A high moisture permeability hydrophilic polyurethane artificial skin membrane based on chemical grafting method, and a preparation method and application thereof

Abstract

This invention belongs to the field of biomedical materials, specifically providing a highly permeable hydrophilic polyurethane artificial membrane based on chemical grafting and its preparation method, comprising the following steps: S1 - Substrate pretreatment: Immersing a polyurethane film in an organic solvent, ultrasonically cleaning and soaking for 0.5-2 hours, then removing and drying to constant weight to obtain a pretreated substrate; S2 - Preparation of hydrophilic modified polyurethane: Completely immersing the substrate obtained in step S1 in a hydrophilic modification solution, introducing an inert gas for 10-30 minutes, heating to 35-45°C, and reacting under stirring or shaking in the dark for 6-24 hours to obtain a hydrophilic modified polyurethane membrane; S3 - Post-treatment: The hydrophilic modified polyurethane membrane from step S2 is sequentially acid-washed, water-washed, and then vacuum-dried to obtain the hydrophilic polyurethane artificial membrane. The hydrophilic polyurethane artificial membrane of this invention, prepared by chemical grafting, possesses high permeability and excellent mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials, specifically relating to a highly moisture-permeable hydrophilic polyurethane artificial membrane based on chemical grafting, its preparation method, and its application. Background Technology

[0002] As the largest organ in the human body, the skin plays a vital barrier role. When subjected to severe burns, trauma, or chronic ulcers, this barrier is compromised, leading to rapid fluid loss and a sharply increased risk of infection. Therefore, ideal artificial skin or wound dressings must effectively mimic the three key properties of natural skin: adequate moisture permeability to prevent fluid buildup, reliable barrier properties to block pathogen invasion, and sufficient flexibility and strength to adhere to and protect the wound.

[0003] Currently widely used synthetic dressings, such as transparent film dressings (e.g., Op-Site®), are primarily made of dense polyurethane or silicone films. While these materials provide good physical barriers and insulation, their water vapor transmission rate is typically below 500 g / m². ² / 24h. In contrast, open wounds, due to epidermal loss, have an extremely high rate of moisture evaporation, approximately 3400-5200 g / m². ² / 24h. This huge difference in moisture permeability makes it very easy for exudate to accumulate under the dressing, causing maceration of healthy skin around the wound and creating a breeding ground for microorganisms, which in turn increases the risk of infection and delays healing.

[0004] To improve moisture permeability, existing technologies have explored modifying hydrophobic polymer substrates using physical or chemical methods. Radiation grafting is a representative approach. As shown in patent US 4,554,317, γ-ray irradiation of a polyester-type polyurethane membrane generates active sites, which are then grafted with hydrophilic monomers such as acrylamide, increasing the moisture permeability to 1000-8000 g / m³. ² The method offers a relatively wide range of 24 hours. However, its industrial application faces significant challenges: First, it relies on expensive radiation equipment such as cobalt sources or electron accelerators, resulting in high initial investment and maintenance costs, as well as special safety management requirements, which hinders large-scale production. Second, the process control is complex; improper control of radiation dose and uniformity can easily lead to degradation of the substrate's main chain, impairing mechanical properties or causing uneven grafting. Third, it is difficult to precisely control the regional selectivity of the grafting reaction; the membrane material may experience internal stress due to differences in the degree of modification on both sides, leading to product curling and deformation, affecting its use.

[0005] In conclusion, developing a novel chemical grafting method that does not rely on high-cost radiation equipment, has a more controllable process, and can achieve uniform grafting while taking into account both high moisture permeability and mechanical properties is of great value for promoting the industrialization and clinical application of high-performance wound dressings. Summary of the Invention

[0006] To address the existing technical problems, the present invention aims to provide a highly moisture-permeable hydrophilic polyurethane artificial membrane based on a chemical grafting method, its preparation method, and its applications. The hydrophilic polyurethane artificial membrane of the present invention is prepared by a chemical grafting method and possesses high moisture permeability and excellent mechanical properties.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a method for preparing a highly moisture-permeable hydrophilic polyurethane artificial membrane based on chemical grafting, comprising the following steps: S1-Substrate Pretreatment: Immerse the polyurethane film in an organic solvent, perform ultrasonic cleaning and soak for 0.5-2 hours, remove and dry to constant weight to obtain the pretreated substrate; S2 - Preparation of hydrophilic modified polyurethane: The substrate obtained in step S1 is completely immersed in the hydrophilic modification liquid, an inert gas is introduced for 10-30 minutes, the temperature is raised to 35-45℃, and the reaction is carried out in the dark for 6-24 hours under stirring or shaking to obtain a hydrophilic modified polyurethane film. S3 - Post-processing: The hydrophilic modified polyurethane membrane from step S2 is sequentially acid-washed, water-washed, and then vacuum-dried to obtain the hydrophilic polyurethane artificial skin membrane.

[0008] This invention pretreats the substrate to thoroughly remove processing aids and antioxidants from the surface and interior of the substrate, resulting in a clean and activated substrate. The pretreated substrate is then immersed in a hydrophilic modification solution for chemical grafting modification. Finally, residual initiators, homopolymers, and unreacted monomers are thoroughly removed by acid washing and water washing, and the substrate is dried to obtain a hydrophilic polyurethane artificial film. This artificial film has excellent moisture permeability, self-adhesion, and mechanical properties.

[0009] In some embodiments of the present invention, in step S1, the organic solvent is acetone or tetrahydrofuran.

[0010] In some embodiments of the present invention, in step S1, the polyurethane film is at least one of polyester-type thermoplastic polyurethane film, ester-ether-type thermoplastic polyurethane film, polyester-type polyurethane film, and polyether-type polyurethane film.

[0011] In some embodiments of the present invention, in step S1, the thickness of the polyurethane film is 20-100 μm.

[0012] Preferably, the thickness of the polyurethane film is 30-50 μm.

[0013] In some embodiments of the present invention, in step S1, the dry tensile modulus of the polyurethane film is ≤1500PSI and the elongation at break is ≥500%.

[0014] In some embodiments of the present invention, in step S2, the hydrophilic modified liquid comprises, by mass percentage, 10-30% of the following raw materials: 10-30% hydrophilic monomer, 0.05-0.3% initiator, pH adjuster and the balance being water.

[0015] In some embodiments of the present invention, the preparation steps of the hydrophilic modified liquid in step S2 are as follows: The hydrophilic monomer is added to water, followed by an initiator, and the pH is adjusted to 2.5-3.5 to obtain the final product.

[0016] In some embodiments of the present invention, in step S2, the hydrophilic monomer is at least one of acrylamide, N-vinylpyrrolidone, and hydroxyethyl methacrylate.

[0017] In some embodiments of the present invention, in step S3, the post-processing involves washing the hydrophilic modified polyurethane film from step S2 sequentially with dilute nitric acid at 45-55°C for 0.8-1.5 hours, then with deionized water at 50-70°C for 30-40 hours, and finally vacuum drying under flat clamping constraints to obtain the final product.

[0018] In some embodiments of the present invention, in step S2, a crosslinking agent accounting for 0.05-0.5% of the total weight of the hydrophilic monomer is also added to the hydrophilic modified liquid.

[0019] In some embodiments of the present invention, the crosslinking agent is at least one of N,N'-methylenebisacrylamide and a biodegradable crosslinking agent.

[0020] In some embodiments of the present invention, the preparation steps of the biodegradable crosslinking agent are as follows: (1) Mix 3,4-dihydroxybenzoic acid and anhydrous ethanol, add potassium carbonate, slowly add epichlorohydrin under an inert atmosphere, stir at 50-60℃ for 4-5 hours, filter and rotary evaporate after the reaction to obtain an epoxy intermediate. (2) Under an inert atmosphere, the epoxy intermediate from step (1) is added to anhydrous THF, followed by 2-mercaptoethanol and triethylamine. The mixture is stirred at 25-28°C for 5-7 hours. After the reaction is completed, the mixture is washed, extracted, dried, rotary evaporated, and subjected to column chromatography to obtain the degradable crosslinking agent.

[0021] In some embodiments of the present invention, in step (1), the mass ratio of 3,4-dihydroxybenzoic acid to epichlorohydrin is 1:(0.8-1.2).

[0022] In some embodiments of the present invention, in step (2), the mass ratio of the epoxy intermediate to 2-mercaptoethanol is 1:(0.4-0.6).

[0023] The biodegradable crosslinking agent prepared in this invention plays a crucial role in constructing a complete mechanical barrier network in the early stages of artificial membrane construction. Simultaneously, by introducing ester bonds, it imparts biodegradable properties to the material, effectively preventing foreign body reactions that may occur if non-degradable materials remain in the body for extended periods. Furthermore, this biodegradable crosslinking agent can fix hydrophilic chains within the polyurethane system to form a stable hydrophilic layer. The 3,4-dihydroxyphenyl structure in its molecular chain further promotes a synergistic balance between hydrophilic permeability and wet adhesion, exhibiting superior overall functionality compared to conventional crosslinking agents.

[0024] Furthermore, the applicant discovered that the presence of multiple crosslinking points in the biodegradable crosslinking agent can form dense crosslinking points on the polyurethane surface, effectively limiting the excessive free movement of hydrophilic segments in an aqueous environment, thereby inhibiting excessive swelling of the grafted layer and improving swelling stability. At the same time, it also offsets the loss of mechanical properties caused by the grafting of hydrophilic chains into the polyurethane to a certain extent, so that the artificial membrane prepared in the end can maintain good interfacial toughness while having high moisture permeability.

[0025] A second aspect of the present invention also provides a highly moisture-permeable hydrophilic polyurethane artificial skin membrane based on chemical grafting obtained by the above preparation method.

[0026] A third aspect of the present invention also provides an application of the highly permeable hydrophilic polyurethane artificial membrane based on chemical grafting obtained by the above technical solution in the field of medical dressings, wherein the hydrophilic polyurethane artificial membrane is transparent, mesh-like, or has a polyurethane outer frame around its edges.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The hydrophilic polyurethane artificial membrane of the present invention is prepared by chemical grafting and has high moisture permeability, self-adhesion and excellent mechanical properties.

[0028] 2. This invention pre-treats the substrate to thoroughly remove processing aids and antioxidants from the surface and interior of the substrate, resulting in a clean and activated substrate. The pre-treated substrate is then immersed in a hydrophilic modification solution for chemical grafting modification. Finally, residual initiators, homopolymers, and unreacted monomers are thoroughly removed by acid washing and water washing, and the substrate is dried to obtain a hydrophilic polyurethane artificial film. This artificial film has excellent moisture permeability, self-adhesion, and mechanical properties.

[0029] 3. This invention prepares a biodegradable crosslinking agent, which imparts biodegradability by introducing ester bonds and avoids foreign body reactions; its 3,4-dihydroxyphenyl structure promotes a synergistic balance between hydrophilic permeability and wet adhesion, making it more functional than conventional crosslinking agents; at the same time, the presence of multiple crosslinking points may improve swelling stability and offset the mechanical loss caused by grafted hydrophilic chains, so that the artificial membrane still maintains excellent interfacial toughness under high permeability. Detailed Implementation

[0030] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0031] To facilitate implementation of this invention by those skilled in the art, the sources of some raw materials in the specific embodiments are described below: The polyurethane film used is Platieron U4101 polyester thermoplastic polyurethane film with a thickness of 25μm, a dry tensile modulus ≤1500 PSI, and an elongation at break ≥500%; other raw materials are available from the market unless otherwise specified.

[0032] Unless otherwise specified, the post-processing steps such as "rotary evaporation", "extraction", "washing" and "column chromatography purification" in the following specific embodiments are routine operations for those skilled in the art, and should be selected according to actual operation.

[0033] Preparation Example 1 The preparation steps of the biodegradable crosslinking agent are as follows: (1) Mix 5g of 3,4-dihydroxybenzoic acid and 50mL of anhydrous ethanol, add 2g of potassium carbonate, slowly add 5g of epichlorohydrin under a nitrogen atmosphere, stir at 55℃ for 4.5h, filter after the reaction, take the filtrate and rotary evaporate to obtain the epoxy intermediate; (2) Under a nitrogen atmosphere, 2g of the epoxy intermediate from step (1) was added to 30mL of anhydrous THF, followed by 1g of 2-mercaptoethanol and 0.2g of triethylamine. The mixture was stirred at 26℃ for 6h. After the reaction was completed, the mixture was washed with dilute hydrochloric acid, extracted with ethyl acetate, dried, purified by rotary evaporation and column chromatography (eluting agent was petroleum ether: ethyl acetate = 3:1 → 1:1 gradient elution) to obtain the degradable crosslinking agent.

[0034] Preparation Example 2 The specific preparation steps of the biodegradable crosslinking agent are the same as those in Preparation Example 1, except that the amount of epichlorohydrin added in step (1) is 6.5g.

[0035] Preparation Example 3 The specific preparation steps of the biodegradable crosslinking agent are the same as those in Preparation Example 1, except that the amount of 2-mercaptoethanol added in step (2) is 1.5g.

[0036] Preparation Example 4 The hydrophilic modification solution contains the following raw materials in 100% by mass: 20% hydrophilic monomers (a mixture of equal masses of acrylamide, N-vinylpyrrolidone and hydroxyethyl methacrylate), 0.3% biodegradable crosslinking agent (added at 0.3% of the total weight of hydrophilic monomers), 0.15% cerium ammonium nitrate, pH adjuster (0.1 mol / L dilute nitric acid), and the balance water.

[0037] The preparation steps of the hydrophilic modified liquid are as follows: add the hydrophilic monomer (acrylamide) and the biodegradable crosslinking agent to water, then add cerium ammonium nitrate, and adjust the pH to 3 with a pH adjuster (0.1 mol / L dilute nitric acid) to obtain the solution.

[0038] The biodegradable crosslinking agent used was obtained from Preparation Example 1.

[0039] Preparation Example 5 The specific preparation steps of the hydrophilic modified liquid are the same as those in Preparation Example 4, except that the degradable crosslinking agent used is obtained from Preparation Example 2.

[0040] Preparation Example 6 The specific preparation steps of the hydrophilic modified liquid are the same as those in Preparation Example 4, except that the degradable crosslinking agent used is obtained from Preparation Example 3.

[0041] Preparation Example 7 The specific preparation steps of the hydrophilic modified liquid are the same as those in Preparation Example 4, except that the biodegradable crosslinking agent used is PEG400DA.

[0042] Preparation Example 8 The specific preparation steps of the hydrophilic modified liquid are the same as those in Preparation Example 4, except that the amount of degradable crosslinking agent added is 0.55% of the total weight of the hydrophilic monomers, based on a mass percentage of 100%.

[0043] Preparation Example 9 The hydrophilic modification solution contains the following raw materials in 100% by mass: 20% hydrophilic monomer (acrylamide), 0.15% cerium ammonium nitrate, N,N'-methylenebisacrylamide (added at 0.3% of the total weight of hydrophilic monomer), pH adjuster (0.1 mol / L dilute nitric acid), and the balance water.

[0044] The preparation steps of the hydrophilic modified liquid are as follows: add hydrophilic monomer (acrylamide) and N,N'-methylenebisacrylamide to water, then add cerium ammonium nitrate, and adjust the pH to 3 with pH adjuster (0.1mol / L dilute nitric acid) to obtain the solution.

[0045] Preparation Example 10 The hydrophilic modification solution contains the following raw materials in 100% by mass: 20% hydrophilic monomer (acrylamide), 0.15% cerium ammonium nitrate, pH adjuster (0.1 mol / L dilute nitric acid) and the balance water.

[0046] The preparation steps of the hydrophilic modified liquid are as follows: add the hydrophilic monomer (acrylamide) to water, then add cerium ammonium nitrate, and adjust the pH to 3 with pH adjuster (0.1mol / L dilute nitric acid) to obtain the solution.

[0047] Example 1 A method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting includes the following steps: S1-Substrate pretreatment: Immerse the polyurethane film in acetone, perform ultrasonic cleaning and soak for 1 hour, remove and dry at 50°C to constant weight to obtain the pretreated substrate. Preparation of S2-hydrophilic modified polyurethane: The substrate obtained in step S1 is completely immersed in the hydrophilic modification liquid, nitrogen is introduced for 20 min, the temperature is raised to 40℃, and the reaction is carried out in the dark for 15 h under stirring to obtain a hydrophilic modified polyurethane film. S3 - Post-processing: The hydrophilic modified polyurethane membrane from step S2 is sequentially acid-washed (0.1 mol / L dilute nitric acid, washed at 50°C for 1 h), water-washed (washed with deionized water at 60°C for 36 h), and then vacuum-dried to obtain the hydrophilic polyurethane artificial skin membrane.

[0048] The hydrophilic modified liquid used in this embodiment was obtained from Preparation Example 4.

[0049] Example 2 A method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting includes the following steps: S1 - Substrate Pretreatment: The polyurethane film is immersed in acetone, ultrasonically cleaned and soaked for 0.5 hours. After removal, it is dried at 50°C to constant weight to obtain the pretreated substrate. Preparation of S2-hydrophilic modified polyurethane: The substrate obtained in step S1 is completely immersed in the hydrophilic modification liquid, nitrogen is introduced for 10 min, the temperature is raised to 45℃, and the reaction is carried out in the dark for 6 h under stirring to obtain a hydrophilic modified polyurethane film. S3 - Post-processing: The hydrophilic modified polyurethane membrane from step S2 is sequentially acid-washed (0.1 mol / L dilute nitric acid, washed at 50°C for 1 h), water-washed (washed with deionized water at 60°C for 36 h), and then vacuum-dried to obtain the hydrophilic polyurethane artificial skin membrane.

[0050] The hydrophilic modified liquid used in this embodiment was obtained from Preparation Example 4.

[0051] Example 3 A method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting includes the following steps: S1-Substrate Pretreatment: The polyurethane film is immersed in acetone, ultrasonically cleaned and soaked for 2 hours, then removed and dried at 50°C to constant weight to obtain the pretreated substrate. Preparation of S2-hydrophilic modified polyurethane: The substrate obtained in step S1 is completely immersed in the hydrophilic modification liquid, nitrogen is introduced for 30 min, the temperature is raised to 35℃, and the reaction is carried out in the dark for 24 h under stirring to obtain a hydrophilic modified polyurethane film. S3 - Post-processing: The hydrophilic modified polyurethane membrane from step S2 is sequentially acid-washed (0.1 mol / L dilute nitric acid, washed at 50°C for 1 h), water-washed (washed with deionized water at 60°C for 36 h), and then vacuum-dried to obtain the hydrophilic polyurethane artificial skin membrane.

[0052] The hydrophilic modified liquid used in this embodiment was obtained from Preparation Example 4.

[0053] Example 4 A method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting is described. The specific implementation method is the same as in Example 1, except that the hydrophilic modification liquid used is obtained from Preparation Example 5.

[0054] Example 5 A method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting is described. The specific implementation method is the same as in Example 1, except that the hydrophilic modification liquid used is obtained from Preparation Example 6.

[0055] Example 6 A method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting is described. The specific implementation method is the same as in Example 1, except that the hydrophilic modification liquid used is obtained from Preparation Example 7.

[0056] Example 7 A method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting is described. The specific implementation method is the same as in Example 1, except that the hydrophilic modification liquid used is obtained from Preparation Example 8.

[0057] Example 8 A method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting is described. The specific implementation method is the same as in Example 1, except that the hydrophilic modification liquid used is obtained from Preparation Example 9.

[0058] Example 9 A method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting is described. The specific implementation method is the same as in Example 1, except that the hydrophilic modification liquid used is obtained from Preparation Example 10.

[0059] Performance testing The hydrophilic polyurethane artificial films prepared in Examples 1-9 above were subjected to the following performance tests, and the specific results are shown in Table 1.

[0060] (1) Water vapor transmission rate: 37℃, 90% RH, determined according to standard YY / T 0471.2-2004; (2) Wet modulus: The elastic modulus under water-absorbing and wet conditions, determined according to standard GB / T 1040.3-2006; (3) Elongation at break: determined according to standard GB / T 1040.3-2006.

[0061] Table 1 As shown in Table 1, the hydrophilic polyurethane artificial membranes prepared in Examples 1-3 have excellent moisture permeability. Comparing Examples 4 and 5 with Example 1, it can be seen that when the amount of epichlorohydrin or 2-mercaptoethanol added in the preparation of the biodegradable crosslinking agent is changed, the former may lead to an overly dense crosslinking network, resulting in a decrease in elongation at break and a significant impact on moisture permeability, while the latter is affected by the disordered distribution of crosslinking points, resulting in a decrease in both moisture permeability and mechanical properties. Comparing Examples 6 and 1, it can be seen that when PEG400DA is used as the biodegradable crosslinking agent, the stability of the hydrophilic layer is poor, the moisture permeability is significantly reduced, and the interfacial toughness is also insufficient. Comparing Examples 7 and 1, it can be seen that when the amount of biodegradable crosslinking agent added is changed, the rigidity of the crosslinking network is enhanced, which in turn leads to varying degrees of inhibition of the moisture permeability and elongation at break of the hydrophilic polyurethane artificial film. Comparing Examples 8 and 9 with Example 1, it can be seen that when N,N'-methylenebisacrylamide is used as the crosslinking agent or no crosslinking agent is added, the overall performance of the hydrophilic polyurethane artificial film is insufficient.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present application in any way. Although the present application discloses the preferred embodiment as described above, it is not intended to limit the present application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. A method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting, characterized in that, Includes the following steps: S1-Substrate Pretreatment: Immerse the polyurethane film in an organic solvent, perform ultrasonic cleaning and soak for 0.5-2 hours, remove and dry to constant weight to obtain the pretreated substrate; S2 - Preparation of hydrophilic modified polyurethane: The substrate obtained in step S1 is completely immersed in the hydrophilic modification liquid, an inert gas is introduced for 10-30 minutes, the temperature is raised to 35-45℃, and the reaction is carried out in the dark for 6-24 hours under stirring or shaking to obtain a hydrophilic modified polyurethane film. S3 - Post-processing: The hydrophilic modified polyurethane membrane from step S2 is sequentially acid-washed, water-washed, and then vacuum-dried to obtain the hydrophilic polyurethane artificial skin membrane.

2. The method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting according to claim 1, characterized in that, In step S1, the polyurethane film is at least one of polyester-type thermoplastic polyurethane film, ester-ether-type thermoplastic polyurethane film, polyester-type polyurethane film, and polyether-type polyurethane film.

3. The method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting according to claim 1, characterized in that, In step S1, the thickness of the polyurethane film is 20-100 μm.

4. The method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting according to claim 1, characterized in that, In step S2, the hydrophilic modified liquid comprises the following raw materials in 100% by mass: 10-30% hydrophilic monomer, 0.05-0.3% initiator, pH adjuster and the balance water.

5. The method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting according to claim 4, characterized in that, In step S2, the hydrophilic monomer is at least one of acrylamide, N-vinylpyrrolidone, and hydroxyethyl methacrylate.

6. The method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting according to claim 4, characterized in that, In step S2, a crosslinking agent accounting for 0.05-0.5% of the total weight of the hydrophilic monomer is also added to the hydrophilic modified liquid.

7. The method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting according to claim 6, characterized in that, The crosslinking agent is at least one of N,N'-methylenebisacrylamide and a biodegradable crosslinking agent.

8. The method for preparing a highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting according to claim 7, characterized in that, The preparation steps of the biodegradable crosslinking agent are as follows: (1) Mix 3,4-dihydroxybenzoic acid and anhydrous ethanol, add potassium carbonate, slowly add epichlorohydrin under an inert atmosphere, stir at 50-60℃ for 4-5 hours, filter and rotary evaporate after the reaction to obtain an epoxy intermediate. (2) Under an inert atmosphere, the epoxy intermediate from step (1) is added to anhydrous THF, followed by 2-mercaptoethanol and triethylamine. The mixture is stirred at 25-28°C for 5-7 hours. After the reaction is completed, the mixture is washed, extracted, dried, rotary evaporated, and subjected to column chromatography to obtain the degradable crosslinking agent.

9. A highly moisture-permeable hydrophilic polyurethane artificial skin based on chemical grafting, obtained by the preparation method according to any one of claims 1-8.

10. The application of the preparation method according to any one of claims 1-8 or the highly moisture-permeable hydrophilic polyurethane artificial skin membrane based on chemical grafting obtained according to claim 9 in the field of medical dressings, characterized in that, The hydrophilic polyurethane artificial membrane is transparent, mesh-like, or has a polyurethane outer frame around its edges.

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