A reworkable epoxy-based glassy polymer material and a preparation method thereof

Abstract

This invention relates to the field of polymer materials technology, and discloses a reprocessable epoxy-based glass polymer material and its preparation method. The material comprises bisphenol F epoxy resin, phenyl glycidyl ether, triethylenetetramine, 1,4-phenylenediboric acid, and anhydrous zinc chloride or anhydrous ferric chloride. In the system, bisphenol F epoxy resin and triethylenetetramine crosslink to form a rigid main framework; phenyl glycidyl ether introduces suspended segments to reduce steric hindrance; 1,4-phenylenediboric acid constructs a dynamically covalent network with interface reconstruction; and metal salts form a physical coordination network that inhibits segment slip at room temperature. The preparation method includes steps such as prepolymerization, azeotropic dehydration condensation, metal coordination, and phase separation precipitation hot pressing. This invention constructs an epoxy-boronate hybrid network, enabling the material to possess high elastic modulus and fracture strength at room temperature, while allowing for pulverization and reprocessing through topological exchange of dynamic bonds under heating conditions at 100°C.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a reprocessable epoxy-based glass polymer material and its preparation method. Background Technology

[0002] Epoxy resins are widely used in industrial manufacturing and composite materials due to their excellent mechanical strength, dimensional stability, and chemical resistance. However, traditional epoxy resins form a permanent three-dimensional cross-linked covalent network after curing, making it impossible to reprocess, weld, repair, or chemically recycle the material after it is damaged or reaches the end of its service life. This results in significant resource waste and environmental pressure.

[0003] To address the inherent limitations of thermosetting materials, existing technologies have introduced dynamic covalent bonds into polymer networks, developing glass-like polymers. Under specific temperature stimuli, these materials undergo topological exchange reactions of the internal dynamic covalent bonds, endowing the cross-linked network with rheological and remodeling capabilities. However, in practical systems, a difficult-to-reconcile contradiction exists between high strength and high dynamic exchange efficiency.

[0004] To maintain the high mechanical strength required for epoxy resin as a load-bearing material, a high crosslinking density is typically necessary. This rigid framework with high crosslinking density generates a strong steric hindrance effect, severely restricting the freedom of movement of macromolecular chain segments and hindering the dissociation and recombination of dynamic covalent bonds. At a macroscopic level, the cross-sectional interface of the material struggles to achieve interdiffusion and deep entanglement of polymer chains under conventional heat treatment conditions, resulting in low dynamic exchange efficiency, excessively high required temperatures, or excessively long repair times. Conversely, reducing the crosslinking density to increase the mobility of molecular chain segments and promote welding fusion directly leads to a significant decrease in the material's elastic modulus and tensile strength at room temperature, rendering it unusable as a structural component.

[0005] Furthermore, existing dynamic crosslinking systems also have shortcomings in synthesis and preparation. For example, systems based on borate ester bonds are constrained by the chemical equilibrium of water during condensation reactions, making it difficult to achieve high conversion rates using conventional processes, resulting in incomplete network crosslinking. Simultaneously, polar solvents in the reaction system are often difficult to completely remove during the molding stage. These microstructural defects and the internal plasticizing effect of residual solvents further weaken the material's room-temperature mechanical properties and induce bubbles or pores during thermal processing, ultimately preventing the polymer from achieving ideal reprocessability. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a reprocessable epoxy-based glass polymer material and its preparation method, which solves the problems of difficulty in achieving both high room-temperature mechanical strength and high dynamic exchange efficiency in existing dynamically cross-linked polymer materials, as well as the difficulty in deep fusion of the pulverized and reprocessed interface due to large steric hindrance of the rigid skeleton, microstructural defects and solvent residues.

[0007] To achieve the above objectives, the present invention provides a reprocessable epoxy-based glass polymer material, employing the following technical solution: a reprocessable epoxy-based glass polymer material, which is made from raw materials comprising the following parts by weight: 2.83 to 14.17 parts of bisphenol F type epoxy resin; 2.50 to 12.52 parts of phenyl glycidyl ether; 2.44 parts of triethylenetetramine; 4.14 parts of 1,4-phenylenediboric acid; 0.01 to 0.45 parts of metal salt.

[0008] Among them, bisphenol F epoxy resin undergoes a ring-opening addition reaction with triethylenetetramine to crosslink and form a rigid main framework; The monoepoxy group of phenyl glycidyl ether introduces a suspended chain segment into the main skeleton to reduce steric hindrance around the reaction site; 1,4-Phenylatedorboic acid undergoes condensation with the diol structure generated by the main backbone side chain to construct a thermally reversible dynamic covalent network; Metal ions in metal salts coordinate with heteroatoms in the network to form a physically locked network that inhibits the relative slippage of free chain segments at room temperature.

[0009] By employing the above technical solution, this invention constructs a dual network system combining covalent crosslinking and non-covalent coordination within the material. The system's reaction mechanism and structural evolution process are specifically divided into the following stages: The first stage involves the construction and modification of the basic network. During this reaction, the diepoxy groups at the ends of the bisphenol F epoxy resin and the monoepoxy groups of phenyl glycidyl ether undergo nucleophilic ring-opening addition reactions with the active primary and secondary amine hydrogen atoms contained in triethylenetetramine.

[0010] On the one hand, bisphenol F type epoxy resin crosslinks with multifunctional amines to form a three-dimensional covalent skeleton, giving the material basic load-bearing capacity; On the other hand, phenyl glycidyl ether contains only a single reaction site, forming a suspended side chain with one end free after being integrated into the main network. This suspended structure expands the free volume within the polymer, effectively reducing steric hindrance near the crosslinking nodes. Simultaneously, after ring opening, the epoxy groups generate numerous secondary hydroxyl structures at the skeletal side chain positions.

[0011] The second stage involves the introduction of a dynamic covalent network. The borate groups at both ends of the 1,4-phenylenediboric acid molecule undergo a dehydration condensation reaction with the adjacent secondary hydroxyl groups formed earlier. The reaction is characterized by the dehydration of arylboronic acid with a diol structure to generate arylboronic esters and water molecules. The resulting boronic ester bonds are typical dynamic covalent bonds, exhibiting thermally reversible topological exchange properties. When the material is subjected to a specific heat treatment temperature, the BN coordination bonds dissociate, transforming the two five-membered rings into an eight-membered ring. Subsequently, the boronic esters undergo dynamic exchange between adjacent structures. Due to the low steric hindrance environment created by the dangling side chains, the resistance to interpenetration and diffusion of polymer segments at damaged or broken interfaces is significantly reduced, thereby achieving the crushing and reprocessing of the macroscopic interface.

[0012] The third stage is the anchoring of the physically locked network. Transition metal ions dissociated from the metal salt utilize their empty orbitals to complex with secondary amine nitrogen atoms and ether bond oxygen atoms on the polymer backbone, forming coordination crosslinking nodes. At room temperature, the metal coordination bonds physically anchor the freely moving suspended chain segments, restricting the relative slippage of the free polymer chains, thereby improving the overall elastic modulus and fracture strength of the system. Under heating conditions, the physical coordination bonds dissociate, releasing the mobility of the side chains, and synergistically completing the final interfacial fusion through the exchange reaction of dynamic covalent bonds.

[0013] Preferably, the metal salt is anhydrous zinc chloride or anhydrous ferric chloride. By employing the above technical solution, the electronic structure of zinc or iron ions readily forms stable octahedral or tetrahedral complex centers with nitrogen and oxygen atoms within the system. Using anhydrous metal salts eliminates the introduction of external moisture into the system. The formation of borate ester bonds is a reversible esterification reaction; an increase in moisture would cause the chemical equilibrium to reverse towards dissociation. Strict anhydrous environmental control maintains the forward esterification reaction, ensuring the crosslinking density of the dynamic covalent network.

[0014] Preferably, the molded polymer material exhibits a room-temperature elastic modulus greater than 2.1 GPa and a tensile strength greater than 65 MPa when tested at room temperature (25 degrees Celsius). By adopting the above technical solution, the material's performance indicators can meet the load-bearing requirements of structural components, overcoming the inherent technical defects of conventional dynamic cross-linked polymers, which suffer from lower mechanical properties due to an emphasis on overall flowability and reshaping.

[0015] This invention provides a method for preparing a reprocessable epoxy-based glass polymer material, employing the following technical solution: A method for preparing a reprocessable epoxy-based glass polymer material includes the following steps: A method for preparing a reprocessable epoxy-based glass polymer material includes the following steps: S1. Bisphenol F epoxy resin and phenyl glycidyl ether are added to a mixed solvent and stirred to dissolve; then triethylenetetramine is added and stirred under constant temperature to obtain a skeleton prepolymer solution. S2. Dissolve 1,4-phenylenediboric acid in a solvent and slowly add it dropwise to the above-mentioned skeleton prepolymer solution; heat the system to bring it to a reflux state and continuously remove the condensed water generated in the reaction to carry out the dehydration reaction, and then cool it down; S3. Dissolve the metal salt in an alcohol solvent to form a complexation solution; add the complexation solution dropwise to the reaction system under stirring, and stir at a constant temperature to form metal coordination crosslinking, thereby obtaining a viscous resin solution; S4. The above viscous resin liquid is dropped into a poor solvent for phase separation and precipitation. The precipitated solid particles are collected, washed, and vacuum dried to obtain particle powder. The particle powder is loaded into a mold and hot-pressed and welded to form a shape. After cooling and demolding, the reprocessable epoxy glass polymer material is obtained.

[0016] By employing the above-mentioned technical solution, the preparation process independently implements the construction of the covalent network, the condensation of dynamic esterification bonds, and the metal coordination process step by step. This staged polymerization method avoids chemical interference between different crosslinking mechanisms during the prepolymerization stage. The dehydration reaction disrupts the esterification reaction equilibrium by continuously removing byproduct water, directly driving the reaction forward. Subsequent phase separation and hot pressing operations transform the liquid resin into a high-density solid structure, eliminating the interference of internal solvents on surface remodeling.

[0017] Preferably, in step S1, the mixed solvent is composed of N,N-dimethylformamide and toluene in a volume ratio of 30:6; the stirring reaction process parameters under isothermal conditions are: a closed magnetic stirring reaction at 85 degrees Celsius for 8 hours. By adopting the above technical solution, N,N-dimethylformamide in the mixed solvent system provides basic solubility, and toluene, as an azeotropic dehydrating agent, provides a physicochemical basis for subsequent removal of condensation water. An isothermal reaction at 85 degrees Celsius for 8 hours is sufficient to allow the epoxy groups and amine groups to undergo relatively complete ring-opening addition, generating sufficient side-chain hydroxyl groups for consumption in subsequent condensation reactions.

[0018] Preferably, in step S2, the 1,4-phenylenediboric acid is completely dissolved in 10 parts by volume of N,N-dimethylformamide to form a pre-solution, which is then added dropwise to the skeleton prepolymer solution in batches. The process parameters for the dehydration reaction are: heating to 115 degrees Celsius to bring the reaction system to a slight boiling reflux state, continuously discharging the azeotrope of water and toluene generated by the reaction using a water separator, and refluxing for 3 hours. By adopting the above technical solution, the pre-dissolution of powder and the batch dropwise addition operation prevent the local crosslinking rate of the system from being too fast, which would cause polymer agglomeration. Utilizing the azeotropic properties of toluene and water, the water generated by the esterification reaction is continuously separated at a slight boiling state of 115 degrees Celsius. This operation forces the reaction to dehydrate and close the ring, improving the conversion rate of dynamic covalent bonds.

[0019] Preferably, in step S3, the alcohol solvent is anhydrous methanol; the dropping and stirring parameters of the complexing solution are as follows: it is slowly added to the reaction system at a flow rate of 1 drop per second under mechanical stirring at 500 rpm, and stirred at a constant temperature of 60 degrees Celsius for 1.5 hours. By adopting the above technical solution, anhydrous methanol has the ability to dissolve metal salts and has a low boiling point, making it easy to remove in the subsequent drying process. Controlling the dropping rate and stirring speed ensures that the transition metal ions are uniformly dispersed and penetrate into the polymer network, avoiding a sudden increase in local metal ion concentration that could lead to large-volume solidification and deadlock.

[0020] Preferably, in step S4, the undesirable solvent is acetone. The specific precipitation operation is as follows: under high-speed shear stirring at 1000 rpm, the viscous resin liquid is dripped into 500 parts by volume of acetone in a thin stream. The vacuum drying adopts a gradient vacuum drying process, drying sequentially at 60°C and -0.1 MPa for 4 hours, followed by drying at 105°C and -0.1 MPa for 12 hours. By adopting the above technical solution, the undesirable solvent characteristics of acetone induce phase separation, causing the resin skeleton to rapidly shrink and precipitate in solid form, forcibly removing the primary solvent encapsulated within the resin. The gradient vacuum drying process initially removes low-boiling-point components at a lower temperature, and then treats the residual high-boiling-point solvent at a higher temperature in the later stage. This stepwise temperature increase prevents solvent boil-off and avoids the formation of internal pore structures in the material.

[0021] Preferably, in step S4, the process parameters for hot-press welding are: hot-pressing and degassing at 100 degrees Celsius and 10 MPa for 20 minutes. By employing this technical solution, the 100-degree Celsius thermal field promotes the dissociation of metal coordination bonds within the polymer, activating borate ester bonds to carry out topological exchange reactions. Combined with the application of 10 MPa external pressure, the macroscopic interface of the powder particles deforms and adheres tightly. Free polymer segments diffuse and fuse across the original particle boundaries, and solidify into a dense, integral structure after pressurized cooling.

[0022] This invention provides a reprocessable epoxy-based glass polymer material and its preparation method. It has the following beneficial effects: 1. This invention utilizes bisphenol F epoxy resin and triethylenetetramine to form a rigid main framework, and introduces anhydrous zinc chloride or anhydrous ferric chloride to construct a secondary physical coordination network. Under room temperature conditions, metal ions coordinate with heteroatoms in the network to form physical locks, effectively suppressing the relative slippage of free chain segments. This results in an elastic modulus exceeding 2.1 GPa and a fracture strength exceeding 65 MPa, overcoming the technical defect of traditional dynamically cross-linked polymer materials where the introduction of remodelability leads to a significant decrease in room temperature mechanical properties.

[0023] 2. This invention introduces suspended segments into the main framework via the monoepoxy group of phenyl glycidyl ether, and constructs a thermally reversible dynamic covalent network in combination with 1,4-phenylenediboric acid. The design of the suspended segments significantly reduces the steric hindrance around the reaction sites. After physical coordination dissociation under hot pressing at 100°C, the borate ester bonds can rapidly undergo topological exchange reactions, promoting deep segment entanglement of the pulverized polymer particles across the macroscopic fragmentation interface, resulting in a material reprocessing mechanical strength recovery rate of over 97%.

[0024] 3. This invention employs a mixed solvent azeotropic dehydration technique during the condensation reaction stage to continuously remove generated water, thereby promoting the forward esterification reaction and ensuring the degree of network crosslinking. Simultaneously, during the polymer precipitation stage, a combination of poor solvent phase separation and gradient vacuum drying completely removes the polar solvent encapsulated within the resin, eliminating the internal plasticizing effect caused by solvent residue and preventing internal porosity and structural loosening of the material due to solvent vaporization during reprocessing. Attached Figure Description

[0025] Figure 1 These are dynamic mechanical and stress relaxation characteristics of Embodiment 1 and Comparative Examples 1-2 of the present invention; Figure 2 These are the room temperature tensile stress-strain response diagrams of Embodiment 1 and typical defect comparative examples 2, 4, and 5 of the present invention; Figure 3 This is a comparison diagram of the tensile stress-strain response of the original specimen of Example 1 of the present invention and the reprocessed specimens of Comparative Examples 1 and 3. Detailed Implementation

[0026] 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.

[0027] Bisphenol F type epoxy resin, CAS number 9003-36-5, industrial grade, epoxy equivalent of 160-180g / eq, its molecular structure contains two terminal epoxy groups.

[0028] Phenylated glycidyl ether, CAS number 122-60-1, analytical grade, molecular formula C9H10O2, its molecular structure contains a benzene ring and a terminal epoxy group.

[0029] Triethylenetetramine, CAS number 112-24-3, industrial grade, with an active hydrogen equivalent of approximately 24 g / eq, contains two primary amine groups and two secondary amine groups in its molecular structure.

[0030] 1,4-Phenylatedorboic acid, CAS number 4612-26-4, analytical grade, molecular formula C6H8B2O4, its molecular structure is a benzene ring with two boric acid groups attached at the para position.

[0031] Anhydrous zinc chloride (CAS No. 7646-85-7), anhydrous ferric chloride (CAS No. 7758-89-6), and copper chloride (CAS No. 7447-39-4) are all commercially available analytical grade products used as coordination agents to provide transition metal ions.

[0032] N,N-dimethylformamide, toluene, acetone, and anhydrous methanol, as well as other common reaction solvents, azeotropic dehydrating agents, or purification and washing solvents, are all commercially available analytical grade or higher products.

[0033] 3K carbon fiber cloth, with a 3K twill weave and a surface density of 200g / m2, is a commercially available standard industrial-grade product.

[0034] Example 1: This invention provides a reprocessable epoxy-based glass polymer material, which comprises the following components in parts by weight: bisphenol F epoxy resin: 8.50 parts; phenyl glycidyl ether: 7.51 parts; triethylenetetramine: 2.44 parts; 1,4-phenylenediboric acid: 4.14 parts; anhydrous zinc chloride: 0.18 parts.

[0035] A method for preparing a reprocessable epoxy-based glass polymer material is also provided, comprising the following steps: S1. Add 8.50 parts of bisphenol F epoxy resin and 7.51 parts of phenyl glycidyl ether to a three-necked flask equipped with a mechanical stirrer, condenser and water separator. Add 30 parts by volume of the main solvent N,N-dimethylformamide and 6 parts by volume of the azeotropic dehydrating agent toluene. Stir mechanically at 300 r / min until the system becomes a transparent and homogeneous solution. Then accurately add 2.44 parts of triethylenetetramine. Place the system in a constant temperature oil bath and react with magnetic stirring at 85°C for 8 hours to allow the epoxy groups and amine groups to undergo a complete ring-opening addition reaction, and obtain a skeletal prepolymer solution containing a large number of side-chain diol structures. S2. 4.14 parts of 1,4-phenylenediboric acid were completely dissolved in 10 parts by volume of N,N-dimethylformamide. To prevent excessive local concentration from causing cross-linking and agglomeration, the solution was slowly added dropwise in 3 to 5 portions to the prepolymer solution. The oil bath was then heated to 115°C to bring the reaction system to a gentle reflux state. A water separator was used to continuously condense and discharge the condensed water and toluene azeotrope generated during the reaction. During the reaction, water droplets were observed to continuously accumulate and be discharged from the bottom of the water separator. The reflux reaction was continued for 3 hours until no new water droplets were generated in the water separator, indicating that the forward condensation of the dynamic covalent network supporting the reprocessable function was completely completed. The solution was then allowed to cool naturally to 60°C. S3. Dissolve 0.18 parts of anhydrous zinc chloride in 5 parts of anhydrous methanol using ultrasonication to form a transparent complex solution. Under vigorous mechanical stirring at 500 r / min, slowly add the solution dropwise to the reaction system at a strict flow rate of 1 drop / second. With the introduction of transition metal ions, the viscosity of the system shows a macroscopic increase. Continue stirring at a constant temperature of 60℃ for 1.5 hours to allow Zn2+ to fully combine with the secondary amine groups and ether oxygen atoms in the network to form metal coordination bonds and obtain a uniform high-viscosity resin solution. S4. Cool the above resin solution to room temperature. Under high-speed shear stirring at 1000 r / min, slowly drip the resin solution into 500 parts by volume of acetone, a poor solvent. The resin skeleton shrinks rapidly and precipitates into solid particles, completely removing the residual solvent. Collect the precipitated solid particles by filtration and wash them twice with fresh acetone. Place the solid particles in a vacuum drying oven. To prevent the solvent from boiling out and causing internal pores in the material, a gradient drying process is used. Dry the particles at 60℃ and -0.1 MPa for 4 hours, then heat to 105℃ and dry at -0.1 MPa for 12 hours. Collect the pure particle powder without solvent residue. Put the powder into a stainless steel mold and place it in a flat vulcanizing machine. Hot press and degas at 100℃ and 10 MPa for 20 minutes. After cooling under pressure to room temperature, demold the material to obtain a reprocessable epoxy-based glass polymer material sample.

[0036] Example 2: The present invention provides a reprocessable epoxy glass polymer material, wherein the polymer material comprises the following components in parts by weight: bisphenol F epoxy resin: 14.17 parts; phenyl glycidyl ether: 2.50 parts; triethylenetetramine: 2.44 parts; 1,4-phenylenediboric acid: 4.14 parts; anhydrous zinc chloride: 0.18 parts.

[0037] A method for preparing a reprocessable epoxy-based glass polymer material is also provided, comprising the following steps: S1. Add 14.17 parts of bisphenol F epoxy resin and 2.50 parts of phenyl glycidyl ether to a three-necked flask equipped with a mechanical stirrer, condenser and water separator. Add 30 parts by volume of N,N-dimethylformamide and 6 parts by volume of toluene. Stir mechanically until the system is homogeneously dissolved. Add 2.44 parts of triethylenetetramine. Place in a constant temperature oil bath and stir magnetically at 85°C for 8 hours to complete the complete ring opening of the epoxy resin and obtain a prepolymer solution with high crosslinking density. S2. Dissolve 4.14 parts of 1,4-phenylenediboric acid in 10 parts by volume of N,N-dimethylformamide, and add it dropwise in batches to the above prepolymer solution. Heat the system to 115°C under slight boiling reflux, and use a water separator to continuously strip the condensed water and toluene azeotrope generated in the reaction. Reflux the dehydration reaction for 3 hours, and then cool it down to 60°C. S3. Dissolve 0.18 parts of anhydrous zinc chloride in 5 parts by volume of anhydrous methanol; slowly add it dropwise to the reaction system under vigorous mechanical stirring, and continue stirring at a constant temperature of 60°C for 1.5 hours to form metal coordination crosslinking, and obtain a high viscosity resin liquid. S4. Cool the resin solution to room temperature and drop it dropwise into 500 parts by volume of acetone under high-speed stirring for phase separation and precipitation. The polymer condenses and precipitates out. Collect the precipitate by filtration and wash it repeatedly with acetone. Place the solid particles in a vacuum device and dry them under gradient vacuum at 60°C and 105°C in sequence to collect the pure particle powder. Put the powder into a mold and hot press it at 100°C and 10MPa for 20 minutes. Hold the pressure, cool, and demold to obtain a reprocessable epoxy glass polymer material.

[0038] Example 3: The present invention provides a reprocessable epoxy glass polymer material, wherein the polymer material comprises the following components in parts by weight: bisphenol F epoxy resin: 2.83 parts; phenyl glycidyl ether: 12.52 parts; triethylenetetramine: 2.44 parts; 1,4-phenylenediboric acid: 4.14 parts; anhydrous zinc chloride: 0.18 parts.

[0039] A method for preparing a reprocessable epoxy-based glass polymer material is also provided, comprising the following steps: S1. Add 2.83 parts of bisphenol F epoxy resin and 12.52 parts of phenyl glycidyl ether to a three-necked flask, add 30 parts by volume of N,N-dimethylformamide and 6 parts by volume of toluene mixed solvent, and stir to dissolve; add 2.44 parts of triethylenetetramine, and react magnetically at 85°C for 8 hours. Due to the high proportion of monoepoxy groups, a prepolymer solution containing a large number of free suspended chain segments is formed in this stage. S2. Dissolve 4.14 parts of 1,4-phenylenediboric acid in 10 parts by volume of N,N-dimethylformamide, and slowly add it dropwise to the prepolymer solution; heat to 115°C and reflux for 3 hours to dehydrate, use a water separator to completely break the esterification reaction equilibrium, and then cool to 60°C for later use. S3. Dissolve 0.18 parts of anhydrous zinc chloride in 5 parts of anhydrous methanol; slowly add it dropwise to the reaction system through a dropping funnel, and continue stirring at a constant temperature of 60°C for 1.5 hours to anchor and lock the highly free suspended chain segments using metal coordination bonds. S4. The liquid resin of the system is dropped into 500 parts by volume of acetone and stirred vigorously to initiate phase separation and precipitation. The product is filtered and washed. The washed product is dried under vacuum at a gradient from 60℃ to 105℃ and collected as pure particles. The particles are placed in a mold and hot-pressed at 100℃ and 10MPa for 20 minutes. After cooling and demolding, a reprocessable epoxy glass polymer material is obtained.

[0040] Example 4: The present invention provides a reprocessable epoxy glass polymer material, wherein the polymer material comprises the following components in parts by weight: bisphenol F epoxy resin: 8.50 parts; phenyl glycidyl ether: 7.51 parts; triethylenetetramine: 2.44 parts; 1,4-phenylenediboric acid: 4.14 parts; anhydrous zinc chloride: 0.01 parts.

[0041] A method for preparing a reprocessable epoxy-based glass polymer material is also provided, comprising the following steps: S1. Dissolve 8.50 parts of bisphenol F epoxy resin and 7.51 parts of phenyl glycidyl ether completely in a mixed solvent of 30 parts by volume of N,N-dimethylformamide and 6 parts by volume of toluene; add 2.44 parts of triethylenetetramine, and stir under closed conditions at 85°C for 8 hours to achieve skeleton prepolymerization. S2. Add dropwise a solution pre-dissolved with 4.14 parts of 1,4-phenyldiboronic acid; heat the system to 115°C and reflux to dehydrate for 3 hours, remove azeotropic water through a water separator to solidify the covalent network, and allow it to cool naturally to 60°C. S3. Dissolve 0.01 parts of anhydrous zinc chloride in 5 parts by volume of anhydrous methanol; add dropwise to the reaction system, and continue stirring at a constant temperature of 60°C for 1.5 hours to construct a mild physical coordination network; S4. The resin liquid is dropped into 500 parts by volume of acetone for phase separation and precipitation. After filtration and washing, it is subjected to gradient vacuum drying to remove impurities. The resulting dry powder is loaded into a mold and hot-pressed at 100℃ and 10MPa for 20 minutes. After cooling and demolding, a reprocessable epoxy glass polymer material is obtained.

[0042] Example 5: The present invention provides a reprocessable epoxy glass polymer material, the polymer material comprising the following components in parts by weight: bisphenol F epoxy resin: 8.50 parts; phenyl glycidyl ether: 7.51 parts; triethylenetetramine: 2.44 parts; 1,4-phenylenediboric acid: 4.14 parts; anhydrous zinc chloride: 0.45 parts.

[0043] A method for preparing a reprocessable epoxy-based glass polymer material is also provided, comprising the following steps: S1. Dissolve 8.50 parts of bisphenol F epoxy resin and 7.51 parts of phenyl glycidyl ether in a mixed solvent of 30 parts by volume of N,N-dimethylformamide and 6 parts by volume of toluene; add 2.44 parts of triethylenetetramine, and stir continuously for 8 hours in an oil bath at 85°C to form the initial network. S2. Add 4.14 parts of pre-dissolved 1,4-phenylenediboric acid dropwise in batches; then heat to 115°C and reflux for 3 hours to completely remove the water molecules of the condensation byproduct, and cool to 60°C. S3. Dissolve 0.45 parts of anhydrous zinc chloride in 5 parts of anhydrous methanol using ultrasonication. To prevent instantaneous local deadlock caused by high concentrations of metal salt, add the solution slowly to the system at a rate of less than 1 drop / second, and continue stirring at a constant temperature of 60°C for 1.5 hours to obtain a highly coordinated and locked viscous resin. S4. The resin liquid is dropped into 500 parts by volume of acetone, a poor solvent, to complete phase separation and precipitation. The product is then filtered and washed with fresh acetone. After the powder product is thoroughly dried under gradient vacuum to remove the solvent, it is molded and hot-pressed at 100℃ and 10MPa for 20 minutes. After cooling to room temperature, it is demolded to obtain a reprocessable epoxy glass polymer material.

[0044] Example 6: The present invention provides a reprocessable epoxy glass polymer material, the polymer material comprising the following components in parts by weight: bisphenol F type epoxy resin: 8.50 parts; phenyl glycidyl ether: 7.51 parts; triethylenetetramine: 2.44 parts; 1,4-phenylenediboric acid: 4.14 parts; anhydrous ferric chloride: 0.22 parts.

[0045] A method for preparing a reprocessable epoxy-based glass polymer material is also provided, comprising the following steps: S1. Dissolve 8.50 parts of bisphenol F epoxy resin and 7.51 parts of phenyl glycidyl ether in 30 parts by volume of N,N-dimethylformamide and 6 parts by volume of toluene; add 2.44 parts of triethylenetetramine, and stir at 85°C for 8 hours to prepare a framework prepolymer. S2. Add a pre-solution containing 4.14 parts of 1,4-phenylenediboric acid; heat to 115°C and dehydrate by reflux using a water separator for 3 hours to fully form the dynamic covalent network, then cool to 60°C. S3. Dissolve 0.22 parts of anhydrous ferric chloride in 5 parts of anhydrous methanol; slowly add it dropwise to the reaction system. The system will show a significant color deepening as iron ions are introduced. Continue stirring at a constant temperature of 60°C for 1.5 hours to form an iron-nitrogen / iron-oxygen coordination cross-linking network. S4. The obtained homogeneous liquid phase is dropped into 500 parts by volume of acetone to separate and precipitate the solid component. After filtration and washing, the solid component is placed in a vacuum device for gradient drying. The powder is collected and molded. It is then hot-pressed at 100℃ and 10MPa for 20 minutes. After complete cooling, the solid component is demolded to obtain a reprocessable epoxy glass polymer material.

[0046] Comparative Example 1: Compared with Example 1, the difference is that monofunctional phenyl glycidyl ether (PGE) is not added to the formulation, and its missing molar amount is replaced with bisphenol F epoxy resin of equal epoxy equivalent, that is, the bisphenol F epoxy resin is adjusted to 17.00 parts and phenyl glycidyl ether is not added, and the remaining steps are the same.

[0047] Comparative Example 2: The difference from Example 1 is that anhydrous zinc chloride is not added, but the other steps are the same.

[0048] Comparative Example 3: Compared with Example 1, the difference is that the amount of anhydrous zinc chloride added is increased to 1.50 parts, while the rest of the steps are the same.

[0049] Comparative Example 4: Compared with Example 1, the difference is that toluene is not added in steps S1 and S2, and a water separator is not used. The reaction is directly heated and refluxed in a closed system. The remaining steps are the same.

[0050] Comparative Example 5: Compared with Example 1, the difference is that the acetone phase separation and precipitation operation in step S4 is not performed. Instead, the viscous resin liquid obtained in step S3 is placed in a vacuum drying oven and the DMF solvent is removed by vacuuming at 120°C for a long time. The remaining steps are the same.

[0051] Test Example 1: 1. The polymer dry powder materials prepared in Example 1, Comparative Example 1, and Comparative Example 2 were placed in a standard rectangular mold of a flat vulcanizing machine and hot-pressed at 100°C and 10MPa. After cooling and demolding, the materials were cut into rectangular strips with dimensions of approximately 30.5mm × 5.2mm × 2.1mm using a mechanical cutter, and the edges of the strips were lightly sanded with fine sandpaper to eliminate stress concentration defects.

[0052] 2. The temperature variation test of the specimen was performed using a dynamic thermomechanical analyzer in single cantilever beam mode. The oscillation frequency of the instrument was set to 1.0 Hz, and the dynamic strain amplitude was controlled at 0.1% to ensure that the test was conducted within the linear viscoelastic region of the material.

[0053] The test temperature range was set from 25℃ to 150℃, and the heating rate was maintained at 3.0℃ / min. The changes in energy storage modulus and loss factor with temperature were continuously recorded, and the peak temperature of the loss factor curve was extracted as the glass transition temperature of the system.

[0054] 3. Clamp specimens of the same specifications in the test fixture and perform isothermal stress relaxation tests. Control the ambient temperature to rise rapidly to the target test temperature, set at 85℃, 95℃, 100℃, and 110℃ respectively, and hold at this temperature for 5 minutes to eliminate the thermal history inside the material.

[0055] Subsequently, a constant step tensile strain of 1.0% was instantaneously applied to the spline, and the instrument automatically recorded continuous data on the decay of the nominal stress inside the material over time. The time point corresponding to the stress value decaying to 36.8% of the initial maximum stress value was extracted and recorded as the characteristic relaxation time.

[0056] 4. Organize the characteristic relaxation time data at different test temperatures, and plot the natural logarithm of the characteristic relaxation time against the reciprocal of the test thermodynamic temperature.

[0057] By performing linear regression fitting on discrete data points, the apparent activation energy of topological exchange reactions in each cross-linked network system is calculated based on the Arrhenius equation.

[0058] Table 1. Test results of dynamic mechanical and thermodynamic parameters of Example 1 and each comparative example.

[0059] Based on the data in Table 1 and Figure 1 At room temperature of 25°C, the initial storage modulus of Example 1 reached 2.42 GPa, exhibiting the rigidity characteristics of typical engineering plastics, while the modulus of Comparative Example 2, which lacked the zinc chloride component, was only 0.84 GPa, and the glass transition temperature also dropped significantly to 52.1°C.

[0060] Actual laboratory observations have confirmed that the introduction of these trace transition metal ions forms dense physical anchor points within the polymer backbone. The coordination bonds formed by the lone pairs of electrons of nitrogen / oxygen atoms and zinc ions are in a dormant and locked state at room temperature, which greatly restricts the relative slippage of polymer chain segments, thereby compensating for the loss of room temperature strength caused by the introduction of monoepoxy monomers.

[0061] When the ambient temperature rises to the high-elasticity range of 100℃, this physical coordination crosslinking undergoes thermal dissociation, and the network topological exchange behavior of the material begins to be dominated by the internal dynamic covalent bonds of the borate ester. Experimental results of stress relaxation clearly show that Comparative Example 1 without added phenyl glycidyl ether exhibits a characteristic relaxation time of 4853.7 seconds at this temperature, and the calculated activation energy is as high as 92.4 kJ / mol. The dynamic covalent bonds are forcibly embedded in the rigid backbone formed by the bisphenol F skeleton, and there is a very strong steric hindrance effect around the reaction sites, making it difficult for the macromolecular chain segments to undergo effective conformational inversion to complete the transesterification reaction.

[0062] Example 1 utilizes phenyl glycidyl ether to construct unilaterally free suspended segments, pushing the previously confined reaction sites into porous regions with greater spatial freedom. This drastically reduces the stress dissipation time at the same temperature to 25.3 seconds and lowers the activation energy to 47.8 kJ / mol. At the macroscopic level, the material not only maintains the mechanical load-bearing capacity required for practical applications, but its internal structure can also rapidly initiate rheological and network rearrangement under thermal stimulation, completely eliminating the technical pain point of traditional dynamic cross-linked networks that require ultra-high temperatures or extended reaction times for reprocessing.

[0063] Test Example 2: 1. The polymer materials prepared in Example 1 and Comparative Examples 1 to 5 were placed in the mold of a flat vulcanizing machine and hot-pressed into a sheet with a thickness of 2.0 mm at 100°C and 10 MPa. After cooling and demolding, the sheet was cut into 1BA dumbbell-shaped tensile test specimens conforming to ISO 527-2 standard using a pneumatic cutter. The edges of the parallel sections of the specimens were ground to remove minor cracks and burrs generated during the cutting process.

[0064] 2. Place all processed test specimens in a constant temperature and humidity chamber, setting the ambient temperature to 25℃ and the relative humidity to 50%. Perform 24-hour conditioning under this standard environment to promote thermodynamic equilibrium of the polymer chains within the material and eliminate residual internal stress introduced by hot pressing.

[0065] 3. A universal testing machine was used to conduct room temperature tensile failure tests on each group of specimens after condition adjustment. The two ends of the specimens were fixed in the upper and lower pneumatic clamps of the testing machine, with the initial displacement between the clamps calibrated to 30 mm. An axial tensile load was applied to the specimens at a constant rate of 5 mm / min, and the instrument simultaneously recorded continuous data from the load cell and displacement cell until the sample underwent macroscopic fracture.

[0066] 4. Collect and properly preserve the waste samples after fracture of each group of specimens, and use sealed bags for classification and labeling for subsequent hot-pressing remodeling experiments. Extract the characteristic points of the stress-strain curves generated by the testing machine, calculate the elastic modulus, yield strength, fracture strength, and elongation at break of each group of formulations, test 5 parallel samples for each group, and take the arithmetic mean.

[0067] Table 2. Results of room temperature tensile mechanical properties test of Example 1 and each comparative example.

[0068] Based on the data in Table 2 and Figure 2 Example 1 exhibits an elastic modulus exceeding 2.1 GPa and a fracture strength of 65.7 MPa at room temperature, providing a reliable load-bearing foundation. Comparative Examples 1 and 3, due to their stronger skeleton rigidity or extremely high crosslinking density, have room temperature mechanical parameters that are on the same order of magnitude as or even slightly higher than those of Example 1. This is consistent with the basic laws of polymer physics, and the true defects in their network topology will be exposed during subsequent hot-pressing reshaping.

[0069] The loss of basic polymer strength often stems from deficiencies in the reaction process or microscopic interactions. Observation of the data in Comparative Example 2 reveals that the elastic modulus drops sharply to 842.1 MPa after the zinc chloride component is stripped. The freely moving suspended chain segments at room temperature are highly susceptible to irreversible slippage in the absence of metal ion coordination anchorage, confirming the decisive role of the physical coordination network in solidifying the main chain conformation and compensating for the strength loss caused by the introduction of monofunctional monomers.

[0070] The thermodynamic equilibrium disruption mechanism during polymerization also has a profound impact on the mechanical properties of the final material. In Comparative Example 4, due to the absence of an azeotropic dehydration process, the condensation water accumulated in the reaction system forced the borosilicate esterification reaction to approach the dead zone of Le Chatelier equilibrium. The large number of unreacted end groups resulted in extremely low crosslinking density of the polymer network and difficulty in increasing the molecular weight, macroscopically exhibiting an extremely weak fracture strength of less than 10 MPa. The material even showed a slight tendency for viscous flow at room temperature.

[0071] Comparative Example 5 reveals the hidden risks in the post-processing stage. Polar solvent molecules that failed to be removed by phase separation interspersed between polymer segments, severing secondary interactions and causing an abnormally high pseudo-elongation at break of 158.3%. Although this internal plasticizing effect gives the material a false impression of flexibility in the short term, it masks the true structural mechanical characteristics of the cross-linked network and is highly susceptible to severe dimensional instability and embrittlement failure due to solvent evaporation during long-term thermodynamic cycling.

[0072] Test Example 3: 1. The waste samples from Examples 1, 1, 3, and 4, which were classified and retained after tensile fracture in Test Example 2, were collected and placed in a micro-mechanical pulverizer for low-temperature pulverization. The debris was sieved through a standard test sieve with a particle size between 1.0 mm and 2.0 mm to collect macroscopic polymer particles as the base material for this test.

[0073] 2. Accurately weigh equal amounts of the above four groups of polymer particles, and evenly spread them into the cavity of a standard dumbbell-shaped stainless steel mold that has been pre-coated with a release agent. Use a glass rod to smooth the surface of the particles to ensure that there are no obvious gaps or thickness differences inside the mold.

[0074] 3. Move the filled mold between the upper and lower heating plates of the flat vulcanizing machine and set the temperature to rise to 100℃ simultaneously. Under constant temperature conditions, slowly apply a closing pressure of 10MPa to the mold through the hydraulic system and maintain the pressure at this parameter for 20 minutes to drive the thermal diffusion of polymer chain segments and dynamic network recombination at the interface between the crushed particles.

[0075] 4. After the pressure holding period, disconnect the heating power supply and turn on the water cooling circulation system to cool the mold to 25°C while maintaining pressure. Unload the hydraulic pressure to open the mold cavity, observe and record the macroscopic forming state of each group of materials, and take out the reshaped sample to measure the specific dimensions.

[0076] 5. Clamp the reshaped specimen with intact appearance and structure in a universal testing machine, and perform a second tensile fracture test at a tensile rate of 5 mm / min under a standard environment of 25℃. Record the tensile fracture strength after reprocessing. Combined with the original fracture strength data of each formulation measured in Table 2, calculate the specific percentage recovery of mechanical strength.

[0077] Table 3. Test results of mechanical properties and recovery rate of hot pressing reprocessing in Example 1 and various comparative examples.

[0078] Based on the data in Table 3 and Figure 3 In Example 1, after thorough particle crushing and hot-pressing at 100°C, the fracture strength remained as high as 64.1 MPa, and its strength recovery rate of 97.6% confirmed that the cross-linked network possesses excellent topological reconstruction efficiency. The suspended chain segments floating freely in the network pores at the microscopic level provide an extremely low steric hindrance environment for the thermodynamic dissociation and recombination of borate ester bonds, enabling polymer chain segments to achieve deep entanglement across the macroscopic fracture interface in a short time.

[0079] Systems relying on the rigidity of the main chain to bear loads exhibit severe limitations during the thermal processing stage. In Comparative Example 1, which did not incorporate the design of suspended chain segments, the interior of the secondary spline was filled with micropores, and the fracture strength dropped to 16.7% of the original state. The dynamic covalent bonds tightly embedded in the rigid framework of bisphenol F could not complete conformational inversions at a sufficient frequency under the thermal energy provided at 100°C, and only very shallow molecular diffusion and physical adhesion occurred at the particle interface.

[0080] Even a slight deviation in the material composition ratio can paralyze the entire dynamic mechanism.

[0081] Although Comparative Example 3 maintained a similar high strength to Example 1 at room temperature, the excessive zinc ions constructed dense and difficult-to-dissociate secondary coordination nodes within the system. These physical anchors failed to undergo effective thermal melting at 100°C, acting like latches to firmly clamp the suspended side chains, completely blocking the rheological path of the entire macromolecular network in space, causing the waste material to disintegrate into powder the instant the external mold pressure was removed.

[0082] Defects in the polymerization process are further amplified in the reshaping stage. In Comparative Example 4, due to incomplete removal of moisture from the reaction system, the network structure was already incomplete. During the secondary heating and pressurization process, the remaining moisture vaporized, forming numerous microscopic bubble cavities within the material, causing its already weak macroscopic mechanical structure to completely lose its load-bearing capacity. Finding a precise thermodynamic equilibrium between the local degree of freedom decoupling in the polymer topological space and external physical cross-linking anchoring, coupled with a thoroughly pure polymerization separation process, is the only way to bridge the mutually exclusive gap between the high rigidity at room temperature and the rapid repair at low temperature of traditional dynamic resins.

[0083] 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 reprocessable epoxy-based glass polymer material, characterized in that, The polymer material is made from raw materials comprising the following parts by weight: Bisphenol F type epoxy resin: 2.83–14.17 parts; Phenylated glycidyl ether: 2.50–12.52 parts; Triethylenetetramine: 2.44 parts; 1,4-Phenylated boric acid: 4.14 parts; Metal salts: 0.01–0.45 parts; The bisphenol F epoxy resin undergoes a ring-opening addition reaction with triethylenetetramine to crosslink and form a rigid main framework. The monoepoxy group of the phenyl glycidyl ether introduces a suspended chain segment into the main skeleton to reduce the steric hindrance around the reaction site. The 1,4-phenylenediboronic acid undergoes condensation with the diol structure generated by the main backbone side chain to construct a thermally reversible dynamic covalent network. The metal ions in the metal salt coordinate with the heteroatoms in the network to form a physical locking network that inhibits the relative slippage of free chain segments at room temperature.

2. The reprocessable epoxy glass polymer material according to claim 1, characterized in that, The metal salt is anhydrous zinc chloride or anhydrous ferric chloride.

3. The reprocessable epoxy glass polymer material according to claim 1, characterized in that, The polymer material after molding has a room temperature elastic modulus greater than 2.1 GPa and a fracture strength greater than 65 MPa when tested at room temperature (25°C).

4. A reprocessable epoxy-based glass polymer material and its preparation method, characterized in that, The method for preparing any one of the reprocessable epoxy-based glass polymer materials described in 1-3 is characterized by comprising the following steps: S1. Bisphenol F epoxy resin and phenyl glycidyl ether are added to a mixed solvent and stirred to dissolve; then triethylenetetramine is added and stirred under constant temperature to obtain a skeleton prepolymer solution. S2. Dissolve 1,4-phenylenediboric acid in a solvent and slowly add it dropwise to the above-mentioned skeleton prepolymer solution; heat the system to bring it to a reflux state and continuously remove the condensed water generated in the reaction to carry out the dehydration reaction, and then cool it down; S3. Dissolve the metal salt in an alcohol solvent to form a complexation solution; add the complexation solution dropwise to the reaction system under stirring, and stir at a constant temperature to form metal coordination crosslinking, thereby obtaining a viscous resin solution; S4. The above viscous resin liquid is dropped into a poor solvent for phase separation and precipitation. The precipitated solid particles are collected, washed and vacuum dried, loaded into a mold for hot pressing, and cooled and demolded to obtain the reprocessable epoxy glass polymer material.

5. The reprocessable epoxy glass polymer material and its preparation method according to claim 4, characterized in that, In step S1, the mixed solvent is composed of N,N-dimethylformamide and toluene in a volume ratio of 30:6; the stirring reaction process parameters under constant temperature conditions are: a closed magnetic stirring reaction at 85°C for 8 hours.

6. The reprocessable epoxy-based glass polymer material and its preparation method according to claim 4, characterized in that, In step S2, the 1,4-phenylenediboric acid is completely dissolved in 10 parts by volume of N,N-dimethylformamide to form a pre-solution, which is then added dropwise to the skeleton prepolymer solution in batches. The process parameters for the dehydration reaction are as follows: the temperature is raised to 115°C to bring the reaction system into a slight boiling reflux state, and the azeotrope of water and toluene generated by the reaction is continuously discharged using a water separator, and the reflux reaction is carried out for 3 hours.

7. The reprocessable epoxy-based glass polymer material and its preparation method according to claim 4, characterized in that, In step S3, the alcohol solvent is anhydrous methanol; the dropping and stirring parameters of the complexing solution are as follows: it is slowly added to the reaction system at a flow rate of 1 drop / second under mechanical stirring at 500 r / min, and stirred at a constant temperature of 60°C for 1.5 hours.

8. The reprocessable epoxy glass polymer material and its preparation method according to claim 4, characterized in that, In step S4, the undesirable solvent is acetone. The specific precipitation operation is as follows: under high-speed shear stirring at 1000 r / min, the viscous resin liquid is dripped into 500 parts by volume of acetone in a thin stream.

9. The reprocessable epoxy glass polymer material and its preparation method according to claim 4, characterized in that, In step S4, the vacuum drying adopts a gradient vacuum drying process, drying at 60℃ and -0.1MPa for 4 hours in sequence, and then heating to 105℃ and drying at -0.1MPa for 12 hours.

10. The reprocessable epoxy glass polymer material and its preparation method according to claim 4, characterized in that, In step S4, the process parameters for hot pressing are: hot pressing and degassing at 100℃ and 10MPa for 20 minutes.

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