A polyurethane elastomer, its preparation and use

Abstract

The present application relates to a kind of polyurethane elastomer and its preparation method and application.The raw materials of the polyurethane elastomer include the following components: polytetramethylene ether glycol, polyisocyanate, oxime chain extender and hydrazide chain extender;The functionality of the oxime chain extender and hydrazide chain extender is independently ≥2 respectively.The self-repairing polyurethane elastomer of the present application has good mechanical properties, high self-repairing efficiency and good environmental resistance, and can be used in harsh environment;Solve the existing polyurethane self-repairing efficiency is low, the problem of poor performance under harsh conditions.

Description

Technical Field

[0001] This invention relates to the field of polyurethane materials technology, and in particular to a polyurethane elastomer, its preparation method, and its application. Background Technology

[0002] Polyurethane elastomers, due to their unique microphase separation structure and excellent mechanical properties, have wide applications in flexible electronics, smart materials, marine engineering, and biomedicine. However, traditional polyurethane materials often face two major challenges in practical use: first, they are prone to microcracks during long-term service, leading to performance degradation or even failure; second, their performance deteriorates sharply under complex operating conditions (such as strong acids, strong alkalis, high salt, and high humidity environments). Therefore, developing polyurethane elastomers that combine high strength and toughness, room temperature self-healing properties, and excellent environmental resistance is of great significance.

[0003] For example, CN111763474A discloses a high-adhesion, environmentally resistant transparent polyurethane coating, comprising coating agent A and coating agent B; coating agent A includes a polyol, chain extender, catalyst, bisphenol A type epoxy resin, solvent, leveling agent, wetting agent, nano titanium dioxide, and antibacterial agent; coating agent B includes an aliphatic diisocyanate; the polyurethane can resist various environmental erosions; however, the polyurethane does not possess self-healing properties. In contrast, existing polyurethanes with self-healing properties generally have poor environmental resistance.

[0004] Therefore, developing a polyurethane material that combines high self-healing efficiency, excellent environmental resistance, and good mechanical properties is an urgent problem to be solved in this field. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a polyurethane elastomer, its preparation method, and its applications. The polyurethane elastomer possesses excellent mechanical properties, high self-healing efficiency, and good environmental resistance, enabling its use in relatively harsh environments; thus solving the problems of low self-healing efficiency and poor performance under harsh conditions found in existing polyurethane products.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a polyurethane elastomer, wherein the raw materials for preparing the polyurethane elastomer include the following components: polytetramethylene ether glycol, polyisocyanate, oxime chain extender and acylhydrazine chain extender; wherein the functionality of the oxime chain extender and the acylhydrazine chain extender is independently ≥2, for example, 3, 4, 5, 6 or 7, etc.

[0007] In this invention, polytetramethylene ether glycol is selected as the soft segment. Its main chain is a polyether structure, lacking easily hydrolyzed ester groups, thus endowing the material with intrinsic hydrolysis resistance and hydrophobicity, which is the basis for its corrosion resistance. Oxime chain extenders and hydrazide chain extenders are selected as mixed chain extenders. These react with isocyanates to form oxime-carbamate bonds and urea bonds, respectively. The oxime-carbamate bonds are reversible at room temperature, which is key to the material's room-temperature self-healing capability; the urea bonds can form a high-density hydrogen bond network, giving the material high strength and toughness. The synergistic effect of these two dynamic interactions enables the material to achieve efficient self-healing even under alcohol stimulation at room temperature, while maintaining good mechanical properties and environmental resistance.

[0008] Preferably, the polytetramethylene ether glycol comprises a homopolymer of polytetrahydrofuran.

[0009] Preferably, the number average molecular weight of the polytetramethylene ether glycol is 1000-3000 g / mol, for example, it can be 1500 g / mol, 1800 g / mol, 2000 g / mol, 2300 g / mol or 2500 g / mol.

[0010] Preferably, the functionality of the polyisocyanate is ≥2, for example, it can be 3, 4, 5, 6 or 7, etc.

[0011] Preferably, the polyisocyanate comprises any one or a combination of at least two of dicyclohexane 4,4'-diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, phenylmethylene diisocyanate, or hexamethylene diisocyanate; more preferably, it is dicyclohexane 4,4'-diisocyanate.

[0012] Preferably, the oxime chain extender includes dimethylglyoxime.

[0013] Preferably, the acylhydrazide chain extender includes adipic acid dihydrazide.

[0014] In this invention, dimethylglyoxime and adipate dihydrazide are selected as mixed chain extenders. They react with isocyanates to form oxime-carbamate bonds and urea bonds, respectively. The oxime-carbamate bonds are reversible at room temperature, which is key to the material's room-temperature self-healing capability; the urea bonds form a high-density hydrogen bond network, endowing the material with high strength and toughness. The synergistic effect of these two dynamic interactions enables the material to achieve efficient self-healing even under room-temperature alcohol stimulation, while maintaining good mechanical properties and environmental resistance.

[0015] Preferably, the molar ratio of polytetramethylene ether glycol to polyisocyanate is 1:(1.5-10), for example, it can be 1:2, 1:3, 1:4, 1:5, 1:6 or 1:8, and more preferably 1:(2-5).

[0016] Preferably, the molar ratio of the oxime chain extender to polytetramethylene ether glycol is 1:(0.5-2), for example, it can be 1:0.8, 1:1, 1:1.2, 1:1.5 or 1:1.8, and more preferably 1:(0.8-2).

[0017] Preferably, the molar ratio of the hydrazide chain extender to polytetramethylene ether glycol is 1:(0.5-2), for example, it can be 1:0.8, 1:1, 1:1.2, 1:1.5 or 1:1.8, and more preferably 1:(0.8-1.2).

[0018] Preferably, the molar ratio of the sum of the moles of the oxime chain extender and the hydrazide chain extender to the moles of polytetramethylene ether glycol is 2:(0.8-1.2), for example, it can be 2:0.9, 2:0.95, 2:1, 2:1.05 or 2:1.1, etc.

[0019] Preferably, the molar ratio of the oxime chain extender to the hydrazide chain extender is (0.5-1.5):1, for example, it can be 0.6:1, 0.8:1, 1:1, 1.2:1 or 1.4:1, etc.

[0020] In a second aspect, the present invention provides a method for preparing a polyurethane elastomer as described in the first aspect, the method comprising the following steps: (1) Reaction of polytetramethylene ether glycol with polyisocyanate yields reactant A; (2) React reactant A obtained in step (1) with an oxime chain extender to obtain reactant B; (3) React reactant B obtained in step (2) with acylhydrazine chain extender to obtain the polyurethane elastomer.

[0021] Preferably, step (1) further includes a step of dehydrating polytetramethylene ether diol and polyisocyanate before the reaction.

[0022] Preferably, the method for removing water includes drying.

[0023] Preferably, the water content of the polytetramethylene ether glycol and the polyisocyanate is each independently <0.1 wt%, for example, it can be 0.02 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, or 0.08 wt%, etc.

[0024] Preferably, the reaction in step (1) is carried out in the presence of a protective atmosphere.

[0025] Preferably, the reaction in step (1) is carried out in the presence of a catalyst.

[0026] Preferably, the protective atmosphere comprises nitrogen.

[0027] Preferably, the catalyst comprises dibutyltin dilaurate.

[0028] Preferably, the mass of the catalyst is 0.05 wt% to 0.2 wt% of the sum of the masses of polytetramethylene ether glycol and polyisocyanate, for example, it can be 0.08 wt%, 0.1 wt%, 0.12 wt%, 0.15 wt% or 0.18 wt%, etc.

[0029] Preferably, the reaction temperature in step (1) is 60-90°C, for example, it can be 65°C, 70°C, 75°C, 80°C or 85°C.

[0030] Preferably, the reaction time in step (1) is 2-8 h, for example, it can be 3 h, 4 h, 5 h, 6 h or 7 h.

[0031] Preferably, the reaction in step (2) is carried out in the presence of solvent A.

[0032] Preferably, the mass ratio of the oxime chain extender to solvent A is 1:(5-15), for example, it can be 1:6, 1:8, 1:10, 1:12 or 1:14, etc.

[0033] Preferably, solvent A comprises N,N-dimethylformamide.

[0034] Preferably, the reaction temperature in step (2) is 50-80°C, for example, it can be 55°C, 60°C, 65°C, 70°C or 75°C.

[0035] Preferably, the reaction time in step (2) is 2-6 h, for example, it can be 3 h, 3.5 h, 4 h, 4.5 h or 5 h.

[0036] Preferably, the reaction in step (3) is carried out in the presence of solvent B.

[0037] Preferably, the mass ratio of the hydrazide chain extender to solvent B is 1:(5-15), 1:6, 1:8, 1:10, 1:12, or 1:14, etc.

[0038] Preferably, solvent B comprises N,N-dimethylformamide.

[0039] Preferably, the reaction temperature in step (3) is 60-90°C, for example, it can be 65°C, 70°C, 75°C, 80°C or 85°C.

[0040] Preferably, the reaction time in step (3) is 8-24 h, for example, it can be 10 h, 12 h, 15 h, 16 h, 18 h or 20 h.

[0041] Preferably, the reaction in step (3) is followed by a drying step.

[0042] Preferably, the drying temperature is 60-100℃, for example, it can be 70℃, 75℃, 80℃, 85℃ or 90℃.

[0043] Preferably, the drying time is 24-72 h, for example, it can be 30 h, 36 h, 48 h, 60 h or 66 h.

[0044] Preferably, the vacuum degree during drying is -0.08 to -0.1 MPa, for example, it can be -0.085 MPa, -0.088 MPa, -0.09 MPa, -0.095 MPa or -0.098 MPa, etc.

[0045] Preferably, the preparation method includes the following steps: (1) Under a protective atmosphere, polytetramethylene ether glycol is mixed with polyisocyanate and catalyst and reacted at 60-90℃ for 2-8 h to obtain reactant A; (2) Mix the oxime chain extender with solvent A, and then react the resulting solution with reactant A at 50-80℃ for 2-6 h to obtain reactant B; (3) Mix the hydrazide chain extender with solvent B, and then react the resulting solution with reactant B at 60-90℃ for 8-24 h, and then dry at 60-100℃ and -0.08~-0.1 MPa for 24-72 h to obtain the polyurethane elastomer.

[0046] In this invention, the preparation method of the polyurethane elastomer is mild, simple, and easy to scale up for production.

[0047] Thirdly, the present invention provides a self-healing material, the self-healing material comprising the polyurethane elastomer described in the first aspect.

[0048] Compared with the prior art, the present invention has at least the following beneficial effects: The high-strength, high-toughness, self-healing polyurethane elastomer provided by this invention uses polytetramethylene ether glycol as the soft segment, endowing the material with intrinsic hydrophobicity and hydrolysis resistance; and introduces reversible oxime-carbamate bonds and a high-density hydrogen bond network into the hard segment using dimethylglyoxime and adipate dihydrazide as mixed chain extenders. The synergistic effect of these two dynamic interactions enables the material to achieve efficient self-healing even under room-temperature alcohol stimulation, while simultaneously endowing the material with excellent mechanical properties and environmental resistance.

[0049] The polyurethane elastomer provided by this invention exhibits a tensile strength repair efficiency of ≥94% and an elongation at break repair efficiency of ≥83% after self-healing for 24 hours at room temperature; tensile strength ≥38 MPa and elongation at break ≥830%; and mechanical properties show almost no degradation after continuous immersion in pH=2, pH=14, artificial seawater, and pure water for 10 days.

[0050] The polyurethane elastomer provided by this invention has high self-healing efficiency and high tensile strength at room temperature. It also exhibits excellent mechanical property retention after long-term immersion in strong acids, strong alkalis, artificial seawater, and pure water, and has broad application prospects in fields such as flexible electronics, intelligent repair, and marine engineering. Detailed Implementation

[0051] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0052] Unless otherwise specified, all materials used in this invention can be purchased commercially or prepared using conventional methods.

[0053] Example 1 A polyurethane elastomer and its preparation method are disclosed. The raw materials for preparing the polyurethane elastomer include polytetramethylene ether glycol (number average molecular weight 2000 g / mol), dicyclohexylmethane diisocyanate, dimethylglyoxime, and adipate dihydrazide. The molar ratio of polytetramethylene ether glycol to dicyclohexylmethane diisocyanate is 1:3, the molar ratio of dimethylglyoxime to polytetramethylene ether glycol is 1:1, and the molar ratio of adipate dihydrazide to polytetramethylene ether glycol is 1:1 (i.e., the molar ratio of dimethylglyoxime to adipate dihydrazide is 1:1). The mass of polytetramethylene ether glycol is 20.0 g.

[0054] The preparation method includes the following steps: (1) Polytetramethylene ether glycol and dicyclohexylmethane diisocyanate were added to a three-necked flask, followed by the addition of 0.1 wt% dibutyltin dilaurate, which is the total mass of polytetramethylene ether glycol and dicyclohexylmethane diisocyanate. The mixture was reacted for 2 h under a nitrogen atmosphere and at a temperature of 80 °C to obtain reactant A.

[0055] (2) Subsequently, dimethylglyoxime was dissolved in 10 g of N,N-dimethylformamide, and the resulting solution was added to reactant A obtained in step (1). The reaction was continued at 60°C for 2 h to obtain reactant B.

[0056] (3) Dissolve adipic dihydrazide in 15 g N,N-dimethylformamide, add the resulting solution to reactant B obtained in step (2), react at 80°C for 12 h, then place it in a mold, put it in a vacuum oven and dry at 80°C for 48 h to remove N,N-dimethylformamide, and obtain the polyurethane elastomer.

[0057] Example 2 A polyurethane elastomer and its preparation method are disclosed. The only difference from Example 1 is that the molar ratio of dimethylglyoxime to polytetramethylene ether glycol is 1:1.5, and the molar ratio of adipate dihydrazide to polytetramethylene ether glycol is 1:1 (i.e., the molar ratio of dimethylglyoxime to adipate dihydrazide is 0.67:1). All other raw materials, amounts, and preparation methods are the same as in Example 1.

[0058] Example 3 A polyurethane elastomer and its preparation method are disclosed. The only difference from Example 1 is that the molar ratio of dimethylglyoxime to polytetramethylene ether glycol is 1:1, and the molar ratio of adipate dihydrazide to polytetramethylene ether glycol is 1:1.5 (i.e., the molar ratio of dimethylglyoxime to adipate dihydrazide is 1:0.67). All other raw materials, amounts, and preparation methods are the same as in Example 1.

[0059] Example 4 A polyurethane elastomer and its preparation method are disclosed. The only difference from Example 1 is that dicyclohexylmethane diisocyanate is replaced with an equimolar amount of isophorone diisocyanate; all other raw materials, amounts, and preparation methods are the same as in Example 1.

[0060] Example 5 A polyurethane elastomer and its preparation method are disclosed. The only difference from Example 1 is that the average molecular weight of the polytetramethylene ether glycol is 1000 g / mol; all other raw materials, amounts, and preparation methods are the same as in Example 1.

[0061] Example 6 A polyurethane elastomer and its preparation method are disclosed. The only difference from Example 1 is that the molar ratio of dimethylglyoxime to polytetramethylene ether glycol is 1:0.8, and the molar ratio of adipate dihydrazide to polytetramethylene ether glycol is 1:0.8 (i.e., the molar ratio of dimethylglyoxime to adipate dihydrazide is 1:1). All other raw materials, amounts, and preparation methods are the same as in Example 1.

[0062] Example 7 A polyurethane elastomer and its preparation method are disclosed. The only difference from Example 1 is that the molar ratio of dimethylglyoxime to polytetramethylene ether glycol is 1:1.2, and the molar ratio of adipate dihydrazide to polytetramethylene ether glycol is 1:1.2 (i.e., the molar ratio of dimethylglyoxime to adipate dihydrazide is 1:1). All other raw materials, amounts, and preparation methods are the same as in Example 1.

[0063] Example 8 A polyurethane elastomer and its preparation method are disclosed. The only difference from Example 1 is that the molar ratio of dimethylglyoxime to polytetramethylene ether glycol is 1:2.5, and the molar ratio of adipate dihydrazide to polytetramethylene ether glycol is 1:2.5 (i.e., the molar ratio of dimethylglyoxime to adipate dihydrazide is 1:1). All other raw materials, amounts, and preparation methods are the same as in Example 1.

[0064] Comparative Example 1 A polyurethane elastomer and its preparation method are disclosed. The only difference from Example 1 is that dimethylglyoxime is not added to the raw materials used in this preparation (i.e., only adipic acid dihydrazide is used as a chain extender), and the amount of adipic acid dihydrazide used is the same as the total molar amount of dimethylglyoxime and adipic acid dihydrazide in Example 1. Other raw materials, amounts, and preparation methods are the same as in Example 1.

[0065] Specifically, the preparation method includes the following steps: (1) Polytetramethylene ether glycol and dicyclohexylmethane diisocyanate were added to a three-necked flask, followed by the addition of 0.1 wt% dibutyltin dilaurate, which is the total mass of polytetramethylene ether glycol and dicyclohexylmethane diisocyanate. The mixture was reacted for 2 h under a nitrogen atmosphere and at a temperature of 80 °C to obtain reactant A.

[0066] (2) Subsequently, adipic acid dihydrazide was dissolved in 15 g of N,N-dimethylformamide, and the resulting solution was added to reactant A obtained in step (1). The reaction was carried out at 80°C for 12 h, and then placed in a mold and dried in a vacuum oven at 80°C for 48 h. After removing N,N-dimethylformamide, the polyurethane elastomer was obtained.

[0067] Comparative Example 2 A polyurethane elastomer and its preparation method are disclosed. The only difference from Example 1 is that adipate dihydrazide is not added to the raw materials used in this preparation (i.e., only dimethylglyoxime is used as a chain extender), and the amount of dimethylglyoxime is the same as the total molar amount of dimethylglyoxime and adipate dihydrazide in Example 1. The other raw materials, amounts, and preparation methods are the same as in Example 1.

[0068] Specifically, the preparation method includes the following steps: (1) Polytetramethylene ether glycol and dicyclohexylmethane diisocyanate were added to a three-necked flask, followed by the addition of 0.1 wt% dibutyltin dilaurate, which is the total mass of polytetramethylene ether glycol and dicyclohexylmethane diisocyanate. The mixture was reacted for 2 h under a nitrogen atmosphere and at a temperature of 80 °C to obtain reactant A.

[0069] (2) Subsequently, dimethylglyoxime was dissolved in 10 g of N,N-dimethylformamide, and the resulting solution was added to reactant A obtained in step (1). The reaction was continued at 60°C for 2 h. Then, it was placed in a mold and dried in a vacuum oven at 80°C for 48 h to remove N,N-dimethylformamide, and the polyurethane elastomer was obtained.

[0070] Comparative Example 3 A polyurethane elastomer and its preparation method are disclosed. The only difference from Example 1 is that polytetramethylene ether glycol is replaced with polycaprolactone glycol (PCL2000) of equal average molecular weight. All other raw materials, amounts, and preparation methods are the same as in Example 1.

[0071] Test methods (1) Tensile strength: The tensile mechanical properties of the polyurethane elastomers provided in the examples and comparative examples were tested using an electronic universal testing machine at room temperature (23±2℃). The polyurethane elastomer samples were cut into dumbbell shapes with a gauge length of 20 mm (Lo), a width of 4 mm, and a thickness of 1 mm. The tensile rate was set to a constant strain rate of 100 mm / min. A 100 N load cell was selected as the tensile mechanical sensor.

[0072] (2) Self-healing efficiency: After cutting the dumbbell-shaped polyurethane elastomer in half with a scalpel, the fractured surfaces were moistened with ethanol and then spliced ​​together. The elastomer was allowed to heal at room temperature for 24 hours without any external force applied. The self-healing efficiency was expressed by the retention rate of tensile strength of the material before and after healing. The formula for calculating the self-healing efficiency (HE) is as follows: Where HE represents the self-healing efficiency, σ self healed σ represents the tensile strength after healing. original This indicates the initial tensile strength (i.e., the tensile strength of the material before self-healing).

[0073] (3) Environmental resistance: 50 mL of hydrochloric acid solution (pH=2), sodium hydroxide solution (pH=14), and artificial seawater (Shanghai Maclean Biochemical Technology Co., Ltd., A769002) were respectively placed in glassware. The prepared polyurethane elastomer sample was then immersed in these solutions for 10 days. The immersed polyurethane elastomer was then subjected to a tensile test according to method (1). The environmental resistance was represented by the tensile strength retention rate before and after immersion. The tensile strength retention rate CE was calculated according to the following formula: Where CE represents the tensile strength retention rate, σ corroded σ represents the tensile strength of the material after immersion. original This indicates the initial tensile strength.

[0074] The mechanical properties and self-healing efficiency test results of polyurethane elastomers are shown in Table 1, and the environmental resistance (tensile strength retention rate after 10 days of immersion) test results are shown in Table 2.

[0075] Table 1 Table 2 The test results show that: (1) As can be seen from Examples 1-8, the high-strength and tough self-healing polyurethane elastomer provided by the present invention, by selecting polytetramethylene ether glycol as the soft segment and introducing oxime-carbamate bonds and urea bonds in the hard segment, the resulting polyurethane has good mechanical properties, room temperature self-healing efficiency and excellent environmental corrosion resistance.

[0076] In Example 1, the polyurethane elastomer self-heals for 24 hours at room temperature, with a self-healing efficiency of 94.2%. The tensile strength of the self-healing elastomers in Examples 1-7 can reach 30-38 MPa, and the elongation at break can reach 680%-839%. After being continuously immersed in pH=2, pH=14, artificial seawater, and pure water for 10 days, the mechanical properties of the polyurethane elastomer in Example 1 retain ≥95%.

[0077] (2) By comparing Example 1 with Examples 2-7, it can be seen that the present invention further limits the ratio and amount of amine chain extender and hydrazide chain extender, the type of polyisocyanate and the molecular weight of polytetramethylene ether glycol, thereby improving the performance of the polyurethane elastomer.

[0078] A comparison between Example 1 and Example 8 shows that when the amount of chain extender is too small, the mechanical properties and self-healing efficiency of the material decrease significantly.

[0079] (3) By comparing Example 1 with Comparative Examples 1-2, it can be seen that the simultaneous use of oxime chain extenders and hydrazide chain extenders, with their synergistic effect, can simultaneously endow the material with high self-healing efficiency and high mechanical properties.

[0080] A comparison between Example 1 and Comparative Example 3 shows that, under the same conditions, the polyurethane obtained by using polytetramethylene ether glycol as the soft segment has superior corrosion resistance.

[0081] In summary, by selecting specific raw materials and using simple polymerization conditions, this invention can endow self-healing polyurethane elastomers with excellent mechanical properties, room temperature self-healing properties, and environmental resistance.

[0082] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A polyurethane elastomer, characterized in that, The raw materials for preparing the polyurethane elastomer include the following components: polytetramethylene ether glycol, polyisocyanate, oxime chain extender and acylhydrazine chain extender; The functionality of the oxime chain extender and the hydrazide chain extender is independently ≥2.

2. The polyurethane elastomer according to claim 1, characterized in that, The polytetramethylene ether glycol includes a homopolymer of polytetrahydrofuran; Preferably, the number-average molecular weight of the polytetramethylene ether glycol is 1000-3000 g / mol.

3. The polyurethane elastomer according to claim 1 or 2, characterized in that, The functionality of the polyisocyanate is ≥2; Preferably, the polyisocyanate comprises any one or a combination of at least two of dicyclohexane 4,4'-diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, phenylmethylene diisocyanate or hexamethylene diisocyanate, and more preferably dicyclohexane 4,4'-diisocyanate.

4. The polyurethane elastomer according to any one of claims 1-3, characterized in that, The oxime chain extenders include dimethylglyoxime; Preferably, the acylhydrazide chain extender includes adipic acid dihydrazide.

5. The polyurethane elastomer according to any one of claims 1-4, characterized in that, The molar ratio of polytetramethylene ether diol to polyisocyanate is 1:(1.5-10), more preferably 1:(2-5); Preferably, the molar ratio of the oxime chain extender to polytetramethylene ether glycol is 1:(0.5-2), more preferably 1:(0.8-2); Preferably, the molar ratio of the hydrazide chain extender to polytetramethylene ether glycol is 1:(0.5-2), more preferably 1:(0.8-1.2); Preferably, the molar ratio of the sum of the molar numbers of the oxime chain extender and the hydrazide chain extender to the molar number of polytetramethylene ether glycol is 2:(0.8-1.2); Preferably, the molar ratio of the oxime chain extender to the hydrazide chain extender is (0.5-1.5):

1.

6. A method for preparing a polyurethane elastomer as described in any one of claims 1-5, characterized in that, The preparation method includes the following steps: (1) Reaction of polytetramethylene ether diol with polyisocyanate yields reactant A; (2) React reactant A obtained in step (1) with an oxime chain extender to obtain reactant B; (3) React reactant B obtained in step (2) with acylhydrazine chain extender to obtain the polyurethane elastomer.

7. The preparation method according to claim 6, characterized in that, The reaction described in step (1) is carried out in the presence of a protective atmosphere; Preferably, the reaction in step (1) is carried out in the presence of a catalyst; Preferably, the protective atmosphere includes nitrogen; Preferably, the catalyst comprises dibutyltin dilaurate; Preferably, the mass of the catalyst is 0.05 wt%-0.2 wt% of the sum of the masses of polytetramethylene ether glycol and polyisocyanate. Preferably, the reaction temperature in step (1) is 60-90℃; Preferably, the reaction time in step (1) is 2-8 h.

8. The preparation method according to claim 6 or 7, characterized in that, The reaction described in step (2) is carried out in the presence of solvent A; Preferably, the mass ratio of the oxime chain extender to solvent A is 1:(5-15); Preferably, solvent A comprises N,N-dimethylformamide; Preferably, the reaction temperature in step (2) is 50-80℃; Preferably, the reaction time in step (2) is 2-6 h.

9. The preparation method according to any one of claims 6-8, characterized in that, The reaction described in step (3) is carried out in the presence of solvent B; Preferably, the mass ratio of the hydrazide chain extender to solvent B is 1:(5-15); Preferably, solvent B comprises N,N-dimethylformamide; Preferably, the reaction temperature in step (3) is 60-90℃; Preferably, the reaction time in step (3) is 8-24 h; Preferably, the reaction in step (3) is followed by a drying step; Preferably, the drying temperature is 60-100℃; Preferably, the drying time is 24-72 h; Preferably, the vacuum degree during drying is -0.08 to -0.1 MPa.

10. A self-healing material, characterized in that, The self-healing material includes the polyurethane elastomer as described in any one of claims 1-5.

Images