A self-repairing, reprocessable and degradable polyurethane material based on multiple bond effects and preparation method thereof

Abstract

The present invention discloses a self-repairing, reprocessable and degradable polyurethane material based on multiple bond effects and a preparation method thereof, which belongs to the field of self-repairing polyurethane materials. The polyurethane material of the present invention is prepared by heating and stirring a terminal hydroxyl polyether polyol and a diisocyanate under the action of a catalyst, then adding a diamine and heating and stirring, and finally adding hydroxyethyl hexahydro-s-triazine and stirring, and then pouring it into a polytetrafluoroethylene mold for curing. The self-repair efficiency of the tensile strength and elongation at break of the polyurethane prepared by the present invention can reach 98%, and after three cycles of reprocessing, the tensile strength is still as high as 36.6Mpa. The polyurethane material prepared by the present invention is completely degraded after being immersed in a 1moL / L phosphoric acid / ethanol solution for 1 hour, showing good degradability. Compared with traditional polyurethane materials, the polyurethane material prepared by the present invention has the advantages of self-repairing, reprocessability and degradability, and is a new sustainable material.

Description

Technical Field

[0001] The present invention relates to the field of self-repairing polyurethane materials, and in particular to a self-repairing, repeatedly processable and degradable polyurethane material based on multiple bond effects and a preparation method thereof. Background Art

[0002] Polyurethane (PU) materials are widely used in coatings, elastomers, flexible protective materials, and other fields due to their excellent properties, such as high elasticity, ease of synthesis, and chemical resistance. However, traditional materials are characterized by irreversible covalent bonds. Once broken, they are irreversible, making self-repair difficult and easily causing resource waste and environmental pollution.

[0003] In order to achieve self-repair of materials and restore their mechanical properties, researchers have endowed polyurethane with self-repairing properties by introducing reversible dynamic covalent bonds (Schiff base, disulfide bond, DA bond, borate bond, etc.) and non-covalent bonds (hydrogen bond, metal coordination bond, ionic bond, etc.). An et al. proposed the use of thioxo-β-diketone-Cu 2+ A synergistic strategy of metal ligand coordination (ML) and hydrogen bonding was used to prepare an elastomer (fracture strength 4.35 MPa, fracture strain 3400%). At the same time, the elastomer can achieve a high self-healing efficiency (94%). Song et al. developed a new supramolecular polyurethane elastomer by combining dynamic covalent borate and boron nitrogen (BN) coordination. The prepared material has high self-healing efficiency, but its mechanical strength is low.

[0004] The aforementioned research introduces reversible dynamic bonds or non-covalent bonds into the polymer structure, giving the material self-healing properties. Although it has reconstructive properties, it is susceptible to temperature effects, dissociating at high temperatures or undergoing chemical changes within the material, leading to degradation of mechanical properties and an inability to achieve both high self-healing efficiency and high mechanical strength. To overcome these problems, the present invention, based on the perspective of molecular structure design, develops a polyurethane material with a series of characteristics such as high mechanical strength, recyclability, self-healing, and biodegradability based on a synergistic strategy of dual reversible dynamic covalent bonds and non-covalent bonds, thereby achieving the sustainable development of polyurethane materials.

[0005] The disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of this application. Summary of the Invention

[0006] The purpose of the present invention is to propose a self-repairing, reprocessable and degradable polyurethane material and preparation method to solve the technical problems of the above-mentioned prior art that high repair efficiency and mechanical properties cannot be achieved at the same time, and the mechanical properties are degraded.

[0007] In order to solve the above technical problems, the present invention has the following technical solutions:

[0008] A self-repairable, reprocessable, and biodegradable polyurethane material based on dual dynamic covalent bonds and hydrogen bonds. Its polyurethane structure contains two reversible dynamic covalent bonds and multiple hydrogen bonds. Its strength and toughness can be controlled by the ratio of soft and hard segments. Its typical synthetic reaction structure features are as follows:

[0009]

[0010] The dynamic covalent bonds are disulfide bonds and hexahydrotriazine rings. The reversible exchange reaction characteristics of the disulfide bond structure endow the material with self-repairability and reprocessability, while the acid sensitivity of the hexahydrotriazine ring makes the material degradable.

[0011] A method for preparing a self-repairing, reprocessable and degradable polyurethane material based on dual dynamic covalent bonds and hydrogen bonds, comprising the following steps:

[0012] S1. Under a nitrogen atmosphere, weigh the hydroxyl-terminated polyether / polyester after vacuum drying and dehydration, heat it to 110-120°C, remove water in vacuum under stirring for 1-2 hours, then cool it to 80°C, add diisocyanate and catalyst dibutyltin dilaurate, continue the reaction for 2-3 hours, and prepolymerize under the action of the catalyst to obtain an -NCO-terminated polyurethane prepolymer; dissolve the chain extender 4,4-diaminodiphenyl sulfide in an organic solvent, add it to the reaction system to carry out a chain extension reaction, and the mixture obtained by the reaction is a polyurethane chain extension product based on a disulfide bond self-repairing structure;

[0013] S2. Continue to add hydroxyethyl hexahydro-s-triazine to the polymerization system of step S1 and continue the reaction for 45 minutes; then pour the reaction solution into a polytetrafluoroethylene mold for leveling, and place it in an oven to evaporate the solvent to obtain a self-repairable, reprocessable and degradable polyurethane material.

[0014] Furthermore, the hydroxyl-terminated polyether / polyester described in step S1 includes one or more of hydroxyl-terminated polyethylene glycol, polypropylene glycol, polybutylene glycol, polycaprolactone, and polybutylene succinate, and has a molecular weight of 500-3000.

[0015] Furthermore, the diisocyanate in step S1 includes one or more of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

[0016] Furthermore, the catalyst described in step S1 includes one or more of dibutyltin dilaurate, N,N-dimethylcyclohexylamine, and stannous isooctanoate, and the usage amount accounts for 0.05-0.1wt% of the total mass of the reactants.

[0017] Furthermore, in step S1, the group ratio of NCO:(OH+NH2) is (1.2-1.5):1.

[0018] Furthermore, the solvent in step S2 includes one or more of NN-dimethylformamide, tetrahydrofuran, dimethylene sulfoxide, and N-methylpyrrolidone.

[0019] Furthermore, the polyurethane prepared in step S1 and step S2 contains a carbamate structure and a urea group. The coexistence of these two structures enables hydrogen bonds to be formed within the polyurethane molecular chain and between molecules.

[0020] Furthermore, the preparation method of the self-repairable, reprocessable and degradable polyurethane material based on dual dynamic covalent bonds and hydrogen bonds is prepared under the conditions of heating and stirring the reaction at 80°C for 2-3 hours, and after curing, the self-repairable, reprocessable and degradable polyurethane material based on multiple bond effects is obtained.

[0021] Furthermore, the curing time is 24 hours.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The polyurethane elastomer of the present invention has a synergistic effect of dual reversible covalent bonds and hydrogen bonds, forming a physical cross-linked structure, improving the mechanical properties of the material, and the polyurethane elastomer can be quickly and completely degraded under weak acid conditions.

[0024] (2) The polyurethane elastomer of the present invention has excellent self-healing properties under certain temperature and time, and the synergistic effect of reversible dynamic covalent bonds and hydrogen bonds enables the elastomer to have both high mechanical strength and high repair efficiency.

[0025] (3) The polyurethane elastomer of the present invention can still maintain a high mechanical strength after multiple processing cycles, and the tensile strength after three cycles of processing is as high as 36.6 MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the structure of a polyurethane elastomer containing a hydrogen bond structure.

[0027] Figure 2 FTIR spectra of polyurethane elastomer under different NCO / (OH+NH2) and NH2:OH conditions.

[0028] Figure 3Microscope photos of the fracture surface of polyurethane elastomer before and after self-healing of scratches.

[0029] Figure 4 The stress-strain curve of the polyurethane elastomer at different time intervals after stretching.

[0030] Figure 5 This is the stress-strain curve of polyurethane elastomer under different repair times.

[0031] Figure 6 The stress-strain curves of polyurethane elastomers obtained with different processing cycles.

[0032] Figure 7 Digital image of polyurethane elastomer degradation in an acidic environment. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below with reference to specific embodiments and with reference to the accompanying drawings. It should be emphasized that the following description is merely illustrative and is not intended to limit the scope of the present invention and its application. The advantages and all changes that can be thought of by those skilled in the art of polymer self-healing materials are included in the present invention, and the present invention covers all modifications, substitutions, equivalent methods and schemes within the concept and scope of the present invention as defined by the claims. The preparation process, reaction conditions, reagents, experimental methods, etc. for implementing the present invention, except for the contents specifically involved below, are all common knowledge and common sense in the field, and the present invention has no specific limiting contents. In order for the public to better understand the present invention, some specific details are described in detail here. For those skilled in the art, the present invention can be fully understood without these details.

[0034] Non-limiting and non-exclusive embodiments will be described with reference to the following figures, wherein like reference numerals refer to like parts unless otherwise specifically specified.

[0035] Example 1

[0036] A method for preparing a self-repairable and degradable polyurethane with dual reversible dynamic covalent bonds and hydrogen bonds comprises the following steps:

[0037] (1) 4 g of hydroxyl-terminated polytetrahydrofuran (PTHF) with a molecular weight of 2000 and a mass of 2 mmol was placed in a three-necked flask with a stirrer, heated to 110°C, and vacuum-dried for 1 h while stirring. The mixture was then cooled to 80°C, and 1.34 g of isophorone diisocyanate (6 mmol) and a drop of dibutyltin dilaurate (DBTDL) were added, and the reaction was continued for 3 h to form a prepolymer.

[0038] (2) 0.31 g of 4-4'-diaminodiphenyl disulfide (1.25 mmol) was dissolved in 3 mL of DMF and added to the above prepolymer for chain extension reaction for 3 h. Then 0.19 g of hexahydro-1,3,5-tris(hydroxyethyl)-isotriazine (0.83 mmol) was dissolved in 3 mL of DMF and added to the above mixture solution and stirred evenly. After reacting for 45 min, the reaction solution was poured into a polytetrafluoroethylene mold and dried at 80 ° C for 48 h to obtain a self-repairing and degradable polyurethane elastomer with dual reversible dynamic covalent bonds and hydrogen bonds with NCO / (NH2+OH) of 1.2 and NH2 / OH of 1:1.

[0039] Example 2

[0040] A method for preparing a self-repairable and degradable polyurethane with dual reversible dynamic covalent bonds and hydrogen bonds comprises the following steps:

[0041] (1) 4 g of hydroxyl-terminated polytetrahydrofuran (PTHF) with a molecular weight of 2000 and a mass of 2 mmol was placed in a three-necked flask with a stirrer, heated to 110°C, and vacuum-dried for 1 h while stirring. The mixture was then cooled to 80°C, and 1.34 g of isophorone diisocyanate (6 mmol) and a drop of dibutyltin dilaurate (DBTDL) were added and the reaction continued for 3 h to form a prepolymer.

[0042] (2) 4-4'-diaminodiphenyl disulfide (0.31 g, 1.25 mmol) was dissolved in 3 mL of DMF and added to the above prepolymer for chain extension reaction for 3 h. Then, 0.19 g of hexahydro-1,3,5-tris(hydroxyethyl)-s-triazine (0.83 mmol) was dissolved in 3 mL of DMF and added to the above mixture solution and stirred evenly. After reacting for 45 min, the reaction solution was poured into a polytetrafluoroethylene mold and dried at 80 ° C for 48 h to obtain a self-repairing and degradable polyurethane elastomer with dual reversible dynamic covalent bonds and hydrogen bonds with NCO / (NH2+OH) of 1.3 and NH2 / OH of 1:1.

[0043] Example 3

[0044] A method for preparing a self-repairable and degradable polyurethane with dual reversible dynamic covalent bonds and hydrogen bonds comprises the following steps:

[0045] (1) 4 g of hydroxyl-terminated polytetrahydrofuran (PTHF) with a molecular weight of 2000 and a mass of 2 mmol was placed in a three-necked flask with a stirrer, heated to 110°C, and vacuum-dried for 1 h while stirring. The mixture was then cooled to 80°C, and 1.41 g of isophorone diisocyanate (6.3 mmol) and a drop of dibutyltin dilaurate (DBTDL) were added and the reaction continued for 3 h to form a prepolymer.

[0046] (2) 0.31 g of 4-4'-diaminodiphenyl disulfide (1.25 mmol) was dissolved in 3 mL of DMF and added to the above prepolymer for chain extension reaction for 3 h. Then 0.19 g of hexahydro-1,3,5-tris(hydroxyethyl)-isotriazine (0.83 mmol) was dissolved in 3 mL of DMF and added to the above mixture solution and stirred evenly. After reacting for 45 min, the reaction solution was poured into a polytetrafluoroethylene mold and dried at 80 ° C for 48 h to obtain a self-repairing and degradable polyurethane elastomer with dual reversible dynamic covalent bonds and hydrogen bonds with NCO / (NH2+OH) of 1.4 and NH2 / OH of 1:1.

[0047] Example 4

[0048] A method for preparing a self-repairable and degradable polyurethane with dual reversible dynamic covalent bonds and hydrogen bonds comprises the following steps:

[0049] (1) 4 g of hydroxyl-terminated polytetrahydrofuran (PTHF) with a molecular weight of 2000 and a mass of 2 mmol was placed in a three-necked flask with a stirrer, heated to 110°C, and vacuum-dried for 1 h while stirring. The mixture was then cooled to 80°C, and 1.51 g of isophorone diisocyanate (6.75 mmol) and a drop of dibutyltin dilaurate (DBTDL) were added and the reaction continued for 3 h to form a prepolymer.

[0050] (2) 0.31 g of 4-4'-diaminodiphenyl disulfide (1.25 mmol) was dissolved in 3 mL of DMF and added to the above prepolymer for chain extension reaction for 3 h. Then 0.19 g of hexahydro-1,3,5-tris(hydroxyethyl)-isotriazine (0.83 mmol) was dissolved in 3 mL of DMF and added to the above mixture solution and stirred evenly. After reacting for 45 min, the reaction solution was poured into a polytetrafluoroethylene mold and dried at 80 ° C for 48 h to obtain a self-repairing and degradable polyurethane elastomer with dual reversible dynamic covalent bonds and hydrogen bonds with NCO / (NH2+OH) of 1.5 and NH2 / OH of 1:1.

[0051] Example 5

[0052] A method for preparing a self-repairable and degradable polyurethane with dual reversible dynamic covalent bonds and hydrogen bonds comprises the following steps:

[0053] (1) 4 g of hydroxyl-terminated polytetrahydrofuran (PTHF) with a molecular weight of 2000 and a mass of 2 mmol was placed in a three-necked flask with a stirrer, heated to 110°C, and vacuum-dried for 1 h while stirring. The mixture was then cooled to 80°C, and 1.34 g of isophorone diisocyanate (6 mmol) and a drop of dibutyltin dilaurate (DBTDL) were added and the reaction continued for 3 h to form a prepolymer.

[0054] (2) 0.25 g of 1 mmol of 4-4'-diaminodiphenyl disulfide was dissolved in 3 mL of DMF and added to the above prepolymer for chain extension reaction for 3 hours. Then, 0.22 g of 1 mmol of hexahydro-1,3,5-tris(hydroxyethyl)-isotriazine was dissolved in 3 mL of DMF and added to the above mixture solution and stirred evenly. After reacting for 45 minutes, the reaction solution was poured into a polytetrafluoroethylene mold and dried at 80°C for 48 hours to obtain a self-repairing and degradable polyurethane elastomer with dual reversible dynamic covalent bonds and hydrogen bonds with NCO / (NH2+OH) of 1.3 and NH2 / OH of 2:3.

[0055] Example 6

[0056] A method for preparing a self-repairable and degradable polyurethane with dual reversible dynamic covalent bonds and hydrogen bonds comprises the following steps:

[0057] (1) 4 g of hydroxyl-terminated polytetrahydrofuran (PTHF) with a molecular weight of 2000 and a mass of 2 mmol was placed in a three-necked flask with a stirrer, heated to 110°C, and vacuum-dried for 1 h while stirring. The mixture was then cooled to 80°C, and 1.34 g of isophorone diisocyanate (6 mmol) and a drop of dibutyltin dilaurate (DBTDL) were added and the reaction continued for 3 h to form a prepolymer.

[0058] (2) 0.37 g of 4-4'-diaminodiphenyl disulfide (1.5 mmol) was dissolved in 3 mL of DMF and added to the above prepolymer for chain extension reaction for 3 h. Then 0.15 g of hexahydro-1,3,5-tris(hydroxyethyl)-isotriazine (0.67 mmol) was dissolved in 3 mL of DMF and added to the above mixture solution and stirred evenly. After reacting for 45 min, the reaction solution was poured into a polytetrafluoroethylene mold and dried at 80 ° C for 48 h to obtain a self-repairing and degradable polyurethane elastomer with dual reversible dynamic covalent bonds and hydrogen bonds with NCO / (NH2+OH) of 1.3 and NH2 / OH of 3:2.

[0059] Example 7

[0060] A method for preparing a self-repairable and degradable polyurethane with dual reversible dynamic covalent bonds and hydrogen bonds comprises the following steps:

[0061] (1) 4 g of hydroxyl-terminated polycaprolactone with a molecular weight of 2000 and a mass of 2 mmol was placed in a three-necked flask with a stirrer, heated to 110°C, and the water was removed in vacuo under stirring for 1 hour. The mixture was then cooled to 80°C, and 1.34 g of isophorone diisocyanate with a mass of 6 mmol and a drop of dibutyltin dilaurate (DBTDL) were added and the reaction was continued for 3 hours to form a prepolymer.

[0062] (2) 0.37 g of 4-4'-diaminodiphenyl disulfide (1.5 mmol) was dissolved in 3 mL of DMF and added to the above prepolymer for chain extension reaction for 3 h. Then 0.15 g of hexahydro-1,3,5-tris(hydroxyethyl)-isotriazine (0.67 mmol) was dissolved in 3 mL of DMF and added to the above mixture solution and stirred evenly. After reacting for 45 min, the reaction solution was poured into a polytetrafluoroethylene mold and dried at 80 ° C for 48 h to obtain a self-repairing and degradable polyurethane elastomer with dual reversible dynamic covalent bonds and hydrogen bonds with NCO / (NH2+OH) of 1.3 and NH2 / OH of 1:1.

[0063] See Figure 1 The polyurethane elastomers prepared in Examples 1-6 contain dual reversible dynamic covalent bonds and hydrogen bonds, which form physical crosslinking points through the thermally reversible exchange of disulfide bonds and the multiple hydrogen bonds between urea bonds and carbamate bonds in the structure. The synergistic effect of the two further promotes the microphase separation of the polyurethane elastomer, so that the elastomer has high tensile strength, high toughness and high resilience. In addition, since the structure contains acid-sensitive hexahydrotriazine rings, the elastomer can be quickly and completely degraded in a weak acid environment. Due to the reversible properties of reversible covalent bonds and hydrogen bonds, the elastomer has excellent self-healing and processability. The presence of hydrogen bonds is conducive to the rapid repair of the elastomer, and the combined action of hydrogen bonds and reversible covalent bonds is conducive to deep repair of the elastomer. The self-healing, strength and toughness of the elastomer can be adjusted by adjusting the ratio of soft and hard segments in the polyurethane structure.

[0064] See Figure 2 , the different NCO / (OH+NH2) and NH2:OH of PU elastomer were characterized by ATR-FTIR. -1 and 1542cm -1 The absorption peaks at 2937cm- -1 and 2854cm -1The absorption peaks at 1703 cm-1 are the symmetric and antisymmetric stretching vibration peaks of CH. In addition, the stretching vibration peak of C=O in carbamate is located at 1703 cm-1. -1 Nearby, at 1454cm -1 and 1366cm -1 The bending vibration of -CH2- can also be observed at 2260cm -1 No characteristic peak of -NCO was found at , indicating that the remaining -NCO had completely reacted with hydroxyethylhexahydro-s-triazine.

[0065] See Figure 3 After obvious scratches were made on the surface of the polyurethane elastomer prepared in Example 5 with a blade, it was initially healed and then self-healed at 100°C. Through microscopic observation, the scratches disappeared, indicating its excellent self-healing performance.

[0066] See Figure 4 The stress-strain curve of the second stretching after 5 minutes is significantly lower than that of the first stretching. Although the strength when stretched to a strain of 200% increases with the extension of the interval time, the strength of the second stretching after 30 minutes has not fully recovered. This is because some hydrogen bonds have been damaged and broken during the first stretching, and the repair time is not enough for a large number of hydrogen bonds to reorganize. Figure 3 It can be seen that when the second stretching is performed 12 hours after the first, the stress-strain curve almost overlaps with the first stretching curve. The table above further demonstrates that the strength at 200% strain after a 12-hour interval is higher than the strength after 30 minutes. Furthermore, a longer interval promotes the recovery of the elastomer's strength. The tensile strength recovery rate after a 12-hour interval is as high as 99.7%. Therefore, the reorganization of hydrogen bonds after rupture is a key factor in the recovery of the mechanical properties of elastomers.

[0067] See Figure 5 The polyurethane elastomer strip prepared in Example 5 was cut in the middle, and the fracture surfaces were connected together to quickly achieve preliminary healing at room temperature. It was then repaired under heating conditions at 100°C. As time went on, the repair efficiency gradually increased. The tensile strength of the original polyurethane sample was 46.4 MPa, and the elongation at break was 932.6%. The repair efficiency of the polyurethane elastomer at 100°C for 4 hours, 8 hours, 12 hours, 18 hours, and 24 hours reached 17%, 48%, 61%, 76%, and 98%, respectively. After repairing at 100°C for 24 hours, the tensile strength could reach 45.7 MPa. As the repair time was extended from 4 hours to 24 hours, the molecular chains had more time to diffuse into the damaged area during the longer repair time, which was conducive to the reorganization of the dissociated disulfide bonds and hydrogen bonds, thereby increasing the repair efficiency of the elastomer over time.

[0068] See Figure 6Utilizing the reversible nature of the dynamic network of disulfide and hydrogen bonds, the resulting elastomer can be recycled and reused using traditional polymer preparation methods. The hot-pressing recycling method involves cutting the film into pieces and laying them flat together. The two layers are then sandwiched between a stainless steel mold plate and hot-pressed at 0.5 MPa and 100°C for one hour. Finally, the plate cools to produce a flat film. While the tensile strength and elongation at break decrease after recycling, the tensile strength and elongation at break remain as high as 36.6 MPa and 871%, respectively, after the third recycling step.

[0069] See Figure 7 Four polyurethane elastomer films with different proportions were placed in 1 mol / L phosphoric acid-ethanol solution for degradation experiments, and it was found that they could all be quickly and completely degraded at room temperature.

[0070] The above content is a further detailed description of the present invention in conjunction with specific implementation methods, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, they can make several substitutions or modifications to the described embodiments without departing from the concept of the present invention, and these substitutions or modifications should be considered to fall within the scope of protection of the present invention.

Claims

1. A self-repairable, reprocessable and degradable polyurethane material based on dual dynamic covalent bonds and hydrogen bonds, characterized by: The polyurethane structure is based on two reversible dynamic covalent bonds and multiple hydrogen bonds; its strength and toughness are controlled by the ratio of soft and hard segments. The structural diagram of its synthesis reaction process is as follows: 。 2. A method for preparing a self-repairing, reprocessable and degradable polyurethane material based on dual dynamic covalent bonds and hydrogen bonds, characterized by: The following steps are involved: (1) Under a nitrogen atmosphere, a hydroxyl-terminated polyether / polyester after vacuum drying and dehydration is weighed, a diisocyanate is added, and prepolymerization is carried out under the action of a catalyst to obtain an -NCO-terminated polyurethane prepolymer; a chain extender 4,4-diaminodiphenyl sulfide is dissolved in an organic solvent and added to the reaction system to carry out a chain extension reaction. The resulting mixture is a polyurethane chain extension product based on a disulfide bond self-repairing structure; (2) Hydroxyethyl hexahydrotriazine is continued to be added to the polymerization system in step (1) to continue the reaction. The reaction liquid is then poured into a polytetrafluoroethylene mold for leveling and placed in an oven to evaporate the solvent, thereby obtaining a self-repairable, reprocessable and degradable polyurethane material.

3. The method for preparing a self-repairable, reprocessable and degradable polyurethane material based on dual dynamic covalent bonds and hydrogen bonds according to claim 2, characterized in that: The hydroxyl-terminated polyether / polyester described in step (1) includes one or more of hydroxyl-terminated polyethylene glycol, polypropylene glycol, polybutylene glycol, polycaprolactone, and polybutylene succinate.

4. The method for preparing a self-repairing, reprocessable and degradable polyurethane material based on dual dynamic covalent bonds and hydrogen bonds according to claim 2, characterized in that: The diisocyanate described in step (1) includes one or more of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

5. The method for preparing a self-repairable, reprocessable and degradable polyurethane material based on dual dynamic covalent bonds and hydrogen bonds according to claim 2, characterized in that: The catalyst described in step (1) includes one or more of dibutyltin dilaurate, N,N-dimethylcyclohexylamine, and stannous isooctanoate, and the amount used accounts for 0.05-0.1 wt% of the total mass of the reactants.

6. The method for preparing a self-repairable, reprocessable and degradable polyurethane material based on dual dynamic covalent bonds and hydrogen bonds according to claim 2, characterized in that: The group ratio of NCO:(OH+NH2) in step (1) is (1.2-1.5):

1.

7. The method for preparing a self-repairable, reprocessable and degradable polyurethane material based on dual dynamic covalent bonds and hydrogen bonds according to claim 2, characterized in that: The reaction time in step (2) is 45 min.

8. The method for preparing a self-repairing, reprocessable and degradable polyurethane material based on dual dynamic covalent bonds and hydrogen bonds according to claim 2, characterized in that: The solvent in step (2) includes one or more of NN-dimethylformamide, tetrahydrofuran, dimethylene sulfoxide, and N-methylpyrrolidone.

9. The method for preparing a self-repairable, reprocessable and degradable polyurethane material based on dual dynamic covalent bonds and hydrogen bonds according to any one of claims 2 to 8, characterized in that: The preparation conditions are heating and stirring at 80 ° C for 2-3 hours. After curing, a self-repairing, reprocessable and degradable polyurethane material based on multiple bond effects is obtained.

10. The method for preparing a self-repairable, reprocessable and degradable polyurethane material based on dual dynamic covalent bonds and hydrogen bonds according to claim 9, characterized in that: The curing time is 24h.

Images