Polymer material for nerve scaffold and preparation method thereof

Abstract

The invention relates to the technical field of polymer materials, and particularly provides a polymer material for a nerve scaffold and a preparation method of the polymer material. The molecular structure of the polymer material contains at least one first block and at least one second block, the first blocks and the second blocks are alternately arranged, and the adjacent first blocks and second blocks are connected through carbamate bonds; the first block is formed from a biodegradable block copolymer diol; the number average molecular weight of the biodegradable block copolymer diol is 2000 to 10000; the second block is formed by polyethylene glycol; and the number-average molecular weight of the polyethylene glycol is 300-2000. Preferably, the molecular weight distribution of the biodegradable block copolymer diol is not higher than 1.5. The polymer material disclosed by the invention has the characteristic of high mechanical strength, and the repairing performance of the nerve scaffold can be improved.

Description

Technical Field

[0001] This application relates to the field of polyurethane technology, and more specifically, to a polymer material for a neural scaffold and a method for preparing the same. Background Technology

[0002] Neural scaffolds are medical materials used for the repair of peripheral nerve injuries. Polyurethane is one of the commonly used polymer materials for peripheral nerve injury repair, possessing good mechanical strength and synthetic flexibility. Biodegradable polyurethane materials can be prepared from biodegradable materials. Nerve guiding catheters for peripheral nerve injury repair made of polyurethane materials are also called polyurethane neural scaffolds. Summary of the Invention

[0003] However, for polyurethane neural scaffolds, the focus is more on their biocompatibility, biodegradability, and role in nerve repair, with less attention paid to their mechanical strength and its impact on other properties. Polyurethane neural scaffolds are typically porous, and this porous structure reduces their mechanical strength, thus affecting their performance, such as nerve repair capabilities. Therefore, it is necessary to improve the mechanical strength of the polyurethane material itself.

[0004] To address the technical problem of insufficient mechanical strength of polyurethane materials used in existing polyurethane neural scaffolds, this application provides a polymer material for neural scaffolds and a method for preparing the same.

[0005] The technical solution adopted in this application is as follows: A polymer material for a neural scaffold, the polymer material having a molecular structure containing at least one first block and at least one second block, the first block and the second block being arranged alternately, and adjacent first blocks and second blocks being connected by urethane bonds; The first block is formed from a biodegradable block copolymer diol; the number average molecular weight of the biodegradable block copolymer diol is 1000-10000; The second block is formed of polyethylene glycol; the number average molecular weight of the polyethylene glycol is 200-2000.

[0006] Preferably, the molecular weight distribution of the biodegradable block copolymer diol is not higher than 1.5.

[0007] Preferably, the biodegradable block copolymer diol comprises soft segments with a glass transition temperature below 0°C and hard segments with a glass transition temperature above 0°C.

[0008] More preferably, the average degree of polymerization of the hard segment block accounts for 1-40% of the average degree of polymerization of the biodegradable block copolymer.

[0009] More preferably, the glass transition temperature of the soft segment block is below -20°C.

[0010] More preferably, the glass transition temperature of the hard segment block is not lower than 20°C.

[0011] Preferably, the number-average molecular weight of the biodegradable block copolymer diol is 3-10 times that of the polyethylene glycol.

[0012] Preferably, the polyurethane material uses a monohydric alcohol as a capping agent, and the general formula of the monohydric alcohol is C0. n H 2n+1 OH, n = 1-6.

[0013] A method for preparing a polymer material for a neural scaffold according to any of the above embodiments, comprising: The biodegradable block copolymer diol and diisocyanate monomer are reacted in a first reaction at a molar ratio of 0.5-0.9:1 to obtain a polyurethane prepolymer; The polyurethane prepolymer and the polyethylene glycol undergo a second reaction at a molar ratio of -NCO and -OH groups of 0.98-1.2:1 to obtain the final product.

[0014] Preferably, after the second reaction, a monohydric alcohol is added for end-capping, wherein the monohydric alcohol has the general formula C0. n H 2n+1 OH, n = 1-6.

[0015] In summary, this application has the following beneficial effects: 1. This application uses a biodegradable block copolymer diol containing hard segments with high glass transition temperature (Tg) and soft segments with low Tg as one of the raw materials. By selecting the molecular weight distribution of the biodegradable block copolymer diol and the ratio of the number average molecular weight of the biodegradable block copolymer diol to polyethylene glycol, a polyurethane material with high mechanical strength is obtained.

[0016] 2. Furthermore, the selection of the hard segment ratio in the biodegradable block copolymer diol can further improve the mechanical strength of polyurethane materials.

[0017] 3. The inventors made an unexpected discovery that improving the mechanical strength of the polyurethane material in the polyurethane neural scaffold itself can enhance the scaffold's ability to repair damaged nerves. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below.

[0019] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.

[0020] This application provides a polymer material for a neural scaffold, wherein the molecular structure of the polymer material contains at least one first block and at least one second block, the first block and the second block are arranged alternately, and adjacent first blocks and second blocks are connected by urethane bonds. The first block is formed from a biodegradable block copolymer diol; the number average molecular weight of the biodegradable block copolymer diol is 1000-10000; The second block is formed of polyethylene glycol; the number average molecular weight of polyethylene glycol is 200-2000.

[0021] Polyurethane materials used in neural scaffolds typically employ biodegradable and biocompatible polymers as raw materials, such as polylactic acid (PLA) and polycaprolactone (PCL). However, existing technologies have limited research on the mechanical strength of polyurethane materials and their impact on the repair function of neural scaffolds. The inventors unexpectedly discovered that the mechanical strength of polyurethane materials affects the repair capacity of neural scaffolds; within a certain range, higher mechanical strength leads to better repair capacity. Biodegradable block copolymer diols and polyethylene glycol both possess good biocompatibility and biodegradability; therefore, the polyurethane neural scaffold of this application also exhibits good biocompatibility and biodegradability. For example, the number-average molecular weight of the biodegradable block copolymer diol can be 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, etc. Further, the number-average molecular weight of the biodegradable block copolymer diol can be 2000-10000. The number average molecular weight of polyethylene glycol can be any value among 200, 300, 400, 600, 800, 1000, 1200, 1500, 1600, 2000, etc. Furthermore, the number average molecular weight of polyethylene glycol can be between 400 and 2000.

[0022] The mechanical strength of polyurethane is related not only to the selected isocyanate monomers and glycol raw materials, but also closely to the physical crosslinking density in the polymer chain, especially at room temperature, where the physical crosslinking density has a significant impact on the mechanical strength of polyurethane. This physical crosslinking density is related to the distribution density and uniformity of urethane bonds, as well as the choice of raw materials. The inventors discovered that the choice of raw materials, their molecular weight, and molecular weight distribution all affect the physical crosslinking density of polyurethane, and thus its mechanical strength.

[0023] In a preferred embodiment of this application, the molecular weight distribution of the biodegradable block copolymer diol is no higher than 1.5. The inventors have discovered that the molecular weight distribution of the biodegradable block copolymer diol affects the mechanical properties of polyurethane materials. Molecular weight distribution is the ratio of the weight-average molecular weight to the number-average molecular weight of polymer molecules. A larger molecular weight distribution indicates a wider molecular weight distribution of the biodegradable block copolymer diol, increasing the proportion of both large and small molecular weights. This, in turn, affects the density and distribution of the physical crosslinking structure in the polyurethane material, which is detrimental to improving mechanical properties. To control the molecular weight distribution of the biodegradable block copolymer diol within a lower range, living polymerization methods, such as living anionic polymerization, can be used. This involves adding one monomer to synthesize one block, then adding another monomer to synthesize another block, a method well-known to those skilled in the art. The molecular weight distribution can be tested using gel permeation chromatography (GPC). For example, the molecular weight distribution of biodegradable block copolymer diols can be any value among 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, etc.

[0024] In a preferred embodiment of this application, the biodegradable block copolymer diol comprises soft segments with a Tg below 0°C and hard segments with a Tg above 0°C. Typically, soft segments with a Tg below 0°C exhibit higher flexibility and lower tensile strength at room temperature; for example, polycaprolactone (PCL) has a Tg of approximately -60°C and a tensile strength generally between 15-25 MPa. Hard segments with a Tg above 0°C exhibit lower flexibility and higher tensile strength at room temperature; for example, polylactic acid (PLA) has a Tg of 60-65°C and a tensile strength above 40 MPa, polyglycolic acid (PGA) has a Tg of 35-40°C and a tensile strength reaching 110 MPa or higher, and lactic acid-glycolic acid copolymer (PLGA) has a Tg of 40-60°C and a tensile strength reaching 60 MPa or higher.

[0025] Ester bonds present in soft and hard segment blocks can also form hydrogen bonds with urethane bonds, as can ether bonds in polyethylene glycol molecules. Therefore, the physical cross-linking structure generated by hydrogen bonds in the polyurethane material structure of this application is relatively complex, containing hydrogen bonds between urethane bonds, hydrogen bonds between ester bonds in soft and hard segment blocks of the biodegradable block copolymer glycol, and hydrogen bonds between urethane bonds and ether bonds in polyethylene glycol.

[0026] In a more preferred embodiment of this application, the average degree of polymerization of the hard segment blocks accounts for 1-40% of the average degree of polymerization of the biodegradable block copolymer. The degree of polymerization refers to the number of repeating units in a polymer or polymer chain segment. In this application, the average degree of polymerization can be calculated by dividing the number-average molecular weight of the chain segment by the molecular weight of the repeating unit. When the average degree of polymerization of the hard segment blocks is within the above range, the polyurethane material can form a more effective physical cross-linking structure, thereby improving mechanical strength. For example, assuming the biodegradable block copolymer is PCL-b-PLA, and the average degree of polymerization of PCL is 60, then the average degree of polymerization of PLA can be 8, 10, 12, 15, 17, 20, 22, 25, 27, 28, 30, 32, 34, 36, 38, 40, etc. Furthermore, the average degree of polymerization of the hard segment blocks accounts for 5-40% of the average degree of polymerization of the biodegradable block copolymer. For example, the percentage can be any value from 5%, 8%, 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, 33%, 35%, 37%, 40%, etc. Even further, the percentage can be 10-40%.

[0027] In a more preferred embodiment of this application, the Tg of the soft segment is below -20°C. A Tg within this range provides better flexibility at room temperature, preventing the polyurethane material from becoming too brittle, which could lead to a decrease in tensile strength or an excessively low elongation at break, thus hindering the use of the neural scaffold.

[0028] In a more preferred embodiment of this application, the Tg of the hard segment is not lower than 20°C. A Tg within this range indicates higher hardness at room temperature, which can improve the mechanical strength of the polyurethane material.

[0029] In a preferred embodiment of this application, the number-average molecular weight of the biodegradable block copolymer diol is 3-10 times that of polyethylene glycol. For example, the number-average molecular weight of the biodegradable block copolymer diol can be 3, 4, 5, 5, 7, 8, 9, or 10 times that of polyethylene glycol. More preferably, the number-average molecular weight of the biodegradable block copolymer diol is 4-8 times that of polyethylene glycol.

[0030] In a preferred embodiment of this application, the polyurethane material uses a monohydric alcohol as a capping agent, and the general formula of the monohydric alcohol is C0. n H 2n+1OH, n = 1-6. The inventors discovered that using monohydric alcohols as end-capping agents for polyurethane materials can significantly reduce the cytotoxicity of polyurethane materials, making them more conducive to nerve regeneration and repair. This may be because the end groups of the polyurethane material still contain residual isocyanates, or a small amount of polymers that did not participate in the reaction due to encapsulation or other reasons, or polymers with high isocyanate content, resulting in insufficiently low cytotoxicity. For example, monohydric alcohols can be methanol, ethanol, isopropanol, etc. Monohydric alcohols have low molecular weight, high hydroxyl activity, and a diluting effect, allowing them to penetrate between polymer chains and react with residual isocyanates to end-cap the isocyanates. There are no particular restrictions on the amount of monohydric alcohol added. Since monohydric alcohols have low boiling points at normal pressure, they can be removed by methods such as normal pressure distillation or vacuum distillation. Therefore, more can be added as needed to reduce the viscosity of the reaction system, which is more conducive to the end-capping of monohydric alcohols.

[0031] Another aspect of this application provides a method for preparing a polymer material for a neural scaffold as described in any of the above embodiments, comprising: A polyurethane prepolymer is obtained by reacting a biodegradable block copolymer diol and a diisocyanate monomer in a molar ratio of 0.5-0.9:1. The polyurethane prepolymer and polyethylene glycol undergo a second reaction at a molar ratio of -NCO to -OH groups of 0.98-1.2:1 to obtain the polyurethane material.

[0032] In the first reaction described above, to accelerate or promote complete reaction, the temperature can be increased, for example to 70-90℃, or a catalyst can be added, such as dibutyltin dilaurate. The amount of catalyst added can be 0.05-0.3% of the weight of the biodegradable block copolymer diol and the diisocyanate monomer. Furthermore, the molar ratio of the biodegradable block copolymer diol to the diisocyanate monomer can be 0.65-0.9:1, such as 0.65:1, 0.671:1, 0.7:1, 0.72:1, 0.75:1, 0.78:1, 0.8:1, 0.82:1, 0.85:1, 0.87:1, 0.9:1, etc.

[0033] In the first reaction described above, there are no particular restrictions on the diisocyanate monomer, which can be IPDI, HDI, TDI, HMDI, etc. However, considering the mechanical strength of polyurethane, IPDI is preferred.

[0034] In the second reaction described above, the reaction can be carried out at 80-110℃, which helps to reduce the viscosity of the reaction system, accelerate the reaction, and promote the complete reaction.

[0035] When -NCO is in excess relative to -OH in the second reaction, for example, when the molar ratio of -NCO to -OH is 1.05-1.2:1, an appropriate chain extender can be added after the second reaction to extend the chain. The chain extender can be a conventional small molecule diol, such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, etc., or a diol containing an oxamide structure, such as N,N-dihydroxyethyl oxamide. In particular, using a diol containing an oxamide structure as a chain extender can further introduce the oxamide structure into the polyurethane polymer chain, forming more hydrogen bond structures, which can increase the density of physical crosslinking structures in the polyurethane structure, optimize the distribution of physical crosslinking structures, and further improve the tensile strength of the polyurethane material.

[0036] In a preferred embodiment of this application, after the second reaction, a monohydric alcohol is added for a capping reaction. The general formula of the monohydric alcohol is C0. n H 2n+1 OH, n = 1-6. If the reaction temperature of the second reaction exceeds the boiling point of the monohydric alcohol at normal pressure, the temperature can be lowered to below the boiling point of the monohydric alcohol after the second reaction. If a chain extender is added after the second reaction, the monohydric alcohol should be added after the chain extension reaction.

[0037] The technical solution of this application will be described in detail below with reference to the embodiments and comparative examples. Unless otherwise specified, the parts in the following embodiments and comparative examples are all parts by weight.

[0038] The following examples and comparative examples use some of the following raw materials: PCL-b-PLA diol 1: PCL segment average degree of polymerization 55.4, PLA segment average degree of polymerization 18.5, number average molecular weight 7675, PLA average degree of polymerization percentage 25%, molecular weight distribution 1.37. PCL-b-PLA diol 2: PCL segment average degree of polymerization 52.7, PLA segment average degree of polymerization 6.3, number average molecular weight 6488, PLA average degree of polymerization percentage 11%, molecular weight distribution 1.24. PCL-b-PLA diol 3: PCL segment average degree of polymerization 63.5, PLA segment average degree of polymerization 34.7, number average molecular weight 9769, PLA average degree of polymerization percentage 35%, molecular weight distribution 1.28. Polyethylene glycol 1: Number average molecular weight 1200; Polyethylene glycol 2: Number average molecular weight 800; Polyethylene glycol 3: Number average molecular weight 1500; Example 1 Under nitrogen protection, PCL-b-PLA diol 1 and IPDI were added to the reaction vessel at a molar ratio of 0.75:1. Then, 0.1% by weight of PCL-b-PLA diol 1 and IPDI and dibutyltin dilaurate were added. The mixture was heated to 70±2℃ and reacted for 2 hours to obtain a polyurethane prepolymer. The above-mentioned polyurethane prepolymer and polyethylene glycol 1 were added to a reaction vessel at a molar ratio of -NCO to -OH groups of 0.98:1. The mixture was heated to 100±℃ and reacted for 3 hours. After cooling to 40℃, a crude product was obtained. The crude product was dissolved in acetone to obtain a 10wt% solution, and then added to methanol in 20 times the volume of acetone for precipitation. The solid was collected and dried overnight in a vacuum oven at 50℃ to obtain the polyurethane material.

[0039] Example 2 The difference between Example 2 and Example 1 is as follows: the temperature was raised to 100±℃ and reacted for 3 hours. After cooling to 40℃, 1% by weight of methanol of the polyurethane prepolymer was added, and the temperature was further raised to micro-reflux of the reaction system. The reaction was carried out for 2 hours to obtain the crude product. The remaining steps remained unchanged.

[0040] Example 3 The difference between Example 3 and Example 1 is that the molar ratio of PCL-b-PLA diol 1 and IPDI is adjusted from 0.75:1 to 0.65:1. The remaining steps remain unchanged.

[0041] Example 4 The difference between Example 4 and Example 1 is that the molar ratio of PCL-b-PLA diol 1 and IPDI is adjusted from 0.75:1 to 0.9:1. The remaining steps remain unchanged.

[0042] Example 5 The difference between Example 5 and Example 1 is that polyethylene glycol 1 is replaced with an equimolar amount of polyethylene glycol 2. The remaining steps remain unchanged.

[0043] Example 6 Under nitrogen protection, PCL-b-PLA diol 2 and IPDI were added to a reaction vessel at a molar ratio of 0.8:1. Then, 0.1% by weight of PCL-b-PLA diol 2 and IPDI and dibutyltin dilaurate were added. The mixture was heated to 70±2℃ and reacted for 2 hours to obtain a polyurethane prepolymer. The above-mentioned polyurethane prepolymer and polyethylene glycol 2 were added to a reaction vessel at a molar ratio of -NCO to -OH groups of 1.07:1. The mixture was heated to 100±℃ and reacted for 3 hours. After cooling, a crude product was obtained. The crude product was dissolved in acetone to obtain a 10wt% solution, and then added to methanol in 20 times the volume of acetone for precipitation. The solid was collected and dried overnight in a vacuum oven at 50℃ to obtain the polyurethane material.

[0044] Example 7 The difference between Example 7 and Example 6 is as follows: the temperature was raised to 100±℃ and reacted for 3 hours. After cooling to 40℃, 2% by weight of methanol of the polyurethane prepolymer was added, and the temperature was further raised to micro-reflux of the reaction system. The reaction was continued for 2 hours to obtain the crude product. The remaining steps remained unchanged.

[0045] Example 8 The difference between Example 8 and Example 6 is that the molar ratio of -NCO and -OH groups in the polyurethane prepolymer and polyethylene glycol 2 is adjusted from 1.07:1 to 1.15:1. The remaining steps remain unchanged.

[0046] Example 9 The difference between Example 9 and Example 7 is that after heating to 100±℃ and reacting for 3 hours, before cooling, 15% (molar amount) of ethylene glycol of the polyurethane prepolymer was added for a chain extension reaction for 2 hours. The remaining steps remained unchanged.

[0047] Example 10 The difference between Example 10 and Example 9 is that ethylene glycol is replaced with an equimolar amount of N,N-dihydroxyethyl oxalamide. The remaining steps remain unchanged.

[0048] Example 11 The difference between Example 11 and Example 6 is that PCL-b-PLA diol 2 is replaced with an equimolar amount of PCL-b-PLA diol 3. The remaining steps remain unchanged.

[0049] Example 12 The difference between Example 12 and Example 6 is that polyethylene glycol 2 is replaced with an equimolar amount of polyethylene glycol 3. The remaining steps remain unchanged.

[0050] Example 13 The difference between Example 13 and Example 6 is that after heating to 100±℃ and reacting for 3 hours, before cooling, 7% (molar amount) of 1,4-butanediol from the polyurethane prepolymer was added for a chain extension reaction for 2 hours. The remaining steps remained unchanged.

[0051] Example 14 The difference between Example 14 and Example 6 is that after heating to 100±℃ and reacting for 3 hours, before cooling, 10% (molar amount) of N,N-dihydroxyethyl oxalamide of the polyurethane prepolymer was added for a chain extension reaction for 2 hours. The remaining steps remained unchanged.

[0052] Example 15 The difference between Example 15 and Example 6 is as follows: After reacting at 100±℃ for 3 hours, before cooling, 10% (by molar weight) of N,N-dihydroxyethyl oxalamide of the polyurethane prepolymer was added for chain extension reaction for 2 hours. After cooling to 60℃, 3% (by weight) of anhydrous ethanol of the polyurethane prepolymer was added, and the temperature was further increased to micro-reflux of the reaction system for 2 hours to obtain the crude product. The remaining steps remained unchanged.

[0053] Comparative Example 1 The difference between Comparative Example 1 and Example 6 is that PCL-b-PLA diol 2 is replaced with an equimolar amount of PCL-b-PLA diol 4. The remaining steps remain unchanged.

[0054] PCL-b-PLA diol 4: PCL segment average degree of polymerization 80.4, PLA segment average degree of polymerization 30.7, number average molecular weight 11416, PLA average degree of polymerization percentage 28%, molecular weight distribution 1.24.

[0055] Comparative Example 2 The difference between Comparative Example 2 and Example 6 is that PCL-b-PLA diol 2 is replaced with an equimolar amount of PCL-b-PLA diol 5. The remaining steps remain unchanged.

[0056] PCL-b-PLA diol 5: PCL segment average degree of polymerization 55.3, PLA segment average degree of polymerization 6.8, number average molecular weight 6821, PLA average degree of polymerization percentage 11%, molecular weight distribution 1.64.

[0057] Comparative Example 3 The difference between Comparative Example 3 and Example 6 is that polyethylene glycol 2 is replaced with an equimolar amount of polyethylene glycol 4. The remaining steps remain unchanged.

[0058] Polyethylene glycol 4: Number average molecular weight 2800.

[0059] Performance testing Tensile strength test: The test shall be conducted in accordance with the method of GB / T528-2009.

[0060] Cytotoxicity: The direct contact method according to ISO 10993-5 was used to test the cell line L929. The survival rate of normal cells was observed and calculated.

[0061] The results are shown in Table 1 below.

[0062] Table 1 As shown in Table 1, the polyurethane of this application can achieve higher tensile strength through structural design. Moreover, after end-capping with methanol or ethanol, the toxicity to cells is significantly reduced and the cell survival rate is significantly improved. Compared with using small molecule diols as chain extenders, the polyurethane material obtained by using N,N-dihydroxyethyl oxalamide as a chain extender has significantly higher tensile strength.

[0063] Application testing Application tests for nerve repair were conducted using the polyurethane materials of Examples 6, 10, 14 and 15, as well as Comparative Examples 1 and 2.

[0064] Comparative Application: Using sodium chloride as a pore-forming agent and employing a water displacement method to form pores: Nano-sized sodium chloride was dispersed into polyurethane material and mixed evenly. After extrusion molding and water displacement processes, a polyurethane neural scaffold was formed with an inner diameter of 4 mm, a wall thickness of 0.5 mm, and a length of 10 cm.

[0065] In the application of polyurethane nerve scaffolds in the repair of peripheral nerve injuries, a rat sciatic nerve transection model was used to evaluate their repair capabilities. The procedure included: anesthetizing rats and removing 8 mm of the left sciatic nerve while anesthetized, taking care not to completely sever the nerve sheath. After resection, the polyurethane nerve scaffold to be tested was placed at the sciatic nerve transection site, and the nerve sheath and wound were sutured. The time to the onset of regeneration and the time to complete repair were observed. The results are shown in Table 2 below.

[0066] Table 2 As shown in Table 2, the repair performance of the neural scaffold is positively correlated with its mechanical strength; higher mechanical strength leads to faster repair. Chain extension with a chain extender improved the tensile strength of the polyurethane material, while also shortening the time to the start of regeneration and the time to full repair. Further end-capping with ethanol reduced cytotoxicity and further shortened the time to the start of regeneration and the time to full repair.

[0067] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A polymer material for a neural scaffold, characterized in that, The polymer material contains at least one first block and at least one second block in its molecular structure, the first block and the second block are arranged alternately, and adjacent first blocks and second blocks are connected by urethane bonds; The first block is formed from a biodegradable block copolymer diol; the number average molecular weight of the biodegradable block copolymer diol is 1000-10000; The second block is formed of polyethylene glycol; the number average molecular weight of the polyethylene glycol is 200-2000.

2. The polymer material for neural scaffolds according to claim 1, characterized in that, The molecular weight distribution of the biodegradable block copolymer diol is not higher than 1.

5.

3. The polymer material for neural scaffolds according to claim 1, characterized in that, The biodegradable block copolymer diol comprises soft segments with a glass transition temperature below 0°C and hard segments with a glass transition temperature above 0°C.

4. The polymer material for neural scaffolds according to claim 3, characterized in that, The average degree of polymerization of the hard segment block accounts for 1-40% of the average degree of polymerization of the biodegradable block copolymer.

5. The polymer material for neural scaffolds according to claim 3, characterized in that, The glass transition temperature of the soft segment block is below -20°C.

6. The polymer material for neural scaffolds according to claim 3, characterized in that, The glass transition temperature of the hard segment block is not lower than 20°C.

7. The polymer material for neural scaffolds according to claim 1, characterized in that, The number-average molecular weight of the biodegradable block copolymer diol is 3-10 times that of the polyethylene glycol.

8. The polymer material for neural scaffolds according to claim 1, characterized in that, The polyurethane material uses a monohydric alcohol as a capping agent, and the general formula of the monohydric alcohol is C0. n H 2n+1 OH, n=1-6.

9. A method for preparing a polymer material for a neural scaffold according to any one of claims 1-7, characterized in that, include: The biodegradable block copolymer diol and diisocyanate monomer are reacted in a first reaction at a molar ratio of 0.5-0.9:1 to obtain a polyurethane prepolymer; The polyurethane prepolymer and the polyethylene glycol undergo a second reaction at a molar ratio of -NCO and -OH groups of 0.98-1.2:1 to obtain the final product.

10. The method for preparing the polymer material for the neural scaffold according to claim 9, characterized in that, Following the second reaction, a monohydric alcohol is added for end-capping, wherein the monohydric alcohol has the general formula C0. n H 2n+1 OH, n=1-6.

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