block copolymer, and microcapsules added to the raw materials.

[0014] 3. Substrate Treatment: The substrates to be bonded are subjected to argon plasma activation treatment at a power of 100W for 5 minutes. The substrates include titanium alloys, nickel-based superalloys, and zirconia ceramics. Surface treatment is performed to ensure that the surface energy is ≥70 mN / m, which is beneficial to improving the bonding strength.

[0015] 4. Coating and Step Curing: Apply the pre-adhesive solution evenly to the substrate surface, with a coating thickness of 100-110μm.

[0016] Perform the stepped curing process: ① Low temperature pre-curing: Maintain a constant temperature of 80℃ for 40 minutes to allow the coating to form.

[0017] ② High-temperature repair and cyclization: Heat to 280-320℃ at a rate of 5℃ / min, hold for 30-60 minutes to trigger POL cyclization and form a rigid skeleton structure.

[0018] The present invention has the following significant advantages: 1. Excellent high-temperature bonding stability: The material retains ≥85% of its strength under high-temperature conditions of 400℃ / 100h. This indicates that the adhesive material can withstand high-temperature environments for a long time, and its bonding performance is far superior to that of traditional adhesive materials, meeting the stringent requirements for high-temperature stability in aerospace, high-temperature industries and other fields.

[0019] 2. Excellent self-healing properties: After being repaired at 280-320℃ for 30-60 minutes, the strength recovery rate of the material is ≥90%. This indicates that after being damaged, the material can self-repair at high temperatures through the release of repair agents from microcapsules, restoring its adhesive strength, extending the service life of the material, and reducing maintenance costs.

[0020] 3. KH-550 Modified Microcapsules: The KH-550-modified microcapsule shell improves wettability and adhesion to the substrate, ensuring a good bond between the microcapsule and the substrate. The epoxy resin and curing agent inside the microcapsule provide self-healing capabilities, repairing material damage.

[0021] 4. Simple process and easy to implement: The preparation method of the present invention only requires simple steps such as mixing, coating and step curing. The process flow is easy to control and is suitable for large-scale production.

[0022] 5. Wide range of applications: The materials of this invention are particularly suitable for harsh high-temperature environments and can be applied to aerospace engine components, high-temperature industrial equipment, gas turbines and other fields, with broad application prospects.

[0023] 6. Improved environmental friendliness: The long-term stability and self-healing function of the material reduce the frequency of replacement and maintenance, thereby indirectly reducing resource consumption and waste generation, which has a positive impact on environmental protection.

[0024] In summary, this invention achieves a perfect combination of high-temperature adhesive performance and self-healing properties through the synergistic effect of multiple components, providing a novel solution for bonding in high-temperature environments. It has significant industrial application value and broad market prospects. Attached Figure Description

[0025] Figure 1 shows the measurement of the thickness and diameter ratio of the modified microcapsule shell, where D is the particle size and t is the shell thickness; Figure 2 is a schematic diagram of the POL cyclization reaction mechanism. Detailed Implementation

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0028] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0029] Example 1, referring to Figures 1 and 2, this example provides a preparation and application of a high-temperature resistant adhesive material. The specific implementation method is as follows: Step 1: Raw material preparation POL: 100g of bisphenol F epoxy resin (EPON 1138) and 38.2g of HDI are mixed in 200g of NMP and reacted at 80℃ for 4h to obtain POL with an epoxy content of 0.45 mmol / g; AB type amphiphilic block copolymer: composed of hydrophilic segment polyethylene glycol (PEG) and hydrophobic segment polycaprolactone (PCL) containing biphenyl mesocrystalline groups, its molecular structure is: PEG-[O(CH2)5CO]n-SS-[O(CH2)5CO]m-PEG, where PEG represents polyethylene glycol segment, PCL represents polycaprolactone segment, SS represents disulfide bond, n and m are positive integers, controlling the length of PCL segment, thereby adjusting the flexibility and repair performance of the material.

[0030] Biphenyl mesomorphic group: refers to biphenyl (-Ph-Ph-). In this embodiment, biphenyl is introduced into the PCL segment to obtain a biphenyl-containing PCL segment; the preparation steps of the AB type amphiphilic block copolymer are as follows: 1. Synthesis of biphenyl-containing PCL: 5.0 g of 4,4'-dihydroxybiphenyl, 50 g of ε-caprolactone, and 0.055 g of B(C6F5)3 are reacted at 120℃ for 6 h, and HO-PCL(biphenyl)-OH with a molecular weight of 5000 is obtained by methanol precipitation; 2. Thiolization: 20 g of HO-PCL(biphenyl)-OH and 1.32 g of 3-mercaptopropionic acid are reacted in toluene at 120℃ for 12 h to obtain HO-PCL(biphenyl)-SH; 20 g of HO-PEG-OH (Mn=2000) is added to 3.3 g of 3-mercaptopropionic acid in the same way and reacted in toluene at 120℃ for 12 h to obtain HS-PEG-OH; the amount of 3-mercaptopropionic acid is determined based on the amount of terminal hydroxyl groups.

[0031] 3. Oxidative coupling: 15 g of HO-PCL (biphenyl)-SH and 5 g of HS-PEG-OH were dissolved in toluene, and 1.5 g of 30% H2O2 aqueous solution was added. The mixture was reacted at 25°C for 24 h, and the precipitate was dried to obtain the AB type amphiphilic block copolymer.

[0032] Nanoreinforcement: Amino-modified SiO2 with a particle size of 35 nm was surface-modified using the silane coupling agent 3-aminopropyltriethoxysilane to impart amino functional groups and enhance its compatibility with POL. The amino group density of the modified SiO2 was 1.25 mmol / g. The modification steps were as follows: 10 g of SiO2 was dispersed in 200 ml of anhydrous ethanol and sonicated at 300 W for 20 min; 2.5 g of KH-550 was added and the mixture was refluxed at 80 °C for 6 h; the mixture was centrifuged at 8000 rpm for 10 min, washed three times with anhydrous ethanol, and vacuum dried at 80 °C for 12 h to obtain amino-modified SiO2.

[0033] NMP (N-methylpyrrolidone) was used as a solvent; KH-550 was used to modify the microcapsules.

[0034] The specific process flow of KH-550 modified microcapsules is as follows: 1. Material preparation: The microcapsule shell is made of polyimide-Kapton® purchased from DuPont; the internal encapsulation uses EPON 1138 bisphenol F epoxy resin produced by Hexion, and DICY 10 dicyandiamide curing agent produced by Ajinomoto Fine-Techno Co., Inc., with a mass ratio of 10:1.

[0035] KH-550 silane coupling agent: 3-aminopropyltriethoxysilane, used as a modifier.

[0036] Solvent: The volume ratio of water-alcohol mixed solvent is ethanol:water = 9ml:1ml; Preparation of unmodified original microcapsules: EPON 1138 epoxy resin and DICY 10 curing agent are weighed at a mass ratio of 10g:1g; Then, the polyimide powder is impregnated with the epoxy resin system: Impregnation method: The polyimide powder is immersed in the epoxy resin system to allow the material to fully adsorb the epoxy resin.

[0037] The epoxy resin-impregnated polyimide powder was dispersed in a water-alcohol mixture and emulsified using one of the following mechanical stirring methods: The mixture was stirred at high speed (5000 rpm) using a high-speed homogenizer to form a particulate system. This process was maintained for 30 minutes to ensure complete emulsification.

[0038] Emulsification creates microparticle structures, encapsulating an epoxy resin curing agent system in microcapsules. The polyimide microcapsules encapsulating the epoxy resin system are then cured at 280°C for 2 hours to ensure complete cross-linking and curing of the epoxy system. After curing, the microcapsules are separated by centrifugation.

[0039] The microcapsules were washed repeatedly with a mixture of ethanol and water to remove any remaining unreacted substances and impurities. They were then dried at 60°C to constant weight in a ventilated or vacuum drying oven to obtain the unmodified pristine microcapsules.

[0040] 2. Preparation of KH-550 solution for modification: Dissolve a certain amount of KH-550 silane coupling agent in a solvent to prepare a 5% solution.

[0041] 3. Dispersion of modified microcapsules: Disperse the unmodified original microcapsules in KH-550 solution at a solid-liquid ratio of 1g:20ml and stir thoroughly to ensure uniform dispersion of microcapsules.

[0042] Modification reaction: The dispersion system is placed at room temperature for the modification reaction. Stirring is maintained, and the reaction time is typically 4 hours. KH-550 will chemically react with the polyimide shell to modify the shell surface. During the reaction, continuous stirring is required to ensure sufficient contact between the modifier and the microcapsule shell.

[0043] Cleaning and Drying: After the modification reaction is complete, the modified microcapsules are centrifuged and the shells are washed multiple times with solvent to remove unreacted KH-550 and other residues. After cleaning, the modified microcapsules are dried in a vacuum oven or fume hood at a temperature typically of 60°C until constant weight is achieved.

[0044] 4. Detection and characterization of contact angle test: Use a contact angle measuring instrument to test the contact angle of the modified microcapsule shell and ensure that it is below 30°.

[0045] Particle size and shell thickness measurement: Using scanning electron microscopy (SEM) as shown in Figure 1, the particle size and shell thickness of the modified microcapsules were measured, ensuring that the ratio of shell thickness to microcapsule particle size was 1:50–1:100. After KH-550 surface modification, the particle size and shell thickness of the microcapsules were not significantly different from the unmodified original microcapsules; the modification only improved interfacial compatibility through chemical bonding.

[0046] Step 2 Material Preparation Process 1. Ultrasonic Dispersion: Add 42g POL, 15g AB type amphiphilic block copolymer and 8g nano-reinforcement to 200g (194ml) of NMP and use an ultrasonic generator with power: 500W and frequency: 40kHz to perform ultrasonication for 30min to ensure uniform dispersion of each component.

[0047] 2. Microcapsule addition and mixing: Slowly add 5g of KH-550 modified microcapsules.

[0048] 3. Stirring: Stir at 150 rpm for 20 minutes to ensure that the microcapsules are evenly dispersed in the mixture.

[0049] 4. TC4 Titanium Alloy Surface Treatment: Argon was used as the protective gas. Argon plasma treatment was performed using a Leybold Plasma 500 system with the following parameters: power 100W, treatment time 5 minutes. After treatment, the surface energy of the TC4 titanium alloy was 72 mN / m.

[0050] Coating and curing: Use a scraper to evenly coat the mixture onto the surface-treated TC4 titanium alloy plate.

[0051] Step curing: Place the coated sample in an XMTD-5600 electric heating drying oven for step curing. The step curing steps are: 1. 80℃ / 40min 2. Increase the temperature to 300℃ at a rate of 5℃ / min and hold at 300℃ for 45min. The POL cyclization reaction mechanism is shown in Figure 2: At high temperatures ≥280℃, the epoxy groups on the POL chain are activated.

[0052] The strain of the epoxy three-membered ring makes it prone to ring-opening reactions at high temperatures.

[0053] Nucleophilic attack and cross-linking: The open-ring epoxy group forms an oxonium intermediate which is attacked by nucleophilic sites on the adjacent POL chain. These nucleophilic sites originate from: nitrogen atoms (N) on the oxazolidinone ring: nitrogen atoms in the oxazolidinone ring (especially in secondary amine forms) have a certain degree of nucleophilicity and can attack activated epoxy groups at high temperatures ≥280℃; and potential hydroxyl (-OH) or carboxyl (-COOH) groups in the system: if -OH or -COOH is present in POL or its decomposition products, they are also strong nucleophiles and can attack epoxy groups.

[0054] An example of attack, taking the nitrogen attack of oxazolidinones as an example: POL1-(epoxy group) + POL2-(oxazolidinone-N) → POL1-CH2-CH(OR)-O - ... + N-POL2→POL1-CH2-CH(OR)-ON-POL2 forms a new CN bond chain. Chain growth and network formation: This reaction can occur at multiple sites. Multiple epoxy groups on a POL chain can be attacked by multiple nucleophilic sites on other POL chains.

[0055] Through this epoxy group-nucleophilic site (N / O) reaction, covalent cross-linking points are formed between different POL molecular chains, such as new ether bonds (COC) and amine bonds (CN).

[0056] Rigid framework formation: This widespread intermolecular cross-linking reaction transforms POL from a linear or branched structure into a highly cross-linked three-dimensional network structure. The newly formed cross-links (COC, CN) and the inherent stable oxazolidinone rings together constitute the rigid framework of the material.

[0057] This dense cross-linked network significantly improves the material's thermal stability, mechanical strength, and dimensional stability at high temperatures.

[0058] Example 1: A high-temperature resistant adhesive material was prepared according to the above steps. This material was coated onto a TC4 titanium alloy substrate, and after a series of curing processes, a uniform and dense coating was formed. This coating exhibits stable adhesion under high-temperature conditions, and due to the introduction of AB-type amphiphilic block copolymers and KH-550 modified microcapsules, it possesses certain flexibility, fracture toughness, and self-healing properties, effectively reducing high-temperature corrosion and extending the service life of the TC4 titanium alloy. It has potential application value in aerospace and aviation fields.

[0059] Example 2 provides the preparation and application of high-temperature adhesive materials from unmodified original microcapsules. The specific operation steps are as follows: 1. Material preparation Microcapsule shell material: Polyimide-Kapton® purchased from DuPont Encapsulation material: EPON 1138 bisphenol F epoxy resin produced by Hexion Curing agent: DICY 10 dicyandiamide curing agent produced by Ajinomoto Fine-Techno Co., Inc. Solvent: A mixture of ethanol and water in a volume ratio of 9 ml: 1 ml 2. Premixing Weigh EPON 1138 epoxy resin and DICY 10 curing agent at a mass ratio of 10:1.

[0060] 3. Interlayer coating and microcapsule formation: Impregnating polyimide powder with epoxy resin system: Impregnation method: Immerse polyimide powder in epoxy resin system to allow the material to fully adsorb epoxy resin.

[0061] By emulsifying to form a microparticle structure, microcapsules are formed to encapsulate the epoxy resin curing agent system.

[0062] 4. Physical curing: The polyimide microcapsules encapsulating the epoxy resin system are placed at 60°C for drying and curing to ensure that the epoxy system is fully cross-linked and cured.

[0063] 5. After washing and drying, the microcapsules are separated by centrifugation.

[0064] Wash repeatedly with a mixture of ethanol and water to remove residual unreacted substances and impurities.

[0065] Unmodified pristine microcapsules were obtained by drying at 60°C to constant weight in a ventilated or vacuum drying oven. The results showed that the unmodified pristine microcapsules had an average particle size of 55 μm, a shell thickness of 0.6 μm, and a contact angle of 75°.

[0066] Step 2: The adhesive preparation is the same as in Example 1.

[0067] POL 42g + AB type amphiphilic block copolymer 15g + nano-reinforcement 8g + NMP 200g → sonicate at 500W for 30min, add 5g of unmodified original microcapsules → stir at 150rpm for 20min.

[0068] Step 3: Preparation of test samples, same as the TC4 titanium alloy surface treatment in Example 1.

[0069] Key process description: Microcapsules without modifiers: No silane modifiers such as KH-550 are used. The microcapsule surface is relatively hydrophobic, with a large surface contact angle and weak interfacial bonding with the matrix.

[0070] Features and differences: No surface modification: Compared with modified microcapsules, unmodified original microcapsules do not have surface functional group adjustments, resulting in poorer interfacial bonding performance and potentially inferior repair effects compared to modified microcapsules.

[0071] The materials prepared in Examples 1 and 2 were tested for their repair capabilities.

[0072] Repair effect test method: Prepare TC4 titanium alloy with specifications of 25mm×12.5mm as test sample, and test the initial shear strength with hydraulic universal testing machine; artificially scratch the bonded sample, scratch the bonding area to a depth of 100μm, and then heat repair at 300℃ for 45 minutes. Finally, test the strength of the repaired material.

[0073] The results are shown in Table 1:

[0074] Table 1 verifies the necessity of microcapsule surface modification. An unmodified control group, i.e., Example 2, was added. Except for the absence of KH-550 modification in the microcapsules, the other components and processes were the same as in Example 1. Test results show that the unmodified original microcapsules, due to poor interfacial compatibility (contact angle 75°) and poor repair ability, achieved a repair recovery rate of only 71.0%, significantly lower than the 92.3% of the present invention group. This confirms that KH-550 modification is a necessary technical feature for achieving efficient repair.

[0075] Reasons for performance degradation of unmodified original microcapsules: High contact angle of 75°: This leads to poor compatibility between the microcapsules and the POL matrix, and the repair agent cannot effectively wet the damaged interface after release; No KH-550 modification: The lack of Si-OC covalent bond bridging results in thermal stress cracks at the interface under high temperature; Conclusion: KH-550 modification improves the repair recovery rate by 21.3% by reducing the contact angle and enhancing interfacial bonding.

[0076] Comparative Example 1 provides the preparation and application of traditional microcapsule self-healing materials. The specific implementation method is as follows: Step 1: Microcapsule preparation Shell material: urea-formaldehyde resin; Core material: dicyclopentadiene (DCPD).

[0077] Process: ① Emulsify 10g DCPD and 1g vinylbenzyl chloride using a high-speed homogenizer at 3000rpm for 15min; ② Add an aqueous solution containing 5g urea and 1.5g ammonium chloride, and react at 60℃ for 3h; ③ Filter and dry at 60℃ to obtain microcapsules.

[0078] Step 2: Adhesive preparation

[0079] Table 2 Step 3: Curing process 120℃-2h+150℃-1h.

[0080] Step 3: Substrate pretreatment and bonding ① Treat the surface of the TC4 titanium alloy substrate to be bonded in the same way as in Example 1; ② Apply the prepared adhesive evenly to the surface of the substrate; ③ Align the two substrates, apply pressure, and cure.

[0081] Curing procedure: Cur at 120℃ for 2 hours; then cure at 150℃ for 1 hour.

[0082] The high-temperature resistance of the adhesives from Examples 1, 2, and Comparative Example 1 was verified. The three samples were placed in a 400°C muffle furnace, and strength tests were conducted at 0h, 24h, and 100h. The results are shown in Table 3.

[0083] Table 3 Comparative Example 1: The material failed due to complete carbonization at 400℃, resulting in a strength of 0 MPa; Example 2: Due to interfacial bonding defects, the strength was lower than that of Example 1.

[0084] Comparative Example 2 provides an adhesive strength test of a high-temperature resistant adhesive material prepared in Example 1 without substrate pretreatment. The specific implementation method is as follows: 1. The only difference between the preparation method and Example 1 is the substrate treatment.

[0085] Substrate treatment: TC4 titanium alloy was used directly without argon plasma treatment. The measured surface energy was 48 mN / m, which is much lower than the 72 mN / m after treatment in Example 1.

[0086] The other steps are completely replicated from Example 1.

[0087] The bonded parts of Comparative Example 2 were placed in a muffle furnace at 400℃, and samples were taken for testing at 0h, 24h, and 100h. The results are shown in Table 4.

[0088] Table 4 shows the difference in adhesive performance between Comparative Example 2 and Example 1. This difference is mainly due to the influence of substrate pretreatment on surface energy, which in turn affects wettability, adhesive interface formation, and high-temperature durability. Argon plasma treatment increases the surface energy of the titanium alloy, improves the wettability of the adhesive, and promotes chemical bonding and physical adsorption between the adhesive and the titanium alloy surface, ultimately improving adhesive strength and retention at high temperatures. The untreated substrate exhibits lower surface energy, resulting in poor adhesive wettability, easily damaged adhesive interfaces, lower adhesive strength, and significant degradation in high-temperature performance.

[0089] The following table summarizes the data from all embodiments and comparative examples:

[0090] Table 5 shows that the effectiveness of the core solution was verified by Example 1. This solution integrates POL, AB-type amphiphilic block copolymer, nano-reinforcement and KH-550 modified microcapsules, achieving excellent high-temperature stability and self-healing ability. Under the condition of 400℃ / 100h, the strength retention rate reached 85.0% and the strength recovery rate after repair reached 92.3%.

[0091] Example 2 highlights the importance of the KH-550 modified microcapsules by comparing them with the unmodified original microcapsules. The unmodified group showed a decrease in both strength and repair capability, demonstrating that KH-550 modification enhances compatibility with the substrate, promotes effective release and interfacial bonding of the repair agent, and is key to achieving efficient repair.

[0092] Comparative Example 1 uses traditional self-healing materials, which completely fail at 400℃, highlighting the significant advantages of the material of the present invention in high temperature resistance. The high-temperature rigid skeleton and self-healing system of POL-based materials are its core competitiveness.

[0093] Comparative Example 2 verified the importance of substrate pretreatment. The adhesive properties of the substrate that was not treated with argon plasma decreased significantly, indicating that surface treatment is crucial for improving interfacial wettability and promoting chemical bonding, thereby ensuring adhesive strength and high-temperature retention.

[0094] It should be particularly noted that the various embodiments listed in this specification and accompanying drawings are intended to illustrate the technical solutions and advantages of the present invention, and not to limit the scope of protection of the present invention. Without departing from the core ideas and technical effects of the present invention, those skilled in the art can make any form of improvement, substitution, combination, or modification to the structural arrangement, process parameters, material selection, control logic, etc., of the described embodiments; any obvious changes based on the same concept should be considered equivalent solutions of the present invention and should be included within the scope of protection defined by the claims of the present invention. The actual scope of protection of the present invention is determined by the appended claims and should be correctly understood in conjunction with the specification and accompanying drawings.

Claims

1. A method for preparing a synthetic high-temperature resistant adhesive material, characterized in that, Includes the following steps: S1. Disperse poly(oxazolidinone) derivative (POL), AB-type amphiphilic block copolymer and nano-reinforcement in NMP solvent, and sonicate at 500W for 30min to obtain a composite solution; wherein, the poly(oxazolidinone) derivative (POL) is an oxazolidinone polymer with epoxy groups, which can cyclize to form a rigid skeleton at temperatures above 280℃; the nano-reinforcement is selected from boron nitride nanosheets or amino-modified silica nanoparticles with a particle size of 20–50 nm; S2. Add microcapsules to the composite solution obtained in step S1, and stir at a speed ≤200 rpm to obtain a pre-gel solution; wherein, the shell of the microcapsule is polyimide, and the inside is encapsulated with bisphenol F type epoxy resin and dicyandiamide curing agent in a mass ratio of 10:1; S3. Treat the substrate with argon plasma at 100W for 5min to make its surface energy ≥70 mN / m; S4. Coat the pre-gel solution and then cure in stages.

2. The method for preparing a synthetic high-temperature resistant adhesive material according to claim 1, characterized in that, The obtained high-temperature resistant adhesive material, based on the total mass of component a and b, includes: a. poly(oxazolidinone) derivative (POL): 30–60%; b. AB-type amphiphilic block copolymer: 10–25%; c. nano-reinforcement: 5–15%; d. microcapsules: 3–10%.

3. The method for preparing a synthetic high-temperature resistant adhesive material according to claim 1, characterized in that... The poly(oxazolidinone) derivative (POL) is prepared from bisphenol F epoxy resin and hexamethylene diisocyanate (HDI).

4. The method for preparing a synthetic high-temperature resistant adhesive material according to claim 1, characterized in that, The microcapsules are modified with KH-550 silane coupling agent, with a contact angle ≤30° and a shell thickness to microcapsule particle size ratio of 1:50–1:

100.

5. The method for preparing a synthetic high-temperature resistant adhesive material according to claim 1, characterized in that, The AB-type amphiphilic block copolymer is composed of a hydrophilic segment of polyethylene glycol (PEG) and a hydrophobic segment of polycaprolactone (PCL) containing biphenyl mesocrystalline groups, with the chains crosslinked by disulfide bonds.

6. The method for preparing a synthetic high-temperature resistant adhesive material according to claim 1, characterized in that, The step curing process includes: ① low-temperature pre-curing: 80℃ / 40min; ② high-temperature cross-linking: increasing to 280-320℃ at 5℃ / min and holding for 30-60min to trigger POL cyclization.

7. The method for preparing a synthetic high-temperature resistant adhesive material according to claim 1, characterized in that, The substrate is a titanium alloy, a nickel-based high-temperature alloy, or a zirconium oxide ceramic.

8. A synthetic high-temperature resistant adhesive material prepared by the method according to any one of claims 1-7, characterized in that, The material has high temperature resistance and repair capability, achieving stable bonding for a long time in the temperature range of 200°C to 400°C. After mechanical damage, it can self-repair by releasing the repair agent through microcapsule rupture and keeping it at 280-320°C for 30-60 minutes.

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