Self-repairable epoxy-based glass polymer composite material and preparation method thereof

Abstract

The application relates to the technical field of high polymer materials, and discloses a self-repairable epoxy glass high polymer composite material and a preparation method thereof. The composite material is mainly made of bisphenol A type liquid epoxy resin, phenoxy resin, 1,4-benzene diboronic acid, polyoxypropylene diamine, triphenylphosphine, benzyl glycidyl ether and modified 2,4,6-tris(dimethylaminomethyl) phenol macromolecular adduct, and the preparation process comprises resin melting blending, addition prepolymerization, low-temperature reinforcement of a curing agent, vacuum degassing and multi-section gradient temperature curing. The application utilizes the single-functionality benzyl glycidyl ether as a small-molecule active diluent to control the branching degree of a prepolymer system, reduces the material viscosity and avoids the risk of explosive polymerization; meanwhile, the application utilizes reaction induction to generate a micro-phase separation structure, makes the dynamic borate ester bond and the macromolecular catalyst spontaneously enrich at the phase interface, realizes the rapid and efficient repair of a damaged area on the premise of maintaining the overall mechanical strength of the material.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to self-healing epoxy-based glass polymer composite materials and their preparation methods. Background Technology

[0002] Epoxy resin, as an important thermosetting resin, forms a three-dimensional network structure after cross-linking and curing, possessing excellent mechanical properties and dimensional stability. However, it cannot spontaneously heal after physical damage. Glass-like polymers, by introducing dynamic covalent bonds into the cross-linked network, enable the material to undergo topological rearrangement under specific external stimuli, thereby endowing thermosetting materials with malleable and repairable properties.

[0003] However, existing epoxy-based glass polymer materials face several engineering shortcomings in practical applications. There is a trade-off between the material's mechanical strength and its self-healing efficiency. To meet the high mechanical strength requirements of engineering structural components, it is usually necessary to increase the crosslinking density of the material, but this severely restricts the mobility of polymer chain segments. When the degrees of freedom of the chain segments are limited, the dynamic covalent bonds within the network struggle to achieve effective contact and exchange reactions, leading to a significant decrease in the material's self-healing efficiency. Conversely, if the crosslinking density is reduced to increase the mobility of the molecular chains, the overall load-bearing capacity of the material will inevitably be weakened.

[0004] Furthermore, these materials also face significant technological hurdles in large-scale processing. The construction of dynamic covalent bonds and the addition of related catalysts typically alter the reaction kinetics of the original epoxy system. In the actual formulation of high-density crosslinked systems, the prepolymer system often exhibits high initial viscosity and is prone to violent exothermic reactions during mixing and the initial stages of crosslinking. This heat accumulation can easily trigger thermal runaway and explosive polymerization, narrowing the processing window for molding and making it difficult to meet the safety requirements of routine operations such as degassing and infusion in industrial production. Simultaneously, conventional free-state small-molecule amine catalysts are prone to volatilization and physical migration to the matrix surface under high-temperature curing or long-term service conditions. This continuous loss of catalytic components reduces the catalytic concentration within the matrix, thereby weakening the material's ability to repeatedly repair itself after repeated damage. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a self-healing epoxy-based glass polymer composite material and its preparation method, which solves the problems of existing epoxy-based glass polymer materials having difficulty in achieving both mechanical strength and self-healing efficiency, and the high viscosity of the prepolymer system during the preparation process, which easily leads to thermal runaway and explosive polymerization.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a self-healing epoxy-based glass polymer composite material, employing the following technical solution: The self-healing epoxy-based glass polymer composite material is made from the following raw materials in parts by weight: 80-120 parts by weight of bisphenol A type liquid epoxy resin; 10-20 parts by weight of phenoxy resin; 4-8 parts by weight of 1,4-phenylenediboric acid; 19-26 parts by weight of polyoxypropylene diamine; 0.05-0.2 parts by weight of triphenylphosphine; 1.0-2.5 parts by weight of benzyl glycidyl ether; and 1.61-3.43 parts by weight of modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct.

[0007] By employing the above technical solution, this invention achieves synergistic response of multiple components at the design level of material formulation and network structure. Specifically, when 1,4-phenylenediboric acid undergoes ring-opening with bisphenol A type liquid epoxy resin, dynamic borate ester bonds are initially introduced into the system. To avoid excessive crosslinking at this stage, a monofunctional benzyl glycidyl ether is designed to participate in the reaction simultaneously. Because this monofunctional molecule severs part of the polymer chain extension direction at the end group, the average functionality and crosslinking network density of the prepolymer system are reduced. This topological constraint maintains the low viscosity of the fluid in the early stages of processing, thereby providing ample process window for subsequent molding operations.

[0008] As the prepolymer progresses downstream in the curing and crosslinking process, polypropylene diamine begins to add to the remaining epoxy groups, gradually building the main crosslinked network. During this simultaneous crosslinking and curing process, due to the thermodynamic incompatibility between the pre-added phenoxy resin and the molded epoxy network in terms of molecular chain structure, reaction-induced microphase separation occurs within the material. This differentiation of physical morphologies results in the separation of a flexible phase region rich in phenoxy resin and a rigid phase region rich in crosslinked epoxy within the macroscopic composite material.

[0009] To resolve the physical conflict between the high-strength rigid matrix and the dynamic repair phase, this scheme utilizes the objective differences in polarity and reaction kinetics among the components to promote the spontaneous enrichment of dynamic borate ester bonds constructed from 1,4-phenylenediboric acid and modified 2,4,6-tris(dimethylaminomethyl)phenol macroadducts at the interface between these two phases. The tertiary amine structure contained in the modified macroadduct can complex with adjacent boron atoms, thereby directly reducing the activation energy required for the exchange reaction of borate ester bonds. When cracks appear in the material during actual service and are stimulated by an external heat source, the polymer chain movement at the microphase separation interface is activated. Benefiting from the high-concentration catalytic environment in this local region, the borate ester bonds rapidly undergo dynamic exchange, causing the molecular chains at the damaged sites to re-dissociate and recombine to complete the healing. At the same time, the large-area rigid phase framework, being undamaged, still ensures that the material as a whole retains its original mechanical strength.

[0010] Preferably, the bisphenol A type liquid epoxy resin has an epoxy value of 0.51 mol / 100g; the phenoxy resin has a weight-average molecular weight of 30,000-60,000; and the polyoxypropylene diamine has an average molecular weight of 230.

[0011] By adopting the above technical solution, the molecular weight and active group density of the main raw materials were specifically limited. This matching of underlying parameters coordinated the evolution process between crosslinking kinetics and phase separation thermodynamics, enabling the composite material to stably solidify into a bicontinuous microphase separation morphology.

[0012] Preferably, the modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct is a product obtained by ring-opening addition reaction of benzyl glycidyl ether and 2,4,6-tris(dimethylaminomethyl)phenol; specifically, it is prepared by stirring 0.6-1.4 parts by weight of benzyl glycidyl ether and 1.0-2.0 parts by weight of 2,4,6-tris(dimethylaminomethyl)phenol at a constant temperature of 50-70°C for 1.5-3 hours.

[0013] By employing the above technical solution, the original small-molecule catalyst is transformed into a large-molecule form through a ring-opening addition reaction, thus physically avoiding the engineering risks of volatilization or leakage of free small-molecule amines during high-temperature processing. This not only improves the thermal stability of the catalytic component in the epoxy matrix but also further enhances its ability to migrate to the phase boundary and reside therefore for a long time.

[0014] Preferably, the composite material has a dual continuous microphase separation structure, and in the variable temperature scanning test of dynamic thermomechanical analysis, its loss factor curve has independent low-temperature side transition peaks and high-temperature side transition peaks, with the low-temperature side transition peak located between 75 and 92°C and the high-temperature side transition peak located between 130 and 146°C.

[0015] By employing the above technical solution, this characteristic of exhibiting dual glass transition temperatures essentially reflects a stable microphase separation network within the system. The transition peak on the low-temperature side originates from the flexible interface phase rich in dynamic bonds, providing the thermodynamic basis for the material's rapid initiation of a repair response; while the transition peak on the high-temperature side corresponds to the rigid phase of the main cross-linked network, ensuring that the material retains sufficient load-bearing capacity even at normal ambient temperatures.

[0016] Secondly, the present invention provides a method for preparing a self-healing epoxy-based glass polymer composite material, employing the following technical solution: A method for preparing a self-healing epoxy-based glass polymer composite material includes the following steps: S1. A protective gas is introduced into the main reactor, and bisphenol A type liquid epoxy resin and phenoxy resin are added. The mixture is heated and stirred until the solid resin is completely melted to form a homogeneous blend. S2. Cool down the main reactor, add triphenylphosphine, 1,4-phenyldiboronic acid and benzyl glycidyl ether in sequence, stir at constant temperature until the material becomes transparent again, and obtain the terminal epoxy borate ester prepolymer. S3. Cool the main reactor again, add polyoxypropylene diamine and modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct, stir evenly, and then evacuate the system for vacuum degassing. S4. Inject the degassed mixture into the mold, perform gradient heating and curing, and after curing, cool and demold to obtain the self-healing epoxy glass polymer composite material.

[0017] By adopting the above technical solution, this invention achieves a coherent coordination between the preparation process and reaction control. Initially, high-temperature melting is used to achieve molecular-level dispersion of solid phenoxy resin in liquid epoxy, laying a uniform material foundation for subsequent phase separation. Subsequently, under cooling and triphenylphosphine catalysis, regioselective prepolymerization of 1,4-phenylenediboric acid and epoxy resin is initiated. Considering that multifunctional systems are prone to excessive reaction leading to a sharp increase in system viscosity, benzyl glycidyl ether is introduced at this stage for end-group blocking, thereby effectively maintaining the flowability of the prepolymer system. When the system temperature is further reduced, a highly active polyetheramine curing agent is mixed in. This low-temperature feeding combined with vacuum degassing not only significantly suppresses the reaction rate in the initial stage of crosslinking but also removes air bubbles entrained in the system, mitigating the risk of explosive polymerization caused by concentrated heat. Finally, the molded material undergoes multi-stage gradient heating, allowing chemical crosslinking and phase separation to proceed simultaneously. While slowly releasing the internal stress of curing shrinkage, a cured product with a dense internal structure and the target microstructure is obtained.

[0018] Preferably, in step S1, the protective gas is nitrogen or argon, the temperature is raised to 120-140°C, and the constant temperature stirring time is 1-2 hours.

[0019] By adopting the above technical solution, the inert gas introduced isolates the outside air and eliminates the risk of oxidative degradation of polymer chains at high temperatures; at the same time, this specific heating range and constant temperature duration ensure the complete dissolution and fusion of solid resin particles.

[0020] Preferably, in step S2, the temperature of the main reactor is reduced to 80-90°C, and the constant temperature stirring time is 1-2 hours.

[0021] By adopting the above technical solution and controlling the temperature within this specific range, the catalytic efficiency of triphenylphosphine for the addition reaction of epoxy and boric acid is activated, while the uncontrolled cross-linking side reaction of polymer segments induced by high temperature is suppressed, thus ensuring the clarity and uniformity of the prepolymer material.

[0022] Preferably, in step S3, the main reactor temperature is reduced to 40-50℃ before the material is added, and the degassing process control system gauge pressure is between -0.08MPa and -0.095MPa, with a vacuum degassing time of 10-20 minutes.

[0023] By employing the above technical solution, the activity of the primary amine in the curing agent is kept relatively sluggish within a temperature window of 40-50℃, thus enabling the degassing process to be completed smoothly without triggering large-scale exothermic crosslinking. The added negative pressure environment removes air and trace amounts of volatile components mixed into the resin, improving the density of the final cured product.

[0024] Preferably, in step S4, the gradient temperature curing specifically includes three stages: the first stage is to keep the temperature at 70-90℃ for 1.5-3 hours; the second stage is to raise the temperature to 110-130℃ and keep the temperature at 1.5-3 hours; and the third stage is to raise the temperature to 140-160℃ and keep the temperature at 1-2 hours.

[0025] By adopting the above technical solution, the stepped heat treatment logic corresponds to different physical and chemical change requirements. The initial heat preservation stage promotes the smooth addition of amine and epoxy groups and the initial gelation; the subsequent heating process drives the residual secondary amine groups to continue to participate in the reaction, and as the cross-linking network further tightens, the phenoxy resin component undergoes large-scale phase separation driven by thermodynamics; the final high-temperature stage allows the material to complete cross-linking and curing in a state exceeding the glass transition temperature, which not only eliminates the internal stress of molding, but also physically locks the catalyst enrichment state at the phase interface.

[0026] This invention provides a self-healing epoxy-based glass polymer composite material and its preparation method. It possesses the following beneficial effects: 1. This invention introduces monofunctional benzyl glycidyl ether as a small-molecule reactive diluent during the prepolymerization stage, actively consuming some epoxy groups and interrupting excessive chain extension, thereby controlling the branching degree of the prepolymer system at the chemical structure level. This formulation design effectively reduces the overall viscosity of the reactants, suppresses the violent exothermic and explosive polymerization phenomena that are easily triggered during mixing and degassing of high-density crosslinked systems, and thus provides a safe and ample operating window for large-scale molding and processing.

[0027] 2. This invention overcomes the engineering challenge of the mutual constraint between mechanical strength and self-healing efficiency in traditional polymer materials. Utilizing the thermodynamic incompatibility between phenoxy resin and the cured epoxy matrix, a stable microphase separation structure is induced during the curing process. This bicontinuous physical morphology constructs a rigid phase region rich in cross-linked epoxy and a flexible phase region rich in phenoxy resin within the material. While maintaining the overall load-bearing capacity of the material through a rigid framework, the flexible regions provide freedom of movement for chain segments in damaged areas, achieving a balance between strength and repair performance.

[0028] 3. This invention significantly improves the dynamic repair response speed and long-term stability of the material's internal components. Due to differences in molecular polarity and reaction kinetics, the dynamic bonds constructed from 1,4-phenylenediboric acid and the modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct can spontaneously accumulate at the phase separation interface. This locally high-concentration catalytic environment directly reduces the activation energy of the borate ester bond exchange reaction. Furthermore, the macromolecular form obtained through ring-opening addition physically restricts the volatilization and exudation of the catalytic components under high-temperature service conditions, ensuring the material's ability to repeatedly heal after multiple damages. Attached Figure Description

[0029] Figure 1 This is a graph showing the change of the loss factor with temperature in the dynamic thermomechanical analysis of this invention. Figure 2 This is a stress relaxation curve diagram of the present invention; Figure 3 This is a graph showing the evolution of complex viscosity over time according to the present invention; Figure 4 This is the room temperature tensile stress-strain diagram of the present invention; Figure 5 This is a diagram showing the tensile strength repair rate of the present invention. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0032] Bisphenol A type liquid epoxy resin, CAS number 25068-38-6, epoxy value 0.51mol / 100g.

[0033] Phenoxy resin, CAS number 25036-25-3, with a weight-average molecular weight of 30,000 to 60,000.

[0034] 1,4-Phenylatedorboic acid, CAS number 4612-26-4.

[0035] Polypropylene diamine, CAS number 9046-10-0, has an average molecular weight of 230.

[0036] 2,4,6-Tris(dimethylaminomethyl)phenol, CAS number 90-72-2.

[0037] Benzyl glycidyl ether (used in this invention as a small molecule reactive diluent, which competitively consumes crosslinking sites through its monofunctional properties, thereby reducing the spatial topological dimension of the prepolymer network), CAS No. 2930-05-4.

[0038] Triphenylphosphine (which also serves as a catalyst for the prepolymerization of terminal epoxy borosilicate esters and the ring-opening reaction of macromolecular adducts in this invention), CAS No. 603-35-0.

[0039] Preparation Example 1: This preparation example provides a method for preparing a modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct, comprising the following steps: In a premixing tank equipped with a temperature control and stirring device, 1.0 parts by weight of benzyl glycidyl ether, 1.5 parts by weight of 2,4,6-tris(dimethylaminomethyl)phenol, and 0.02 parts by weight of triphenylphosphine were added as catalysts. The stirring was started, and the reaction was carried out at a constant temperature of 60°C for 2 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain a modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct.

[0040] Preparation Example 2: This preparation example provides a method for preparing a modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct, comprising the following steps: In a premixing tank equipped with a temperature control and stirring device, 0.6 parts by weight of benzyl glycidyl ether, 1.0 parts by weight of 2,4,6-tris(dimethylaminomethyl)phenol, and 0.01 parts by weight of triphenylphosphine were added as catalysts. The mixture was stirred and reacted at a constant temperature of 50°C for 3 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain a modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct.

[0041] Preparation Example 3: This preparation example provides a method for preparing a modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct, comprising the following steps: In a premixing tank equipped with a temperature control and stirring device, 1.4 parts by weight of benzyl glycidyl ether, 2.0 parts by weight of 2,4,6-tris(dimethylaminomethyl)phenol, and 0.03 parts by weight of triphenylphosphine were added as catalysts. The stirring was started, and the reaction was carried out at a constant temperature of 70°C for 1.5 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain a modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct.

[0042] Example 1: This embodiment provides a self-healing epoxy-based glass polymer composite material, made from the following raw materials in parts by weight: 100 parts by weight of bisphenol A type liquid epoxy resin, 15 parts by weight of phenoxy resin, 6 parts by weight of 1,4-phenylenediboric acid, 23 parts by weight of polyoxypropylene diamine, 0.1 parts by weight of triphenylphosphine, 2.0 parts by weight of benzyl glycidyl ether, and 2.52 parts by weight of the modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct obtained in Preparation Example 1.

[0043] This embodiment also provides a method for preparing a self-healing epoxy-based glass polymer composite material, including the following steps: S1. Nitrogen gas is introduced into the main reactor for protection. 100 parts by weight of bisphenol A liquid epoxy resin and 15 parts by weight of phenoxy resin are added. Stirring is started and the temperature is raised to 130°C. Stirring is carried out at this temperature for 1.5 hours until the solid resin is completely melted and a transparent homogeneous blend is formed. S2. Reduce the temperature of the main reactor to 85°C, and add 0.1 parts by weight of triphenylphosphine, 6 parts by weight of 1,4-phenyldiboronic acid and 2.0 parts by weight of benzyl glycidyl ether in sequence. Stir at 85°C for 1.5 hours until the suspended powder in the reactor disappears and the material becomes transparent again, thus obtaining the terminal epoxy borate ester prepolymer. S3. Reduce the temperature of the main reactor to 45°C, add 23 parts by weight of polyoxypropylene diamine and 2.52 parts by weight of the modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct obtained in Preparation Example 1, stir evenly, evacuate the system and maintain the gauge pressure at -0.08MPa for vacuum degassing for 15 minutes. S4. Inject the degassed mixture into the mold and place it in an oven for gradient temperature curing: first, keep it at 80℃ for 2 hours, then raise the temperature to 120℃ and keep it for 2 hours, and finally raise the temperature to 150℃ and keep it for 1 hour. After curing, allow it to cool naturally to room temperature in the oven and demold to obtain a self-healing epoxy glass polymer composite material.

[0044] Example 2: This embodiment provides a self-healing epoxy-based glass polymer composite material, made from the following raw materials in parts by weight: 80 parts by weight of bisphenol A type liquid epoxy resin, 20 parts by weight of phenoxy resin, 4 parts by weight of 1,4-phenylenediboric acid, 19 parts by weight of polyoxypropylene diamine, 0.05 parts by weight of triphenylphosphine, 1.0 part by weight of benzyl glycidyl ether, and 1.61 parts by weight of the modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct obtained in Preparation Example 2.

[0045] This embodiment also provides a method for preparing a self-healing epoxy-based glass polymer composite material, including the following steps: S1. Nitrogen gas is introduced into the main reactor for protection. 80 parts by weight of bisphenol A liquid epoxy resin and 20 parts by weight of phenoxy resin are added. Stirring is started and the temperature is raised to 120°C. Stirring is carried out at this temperature for 2 hours until the solid resin is completely melted and a transparent homogeneous blend is formed. S2. Reduce the temperature of the main reactor to 80°C, and add 0.05 parts by weight of triphenylphosphine, 4 parts by weight of 1,4-phenyldiboronic acid and 1.0 parts by weight of benzyl glycidyl ether in sequence. Stir at 80°C for 2 hours until the suspended powder in the reactor disappears and the material becomes transparent again, thus obtaining the terminal epoxy borate ester prepolymer. S3. Reduce the temperature of the main reactor to 40°C, add 19 parts by weight of polyoxypropylene diamine and 1.61 parts by weight of the modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct obtained in Preparation Example 2, stir evenly, evacuate the system and maintain the gauge pressure at -0.09MPa for vacuum degassing for 20 minutes. S4. Inject the degassed mixture into the mold and place it in an oven for gradient temperature curing: first, keep it at 70℃ for 3 hours, then raise the temperature to 110℃ and keep it for 3 hours, and finally raise the temperature to 140℃ and keep it for 2 hours. After curing, let it cool naturally to room temperature in the oven and demold to obtain a self-healing epoxy glass polymer composite material.

[0046] Example 3: This embodiment provides a self-healing epoxy-based glass polymer composite material, made from the following raw materials in parts by weight: 120 parts by weight of bisphenol A type liquid epoxy resin, 10 parts by weight of phenoxy resin, 8 parts by weight of 1,4-phenylenediboric acid, 26 parts by weight of polyoxypropylene diamine, 0.2 parts by weight of triphenylphosphine, 2.5 parts by weight of benzyl glycidyl ether, and 3.43 parts by weight of the modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct obtained in Preparation Example 3.

[0047] This embodiment also provides a method for preparing a self-healing epoxy-based glass polymer composite material, including the following steps: S1. Nitrogen gas is introduced into the main reactor for protection. 120 parts by weight of bisphenol A liquid epoxy resin and 10 parts by weight of phenoxy resin are added. Stirring is started and the temperature is raised to 140°C. Stirring is carried out at this temperature for 1 hour until the solid resin is completely melted and a transparent homogeneous blend is formed. S2. Reduce the temperature of the main reactor to 90°C, and add 0.2 parts by weight of triphenylphosphine, 8 parts by weight of 1,4-phenyldiboronic acid and 2.5 parts by weight of benzyl glycidyl ether in sequence. Stir at 90°C for 1 hour until the suspended powder in the reactor disappears and the material becomes transparent again, thus obtaining the terminal epoxy borate ester prepolymer. S3. Reduce the temperature of the main reactor to 50°C, add 26 parts by weight of polyoxypropylene diamine and 3.43 parts by weight of the modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct obtained in Preparation Example 3, stir evenly, evacuate the system and maintain the gauge pressure at -0.095MPa for vacuum degassing for 10 minutes. S4. Inject the degassed mixture into the mold and place it in an oven for gradient temperature curing: first, keep it at 90℃ for 1.5 hours, then raise the temperature to 130℃ and keep it at 1.5 hours, and finally raise the temperature to 160℃ and keep it at 1 hour. After curing, allow it to cool naturally to room temperature in the oven and demold to obtain a self-healing epoxy glass polymer composite material.

[0048] Comparative Example 1: Compared with Example 1, the difference is that a conventional "one-pot" mixing process is used, in which all raw materials (bisphenol A type liquid epoxy resin, phenoxy resin, 1,4-phenylenediboric acid, polyoxypropylene diamine, triphenylphosphine, benzyl glycidyl ether and modified macromolecular adduct) are added to the reactor at one time for heating and reaction, while the rest are the same.

[0049] Comparative Example 2: Compared with Example 1, the difference is that monofunctional benzyl glycidyl ether is not added in step S2 (i.e., the small molecule active diluent is removed), while the rest are the same.

[0050] Comparative Example 3: Compared with Example 1, the difference is that phenoxy resin is not added in step S1, but the rest are the same.

[0051] Comparative Example 4: Compared with Example 1, the difference is that in step S3, the modified adduct obtained in Preparation Example 1 is not added, but is directly replaced with 1.5 parts by weight of unmodified commercially available 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30) liquid, and 1.0 parts by weight of benzyl glycidyl ether and 0.02 parts by weight of triphenylphosphine are added at the same time, and the rest are the same.

[0052] Test Example 1: The cured substrates obtained in Examples 1, 2, 3 and Comparative Example 3 were mechanically cut and polished to prepare standard rectangular specimens with dimensions of 35mm × 10mm × 3mm. The feed rate was controlled throughout the processing to prevent thermal degradation or pre-activation of the cross-linked network on the sample surface caused by frictional heat.

[0053] A dynamic thermomechanical analyzer was used to perform a variable temperature scanning operation on the test specimen in single cantilever bending mode.

[0054] The loading frequency of the fixture is set to 1Hz, an initial static force of 0.1N is applied, and the dynamic strain amplitude is strictly controlled within the range of 0.05% to ensure that the mechanical response of the material always falls within the linear viscoelastic range of the entire temperature change cycle.

[0055] The test temperature window was selected between 25℃ and 200℃, the programmed heating rate was kept constant at 3℃ / min, and high-purity dry nitrogen gas with a flow rate of 50mL / min was continuously introduced into the test chamber for environmental sealing.

[0056] The raw signals of energy storage modulus and loss factor continuously recorded in the instrument's background are extracted. After smoothing the data, the local maxima on the loss factor curve are picked as the glass transition temperatures of the corresponding microphase regions.

[0057] Table 1. Data on Glass Transition Temperature from Dynamic Thermomechanical Analysis Tests

[0058] Reference Figure 1 , Figure 1 This is a graph showing the dynamic thermomechanical analysis loss factor as a function of temperature in this invention. Based on the data in Table 1, combined with Figure 1The test curves show that the loss factor temperature-dependent scanning curves of the example group exhibit two completely independent relaxation transition regions. Long-term curing kinetics tracking revealed that homogeneous epoxy systems typically exhibit only a single chain segment motion signal across the entire temperature range. The broadened splitting double peaks captured here directly confirm, on a physical scale, the reconstruction of the mesoscopic topology within the resin matrix. The low-temperature side peak near 80°C corresponds to the phenoxy resin phase region rich in flexible polyether structures. As the molecular weight of the epoxy backbone network in the system undergoes a nonlinear surge during the high-temperature curing stage, the sudden drop in mixing entropy disrupts the original thermodynamic equilibrium of the blend. The free-state flexible macromolecular chains are extruded and coiled and folded within the crosslinked main phase, forming a bicontinuous microphase separation structure. The high-temperature side peak captured above 130°C originates from the frictional internal loss during the thawing of the dense epoxy skeleton. Looking back at the test trajectory of Comparative Example 3, the removal of phenoxy resin from the formulation caused the internal network to collapse into an extremely dense single structure. The probe only recorded an isolated rigid phase transition reaction at 153.24℃. This contrast confirms the intervention effect of the phase modifier on the behavior of the curing microenvironment. The spontaneous separation of the micro-phase regions reshapes the physical morphology of the material and has a profound impact on the spatial distribution of dynamic bonds within the system. With the physical advancement of phase separation, the pre-embedded borate ester structure, forced by the polarity difference with the backbone network, migrates and becomes highly enriched in the narrow band-like region at the interface between the two phases. Dense dynamic covalent bond groups reside in the gap space of the phase interface. Combined with the characteristic of the macromolecularization promoter being physically blocked due to its excessively large hydrodynamic volume, these interfaces instantly transform into highly active borate ester exchange reaction channels under the condition that the composite material is damaged and subjected to external thermal stimulation. The core phase region maintains the mechanical baseline required to resist macroscopic deformation, while the active local network recombination at the interface avoids the global etherification and dead crosslinking disaster that is easily triggered by high temperature stimulation, thus laying a practical polymer architecture path for the simultaneous coexistence of carrying and repair functions.

[0059] Test Example 2: The composite materials of Example 1 and Comparative Example 4 after curing were selected and cut into rectangular strips with dimensions of 30mm×8mm×2mm using a CNC machining center. Cooling was used throughout the processing to prevent local overheating from causing the dynamic covalent bonds in the system to dissociate.

[0060] The spline was clamped in the tensile fixture of the dynamic thermomechanical analyzer, and an initial static load of 0.01 N was applied to eliminate the bending deflection of the spline. Then the environmental temperature control chamber was sealed.

[0061] The test temperature gradients were set to 80℃, 100℃, 120℃ and 140℃. After each test temperature reached the set value, it was kept constant for 15 minutes to allow the internal temperature gradient of the sample to reach equilibrium.

[0062] Under constant temperature conditions, a 1% step constant tensile strain is applied to the specimen, and this strain value is controlled within the linear viscoelastic range of the material.

[0063] Record the data on the decay of stress required to maintain constant strain over time. Stop the test when the internal stress drops to 37% of the initial peak stress, and read the corresponding time as the characteristic stress relaxation time.

[0064] Table 2. Stress relaxation time data at different temperatures.

[0065] refer to Figure 2 , Figure 2 This is the stress relaxation curve diagram of the present invention; Based on the data in Table 2, Figure 2 The stress relaxation curves show that the stress relaxation kinetics of the system in Example 1 exhibit a significant temperature dependence. At 80°C, the polymer network requires 8542.6 seconds to dissipate internal stress to the baseline of 37%. This long relaxation time typically corresponds to a frozen state in highly cross-linked topologies during routine rheological testing, where molecular chains are confined to local spaces. When the test temperature is gradually increased to 140°C, the relaxation time of the same sample drops sharply to 58.4 seconds. For conventional thermosetting resins, a simple glass transition process cannot induce a kinetic abrupt change spanning two orders of magnitude; this macroscopic phenomenon directly reflects the accelerated frequency of chemical bond breaking and recombination within the network. By pre-embedding a macromolecularly modified curing accelerator in the resin formulation, the steric hindrance effect introduced by benzyl glycidyl ether forms a physical repulsion layer around the tertiary amine groups at room temperature and lower temperatures. The boron-nitrogen coordination bonds are in a stable state with high activation energy, endowing the material with the essential dimensional stability required for an engineering matrix.

[0066] The study investigated the cause of the dramatic relaxation transition in the system at high temperatures. The continuous injection of heat energy intensified the thermal fluctuations of the polymer chain segments. When the local thermal energy overcame the physical barrier caused by steric hindrance, the boron-nitrogen coordination structure dissociated, exposing the electron-deficient boron atom centers. In this state, the boron ester at the phase interface rapidly underwent transesterification with the adjacent free hydroxyl groups. The rapid decay observed in the stress relaxation test is a macroscopic manifestation of the accelerated execution of this microscopic reversible exchange process.

[0067] In contrast, the data from Comparative Example 4 showed a completely different evolutionary trajectory. The sample using unmodified liquid small-molecule amine accelerators still exhibited a relaxation time as high as 5984.7 seconds under high-temperature excitation at 140℃, indicating the presence of undissipated internal stress within the material. Previous infrared spectral tracking of the small-molecule curing system repeatedly observed that free-state small-molecule amines easily induced disordered etherification side reactions between epoxy and hydroxyl groups during the exothermic curing stage. These irreversible carbon-oxygen covalent bonds generated permanent cross-linking nodes in the backbone network, restricting large-scale slippage of molecular chain segments. The formation of the irreversible cross-linking network crowded out the physical space where dynamic covalent bonds could function, leading to the stagnation of the transesterification reaction. By anchoring the catalytic sites within the confined space of the phase interface through macromolecularization, the large-scale occurrence of side reactions was blocked, providing underlying architectural support for the operation of the dynamic decoupling mechanism within the high-modulus matrix material.

[0068] Test Example 3: Materials were prepared in a reactor according to the formulations and feeding sequence of Example 1, Comparative Example 1, and Comparative Example 2. The initial materials of Example 1 and Comparative Example 2 after sequential mixing in step S2, as well as the initial materials of Comparative Example 1 after mixing, were extracted and transferred to sealed containers for storage.

[0069] The test was conducted using a rotational rheometer with a parallel plate fixture of 25 mm diameter. The collected liquid sample was placed on the lower test plate, the distance between the upper and lower test plates was adjusted to 1 mm, and any excess sample squeezed out from the edge of the fixture was cleaned up.

[0070] The temperature of the rheometer's temperature control chamber was set to 85°C to simulate the thermal environment of the prepolymerization reaction and the casting degassing process.

[0071] The test was started in dynamic small-amplitude oscillation shear mode, with the angular frequency set at 10 rad / s and the strain amplitude controlled at 1%, so that the initial network structure inside the material maintained a linear viscoelastic response during data acquisition.

[0072] Record the evolution of complex viscosity over time, with a maximum test time of 120 minutes. Data acquisition for that group of samples is terminated when the complex viscosity reaches the gel critical value of 10000 Pa·s.

[0073] Table 3. Evolution of complex viscosity of the prepolymer system under isothermal conditions at 85℃

[0074] refer to Figure 3 , Figure 3 This is a graph showing the evolution of complex viscosity over time according to the present invention; Based on the data in Table 3 and Figure 3The curves revealed that the rheological response of the prepolymer under isothermal conditions exhibited significant differences due to the influence of the formulation process. Table 3 shows that the complex viscosity of Comparative Example 1 exceeded the test upper limit of 10000 Pa·s at 30 minutes. In early laboratory scale-up tests, it was observed that when liquid epoxy resin, polyetheramine, and phase-modifying substances were mixed and heated to 85°C, the highly reactive amine and epoxy groups underwent a violent exothermic reaction. The local temperature rise accelerated the formation of the crosslinking network, causing the system viscosity to increase exponentially in a short time and resulting in explosive polymerization and solidification. This viscosity divergence phenomenon indicates that the conventional "one-pot" mixing process is difficult to apply to the preparation of multi-component highly reactive systems, and is prone to material scrap due to the sudden narrowing of the processing window.

[0075] After excluding the influence of mixing time, the rheological data of Comparative Example 2 remained relatively flat initially, but the complex viscosity increased rapidly and exceeded the gel critical value in the 60-90 minute range. During the prepolymerization stage, 1,4-phenylenediboric acid underwent an addition reaction with epoxy groups, exhibiting tetrafunctional crosslinking characteristics. According to the polymer gel network theory, multifunctional monomers can induce the formation of a three-dimensional network in the system even at relatively low conversion rates. Early interweaving of molecular chain segments caused the material to prematurely enter a high-viscosity state. In practice, both Comparative Example 1 and Comparative Example 2 failed to complete subsequent vacuum degassing and mold casting due to loss of flowability, thus preventing the preparation of macroscopic standard samples for subsequent mechanical testing.

[0076] To control the branching degree of the prepolymer network and ensure processability, a monofunctional benzyl glycidyl ether was introduced in Example 1. Test results showed that the complex viscosity of the system remained robustly below 15 Pa·s for 120 minutes, without any abrupt crosslinking signals indicating viscosity abruptness. Benzyl glycidyl ether effectively reduced the average functionality of the system by competitively consuming some open-ring sites, thereby significantly delaying the appearance of the gel point. This structural reduction method allows for a sufficiently extended processing time in the liquid phase, meeting the stringent requirements of industrial fluid transport and molding processes for low-viscosity time windows.

[0077] Test Example 4: Cured boards from Examples 1, 2, 3, and Comparative Example 3 were selected and cut into Type 1B tensile specimens using a CNC machining center in accordance with GB / T1040 standard. The parallel sections of the specimens were sanded along the axial direction with 1000-grit sandpaper to remove machining marks.

[0078] The polished sample was placed in a constant temperature and humidity environment of 25°C and 50% relative humidity for 48 hours to allow the residual stress generated by the machining to fully relax.

[0079] The specimen is clamped in the upper and lower wedge clamps of the universal testing machine. The position is adjusted so that the longitudinal axis of the specimen coincides with the tensile loading axis. A precision extensometer is installed in the gauge length section of the specimen.

[0080] Set the tensile loading rate of the crosshead of the testing machine to 2.0 mm / min, start the program, and synchronously and continuously collect force and deformation data through the sensor.

[0081] The sample was continuously loaded until it fractured. The stress-strain curve was recorded. The maximum tensile stress that the sample was subjected to before fracture was extracted as the tensile strength. The elongation at break was calculated based on the gauge length elongation at fracture.

[0082] Table 4. Test data for room temperature tensile mechanical properties

[0083] refer to Figure 4 , Figure 4 This is the room temperature tensile stress-strain diagram of the present invention; According to Table 4 and Figure 4 The room temperature tensile test results show that the composite material exhibits a strong component-dependent characteristic in terms of macroscopic deformation and load-bearing mechanism. Conventional high-crosslink density pure epoxy-cured networks often exhibit typical glassy brittle fracture due to stress concentration, as confirmed by the test trajectory of Comparative Example 3. After removing the phenoxy resin as a phase modifier, the system completely collapses into a single dense, rigid crosslinked phase; while achieving a peak strength of 92.14 MPa, the elongation at break sharply decreases to 1.76%. This rigid mechanical response means that when the specimen is subjected to an external uniaxial tensile load, the concentrated stress accumulated at internal micro-defects cannot be effectively dissipated, and crack initiation signifies instantaneous instability and penetration. The example group, by precisely setting the proportion of phenoxy resin in the formulation, establishes an elastic adjustment space for strength and toughness. Taking Example 1 as an example, the elongation at break jumps to 6.18%, and the material undergoes an observable yielding energy dissipation process before macroscopic fracture, while the tensile strength remains above the engineering-grade standard of 78.43 MPa. Based on existing phase separation theories, this mechanical transformation combining rigidity and flexibility originates from the differentiated response of a bicontinuous microphase network to external work. Flexible phenoxy phases rich in polyether bonds interweave within the rigid backbone; when the matrix is ​​subjected to forced deformation, the large-volume flexible phase regions function as stress buffers. As microcracks approach the interface between the two phases, the flexible segments are forced to undergo large-scale spatial slippage and orientation, converting the surface energy initiating fracture into intramolecular energy dissipation, forcibly deflecting or blunting the linear crack propagation trajectory. Phase modulators not only provide physical anchors for the enrichment of dynamic covalent bonds at interfaces but also inject a dissipation mechanism into the material system to resist external polar damage.

[0084] Test Example 5: Cured boards from Examples 1, 2, and 3, as well as Comparative Examples 3 and 4, were selected and prepared into 1B-type tensile specimens using a machining center. The initial width and thickness of the working section were measured.

[0085] The specimen was fixed on a cutting fixture equipped with a local temperature control device. According to the glass transition temperature of each group of specimens, the hot air circulation was turned on to raise the temperature of the central area of ​​the gauge section to near its softening point (Examples 1-3 and Comparative Example 4 were raised to 90°C, and Comparative Example 3 was raised to 160°C), so that the flexible phase region with low crosslinking density softened locally beyond the glass transition temperature.

[0086] After the sample softens locally, use a single-edged blade with a thickness of 0.1 mm to apply vertical pressure to the softened area and cut the sample flat, avoiding brittle fracture and damage to the interface quality caused by direct cutting at room temperature.

[0087] Place the two ends of the cut sample into a polytetrafluoroethylene butt mold to ensure a tight fit between the cut surfaces. Apply a horizontal thrust of 0.05 MPa to both ends of the sample and transfer the entire sample, including the mold, into a forced-air drying oven.

[0088] Set the drying oven temperature to 140℃ and maintain the temperature for 2 hours.

[0089] After the repair procedure was completed, the sample was slowly cooled to room temperature in the chamber and placed in an environment of 25°C and 50% relative humidity for 24 hours to adjust the humidity.

[0090] The repaired specimen was subjected to a second tensile test using a universal testing machine at a tensile rate of 2.0 mm / min. The peak stress at which the specimen broke for the second time was recorded, and the self-repair efficiency was calculated using the ratio of this stress to the original strength.

[0091] Table 5. Test data on heat-stimulated self-healing performance.

[0092] refer to Figure 5 , Figure 5 This is a diagram showing the tensile strength repair rate of the present invention; According to Table 5 and Figure 5The recorded thermally stimulated self-healing behavior revealed differences in the underlying chemical structure between the various sample groups in terms of physical recombination and mechanical recovery capabilities. The example group exhibited excellent structural reconstruction efficiency, with Example 1 showing a post-repair strength recovery of 71.85 MPa and an absolute repair efficiency as high as 91.61%. In previous follow-up studies on the self-healing process of high-modulus resins, the strength recovery after physical contact at the fracture surface was often severely limited by insufficient chain segment mobility; however, the leap in macroscopic healing efficiency in this scheme is directly related to the deep coupling between the pre-set mesoscopic topology and environmental response chemistry. When the system is subjected to an external thermal field of 140°C, the steric hindrance effect surrounding the macromolecularization promoter is temporarily broken by the intense thermal fluctuations of the polymer chains, and the boron-nitrogen coordination bonds that were originally trapped in the activation potential trap are re-dissociated. Thanks to the artificially induced phase separation mechanism in the previous curing process, a large number of dynamic borate ester groups have already accurately migrated and accumulated in the microphase interface region. At the moment the cut surfaces overlap under pressure, the high density of free hydroxyl groups at the interface and the exposed electron-deficient boron atoms trigger a high-frequency boron ester exchange reaction within an extremely narrow three-dimensional space. The interfacial molecular chains in the thawed state cross the physical cut and re-interweave, and the regenerated covalent network heals the macroscopic crack at the microscale in a zipper-like manner. Crucially, this recombination behavior is strictly confined to the vicinity of the phase interface, and the supporting framework of the rigid epoxy network is not degraded due to local topological rearrangement.

[0093] Comparative Example 3, lacking the phase-regulating underlying layer, completely lost its repair activity under the same thermal stimulation environment, with a repair efficiency of only 13.51%. Within the homogeneous and dense three-dimensional epoxy framework, dynamic borate ester bonds are forced into a disordered and randomized state. When the material fractures, the number of newly exposed chemical sites with interfacial activity is sparse, and the extremely high cross-linking topology blocks the long-range diffusion path of the polymer chain at 140℃, resulting in neither physical entanglement nor chemical bonding at the two ends of the cross-section. The data from Comparative Example 4 exposes the fatal flaws of traditional small molecule catalysts in the development of dynamic networks from another perspective. When the system degrades to using unmodified conventional DMP-30, the repair efficiency drops to a minimum of 8.26%. Free small molecule amines readily undergo long-range migration within the resin matrix during the mixing, casting, and heating stages, thereby inducing disordered etherification reactions between epoxy and hydroxyl groups. This irreversible byproduct network is like cement cast around the dynamic bonds, permanently locking the physical space for chain segment activity and excessively consuming potential catalytic active centers. Small molecule catalytic systems lacking steric anchoring protection cannot maintain sufficient activity to initiate late-stage healing in multi-component reaction fields. This demonstrates that modifying catalysts through macromolecular addition to construct steric locking mechanisms is an inevitable path to achieve intelligent upgrading of thermosetting resins.

[0094] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A self-healing epoxy-based glass polymer composite material, characterized in that, Made from the following parts by weight of raw materials: 80-120 parts by weight of bisphenol A type liquid epoxy resin; 10-20 parts by weight of phenoxy resin; 4-8 parts by weight of 1,4-phenylenediboric acid; 19-26 parts by weight of polypropylene diamine; Triphenylphosphine 0.05-0.2 parts by weight; 1.0-2.5 parts by weight of benzyl glycidyl ether; 1.61-3.43 parts by weight of modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct.

2. The self-healing epoxy-based glass polymer composite material according to claim 1, characterized in that, The specific parameters of the raw materials are as follows: The bisphenol A type liquid epoxy resin has an epoxy value of 0.51 mol / 100g; The weight-average molecular weight of the phenoxy resin is 30,000-60,000. The average molecular weight of the polyoxypropylene diamine is 230.

3. The self-healing epoxy-based glass polymer composite material according to claim 1, characterized in that, The modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct is a product obtained by the ring-opening addition reaction of benzyl glycidyl ether and 2,4,6-tris(dimethylaminomethyl)phenol under the action of a catalyst.

4. The self-healing epoxy-based glass polymer composite material according to claim 3, characterized in that, The modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct was prepared from raw materials comprising the following parts by weight: 0.6-1.4 parts by weight of benzyl glycidyl ether; 1.0-2.0 parts by weight of 2,4,6-tris(dimethylaminomethyl)phenol; Triphenylphosphine 0.01-0.03 parts by weight; The modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct is prepared by adding the above raw materials to a premix tank equipped with a temperature control and stirring device, using triphenylphosphine as a catalyst, and stirring the reaction at a constant temperature of 50-70℃ for 1.5-3 hours.

5. The self-healing epoxy-based glass polymer composite material according to any one of claims 1-4, characterized in that, The composite material has a dual continuous microphase separation structure. In the variable temperature scanning test of dynamic thermomechanical analysis, its loss factor curve has independent low-temperature side transition peaks and high-temperature side transition peaks. The low-temperature side transition peak is located between 75 and 92°C, and the high-temperature side transition peak is located between 130 and 146°C.

6. A method for preparing a self-healing epoxy-based glass polymer composite material, characterized in that, The method for preparing the self-healing epoxy-glass polymer composite material according to any one of claims 1-5 comprises the following steps: S1. A protective gas is introduced into the main reactor, and bisphenol A type liquid epoxy resin and phenoxy resin are added. The mixture is heated and stirred until the solid resin is completely melted to form a homogeneous blend. S2. Cool the main reactor, add triphenylphosphine, 1,4-phenyldiboronic acid and benzyl glycidyl ether in sequence, stir at constant temperature until the material becomes transparent, and obtain the terminal epoxy borate ester prepolymer. S3. Cool the main reactor again, add polyoxypropylene diamine and modified 2,4,6-tris(dimethylaminomethyl)phenol macromolecular adduct, stir evenly, and then evacuate the system for vacuum degassing. S4. Inject the degassed mixture into the mold, perform gradient heating and curing, and after curing, cool and demold to obtain the self-healing epoxy glass polymer composite material.

7. The method for preparing the self-healing epoxy-based glass polymer composite material according to claim 6, characterized in that, In step S1, the protective gas is nitrogen or argon, the temperature is raised to 120-140℃, and the constant temperature stirring time is 1-2 hours.

8. The method for preparing the self-healing epoxy-based glass polymer composite material according to claim 6, characterized in that, In step S2, the temperature of the main reactor is reduced to 80-90℃, and the constant temperature stirring time is 1-2 hours.

9. The method for preparing the self-healing epoxy-based glass polymer composite material according to claim 6, characterized in that, In step S3, the main reactor temperature is reduced to 40-50℃ before the material is added, and the degassing process control system gauge pressure is between -0.08MPa and -0.095MPa, with vacuum degassing time being 10-20 minutes.

10. The method for preparing the self-healing epoxy-based glass polymer composite material according to claim 6, characterized in that, In step S4, the gradient temperature curing specifically includes three stages: First stage: Keep warm at 70-90℃ for 1.5-3 hours; Second stage: Raise the temperature to 110-130℃ and keep it warm for 1.5-3 hours; Third stage: Heat to 140-160℃ and keep warm for 1-2 hours.

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