Molecular dynamics simulation method for constructing vitrification-like epoxy resin dynamic crosslinking model

Abstract

The invention relates to a molecular dynamics simulation method for constructing a vitrification-like epoxy resin dynamic crosslinking model, and belongs to the technical field of vitrification-like epoxy resin simulation. Epoxy resin and a cross-linking agent are subjected to a dynamic bond exchange reaction to construct a dynamic cross-linking model, and a molecular dynamics simulation test is adopted to replace a traditional experimental process, so that the defect that an experiment captures molecular movement on a microscale is overcome. According to the method, the crosslinking degree of chemical crosslinking and the reaction times of dynamic crosslinking can be flexibly controlled through molecular dynamics simulation, so that the microscopic mechanism and the thermodynamic property of the glass-like epoxy resin can be deeply researched, and a research framework is provided for optimizing the microstructure and the self-repairing property of the glass-like epoxy resin.

Description

Technical Field

[0001] This patent relates to the field of glass-like epoxy resin simulation technology, and in particular to a molecular dynamics simulation method for constructing a dynamic cross-linking model of glass-like epoxy resin, and a model of dynamic cross-linking of glass-like epoxy resin obtained by this method. Background Art

[0002] Epoxy resin is a thermosetting polymer material widely used in coatings, adhesives, construction, and fiber-reinforced composites due to its excellent mechanical and thermal properties, stability, fatigue resistance, and chemical resistance. However, thermosetting polymers suffer from insolubility and lack of recyclability, making them difficult to recycle. Glass-like epoxy resin is a dynamic covalent network polymer that combines the high crosslinking degree of thermosetting materials with the reshapeability of thermoplastic materials. Through dynamic covalent bonds, the network topology can be reversibly restructured, giving the material advantages such as repairability, recyclability, and processability. This material is an excellent alternative to traditional thermosetting materials. Although a large number of experimental studies have focused on optimizing the macroscopic properties of glass-like epoxy resins, their microscopic dynamic bond exchange mechanism, network reconstruction dynamics, and performance regulation laws still lack a systematic explanation.

[0003] Molecular dynamics simulation, based on classical mechanics, tracks the motion of molecules or atoms within a system through numerical integration, enabling the investigation of the system's microscopic mechanisms and thermodynamic properties. Molecular dynamics simulations are a key research method in the materials field. They can easily construct dynamic crosslinking models of glass-like epoxy resins, which is crucial for understanding the microscopic mechanisms and optimizing the design of self-healing, recyclability, and processability of glass-like epoxy resins. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a molecular dynamics simulation method for constructing a dynamic cross-linking model of a glass-like epoxy resin, so as to conduct in-depth research on the microscopic mechanism and thermodynamic properties of the glass-like epoxy resin and provide a research framework for optimizing the microstructure and self-healing properties of the glass-like epoxy resin.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A molecular dynamics simulation method for constructing a dynamic crosslinking model of a glass-like epoxy resin, the method comprising the following steps:

[0007] S1: Construct an epoxy resin and crosslinker model. According to the ratio of the reaction atoms of epoxy resin and crosslinker, randomly fill the epoxy resin and crosslinker into the simulation box to construct the initial microstructure model of the epoxy resin crosslinking system.

[0008] S2: Template files and mapping files for constructing chemical crosslinking and dynamic crosslinking of epoxy resin and crosslinker.

[0009] S3: setting initial parameters of the initial microstructure model, wherein the initial parameters include the spatial dimension of the microstructure model, the system unit of the microstructure model, the boundary conditions of the microstructure model, and the potential function between atoms in the microstructure model.

[0010] S4: After ensuring the stability of the initial conditions of the simulation, relaxation operations are performed under a canonical ensemble of equal particle number, equal volume, and equal temperature; then relaxation operations are performed under a canonical ensemble of equal particle number, equal pressure, and equal temperature.

[0011] S5: Read the chemical cross-linking template file and mapping file established in S2, perform chemical cross-linking simulation under the microcanonical ensemble with equal particle number, equal volume, and equal energy and the Langevin heat bath temperature control method, and output a chemical cross-linking model in which the epoxy resin and the cross-linking agent have a certain degree of cross-linking.

[0012] S6: The simulation system is subjected to an annealing process under a canonical ensemble of equal particle number, equal pressure, and equal temperature. This process is used to eliminate the internal stress of the highly cross-linked chemically cross-linked model and further stabilize the cross-linked model structure.

[0013] S7: Read the model file of the annealing process completed in S6. After ensuring the stability of the initial conditions of the simulation, read the dynamic cross-linking template file and mapping file established in S2, perform dynamic cross-linking simulation under the microcanonical ensemble of equal particle number, equal volume, and equal energy and the Langevin heat bath temperature control method, and output a dynamic cross-linking model of a glassy epoxy resin.

[0014] Compared with the existing technology, the present application has the following advantages: through molecular dynamics simulation, a dynamic cross-linking model of glass-like epoxy resin is quickly established to simulate the dynamic bond exchange behavior of glass-like epoxy resin. The simulation process is flexible and controllable, and the cross-linking degree of chemical cross-linking and the number of dynamic cross-linking reactions can be flexibly controlled, thereby enabling in-depth research on the microscopic mechanism and thermodynamic properties of glass-like epoxy resin, and providing a research framework for optimizing the microstructure and self-healing properties of glass-like epoxy resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the process of the present invention;

[0016] Figure 2 Use flow charts for fixbond / react directives;

[0017] Figure 3 Schematic diagram of the initial microstructure model for constructing cross-links;

[0018] Figure 4 Schematic diagram of chemical cross-linking;

[0019] Figure 5 Schematic diagram of dynamic cross-linking;

[0020] Figure 6 Schematic diagram of the dynamic bond exchange model. DETAILED DESCRIPTION

[0021] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] See also Figure 1 As shown, the embodiment of the present application discloses a molecular dynamics simulation method for constructing a dynamic crosslinking model of a glass-like epoxy resin, comprising:

[0023] S1: Based on the molecular structure formulas of the epoxy resin and crosslinker, the microstructure models of the epoxy resin and crosslinker were constructed using Materials Studio software. Then, based on the ratio of reactive atoms on the epoxy resin and crosslinker that participate in the chemical crosslinking reaction, the Amorphous Cell module was used to fill the simulation box with epoxy resin to construct an initial crosslinking model. After the construction was completed, the initial model was exported as a data file for subsequent simulation calculations.

[0024] S2: Use Materials Studio software to output the data files of the templates before and after the chemical cross-linking and dynamic cross-linking reactions, and create template files and mapping files based on the schematic diagrams of the chemical cross-linking and dynamic cross-linking reactions.

[0025] S3: Use the Large-scale Atomic Molecular Massively Parallel Simulator (LAMMPS) software to read the data file created in S1 and set the initial parameters of the initial microstructure model; the initial parameters include the random distribution of velocities for all particles, the spatial dimensions of the microstructure model, the system units of the microstructure model, the boundary conditions of the microstructure model, and the potential function between atoms in the microstructure model. Among them, the potential function between atoms in the microstructure model uses a consistent valence force field. This potential function is suitable for organic small molecules and polymers. The calculated system structure and structural energy are relatively accurate and consist of multiple parts, including bond length potential energy, bond angle potential energy, torsional potential energy, out-of-plane bending energy, and non-bonded interactions. Its expression is: E total =E bond +E angle +E torsion +E out-of-plane +E non-bonded

[0026] Where E bond is the bond length potential energy, Eangle is the bond angle potential energy, E torsion is the torsional potential energy, E out-of-plane is the out-of-plane bending energy, E non-bonded It is a non-bonded interaction.

[0027] The bond length potential energy E bond The expression is: E bond =∑k b (r-r0) 2

[0028] Where k b is the bond force constant, r is the actual bond length, and r0 is the equilibrium bond length.

[0029] The bond angle potential energy E angle The expression is:

[0030] Where k θ is the bond angle force constant, θ is the actual bond angle, and θ0 is the equilibrium bond angle;

[0031] The torsional potential energy E torsion The expression is:

[0032] In the formula is the barrier height, n is the number of periods, is the actual dihedral angle, δ is the phase angle (usually 0° or 180°);

[0033] The out-of-plane bending energy E out-of-plane The expression is:

[0034] Where k χ is the out-of-plane bending force constant, n is the number of periods, χ is the actual deviation from the plane, and χ0 is the equilibrium deviation from the plane;

[0035] The non-bonded interactions include LJ potential (Lennard-Jones 12-6 potential) and electrostatic interaction (Coulomb potential). The expression of LJ potential is:

[0036] In the formula ij is the depth of the potential energy well, σ ij is the distance between atom i and atom j when the potential energy of their interaction is exactly zero, r is the interatomic distance, r c is the cutoff radius;

[0037] The expression of the electrostatic effect is:

[0038] Where ε0 is the dielectric constant of vacuum, ε r is the relative dielectric constant of the medium, q i and q j are the charges of atom i and atom j, r is the interatomic distance, r c is the cutoff radius.

[0039] S4: To ensure the stability of the initial simulation conditions, the system is subjected to energy minimization to initialize atomic velocities and eliminate unreasonable stresses in the initial structure. The system is then relaxed in the canonical ensemble (NVT) at 600 K and 298 K, followed by relaxation in the canonical ensemble (NPT) at 298 K and 1 atm, to manipulate the density to a relatively dense state. Relaxation in the canonical ensemble of equal population, equal volume, and equal temperature balances the temperature, eliminates initial structural defects, and provides a stable kinetic energy distribution for the system. Relaxation in the canonical ensemble of equal population, equal pressure, and equal temperature allows the system to adjust its volume while maintaining temperature stability, thereby manipulating the system's density. Relaxation outputs the system's pressure, temperature, and density every 100 steps.

[0040] S5: Read the cross-linking reaction template file and mapping file established in S2, and perform chemical cross-linking simulation under the conditions of equal particle number, equal volume, equal energy microcanonical ensemble (NVE) and Langevin thermal bath thermostat. The chemical cross-linking uses the fixbond / react command (a command for simulating chemical bond exchange, which changes the bond connection relationship between atoms under the conditions of geometry / energy by defining the reaction template). The operation process is as follows: Figure 2 By modifying the parameters of the fix bond / react command (as shown), the number of reactions of reactive atoms is controlled to achieve a specific degree of crosslinking in the system. A data file of the chemical crosslinking results is then output. The atomic coordinates are output every 100 steps during the chemical crosslinking process. The atomic position information obtained from molecular dynamics simulations is then displayed in full dynamic form using OVITO software.

[0041] S6: Read the chemical crosslinking data file, minimize the system's energy, and then relax under the microcanonical ensemble and Langevin thermostat to further stabilize the structure. Then, perform an annealing process under the canonical ensemble with equal particle number, equal pressure, and equal temperature. First, maintain the temperature at room temperature (298K) for a period of time, then gradually increase the temperature from room temperature to a high temperature (298K-800K), maintain it at high temperature for a period of time, and then gradually cool it back to room temperature (800K-298K) to further stabilize the chemically crosslinked structure. During the simulated cooling process, the initial structure of the dynamic crosslinking simulation is formed. The system is briefly equilibrated at room temperature to ensure structural stability. The pressure, temperature, and density of the system are output every 100 steps during the relaxation and annealing processes.

[0042] S7: Perform energy minimization on the structure obtained in S6, read the dynamic cross-linking reaction template file and mapping file established in S2, and then perform dynamic cross-linking simulation under the conditions of equal particle number, equal volume, equal energy and Langevin thermal bath thermostat. The dynamic cross-linking uses the fix bond / react command, and the frequency of command execution is set to limit the number of dynamic cross-linking events. The dynamic cross-linking process outputs the coordinate position of each atom once every 100 steps, and the atomic position information obtained from the molecular dynamics simulation is fully dynamically displayed in the simulation process through the OVITO software.

[0043] The following example uses a molecular dynamics simulation of a disulfide bond dynamic crosslinking model constructed using an epoxy resin (DGEBA) and a crosslinker (AFD). This method specifically describes a molecular dynamics simulation method for a glassy epoxy resin-like dynamic crosslinking model, including:

[0044] S1: Use Materials Studio software to construct microscopic molecular models of DGEBA and AFD, as well as an initial cross-linking model, including:

[0045] Based on the molecular structure of DGEBA and AFD, a microscopic molecular model is drawn and the forces between the atoms under the consistent valence force field are calculated. Then, based on the ratio of reactive atoms participating in the chemical crosslinking reaction on the epoxy resin and the crosslinker (2:1), the Amorphous Cell module is used to fill DGEBA and AFD in a ratio of 60:30 into the simulation box. The number of molecules and the ratio can be set according to actual needs. The side length of the generated box is like Figure 3 Convert the above initial structure into a data file that can be read by LAMMPS for subsequent calculations.

[0046] S2: Schematic diagram of chemical cross-linking and dynamic cross-linking reactions, such as Figure 4 、5 As shown, a template file and a mapping file are established. The template file specifically includes information such as the atomic type, position charge, etc. before and after the reaction, and the mapping file specifically includes the corresponding relationship between the atoms before and after the reaction.

[0047] S3: Use the Large-scale Atomic Molecular Massively Parallel Simulator (LAMMPS) software to read the data file created in S1 and set the initial parameters of the initial microstructure model, including:

[0048] (1) Read the data file of the initial microstructure model;

[0049] (2) Set the unit of the model system to real unit system;

[0050] (3) Set the spatial dimension of the model to 3 dimensions;

[0051] (4) Set the boundaries in the x, y, and z directions to be periodic boundaries;

[0052] (5) Set the cutoff radius to

[0053] (6) Using a consistent valence force field, this potential function is applicable to small organic molecules and polymers. The calculated system structure and structural energy are relatively accurate and consist of multiple parts, including bond length potential energy, bond angle potential energy, torsion potential energy, out-of-plane bending energy, and non-bonded interactions. Its expression is: E total =E bond +E angle +E torsion +E out-of-plane +E non-bonded

[0054] Where E bond is the bond length potential energy, E angle is the bond angle potential energy, E torsion is the torsional potential energy, E out-of-plane is the out-of-plane bending energy, E non-bonded It is a non-bonded interaction.

[0055] The bond length potential energy E bond The expression is: E bond =∑k b (r-r0) 2

[0056] Where k b is the bond force constant, r is the actual bond length, and r0 is the equilibrium bond length.

[0057] The bond angle potential energy Eangle The expression is:

[0058] Where k θ is the bond angle force constant, θ is the actual bond angle, and θ0 is the equilibrium bond angle;

[0059] The torsional potential energy E torsion The expression is:

[0060] In the formula is the barrier height, n is the number of periods, is the actual dihedral angle, δ is the phase angle (usually 0° or 180°);

[0061] The out-of-plane bending energy E out-of-plane The expression is:

[0062] Where k χ is the out-of-plane bending force constant, n is the number of periods, χ is the actual deviation from the plane, and χ0 is the equilibrium deviation from the plane;

[0063] The non-bonded interactions include LJ potential (Lennard-Jones 12-6 potential) and electrostatic interaction (Coulomb potential). The expression of LJ potential is:

[0064] In the formula ij is the depth of the potential energy well, σ ij is the distance between atom i and atom j when the potential energy of their interaction is exactly zero, r is the interatomic distance, r c is the cutoff radius;

[0065] The expression of the electrostatic effect is:

[0066] Where ε0 is the dielectric constant of vacuum, ε r is the relative dielectric constant of the medium, q i and q j are the charges of atom i and atom j, r is the interatomic distance, r c is the cutoff radius.

[0067] S4: Ensure that the initial conditions of the simulation are stable, including:

[0068] Generates a velocity with a Gaussian distribution based on a temperature of 300K;

[0069] Energy minimization;

[0070] Relaxation under a canonical ensemble of equal number of particles, equal volume, and equal temperature, specifically including:

[0071] The step size of the relaxation process is defined as 1 fs;

[0072] The relaxation temperature is defined as 600K;

[0073] Define the relaxation time as 15000 steps, that is, the relaxation time is 15ps;

[0074] The relaxation temperature is defined as 298K;

[0075] Define the relaxation time as 25000 steps, that is, the relaxation time is 25ps;

[0076] Relaxation under a canonical ensemble of equal particle number, equal pressure, and equal temperature, specifically including:

[0077] The relaxation temperature is defined as 298K and the isotropic pressure is 1atm;

[0078] Define the relaxation time as 30,000 steps, that is, the relaxation time is 30 ps;

[0079] Define the system pressure, temperature and density to be output every 100 steps;

[0080] S5: Chemical crosslinking simulations are performed under the conditions of equal particle number, equal volume, equal energy and Langevin thermostat temperature control, including:

[0081] Read the chemical cross-linking reaction template file created by S2;

[0082] The maximum displacement distance of atoms in each time step is limited to

[0083] The temperature of the Langevin thermostat is defined as 298K;

[0084] The command used to define chemical crosslinking is the fixbond / react command;

[0085] The minimum threshold for each step reaction is defined as The maximum response threshold is The reactive atoms of DGEBA and AFD must be There will be a reaction between them to form bonds;

[0086] A mapping file that defines each step of the chemical cross-linking reaction;

[0087] Define the maximum number of reactive atoms to limit the degree of crosslinking. In this example, the maximum number of reactive atoms in the first step is 50, and the maximum number of reactive atoms in the second step is 46, which means that the degree of crosslinking of the chemical crosslinking system is 80%.

[0088] The chemical cross-linking reaction time is defined as 60,000 steps, i.e. the reaction time is 60 ps;

[0089] Output data file of chemical cross-linking model;

[0090] Dynamic display and analysis through OVITO software;

[0091] S6: Read the chemical cross-linking data file, minimize the energy of the system, and then relax the structure under the conditions of equal particle number, equal volume, equal energy and Langevin heat bath thermostat to further stabilize the structure. Specifically, it includes:

[0092] Set the same potential function as S2;

[0093] Read the chemical cross-linking model data file established in the previous step;

[0094] Energy minimization;

[0095] The maximum displacement distance of atoms in each time step is limited to

[0096] The temperature of the Langevin thermostat is defined as 298K;

[0097] Define the relaxation time as 30,000 steps, that is, the relaxation time is 30 ps;

[0098] Then, an annealing process is performed under an ensemble of equal particle number, equal pressure, and equal temperature, specifically including:

[0099] Define room temperature to maintain 298K;

[0100] Define the relaxation time as 30,000 steps, that is, the relaxation time is 30 ps;

[0101] The heating temperature is defined as rising from 298K to 800K;

[0102] Define the heating time as 50,000 steps, that is, the relaxation time is 50 ps;

[0103] Define high temperature holding temperature 800K;

[0104] Define the relaxation time as 30,000 steps, that is, the relaxation time is 30 ps;

[0105] The cooling temperature is defined as from 800K to 298K;

[0106] Define the relaxation time as 50,000 steps, that is, the relaxation time is 50 ps;

[0107] Define room temperature to maintain the temperature at 298K;

[0108] Define the relaxation time as 30,000 steps, that is, the relaxation time is 30 ps;

[0109] Define the output of the system pressure, temperature and density every 100 steps;

[0110] Output the data file of the model after annealing process;

[0111] S7: Read the model data file of the annealing process completed in S6 and establish a dynamic cross-linking model, specifically including:

[0112] Set the same potential function as S2;

[0113] Read the data file of the stable model after annealing in the previous step;

[0114] Generates approximately Gaussian distribution of velocity based on a temperature of 300.0K;

[0115] Energy minimization;

[0116] Read the dynamic cross-linking template file established by S2;

[0117] The maximum displacement distance of atoms in each time step is limited to

[0118] The temperature of the Langevin thermostat is defined as 298K;

[0119] The directive used to define dynamic crosslinks is the fixbond / react directive;

[0120] The minimum threshold for each step reaction is defined as The maximum response threshold is The distance between the sulfur atoms of the two disulfide bonds must be Only then will the bonds be exchanged and dynamic cross-linking reactions occur;

[0121] A mapping file that defines each step of the dynamic cross-linking reaction;

[0122] The frequency of the reaction was defined as 2 occurrences per 3000 steps;

[0123] Define the output of the coordinate position of each atom and the pressure, temperature and density of the system every 100 steps;

[0124] The dynamic cross-linking reaction time was defined as 60,000 steps, i.e., the reaction time was 60 ps, ​​during which 40 disulfide bond exchanges were performed, i.e., 40 dynamic cross-linking reactions occurred;

[0125] Output the final data file of the dynamic cross-linking model;

[0126] The dynamic cross-linking model of the glassy epoxy resin was finally obtained by dynamic display and analysis using OVITO software. Figure 6 As shown, (a) dynamic key exchange is not performed, (b) dynamic key exchange is in progress, and (c) dynamic key exchange is completed.

[0127] Through the above steps, we can draw conclusions, including:

[0128] The initial microstructure of the cross-linking model was constructed, initial parameters and potential functions were set, and relaxation was performed under different canonical ensembles. Chemical cross-linking was performed under a microcanonical ensemble of equal particle number, equal volume, and equal energy and a Langevin thermostat. After annealing to obtain a stable structure, dynamic cross-linking was performed again under a microcanonical ensemble of equal particle number, equal volume, and equal energy and a Langevin thermostat, ultimately achieving the simulation of a dynamic cross-linking model of a glass-like epoxy resin. Through molecular dynamics simulation, a dynamic covalent bond (disulfide bond) was introduced into the epoxy resin to construct a dynamic cross-linking model of a glass-like epoxy resin, simulating the dynamic bond exchange behavior of the glass-like epoxy resin. This method can achieve controllable regulation of the cross-linking degree and dynamic bond reaction, providing a research framework for subsequent research on the microscopic mechanism and thermodynamic properties of glass-like epoxy resins, and for optimizing the microstructure and self-healing properties of glass-like epoxy resins.

[0129] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. Various changes and improvements are possible without departing from the spirit and scope of the present invention, and such changes and improvements fall within the scope of the invention as claimed.

Claims

1. A molecular dynamics simulation method for constructing a dynamic crosslinking model of a glass-like epoxy resin, characterized in that: The method comprises the following steps: S1: Construct an epoxy resin and crosslinker model. According to the ratio of the reactive atoms of epoxy resin and crosslinker, epoxy resin and crosslinker are randomly filled into the simulation box to construct the initial microstructure model of the epoxy resin crosslinking system. S2: template files and mapping files for chemical crosslinking and dynamic crosslinking of epoxy resin and crosslinker; S3: setting initial parameters of the initial microstructure model, wherein the initial parameters include the spatial dimension of the microstructure model, the system unit of the microstructure model, the boundary conditions of the microstructure model, and the potential function between atoms in the microstructure model; S4: After ensuring the stability of the initial conditions of the simulation, relaxation is performed under a canonical ensemble of equal particle number, equal volume, and equal temperature; then relaxation is performed under a canonical ensemble of equal particle number, equal pressure, and equal temperature; S5: Read the chemical cross-linking template file and mapping file established in S2, perform chemical cross-linking simulation under the microcanonical ensemble of equal particle number, equal volume, equal energy and Langevin heat bath temperature control method, and output a chemical cross-linking model of epoxy resin and cross-linking agent with a certain degree of cross-linking; S6: Annealing the simulation system under a canonical ensemble of equal particle number, equal pressure, and equal temperature to eliminate the internal stress of the highly cross-linked chemically cross-linked model and further stabilize the cross-linked model structure; S7: Read the model file of the annealing process completed in S6. After ensuring the stability of the initial conditions of the simulation, read the dynamic cross-linking template file and mapping file established in S2, perform dynamic cross-linking simulation under the microcanonical ensemble of equal particle number, equal volume, and equal energy and the Langevin heat bath temperature control method, and output a dynamic cross-linking model of a glassy epoxy resin.

2. The molecular dynamics simulation method for constructing a dynamic crosslinking model of a glass-like epoxy resin according to claim 1, characterized in that: In step S1, the epoxy resin and cross-linking agent models are drawn according to the molecular structure formula, and the epoxy resin and cross-linking agent are filled into the simulation box using the Amorphous Cell module to construct an initial cross-linking model.

3. The molecular dynamics simulation method for constructing a dynamic crosslinking model of a glass-like epoxy resin according to claim 1, characterized in that: In step S2, Materials Studio software is used to output data files of the templates before and after the chemical crosslinking and dynamic crosslinking reactions, and a template file and a mapping file are created based on the schematic diagrams of the chemical crosslinking and dynamic crosslinking reactions.

4. The molecular dynamics simulation method for constructing a dynamic crosslinking model of a glass-like epoxy resin according to claim 1, characterized in that: In step S3, the system unit of the microstructure model is the real unit system; the spatial dimension of the microstructure model is 3-dimensional; and the boundary conditions of the microstructure model in the x, y, and z directions are all periodic boundaries.

5. The molecular dynamics simulation method of the dynamic crosslinking model of the glass-like epoxy resin according to claim 1, characterized in that: In step S3, the potential function adopts a consistent valence force field, which is composed of multiple parts, including bond length potential energy, bond angle potential energy, torsion potential energy, out-of-plane bending energy and non-bonded interaction, and its expression is: AND total =And bond +E angle +E torsion +E out-of-plane +E non-bonded Where E bond is the bond length potential energy, E angle is the bond angle potential energy, E torsion is the torsional potential energy, E out-of-plane is the out-of-plane bending energy, E non-bonded It is a non-bonded interaction; The bond length potential energy E bond The expression is: Where k b is the bond force constant, r is the actual bond length, and r0 is the equilibrium bond length; The bond angle potential energy E angle The expression is: Where k θ is the bond angle force constant, θ is the actual bond angle, and θ0 is the equilibrium bond angle; The torsional potential energy E torsion The expression is: In the formula is the barrier height, n is the number of periods, is the actual dihedral angle, δ is the phase angle (usually 0° or 180°); The out-of-plane bending energy E out-of-plane The expression is: Where k χ is the out-of-plane bending force constant, n is the number of periods, χ is the actual deviation from the plane, and χ0 is the equilibrium deviation from the plane; The non-bonded interactions include LJ potential (Lennard-Jones 12-6 potential) and electrostatic interaction (Coulomb potential). The expression of LJ potential is: In the formula ij is the depth of the potential energy well, σ ij is the distance between atom i and atom j when the potential energy of their interaction is exactly zero, r is the interatomic distance, r c is the cutoff radius; The expression of the electrostatic effect is: Where ε0 is the dielectric constant of vacuum, ε r is the relative dielectric constant of the medium, q i and q j are the charges of atom i and atom j, r is the interatomic distance, r c is the cutoff radius.

6. The molecular dynamics simulation method for constructing a dynamic crosslinking model of a glass-like epoxy resin according to claim 1, characterized in that: In step S4, to ensure the stability of the initial conditions of the simulation, the system is subjected to energy minimization to initialize the atomic velocity and eliminate unreasonable stress in the initial structure, and then relaxed under the canonical ensembles of equal particle number, equal volume, equal temperature and equal particle number, equal pressure, and equal temperature.

7. The molecular dynamics simulation method for constructing a dynamic crosslinking model of a glass-like epoxy resin according to claim 1, characterized in that: In step S5, after reading the template file of the chemical cross-linking reaction, the chemical cross-linking is achieved using the fix bond / react command under the conditions of equal particle number, equal volume, equal energy and the temperature control of the Langevin thermal bath.

8. The molecular dynamics simulation method for constructing a dynamic crosslinking model of a glass-like epoxy resin according to claim 1, characterized in that: In step S6, the annealing process specifically includes: first maintaining at room temperature for a period of time, then gradually heating from room temperature to a high temperature of 750-850K, and maintaining at high temperature for a period of time, then gradually cooling from high temperature to room temperature, and finally briefly balancing the system at room temperature.

9. The molecular dynamics simulation method for constructing a dynamic crosslinking model of a glass-like epoxy resin according to claim 1, characterized in that: In step S7, after reading the stabilized model file after annealing and the template file of the dynamic crosslinking reaction, dynamic crosslinking is achieved using the fix bond / react command under the conditions of equal particle number, equal volume, equal energy and Langevin thermostat temperature control.

10. The molecular dynamics simulation method for constructing a dynamic crosslinking model of a glass-like epoxy resin according to claim 1, wherein the model construction process of the method is implemented using Materials Studio software, the chemical crosslinking and dynamic crosslinking simulation processes are implemented using LAMMPS software, and dynamic display and analysis are performed using OVITO software.

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