A high-recovery self-healing polyurethane elastomer material and a method for preparing the same

Abstract

The application belongs to the field of novel functional materials, and particularly relates to a high-recovery self-healing polyurethane elastomer material and a preparation method thereof. The self-healing elastomer material is prepared from the following components: 50-100 parts by weight of a polyurethane prepolymer, and 13-28 parts by weight of a chain extender composition. The polyurethane prepolymer is obtained from a polyol with a molecular weight of 2000 and isophorone diisocyanate under catalytic reaction of dibutyltin dilaurate. The chain extender is a combination of a pendant chain chain extender, 4,4'-diamino diphenyl disulfide and 4,4'-diamino diphenyl ethane. The solvent is N,N-dimethylacetamide. The polyurethane elastomer provided by the application has a self-healing performance recovery rate of more than 90% at 60 DEG C for 12 hours, is suitable for precision instrument laboratory floor coating, medical materials and aerospace fields, realizes scratch self-repairing, and prolongs the service life.

Description

Technical Field

[0001] This invention belongs to the field of novel functional materials, and in particular relates to a high-recovery-rate self-healing polyurethane elastomer material and its preparation method. Background Technology

[0002] In applications such as aerospace and precision instruments, the environmental temperature is complex and variable. Fatigue damage and microcracks are inevitable in materials subjected to frequent impacts and noise absorption, which severely impacts the precision and lifespan of mechanical equipment. As a commonly used material, endowing polyurethane elastomer coatings with self-healing capabilities, enabling damage self-repair, can provide materials with more durable high performance and a longer service life.

[0003] CN115850952A discloses a polyurethane elastomer that utilizes molecular fluidity and reversible dynamic reactions of disulfide bonds to control "microphase separation" to adjust the degree of separation between soft and hard segments, further balancing the material's mechanical properties and self-healing ability to obtain a self-healing polyurethane with high mechanical properties. However, the polyurethane elastomer provided is a cured material with very low molecular fluidity, insufficient for flow and healing at the cut.

[0004] CN115785386A discloses a method of introducing hydroxylated vegetable oil-based monomers into a polyurethane network, giving it a long alkane backbone structure and abundant hydrogen bonding sites. Under the synergistic effect of dehydration and hierarchical hydrogen bonding, the polyurethane elastomer exhibits excellent self-healing properties at room temperature. However, according to the embodiments described in this application, its healing efficiency is between 40-70%, which is difficult to meet the requirements of high self-healing recovery rates in fields such as surface protective coatings, medical materials, and aerospace, thus limiting the application of self-healing materials.

[0005] Therefore, developing a viscoelastic polymer material with high recovery rate and self-healing properties has positive economic and social significance. Summary of the Invention

[0006] This invention addresses the numerous shortcomings of existing technologies by providing a high-recovery-rate self-healing polyurethane elastomer material and its preparation method. The self-healing elastomer material is prepared from the following components: 50-100 parts by weight of polyurethane prepolymer and 13-28 parts by weight of a chain extender composition. The polyurethane prepolymer is obtained by reacting a polyol with a molecular weight of 2000 and isophorone diisocyanate under the catalysis of dibutyltin dilaurate. The chain extender is a combination of a suspended chain extender, 4,4'-diaminodiphenyl disulfide, and 4,4'-diaminodiphenyl ethane, with N,N-dimethylacetamide as the solvent. The self-healing polyurethane elastomer is obtained by first synthesizing the prepolymer, then pre-chain extending, followed by vigorous stirring, vacuum degassing, and post-curing with the chain extender composition. The polyurethane elastomer of this invention exhibits a self-healing performance recovery rate of over 90% after 12 hours at 60°C, making it suitable for applications such as precision instrument laboratory floor coatings, medical materials, and aerospace, achieving scratch self-repair and extending service life.

[0007] Prior to this invention, the applicant filed a patent application on January 6, 2023, entitled "A Binary Hydroxyl-Terminated Chain Extender with Controllable Molecular Weight of Hanging Chain and Its Application," publication number CN 115975175 A, publication date April 18, 2023. This patent application provided a chain extender and demonstrated its application in the preparation of polyurethane microporous elastomers. Through further research, the applicant discovered that the aforementioned chain extender exhibits unexpected effects when used in the preparation of high-recovery-rate self-healing polyurethane elastomer materials, ultimately leading to the technical solution of this application as follows:

[0008] The applicant first provided the suspended chain extender used, which is the chain extender disclosed in CN 115975175 A. A more preferred chain extender composition and preparation method are as follows:

[0009] The components of the suspended chain extender are as follows, by weight:

[0010]

[0011] The synthesis steps are as follows:

[0012] (1) Add polyethylene glycol monomethyl ether 550 to a three-necked flask, heat to 110°C and evacuate to -0.096MPa, stir for 2 hours to remove water and other small molecule substances, then purge with nitrogen to release pressure and keep for use.

[0013] (2) After repeatedly purging the three-necked flask with nitrogen, add isoflurane diisocyanate, acetone and dibutyltin dilaurate and heat to 60°C. At 500 rpm and 60°C, slowly add polyethylene glycol monomethyl ether 550 treated in the above synthesis step (1) at a drip rate of 0.5-2 mL / min using a micro-peristaltic injection pump. Add it in equimolar amounts and react for 6 h. Then raise the temperature to 80°C and continue the reaction for 2 h to obtain the intermediate product.

[0014] (3) After repeatedly purging the three-necked flask with nitrogen and baking it, add sublimated and purified 2-amino-1,3-propanediol and acetone. After the solid particles are fully dissolved, heat the system to 35°C and slowly add an equimolar amount of intermediate product dropwise at a rate of 0.5-2 mL / min using a micro-peristaltic syringe pump. React for 6 hours. Remove the solvent by rotary evaporation, place the flask in a vacuum oven at 50°C for 7 days, and then use it to finally obtain the suspended chain extender.

[0015] After obtaining the above-mentioned chain extender, the more specific technical solution of this application is as follows:

[0016] A high-recovery-rate self-healing polyurethane elastomer material, comprising, by weight, 63-100 parts of polyurethane prepolymer and 13-28 parts of chain extender composition.

[0017] The polyurethane prepolymer is obtained by reacting a polyol with a molecular weight of 2000 and isophorone diisocyanate under the catalysis of dibutyltin dilaurate, wherein the mass ratio of polyol:isophorone diisocyanate:dibutyltin dilaurate is 50-100:13-28:0.1-0.2.

[0018] Polyols with a molecular weight of 2000 can significantly improve material properties. The final elastomer material synthesized in the above proportion has self-healing properties, mechanical properties and damping properties; specifically, it can be selected from polytetrahydrofuran ether diol or polycaprolactone diol.

[0019] The chain extender composition is a combination of the suspended chain extender prepared above, 4,4'-diaminodiphenyl disulfide, and 4,4'-diaminodiphenyl ethane, with a molar ratio of 30:30-50:20-60.

[0020] This invention overcomes the deficiency of single-product self-healing processes that cannot achieve high recovery rates by introducing suspended chains and dynamic disulfide bonds. The dynamic disulfide bonds are provided by 4,4'-diaminodiphenyl disulfide. The combined use of 4,4'-diaminodiphenyl ethane and 4,4'-diaminodiphenyl disulfide not only introduces dynamic disulfide bonds into the system but also leverages the high bond energy of 4,4'-diaminodiphenyl ethane to improve the tensile strength of the material. The suspended chains are provided by a synthesized suspended chain extender. Hydrogen bonding is one of the main factors affecting the self-healing recovery rate. The ester groups of the selected polycaprolactone diol have strong polarity, which can significantly improve the hydrogen bonding and mechanical properties of the material. The suspended chains contain many polar groups, and the exchange of dynamic disulfide bonds can drive chain segment slippage, making it easier for polar groups to approach each other. The addition of both further enhances the hydrogen bonding within the system. Secondly, the introduced suspension chains possess multiple relaxation motion modes, which can disrupt the crystallinity of the system and enhance the mobility of chain segments. This results in more chain entanglement at the healing site, promoting wound healing. The exchange frequency of disulfide bonds increases with increasing temperature. As the disulfide bond content in the system increases, the content of dynamically exchanged disulfide bonds also increases. The exchange of disulfide bonds drives the migration of chain segments within the system. This effect is more significant at 60℃, which is beneficial for promoting wound healing. Tests show that the self-healing performance recovery rate can reach over 90% after 12 hours at 60℃.

[0021] The high-recovery-rate self-healing polyurethane elastomer material prepared using the above-mentioned raw materials leverages the designability of the polyurethane network structure and the reversible dynamic exchange of dynamic disulfide bonds to achieve a synergistic effect when used together. The introduction of both dangling chains and dynamic disulfide bonds reduces the degree of microphase separation in the material. The self-healing ability of the material is significantly enhanced due to the synergistic effect of these two components. When the amount of 4,4'-diaminodiphenyl disulfide is not less than 30%, the self-healing rate can reach over 91%.

[0022] In addition, this invention also provides a method for preparing a high-recovery-rate self-healing polyurethane elastomer material, the specific steps of which are as follows:

[0023] (1) Preparation of polyurethane prepolymer: Add the amount of dehydrated polyol (molecular weight 2000) to a three-necked flask, add the amount of isophorone diisocyanate under nitrogen protection, stir and react at 80°C for 2 hours, then add the amount of dibutyltin dilaurate, and continue to react for 2 hours to obtain a transparent prepolymer.

[0024] (2) Preparation of polyurethane elastomer: Under nitrogen protection, the temperature of the transparent prepolymer obtained in step (1) was lowered to 70°C. The amount of suspension chain extender, 4,4'-diaminodiphenyl disulfide and 1,4-butanediol were fully dissolved in N,N-dimethylacetamide solvent (the amount of solvent was 3 to 6 times the total mass of suspension chain extender and 4,4'-diaminodiphenyl disulfide). The solvent was added to the transparent prepolymer and the reaction was continued for 5 hours to obtain a light yellow transparent prepolymer with suspension chains and disulfide bonds in the main chain.

[0025] The system temperature was lowered to room temperature, and a measured amount of 4,4'-diaminodiphenyl ethane was added to initiate the reaction. N,N-dimethylacetamide was added to adjust the viscosity of the system, ensuring that the product viscosity was sufficient to flow smoothly and fill the mold within 30 seconds. After the system was rapidly stirred for 5 minutes to ensure thorough mixing, it was quickly poured into a polytetrafluoroethylene mold to allow it to flow smoothly. The sample was placed in a vacuum oven and defoamed at -0.096 MPa for 0.5 hours. Then, the ambient temperature was raised to 70°C and the reaction was carried out under a negative pressure of -0.096 MPa for 24 hours. Finally, the sample was transferred to a 70°C forced-air oven and reacted for 12 hours to obtain the polyurethane elastomer.

[0026] The elastomer material obtained by this method exhibits good processing fluidity, sufficient chain extension reaction time, more complete chain extension reaction, more regular and uniform molecular chains, and more stable performance in all regions of the material sample. The solvent N,N-dimethylacetamide can be completely removed under continuous heating and negative pressure, leaving no residue in the final product.

[0027] In summary, the high-recovery-rate self-healing polyurethane elastomer material provided by this invention features rapid low-temperature recovery and a high self-healing rate. In particular, when the amount of dynamic disulfide bond compound exceeds 30%, the self-healing rate can exceed 90%, which greatly improves the lifespan and self-repairability of the ground coating in harsh environments. Attached Figure Description

[0028] Figure 1 These are stereomicroscopic images of self-healing before and after Comparative Example 1.

[0029] Figure 2 These are stereomicroscopic images of self-healing before and after in Example 3. Detailed Implementation

[0030] The invention will be further illustrated below with specific implementation examples. These examples are only intended to provide a complete and clear explanation of the invention, and are not intended to represent all possible implementations. All other implementations created based on this invention are within the scope of protection of this invention. Unless otherwise specified, conventional techniques are used in the following embodiments.

[0031] Example 1

[0032] Preparation of a suspended chain extender, wherein the components are as follows (parts by weight):

[0033]

[0034] The synthesis steps are as follows:

[0035] (1) Add polyethylene glycol monomethyl ether 550 to a three-necked flask, heat to 110°C and evacuate to -0.096MPa, stir for 2 hours to remove water and other small molecule substances, then purge with nitrogen to release pressure and keep for use.

[0036] (2) After repeatedly purging the three-necked flask with nitrogen, add isoflurane diisocyanate, acetone and dibutyltin dilaurate and heat to 60°C. At 500 rpm and 60°C, slowly add polyethylene glycol monomethyl ether 550 treated in the above synthesis step (1) at a drip rate of 0.5-2 mL / min using a micro-peristaltic injection pump. Add it in equimolar amounts and react for 6 h. Then raise the temperature to 80°C and continue the reaction for 2 h to obtain the intermediate product.

[0037] (3) After repeatedly purging the three-necked flask with nitrogen and baking it, sublimated and purified 2-amino-1,3-propanediol and acetone were added. After the solid particles were fully dissolved, the system was heated to 35°C. An equimolar amount of intermediate product was slowly added dropwise using a micro-peristaltic syringe pump at a dropping rate of 0.5-2 mL / min. The reaction was allowed to proceed for 6 hours. The solvent was removed by rotary evaporator, and the mixture was placed in a vacuum oven at 50°C for 7 days before use. The resulting suspended chain extender (molecular weight 863.4) was finally obtained. The suspended chain extenders prepared in this example were used in the following examples and comparative examples.

[0038] Example 2

[0039] A high-recovery-rate self-healing polyurethane elastomer material and its preparation method, wherein the components are as follows (parts by weight):

[0040]

[0041] The synthesis steps are as follows:

[0042] (1) Preparation of polyurethane prepolymers containing dangling chains and dynamic disulfide bonds

[0043] Dehydrated polytetrahydrofuran ether diol 2000 (molecular weight 2000) was added to a three-necked flask, and isophorone diisocyanate was added under nitrogen protection. The mixture was stirred at 80°C for 2 hours. Then, dibutyltin dilaurate was added, and the reaction was continued for 2 hours to obtain a transparent prepolymer.

[0044] Under nitrogen protection, the temperature of the transparent prepolymer obtained above was lowered to 70°C. A certain amount of dangling chain extender and 4,4'-diaminodiphenyl disulfide were fully dissolved in N,N-dimethylacetamide solvent and added to the transparent prepolymer. The reaction was continued for 5 hours to obtain a pale yellow transparent prepolymer with dangling chains and disulfide bonds in the main chain.

[0045] (2) Preparation of polyurethane elastomers

[0046] The system temperature was lowered to room temperature, and a measured amount of 4,4'-diaminodiphenyl ethane was added to initiate the reaction. N,N-dimethylacetamide was then added to adjust the system viscosity (the product viscosity should ensure it flows smoothly and fills the mold within 30 seconds). After rapid stirring for 5 minutes to ensure thorough mixing, the mixture was quickly poured into a polytetrafluoroethylene mold to allow it to flow smoothly. The sample was placed in a vacuum oven and defoamed at -0.096 MPa for 0.5 hours. The ambient temperature was then raised to 70°C and the reaction was continued under a negative pressure of -0.096 MPa for 24 hours. Finally, the sample was transferred to a 70°C forced-air oven and reacted for 12 hours. The dangling chain extender accounted for 30% of the total chain extender molar amount, and 4,4'-diaminodiphenyl disulfide accounted for 50% of the total chain extender molar amount, ultimately yielding a polyurethane elastomer containing dangling chains and dynamic disulfide bonds.

[0047] Example 3

[0048] A high-recovery-rate self-healing polyurethane elastomer material and its preparation method, wherein the components are as follows (parts by weight):

[0049]

[0050] Synthesis steps: Follow steps (1) and (2) in Example 2, with only the following adjustments: replace polytetrahydrofuran ether diol 2000 with polycaprolactone diol 2000, keep the mass fractions of each component unchanged, and use the same amounts as above. All other specific operating steps are the same as in Example 2. The molar amount of the dangling chain extender accounts for 30% of the total molar amount of the chain extender system, and the molar amount of 4,4'-diaminodiphenyl disulfide accounts for 50% of the total molar amount of the chain extender system. Finally, a polyurethane elastomer with a different main chain structure containing dangling chains and dynamic disulfide bonds is obtained.

[0051] Comparative Example 1

[0052] A high-recovery-rate self-healing polyurethane elastomer material and its preparation method, wherein the components are as follows (parts by weight):

[0053]

[0054] The synthesis steps are as follows: follow steps (1) and (2) in Example 2, with only the following adjustments required: replace polytetrahydrofuran ether diol 2000 with polycaprolactone diol 2000, replace the chain extender of the synthetic suspension chain with 1,4-butanediol with a straight chain structure, and replace 4,4'-diaminodiphenyl ethane with carbon-carbon bonds in the middle of the molecule as a control experiment.

[0055] In synthesis step (1), the dangling chain extender and 4,4'-diaminodiphenyl disulfide were replaced with equimolar amounts of 1,4-butanediol and 4,4'-diaminodiphenyl ethane. The remaining 4,4'-diaminodiphenyl ethane (1.39 parts, consistent with the amount added during the final chain extension in Example 2) was used for the final chain extension reaction, and the amounts of other components were adjusted as described above. All other specific operating steps were the same as those in Example 2, ultimately yielding a polyurethane elastomer free of dangling chains and dynamic disulfide bonds.

[0056] Depend on Figure 2 It can be seen that the scratches on the material obtained in Example 3 have almost disappeared after self-healing, compared to... Figure 1 In the comparative example, the unmodified polyurethane elastomer material still showed obvious damage after self-healing, indicating poor self-healing performance and a significant difference compared to the modified material. This demonstrates that the addition of dangling chains and disulfide bonds both contribute to the self-healing function of the material. Firstly, hydrogen bonding is one of the main factors affecting the repair rate of self-healing samples; the addition of both enhances hydrogen bonding within the system, promoting self-healing. Secondly, the introduced dangling chains possess multiple relaxation motion modes, which can disrupt the crystallinity of the system and enhance chain segment mobility. This allows for more chain entanglement at the healing site, promoting wound healing. Furthermore, the exchange frequency of disulfide bonds increases with temperature. As the disulfide bond content in the system increases, the amount of disulfide bonds participating in dynamic exchange also increases. The exchange of disulfide bonds drives the migration of chain segments within the system, and this effect is more pronounced at 60℃, which is beneficial for promoting the repair of the material's fracture surface. Therefore, the self-healing effect of the sample modified by the combined use of dangling chains and disulfide bonds is significantly improved. When the amount of 4,4'-diaminodiphenyl disulfide is 50% of the total molar amount of chain extender, the self-healing rate is increased to 95%.

[0057] Comparative Example 2

[0058] A high-recovery-rate self-healing polyurethane elastomer material and its preparation method, wherein the components are as follows (parts by weight):

[0059]

[0060] The experimental steps are as follows:

[0061] The synthesis steps are as follows: Follow steps (1) and (2) in Example 2, with only the following adjustments: Polytetrahydrofuran ether diol 2000 is replaced with polycaprolactone diol 2000, and 1,4-butanediol with a straight chain structure is used instead of the suspension chain extender for control experiments. The suspension chain extender in synthesis step (1) is replaced with an equimolar amount of 1,4-butanediol, and the amounts of other components are adjusted as above. All other specific operating steps are the same as in Example 2. The molar amount of 4,4'-diaminodiphenyl disulfide accounts for 30% of the total chain extender system molar amount, ultimately obtaining a polyurethane elastomer with a main chain structure containing dynamic disulfide bonds.

[0062] Comparative Example 3

[0063] A high-recovery-rate self-healing polyurethane elastomer material and its preparation method, wherein the components are as follows (parts by weight):

[0064]

[0065] The synthesis steps are as follows: Steps (1) and (2) in Example 2 are followed, with only the following adjustments: Polytetrahydrofuran ether diol 2000 is replaced with polycaprolactone diol 2000, and 4,4'-diaminodiphenyl ethane containing carbon-carbon bonds in the middle of the molecule is used instead of 4,4'-diaminodiphenyl disulfide as a control. In synthesis step (1), 4,4'-diaminodiphenyl disulfide is replaced with an equimolar amount of 4,4'-diaminodiphenyl ethane, and the amounts of other components are adjusted as described above. All other specific operational steps are the same as in steps (1) and (2) of Example 2, wherein the molar amount of the suspended chain extender accounts for 30% of the total molar amount of the chain extender system, ultimately obtaining a polyurethane elastomer with a main chain structure containing suspended chains.

[0066] Comparative Example 4

[0067] A high-recovery-rate self-healing polyurethane elastomer material and its preparation method, wherein the components are as follows (parts by weight):

[0068]

[0069] The experimental steps are as follows:

[0070] The synthesis steps are as follows: Follow steps (1) and (2) in Example 2, with only the following adjustments required. Polytetrahydrofuran ether diol 2000 is replaced with polycaprolactone diol 2000, and the amount of 4,4'-diaminodiphenyl disulfide is adjusted to 10% of the total molar amount of the chain extender system. The amounts of other components are adjusted as described above. All other specific operational steps are the same as in Example 2, except that the molar amount of the suspended chain extender accounts for 30% of the total molar amount of the chain extender system, and the molar amount of 4,4'-diaminodiphenyl disulfide accounts for 10% of the total molar amount of the chain extender system. Finally, a polyurethane elastomer with a main chain structure containing suspended chains and dynamic disulfide bonds is obtained.

[0071] Comparative Example 5

[0072] A high-recovery-rate self-healing polyurethane elastomer material and its preparation method, wherein the components are as follows (parts by weight):

[0073]

[0074]

[0075] The experimental steps are as follows:

[0076] The synthesis steps are as follows: Follow steps (1) and (2) in Example 2, with only the following adjustments required. Polytetrahydrofuran ether diol 2000 is replaced with polycaprolactone diol 2000, and the amount of 4,4'-diaminodiphenyl disulfide is adjusted to 30% of the total molar amount of the chain extender system. The amounts of other components are adjusted as described above. All other specific operational steps are the same as in Example 2, except that the molar amount of the suspended chain extender accounts for 30% of the total molar amount of the chain extender system, and the molar amount of 4,4'-diaminodiphenyl disulfide accounts for 30% of the total molar amount of the chain extender system. Finally, a polyurethane elastomer with a main chain structure containing suspended chains and dynamic disulfide bonds is obtained.

[0077] Experimental Example

[0078] The above materials were subjected to various performance tests after being placed at room temperature for 7 days. The tensile strength of the polyurethane elastomer was tested on a GT-TCS-2000 universal testing machine manufactured by Taiwan High Technology Testing Instruments Co., Ltd. A type II dumbbell cutter was used to cut the specimens into dumbbell shapes. The tensile speed was 100 mm / min, according to GB / T528-2009 standard. The self-healing performance test involved cutting a standard type II dumbbell-shaped specimen in half, completely joining the two fractured sections together, and placing it in a 60℃ environment for 12 hours for healing. After cooling to room temperature, the mechanical properties of the specimens were tested according to GB / T528-2009 standard at a tensile speed of 100 mm / min. Five parallel tests were conducted for each material, and the average value was taken. The self-healing efficiency was defined as the ratio of the tensile strength of the healed sample to the tensile strength of the original sample.

[0079] The mechanical properties of the polyurethane elastomer materials prepared in Examples 2 and 3, as well as Comparative Examples 1-5, and commercially available products (polyurethane elastomer materials manufactured by BASF) before and after self-healing were tested, and the results are as follows:

[0080]

[0081] By comparing the performance with the control samples, it can be seen that: Comparative Example 1 is a blank control example without the use of suspended chain extender and 4,4'-diaminodiphenyl disulfide; Comparative Examples 2 and 3 are examples using 30% 4,4'-diaminodiphenyl disulfide or 30% suspended chain extender, respectively; Comparative Example 4 is an example using 30% suspended chain extender and 10% 4,4'-diaminodiphenyl disulfide; and Comparative Example 5 is an example using 30% suspended chain extender and 30% 4,4'-diaminodiphenyl disulfide. The percentage content of the chain extender used above is a percentage of the total molar amount of the chain extender system. The comparative examples sufficiently demonstrate that without using both chain extenders (suspended chain extender and 4,4'-diaminodiphenyl disulfide), using only one chain extender (suspended chain extender or 4,4'-diaminodiphenyl disulfide), and using insufficient amounts of chain extender (4,4'-diaminodiphenyl disulfide), the beneficial self-healing effect of 90% cannot be achieved, and a high recovery rate cannot be realized. The self-healing characteristics of the polyurethane elastomers obtained in Examples 2 and 3 are characterized by a high self-healing recovery rate, reaching 91% and 95% respectively after 12 hours at 60°C. The branching effect of the suspended chains reduces the crystallinity of the system, and the disulfide bond energy is relatively weak, which slightly reduces the tensile strength of the corresponding materials. However, the polar groups of the suspended chains, the various relaxation behaviors of the chain segments, and the reversible exchange of dynamic disulfide bonds are very beneficial to improving the self-healing performance of the materials. When the self-healing efficiency of the materials reaches over 90%, they still have a tensile strength close to 6 MPa, which can meet the strength requirements of ground coating materials while giving the materials excellent self-healing properties. This product offers better repairability and lifespan for ground coatings, showing promising application prospects. Before use, solvents in the system can be thoroughly removed through negative pressure heating purification. Following chain extension, the material is manually pressed and bonded to the substrate using a flat plate, ensuring complete adhesion without noticeable air bubbles. As the chain extension reaction proceeds, the material gradually solidifies, ultimately yielding a coating material with high self-healing properties.

[0082] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The description of the above embodiments can help understand the principles and methods of the present invention. However, the above embodiments are not unique and should not be construed as limiting the present invention. At the same time, those skilled in the art can make flexible changes to the specific implementation methods and application scope based on the principles and methods of the present invention.

Claims

1. A high-recovery-rate self-healing polyurethane elastomer material, characterized in that, Its composition, by weight, includes: 63-100 parts of polyurethane prepolymer and 13-28 parts of chain extender composition; The polyurethane prepolymer is obtained by reacting a polyol with a molecular weight of 2000 and isophorone diisocyanate under the catalysis of dibutyltin dilaurate, wherein the mass ratio of polyol:isophorone diisocyanate:dibutyltin dilaurate is 50-100:13-28:0.1-0.

2. The chain extender composition is a combination of a suspended chain extender, 4,4'-diaminodiphenyl disulfide, and 4,4'-diaminodiphenyl ethane, in a molar ratio of 30:30-50:20-60. The suspended chain extender comprises the following components in parts by weight: Polyethylene glycol monomethyl ether 550 100 parts, 40 parts of isoflurane diisocyanate 17 parts of 2-amino-1,3-propanediol 0.1 parts of dibutyltin dilaurate, 20 parts acetone; The specific steps of the polyurethane elastomer material preparation method are as follows: (1) Preparation of polyurethane prepolymer: Dehydrated polyol was added to a three-necked flask, and isophorone diisocyanate was added under nitrogen protection. The mixture was stirred and reacted at 80°C for 2 hours. Then dibutyltin dilaurate was added and the reaction was continued for 2 hours to obtain a transparent prepolymer. (2) Preparation of polyurethane elastomer: Under nitrogen protection, the temperature of the transparent prepolymer obtained in step (1) was lowered to 70°C. The suspension chain extender and 4,4'-diaminodiphenyl disulfide were fully dissolved in N,N-dimethylacetamide solvent and added to the above transparent prepolymer. The mixture was stirred and reacted for 5 h to obtain a light yellow transparent prepolymer with suspension chains and disulfide bonds in the main chain. The system temperature was lowered to room temperature, and 4,4'-diaminodiphenyl ethane was added to react. N,N-dimethylacetamide was added to adjust the viscosity of the system to ensure that the viscosity of the product was leveled and filled the mold within 30 s. The system was stirred rapidly for 5 min to mix thoroughly and then quickly poured into a polytetrafluoroethylene mold to make it flow smoothly. The sample was placed in a vacuum oven and defoamed at -0.096 MPa for 0.5 h. Then the ambient temperature was raised to 70 ℃ and the reaction was carried out under negative pressure of -0.096 MPa for 24 h. Finally, it was transferred to a 70 ℃ forced-air oven for 12 h of reaction. h yields polyurethane elastomer.

2. The high-recovery-rate self-healing polyurethane elastomer material according to claim 1, characterized in that, The synthesis steps of the suspended chain extender are as follows: (1) Add polyethylene glycol monomethyl ether 550 to a three-necked flask, heat to 110 °C and evacuate to -0.096 MPa, stir for 2 h to remove water, and then purge with nitrogen to release pressure for later use; (2) After repeatedly purging the three-necked flask with nitrogen, add isoflurane diisocyanate, acetone and dibutyltin dilaurate and heat to 60 °C. At 500 rpm and 60 °C, slowly add polyethylene glycol monomethyl ether 550 treated in the above synthesis step (1) by a micro-peristaltic injection pump at a rate of 0.5-2 mL / min. Add it in equal molar amounts and react for 6 h. Then raise the temperature to 80 °C and continue the reaction for 2 h to obtain the intermediate product. (3) After repeatedly purging the three-necked flask with nitrogen and baking it, add sublimated and purified 2-amino-1,3-propanediol and acetone. After the solid particles are fully dissolved, heat the system to 35 °C and slowly add an equimolar amount of intermediate product to it with a micro-peristaltic injection pump at a dropping rate of 0.5-2 mL / min. React for 6 h. Remove the solvent by rotary evaporation, place it in a vacuum oven at 50 °C for 7 days before use, and finally obtain the suspended chain extender.

3. A method for preparing the high-recovery-rate self-healing polyurethane elastomer material according to claim 1, characterized in that, The specific steps are as follows: (1) Preparation of polyurethane prepolymer: Dehydrated polyol was added to a three-necked flask, and isophorone diisocyanate was added under nitrogen protection. The mixture was stirred and reacted at 80 °C for 2 h. Then dibutyltin dilaurate was added and the reaction was continued for 2 h to obtain a transparent prepolymer. (2) Preparation of polyurethane elastomer: Under nitrogen protection, the temperature of the transparent prepolymer obtained in step (1) was lowered to 70 °C. The suspension chain extender and 4,4'-diaminodiphenyl disulfide were fully dissolved in N,N-dimethylacetamide solvent and added to the above transparent prepolymer. The mixture was stirred and reacted for 5 h to obtain a light yellow transparent prepolymer with suspension chains and disulfide bonds in the main chain. The system temperature was lowered to room temperature, and 4,4'-diaminodiphenyl ethane was added to react. N,N-dimethylacetamide was added to adjust the viscosity of the system to ensure that the viscosity of the product was leveled and filled the mold within 30 s. The system was stirred rapidly for 5 min to mix thoroughly and then quickly poured into a polytetrafluoroethylene mold to make it flow smoothly. The sample was placed in a vacuum oven and defoamed at -0.096 MPa for 0.5 h. Then the ambient temperature was raised to 70 °C and the reaction was carried out under negative pressure of -0.096 MPa for 24 h. Finally, it was transferred to a 70 °C forced-air oven for 12 h of reaction. h yields polyurethane elastomer.

4. The method for preparing the high-recovery-rate self-healing polyurethane elastomer material according to claim 3, characterized in that, In step (2), the amount of N,N-dimethylacetamide solvent used is 3-6 times the total mass of the suspension chain extender and 4,4'-diaminodiphenyl disulfide.

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