A flexible polyvinyl alcohol-polyurethane sponge and its preparation method and application

Abstract

A flexible polyvinyl alcohol-polyurethane sponge and its preparation method and application relate to the technical field of polyvinyl alcohol sponges, and solve the problem that the mechanical properties and safety performance of existing polyvinyl alcohol-polyurethane sponges are insufficient. In the present invention, polyethylene glycol and hexamethylene diisocyanate are reacted to obtain an isocyanate-terminated polyurethane prepolymer, which is further reacted with a hydrophilic chain extender dimethylolpropionic acid and a hydroxyl-containing acrylate to prepare a vinyl-functionalized polyurethane and make it into a polyurethane aqueous solution; the polyvinyl alcohol aqueous solution is mixed with the polyurethane aqueous solution, and after being treated by steps such as irradiation and freeze-drying, a flexible polyvinyl alcohol-polyurethane sponge is prepared. The polyvinyl alcohol-polyurethane sponge provided by the present invention has a dense three-dimensional cross-linked network structure, good flexibility, adjustable mechanical properties, high water absorption, and at the same time ensures its application safety in the fields of biomedicine and tissue engineering, meeting the development requirements of green materials.

Description

Technical Field

[0001] The present invention relates to the technical field of polyvinyl alcohol sponges, and particularly to a flexible polyvinyl alcohol-polyurethane sponge, a preparation method thereof, and an application thereof. Background Art

[0002] As an important type of functional material, sponge materials have been widely used in many fields such as industry, civil use, and medical treatment. Among them, polyvinyl alcohol sponge is a high-porosity foam material made by a foaming process, which has excellent water absorption, moisture absorption, and biocompatibility, and is widely used in medical dressings, environmental water treatment, packaging materials, etc. However, polyvinyl alcohol sponge is prone to water loss, resulting in poor flexibility, and may cause secondary trauma to patients when applied in the medical field. Moreover, the material is prone to rupture or deformation when under great pressure or used for a long time. Polyurethane sponge is a high-elastic, porous structure material made by a polyurethane foaming reaction, which has excellent elasticity and softness, can withstand multiple compressions and deformations and quickly return to its original state, and is widely used in furniture, automobiles, buildings, packaging, and medical fields. However, the long-term stability and environmental friendliness of polyurethane sponge need to be improved.

[0003] Currently, some researchers have tried to combine polyvinyl alcohol sponge and polyurethane sponge to prepare polyvinyl alcohol-polyurethane sponge to overcome the defects of polyvinyl alcohol sponge and polyurethane sponge when used alone. For example, Chinese Patent Document CN102827442A discloses a preparation method of a polyvinyl alcohol-polyurethane highly water-absorbent sponge, which uses cross-linking and curing of polyvinyl alcohol and polyurethane prepolymer, and improves its stability and mechanical properties by physical blending and foaming. However, this method involves the use of a toxic organotin catalyst, which has potential risks in the application in the medical field. Chinese Patent Document CN112063008A discloses a water-soluble sponge with a density gradient, a preparation method thereof, and an application thereof, which uses a blend of polyurethane and polyvinyl alcohol aqueous solution, centrifugation, and freeze-drying to prepare a water-soluble sponge with a density gradient for use as a hemostatic material. However, the mechanical properties of the water-soluble sponge prepared by this invention still need to be improved to provide sufficient structural support and load-bearing capacity in practical applications.

[0004] In summary, it is of great significance to develop a flexible polyvinyl alcohol-polyurethane sponge with excellent mechanical properties and safety performance to further broaden the application fields of sponge materials and promote the innovative development of materials science and green technology. Summary of the Invention

[0005] In order to solve the problem that the mechanical properties and safety performance of the existing polyvinyl alcohol-polyurethane sponge are insufficient, the present invention provides a flexible polyvinyl alcohol-polyurethane sponge, a preparation method thereof, and an application thereof.

[0006] A preparation method of a flexible polyvinyl alcohol-polyurethane sponge, comprising the following steps:

[0007] S1: Mix polyethylene glycol (PEG) and hexamethylene diisocyanate (HDI), and stir to make them react to obtain an isocyanate-terminated polyurethane prepolymer;

[0008] S2: Add the hydrophilic chain extender dimethylolpropionic acid (DMPA) to the isocyanate-terminated polyurethane prepolymer for reaction. After the reaction is completed, lower the temperature of the reaction system, continue to add a hydroxyl-containing acrylate for reaction, and finally add triethylamine (TEA) for neutralization reaction to prepare a vinyl-functionalized polyurethane. Disperse the vinyl-functionalized polyurethane into a polyurethane aqueous solution;

[0009] S3: Mix the polyvinyl alcohol aqueous solution with the polyurethane aqueous solution prepared in S2, carry out irradiation, then carry out freeze molding, and finally carry out freeze drying to prepare a flexible polyvinyl alcohol-polyurethane sponge;

[0010] Further, the mass ratio of the polyethylene glycol and hexamethylene diisocyanate (HDI) in S1 is 1:2 - 3;

[0011] Further, the stirring temperature in S1 is 80 - 95 °C, and the stirring time is 1 - 3 h;

[0012] Further, the molecular weight of the polyethylene glycol in S1 is 500 - 5000;

[0013] Further, the hydrophilic chain extender in S2 is dimethylolpropionic acid;

[0014] Further, the molar ratio of -OH in the dimethylolpropionic acid to -NCO in the isocyanate-terminated polyurethane prepolymer in S2 is 0.1 - 0.9:1;

[0015] Further, the temperature for adding dimethylolpropionic acid for reaction in S2 is 80 - 90 °C, the reaction time is 0.5 - 2 h, and after the reaction is completed, the temperature of the reaction system is lowered to 40 - 60 °C;

[0016] Further, the molar ratio of -OH in the hydroxyl-containing acrylate to -NCO in the isocyanate-terminated polyurethane prepolymer in S2 is 0.1 - 0.9:1;

[0017] Further, the reaction time for adding the hydroxyl-containing acrylate in S2 is 3 h;

[0018] Further, the hydroxyl-containing acrylate in S2 is selected from any one of hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), hydroxyethyl methacrylate (HEMA), or pentaerythritol triacrylate (PETA);

[0019] Further, the solid content of the polyurethane aqueous solution in S2 is 5-10%;

[0020] Further, the volume ratio of the polyvinyl alcohol aqueous solution to the polyurethane aqueous solution in S3 is 1-10:1;

[0021] Further, the irradiation dose in S3 is 5-50 kGy;

[0022] Further, the irradiation light in S3 is selected from any one of a high-energy electron accelerator, a cobalt source, X-rays or ultraviolet light; [[ID=...]]

[0023] Further, the freeze-forming temperature in S3 is -30~-15°C; the freeze-forming time is 6~24 h;

[0024] Further, the freeze-drying time in S3 is 24~48 h.

[0025] A flexible polyvinyl alcohol-polyurethane sponge is prepared by the above preparation method.

[0026] A flexible polyvinyl alcohol-polyurethane sponge is applied to the fields of biomedicine and tissue engineering.

[0027] Compared with the prior art, the present invention solves the problem that the mechanical properties and safety properties of the flexible polyvinyl alcohol-polyurethane sponge are insufficient, and the specific beneficial effects are as follows:

[0028] 1. Formation of a three-dimensional cross-linked network structure with high cross-linking density: The present invention uses the -OH in the hydroxy-containing acrylate to perform a nucleophilic addition reaction with the -NCO in the isocyanate-terminated polyurethane prepolymer, and then introduces the C=C group with radiation cross-linking sensitization effect into the polyurethane structure to prepare vinyl-functionalized polyurethane; The polyvinyl alcohol-polyurethane sponge is prepared by the irradiation cross-linking method. During the irradiation process, polyvinyl alcohol and polyurethane absorb energy, resulting in the breakage of some covalent bonds and the generation of free radicals, and these free radicals carry out cross-linking reactions. The introduction of C=C in polyurethane, the electron cloud density of its π bond is relatively high, and it is easy to be attacked by electrophilic reagents, and the sensitivity of the polymer to radiation cross-linking can be enhanced through an addition reaction. By cross-linking with the reactive groups (such as hydroxyl groups, amino groups, etc.) in polyvinyl alcohol and polyurethane, a dense three-dimensional cross-linked network structure is formed.

[0029] 2. Excellent mechanical properties: By regulating the irradiation dose and the content of carbon-carbon double bonds (C=C), the present invention effectively adjusts the internal cross-linking degree of the polyvinyl alcohol-polyurethane sponge. With the increase in the introduced amount of C=C, the internal cross-linking reaction of the polyvinyl alcohol-polyurethane sponge is further promoted, the network structure of the polymer is enhanced, the mobility of the polymer chains is restricted, making the pore structure of the sponge more compact and uniform, thereby greatly improving the mechanical properties of the polyvinyl alcohol-polyurethane sponge. In addition, with the increase in the irradiation dose, the cross-linking effect of C=C and the free radicals generated by radiation act synergistically to promote the linking and twisting rearrangement of the polyurethane segments, thereby endowing the polyvinyl alcohol-polyurethane sponge with excellent flexibility and ductility.

[0030] 3. Safe and environmentally friendly: The present invention prepares the polyvinyl alcohol-polyurethane sponge by using the irradiation cross-linking method. The preparation process does not rely on chemical catalysts, avoiding the residue of harmful substances, ensuring the non-toxic and environmentally friendly characteristics of the material, successfully avoiding the problem of using toxic catalysts in traditional preparation methods, and significantly improving the application safety of the polyvinyl alcohol-polyurethane sponge in the medical field. At the same time, polyvinyl alcohol itself has good biocompatibility and biodegradability, which not only improves the mechanical properties and stability of the sponge material, but also makes it more suitable for fields with strict requirements for safety and environmental protection, such as biomedical and tissue engineering fields, meeting the development needs of green materials. Brief Description of the Drawings

[0031] Figure 1 is the synthesis route diagram of vinyl-functionalized polyurethane;

[0032] Figure 2 is the mechanism diagram of the sensitized cross-linking reaction. Detailed Embodiments

[0033] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the specification drawings of the present invention. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as a limitation of the present invention.

[0034] Example 1.

[0035] S1: Add 10.0 g of PEG with a molecular weight of 1000 and 3.4 g of HDI into a reaction flask, and react at 90 °C for 2 h to prepare an isocyanate-terminated polyurethane prepolymer;

[0036] S2: Add 0.7 g of DMPA to the isocyanate-terminated polyurethane prepolymer, react at 90 °C for 1.5 h. After the reaction is completed, lower the temperature of the reaction system to 50 °C, continue to add 1.2 g of HEA and react for 3 h. Finally, add 0.4 g of TEA for neutralization reaction to prepare vinyl-functionalized polyurethane. Disperse the vinyl-functionalized polyurethane into a polyurethane aqueous solution with a solid content of 10%.

[0037] S3: Weigh 10 g of polyvinyl alcohol solid and add it to 90 g of water. Gradually heat to 90 °C and continuously stir for 2 h until it is completely dissolved to obtain a 10% polyvinyl alcohol aqueous solution. Mix the polyvinyl alcohol aqueous solution and the polyurethane aqueous solution prepared in S2 according to a volume ratio of 1:1. Pour the mixed solution into a mold with a size of 10×10 cm, control the thickness of the solution to be 5 mm, and perform electron beam irradiation on the mixed solution at a dose of 30 kGy. After the irradiation is completed, place the mixed solution in an environment of -20 °C and freeze it for 12 h to form. After taking it out, perform freeze-drying for 24 h to prepare a flexible polyvinyl alcohol-polyurethane sponge.

[0038] As Figure 1 is the synthesis route diagram of vinyl-functionalized polyurethane. In the figure, OCN-R1-NCO is a diisocyanate, HO-R2-OH is a chain extender, R3-OH is a hydroxy-containing acrylate, where R1 and R2 are hydrocarbon groups with C3~C12 respectively, R3 is a hydrocarbon group with one or more terminal double bond structures, and n is a natural number from 3 to 12; in the synthesis process, in the present invention, through the addition reaction between -OH in the hydroxy-containing acrylate and -NCO in the diisocyanate, the C=C group with radiation cross-linking sensitization effect is introduced into the polyurethane structure to prepare vinyl-functionalized polyurethane, as Figure 2 is the sensitization cross-linking reaction mechanism diagram.

[0039] Example 2:

[0040] The difference between this example and Example 1 is that the volume ratio of the polyvinyl alcohol aqueous solution and the polyurethane aqueous solution blended in S3 is 9:1, and the remaining preparation steps and conditions are the same as those in Example 1.

[0041] Example 3:

[0042] The difference between this example and Example 1 is that the dose of electron beam irradiation on the mixed solution in S3 is 20 kGy.

[0043] Example 4:

[0044] S1: Add 10.0 g of PEG with a molecular weight of 1000 and 3.5 g of HDI to a reaction flask, and react at 90 °C for 2 h to prepare an isocyanate-terminated polyurethane prepolymer.

[0045] S2: Add 0.9 g of DMPA to the isocyanate-terminated polyurethane prepolymer, react at 85 °C for 1 h. After the reaction is completed, lower the temperature of the reaction system to 50 °C, continue to add 0.7 g of HEA and react for 3 h. Finally, add 0.6 g of TEA for neutralization reaction to prepare vinyl-functionalized polyurethane. Disperse the vinyl-functionalized polyurethane into a polyurethane aqueous solution with a solid content of 10%.

[0046] S3: Weigh 10 g of polyvinyl alcohol solid and add it to 90 g of water. Gradually heat to 90 °C and continuously stir for 2 h until it is completely dissolved to obtain a 10% (mass fraction) polyvinyl alcohol aqueous solution. Mix the polyvinyl alcohol aqueous solution and the polyurethane aqueous solution prepared in S2 according to a volume ratio of 1:1. Control the solution thickness to be 5 mm, and irradiate the mixed solution with an electron beam at a dose of 30 kGy. After the irradiation is completed, place the mixed solution in an environment at -20 °C and freeze for 12 h to form. Take it out and perform freeze-drying for 24 h to prepare a flexible polyvinyl alcohol-polyurethane sponge.

[0047] Example 5:

[0048] S1: Add 10.0 g of PEG with a molecular weight of 1000 and 3.7 g of HDI to a reaction flask, and react at 90 °C for 2 h to prepare an isocyanate-terminated polyurethane prepolymer.

[0049] S2: Add 0.7 g of DMPA to the isocyanate-terminated polyurethane prepolymer, react at 90 °C for 1 h. After the reaction is completed, lower the temperature of the reaction system to 60 °C, continue to add 3.0 g of PETA and react for 3 h. Finally, add 0.4 g of TEA for neutralization reaction to prepare vinyl-functionalized polyurethane. Disperse the vinyl-functionalized polyurethane into a polyurethane aqueous solution with a solid content of 10%.

[0050] S3: Weigh 10 g of polyvinyl alcohol solid and add it to 90 g of water. Gradually heat to 90 °C and continuously stir for 2 h until it is completely dissolved to obtain a 10% (mass fraction) polyvinyl alcohol aqueous solution. Mix the polyvinyl alcohol aqueous solution and the polyurethane aqueous solution prepared in S2 according to a volume ratio of 1:1. Pour the mixed solution into a mold with a size of 10×10 cm, control the solution thickness to be 5 mm, and irradiate the mixed solution with an electron beam at a dose of 30 kGy. After the irradiation is completed, place the mixed solution in an environment at -20 °C and freeze for 12 h to form. Take it out and perform freeze-drying for 24 h to prepare a flexible polyvinyl alcohol-polyurethane sponge.

[0051] Comparative Example 1:

[0052] S1: Add 10.0 g of PEG with a molecular weight of 1000 and 3.4 g of HDI into a reaction flask, and react at 90 °C for 2 h to prepare an isocyanate-terminated polyurethane prepolymer;

[0053] S2: Add 0.7 g of DMPA to the isocyanate-terminated polyurethane prepolymer, react at 90 °C for 1.5 h. After the reaction is completed, lower the temperature of the reaction system to 50 °C, continue to add 1.2 g of HEA and react for 3 h, and finally add 0.4 g of TEA for neutralization reaction to prepare vinyl-functionalized polyurethane. Disperse the vinyl-functionalized polyurethane into a polyurethane aqueous solution with a solid content of 10%;

[0054] S3: Mix the polyurethane aqueous solution prepared in S2 and water according to a volume ratio of 1:1. Pour the mixed solution into a mold with a size of 10×10 cm, control the thickness of the solution to be 5 mm, and perform electron beam irradiation on the mixed solution at a dose of 30 kGy. After the irradiation is completed, place the mixed solution in an environment of -20 °C and freeze it for 12 h to form. After taking it out, perform freeze-drying for 24 h to prepare a polyurethane sponge.

[0055] Comparative Example 2:

[0056] Weigh 10 g of polyvinyl alcohol solid and add it to 90 g of water. Gradually heat it to 90 °C and continuously stir for 2 h until it is completely dissolved to obtain a 10% polyvinyl alcohol aqueous solution; Mix the polyvinyl alcohol aqueous solution and water according to a volume ratio of 1:1. Pour the mixed solution into a mold with a size of 10×10 cm, control the thickness of the solution to be 5 mm, and perform electron beam irradiation on the mixed solution at a dose of 30 kGy. After the irradiation is completed, place the mixed solution in an environment of -20 °C and freeze it for 12 h to form. After taking it out, perform freeze-drying for 24 h to prepare a polyvinyl alcohol sponge.

[0057] Tensile property test:

[0058] According to GB / T 6344-2008, cut the samples prepared in Examples 1-5 and Comparative Examples 1-2 into dumbbell shapes and perform tensile property tests under a testing machine. The tensile speed is set at 50 mm / min.

[0059] Water absorption property test:

[0060] Weigh the samples prepared in Examples 1-5 and Comparative Examples 1-2 after drying and record as m1. Then completely immerse the samples in deionized water, take them out after soaking for 1 h, and weigh the samples again and record as m2. Calculate the water absorption rate according to the following formula:

[0061] Water absorption rate = (m2 - m1) / m1 * 100%.

[0062] The following table shows the performance results of the flexible polyvinyl alcohol-polyurethane sponges prepared in Examples 1-5, the polyurethane sponge prepared in Comparative Example 1, and the polyvinyl alcohol sponge prepared in Comparative Example 2. From the data in the table, it can be seen that the flexible polyvinyl alcohol-polyurethane sponges prepared in Examples 1-5 retain the excellent elongation at break of the polyurethane sponge and at the same time retain the excellent tensile strength of the polyvinyl alcohol sponge, improving the deficiency of the pure polyurethane sponge in terms of tensile strength and the deficiency of the pure polyvinyl alcohol sponge in terms of elongation at break. This is mainly because the hydroxyl-containing acrylate structure added in Examples 1-5 contains -OH and C=C double bonds. Through the nucleophilic addition reaction of -OH with the unreacted -NCO after chain extension, C=C double bonds are successfully introduced into the polyurethane structure. During the irradiation process, polyvinyl alcohol and polyurethane absorb energy, resulting in the breakage of some covalent bonds to generate free radicals, and crosslinking reactions occur between these free radicals to form a dense network structure, optimizing the mechanical properties.

[0063] From the results of Example 1 and Example 2, it can be seen that by changing the volume ratio of polyvinyl alcohol and polyurethane, due to the too high content of polyvinyl alcohol, the overall tensile strength of the material increases slightly, but the flexibility decreases significantly. This is because the content of polyurethane decreases, and an effective flexible phase cannot be formed. At the same time, the hydrogen bond interaction between polyvinyl alcohols increases, making the molecular chains difficult to slip and restricting the ductility of the material. From the results of Example 1 and Example 3 in the table, it can be seen that with the increase of the irradiation dose, the crosslinking effect of C=C and the free radicals generated by radiation act synergistically to promote the linking and twisting rearrangement of the polyurethane segments, thereby endowing the polyvinyl alcohol-polyurethane sponge with excellent tensile strength. From the results of Example 1 and Example 4, it can be seen that in Example 4, due to the increase in the content of the chain extender, the tensile strength of the material decreased. This is because the amount of the chain extender and the hydroxyl-containing acrylate are negatively correlated. An increase in the amount of the chain extender will lead to a decrease in the number of C=C introduced into the polymer structure, reducing the intermolecular force and thus lowering the tensile strength of the polyvinyl alcohol-polyurethane sponge. In addition, although an appropriate amount of the chain extender can improve the linearity and crystallinity of the molecular chains and enhance the tensile strength of the material, an excessive amount may lead to too short molecular chains, instead reducing the tensile strength of the material and weakening its ability to withstand external forces. In Example 5, PETA was selected to replace HEA, increasing the content of C=C, which can form a more dense network structure and significantly improve the tensile strength; in addition, the hydrophilic carboxyl group in DMPA forms hydrogen bonds with water, thereby enhancing the adsorption capacity and retaining the excellent water absorption performance of the polyvinyl alcohol sponge.

[0064]

[0065] The present invention prepares a polyvinyl alcohol-polyurethane sponge with a dense three-dimensional crosslinked network structure by means of radiation crosslinking. Through the dual regulation of the radiation dose and C=C, the effective adjustment of the internal crosslinking degree of the polyvinyl alcohol-polyurethane sponge is realized, thereby endowing the polyvinyl alcohol-polyurethane sponge with excellent mechanical properties and ductility. In addition, the preparation process of the present invention does not rely on chemical catalysts, successfully avoiding the problem of using toxic catalysts in traditional preparation methods, significantly improving the application safety of the polyvinyl alcohol-polyurethane sponge in the medical field, and meeting the development requirements of green materials.

[0066] The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be pointed out that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0067] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A preparation method of a flexible polyvinyl alcohol-polyurethane sponge, characterized in that, It includes the following steps: S1: Mix polyethylene glycol and hexamethylene diisocyanate, stir to make them react to obtain an isocyanate-terminated polyurethane prepolymer; S2: Add a hydrophilic chain extender to the isocyanate-terminated polyurethane prepolymer for reaction. The hydrophilic chain extender is dimethylolpropionic acid, and the molar ratio of -OH in dimethylolpropionic acid to -NCO in the isocyanate-terminated polyurethane prepolymer is 0.1~0.9:1; after the reaction is completed, lower the temperature of the reaction system, continue to add a hydroxyl-containing acrylate for reaction, and finally add triethylamine for neutralization reaction to prepare a vinyl-functionalized aqueous polyurethane. Disperse the vinyl-functionalized aqueous polyurethane in water to form a polyurethane aqueous solution; S3: Mix the aqueous solution of polyvinyl alcohol with the polyurethane aqueous solution prepared in S2 and irradiate with electron beam; then perform freeze molding, and finally perform freeze drying to prepare a flexible polyvinyl alcohol-polyurethane sponge.

2. The preparation method of the flexible polyvinyl alcohol-polyurethane sponge according to claim 1, characterized in that, In S1, the molar ratio of polyethylene glycol to hexamethylene diisocyanate is 1:2~3; the stirring temperature is 80~95 °C; the stirring time is 1~3 h.

3. The preparation method of the flexible polyvinyl alcohol-polyurethane sponge according to claim 1, characterized in that, In S1, the molecular weight of polyethylene glycol is 500~5000.

4. The preparation method of the flexible polyvinyl alcohol-polyurethane sponge according to claim 1, wherein In S2, the temperature for adding dimethylolpropionic acid for reaction is 80~90 °C, the reaction time is 0.5~2 h, and after the reaction is completed, the temperature of the reaction system is lowered to 40~60 °C.

5. The preparation method of the flexible polyvinyl alcohol-polyurethane sponge according to claim 1, characterized in that, In S2, the molar ratio of -OH in the hydroxyl-containing acrylate to -NCO in the isocyanate-terminated polyurethane prepolymer is 0.1~0.9:1; the reaction time for adding the hydroxyl-containing acrylate is 3 h; the hydroxyl-containing acrylate is selected from any one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate or pentaerythritol triacrylate; the solid content of the polyurethane aqueous solution is 5~10%.

6. The preparation method of the flexible polyvinyl alcohol-polyurethane sponge according to claim 1, wherein In S3, the volume ratio of the aqueous solution of polyvinyl alcohol to the polyurethane aqueous solution is 1~10:

1.

7. The preparation method of the flexible polyvinyl alcohol-polyurethane sponge according to claim 1, characterized in that, In S3, the irradiation dose is 5~50 kGy; the freeze molding temperature is -15~-30 °C; the freeze molding time is 6~24 h; the freeze drying time is 24~48 h.

8. A flexible polyvinyl alcohol-polyurethane sponge, characterized in that, Prepared by the preparation method described in any one of claims 1-7.

9. Use of a flexible polyvinyl alcohol-polyurethane sponge as described in claim 8, characterized in that, Applied to the preparation of biomedical materials and materials in the field of tissue engineering.

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