Super-tough, high-tg and controllable degradation thermosetting epoxy resin, preparation method and application thereof

Abstract

This disclosure relates to an ultra-tough, high-strength... T g Furthermore, this study explores controllable degradable thermosetting epoxy resins, their preparation methods, and applications, aiming to address the challenges of achieving both high rigidity and high toughness in traditional epoxy resins, as well as their non-degradability after molding. Specifically, it employs unsaturated hydrocarbon-terminated polysilsesquioxane JB-POS to modify the epoxy resin. Through segmented crosslinking and kinetic control, JB-POS undergoes in-situ self-assembly within the epoxy matrix to generate a uniform nano-core-shell structure. This structure forms the core of the material, achieving high rigidity, high toughness, and high... T g The material exhibits a synergistic effect between performance and structural stability. Furthermore, the dynamic ester and silicon-oxygen bonds within it endow it with on-demand and controllable degradation properties, achieving a synergistic balance between high toughness, high glass transition temperature, and controllable degradation performance. In addition, the preparation process disclosed herein is simple and can meet the needs of high-end fields such as electronics and aerospace, demonstrating promising prospects for industrial application.

Description

Technical Field

[0001] This disclosure relates to the field of epoxy resin technology, specifically to a super-tough, high-strength epoxy resin... T g Furthermore, it describes the controllable degradation of thermosetting epoxy resins, their preparation methods, and applications. Background Technology

[0002] Epoxy resins, due to their excellent mechanical properties, adhesion, chemical stability, and processability, are widely used in electronics, aerospace, automotive manufacturing, and composite materials, making them important structural polymer materials. However, traditional epoxy resins suffer from two major technical challenges: firstly, achieving both high rigidity and high toughness is difficult; strength and toughness are a challenging contradiction in the field of thermosetting epoxy resins. The cross-linked network formed after curing pure epoxy resin is dense but brittle, with poor fracture toughness, making it prone to cracking under external forces. Although existing technologies use elastomers, hyperbranched polymers, and core-shell rubber particles for toughening, this often leads to a decrease in the material's glass transition temperature (GTE). T g First, the heat resistance decreases, failing to meet the combined demands of high-end applications for materials with high heat resistance and toughness. Second, it is non-degradable after molding. Epoxy resin forms a three-dimensional cross-linked network after curing, exhibiting extremely strong chemical stability. It is difficult to degrade naturally after disposal, becoming "white pollution." Furthermore, a large number of high-end epoxy resin products cannot be recycled after disposal, resulting in serious waste of resources. To address this issue, existing technologies attempt to introduce stimulus-responsive, dynamically reversible covalent bonds into epoxy resins. These covalent bonds can undergo reversible breakage under specific chemical and temperature conditions, enabling controlled chemical degradation of the material. Representative bond types include disulfide bonds, imine bonds, and DA reversible addition bonds. However, the introduction of such chemical bonds often disrupts the density of the cross-linked network, leading to a significant decrease in the material's mechanical properties and heat resistance. While conventional toughening modification methods such as elastomers, hyperbranched polymers, and non-covalent sacrificial bonds can improve the toughness of epoxy resins to some extent, they often come at the cost of sacrificing thermal stability and rigidity. Furthermore, the poor compatibility between heterogeneous toughening agents and epoxy groups can easily lead to abnormally high viscosity and uneven phase separation, resulting in shortcomings in the material's mechanical properties and an inability to achieve a synergistic balance of heat resistance, mechanical strength, rigidity, and toughness. In addition, some modified epoxy resin raw materials have high melting points and low reactivity, requiring high-temperature curing, resulting in complex molding processes and high energy consumption, further increasing the cost of industrial production.

[0003] While the epoxy resin with a dynamic semi-interpenetrating network and its preparation method disclosed in CN118755029B possesses high strength, high toughness, and green degradability, it still suffers from the following shortcomings: high processing viscosity (both curing agents are solids), short operating window, and high curing temperature (up to 190℃); low upper limit of heat resistance: Tg only ≥150℃, hydrogen bond dissociation and network relaxation under long-term high temperature (>120℃), resulting in significant attenuation of strength and toughness; slow dynamic response: ester bond degradation requires 180-200℃, 4-8 hours of pure water + 1-2MPa pressure, harsh conditions, and high energy consumption, not "green and mild degradation"; moreover, the preparation process involves many steps, a long cycle (total time > 48 hours), and high energy consumption. Post-treatment is required after resin molding, and the impregnation method is difficult to control the solvent penetration depth and uniformity, easily leading to surface enrichment and internal deficiencies, resulting in performance stratification and poor batch stability, making it unsuitable for scenarios such as photopolymerization rapid prototyping / electronic packaging / wet prepreg of composite materials.

[0004] Therefore, it is necessary to develop a material that combines ultra-toughness and high strength. T g The development of epoxy resins that can be degraded on demand and have a simple preparation process has become a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] In view of this, the present disclosure provides an ultra-tough, high-strength... T g Furthermore, it describes controllable degradable thermosetting epoxy resins, their preparation methods, and applications, solving the problem that existing thermosetting epoxy resins cannot simultaneously achieve high toughness, high glass transition temperature, and controllable degradation.

[0006] To achieve the aforementioned objectives, in a first aspect, the ultra-tough and high-strength materials described in this disclosure... T g Furthermore, the preparation method of controllably degradable thermosetting epoxy resin includes: Unsaturated glycidyl ester type epoxy monomer, unsaturated hydrocarbon-terminated polysilsesquioxane and polyamine curing agent are uniformly mixed to obtain an epoxy composite premix system; the epoxy composite premix system is then subjected to heat curing and light curing in sequence to obtain the epoxy resin. The epoxy resin crosslinking network forms a nano-core-shell phase structure with a cage-like polysilsesquioxane core and an unsaturated double bond copolymer rigid network as the shell.

[0007] Preferably, the epoxy composite premix system has the following component ratios by mass: 100 parts epoxy monomer, 2-10 parts polysilsesquioxane, and 10-15 parts polyamine curing agent.

[0008] Preferably, the core diameter of the nano-core-shell phase structure is 10~80 nm, and the shell thickness is 5~30 nm.

[0009] Preferably, the unsaturated hydrocarbon-terminated polysilsesquioxane is a cage-like polyhedral oligomeric silsesquioxane, having a closed cage-like inorganic core formed by Si-O-Si bonds, with one or more of methacryloyloxy, acryloyloxy, and methacrylamide groups bonded to the outer surface of the cage core, and the structure being regular T B It has a cage-like structure; its degree of branching is 6-8, its number-average molecular weight Mn is 800-1200 g / mol, its silicon content is 12-18 wt%, its double bond retention rate is ≥90%, and its volatile matter is ≤1.0 wt%.

[0010] Preferably, the method for preparing the cage-like polyhedral oligomeric silsesquioxane includes: One or more of methacryloylsilane, acrylic silane, and methacrylamide triethoxysilane are mixed evenly with tetramethylammonium hydroxide pentahydrate and isopropanol, and the silane monomers are hydrolyzed and gradually condensed to prepare the silane with a molecular size of 1.0 to 3.0 nm.

[0011] Preferably, the unsaturated glycidyl ester type epoxy monomer is selected from one or more of diglycidyl diacrylate and its epoxy derivatives, 4-hydroxybutyl acrylate glycidyl ester and its epoxy derivatives, diglycidyl tetrahydrophthalate and its epoxy derivatives, and glycidyl itaconic acid ester and its epoxy derivatives; and / or, The polyamine curing agent is selected from one or more of isophorone diamine, 1,3-cyclohexanediamine, 2,4-diaminotoluene, 2,4-p-phenylenediamine, 4,4'-diaminodiphenylmethane, and 4,4'-diaminodiphenyl sulfone.

[0012] Preferably, the epoxy derivative of glycidyl itaconic acid ester is glycidyl itaconic acid ester diepoxide, and its preparation method uses glycidyl itaconic acid ester as a raw material, PW 12 / SBA-15 is used as a heterogeneous catalyst, anhydrous acetonitrile is used as a solvent, and hydrogen peroxide is used as an oxidant to prepare the glycidyl itaconic acid ester diepoxide via a selective epoxidation reaction.

[0013] Preferably, the method for uniformly mixing the unsaturated glycidyl ester type epoxy monomer, the unsaturated hydrocarbon-terminated polysilsesquioxane, and the polyamine curing agent includes: The epoxy monomer and the polysilsesquioxane are uniformly mixed at 25~40°C, and then vacuum degassing is performed to obtain a homogeneous premixed adhesive. The polyamine curing agent is added to the homogeneous premixed adhesive, dispersed evenly, and vacuum degassing is performed again to obtain the epoxy composite premixed system.

[0014] Preferably, the method for sequentially heating and photocuring the epoxy composite premix system includes: After curing at 60~150℃ for 6~8 h, it is then photocured at room temperature for 10~20 min. The photocuring light source is a 365 nm UV-LED with a light intensity of 500 mW / cm².

[0015] Secondly, the ultra-tough and high-strength materials described in this disclosure... T g Furthermore, the thermosetting epoxy resin can be controlled to degrade and is prepared by any of the methods described in the first aspect.

[0016] Thirdly, the ultra-toughness and high strength described in the second aspect of this disclosure T g Furthermore, controllable degradable thermosetting epoxy resins are used in the preparation of electronic device structural parts, lightweight aerospace components, high-end equipment adhesive layers, and composite material matrices.

[0017] The present invention has the following beneficial effects: The resin of this invention, through in-situ construction of a nano-core-shell structure, overcomes the limitations of traditional physical blending for toughening, achieving integrated structural design, in-situ construction, and performance locking. This nano-core-shell structure significantly improves the material's toughness and... T g No decrease, that is, achieving both high strength and toughness of the material. T g This breakthrough simultaneously resolves long-standing industry contradictions; at the same time, the core and shell are anchored in situ, resulting in ultra-stable structure and improved material resistance to solvents and high and low temperature cycles, i.e., no warping and no cracking; in addition, it can achieve simultaneous core-shell disintegration and bond breaking, resulting in more thorough and controllable degradation: depolymerization rate ≥85%, and recyclable monomers; moreover, this invention adopts an asynchronous curing in-situ core-shell formation process, which does not require high temperature, solvents, or post-treatment, making the preparation method extremely simple and industrializable. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the specification, serve to illustrate the technical solutions of this disclosure.

[0019] Figure 1 Temperature-rheology diagram of the mixed resin prepolymer provided in Example 1. a - Viscosity as a function of shear rate; b - Viscosity as a function of time, used to characterize pot life and shelf life; Figure 2 The dynamic thermomechanical analysis (DMA) diagram of the epoxy resin provided in Example 1; Figure 3The stress-strain curve of the epoxy resin provided in Example 1; Figure 4 The images show negative-stained TEM images of the epoxy resin obtained in Example 1 under in-situ stretching; the phase regions reflect the size of the silicon nucleus, specifically before stretching (a), at 4% stretching strain (b), and a magnified view at 4% stretching strain (c). Figure 5 The image shows a small-angle X-ray scattering pattern of the epoxy resin obtained in Example 1, which demonstrates the size of its core-shell structure phase (core + shell). Detailed Implementation

[0020] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. Although various aspects of embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise. The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0021] To address the problems in the background technology, this disclosure provides a preparation with ultra-toughness and high... T g Furthermore, the core technology of thermosetting epoxy resins with synergistic controllable degradation properties lies in: An epoxy composite premix system obtained by mixing unsaturated glycidyl ester type epoxy monomers, unsaturated hydrocarbon-terminated polysilsesquioxanes (JB-POS), and polyamine curing agents is subjected to heat curing and light curing treatments in sequence. During the segmental ring-opening crosslinking process between the polyamine and epoxy resin, the unsaturated hydrocarbon-terminated polysilsesquioxanes are self-assembled in situ, forming a nano core-shell phase structure with cage-like polysilsesquioxanes as the core and an unsaturated double bond copolymer rigid network as the shell within the epoxy resin crosslinking network.

[0022] The above-mentioned JB-POS in-situ self-assembly mechanism for forming nano-core-shell phase structures: The first step is rapid crosslinking: the glycidyl ester groups of the epoxy monomer rapidly open the ring with the amine curing agent to form a continuous epoxy first network; The second step is delayed nucleation: the double bonds on the unsaturated hydrocarbon-terminated polysilsesquioxane JB-POS undergo delayed photocatalytic self-polymerization after epoxy network polymerization, and the molecules aggregate to form flexible nanonuclei. The third step is in-situ coating to form a shell: the epoxy network wraps the core surface in situ and is chemically anchored to form a stable core-shell-continuous phase structure.

[0023] This nano-core-shell structure is controlled by cross-linking kinetics, exhibiting uniform size, no macroscopic phase separation, low internal stress, and excellent dimensional stability.

[0024] This nano-core-shell structure serves as a material strengthening and high-strength... Tg With a dimensionally stable core carrier, the following can be achieved: (1) Stress transfer and energy dissipation: the core-shell interface debonding, shell yielding, and core skeleton bearing work together to improve fracture toughness by ≥80%; (2) High T g With high rigidity: JB-POS rigid core and multi-branched characteristic enhancement network enable T g ≥210℃, tensile strength ≥180 MPa; (3) Stable structure: core and shell anchoring inhibits phase migration, mechanical properties retention rate ≥95% after high and low temperature cycling; at the same time, the hydrolytic properties of dynamic ester bonds and silicon-oxygen bonds give it controllable degradation, and it can achieve overall depolymerization under acid-base hydrolysis or alcoholysis conditions. After degradation, the core and shell structure disintegrates, and oligomers and monomers can be recycled.

[0025] The epoxy resin prepared by this invention can achieve ultra-toughness and high strength. T g The technical mechanism of the synergistic effect of on-demand degradation can be divided into the following three aspects: ①High T g The realization mechanism: JB-POS's high molecular rigidity and highly branched topology form a dense cross-linking network with epoxy resin, which greatly improves the cross-linking density of the material; at the same time, the abundant urethane and hydroxyl groups in the system form high-density intermolecular hydrogen bonds, which further restricts the movement of polymer chain segments and inhibits chain segment relaxation, thereby significantly increasing the glass transition temperature of the material and greatly enhancing its heat resistance and structural stability.

[0026] ② Mechanism of achieving ultra-high toughness: The reaction rate of glycidyl ester-type epoxy groups with amine curing agents is much higher than the reaction rate of double bond photocatalytic self-polymerization, and the photocatalytic self-polymerization reaction of double bonds in JB-POS needs to be based on the above reaction. Therefore, asynchronous crosslinking occurs, inducing the system to gradually transform from molecular interpenetration to incompatible aggregation, and finally forming a uniform phase-separated structure in which JB-POS elastic microdomains are wrapped by an epoxy interpenetrating network shell; this structure can effectively transfer and disperse external stress, avoiding cracking caused by stress concentration; at the same time, dynamic hydrogen bonds can dissociate and recombine under external force, combined with the chain segment relaxation of JB-POS elastic microdomains, efficiently dissipating external force energy, thus greatly improving the fracture toughness, tensile strength and shear resistance of the material, achieving a significant improvement in strength and toughness.

[0027] ③ Mechanism for on-demand degradation: Hydrolyzable ester bonds are introduced into epoxy resin as degradation sites. These ester bonds are stable under normal use conditions and do not affect the overall performance of the material. However, under artificially controlled acid-base or alcoholysis degradation conditions, the ester bonds undergo hydrolysis and breakage, which leads to the gradual depolymerization of the crosslinked network of the material and the destruction of the dense three-dimensional structure, ultimately achieving on-demand degradation and recycling of epoxy resin.

[0028] In this disclosure and possible embodiments, the epoxy composite premix system, by mass parts, has the following component ratios: 100 parts epoxy monomer, 2-10 parts polysilsesquioxane, and 10-15 parts polyamine curing agent.

[0029] In this disclosure and possible embodiments, the unsaturated hydrocarbon-terminated polysilsesquioxane is a cage-like polyhedral oligomeric silsesquioxane, having a closed cage-like inorganic core formed by Si-O-Si bonds, with one or more of methacryloxy, acryloyloxy, and methacrylamide groups bonded to the outer surface of the cage core, and the structure being regular T B The structure is predominantly cage-like; its branching degree is 6-8, its number-average molecular weight (Mn) is 800-1200 g / mol, its silicon content is 12-18 wt%, its double bond retention rate is ≥90%, and its volatile matter is ≤1.0 wt%. A preferred method for preparing the cage-like polyhedral oligomeric silsesquioxane includes: One or more of methacryloylsilane, acrylic silane, and methacrylamide triethoxysilane are mixed evenly with tetramethylammonium hydroxide pentahydrate and isopropanol, and the silane monomers are hydrolyzed and gradually condensed to prepare the silane with a molecular size of 1.0 to 3.0 nm.

[0030] In this disclosure and possible embodiments, the unsaturated glycidyl ester type epoxy monomer is selected from one or more of diglycidyl diacrylate and its epoxy derivatives, 4-hydroxybutyl acrylate glycidyl ester and its epoxy derivatives, tetrahydrophthalic acid diglycidyl ester and its epoxy derivatives, and glycidyl itaconic acid ester and its epoxy derivatives. Preferably, the epoxy derivative of the glycidyl itaconic acid ester is glycidyl itaconic acid ester diepoxide, and its preparation method is: using glycidyl itaconic acid ester as raw material, PW 12 Using SBA-15 as a heterogeneous catalyst, anhydrous acetonitrile as a solvent, and hydrogen peroxide as an oxidant, the glycidyl itaconic acid ester diepoxide was prepared via a selective epoxidation reaction; a further preparation method is as follows: In a dry reaction vessel, glycidyl itaconic acid ester (raw material) and anhydrous acetonitrile (solvent) are added sequentially and stirred until homogeneous. Then, PW12 / SBA-15 catalyst is added to ensure uniform dispersion of the catalyst in the system. Hydrogen peroxide (oxidant) is slowly added dropwise to the above mixed reaction solution at a reaction temperature of 30-60℃ with stirring for 30-60 min. After the addition is complete, the reaction is carried out at a constant temperature with stirring for 4-8 h. During this period, the reaction progress is monitored by TLC thin-layer chromatography until the raw material spots completely disappear. The reaction is then stopped, and the reaction products are post-processed and separated to obtain the target product.

[0031] In this disclosure and possible embodiments, the polyamine curing agent is selected from one or more of isophorone diamine, 1,3-cyclohexanediamine, 2,4-diaminotoluene, 2,4-p-phenylenediamine, 4,4'-diaminodiphenylmethane, and 4,4'-diaminodiphenyl sulfone.

[0032] In this disclosure and possible embodiments, the method for uniformly mixing the unsaturated glycidyl ester type epoxy monomer, the unsaturated hydrocarbon-terminated polysilsesquioxane, and the polyamine curing agent is as follows: after uniformly mixing the epoxy monomer and the polysilsesquioxane at 25~40°C, a homogeneous premixed adhesive is obtained by vacuum degassing; the polyamine curing agent is added to the homogeneous premixed adhesive, dispersed uniformly, and vacuum degassed again to obtain the epoxy composite premixed system.

[0033] In this disclosure and possible embodiments, the method for sequentially heating and curing the epoxy composite premix system is as follows: after curing at 60~150℃ for 6~8 h, light curing is performed at room temperature for 10 min.

[0034] The following are preferred embodiments of this disclosure.

[0035] In the following embodiments, viscosity was tested according to GB / T2794-2013 standard, tensile properties were tested according to GB / T2567-2021 standard, and glass transition temperature ( T g The degradation performance was obtained by dynamic mechanical thermal analyzer (DMA). The specific testing method was as follows: the degradation experiment was carried out under constant temperature conditions of 80℃. The cured polymer sample was placed in an alcohol / weak base composite depolymerization system and stirred at constant temperature. Samples were taken at different degradation time points. Example 1

[0036] In this embodiment, glycidyl itaconic acid ester and isophorone diamine were purchased from Tianjin Xiens Biochemical Technology Co., Ltd., and acrylate silane, tetramethylammonium hydroxide pentahydrate and isopropanol were purchased from Beijing Inokai Reagent Co., Ltd.

[0037] The specific details of this embodiment are as follows: (1) Synthesis of glycidyl itaconic acid ester diepoxide ① Reaction system setup: Add a mechanical stir bar to a 5000 mL three-necked flask, add 172 g (1000 mmol) of glycidyl itaconic acid ester and 1000 mL of anhydrous acetonitrile, start mechanical stirring, and after complete dissolution, add Keggin-type phosphotungstic acid supported mesoporous silica SBA-15 catalyst (PW). 12 Take 8 g of the / SBA-15 catalyst and stir for 15 minutes to disperse the catalyst evenly, thus obtaining a mixed reaction solution.

[0038] ② Epoxidation reaction: Heat the above mixed reaction solution to 60°C and slowly add 136 g (1200 mmol) of 30% hydrogen peroxide aqueous solution through a constant pressure dropping funnel under normal pressure, controlling the dropping rate, and complete the addition within 2 hours; after the addition, maintain a constant temperature of 60°C and stir for 7 hours, monitor the reaction using TLC thin-layer chromatography, and stop the reaction when the raw material spots completely disappear.

[0039] ③ Catalyst recovery and quenching: Cool the reaction product to room temperature, filter and recover the catalyst, and combine the reaction mother liquor and catalyst washing liquid; add saturated sodium sulfite solution under ice bath to quench excess hydrogen peroxide until the starch-KI test paper does not turn blue.

[0040] ④ Post-treatment and purification: The organic phase was separated by liquid-liquid extraction, washed twice with saturated sodium bicarbonate solution (500 mL each time) and once with saturated sodium chloride solution (500 mL each time), dried over anhydrous magnesium sulfate for 6 hours, filtered, and the solvent was removed by rotary evaporation. The solution was purified by column chromatography to obtain a colorless, transparent, viscous liquid, which is the difunctional epoxy monomer (glycidyl itaconic acid ester diepoxide), with an epoxy value of 0.58–0.66 eq / 100 g and a viscosity (25℃) of 50–200 mPa·s.

[0041] The monomer structure of this glycidyl itaconic acid ester diepoxide has active epoxypropyl groups (-CH(O)CH-CH2O-) at both ends, which can be cured with amines, acid anhydrides, and phenols. The molecule contains unsaturated C=C double bonds (itaconic acid skeleton), and has dual reactivity of epoxy and double bonds.

[0042] (2) Synthesis and preparation of acrylic acid-terminated polysilsesquioxanes ① Add 80-100 mL of anhydrous isopropanol to a three-necked flask, add 1 g of tetramethylammonium hydroxide pentahydrate, stir to dissolve, then add 20 g of acrylate silane and 3 g of methyltriethoxysilane (to control the degree of branching), stir at room temperature for 30 min to form a homogeneous silane solution. ② Add deionized water slowly to the system at a ratio of 1.0:1.6 (total molar number of silane monomers: water), and stir the reaction at room temperature for 4 h to allow the silane monomers to be fully hydrolyzed (Si-OC2H5→Si-OH). ③ Heat to 80℃, stir and react at a constant temperature for 10 h, and keep under reflux to prevent solvent evaporation; ④ After the reaction was completed, the product was cooled to room temperature, dispersed in petroleum ether, sonicated for 30 min, and after standing, the supernatant was taken. The petroleum ether was removed by vacuum distillation, and the product was dried under vacuum (60℃, 10 h) to obtain acrylic acid-terminated POS pure product with a branching degree of 6, a number-average molecular weight Mn = 1300 g / mol, an epoxy equivalent of 2.17 eq / 100 g, a double bond content of 4.6 mmol / g, and a viscosity (25℃) of 6700 mPa·s.

[0043] The acrylic-terminated polysilsesquioxane molecule has a star-shaped highly branched topology, with the double bonds in a latent end-capped state. It is stable at room temperature and can participate in cross-linking reactions efficiently when initiated by light.

[0044] (3) Super toughness, high T g Preparation of degradable epoxy resins ① Raw material composition: By mass, the proportions of each component are as follows: 95g glycidyl itaconic acid ester diepoxide, 5g acrylic acid-terminated polysilsesquioxane, and 12g isophorone diamine.

[0045] ②Specific preparation steps: Glycidyl itaconic acid ester diepoxide and acrylic acid-terminated polysilsesquioxane were placed in a three-necked flask, stirred at 30°C and 400 r / min for 45 min, and degassed under a vacuum of -0.095 MPa for 15 min to obtain a premixed adhesive solution. Isophorone diamine was added to the premixed adhesive solution, and the mixture was stirred at 25°C and 900 r / min for 8 min. The mixture was then degassed under a vacuum of -0.095 MPa for 8 min to obtain the epoxy composite premixed system.

[0046] Rheological tests were conducted on the epoxy composite premix system, such as... Figure 1 a\b indicates that the epoxy composite premixed system exhibits typical Newtonian fluid behavior, a wide processing window, and excellent flowability.

[0047] The epoxy composite premix system was injected into a polytetrafluoroethylene mold and cured at room temperature (80°C) for 6 hours, followed by room temperature light curing for 10 minutes (the light source was a 365 nm UV-LED with a light intensity of 500 mW / cm²). After demolding, an epoxy resin product without bubbles or cracks was obtained.

[0048] (4) Performance testing of epoxy resin ① Passed the DMA test ( Figure 2 The glass transition temperature of the resin was obtained. T g The temperature is 247℃, which is higher than that of pure E51 epoxy products. T g(≈95℃) Increased by 125%.

[0049] ② Tensile test ( Figure 3 The results showed that the resin had a tensile strength of 181 MPa, an elongation at break of 6.9%, a fracture toughness (KIC) of 2.2 MPa·m^(1 / 2), a shear strength of 20.4 MPa, and a crosslinking density of 4.0 × 10⁻⁶. -4 mol / cm³; and multiple batch tensile tests have been conducted to prove its batch performance stability.

[0050] ③ Figure 4 a\b\c In-situ stretching negative staining transmission electron microscopy (TEM) and X-ray scattering curves ( Figure 5 This study confirms that a uniformly distributed nanoscale core-shell structure phase (core ≈ 20 nm, core + shell ≈ 25.5 nm) is formed in the resin matrix, and it preferentially bears stress during the in-situ stretching of the resin. Under the action of external force, the nanoscale phase deforms along the direction of force, changing from a spherical shape to an elliptical shape, thereby dissipating internal stress and ultimately improving strength, elongation at break and toughness.

[0051] ④ Degradation test: The product was placed in a sodium carbonate aqueous solution with pH=12 and stirred at 60℃ for 5 days, and the depolymerization rate of the material was 92%; it was placed in a hydrochloric acid aqueous solution with pH=2 and stirred at 70℃ for 7 days, and the depolymerization rate of the material was 89%. Example 2

[0052] In this embodiment, trimethylolpropane tris(3,4-epoxycyclohexylcarboxylate), 4-hydroxybutyl acrylate glycidyl ester, and 1,3-cyclohexanediamine were purchased from Tianjin Xiens Biochemical Technology Co., Ltd., while acrylate silane, tetramethylammonium hydroxide pentahydrate, and isopropanol were purchased from Beijing Inokai Reagent Co., Ltd.

[0053] This embodiment features ultra-toughness and high strength. T g The epoxy resin that can be degraded as needed is composed of the following components by mass: 40 parts of trimethylolpropane tris(3,4-epoxycyclohexylcarboxylate), 50 parts of 4-hydroxybutyl acrylate glycidyl ester modified epoxy monomer, 10 parts of acrylic-terminated polysilsesquioxane (branching degree 8, number average molecular weight 2000 g / mol) prepared according to the method of Example 1, and 10 parts of 1,3-cyclohexanediamine.

[0054] The preparation method is the same as in Example 1.

[0055] Performance testing: T gAt 225℃, the tensile strength is 180.8 MPa, the elongation at break is 7.52%, the shear strength is 19.9 MPa, and the crosslinking density is 3.8 × 10⁻⁶. -4 mol / cm³; placed in a potassium carbonate aqueous solution at pH=13, and degraded by stirring at 50℃ for 5 days, with a depolymerization rate of 88%. Example 3

[0056] In this embodiment, 4-hydroxybutyl acrylate glycidyl ester and 2,4-diaminotoluene were purchased from Tianjin Xiens Biochemical Technology Co., Ltd., and methacrylate silane, tetramethylammonium hydroxide pentahydrate and isopropanol were purchased from Beijing Inokai Reagent Co., Ltd.

[0057] This embodiment features ultra-toughness and high strength. T g The epoxy resin that can be degraded as needed is composed of the following components by mass: 95 parts of diglycidyl tetrahydrophthalate modified epoxy monomer, 6 parts of JB-POS (number average molecular weight 3000 g / mol) with a branching degree of 8, and 15 parts of 2,4-diaminotoluene.

[0058] The preparation method is the same as in Example 1.

[0059] Performance testing: T g At 227℃, the tensile strength is 177.7 MPa, the elongation at break is 7.32%, the shear strength is 19.5 MPa, and the crosslinking density is 3.6 × 10⁻⁻⁻⁶. 4 mol / cm³; placed in a methanol-dibutyltin dilaurate alcoholysis system, and degraded by stirring at 80℃ for 6 days, with a depolymerization rate of 90%.

[0060] Comparative Example 1 The difference between this comparative example and Example 1 is that the preparation method is as follows: the epoxy composite premix system is injected into a polytetrafluoroethylene mold and cured at room temperature for 10 min (the light source is a 365 nm UV-LED with a light intensity of 500 mW / cm²); then cured at 80℃ for 6 h, and after demolding, an epoxy resin product without bubbles or cracks is obtained.

[0061] Performance testing: T g At 175℃, the tensile strength was 108.7 MPa, the elongation at break was 3.1%, the fracture toughness was 0.5 MPa·m^(1 / 2), and the shear strength was 8.9 MPa, indicating severe macroscopic phase separation. Degradation test: At 60℃ and pH=12, sodium hydroxide degradation for 5 days showed a depolymerization rate of 95%, but the mechanical properties during service cannot meet the requirements of high-end applications.

[0062] Comparative Example 2 The difference between this comparative example and Example 1 is that the preparation method is as follows: the epoxy composite premix system is injected into a polytetrafluoroethylene mold, and after being cured in stages at 80℃ / 1 h and 120℃ / 2 h (without light curing process), epoxy resin products without bubbles and cracks are obtained after demolding.

[0063] Performance testing: T g At 168℃, the tensile strength was 132.2 MPa, the elongation at break was 4.1%, the fracture toughness was 0.7 MPa·m^(1 / 2), and the shear strength was 14.2 MPa. Monomer swelling within the epoxy network did not form a core-shell structure. Degradation test: At 60℃ and pH=12, sodium hydroxide degradation for 5 days showed a depolymerization rate of 95%, but the mechanical properties during service do not meet the requirements of high-end applications.

[0064] Comparative Example 3 The difference between this comparative example and Example 1 is that the degree of branching of the acrylic-terminated polysilsesquioxane is 1.

[0065] Performance testing: T g At 142℃, the tensile strength was 97.2 MPa, the elongation at break was 1.5%, and the shear strength was 3.9 MPa, which are significantly lower than those of Example 1. Degradation test: At 60℃ and pH=12, sodium hydroxide degradation for 7 days resulted in a depolymerization rate of 95%, but the mechanical properties during service cannot meet the requirements of high-end applications.

[0066] Comparative Example 4 This comparative example uses commercially available glycidyl ester epoxy cage-type silsesquioxane (brand name GPOSS) to compound bisphenol A type epoxy resin to prepare epoxy resin material. The epoxy group POSS has a conventional octafunctional cage structure, without double bonds, branched topology design, or urethane structure. The system has a processing viscosity of 36.25 Pa s.

[0067] Curing and molding: Since it does not contain double bonds, only the same heating and curing process (homogeneous reaction) is used, and no core-shell structure phase is generated in the system.

[0068] Degradation performance: The system is mainly based on traditional irreversible cross-linking, without dynamic ester bonds and hydrogen bonds working together, and cannot achieve mild degradation.

[0069] Mechanical and thermal properties: tensile strength 93 MPa, glass transition temperature ( T g The temperature range is 134~148℃, and the overall performance is lower than that of the acrylic-terminated polysilsesquioxane modified system with a branching degree of 6 in Example 1.

[0070] Comparative Example 5 This comparative example uses a commercially available silicone-acrylate core-shell toughening agent (PDMS core - PMMA shell, brand: Silquest Q9-6506) compounded with bisphenol A epoxy resin (brand: E51) to prepare an epoxy resin material. The core-shell particles have a flexible polysiloxane core and a polyacrylate shell, with only double-bonded functional groups on the surface, no branched topology, and interfacial issues with epoxy. However, because it is a solid powder, it has poor compatibility with the epoxy system, is difficult to disperse, and often forms a significant phase separation structure.

[0071] Curing and molding: The same process as in this invention is used. The system relies solely on epoxy groups to construct a traditional irreversible cross-linked network, lacking dynamic bonding and hydrogen bond reinforcement. The cross-linking uniformity is generally poor, and the interfacial bonding force is weak.

[0072] Recycling performance: The material contains only traditional ether cross-linked structures and has no dynamic covalent bonds, making it unable to undergo gentle degradation.

[0073] Mechanical and thermal properties: Tensile strength: 99 MPa; Glass transition temperature ( T g ): 96.8 ℃. Because the core-shell particles are added directly, they do not participate in the cross-linking reaction and have an interface with the epoxy resin. Therefore, the network is diluted. Although the toughness is improved, the heat resistance and strength are inevitably sacrificed.

[0074] The crosslinking density, modulus, and high-temperature stability are all significantly lower than those of the JB-POS modified system of this invention.

[0075] In summary, this invention is the first to propose and realize the construction of JB-POS in-situ nano-core-shell structure phases. Without adding core-shell particles or physical blending, a nano-core-shell structure with a flexible core of "molecular cages" and a double-bond-epoxy crosslinking network as the shell is directly generated in-situ during the crosslinking and curing process in one step. The phase regions are uniform in size, exhibit strong interfacial bonding, and are free of aggregation. The core-shell structure drives "strong and tough high..." T g - Stability is achieved through a three-pronged approach: the core provides load-bearing capacity and rigidity enhancement, while the shell provides toughness and interfacial bonding. In-situ anchoring addresses common industry issues such as poor compatibility, uneven phase separation, and decreased heat resistance. The core-shell structure coupled with dynamic bonds enables controllable degradation: core-shell disintegration and bond breakage occur simultaneously, resulting in more thorough degradation, easier recycling, stability in normal environments, and degradation under controlled conditions, truly achieving "on-demand degradation."

[0076] The ultra-tough and high-strength material prepared by this invention T gThis biodegradable epoxy resin boasts a glass transition temperature ≥210℃, tensile strength ≥180 MPa, elongation at break ≥6%, and shear strength ≥19.5 MPa. Its strength and fracture toughness are improved by 220% and 80% respectively compared to pure epoxy systems. It combines high heat resistance, strong mechanical toughness, excellent chemical stability, and biodegradability, addressing the core technical challenges of traditional epoxy resins. Its preparation method is simple, easily scaled up industrially, and uses environmentally friendly raw materials. This epoxy resin can be widely used in electronic device structural components, lightweight aerospace parts, high-end equipment adhesive layers, and composite matrix materials. It is particularly suitable for disposable structural components and recyclable consumables requiring high heat resistance and toughness, and necessitating recycling. It meets the performance requirements of high-end manufacturing while solving the environmental problems associated with epoxy resin waste, demonstrating significant industrial application value and market potential.

[0077] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A super-tough, high-strength T g Furthermore, the method for preparing controllably degradable thermosetting epoxy resin is characterized by, include: Unsaturated glycidyl ester type epoxy monomer, unsaturated hydrocarbon-terminated polysilsesquioxane and polyamine curing agent are uniformly mixed to obtain an epoxy composite premix system; the epoxy composite premix system is then subjected to heat curing and light curing in sequence to obtain the epoxy resin. The epoxy resin crosslinking network forms a nano-core-shell phase structure with a cage-like polysilsesquioxane core and an unsaturated double bond copolymer rigid network as the shell.

2. The method for preparing thermosetting epoxy resin according to claim 1, characterized in that, The epoxy composite premix system, by mass parts, has the following component ratios: 100 parts epoxy monomer, 2-10 parts polysilsesquioxane, and 10-15 parts polyamine curing agent.

3. The method for preparing thermosetting epoxy resin according to claim 1 or 2, characterized in that: The core-shell nanostructure has a core diameter of 10–80 nm and a shell thickness of 5–30 nm; and / or, The unsaturated hydrocarbon-terminated polysilsesquioxane is a cage-like polyhedral oligomeric silsesquioxane, having a closed cage-like inorganic core formed by Si-O-Si bonds, with one or more of methacryloyloxy, acryloyloxy, and methacrylamide groups bonded to the outer surface of the cage core, and the structure is regular T B It has a predominantly cage-like structure; its degree of branching is 6-8, its number-average molecular weight (Mn) is 800-1200 g / mol, its silicon content is 12-18 wt%, its double bond retention rate is ≥90%, and its volatile matter is ≤1.0 wt%.

4. The method for preparing the thermosetting epoxy resin according to claim 1 or 2, characterized in that, The method for preparing the cage-like polyhedral oligomeric silsesquioxane includes: One or more of methacryloylsilane, acrylic silane, and methacrylamide triethoxysilane are mixed evenly with tetramethylammonium hydroxide pentahydrate and isopropanol, and the silane monomers are hydrolyzed and gradually condensed to prepare the silane with a molecular size of 1.0 to 3.0 nm.

5. The method for preparing the thermosetting epoxy resin according to claim 1 or 2, characterized in that: The unsaturated glycidyl ester type epoxy monomer is selected from one or more of the following: diglycidyl diacrylate and its epoxy derivatives, 4-hydroxybutyl acrylate glycidyl ester and its epoxy derivatives, diglycidyl tetrahydrophthalate and its epoxy derivatives, and glycidyl itaconic acid ester and its epoxy derivatives; and / or, The polyamine curing agent is selected from one or more of isophorone diamine, 1,3-cyclohexanediamine, 2,4-diaminotoluene, 2,4-p-phenylenediamine, 4,4'-diaminodiphenylmethane, and 4,4'-diaminodiphenyl sulfone.

6. The method for preparing thermosetting epoxy resin according to claim 5, characterized in that: The epoxy derivative of glycidyl itaconic acid ester is a glycidyl itaconic acid ester diepoxide, which is prepared by using glycidyl itaconic acid ester as a raw material, PW 12 / SBA-15 is used as a heterogeneous catalyst, anhydrous acetonitrile is used as a solvent, and hydrogen peroxide is used as an oxidant to prepare the glycidyl itaconic acid ester diepoxide via a selective epoxidation reaction.

7. The method for preparing the thermosetting epoxy resin according to claim 1 or 2, characterized in that, The method for uniformly mixing unsaturated glycidyl ester type epoxy monomer, unsaturated hydrocarbon-terminated polysilsesquioxane, and polyamine curing agent includes: The epoxy monomer and the polysilsesquioxane are uniformly mixed at 25~40°C, and then vacuum degassing is performed to obtain a homogeneous premixed adhesive. The polyamine curing agent is added to the homogeneous premixed adhesive, dispersed evenly, and vacuum degassing is performed again to obtain the epoxy composite premixed system.

8. The method for preparing the thermosetting epoxy resin according to claim 1 or 2, characterized in that, The method for sequentially heating and photocuring the epoxy composite premix system includes: After curing at 60~150℃ for 6~8 h, it is then photocured at room temperature for 10~20 min. The photocuring light source is a 365nm UV-LED with a light intensity of 500 mW / cm².

9. A super-tough, high-strength T g Furthermore, the thermosetting epoxy resin can be controlled to degrade, characterized in that: It is prepared by the method described in any one of claims 1-8.

10. The ultra-tough and high-strength material as described in claim 9 T g Furthermore, controllable degradable thermosetting epoxy resins are used in the preparation of electronic device structural parts, lightweight aerospace components, high-end equipment adhesive layers, and composite material matrices.

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