Supramolecular polyurethane elastomer as well as preparation method and application thereof

Abstract

The invention discloses a supramolecular polyurethane elastomer as well as a preparation method and application thereof, and the elastomer is prepared from the following raw materials in parts by weight: 100 parts of polyhydric alcohol, 30-50 parts of diisocyanate, 8-15 parts of a chain extender, 1-5 parts of 3, 3 '-diphenyl-1, 3-pentanediol monoisobutyrate, 1-5 parts of an antioxidant and 1-5 parts of a catalyst. The chain extender is a furan-maleimide derivative containing a Diels-Alder bond, the molecular structure of the furan-maleimide derivative contains two hydroxyl end groups, and the chain extender is a furan-maleimide derivative containing a Diels-Alder bond, the molecular structure of the furan-maleimide derivative contains two hydroxyl end groups, and the molecular structure of the 3, 4-dihydroxybenzaldehyde ethylenediamine is a furan-maleimide derivative containing a Diels-Alder bond. The molecular structure of the 1, 4-dihydroxy benzaldehyde ethylenediamine contains catechol groups and amino groups, the subject-object compound is formed by compounding alpha-cyclodextrin and adamantane methanol according to the molar ratio of 1: 1, and the mechanochromic unit is a diol derivative containing azobenzene side groups.

Description

Technical Field

[0001] This invention relates to the field of supramolecular materials technology, specifically to a supramolecular polyurethane elastomer, its preparation method, and its applications. Background Technology

[0002] As the core equipment for transporting corrosive media, chemical pipelines need to withstand multiple effects of mechanical impact, stress fatigue and chemical corrosion during service. These factors can easily lead to micro-cracks in the pipeline, and in severe cases, even leakage, which can cause safety accidents. Therefore, stringent requirements are placed on the performance of pipeline materials.

[0003] Supramolecular polyurethane elastomers, with their dynamic non-covalent reversible recombination properties, have shown significant potential in solving pipeline damage repair problems and have become one of the key materials in this field. Their dynamic bond energy can break and recombine under external conditions, providing the possibility for pipeline self-repair, and is expected to extend pipeline service life and reduce maintenance costs.

[0004] However, existing supramolecular polyurethane materials in the industry still have significant technical shortcomings, making it difficult to fully meet the complex operating conditions of chemical pipelines. While some existing supramolecular polyurethane materials improve mechanical strength and room-temperature self-healing performance through the synergistic effect of metal coordination bonds and hydrogen bonds, they generally lack damage warning functions. When pipelines suffer hidden micro-damage due to stress, the materials cannot provide visual signals (such as color changes) to indicate the damage, making it difficult to detect in a timely manner and delaying maintenance. Furthermore, some supramolecular polyurethane materials rely on self-healing systems built around single hydrogen bond interactions, which are highly sensitive to temperature. Under the high-temperature conditions common in chemical pipelines above 80°C (such as transporting high-temperature reaction media), hydrogen bonds easily dissociate, leading to a sharp drop in self-healing efficiency and loss of effective repair capabilities. In addition, existing technologies also employ nanoparticle-reinforced modified polyurethane materials, which, while optimizing wear resistance, have a relatively simple dynamic repair network structure, especially when in contact with Cl-containing substances. - When exposed to highly corrosive media, corrosion not only erodes the material surface but also damages the internal dynamic repair network, causing the self-healing function to fail. At the same time, it accelerates material aging and shortens the service life of the pipeline. Summary of the Invention

[0005] The purpose of this invention is to provide a supramolecular polyurethane elastomer, its preparation method, and its application, so as to solve the above-mentioned problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a supramolecular polyurethane elastomer, said elastomer being prepared from the following raw materials in parts by weight: 100 parts of polyol, 30-50 parts of diisocyanate, 8-15 parts of chain extender, 5-12 parts of 3,4-dihydroxybenzaldehyde ethylenediamine, 3-8 parts of host-guest complex, 2-5 parts of mechanochromic unit, 1-3 parts of metal salt, 0.1-0.5 parts of catalyst, and 50-100 parts of solvent, wherein the chain extender is a furan-maleimide derivative containing Diels-Alder bonds, the molecular structure of which contains two hydroxyl terminal groups, the molecular structure of 3,4-dihydroxybenzaldehyde ethylenediamine contains catechol groups and amino groups, the host-guest complex is composed of α-cyclodextrin and adamantane methanol in a 1:1 molar ratio, and the mechanochromic unit is a diol derivative containing azobenzene side groups.

[0007] In one embodiment, the preparation method of furan-maleimide derivative containing Diels-Alder bonds is as follows: furanol and maleimide are reacted at 80°C for 4-6 h at a molar ratio of 1.2:1, and the furan-maleimide derivative containing Diels-Alder bonds is obtained after purification by column chromatography, and the dissociation temperature of the Diels-Alder bonds is 120-140°C.

[0008] In one embodiment, the azophenyl group in the molecular structure of the diol derivative containing the azophenyl side group is connected to the diol backbone through a spacer group. The spacer group has 2-4 carbon atoms and can undergo cis-trans isomerization under stress of 5-50 MPa, resulting in a color change.

[0009] In one embodiment, the polyol is selected from at least one of polybutylene adipate diol and polytetrahydrofuran ether diol with a number average molecular weight of 2000-4000.

[0010] In one embodiment, the diisocyanate is selected from at least one of 4,4'-diphenylmethane diisocyanate and hexamethylene diisocyanate.

[0011] In one embodiment, the metal salt is selected from at least one of ferric chloride and zinc acetate.

[0012] In one embodiment, the catalyst is dibutyltin dilaurate.

[0013] In one embodiment, the solvent is selected from at least one of N,N-dimethylformamide and tetrahydrofuran.

[0014] In a second aspect, the present invention provides a method for preparing a supramolecular polyurethane elastomer, comprising the following steps: S1: Add the metal salt to the solvent and stir at a rate of 400-600 rpm until completely dissolved to obtain a metal salt solution; S2: The polyol is vacuum dehydrated at 100-120℃ for 2-3 hours, then cooled to 60-70℃ and diisocyanate and catalyst are added. Under nitrogen protection, the mixture is stirred at 300-500 rpm for 1.5-2.5 hours to obtain the prepolymer. S3: Add chain extender, 3,4-dihydroxybenzaldehyde ethylenediamine and metronic color-changing unit sequentially to the prepolymer, heat to 75-85℃, stir at 300-500 rpm for 1-2 h, add host-guest complex, continue stirring at 300-500 rpm for 0.5-1 h, then cool to 40-50℃, add metal salt solution dropwise, and after the addition is complete, keep stirring at 300-500 rpm for 1-1.5 h to obtain reaction solution; S4: Pour the reaction solution into a polytetrafluoroethylene mold, pre-cur at 80°C for 4 hours, and then post-cur at 100°C for 8-12 hours. After demolding, the elastomer is obtained.

[0015] In a third aspect, the present invention provides an application of supramolecular polyurethane elastomer in chemical pipelines.

[0016] In summary, the beneficial effects of this invention are: 1. The elastomer raw material of this invention uses a diol derivative containing azobenzene side groups as the mechanochromic unit. In its molecular structure, the azophenyl group is connected to the diol main chain through spacer groups with 2-4 carbon atoms. The spacer group can efficiently transfer the stress generated by mechanical impact and medium pressure during the service of chemical pipelines. When the stress is 5-50 MPa, the azophenyl group will undergo cis-trans isomerization transformation, which manifests as a color change. It can be used to monitor the hidden micro-damage caused by stress in pipelines in real time.

[0017] 2. The chain extender in the elastomer raw material of this invention is a furan-maleimide derivative containing Diels-Alder bonds. Its Diels-Alder bond dissociation temperature is 120-140℃. It can quickly dissociate and recombine at high temperatures to replenish repair sites. The host-guest complex is composed of α-cyclodextrin and adamantane methanol in a 1:1 molar ratio. It can achieve self-repair at room temperature through dynamic inclusion between molecular chains. The catechol group in the 3,4-dihydroxybenzaldehyde ethylenediamine molecule forms metal coordination bonds with metal salts (ferric chloride, zinc acetate), further strengthening the repair interface and improving repair stability. This ensures that the elastomer can maintain high efficiency self-repair capability in both room temperature and high temperature (such as 120℃) environments, effectively extending the service life of chemical pipelines and reducing maintenance costs.

[0018] 3. The furan-maleimide derivative containing Diels-Alder bonds in the elastomer raw material of this invention can provide reversible covalent crosslinking, which can improve the rigidity of the molecular chain. The host-guest complex can build dynamic connections between molecular chains and retain the flexibility of the chain segments. 3,4-Dihydroxybenzaldehyde ethylenediamine and metal salts (ferric chloride, zinc acetate) can form metal coordination bonds, which further strengthens the inter-chain bonding force, so that the elastomer has both high tensile strength and high elongation at break.

[0019] 4. This invention utilizes the reversible covalent cross-linking of Diels-Alder bonds, the dynamic inclusion of host-guest complexes, and metal coordination bonds to synergistically form a dense cross-linked network, which can effectively block Cl. - Corrosion ion penetration slows down the degradation rate of molecular chains, while the catechol groups in 3,4-dihydroxybenzaldehyde ethylenediamine react with Fe. 3+ Zn 2+ It forms a stable coordination structure, avoids the dissociation and loss of metal salts in corrosive media, ensures the integrity of the cross-linked network, enables the elastomer to withstand the corrosive environment of chemical pipelines for a long time, reduces the material aging rate, and ensures the long-term stable operation of pipelines. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicating orientation or positional relationships, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] This invention provides a supramolecular polyurethane elastomer, which is prepared from the following raw materials in parts by weight: 100 parts of polyol, 30-50 parts of diisocyanate, 8-15 parts of chain extender, 5-12 parts of 3,4-dihydroxybenzaldehyde ethylenediamine, 3-8 parts of host-guest complex, 2-5 parts of mechanochromic unit, 1-3 parts of metal salt, 0.1-0.5 parts of catalyst, and 50-100 parts of solvent. The chain extender is a furan-maleimide derivative containing Diels-Alder bonds, and its molecular structure contains two hydroxyl terminal groups. The 3,4-dihydroxybenzaldehyde ethylenediamine contains catechol groups and amino groups in its molecular structure. The host-guest complex is composed of α-cyclodextrin and adamantane methanol in a 1:1 molar ratio. The mechanochromic unit is a diol derivative containing azobenzene side groups. Furan-maleimide derivatives containing Diels-Alder bonds can provide reversible covalent crosslinking, which can enhance molecular chain rigidity. The host-guest complex can construct dynamic inter-chain connections, preserving chain segment flexibility. 3,4-Dihydroxybenzaldehyde ethylenediamine and metal salts can form metal coordination bonds, further strengthening the inter-chain bonding force. This allows the elastomer to possess both high tensile strength and high elongation at break. Furthermore, through the reversible covalent crosslinking of Diels-Alder bonds, the dynamic inclusion of the host-guest complex, and the metal coordination bonds, a dense crosslinked network is formed synergistically, which can effectively block Cl. - Corrosion ions penetrate and slow down the degradation rate of molecular chains. At the same time, the catechol groups in 3,4-dihydroxybenzaldehyde ethylenediamine form a stable coordination structure with metal ions, preventing the metal salt from dissociating and being lost in the corrosive medium, ensuring the integrity of the cross-linked network, enabling the elastomer to resist corrosion for a long time and reducing the aging rate.

[0024] In this invention, the preparation method of furan-maleimide derivative containing Diels-Alder bonds is as follows: furan methanol and maleimide are reacted at 80°C for 4-6 hours in a molar ratio of 1.2:1. After purification by column chromatography, furan-maleimide derivative containing Diels-Alder bonds is obtained. The dissociation temperature of its Diels-Alder bonds is 120-140°C. It can quickly dissociate and recombine at high temperatures to supplement repair sites. The host-guest complex is composed of α-cyclodextrin and adamantane methanol in a molar ratio of 1:1. It can achieve self-repair at room temperature through dynamic inclusion between molecular chains. The catechol group in the 3,4-dihydroxybenzaldehyde ethylenediamine molecule forms metal coordination bonds with the metal salt, further strengthening the repair interface and improving repair stability. This ensures that the elastomer can maintain high efficiency self-repair capability in both room temperature and high temperature (such as 120°C) environments.

[0025] In this invention, the azophenyl group in the molecular structure of the diol derivative containing the azophenyl side group is connected to the diol main chain through a spacer group. The spacer group has 2-4 carbon atoms. This spacer group can efficiently transfer the stress generated by mechanical impact and medium pressure during the service of chemical pipelines. When the stress is 5-50 MPa, the azophenyl group will undergo a cis-trans isomerization transition, which manifests as a color change.

[0026] In this invention, the polyol is selected from at least one of polybutylene adipate diol and polytetrahydrofuran ether diol with a number average molecular weight of 2000-4000.

[0027] In this invention, the diisocyanate is selected from at least one of 4,4'-diphenylmethane diisocyanate and hexamethylene diisocyanate.

[0028] In this invention, the metal salt is selected from at least one of ferric chloride and zinc acetate.

[0029] In this invention, the catalyst is dibutyltin dilaurate.

[0030] In this invention, the solvent is selected from at least one of N,N-dimethylformamide and tetrahydrofuran.

[0031] This invention also provides a method for preparing a supramolecular polyurethane elastomer, comprising the following steps: S1: Add the metal salt to the solvent and stir at a rate of 400-600 rpm until completely dissolved to obtain a metal salt solution; S2: The polyol is vacuum dehydrated at 100-120℃ for 2-3 hours, then cooled to 60-70℃ and diisocyanate and catalyst are added. Under nitrogen protection, the mixture is stirred at 300-500 rpm for 1.5-2.5 hours to obtain the prepolymer. S3: Add chain extender, 3,4-dihydroxybenzaldehyde ethylenediamine and metronic color-changing unit sequentially to the prepolymer, heat to 75-85℃, stir at 300-500 rpm for 1-2 h, add host-guest complex, continue stirring at 300-500 rpm for 0.5-1 h, then cool to 40-50℃, add metal salt solution dropwise, and after the addition is complete, keep stirring at 300-500 rpm for 1-1.5 h to obtain reaction solution; S4: Pour the reaction solution into a polytetrafluoroethylene mold, pre-cur at 80°C for 4 hours, and then post-cur at 100°C for 8-12 hours. After demolding, the elastomer is obtained.

[0032] This invention also provides an application of supramolecular polyurethane elastomer in chemical pipelines. For example, it can be used directly in the manufacture of pipeline bodies to replace traditional metal pipelines or ordinary polyurethane pipelines. It can also be used as a pipeline coating, monitoring the integrity of the coating through color changes, repairing minor scratches through self-healing capabilities, and serving as a pipeline repair material to quickly repair local damage at room temperature or high temperature without disassembling the pipeline.

[0033] Example 1 Take 100 parts by weight of polybutylene adipate diol (number average molecular weight 2000), 30 parts of 4,4'-diphenylmethane diisocyanate, 8 parts of furan-maleimide derivative containing Diels-Alder bonds, 5 parts of 3,4-dihydroxybenzaldehyde ethylenediamine, 3 parts of host-guest complex, 2 parts of diol derivative containing azobenzene side groups (spacer group carbon atoms 2), 1 part of ferric chloride, 0.1 part of dibutyltin dilaurate, and 50 parts of N,N-dimethylformamide.

[0034] Ferric chloride was added to N,N-dimethylformamide and stirred at 400 rpm until completely dissolved to obtain a metal salt solution. Polybutylene adipate diol was dehydrated under vacuum at 100°C for 2 hours. After cooling to 60°C, 4,4'-diphenylmethane diisocyanate and dibutyltin dilaurate were added. The mixture was stirred at 300 rpm for 1.5 hours under nitrogen protection to obtain the prepolymer. A furan-maleimide derivative containing a Diels-Alder bond, 3,4-dihydroxybenzaldehyde ethylenediamine, and a diol derivative containing an azobenzene side group were added sequentially to the prepolymer. The mixture was heated to 75°C and stirred at 300 rpm for 1 h. The host-guest complex was then added, and the mixture was stirred at 300 rpm for 0.5 h. The mixture was then cooled to 40°C, and a metal salt solution was added dropwise. After the addition was complete, the mixture was stirred at 300 rpm for 1 h to obtain the reaction solution.

[0035] The reaction solution was poured into a polytetrafluoroethylene mold, pre-cured at 80°C for 4 hours, and then post-cured at 100°C for 8 hours. The elastomer was then demolded.

[0036] Example 2 Take 100 parts by weight of polytetrahydrofuran ether diol (number average molecular weight 3000), 40 parts of hexamethylene diisocyanate, 12 parts of furan-maleimide derivative containing Diels-Alder bonds, 8 parts of 3,4-dihydroxybenzaldehyde ethylenediamine, 5 parts of host-guest complex, 3 parts of diol derivative containing azobenzene side groups (spacer carbon atoms 3), 2 parts of zinc acetate, 0.3 parts of dibutyltin dilaurate, and 75 parts of tetrahydrofuran.

[0037] Zinc acetate was added to tetrahydrofuran and stirred at 500 rpm until completely dissolved to obtain a metal salt solution. Polytetrahydrofuran ether diol was dehydrated under vacuum at 110°C for 2.5 h, cooled to 65°C, and then hexamethylene diisocyanate and dibutyltin dilaurate were added. Under nitrogen protection, the mixture was stirred at 400 rpm for 2 h to obtain the prepolymer. A furan-maleimide derivative containing a Diels-Alder bond, 3,4-dihydroxybenzaldehyde ethylenediamine, and a diol derivative containing an azobenzene side group were added sequentially to the prepolymer. The mixture was heated to 80°C and stirred at 400 rpm for 1.5 h. The host-guest complex was then added, and the mixture was stirred at 400 rpm for 0.8 h. The mixture was then cooled to 45°C, and a metal salt solution was added dropwise. After the addition was complete, the mixture was stirred at 400 rpm for 1.2 h to obtain the reaction solution. The reaction solution was poured into a polytetrafluoroethylene mold, pre-cured at 80°C for 4 hours, and then post-cured at 100°C for 10 hours. The elastomer was then demolded.

[0038] Example 3 Take 100 parts by weight of a mixture of polybutylene adipate diol (number average molecular weight 4000) and polytetrahydrofuran ether diol (number average molecular weight 3500) in a 1:1 ratio; 50 parts by weight of a mixture of 4,4'-diphenylmethane diisocyanate and hexamethylene diisocyanate in a 1:1 ratio; 15 parts by weight of a furan-maleimide derivative containing Diels-Alder bonds; 12 parts by weight of 3,4-dihydroxybenzaldehyde ethylenediamine; 8 parts by weight of a host-guest complex; 5 parts by weight of a diol derivative containing azobenzene side groups (spacer group carbon atoms 4); 3 parts by weight of a mixture of ferric chloride and zinc acetate in a 1:1 ratio; 0.5 parts by weight of dibutyltin dilaurate; and 100 parts by weight of a mixture of N,N-dimethylformamide and tetrahydrofuran in a 1:1 ratio.

[0039] A mixture of ferric chloride and zinc acetate was added to a mixed solvent of N,N-dimethylformamide and tetrahydrofuran, and stirred at 600 rpm until completely dissolved to obtain a metal salt solution. The mixture of polybutylene adipate diol and polytetrahydrofuran ether diol was vacuum dehydrated at 120°C for 3 hours. After cooling to 70°C, a mixture of 4,4'-diphenylmethane diisocyanate and hexamethylene diisocyanate and dibutyltin dilaurate were added. The mixture was stirred at 500 rpm for 2.5 hours under nitrogen protection to obtain the prepolymer. A furan-maleimide derivative containing a Diels-Alder bond, 3,4-dihydroxybenzaldehyde ethylenediamine, and a diol derivative containing an azobenzene side group were sequentially added to the prepolymer. The mixture was heated to 85°C and stirred at 500 rpm for 2 h. The host-guest complex was then added, and the mixture was stirred at 500 rpm for 1 h. The mixture was then cooled to 50°C, and a metal salt solution was added dropwise. After the addition was complete, the mixture was stirred at 500 rpm for 1.5 h to obtain the reaction solution. The reaction solution was poured into a polytetrafluoroethylene mold, pre-cured at 80°C for 4 hours, and then post-cured at 100°C for 12 hours. The elastomer was then demolded.

[0040] Comparative Example 1 Take 100 parts by weight of polybutylene adipate diol (number average molecular weight 2000), 30 parts of 4,4'-diphenylmethane diisocyanate, 8 parts of furan-maleimide derivative containing DA bond, 5 parts of 3,4-dihydroxybenzaldehyde ethylenediamine, 3 parts of host-guest complex, 1 part of ferric chloride, 0.1 parts of dibutyltin dilaurate, and 50 parts of N,N-dimethylformamide.

[0041] Ferric chloride was added to N,N-dimethylformamide and stirred at 400 rpm until completely dissolved to obtain a metal salt solution. Polybutylene adipate diol was dehydrated under vacuum at 100°C for 2 hours. After cooling to 60°C, 4,4'-diphenylmethane diisocyanate and dibutyltin dilaurate were added. The mixture was stirred at 300 rpm for 1.5 hours under nitrogen protection to obtain the prepolymer. A furan-maleimide derivative containing Diels-Alder bonds and 3,4-dihydroxybenzaldehyde ethylenediamine were added sequentially to the prepolymer. The mixture was heated to 75°C and stirred at 300 rpm for 1 h. The host-guest complex was then added, and the mixture was stirred at 300 rpm for 0.5 h. The mixture was then cooled to 40°C, and a metal salt solution was added dropwise. After the addition was complete, the mixture was stirred at 300 rpm for 1 h to obtain the reaction solution. The reaction solution was poured into a polytetrafluoroethylene mold, pre-cured at 80°C for 4 hours, and then post-cured at 100°C for 8 hours. The elastomer was then demolded.

[0042] Comparative Example 2 Take 100 parts by weight of polybutylene adipate diol (number average molecular weight 2000), 30 parts of 4,4'-diphenylmethane diisocyanate, 8 parts of 1,4-butanediol (without Diels-Alder bonds), 5 parts of 3,4-dihydroxybenzaldehyde ethylenediamine, 3 parts of host-guest complex, 2 parts of diol derivative containing azobenzene side groups (spacer group carbon atoms 2), 1 part of ferric chloride, 0.1 part of dibutyltin dilaurate, and 50 parts of N,N-dimethylformamide.

[0043] Ferric chloride was added to N,N-dimethylformamide and stirred at 400 rpm until completely dissolved to obtain a metal salt solution. Polybutylene adipate diol was dehydrated under vacuum at 100°C for 2 hours. After cooling to 60°C, 4,4'-diphenylmethane diisocyanate and dibutyltin dilaurate were added. The mixture was stirred at 300 rpm for 1.5 hours under nitrogen protection to obtain the prepolymer. 1,4-Butanediol, 3,4-dihydroxybenzaldehyde ethylenediamine, and a diol derivative containing an azobenzene side group were added sequentially to the prepolymer. The mixture was heated to 75°C and stirred at 300 rpm for 1 h. The host-guest complex was then added, and the mixture was stirred at 300 rpm for 0.5 h. The mixture was then cooled to 40°C, and a metal salt solution was added dropwise. After the addition was complete, the mixture was stirred at 300 rpm for 1 h to obtain the reaction solution. The reaction solution was poured into a polytetrafluoroethylene mold, pre-cured at 80°C for 4 hours, and then post-cured at 100°C for 8 hours. The elastomer was then demolded.

[0044] Comparative Example 3 Take 100 parts by weight of polybutylene adipate diol (number average molecular weight 2000), 30 parts of 4,4'-diphenylmethane diisocyanate, 8 parts of furan-maleimide derivative containing Diels-Alder bonds, 5 parts of 3,4-dihydroxybenzaldehyde ethylenediamine, 2 parts of diol derivative containing azobenzene side groups (spacer group carbon atoms 2), 1 part of ferric chloride, 0.1 part of dibutyltin dilaurate, and 50 parts of N,N-dimethylformamide.

[0045] Ferric chloride was added to N,N-dimethylformamide and stirred at 400 rpm until completely dissolved to obtain a metal salt solution. Polybutylene adipate diol was dehydrated under vacuum at 100°C for 2 hours. After cooling to 60°C, 4,4'-diphenylmethane diisocyanate and dibutyltin dilaurate were added. The mixture was stirred at 300 rpm for 1.5 hours under nitrogen protection to obtain the prepolymer. A furan-maleimide derivative containing a Diels-Alder bond, 3,4-dihydroxybenzaldehyde ethylenediamine, and a diol derivative containing an azobenzene side group were added sequentially to the prepolymer. The mixture was heated to 75°C, stirred at 300 rpm for 1 h, and then cooled to 40°C. A metal salt solution was added dropwise, and the mixture was stirred at 300 rpm for 1 h after the addition was complete to obtain the reaction solution. The reaction solution was poured into a polytetrafluoroethylene mold, pre-cured at 80°C for 4 hours, and then post-cured at 100°C for 8 hours. The elastomer was then demolded.

[0046] The performance tests of the elastomers prepared in Examples 1-3 and Comparative Examples 1-3 are shown in the table below: Note: Tensile strength and elongation at break tests: A universal testing machine was used for testing. The tensile rate was set to 500 mm / min, and the stress (i.e., tensile strength) and deformation rate (i.e., elongation at break) at the fracture of the elastomer were recorded. Self-healing efficiency test: The elastomer sample was cut into two complete cross-sections and left to heal for 24 hours at room temperature (25℃) and high temperature (120℃) respectively. After the repair was completed, the self-healing efficiency was calculated as (tensile strength after repair / tensile strength before repair) × 100%. Damage warning function test: A gradient stress of 5-50 MPa was applied to the elastomer using a universal testing machine, and the color change of the sample under stress was observed directly with the naked eye. Corrosion resistance test: The elastomer was immersed in a 5% NaCl aqueous solution for 72 hours, and after drying, the tensile strength was tested. The ratio of the tensile strength to the tensile strength before immersion (retention rate) was calculated.

[0047] Because furan-maleimide derivatives containing Diels-Alder bonds can provide reversible covalent crosslinking, they enhance the rigidity of molecular chains. The host-guest complex can construct dynamic connections between molecular chains, preserving the flexibility of chain segments. 3,4-Dihydroxybenzaldehyde ethylenediamine and metal salts (ferric chloride, zinc acetate) can form metal coordination bonds, further strengthening the inter-chain bonding force. This results in tensile strengths of 8.3-9.1 MPa and elongation at break of 590-670% in Examples 1-3. Comparative Example 2 used 1,4-butanediol (without Diels-Alder bonds), which significantly increased the rigidity of the molecular chain and decreased its flexibility, making it unable to effectively disperse external stress. This resulted in a tensile strength of only 7.5-7.8 MPa and an elongation at break of only 520-550%. Comparative Example 3 lacked the host-guest complex, resulting in reduced dynamic connections between molecular chains, lower crosslinking density, and decreased stress transfer efficiency. This led to a decrease in tensile strength to 7.8-8.1 MPa and an elongation at break to 540-570%. In contrast, Comparative Example 1 had a tensile strength of 8.2-8.5 MPa and an elongation at break of 580-620%. This indicates that diol derivatives containing azobenzene side groups have minimal impact on the molecular chain bonding force and flexibility and do not interfere with the mechanical properties of the elastomer.

[0048] At room temperature (25℃), the self-repair efficiency of Examples 1-3 reached 88-93%, while that of Comparative Example 1 was 87-89%. This is because Examples 1-3 and Comparative Example 1 both achieved efficient repair through multiple repair sites including Diels-Alder bonds, host-guest linkages, and metal coordination bonds. Comparative Example 3, lacking a host-guest complex, had fewer repair sites and a self-repair efficiency of 80-83%. Comparative Example 2, lacking Diels-Alder bonds, relied solely on metal coordination bonds for repair, resulting in the fewest repair sites and a self-repair efficiency of only 75-78%. Under high temperature (120℃) conditions, the self-repair efficiency of Examples 1-3 remained at 82-86%, and that of Comparative Example 1 remained at 81-83%. This is because the dissociation temperature of the Diels-Alder bond is 120-140℃. At the test temperature of 120℃, the bond can quickly dissociate and recombine, which can replenish the repair sites. Comparative Example 2 does not contain Diels-Alder bonds. At high temperatures, the metal coordination bonds are easily dissociated, and the static covalent bonds cannot recombine, resulting in a sharp reduction in repair sites and a self-repair efficiency of only 55-58%. Comparative Example 3 lacks a host-guest complex. After the metal coordination bonds dissociate at high temperatures, there are no additional repair sites to replenish the efficiency, and the self-repair efficiency is only 70-73%.

[0049] Examples 1-3 and Comparative Examples 2 and 3 all changed color from pale yellow to orange-red under stress of 5-50 MPa. This is because the azophenyl group in the molecular structure of the diol derivative containing the azophenyl side group is connected to the diol backbone through a spacer group. The spacer group can effectively transfer stress, causing the azophenyl group to undergo cis-trans isomerization, which is manifested as the color changing from pale yellow to orange-red. This can be used to monitor hidden micro-damage to pipelines caused by stress in real time. Comparative Example 1, lacking the diol derivative containing the azophenyl side group, cannot undergo cis-trans isomerization and therefore shows no color change under stress.

[0050] The tensile strength retention rates of Examples 1-3 reached 86-90%, and that of Comparative Example 1 reached 85-87%. This is because the furan-maleimide derivative containing Diels-Alder bonds provides reversible covalent crosslinking, and the host-guest complex constructs dynamic inter-chain connections. The metal salt forms metal coordination bonds with 3,4-dihydroxybenzaldehyde ethylenediamine, and the three work together to form a dense crosslinked network that can effectively block Cl. - This allows for penetration, slowing down the degradation rate of the molecular chain. Simultaneously, the catechol groups in 3,4-dihydroxybenzaldehyde ethylenediamine can react with metal ions (Fe...). 3+ Zn 2+ This forms a stable coordination structure, preventing the metal salt from dissociating and leaching in the corrosive medium, thus further improving corrosion resistance. Comparative Example 2 lacks Diels-Alder bonds, resulting in insufficient density of the cross-linked network. - It is easily penetrated, and the retention rate drops to 80-82%. Comparative Example 3 lacks the host-guest complex, and its cross-linking network is the most loose. -It has the fastest penetration rate, but the molecular chain degradation is more severe, and the retention rate is only 78-80%.

[0051] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications and equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A supramolecular polyurethane elastomer, characterized in that, The elastomer is prepared from the following raw materials in parts by weight: 100 parts of polyol, 30-50 parts of diisocyanate, 8-15 parts of chain extender, 5-12 parts of 3,4-dihydroxybenzaldehyde ethylenediamine, 3-8 parts of host-guest complex, 2-5 parts of metronidazole unit, 1-3 parts of metal salt, 0.1-0.5 parts of catalyst, and 50-100 parts of solvent; The chain extender is a furan-maleimide derivative containing Diels-Alder bonds, and its molecular structure contains two hydroxyl terminal groups; The molecular structure of the 3,4-dihydroxybenzaldehyde ethylenediamine contains catechol groups and amino groups; The host-guest complex is composed of α-cyclodextrin and adamantane methanol in a 1:1 molar ratio. The mechanochromic unit is a diol derivative containing an azobenzene side group.

2. The elastomer according to claim 1, characterized in that, The preparation method of the furan-maleimide derivative containing Diels-Alder bonds is as follows: furanol and maleimide are reacted at 80℃ for 4-6 h at a molar ratio of 1.2:1, and the furan-maleimide derivative containing Diels-Alder bonds is obtained after purification by column chromatography. The dissociation temperature of the Diels-Alder bonds is 120-140℃.

3. The elastomer according to claim 1, characterized in that, The azophenyl group in the molecular structure of the diol derivative containing the azophenyl side group is connected to the diol backbone through a spacer group. The spacer group has 2-4 carbon atoms and can undergo cis-trans isomerization under stress of 5-50 MPa, resulting in a color change.

4. The elastomer according to claim 1, characterized in that, The polyol is selected from at least one of polybutylene adipate diol and polytetrahydrofuran ether diol with a number average molecular weight of 2000-4000.

5. The elastomer according to claim 1, characterized in that, The diisocyanate is selected from at least one of 4,4'-diphenylmethane diisocyanate and hexamethylene diisocyanate.

6. The elastomer according to claim 1, characterized in that, The metal salt is selected from at least one of ferric chloride and zinc acetate.

7. The elastomer according to claim 1, characterized in that, The catalyst is dibutyltin dilaurate.

8. The elastomer according to claim 1, characterized in that, The solvent is selected from at least one of N,N-dimethylformamide and tetrahydrofuran.

9. A method for preparing a supramolecular polyurethane elastomer, characterized in that, Includes the following steps: S1: Add the metal salt to the solvent and stir at a rate of 400-600 rpm until completely dissolved to obtain a metal salt solution; S2: The polyol is vacuum dehydrated at 100-120℃ for 2-3 hours, then cooled to 60-70℃ and diisocyanate and catalyst are added. Under nitrogen protection, the mixture is stirred at 300-500 rpm for 1.5-2.5 hours to obtain the prepolymer. S3: Add chain extender, 3,4-dihydroxybenzaldehyde ethylenediamine and metronic color-changing unit sequentially to the prepolymer, heat to 75-85℃, stir at 300-500 rpm for 1-2 h, add host-guest complex, continue stirring at 300-500 rpm for 0.5-1 h, then cool to 40-50℃, add metal salt solution dropwise, and after the addition is complete, keep stirring at 300-500 rpm for 1-1.5 h to obtain reaction solution; S4: Pour the reaction solution into a polytetrafluoroethylene mold, pre-cur at 80°C for 4 hours, and then post-cur at 100°C for 8-12 hours. After demolding, the elastomer is obtained.

10. An application of a supramolecular polyurethane elastomer, characterized in that, Used in chemical pipelines.

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