Four-arm polyethylene glycol amine as well as preparation method and application thereof

Abstract

The invention discloses four-arm polyethylene glycol amine as well as a preparation method and application thereof, relates to the technical field of high polymer materials, and solves the problems of poor comprehensive properties such as strength, fatigue resistance and swelling resistance when traditional dual-network hydrogel is applied to preparation of a cartilage repair material in the prior art. The molecular weight of four-arm polyethylene glycol amine provided by the invention is 10 kDa or 40 kDa, four-arm polyethylene glycol, phthalimide, diisopropyl azodicarboxylate and triphenylphosphine are subjected to a Mitsunobu reaction and hydrazinolysis, and the four-arm polyethylene glycol amine with the molecular weight of 10 kDa is obtained; four-arm polyethylene glycol, phthalimide, diisopropyl azodicarboxylate and triphenylphosphine are subjected to a Mitsunobu reaction and hydrazinolysis, and four-arm polyethylene glycol amine with the molecular weight of 40 kDa is obtained. The double-network hydrogel prepared from the four-arm polyethylene glycol amine has excellent comprehensive performance such as high mechanical strength, fatigue resistance, self-recovery performance and swelling resistance, and can be applied to preparation of cartilage-like materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high molecular materials, in particular to a four-arm polyethylene glycol amine, a preparation method thereof and application thereof in preparation of cartilage-like materials. BACKGROUND

[0002] In recent years, hydrogels have good water absorption, biocompatibility, environmental responsiveness and controllable physical and chemical properties as ideal cartilage replacement materials. However, the existing hydrogels have problems such as insufficient mechanical strength, poor fatigue resistance, easy swelling and structural instability when facing external mechanical stress and long-term use, which are difficult to meet the use requirements of joint cartilage under high-strength load and complex motion environment for a long time. Therefore, how to improve the mechanical strength, durability and structural stability of the material while ensuring its biocompatibility is a technical problem to be solved in the application of hydrogels in the field of cartilage repair materials.

[0003] To solve the above problem, in 2003, researchers proposed the concept of "double network hydrogel", which made breakthrough progress in improving the mechanical properties of hydrogels. This kind of hydrogel is usually composed of two polymer networks with different physical properties and mutual penetration, in which the brittle network breaks as an energy dissipation unit when stressed, and the flexible network maintains the overall structural stability, thereby significantly improving the strength, toughness and environmental adaptability of the material. Compared with traditional single network hydrogels, double network hydrogels can withstand higher tension and compression, have better ductility and durability, and therefore have attracted widespread attention in the field of cartilage repair materials. However, the mechanical strength of the existing double network hydrogels still lags behind that of natural cartilage, and it is easy to cause fatigue damage and structural degradation under long-term high load and repeated stress, which is difficult to maintain stable support. In addition, the existing double network hydrogels as cartilage materials are prone to volume swelling and tissue mismatch in body fluid environment, which affects the repair effect and stability after implantation. Therefore, how to further improve the mechanical strength, fatigue resistance and anti-swelling stability while ensuring good biocompatibility is a core problem to be solved in the application of double network hydrogels in the field of cartilage repair. SUMMARY

[0004] In order to solve the problem that the traditional double network hydrogel has poor comprehensive performance such as strength, fatigue resistance and swelling resistance when applied to the preparation of cartilage repair materials in the prior art, the present application provides a four-arm polyethylene glycol amine, a preparation method thereof and application thereof. The technical scheme of the present application is as follows: A preparation method of a four-arm polyethylene glycol amine, wherein the molecular weight of the four-arm polyethylene glycol amine is 10 kDa or 40 kDa. The preparation steps of the four-arm polyethylene glycol amine with a molecular weight of 10 kDa are as follows: four-arm polyethylene glycol, phthalimide, azodicarboxylic acid diisopropyl ester and triphenylphosphine are subjected to Mitsunobu reaction and hydrazinolysis to obtain the four-arm polyethylene glycol amine with a molecular weight of 10 kDa. The preparation steps of the four-arm polyethylene glycol amine with a molecular weight of 40 kDa are as follows: four-arm polyethylene glycol, triethylamine, methyl sulfonyl chloride, phthalimide and azodicarboxylic acid diisopropyl ester are subjected to Mitsunobu reaction and hydrazinolysis to obtain the four-arm polyethylene glycol amine with a molecular weight of 40 kDa.

[0005] Further, the preparation steps of the four-arm polyethylene glycol amine with a molecular weight of 10 kDa are as follows: four-arm polyethylene glycol, phthalimide and triphenylphosphine are dissolved in anhydrous tetrahydrofuran, a tetrahydrofuran solution containing azodicarboxylic acid diisopropyl ester is added dropwise, stirring is performed for one week, the solvent is removed, the residue is dissolved and filtered, extraction is performed, the organic phase is dried with anhydrous sodium sulfate, filtration and concentration are performed; the product is precipitated from the organic phase with ether three times to obtain a light yellow powder; the light yellow powder is dissolved in tetrahydrofuran and refrigerated, suction filtration is performed at room temperature, the filter cake is dried, normal hexane is added twice to pulp, suction filtration is performed, and natural air drying is performed to obtain the monomer four-arm polyethylene glycol amine with a molecular weight of 10 kDa; the refrigeration time of the light yellow powder dissolved in tetrahydrofuran is 48 h; the molar ratio of the four-arm polyethylene glycol, phthalimide, azodicarboxylic acid diisopropyl ester and triphenylphosphine is 1:5:5:5.

[0006] Further, the preparation steps of the four-arm polyethylene glycol amine with a molecular weight of 40 kDa are as follows: triethylamine and methyl sulfonyl chloride are added to a solution of four-arm polyethylene glycol in anhydrous dichloromethane, reaction is performed in an ice bath environment, after the reaction is completed, temperature is increased and stirring is performed, the reaction product is purified by ether pulp to obtain an intermediate; the intermediate, phthalimide and azodicarboxylic acid diisopropyl ester are dissolved in anhydrous tetrahydrofuran to react, the product is dissolved in ethanol, 80% hydrazine hydrate is added, reflux reaction is performed, the crude product is dissolved and filtered, extraction is performed, the organic phase is dried with anhydrous sodium sulfate, filtration and concentration are performed; the product is precipitated from the organic phase with ether three times to obtain a brown powder; the brown powder is dissolved in tetrahydrofuran and refrigerated, suction filtration is performed at room temperature, the filter cake is dried, normal hexane is added twice to pulp, suction filtration is performed, and natural air drying is performed to obtain the monomer four-arm polyethylene glycol amine with a molecular weight of 40 kDa; the molar ratio of the four-arm polyethylene glycol, triethylamine, methyl sulfonyl chloride, phthalimide and azodicarboxylic acid diisopropyl ester is 1:4.3:1.3:4.2:5.

[0007] Further, the reaction time in the ice bath environment is 8 h; after the reaction is completed, the temperature is increased to 25°C; the stirring time is 48 h.

[0008] Further, the temperature of the reaction of the intermediate, phthalimide and diisopropyl azodicarboxylate in anhydrous tetrahydrofuran is 60 DEG C, and the reaction time is 3 days.

[0009] Further, the reflux reaction time is 8 h, and the time of dissolving the brown powder in tetrahydrofuran and refrigerating is 48 h.

[0010] A four-arm polyethylene glycol amine is prepared by the preparation method.

[0011] The four-arm polyethylene glycol amine is applied to preparation of cartilage-like material.

[0012] Further, the four-arm polyethylene glycol amine is applied to preparation of four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel.

[0013] Further, the preparation steps of the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel are as follows: S1: adding 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide into phosphate buffer solution containing the four-arm polyethylene glycol amine, stirring, adding polyacrylic acid for reaction to obtain a bottom layer hydrogel material; S2: immersing the bottom layer hydrogel material in FeCl3 solution, pouring into a mold after taking out, removing bubbles, and performing continuous freeze-thaw cycle to obtain the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel; The molar ratio of the four-arm polyethylene glycol amine to polyacrylic acid is 1:0.75, and the molar ratio of the four-arm polyethylene glycol amine to 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide is 1:2.2:2.5.

[0014] Compared with the prior art, the application solves the problem of poor comprehensive performance such as strength, fatigue resistance and swelling resistance of the traditional double network hydrogel in the preparation of cartilage repair material in the prior art, and has the following beneficial effects: 1. Excellent fatigue resistance and self-recovery performance: by adjusting the molecular weight of the four-arm polyethylene glycol amine, the double network structure with flexible chain segments and strong interaction is constructed, so that the hydrogel can effectively disperse and dissipate external stress in the cyclic loading process, avoid structural damage caused by stress concentration, and still have significant mechanical stability under the action of multiple cyclic compression and stretching. Under the compression strain of 80%, the stress of the double network hydrogel is as high as 30.8 MPa, and the toughness is as high as 3.82 MJ / m 3; the peak stress remains at 99.8% of the initial stress value after 10 cycles of loading and unloading, and the recovery rates of the elastic modulus and dissipated energy during the short recovery process are close to 100%, fully verifying the fatigue resistance and rapid self-recovery characteristics of the double network hydrogel provided by the application under long-term stress environment, which has potential application value in the field of cartilage substitute materials.

[0015] 2. High strength and significant anti-swelling performance: the present application introduces polyacrylic acid rigid segments into the four-arm polyethylene glycol amine flexible network to form an interpenetrating double network structure, thereby realizing effective energy transmission and dispersion under external force, significantly improving the overall strength and structural stability of the material, and effectively improving the peak stress and more excellent deformation bearing capacity. At the same time, the multiple carboxyl groups in the polyacrylic acid segment form stable hydrogen bond interactions with water molecules, limiting the excessive entry of water molecules, significantly reducing the swelling rate (swelling rate is 1.5), and making the hydrogel maintain a low volume change and long-term stability in different solution environments (deionized water, physiological saline and high-concentration urea solution). The synergistic improvement of strength and anti-swelling performance enables the hydrogel to maintain a stable three-dimensional structure in a simulated body fluid environment, ensuring its applicability and durability as a cartilage substitute material in complex physiological environments.

[0016] 3. Suitable for large-scale application: the double network hydrogel prepared by using four-arm polyethylene glycol amine provided by the application has excellent comprehensive performance such as high mechanical strength, fatigue resistance, self-recovery and anti-swelling performance; the preparation process is mild, the steps are simple, the raw materials are easy to obtain and the cost is low, avoiding the dependence on expensive rare materials or high energy consumption process, the preparation process is green and environmentally friendly, has good economic feasibility, and meets the needs of sustainable development. It can be widely used in the preparation of materials in the fields of joint cartilage repair, artificial soft tissue replacement, medical cushioning materials and flexible biological devices. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is the nuclear magnetic resonance hydrogen spectrum of monomer four-arm polyethylene glycol amine with a molecular weight of 10 kDa; Figure 2 is the infrared spectrum of four-arm polyethylene glycol amine (10 kDa)-polyacrylic acid double network hydrogel; Figure 3 is the nuclear magnetic resonance hydrogen spectrum of monomer four-arm polyethylene glycol amine with a molecular weight of 40 kDa; Figure 4 is the infrared spectrum of four-arm polyethylene glycol amine (40 kDa)-polyacrylic acid double network hydrogel; Figure 5 is the stress-strain curve of the double network hydrogel; Figure 6 is the elastic modulus and dissipated energy test diagram of the double network hydrogel; Figure 7 Toughness map of the double network hydrogel; Figure 8 Stress-strain curve of the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel under loading-unloading cycle; Figure 9 Mechanical property change of the double network hydrogel under different cycle times; Figure 10 Stress-strain curve of the double network hydrogel under different recovery times; Figure 11 Mechanical property recovery of the double network hydrogel; Figure 12 Stress-strain curve of the double network hydrogel in the cyclic tensile test; Figure 13 Mechanical property change of the double network hydrogel in the cyclic tensile test; Figure 14 Swelling property test results of the double network hydrogel. DETAILED DESCRIPTION

[0018] In order to make the technical solutions of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings of the specification of the present application. It should be noted that the following embodiments are only used to better understand the technical solutions of the present application, and should not be understood as a limitation of the present application.

[0019] Example 1. P1: Dry four-arm polyethylene glycol (5 g, 2 mmol), phthalimide (1.47 g, 10 mmol, 5 eq) and triphenylphosphine (2.62 g, 10 mmol, 5 eq) were dissolved in 40 mL of anhydrous tetrahydrofuran, 10 mL of a tetrahydrofuran solution containing azobisdimethylvaleric acid diisopropyl ester (2.03 g, 10 mmol, 5 eq) was added dropwise, the mixture was stirred at room temperature for 7 days, the solvent was removed under vacuum, the residue was dissolved in water and filtered, the aqueous solution was saturated with sodium chloride, extracted with dichloromethane, the organic phase was dried with anhydrous sodium sulfate, filtered and concentrated; the product was precipitated from the organic phase with diethyl ether three times to obtain a light yellow powder; the light yellow powder was dissolved in tetrahydrofuran (1 g / 5 mL) and placed in a refrigerator for 48 h, then filtered under vacuum at room temperature (add an equal volume of n-hexane 1 g / 5 mL), dry the filter cake, add n-hexane (1 g / 10 mL) and beat twice at room temperature, filter under vacuum and air dry to obtain a monomer four-arm polyethylene glycol amine with a molecular weight of 10 kDa. The proton nuclear magnetic resonance spectrum of the 10 kDa monomer four-arm polyethylene glycol amine is shown in Figure 1 The nuclear magnetic resonance characterization results are as follows: 1H NMR (500 MHz, Chloroform) δ 3.86 – 3.45 (m, 908H), 3.35 (s, 8H), 1.86 (m, 8H), 1.92 (s, 8H); P2: Weigh four-armed polyethylene glycolamine (10 kDa), 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and polyacrylic acid (5.76 kDa) in a molar ratio of 1:2.2:2.5:0.75; dissolve the four-armed polyethylene glycolamine (10 kDa) in phosphate buffer, then add 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide, stir at room temperature for 10 min, then add polyacrylic acid to the system and react at pH 7 for 8 h to obtain the bottom hydrogel material; P3: The bottom hydrogel material was immersed in FeCl3 solution for 3 h, then removed and poured into a mold. It was allowed to stand at room temperature to remove air bubbles, then placed in a -25°C freezer for 24 h, followed by 5 h at room temperature. This freeze-thaw cycle was repeated 10 times to obtain a four-armed polyethylene glycolamine-polyacrylic acid dual-network hydrogel. The infrared spectral results of the four-armed polyethylene glycolamine-polyacrylic acid dual-network hydrogel are shown below. Figure 2 As shown, at 3222cm -1 The absorption peak appearing at 1690 cm⁻¹ is the stretching vibration peak of the amino group. -1 The stretching vibration peak of the carbonyl group of the amide bond appears at 1520 cm⁻¹. -1 The bending vibration peak of the amino group appears at 1129 cm⁻¹. Due to the intramolecular hydrogen bonding, the electron cloud shifts back towards the electronegative atom, corresponding to a shift of the infrared absorption peak towards lower wavenumbers, reaching 1129 cm⁻¹. -1 The peak at this point represents the stretching vibration of the ether bond, indicating that the hydrogel contains the above-mentioned groups, thus proving the successful preparation of the hydrogel sample.

[0020] Example 2. P1: Triethylamine (4.3 eq) and methanesulfonyl chloride (1.3 eq) were added to an anhydrous dichloromethane solution containing tetra-armed polyethylene glycol in a three-necked flask. The reaction was carried out in an ice bath for 8 h, then heated to 25 °C and stirred for 48 h. After the reaction was completed, the reactants were purified by slurrying with diethyl ether to obtain an intermediate. The intermediate, phthalimide (4.2 eq), and diisopropyl azodicarboxylate (5 eq) were dissolved in anhydrous tetrahydrofuran and reacted at 60 °C for 3 days. The product was dissolved in ethanol, and 80% hydrazine hydrate (11.5 eq) was added. The mixture was refluxed for 8 h. After the reaction was completed, the crude product was dissolved in water and filtered. The aqueous solution was saturated with sodium chloride and extracted with dichloromethane. The organic phase was dried with anhydrous sodium sulfate, filtered, and concentrated. The product was precipitated from the organic phase three times with diethyl ether to obtain a brown powder. The brown powder was dissolved in tetrahydrofuran (1 g / 10 mL) and refrigerated for 48 h. The mixture was then filtered at room temperature (with an equal volume of n-hexane added). After drying the filter cake, hexane (1 g / 30 mL) was added, and the mixture was stirred twice at room temperature. The mixture was then filtered and air-dried to obtain a monomeric four-armed polyethylene glycolamine with a molecular weight of 40 kDa. The 1H NMR spectrum is shown below. Figure 3 As shown, the NMR characterization results are as follows: 1 H NMR (500 MHz, Chloroform) δ 3.89 – 3.38 (m, 3636H), 3.32 (s, 8H), 3.17 (m, 8H), 1.85 (s, 8H); P2: Weigh four-armed polyethylene glycolamine (40 kDa), 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and polyacrylic acid (5.76 kDa) in a molar ratio of 1:2.2:2.5:0.75; dissolve the four-armed polyethylene glycolamine (40 kDa) in phosphate buffer, then add 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide, stir at room temperature for 10 min, then add polyacrylic acid to the system and react at pH 7 for 8 h to obtain the bottom hydrogel material; P3: The bottom hydrogel material was immersed in FeCl3 solution for 3 h, then removed and poured into a mold. It was allowed to stand at room temperature to remove air bubbles, then placed in a -25°C freezer for 24 h, followed by 5 h at room temperature. This freeze-thaw cycle was repeated 10 times to obtain a four-armed polyethylene glycolamine-polyacrylic acid dual-network hydrogel. The infrared spectral results of the four-armed polyethylene glycolamine-polyacrylic acid dual-network hydrogel are shown below. Figure 4 As shown, it can be found at 3230cm. -1 The absorption peak appearing at 1660 cm⁻¹ is the stretching vibration peak of the amino group. -1 The stretching vibration peak of the carbonyl group exhibiting the amide bond appears at 1500 cm⁻¹. -1The bending vibration peak at the amino group is shifted to the electrically negative atom due to the effect of intramolecular hydrogen bond, and the electron cloud is offset, so the corresponding infrared absorption peak will move to the low wave number direction, and the stretching vibration peak at 1120 cm -1 The stretching vibration peak at 1120 cm

[0021] The four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel prepared in Example 1 and Example 2 was made into a cylindrical shape, and compression experiments were carried out at a compression rate of 10 mm / min, as shown in FIG. 6. Figure 5 The stress-strain curve of the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel is shown in FIG. 6, and it can be seen from the figure that when the four-arm polyethylene glycol amine with a molecular weight of 40 kDa is used as the crosslinking framework, the compression stress of the obtained double network hydrogel reaches 30.8 MPa, which is significantly higher than that of the corresponding hydrogel prepared when the molecular weight is 10 kDa, proving that the four-arm polyethylene glycol amine with a large molecular weight helps to improve the compression resistance of the hydrogel. As shown in FIG. 7, Figure 6 The elastic modulus and dissipation performance of the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel are shown in FIG. 7, and it can be seen from the figure that the elastic modulus of the double network hydrogel prepared by the four-arm polyethylene glycol amine with a molecular weight of 40 kDa is 9.45 MPa, and the dissipation energy is 0.31 MJ / m 3 As shown in FIG. 8, Figure 7 It can be seen that the toughness of the double network hydrogel prepared by the four-arm polyethylene glycol amine with a molecular weight of 40 kDa is 3.82 MJ / m 3 , which is better than that of the corresponding hydrogel prepared when the molecular weight is 10 kDa, proving that the four-arm polyethylene glycol amine with a high molecular weight (40 kDa) can effectively improve the mechanical properties of the double network hydrogel. The obtained material has high strength, high modulus and excellent toughness, showing that the double network hydrogel prepared by the application has broad potential application in the fields of cartilage replacement, flexible support material and impact-resistant slow-release material, and subsequent research selects the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel with a molecular weight of 40 kDa to carry out further performance test.

[0022] Fatigue resistance test: The four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel prepared in Example 2 was subjected to 10 cycles of loading-unloading experiments under the compression conditions of 50% stress and loading rate of 10 mm / min and the tensile conditions of 100% stress and loading rate of 100 mm / min. As shown in FIG. 9, Figure 8 The cyclic loading-unloading stress-strain curve of the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel is shown in FIG. 9, and it can be seen from the figure that the cyclic stress-strain curve of the hydrogel is still highly overlapped after multiple cycles, and there is no obvious shift or attenuation. As shown in FIG. 10, Figure 9Further shows the mechanical property change of the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel under different cycle times, from the figure, the peak stress of the double network hydrogel always remains at about 99.8% of the initial value, and the dissipation energy is stably maintained at about 24.68 kJ / m 3 , indicating that the hydrogel still has excellent fatigue resistance under long-time repeated stress.

[0023] Self-repairing performance test: The four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel prepared in Example 2 was subjected to self-recovery performance test, as Figure 10 The stress-strain curve of the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel under different recovery times is shown, with the extension of recovery time, the mechanical properties of the material gradually recover, and when the recovery time reaches 100 s, the overall recovery rate is as high as 99.99%. Figure 11 The mechanical property recovery of the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel under different recovery times is given, it can be observed that after 100 s recovery, the recovery rates of the elastic modulus and the dissipation energy can reach 100%, fully illustrating that the double network hydrogel has fast and efficient self-recovery ability. In summary, the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel prepared by the present application not only shows excellent fatigue resistance, but also has excellent fast self-recovery ability, which provides strong support for the development of cartilage substitute materials.

[0024] Tensile property test: The four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel prepared in Example 2 was subjected to tensile test at a rate of 100 mm / min, and after reaching the set strain, it was recovered to the initial state at the same rate, and the cycle loading-unloading was continuously carried out for 10 times. As Figure 12 The stress-strain curve of the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel subjected to cyclic tensile test is shown, from the figure, it can be seen that the cyclic tensile stress-strain curve is still highly coincident after 10 cycles, and no obvious performance attenuation is observed. As Figure 13 The mechanical property change of the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel subjected to cyclic tensile test is shown, the results show that after 10 cycles of tensile test, the peak stress of the hydrogel is 0.84 MPa, which remains at 98.85% of the initial value, fully proving that the double network hydrogel has excellent fatigue resistance and structural stability.

[0025] Swelling property test: The four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel prepared in Example 2, which was cut into 20 mm x 20 mm, was respectively placed in deionized water, 0.9% NaCl solution and 5 mol / L urea solution, and swelling experiments were carried out at 37°C. The samples were taken out at regular time intervals within 0-100 h and wiped dry and weighed until the sample reached swelling equilibrium. Figure 14 As shown in the figure, the swelling rate of the hydrogel in the urea solution is significantly faster than that in other systems, and it rapidly expands within 2 h, gradually stabilizes after 6 h, and basically no longer changes in mass after 10 h, and the final swelling ratio is 3. In deionized water and 0.9% NaCl solution, the swelling ratio of the hydrogel is about 1.5 within the first 2 h, and then it quickly enters a saturated state. This proves that the double network hydrogel prepared by the application not only has good structural stability in high ion concentration and urea environment, but also has significant advantages as a cartilage-like substitute material due to its low swelling and long-term stability.

[0026] In summary, by adjusting the molecular weight of the four-arm polyethylene glycol amine and the crosslinking ratio with polyacrylic acid, the double network structure with flexible chain segments and strong interaction is formed, which effectively improves the overall strength and mechanical stability of the material, and also has excellent comprehensive performance such as high mechanical strength, fatigue resistance, self-recovery and anti-swelling performance; It can be widely used in the preparation of materials in the fields of joint cartilage repair, artificial soft tissue replacement, medical cushioning materials and flexible biological devices.

[0027] The above description of the embodiments is only used to help understand the method of the application and its core idea. It should be noted that for those skilled in the art, without departing from the principles of the application, some improvements and modifications can be made to the application, and these improvements and modifications also fall within the protection scope of the claims of the application.

[0028] The above description of the disclosed embodiments enables those skilled in the art to implement or use the application. Various modifications to the embodiments will be apparent 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 application. Therefore, the application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A process for the preparation of a four-armed polyethylene glycol amine, characterized in that, The four-arm polyethylene glycol amine has a molecular weight of 10 kDa or 40 kDa. The preparation steps of the four-arm polyethylene glycol amine with a molecular weight of 10 kDa are as follows: four-arm polyethylene glycol, phthalimide, azodicarboxylic acid diisopropyl ester and triphenylphosphine are subjected to Mitsunobu reaction and hydrazinolysis to obtain the four-arm polyethylene glycol amine with a molecular weight of 10 kDa. The preparation steps of the four-arm polyethylene glycol amine with a molecular weight of 40 kDa are as follows: four-arm polyethylene glycol, triethylamine, methylsulfonyl chloride, phthalimide and azodicarboxylic acid diisopropyl ester are subjected to Mitsunobu reaction and hydrazinolysis to obtain the four-arm polyethylene glycol amine with a molecular weight of 40 kDa.

2. The method for preparing the four-armed polyethylene glycolamine according to claim 1, characterized in that, The preparation steps of the four-arm polyethylene glycol amine with a molecular weight of 10 kDa are as follows: four-arm polyethylene glycol, phthalimide and triphenylphosphine are dissolved in anhydrous tetrahydrofuran, a tetrahydrofuran solution containing azodicarboxylic acid diisopropyl ester is added dropwise, stirring is performed for one week, the solvent is removed, the residue is dissolved and filtered, extraction is performed, the organic phase is dried with anhydrous sodium sulfate, filtration and concentration are performed; the product is precipitated from the organic phase with ether three times to obtain a light yellow powder; the light yellow powder is dissolved in tetrahydrofuran and refrigerated, suction filtration is performed at room temperature, the filter cake is dried, normal hexane is added twice for slurry, suction filtration is performed, and natural air drying is performed to obtain the four-arm polyethylene glycol amine with a molecular weight of 10 kDa; the refrigeration time of the light yellow powder in tetrahydrofuran is 48 h; the molar ratio of the four-arm polyethylene glycol, phthalimide, azodicarboxylic acid diisopropyl ester and triphenylphosphine is 1:5:5:

5.

3. The method for preparing the four-armed polyethylene glycolamine according to claim 1, characterized in that, The preparation steps of the four-arm polyethylene glycol amine with a molecular weight of 40 kDa are as follows: triethylamine and methylsulfonyl chloride are added to a solution of four-arm polyethylene glycol in anhydrous dichloromethane, reaction is performed in an ice bath environment, after the reaction is completed, temperature is increased and stirring is performed, the reaction product is purified by slurry with ether to obtain an intermediate; the intermediate, phthalimide and azodicarboxylic acid diisopropyl ester are dissolved in anhydrous tetrahydrofuran for reaction, the product is dissolved in ethanol, 80% hydrazine hydrate is added, reflux reaction is performed, the crude product is dissolved and filtered, extraction is performed, the organic phase is dried with anhydrous sodium sulfate, filtration and concentration are performed; the product is precipitated from the organic phase with ether three times to obtain a brown powder; the brown powder is dissolved in tetrahydrofuran and refrigerated, suction filtration is performed at room temperature, the filter cake is dried, normal hexane is added twice for slurry, suction filtration is performed, and natural air drying is performed to obtain the four-arm polyethylene glycol amine with a molecular weight of 40 kDa; the molar ratio of the four-arm polyethylene glycol, triethylamine, methylsulfonyl chloride, phthalimide and azodicarboxylic acid diisopropyl ester is 1:4.3:1.3:4.2:

5.

4. The process for preparing a four-armed polyethylene glycol amine according to claim 3, characterized in that, The reaction time in the ice bath environment is 8 h; after the reaction is completed, the temperature is increased to 25℃; the stirring time is 48 h.

5. The method for preparing the four-armed polyethylene glycolamine according to claim 3, characterized in that, The reaction temperature of the intermediate, phthalimide and azodicarboxylic acid diisopropyl ester in anhydrous tetrahydrofuran is 60℃, and the reaction time is 3 days.

6. The method for preparing the four-armed polyethylene glycolamine according to claim 3, characterized in that, The reflux reaction time is 8 h; the refrigeration time of the brown powder in tetrahydrofuran is 48 h.

7. A four-armed polyethylene glycol amine, characterized in that, The preparation method is prepared by the preparation method in any one of claims 1-6.

8. Use of a four-armed polyethylene glycol amine according to claim 7, characterized in that, It is applied to the preparation of cartilage-like materials.

9. Use of a four-armed polyethylene glycol amine according to claim 8, characterized in that, The application relates to a preparation method of a four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel.

10. Use of a four-armed polyethylene glycol amine according to claim 9, characterized in that, The preparation steps of the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel are as follows: S1: adding 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide into a phosphate buffer solution containing four-arm polyethylene glycol amine, stirring, adding polyacrylic acid for reaction to obtain a bottom layer hydrogel material; S2: soaking the bottom layer hydrogel material in a FeCl3 solution, taking out and injecting into a mold, removing air bubbles, and performing a continuous freeze-thaw cycle to obtain the four-arm polyethylene glycol amine-polyacrylic acid double network hydrogel; The molar ratio of the four-arm polyethylene glycol amine and the polyacrylic acid is 1:0.75; the molar ratio of the four-arm polyethylene glycol amine, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide is 1:2.2:2.5.

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