A multi-dynamic key synergistic self-repairing polyurethane and a preparation method thereof

Abstract

The present application relates to a kind of polyurethane of multiple dynamic key cooperation self-repair and its preparation method, belong to polyurethane technical field.The raw material composition of the polyurethane includes polyglycol, diisocyanate, pyridine chain extender, catechol and ferric ion salt.The main chain of the polyurethane is formed by polyglycol and diisocyanate after chain extension by pyridine chain extender, end group is by catechol group exposed by catechol substance end capping, ferric ion is formed metal coordination bond with catechol group on one hand, and is formed coordination bond with the nitrogen atom on pyridine on the other hand;Multiple dynamic key is included in the polyurethane, including the coordination bond of pyridine and iron ion, the coordination bond of catechol and iron ion, the hydrogen bond between polymer chain.When being subjected to external pressure, due to the internal friction of molecular chain, material has good damping capacity;Meanwhile, the polyurethane has good self-repairing capacity at room temperature.

Description

Technical Field

[0001] This invention relates to a multi-dynamic bond synergistic self-healing polyurethane and its preparation method, belonging to the field of polyurethane technology. Background Technology

[0002] Damping materials are a class of materials capable of absorbing and dispersing vibrational energy. They are widely used in engineering structures, automobiles, aerospace, and other fields to reduce vibration and noise, and improve structural stability and comfort. Self-healing materials are a class of materials with self-repairing capabilities, capable of automatically repairing themselves after damage, extending the material's service life and reducing maintenance costs. The research and development of materials possessing both damping and self-healing properties is of great significance for improving the functionality and performance of materials and promoting the development of materials science and engineering technology.

[0003] Significant progress has been made in the research of damping materials over the past few decades. Traditional damping materials mainly include metallic damping materials, polymer damping materials, and composite damping materials. However, the performance of traditional damping materials is often unstable under harsh environments such as high temperature and high humidity, and they are prone to fatigue and aging during long-term use, limiting their application in practical engineering. Therefore, seeking a new type of damping material has significant research significance and application value.

[0004] Self-healing materials have become a research hotspot in materials science in recent years. Traditional self-healing materials mainly include microcapsule self-healing materials, conductive self-healing materials, and chemically reactive self-healing materials. These materials possess certain self-healing capabilities, but are often limited by issues such as material volume changes and low repair efficiency, making it difficult to achieve self-healing functions under dynamic loading conditions. Therefore, developing a novel self-healing material with efficient self-healing performance and excellent dynamic mechanical properties is of great significance for promoting the application and development of self-healing materials.

[0005] High-damping self-healing polyurethane, as a novel damping material, possesses unique advantages and potential application prospects. Firstly, this material exhibits excellent damping performance, effectively absorbing and dispersing energy under dynamic loading, reducing structural vibration and noise. Secondly, it also possesses good self-healing properties, capable of automatically repairing itself after damage, extending the material's service life and reducing maintenance costs. Combining these advantages, materials possessing both damping and self-healing properties have broad application prospects and significant value in fields such as construction, transportation, and aerospace. However, existing high-damping self-healing materials still face some bottlenecks. The preparation of high-damping self-healing polyurethane materials requires precise control of the material's composition, structure, and micromorphology to ensure it simultaneously possesses excellent damping performance and self-healing capabilities. This demands highly precise and stable preparation processes, but current technology is insufficient to fully meet this requirement. While pursuing high damping performance, it is also necessary to ensure the material's self-healing efficiency, mechanical properties, and durability. These properties often have interdependent relationships, making performance optimization particularly difficult. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a multi-dynamic bond synergistic self-healing polyurethane and its preparation method. This polyurethane contains multiple dynamic bonds, including coordination bonds between pyridine and iron ions, coordination bonds between catechol and iron ions, and hydrogen bonds between polymer chains. Under external pressure, the material exhibits good damping capacity due to the internal frictional forces within the molecular chains; simultaneously, this polyurethane possesses excellent self-healing capabilities at room temperature.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows.

[0008] A multi-dynamic bond synergistic self-healing polyurethane, wherein the raw material composition of the polyurethane includes polydiol, diisocyanate, pyridine chain extender, catechol, and ferric salt. Based on the total mass of the polydiol, diisocyanate, pyridine chain extender, and catechol as 100%, the mass fraction of the polydiol is 46.65%–54.24%, the mass fraction of the diisocyanate is 25.91%–32.51%, the mass fraction of the pyridine chain extender is 9.72%–13.59%, and the mass fraction of the catechol is 7.69%–14.91%; the molar ratio of ferric ions, pyridine chain extender, and catechol is 1:2:3.

[0009] Preferably, the main chain of the polyurethane is formed by chain extension of polydiol and diisocyanate using a pyridine chain extender, and the end groups are exposed catechol groups after end capping with catechol-based substances. Ferric ions form metal-coordinate bonds with the catechol groups on one hand, and coordinate bonds with the nitrogen atoms on the pyridine on the other hand; wherein the coordination relationship between the ferric ions and the catechol groups is as follows: The coordination relationship of ferric ion pyridine is as follows

[0010] Preferably, the polydiol is one or more of polybutanediol (PTMG), polypropylene glycol (PPG), and polyethylene glycol (PEG).

[0011] Preferably, the molecular weight of the polydiol is 1500 to 3000.

[0012] Preferably, the diisocyanate is one or more selected from toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), and L-lysine diisocyanate (LDI).

[0013] Preferably, the pyridine chain extender is 2,6-pyridinediethanol or 2,6-pyridinedimethylamine.

[0014] Preferably, the catechol is one or more of dopamine (DA), isoproterenol (ISO), ellagic acid (EA), and quercetin (QR).

[0015] Preferably, the ferric salt is one or more of nitrate, carboxylate, and chloride.

[0016] Preferably, the polyurethane has a tensile strength of 0.9–3.5 MPa, a damping factor of 0.4602–0.5718, and an elongation at break of 1100%–1580%.

[0017] A method for preparing a multi-dynamic bond synergistic self-healing polyurethane according to the present invention includes the following steps:

[0018] (1) Under nitrogen protection, the dehydrated polydiol, diisocyanate and anhydrous toluene are mixed and stirred at 80-85°C for 3-4 hours to obtain the prepolymer;

[0019] (2) Add an anhydrous toluene solution of pyridine chain extender to the prepolymer and continue stirring at 80-85°C for 8-10 hours to obtain a pyridine chain-extended polymer solution.

[0020] (3) Add anhydrous toluene solution of catechol to the polymer solution and stir at 45-55°C for 12-14 hours to obtain polyurethane matrix prepolymer solution.

[0021] (4) Add the polyurethane matrix prepolymer solution to the ferric ion salt solution, stir for 20-30 minutes, pour into a mold, and cure at 75-85℃ for more than 7 days to obtain a polyurethane with multiple dynamic bonds synergistic self-healing.

[0022] Beneficial effects

[0023] This invention provides a multi-dynamic bond synergistic self-healing polyurethane. The polyurethane elastomer uses 2,6-pyridinediethanol as a chain extender, and the end groups are composed of dopamine-capped, exposed catechol. Iron ions play two roles: firstly, as a metal ligand with catechol, they form metal-coordinate bonds with the catechol groups at the polymer chain ends. These metal-coordinate bonds, as dynamic chemical bonds, can break when the material is damaged and reform when the broken surfaces are repaired. Secondly, as a ligand for the pyridine ring, the lone pair electrons on the nitrogen atom of pyridine can enter the empty orbitals of the iron ion, thus forming a coordinate bond; this pyridine-iron ion coordination is also a dynamic chemical bond. Because iron ions bring a large number of dynamic chemical bonds into the elastomer, this multi-level dynamic chemical bonding endows the material with strong self-healing capabilities.

[0024] This invention provides a polyurethane with synergistic self-healing properties of multiple dynamic bonds. Ferrous ions can simultaneously form coordination bonds with pyridine and catechol substances, thereby forming a complex cross-linked network. The high density of multi-level dynamic chemical bonds inside the polyurethane elastomer gives the material a high self-healing efficiency. Furthermore, due to the large number of dynamic chemical bonds inside the polyurethane elastomer, the molecular chain has strong mobility and high friction, resulting in good damping performance of the material. Attached Figure Description

[0025] Figure 1 The reaction process is for steps (1)-(4) in Example 1.

[0026] Figure 2 The results are infrared test results of the PDM / DA-FePU in Example 1.

[0027] Figure 3 The stress-strain curves of polyurethane in Comparative Examples 1-2 and Example 1 are shown.

[0028] Figure 4 The dynamic thermomechanical curves of polyurethane in Comparative Example 1 and Example 1 are shown.

[0029] Figure 5 The stress-strain curves before and after PDM / DA-FePU self-healing in Example 1 are shown. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to specific embodiments.

[0031] Comparative Example 1

[0032] In this comparative example, the molecular weight of polybutanediol is 1000.

[0033] (1) Under nitrogen protection, 20g of polybutadiene glycol was added to a 250ml three-necked flask, heated to 120℃, and stirred at a rate of 200r / min for 4h under reduced pressure to remove moisture. Then it was allowed to stand at room temperature to obtain dehydrated polybutadiene glycol.

[0034] (2) Measure 11.11g of isophorone diisocyanate into the three-necked flask in step (1), add 100ml of anhydrous toluene to dissolve the raw material, add 0.02g of dibutyltin dilaurate, heat to 80℃, stir at a rate of 200r / min, and react for 4h to obtain the prepolymer solution.

[0035] (3) Take 4.17g of 2,6-pyridinediethanol powder, dissolve it in 10ml of anhydrous toluene, wait for it to dissolve, add it to a three-necked flask, and continue to react at 80℃ and 200r / min for 8h to obtain a pale yellow transparent liquid.

[0036] (4) Take 2.012g of dopamine hydrochloride into 10ml of anhydrous toluene, stir to dissolve, then measure 1.08g of triethylamine to adjust the pH value, let the solution in step (3) stand to 50℃, then add the dissolved dopamine hydrochloride / triethylamine mixed solution, react at 150r / min and 50℃ for 24h to obtain a light yellow transparent liquid.

[0037] (5) Pour the pale yellow liquid obtained in step (4) into a polytetrafluoroethylene mold, put it in an oven at 80°C for 24 hours to remove a large amount of toluene, and then put it in a vacuum oven at 80°C for 3 days to obtain a pale yellow transparent polyurethane elastomer film PDM / DA-PU.

[0038] Infrared spectroscopy revealed the following structural formula for the PDM / DA-PU, where m represents the degree of polymerization of polybutanediol:

[0039]

[0040] Comparative Example 2

[0041] In this comparative example, the molecular weight of polybutanediol is 1000.

[0042] (1) Under nitrogen protection, 20g of polybutadiene glycol was added to a 250ml three-necked flask, heated to 120℃, and stirred at a rate of 200r / min for 4h under reduced pressure to remove moisture. Then it was allowed to stand at room temperature to obtain dehydrated polybutadiene glycol.

[0043] (2) Measure 11.11g of isophorone diisocyanate into the three-necked flask in step (1), add 100ml of anhydrous toluene to dissolve the raw material, add 0.02g of dibutyltin dilaurate, heat to 80℃, stir at a rate of 200r / min, and react for 4h to obtain the prepolymer solution.

[0044] (3) Take 4.17g of 2,6-pyridinediethanol powder, dissolve it in 10ml of anhydrous toluene, wait for it to dissolve, add it to a three-necked flask, and continue to react at 80℃ and 200r / min for 8h to obtain a pale yellow transparent liquid.

[0045] (4) Dissolve 2.42g of anhydrous ferric chloride in anhydrous toluene, wait for the temperature of the solution in step (3) to drop to room temperature, add it to a three-necked flask, and stir at 200r / min for 20min at room temperature.

[0046] (5) Pour the black liquid obtained in step (4) into a polytetrafluoroethylene mold, put it in an oven at 80°C for 24 hours to remove a large amount of toluene, and then put it in a vacuum oven at 80°C for 3 days to obtain a black polyurethane elastomer film, denoted as PDM-FePU.

[0047] Infrared spectroscopy revealed the following main chain structure of the PDM-FePU, where n represents the degree of polymerization of polybutanediol:

[0048]

[0049] The coordination relationship between iron ions and pyridine is as follows:

[0050]

[0051] Example 1

[0052] In this embodiment, the molecular weight of polybutanediol is 1000.

[0053] (1) Under nitrogen protection, 20g of polybutadiene glycol was added to a 250ml three-necked flask, heated to 120℃, and stirred at a rate of 200r / min for 4h under reduced pressure to remove moisture. Then it was allowed to stand at room temperature to obtain dehydrated polybutadiene glycol.

[0054] (2) Measure 11.11g of isophorone diisocyanate into the three-necked flask in step (1), add 100ml of anhydrous toluene to dissolve the raw material, add 0.02g of dibutyltin dilaurate, heat to 80℃, stir at a rate of 200r / min, and react for 4h to obtain the prepolymer solution.

[0055] (3) Take 2.085g of 2,6-pyridinediethanol powder, dissolve it in 10ml of anhydrous toluene, wait for it to dissolve, add it to a three-necked flask, and continue to react at 80℃ and 200r / min for 8h to obtain a pale yellow transparent liquid.

[0056] (4) Take 1.896g of dopamine hydrochloride into 10ml of anhydrous toluene, stir to dissolve, then measure 1.01g of triethylamine to adjust the pH value, let the solution in step (3) stand to 50℃, then add the dissolved dopamine hydrochloride / triethylamine mixed solution, react at 150r / min and 50℃ for 24h to obtain a light yellow transparent liquid.

[0057] (5) Dissolve 2.12g of anhydrous ferric chloride in anhydrous toluene, wait for the temperature of the solution in step (4) to drop to room temperature, add it to a three-necked flask, and stir at 200r / min for 20min at room temperature.

[0058] (6) Pour the black liquid from step (5) into a polytetrafluoroethylene mold, place it in an oven at 80°C for 24 hours to remove a large amount of toluene, and then place it in a vacuum oven at 80°C for 3 days to obtain a black polyurethane elastomer film, denoted as PDM / DA-FePU.

[0059] The reaction flow of steps (1)-(4) is as follows: Figure 1 As shown.

[0060] like Figure 2 As shown, the structural formula of the PDM / DA-FePU, as determined by infrared testing, is as follows:

[0061]

[0062] The main chain structure is as follows:

[0063]

[0064] The coordination relationships of iron ions are as follows:

[0065] Example 2

[0066] In this embodiment, the molecular weight of polybutanediol is 1700.

[0067] (1) Under nitrogen protection, 34g of polybutadiene glycol was added to a 250ml three-necked flask, heated to 120℃, and stirred at a rate of 200r / min for 4h under reduced pressure to remove moisture. Then it was allowed to stand at room temperature to obtain dehydrated polybutadiene glycol.

[0068] (2) Measure 10.92g of isophorone diisocyanate into the three-necked flask in step (1), add 100ml of anhydrous toluene to dissolve the raw material, add 0.02g of dibutyltin dilaurate, heat to 80℃, stir at a rate of 200r / min, and react for 4h to obtain the prepolymer solution.

[0069] (3) Take 2.045g of 2,6-pyridinediethanol powder, dissolve it in 10ml of anhydrous toluene beforehand, wait for it to dissolve, add it to a three-necked flask, and continue to react at 80℃ and 200r / min for 8h to obtain a pale yellow transparent liquid.

[0070] (4) Take 1.916g of dopamine hydrochloride into 10ml of anhydrous toluene, stir to dissolve, then measure 1.12g of triethylamine to adjust the pH value, let the solution in step (3) stand to 50℃, then add the dissolved dopamine hydrochloride / triethylamine mixed solution, react at 150r / min and 50℃ for 24h to obtain a light yellow transparent liquid.

[0071] (5) Dissolve 2.24g of anhydrous ferric chloride in anhydrous toluene, wait for the temperature of the solution in step (4) to drop to room temperature, add it to a three-necked flask, and stir at 200r / min for 20min at room temperature.

[0072] (6) Pour the black liquid from step (5) into a polytetrafluoroethylene mold, place it in an oven at 80°C for 24 hours to remove a large amount of toluene, and then place it in a vacuum oven at 80°C for 3 days to obtain a black polyurethane elastomer film, denoted as PDM / DA-FePU-2.

[0073] The structure of the PDM / DA-FePU-2 is similar to that of Example 1, except that it differs only in the degree of polymerization of polybutanediol.

[0074] Example 3

[0075] In this embodiment, the molecular weight of polybutanediol is 2000.

[0076] (1) Under nitrogen protection, 40g of polybutadiene glycol was added to a 250ml three-necked flask, heated to 120℃, and stirred at a rate of 200r / min for 4h under reduced pressure to remove moisture. Then it was allowed to stand at room temperature to obtain dehydrated polybutadiene glycol.

[0077] (2) Measure 11.12g of isophorone diisocyanate into the three-necked flask in step (1), add 100ml of anhydrous toluene to dissolve the raw material, add 0.02g of dibutyltin dilaurate, heat to 80℃, stir at a rate of 200r / min, and react for 4h to obtain the prepolymer solution.

[0078] (3) Take 2.055g of 2,6-pyridinediethanol powder, dissolve it in 10ml of anhydrous toluene, wait for it to dissolve, add it to a three-necked flask, and continue to react at 80℃ and 200r / min for 8h to obtain a pale yellow transparent liquid.

[0079] (4) Take 1.926g of dopamine hydrochloride into 10ml of anhydrous toluene, stir to dissolve, then measure 1.12g of triethylamine to adjust the pH value, let the solution in step (3) stand to 50℃, then add the dissolved dopamine hydrochloride / triethylamine mixed solution, react at 150r / min and 50℃ for 24h to obtain a light yellow transparent liquid.

[0080] (5) Dissolve 2.34g of anhydrous ferric chloride in anhydrous toluene, wait for the solution temperature in step (4) to drop to room temperature, add it to a three-necked flask, and stir at 200r / min for 20min at room temperature.

[0081] (6) Pour the black liquid from step (5) into a polytetrafluoroethylene mold, place it in an oven at 80°C for 24 hours to remove a large amount of toluene, and then place it in a vacuum oven at 80°C for 3 days to obtain a black polyurethane elastomer film, denoted as PDM / DA-FePU-3.

[0082] The structure of the PDM / DA-FePU-3 is similar to that of Example 1, the only difference being the degree of polymerization of polybutanediol.

[0083] Example 4

[0084] In this embodiment, the molecular weight of polyethylene glycol is 2000.

[0085] (1) Under nitrogen protection, 36g of polyethylene glycol was added to a 250ml three-necked flask, heated to 120℃, and stirred at a rate of 200r / min under reduced pressure for 4h to remove moisture. Then it was allowed to stand at room temperature to obtain dehydrated polyethylene glycol.

[0086] (2) Measure 11.08g of isophorone diisocyanate into the three-necked flask in step (1), add 100ml of anhydrous toluene to dissolve the raw material, add 0.02g of dibutyltin dilaurate, heat to 80℃, stir at a rate of 200r / min, and react for 4h to obtain the prepolymer solution.

[0087] (3) Take 2.045g of 2,6-pyridinediethanol powder, dissolve it in 10ml of anhydrous toluene beforehand, wait for it to dissolve, add it to a three-necked flask, and continue to react at 80℃ and 200r / min for 8h to obtain a pale yellow transparent liquid.

[0088] (4) Take 1.856g of dopamine hydrochloride into 10ml of anhydrous toluene, stir to dissolve, then measure 0.98g of triethylamine to adjust the pH value, let the solution in step (3) stand to 50℃, then add the dissolved dopamine hydrochloride / triethylamine mixed solution, react at 150r / min and 50℃ for 24h to obtain a light yellow transparent liquid.

[0089] (5) Dissolve 2.14g of anhydrous ferric chloride in anhydrous toluene, wait for the temperature of the solution in step (4) to drop to room temperature, add it to a three-necked flask, and stir at 200r / min for 20min at room temperature.

[0090] (6) Pour the black liquid from step (5) into a polytetrafluoroethylene mold, place it in an oven at 80°C for 24 hours to remove a large amount of toluene, and then place it in a vacuum oven at 80°C for 3 days to obtain a black polyurethane elastomer film, denoted as PDM / DA-FePU-6.

[0091] Comparative Example 3

[0092] The difference between this comparative example and Example 1 is that the amount of anhydrous ferric chloride used is 3.00g.

[0093] Tensile tests were performed on the final products prepared in the examples and comparative examples. The test conditions were as follows: using a 500N force sensor, cutting the samples with a 4mm*50mm dumbbell-shaped cutter, and conducting the test at a tensile rate of 20mm / min. The results are as follows. Figure 3 As shown, the strength of polyurethane elastomers using pyridine chain extension is positively correlated with the pyridine content in the main chain. Furthermore, iron ions can act as crosslinking points to further enhance the material's strength. This indicates that the iron-crosslinked polyurethane elastomer based on pyridine chain extension can serve as a synthesis method for a class of polyurethane elastomers, improving their mechanical properties. The addition of iron ions can improve the material's strength and elongation at break, demonstrating that iron ion-pyridine coordination and the introduction of iron ion-catechol are beneficial for enhancing material strength.

[0094] Damping performance tests were conducted on the final products prepared in the examples and comparative examples. Specifically, a piece of prepared PDM / DA-FePU was cut into 10mm*10mm strips using a cutter. Dynamic mechanical analysis (DMA) tests were then performed in air. The samples were fixed with shear clamps. The experiment used a dynamic temperature scan mode. The heating rate was set to 3℃ / min. The frequency was set to 10Hz to evaluate the thermodynamic behavior of the samples between -80℃ and 80℃. The results are as follows: Figure 4 As shown.

[0095] The final product prepared in the example was subjected to a tensile self-healing test. The specific implementation method was as follows: a piece of prepared PDM / DA-FePU was taken and cut into a dumbbell shape with a cutter. Then, the middle part was cut off with a knife, and then the pieces were tightly bonded together for 10 seconds. It was found that there were no obvious cut marks at the break point. At this time, it can be considered that the sample has completed the self-healing process. The results are as follows. Figure 5 As shown.

[0096] The results from Example 1 and Comparative Example 3 show that as the iron ion concentration increases, new coordination bonds are continuously generated in the system, the crosslinking point density increases, and the mechanical properties improve. However, once all the catechols and pyridines have formed stable coordination relationships with the iron ions, the iron ions added later do not have coordination groups that can adapt to them. Therefore, they can only exist in the elastomer in the form of small molecules, acting as "plasticizers," which leads to a decrease in the mechanical properties of the material.

[0097] The self-healing performance of PDM / DA-FePU-1 at 25°C in Example 1 is shown in Table 1.

[0098] Table 1

[0099]

[0100] The performance results of the materials obtained in the examples and comparative examples are shown in Table 2.

[0101] Table 2

[0102]

[0103] The performance results of the materials obtained in the examples and comparative examples are shown in Table 3.

[0104] Table 3

[0105] Types of soft segments Soft segment molecular weight Damping factor PDM / DA-FePU-1 Polybutanediol 1000 0.5718 PDM / DA-FePU-2 Polybutanediol 1700 0.5374 PDM / DA-FePU-3 Polybutanediol 2000 0.4861 PDM / DA-FePU-4 polyethylene glycol 2000 0.4725 PDM / DA-PU Polybutanediol 1000 0.4602

[0106] In summary, the invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered to be within the protection scope of this invention.

Claims

1. A multi-dynamic-key synergistic self-healing polyurethane, characterized in that: The raw material composition of the polyurethane comprises a polyhydric alcohol, a diisocyanate, a pyridine chain extender, a catechol, and a ferric ion salt, wherein the mass fraction of the polyhydric alcohol is 46.65% to 54.24%, the mass fraction of the diisocyanate is 25.91% to 32.51%, the mass fraction of the pyridine chain extender is 9.72% to 13.59%, and the mass fraction of the catechol is 7.69% to 14.91%, based on the total mass of the polyhydric alcohol, the diisocyanate, the pyridine chain extender, and the catechol being 100%; the molar ratio of the ferric ion, the pyridine chain extender, and the catechol is 1:2:

3. The pyridine chain extender is 2,6-pyridine dimethyl alcohol or 2,6-pyridine dimethyl amine. The polyurethane is prepared by the following method, and the method steps comprise: (1) under nitrogen protection, mixing the dehydrated polyhydric alcohol, the diisocyanate, and anhydrous toluene, and stirring and reacting at 80 to 85°C for 3 to 4 hours to obtain a prepolymer; (2) adding a pyridine chain extender anhydrous toluene solution to the prepolymer, and continuing to stir and react at 80 to 85°C for 8 to 10 hours to obtain a pyridine chain-extended high molecular polymer solution; (3) adding a catechol anhydrous toluene solution to the high molecular polymer solution, and stirring and reacting at 45 to 55°C for 12 to 14 hours to obtain a polyurethane matrix prepolymer solution; (4) adding the polyurethane matrix prepolymer solution to a ferric ion salt solution, stirring for 20 to 30 minutes, pouring into a mold, and curing at 75 to 85°C for more than 7 days to obtain a polyurethane with multiple dynamic bonds and synergistic self-repairing.

2. The multi-dynamic key synergistically self-healing polyurethane according to claim 1, characterized in that: The main chain of the polyurethane is formed by chain extension of polyglycol and diisocyanate by a pyridine chain extender, and the exposed pyrocatechol group of the pyrocatechol group capped by the pyrocatechol group, the trivalent iron ion forms a metal coordination bond with the pyrocatechol group on one hand, and forms a coordination bond with the nitrogen atom on the pyridine on the other hand; wherein the coordination relationship between the iron ion and the pyrocatechol group is ; the coordination relationship between the iron ion and the pyridine is .

3. The multi-dynamic bond synergistically self-healing polyurethane according to claim 1 or 2, characterized in that: The polyhydric alcohol is one or more of polybutylene glycol, polypropylene glycol, and polyethylene glycol.

4. The multi-dynamic bond synergistically self-healing polyurethane according to claim 1 or 2, characterized in that: The molecular weight of the polyhydric alcohol is 1500 to 3000.

5. The multi-dynamic bond synergistically self-healing polyurethane according to claim 1 or 2, characterized in that: The diisocyanate is one or more of toluene diisocyanate, isophorone diisocyanate, diphenyl methane diisocyanate, dicyclohexyl methane diisocyanate, hexamethylene diisocyanate, and L-lysine diisocyanate.

6. The multi-dynamic bond synergistically self-healing polyurethane according to claim 1 or 2, characterized in that: The catechol is one or more of dopamine, isopropyl adrenaline, ellagic acid, and quercetin.

7. The multi-dynamic bond synergistically self-healing polyurethane according to claim 1 or 2, wherein: The ferric ion salt is one or more of a nitrate, a carboxylate, and a chloride.

8. The multi-dynamic bond synergistically self-healing polyurethane according to claim 1 or 2, characterized in that: The tensile strength of the polyurethane is 0.9 to 3.5 MPa, the damping factor is 0.4602 to 0.5718, and the elongation at break is 1100% to 1580%.

9. A method for preparing a polyurethane with multiple dynamic bonds and synergistic self-repairing according to any one of claims 1 to 8, and the method steps comprise: (1) under nitrogen protection, mixing the dehydrated polyhydric alcohol, the diisocyanate, and anhydrous toluene, and stirring and reacting at 80 to 85°C for 3 to 4 hours to obtain a prepolymer; (2) adding a pyridine chain extender anhydrous toluene solution to the prepolymer, and continuing to stir and react at 80 to 85°C for 8 to 10 hours to obtain a pyridine chain-extended high molecular polymer solution; (3) adding a catechol anhydrous toluene solution to the high molecular polymer solution, and stirring and reacting at 45 to 55°C for 12 to 14 hours to obtain a polyurethane matrix prepolymer solution; (4) adding the polyurethane matrix prepolymer solution to a ferric ion salt solution, stirring for 20 to 30 minutes, pouring into a mold, and curing at 75 to 85°C for more than 7 days to obtain a polyurethane with multiple dynamic bonds and synergistic self-repairing. (4) the polyurethane matrix prepolymer solution is added into the ferric ion salt solution, stirred for 20-30 min, poured into a mold, and cured at 75-85 DEG C for more than 7 days to obtain a polyurethane with multiple dynamic bonds and synergistic self-repairing.

Images