A bio-based self-healing polyurethane, its preparation method and application

Abstract

This application provides a bio-based self-healing polyurethane, its preparation method, and its application. The raw materials, by weight, include: 40-60 parts of bio-based cyclic carbonate polyol, 20-30 parts of bio-based diamine, 5-10 parts of dynamic coordination crosslinking agent, 3-8 parts of chain extender, 0.5-2 parts of catalyst, and 0.1-0.5 parts of antioxidant. The dynamic coordination crosslinking agent is a complex formed by the coordination of zinc ions and tannic acid, with a molar ratio of zinc ions to tannic acid of 1:2 to 1:3. This polyurethane achieves rapid self-healing at room temperature through the synergistic effect of coordination bonds and dynamic hydrogen bonds. It possesses excellent mechanical properties and high bio-based content, is environmentally friendly, and exhibits good stability, making it widely applicable in flexible electronics, medical devices, and wear-resistant sealing materials.

Description

Technical Field

[0001] This application relates to the field of polyurethane materials technology, specifically to a bio-based self-healing polyurethane, its preparation method, and its application. Background Technology

[0002] Polyurethane materials are widely used in flexible electronics, medical devices, automotive parts, sealing materials, and high-end coatings due to their excellent wear resistance, flexibility, chemical corrosion resistance, and mechanical properties. With the increasing demand for functional and green materials, polyurethane materials that combine environmental friendliness and durability have become a key focus of industry research.

[0003] Currently, conventional polyurethanes are mostly prepared using petroleum-based polyols and isocyanates as the main raw materials. These materials not only have low bio-based content and are non-renewable, but isocyanates also possess a certain degree of toxicity, posing safety and environmental risks during production and use, and making it difficult to meet increasingly stringent environmental protection requirements. Furthermore, traditional polyurethanes are prone to microcracks and localized damage during long-term use due to external scratches, fatigue stress, and environmental aging. Accumulated damage significantly reduces the material's mechanical properties and service life, and manual repair is difficult and costly.

[0004] To address these issues, existing technologies attempt to introduce self-healing structures to extend material lifespan or utilize bio-based raw materials to improve environmental friendliness. However, existing bio-based polyurethanes generally suffer from drawbacks such as low mechanical strength, poor thermal stability, and limited functionality. Furthermore, existing self-healing polyurethanes often rely on single dynamic bonds or external stimuli for repair, resulting in low room-temperature self-healing efficiency, stringent repair conditions, and difficulties in balancing mechanical and self-healing properties. In addition, most systems fail to achieve effective synergy between bio-based raw materials and dynamic self-healing networks, making it difficult to balance environmental friendliness, mechanical strength, and self-healing capabilities, thus limiting their application in high-end equipment, wearable devices, and precision sealing.

[0005] Therefore, developing a polyurethane material with high bio-based content, low toxicity, excellent mechanical properties, and room-temperature self-healing ability has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] This application aims to address the shortcomings of existing related technologies by providing a bio-based self-healing polyurethane, its preparation method, and its application. It solves the technical problems of existing polyurethane materials, such as low bio-based content, reliance on toxic isocyanate raw materials, low efficiency requiring external stimulation for self-healing, and an imbalance between mechanical and self-healing properties. The new application achieves high bio-based content, is green, non-toxic, and odorless, and can self-heal at room temperature for 1-3 hours (self-healing efficiency ≥95%), with a tensile strength ≥30MPa. It also ensures excellent aging resistance and environmental compatibility, meeting the demand for high-performance, environmentally friendly materials in fields such as flexible electronics, medical devices, automotive interiors, and sealing materials.

[0007] The first aspect of this application provides a bio-based self-healing polyurethane, the raw materials of which, by weight, comprise: 40-60 parts of bio-based cyclic carbonate polyol, 20-30 parts of bio-based diamine, 5-10 parts of dynamic coordination crosslinking agent, 3-8 parts of chain extender, 0.5-2 parts of catalyst, and 0.1-0.5 parts of antioxidant; wherein the dynamic coordination crosslinking agent is a complex formed by the coordination of zinc ions and tannic acid, and the molar ratio of zinc ions to tannic acid is 1:2 to 1:3.

[0008] Furthermore, the bio-based cyclic carbonate polyol is prepared by using castor oil as a starting material, followed by ring-opening polymerization of propylene oxide and then cycloaddition reaction with carbon dioxide; the hydroxyl value of the bio-based cyclic carbonate polyol is 180-220 mg KOH / g, and the bio-based content is not less than 85% by mass.

[0009] Furthermore, the bio-based diamine is selected from bio-based decanediamine or lysine-based diamine; the bio-based content of the bio-based diamine is ≥98% by weight.

[0010] Furthermore, the chain extender is selected from one or a mixture of two of 1,4-butanediol and bio-based 1,6-hexanediol.

[0011] Furthermore, the catalyst is a bimetallic cyanide catalyst, and the active component of the bimetallic cyanide catalyst is selected from zinc-cobalt bimetallic cyanide or zinc-iron bimetallic cyanide.

[0012] Furthermore, the antioxidant is selected from one or a mixture of at least two of tea polyphenols, vitamin E, and beta-carotene.

[0013] A second aspect of this application provides a method for preparing a bio-based self-healing polyurethane, the method comprising: Castor oil is used as the starting material and mixed with propylene oxide at a mass ratio of 1:3 to 1:5. A bimetallic cyanide catalyst is added, and polymerization is carried out at 120 to 140°C for 3 to 5 hours to obtain a polyether polyol. Carbon dioxide is introduced into the polyether polyol, and the reaction pressure is controlled at 0.5 to 1.0 MPa and the temperature at 80 to 100°C for 6 to 8 hours to obtain a bio-based cyclic carbonate polyol with a hydroxyl value of 180 to 220 mg KOH / g and a bio-based content of ≥85% by mass. Tannic acid was dissolved in deionized water to prepare a 5-10% (w / w) aqueous solution of tannic acid. A 0.5 mol / L zinc salt solution was slowly added dropwise to adjust the pH of the system to 6.5-7.5. The reaction was carried out at 40-60℃ for 2-3 hours. After filtration and freeze-drying, a dynamic coordination crosslinking agent with a zinc ion to tannic acid molar ratio of 1:2 to 1:3 was obtained. By weight, 40-60 parts of bio-based cyclic carbonate polyol, 20-30 parts of bio-based diamine, 5-10 parts of dynamic coordination crosslinking agent, and 3-8 parts of chain extender are added to a reactor. Under nitrogen protection, the temperature is raised to 100-120°C and stirred for 1-2 hours. The temperature is then lowered to 70-80°C, and 0.5-2 parts of bimetallic cyanide catalyst and 0.1-0.5 parts of antioxidant are added. The reaction is continued to be stirred for 3-4 hours to obtain a polymer product. The polymer product is poured into a mold and cured at room temperature for 24 hours to obtain bio-based self-healing polyurethane.

[0014] Furthermore, the active component of the bimetallic cyanide catalyst is selected from zinc-cobalt bimetallic cyanide or zinc-iron bimetallic cyanide, and the amount of catalyst added is 0.1 to 0.3% of the total mass of castor oil and propylene oxide.

[0015] Furthermore, the zinc salt is selected from zinc chloride and zinc sulfate, and the dropping rate of the zinc salt solution is 1-3 mL / min.

[0016] A third aspect of this application provides the application of bio-based self-healing polyurethane in flexible electronic device packaging and surface protective coatings.

[0017] Beneficial effects By using bio-based cyclic carbonate polyols and bio-based diamines to construct the core reaction system, the traditional petroleum-based raw materials and toxic isocyanates are replaced. This improves the bio-based content and environmental friendliness of the materials from the source, avoiding the volatile toxicity, irritating odor, and residual toxicity of isocyanates. At the same time, bio-based raw materials are renewable, reducing dependence on fossil resources and making the materials more suitable for scenarios with high safety requirements, such as medical devices and wearable devices.

[0018] By introducing a complex formed by the coordination of zinc ions and tannic acid as a dynamic coordination crosslinking agent, and limiting the molar ratio of zinc ions to tannic acid to 1:2 to 1:3, the dynamic coordination bonds formed under this ratio can spontaneously dissociate and recombine when the material is damaged. Combined with the dynamic hydrogen bonds formed during the reaction of bio-based cyclic carbonate polyols and bio-based diamines, a dual dynamic synergistic network of coordination bonds and hydrogen bonds is constructed. It can achieve efficient self-healing at room temperature without external stimulation, effectively repairing microcracks, scratches and other damage generated during use, and extending the service life of the material. The ratio of 40-60 parts bio-based cyclic carbonate polyol and 20-30 parts bio-based diamine ensures a complete reaction, forming a structurally stable polyurethane backbone. 5-10 parts dynamic coordination crosslinking agent provides sufficient dynamic crosslinking sites without damaging the backbone structure. The specific structural synergistic effect of each raw material by weight and the dynamic coordination crosslinking agent enables the material to possess both highly efficient self-healing properties and excellent mechanical properties, such as high tensile strength, good flexibility, and elasticity. This avoids the problem of difficulty in balancing self-healing properties and mechanical properties in existing technologies. Furthermore, the overall system is green and environmentally friendly, highly stable, and widely applicable, meeting the needs of multiple fields such as flexible electronics, automotive parts, sealing materials, and medical devices. Detailed Implementation

[0019] Example 1: Step 1: Preparation of bio-based cyclic carbonate polyols 20.0 g of castor oil was added to a 500 mL three-necked flask, and the mixture was heated to 80 °C and vacuum dehydrated for 2 h to remove moisture. The temperature was then lowered to 60 °C, and 80.0 g of propylene oxide (castor oil to propylene oxide mass ratio 1:4) was added, followed by 0.15 g of Zn-Co DMC catalyst (0.15% of the total mass of castor oil and propylene oxide). The air in the flask was purged with nitrogen three times, and the temperature was raised to 130 °C. The polymerization reaction was carried out at a stirring rate of 300 r / min for 4 h. After the reaction was completed, the temperature was lowered to 90 °C, carbon dioxide gas was introduced, and the reaction pressure was controlled at 0.8 MPa. The stirring rate was 250 r / min, and the cycloaddition reaction was carried out for 7 h. After depressurization, the mixture was cooled to room temperature to obtain a bio-based cyclic carbonate polyol. The hydroxyl value was measured to be 200 mg KOH / g, and the bio-based content was 85% (by mass).

[0020] Step 2: Preparation of zinc ion-tannic acid complex Take 4.0 g of tannic acid, add 50 mL of deionized water, stir to dissolve, and prepare an 8% (w / w) tannic acid aqueous solution; weigh 2.3 g of zinc chloride, add 40 mL of deionized water, and prepare a 0.5 mol / L zinc chloride solution; place the tannic acid aqueous solution in a constant temperature water bath, heat to 50 °C, and adjust the pH to 7.0; slowly add the zinc chloride solution dropwise at a rate of 2 mL / min, and continue to react at 50 °C for 2.5 h, maintaining a stirring rate of 150 r / min during this period; after the reaction is complete, filter to collect the precipitate, and place it in a freeze dryer to dry for 12 h to obtain 8.0 g of dynamic coordination crosslinking agent.

[0021] Step 3: Polymerization to prepare bio-based self-healing polyurethane Take a 500mL four-necked reactor and add 50.0g of the bio-based cyclic carbonate polyol and 25.0g of the bio-based decanediamine prepared in step 1, 8.0g of the dynamic coordination crosslinking agent prepared in step 2, and 5.0g of the chain extender bio-based 1,6-hexanediol. Replace the air in the reactor with nitrogen three times, set the stirring speed to 300r / min, raise the temperature to 110℃, and keep the reaction at this temperature for 1.5h. Cool down to 75℃, add 1.0g of the catalyst Zn-Co DMC and 0.3g of the antioxidant tea polyphenols, and continue stirring for 3.5h. After the reaction is completed, pour the polymer product into a polytetrafluoroethylene mold, place it in a constant temperature and humidity chamber, cure at room temperature for 24h, and demold to obtain the bio-based self-healing polyurethane sample.

[0022] Example 2: Step 1: Preparation of bio-based cyclic carbonate polyols 18.0 g of castor oil was added to a 500 mL three-necked flask and heated to 80 °C for vacuum dehydration for 2.5 h to remove moisture. The temperature was then lowered to 60 °C, and 72.0 g of propylene oxide (castor oil to propylene oxide mass ratio 1:4) was added, along with 0.135 g of Zn-Co DMC catalyst (0.15% of the total mass of castor oil and propylene oxide). The air in the flask was replaced with nitrogen three times, and the temperature was raised to 125 °C. The stirring speed was 300 r / min, and the polymerization reaction was carried out for 4.5 h. After the reaction, the temperature was lowered to 85 °C, carbon dioxide gas was introduced, and the reaction pressure was controlled at 0.7 MPa. The stirring speed was 250 r / min, and the cycloaddition reaction was carried out for 7.5 h. The pressure was slowly released to atmospheric pressure, cooled to room temperature, and filtered to remove trace impurities, yielding a bio-based cyclic carbonate polyol. The hydroxyl value was measured to be 180 mg KOH / g, and the bio-based content was 85% (by mass).

[0023] Step 2: Preparation of zinc ion-tannic acid complex Take 3.0 g of tannic acid, add 37.5 mL of deionized water, stir to dissolve, and prepare an 8% (w / w) tannic acid aqueous solution; weigh 1.7 g of zinc chloride, add 30 mL of deionized water, and prepare a 0.5 mol / L zinc chloride solution; place the tannic acid aqueous solution in a constant temperature water bath, heat to 48℃, and adjust the pH to 6.8 with 0.1 mol / L NaOH solution; slowly add the zinc chloride solution dropwise at a rate of 1.8 mL / min, and after the addition is complete, continue the reaction at 48℃ for 2.3 h, maintaining a stirring rate of 150 r / min during this period; after the reaction is complete, filter and collect the precipitate, wash the precipitate three times with deionized water, and place it in a freeze dryer to dry for 14 h to obtain 6.0 g of dynamic coordination crosslinking agent (Zn 2+ (Molar ratio with tannic acid 1:2.5).

[0024] Step 3: Polymerization to prepare bio-based self-healing polyurethane Take a 500mL four-necked reactor and add 45.0g of the bio-based cyclic carbonate polyol, 28.0g of the bio-based decanediamine, 6.0g of the dynamic coordination crosslinking agent, and 3.0g of the chain extender bio-based 1,6-hexanediol. Replace the air in the reactor with nitrogen three times, set the stirring speed to 280r / min, heat to 105℃ (heating rate 5℃ / min), and keep the temperature for 1.8h. Cool down to 72℃ (cooling rate 3℃ / min), add 0.8g of the catalyst Zn-Co DMC and 0.2g of the antioxidant tea polyphenols, and continue stirring for 3.8h. After the reaction is completed, pour the polymer product into a polytetrafluoroethylene mold, place it in a constant temperature and humidity chamber, cure at room temperature for 24h, and demold to obtain the bio-based self-healing polyurethane sample.

[0025] Example 3: Step 1: Preparation of bio-based cyclic carbonate polyols 22.0 g of castor oil was added to a 500 mL three-necked flask and heated to 85 °C for vacuum dehydration for 2 h to remove moisture. The temperature was then lowered to 60 °C, and 88.0 g of propylene oxide (castor oil to propylene oxide mass ratio 1:4) was added, along with 0.165 g of Zn-Co DMC catalyst (0.15% of the total mass of castor oil and propylene oxide). The air in the flask was replaced with nitrogen three times, and the temperature was raised to 135 °C. The stirring rate was 320 r / min, and the polymerization reaction was carried out for 3.5 h. After the reaction, the temperature was lowered to 95 °C, carbon dioxide gas was introduced, and the reaction pressure was controlled at 0.9 MPa. The stirring rate was 280 r / min, and the cycloaddition reaction was carried out for 6.5 h. The pressure was slowly released to atmospheric pressure, cooled to room temperature, and filtered to remove trace impurities, yielding a bio-based cyclic carbonate polyol. The hydroxyl value was measured to be 220 mg KOH / g, and the bio-based content was 85% (by mass).

[0026] Step 2: Preparation of zinc ion-tannic acid complex Take 4.5g of tannic acid, add 56.25mL of deionized water, stir to dissolve, and prepare an 8% (w / w) tannic acid aqueous solution; weigh 2.6g of zinc chloride, add 45mL of deionized water, and prepare a 0.5mol / L zinc chloride solution; place the tannic acid aqueous solution in a constant temperature water bath, heat to 52℃, and adjust the pH to 7.2 with 0.1mol / L NaOH solution; slowly add the zinc chloride solution dropwise at a rate of 2.2mL / min, and after the addition is complete, continue the reaction at 52℃ for 2.7h, maintaining a stirring rate of 180r / min during this period; after the reaction is complete, filter and collect the precipitate, wash the precipitate three times with deionized water, and place it in a freeze dryer to dry for 13h to obtain 9.0g of dynamic coordination crosslinking agent (Zn 2+ (Molar ratio with tannic acid 1:2.5).

[0027] Step 3: Polymerization to prepare bio-based self-healing polyurethane Take a 500mL four-necked reactor and add 55.0g of the bio-based cyclic carbonate polyol prepared in step 1, 22.0g of the bio-based decanediamine, 9.0g of the dynamic coordination crosslinking agent prepared in step 2, and 7.0g of the chain extender bio-based 1,6-hexanediol. Replace the air in the reactor with nitrogen three times, set the stirring speed to 320r / min, raise the temperature to 115℃, and keep the reaction at this temperature for 1.2h. Cool down to 78℃, add 1.5g of the catalyst Zn-Co DMC and 0.4g of the antioxidant tea polyphenols, and continue stirring for 3.2h. After the reaction is completed, pour the polymer product into a polytetrafluoroethylene mold, place it in a constant temperature and humidity chamber, cure at room temperature for 24h, and demold to obtain the bio-based self-healing polyurethane sample.

[0028] Comparative Example 1: Step 1: Preparation of bio-based cyclic carbonate polyols It is completely consistent with step 1 of Example 1.

[0029] Step 2: Polymerization to prepare polyurethane Take a 500mL four-necked reactor and add 50.0g of the bio-based cyclic carbonate polyol, 25.0g of the bio-based decanediamine, and 5.0g of the chain extender bio-based 1,6-hexanediol (without dynamic coordination crosslinking agent) prepared in step 1. Replace the air in the reactor with nitrogen three times, set the stirring speed to 300r / min, raise the temperature to 110℃, and keep the reaction at this temperature for 1.5h. Cool down to 75℃, add 1.0g of the catalyst Zn-Co DMC and 0.3g of the antioxidant tea polyphenol, and continue stirring for 3.5h. After the reaction is completed, pour the polymer product into a polytetrafluoroethylene mold, place it in a constant temperature and humidity chamber, cure at room temperature for 24h, and demold to obtain the polyurethane sample of Comparative Example 1.

[0030] Comparative Example 2: Step 1: No bio-based cyclic carbonate polyol preparation step, directly using commercially available petroleum-based polyether polyol.

[0031] Step 2: Preparation of zinc ion-tannic acid complex It is completely consistent with step 2 of Example 1.

[0032] Step 3: Polymerization to prepare polyurethane Take a 500mL four-necked reactor and add 50.0g of petroleum-based polyether polyol, 25.0g of bio-based decanediamine, 8.0g of the dynamic coordination crosslinking agent prepared in step 2, and 5.0g of the chain extender bio-based 1,6-hexanediol. Replace the air in the reactor with nitrogen three times, set the stirring speed to 300r / min, raise the temperature to 110℃, and keep the reaction at this temperature for 1.5h. Cool down to 75℃, add 1.0g of catalyst Zn-Co DMC and 0.3g of antioxidant tea polyphenols, and continue stirring for 3.5h. After the reaction is completed, pour the polymer product into a polytetrafluoroethylene mold, place it in a constant temperature and humidity chamber, cure at room temperature for 24h, and demold to obtain the polyurethane sample of Comparative Example 2.

[0033] Performance comparison:

[0034] As can be seen from the above performance test data, the bio-based self-healing polyurethanes prepared in Examples 1 to 3 of this application all exhibit excellent comprehensive performance, with VOC emissions of only 0.2~0.3 mg / m³. 3 The first example exhibits outstanding environmental safety, achieving rapid self-repair within 1.8–2.5 hours at room temperature, with a self-healing efficiency of 95.1%–97.3%. The original tensile strength is 30.2–33.8 MPa, the tensile strength recovery rate remains at 91.7%–93.2%, and the strength retention rate after heat aging is as high as 94.8%–96.1%. In contrast, Comparative Example 1, without the addition of the zinc ion-tannic acid dynamic coordination crosslinking agent, showed a significantly prolonged room-temperature self-healing time to 24.0 hours, a self-healing efficiency of only 82.5%, a significantly decreased tensile strength to 19.2 MPa after healing, a tensile strength recovery rate of only 67.1%, and a strength retention rate after heat aging that also dropped to 90.2%. This indicates that the reversible dynamic network constructed by the dynamic coordination crosslinking agent is key to achieving rapid and efficient room-temperature self-healing and maintaining post-damage mechanical properties; the absence of this component leads to a significant deterioration in self-healing ability and mechanical stability. Comparative Example 2, which simply replaced the bio-based cyclic carbonate polyol with petroleum-based polyether polyol, saw its VOC emission increase to 1.5 mg / m³. 3The environmental friendliness is significantly reduced. The original tensile strength, the tensile strength after healing, and the strength retention rate after thermal aging are all lower than those of the embodiments of this application. Only the self-healing time and self-healing efficiency are close to those of Example 1, indicating that the self-healing performance is mainly determined by the dynamic coordination crosslinking agent. Bio-based cyclic carbonate polyol can significantly reduce the VOC release of the material, improve the mechanical strength and thermal aging stability, and achieve a balance between environmental friendliness, self-healing performance and mechanical properties in synergy with the dynamic coordination network. The overall effect is significantly better than the comparative example.

[0035] Although this application discloses preferred embodiments as described above, it is not intended to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.

Claims

1. A bio-based self-healing polyurethane, characterized in that, The raw materials, by weight, include: 40-60 parts of bio-based cyclic carbonate polyol, 20-30 parts of bio-based diamine, 5-10 parts of dynamic coordination crosslinking agent, 3-8 parts of chain extender, 0.5-2 parts of catalyst, and 0.1-0.5 parts of antioxidant; the dynamic coordination crosslinking agent is a complex formed by the coordination of zinc ions and tannic acid, and the molar ratio of zinc ions to tannic acid is 1:2 to 1:

3.

2. The bio-based self-healing polyurethane according to claim 1, characterized in that, The bio-based cyclic carbonate polyol is prepared by using castor oil as a starting material, followed by ring-opening polymerization of propylene oxide and then cycloaddition reaction with carbon dioxide; the hydroxyl value of the bio-based cyclic carbonate polyol is 180-220 mg KOH / g, and the bio-based content is not less than 85% by mass.

3. The bio-based self-healing polyurethane according to claim 1, characterized in that, The bio-based diamine is selected from bio-based decanediamine or lysine-based diamine; the bio-based content of the bio-based diamine is ≥98% by weight.

4. The bio-based self-healing polyurethane according to claim 1, characterized in that, The chain extender is selected from one or a mixture of two of 1,4-butanediol and bio-based 1,6-hexanediol.

5. The bio-based self-healing polyurethane according to claim 1, characterized in that, The catalyst is a bimetallic cyanide catalyst, and the active component of the bimetallic cyanide catalyst is selected from zinc-cobalt bimetallic cyanide or zinc-iron bimetallic cyanide.

6. The bio-based self-healing polyurethane according to claim 1, characterized in that, The antioxidant is selected from one or a mixture of at least two of the following: tea polyphenols, vitamin E, and beta-carotene.

7. A method for preparing a bio-based self-healing polyurethane, characterized in that, The preparation method includes: Castor oil is used as the starting material and mixed with propylene oxide at a mass ratio of 1:3 to 1:

5. A bimetallic cyanide catalyst is added, and polymerization is carried out at 120 to 140°C for 3 to 5 hours to obtain a polyether polyol. Carbon dioxide is introduced into the polyether polyol, and the reaction pressure is controlled at 0.5 to 1.0 MPa and the temperature at 80 to 100°C for 6 to 8 hours to obtain a bio-based cyclic carbonate polyol with a hydroxyl value of 180 to 220 mg KOH / g and a bio-based content of ≥85% by mass. Tannic acid was dissolved in deionized water to prepare a 5-10% (w / w) aqueous solution of tannic acid. A 0.5 mol / L zinc salt solution was slowly added dropwise to adjust the pH of the system to 6.5-7.

5. The reaction was carried out at 40-60℃ for 2-3 hours. After filtration and freeze-drying, a dynamic coordination crosslinking agent with a zinc ion to tannic acid molar ratio of 1:2 to 1:3 was obtained. By weight, 40-60 parts of bio-based cyclic carbonate polyol, 20-30 parts of bio-based diamine, 5-10 parts of dynamic coordination crosslinking agent, and 3-8 parts of chain extender are added to a reactor. Under nitrogen protection, the temperature is raised to 100-120°C and stirred for 1-2 hours. The temperature is then lowered to 70-80°C, and 0.5-2 parts of bimetallic cyanide catalyst and 0.1-0.5 parts of antioxidant are added. The reaction is continued to be stirred for 3-4 hours to obtain a polymer product. The polymer product is poured into a mold and cured at room temperature for 24 hours to obtain bio-based self-healing polyurethane.

8. The preparation method according to claim 7, characterized in that, The active component of the bimetallic cyanide catalyst is selected from zinc-cobalt bimetallic cyanide or zinc-iron bimetallic cyanide, and the amount of catalyst added is 0.1 to 0.3% of the total mass of castor oil and propylene oxide.

9. The preparation method according to claim 7, characterized in that, The zinc salt is selected from zinc chloride and zinc sulfate, and the dropping rate of the zinc salt solution is 1-3 mL / min.

10. Application of a bio-based self-healing polyurethane in flexible electronic device packaging and surface protective coating.

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