A method for preparing a degradable polyurethane material

Abstract

This invention discloses a method for preparing a biodegradable polyurethane material, comprising the following steps: (1) under an inert atmosphere, decanolide monomer, alcohol initiator and ring-opening polymerization catalyst are mixed, and after reaction, the reaction product is dissolved in an organic solvent and then precipitated in cold methanol, filtered and dried to obtain polydecanolide prepolymer; wherein, the molar ratio of the alcohol initiator to decanolide monomer is 1:100~600; (2) the polydecanolide prepolymer is vacuumed at 20~100℃ for 4~20h, then isocyanate and polycondensation catalyst are added to it, and the reaction is carried out at 20~120℃ for 1~20h to obtain polyurethane precursor; (3) the polyurethane precursor obtained by the reaction, cyclodextrin, organic solvent and catalyst are mixed, and the reaction is carried out at 60~120℃ for 12~24h, and the obtained product is dried to obtain polyurethane material. The polyurethane material of this invention has both good biodegradability and mechanical properties.

Description

Technical Field

[0001] This invention relates to a method for preparing a biodegradable polyurethane material. Background Technology

[0002] Polyurethane (PU) is a high-performance, widely used polymer material produced by the reaction of isocyanates (hard segments) and polyols (soft segments). By adjusting the chemical structure and ratio of the hard and soft segments, a variety of products can be manufactured, ranging from soft sponges to hard plastics, and from highly elastic elastomers to tough coatings. However, currently commercially available polyurethane products mainly rely on non-renewable petroleum-based raw materials, exhibiting poor degradation ability in the natural environment and difficulties in recycling. After use, they are often disposed of through incineration or landfill, easily causing unavoidable environmental pollution problems. The main reasons why petroleum-based polyurethane is difficult to degrade can be summarized in the following three aspects: First, its molecular backbone contains a large number of structurally stable urethane bonds and benzene ring structures, exhibiting high chemical inertness to microorganisms and enzymes; second, although the soft segments composed of petroleum-based polyethers give the material excellent flexibility, they usually lack sensitive functional groups that are easily hydrolyzed or photodegraded; in addition, the dense cross-linked network structure further hinders the penetration and diffusion of degradation media such as water and enzymes.

[0003] To improve the biodegradability of polyurethane materials, existing technologies include developing novel polyols using renewable biomass raw materials or introducing sensitive bonds that are easily hydrolyzed or photodegraded into the molecular chain. However, while improving the biodegradability of polyurethane, these technologies sometimes reduce its mechanical properties (such as strength and toughness), presenting a problem of balancing biodegradability and mechanical properties. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a method for preparing polyurethane materials that simultaneously possess good biodegradability and mechanical properties.

[0005] Technical solution: The preparation method of the biodegradable polyurethane material of the present invention includes the following steps:

[0006] (1) Under an inert atmosphere, decanolide monomer, alcohol initiator and ring-opening polymerization catalyst are mixed. After the reaction, the reaction product is dissolved in an organic solvent and then precipitated in cold methanol. After filtration and drying, polydecanolide prepolymer is obtained. The molar ratio of alcohol initiator to decanolide monomer is 1:100~600. The amount of ring-opening polymerization catalyst is 0.1%~1% of the mass of decanolide monomer.

[0007] (2) The polydecyl lactone prepolymer is vacuumed at 20~100℃ for 4~20h, and then isocyanate and polycondensation catalyst are added to it and reacted at 20~120℃ for 1~20h to obtain polyurethane precursor;

[0008] (3) The polyurethane precursor, cyclodextrin, organic solvent and catalyst obtained by the reaction are mixed and reacted at 60~120℃ for 12~24h. The resulting product is dried in a vacuum oven at 60℃ overnight to obtain a biodegradable polyurethane material.

[0009] In step (1), the decyl lactone monomer is butyl decyl lactone or propyl decyl lactone. The ring-opening polymerization catalyst is one of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, stannous octoate, or NN-dibutylformamide (CAS No. 761-65-9); the alcohol initiator is one of methanol, ethanol, benzyl alcohol, ethylene glycol, terephthalic acid, glycerol, or pentaerythritol. Controlling the molar ratio of alcohol initiator to decyl lactone monomer to 1:100~600 can effectively regulate the molecular weight distribution (3,000~40,800 Da) of polydecyl lactone prepolymer, making its number average molecular weight (M n The catalyst dosage is within a suitable range for subsequent polyurethane synthesis, ensuring that the final polyurethane material possesses excellent mechanical strength and flexibility. The catalyst dosage is controlled at 0.1%~1% of the monomer mass, enabling the reaction to maintain a high reaction rate at room temperature while avoiding the negative impact of residual catalyst on the material's biocompatibility. Dissolving the catalyst in an organic solvent and then precipitating it in cold methanol effectively removes unreacted monomers and catalyst impurities, improving the purity of the prepolymer and laying the foundation for the subsequent synthesis of structurally regular polyurethanes.

[0010] In step (2), the isocyanate is one of hexamethylene diisocyanate, diphenylmethane diisocyanate, or isophorone diisocyanate; the molar ratio of the polydecyl lactone prepolymer to the isocyanate (based on functional groups, it refers to the molar ratio of the terminal hydroxyl groups of the polydecyl lactone prepolymer to the isocyanate groups (-NCO) in the isocyanate being 1:1~10) is 1:1~10. The polycondensation catalyst is at least one of stannous octoate, dibutyltin dilaurate, or 1,4-diazabicyclo[2.2.2]octane, and the amount of the polycondensation catalyst added is 6.25%~8% of the mass of the polydecyl lactone prepolymer. During the reaction, the disappearance of the characteristic peaks of the isocyanate groups is monitored by Fourier transform infrared spectroscopy to determine the reaction endpoint. The polydecyl lactone prepolymer is vacuumed at 20-100°C for 4-20 hours. This treatment can completely remove the adsorbed moisture and volatile small molecules in the prepolymer, effectively preventing moisture from reacting with isocyanate to generate CO2 and causing bubble defects in the material, thus ensuring the integrity of the polyurethane crosslinking structure. Subsequently, isocyanate and catalyst are added, and the reaction is carried out at 20-120°C for 1-20 hours. This temperature range can promote the efficient condensation of isocyanate and polydecyl lactone chain-terminal hydroxyl groups, and inhibit the occurrence of side reactions, forming a three-dimensional network structure with urethane bonds as bridging points, giving the material high tensile strength and elongation at break.

[0011] In step (3), the cyclodextrin is α-cyclodextrin or β-cyclodextrin, and the mass ratio of the polyurethane precursor to the cyclodextrin is 10~15:1. The organic solvent is one of dichloromethane, toluene, tetrahydrofuran, or N,N-dimethylformamide. The catalyst is N,N-dibutylformamide, and the amount of catalyst added is 2%~3% of the mass of the polyurethane precursor.

[0012] The biodegradable polyurethane material obtained by this invention has good biodegradability, biocompatibility, and adjustable mechanical properties. It can be widely used in absorbable implantable medical devices, flexible electronic devices, drug sustained-release and controlled-release systems, additive manufacturing (3D printing) materials, high-end functional coatings, and environmentally friendly packaging materials, etc., and has high application value and industrialization prospects. The biodegradable polyurethane material of this invention has a tensile strength of up to 16.5 MPa and an elongation at break of up to 873.1%. In a controlled composting environment (temperature maintained at 58℃±2℃, with continuous humid air to ensure oxygen concentration is not less than 6%), the decomposition rate is greater than 90%, and the minimum number of days required is 73 days. The complete decomposition time in 1 mol / L NaOH solution is within 60 days. Moreover, the degradation products are mainly water-soluble small molecules with good biocompatibility.

[0013] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0014] (1) This invention uses ring-opening polymerization to prepare biodegradable polyurethane. Compared with traditional polycondensation reaction, no small molecule byproducts are generated during the polymerization process. The reaction conditions are mild, effectively avoiding the impact of high temperature and byproduct residues on material performance and biosafety. At the same time, combined with ring-opening polymerization catalyzed by organic strong base or tin-based metal complex and "dissolution-precipitation" purification process, solvent-free and low-energy reaction is achieved in subsequent polyurethane synthesis, simplifying the process and improving the comprehensive performance of the material. Ring-opening polymerization has good molecular weight and molecular structure controllability, and polymers with narrow molecular weight distribution and well-defined chain end structure can be obtained. The degradation rate and mechanical properties of the material can be precisely controlled, improving the stability and safety of the material in medical and biological applications.

[0015] (2) In this invention, decanolide is selected as an aliphatic lactone monomer and introduced into the polyurethane system. The prepolymer of polydecanolide is constructed by alcohol-initiated ring-opening polymerization. The specific number of initiator functional groups enables the prepolymer to form a linear molecular chain with predictable structure, and the hydroxyl group is located at the chain end, which provides a structural basis for the subsequent reaction with isocyanate to form regular urethane hard segments. By controlling the molar ratio of decanolide to alcohol initiator (100-600:1), the molecular weight of the prepolymer can be precisely controlled, avoiding the processing difficulties caused by excessively high molecular weight or the insufficient mechanical properties caused by excessively low molecular weight. As a flexible soft segment, the long aliphatic chain of polydecanolide gives the material excellent elasticity and flexibility, while the urethane groups formed by isocyanate, as rigid hard segments, can form stable physical cross-linking points through strong intermolecular hydrogen bonding, constructing a clear microphase separation structure, thereby achieving a synergistic improvement in the strength and toughness of the material.

[0016] (3) This invention introduces a star-shaped topological crosslinking structure with β-cyclodextrin as the core. Its abundant hydroxyl groups can not only participate in chain extension and crosslinking reactions as active sites, but also serve as stable multi-arm connection centers, improving the uniformity and stability of crosslinking point distribution within the polymer, effectively restricting molecular chain segment movement, enhancing inter-chain forces and stress transfer efficiency, dispersing and alleviating local stress concentration under external force, and further improving the mechanical strength, modulus and structural stability of the material. At the same time, combined with the ring-opening polymerization catalyzed by organic strong base or tin-based metal complex and the "dissolution-precipitation" purification process, a prepolymer with narrow molecular weight distribution and good end group integrity can be obtained under normal temperature or low temperature conditions, and solvent-free and low-energy reaction can be achieved in the subsequent polyurethane synthesis, simplifying the process and improving the comprehensive performance of the material. Attached Figure Description

[0017] Figure 1 This is a gel permeation chromatogram of the polydecyl lactone prepolymer synthesized in Example 1;

[0018] Figure 2 The above is the 1H NMR spectrum of the polydecyl lactone prepolymer synthesized in Example 1;

[0019] Figure 3 The infrared spectrum of the polyurethane material synthesized in Example 1 is shown below.

[0020] Figure 4 A digital photograph of the polyurethane material synthesized in Example 1;

[0021] Figure 5 The image shows the infrared spectrum of the polyurethane material synthesized in Example 4. Detailed Implementation

[0022] Example 1

[0023] The method for preparing the biodegradable polyurethane material of the present invention includes the following steps:

[0024] (1) Under an inert atmosphere, butylated decyl lactone and terephthalic acid were mixed evenly at a molar ratio of 600:1 (terephthalic acid was 20 mg). Then, 1% by mass of 1,5,7-triazabicyclo[4.4.0]dec-5-ene of monomer (butylated decyl lactone) was added to the mixture. The mixture was reacted at room temperature for 10 hours. After the reaction was terminated, the reaction product was dissolved in an organic solvent (dichloromethane) and then precipitated in cold methanol (-20℃~-60℃). The mixture was filtered, and the solid was dried in a vacuum oven for 48 hours to obtain polydecyl lactone prepolymer.

[0025] (2) Place 1g of polydecyl lactone prepolymer in a reaction flask and evacuate at 20°C for 20h. Then, inject 0.1mL of hexamethylene diisocyanate and 50μL of stannous octoate (commercial model TCI-T3149-500G, CAS number 301-10-0) into the flask. Then, quickly transfer the mixture to a polytetrafluoroethylene mold and react at 100°C for 6h to obtain polyurethane precursor.

[0026] (3) Place 0.4 g of polyurethane precursor in a reaction flask, then add 37.5 mg of β-cyclodextrin, 10 mg of N,N-dibutylformamide as catalysts and 15 mL of DMF (N,N-dimethylformamide) as solvent, react at 60 °C for 24 h, and dry the resulting product in a vacuum oven at 60 °C overnight to obtain biodegradable polyurethane material.

[0027] The reaction equation for preparing polydecyl lactone prepolymer is as follows:

[0028]

[0029] The reaction equation for the synthesis of polyurethane precursors from polydecyl lactone prepolymer and hexamethylene isocyanate is as follows:

[0030]

[0031] The reaction equation for the preparation of polyurethane from polydecyl lactone prepolymer and β-cyclodextrin is as follows:

[0032]

[0033] The analysis was performed using gel permeation chromatography (GPC) based on a Waters-208 analyzer, with tetrahydrofuran as the solvent, an elution rate of 2.0 mL / min, and polystyrene as the standard. Figure 1 It can be seen that the number-average molecular weight of the obtained polydecyl lactone prepolymer is 40743 and the weight-average molecular weight is 46187.

[0034] right Figure 2Spectrum analysis was performed, specifically: ¹H NMR (CDCl₃) δ 0.88 (t, J=6.84 Hz, 293 H), 1.07–1.37 (br, 617 H), 1.37–1.77 (br, 633 H), 2.19–2.39 (m, 216 H), 3.49 (s, 1 H), 3.54–3.64 (m, 2.6 H), 3.68 (s, 1 H), 3.98–4.10 (m, 1.4 H), 4.87 (quin, J= 5.80 Hz, 103 H), 5.11 (s, 4 H), 7.35 (s, 4 H); ¹³C{¹H} NMR (CDCl₃) δ 173.1, 73.7, 34.2, 34.0, 33.5, 31.7, 25.0, 22.6, 20.8, 14.0. (Passed) Figure 3 It can be seen that the present invention successfully synthesized polydecyl lactone prepolymer.

[0035] Figure 3 In the middle, there is no 2250cm. -1 The infrared characteristic peaks on the left and right indicate that the -NCO group has completely reacted. Figure 4 As shown, this is the polyurethane film prepared in Example 1.

[0036] Example 2

[0037] The method for preparing the biodegradable polyurethane material of the present invention includes the following steps:

[0038] (1) Under an inert atmosphere, butylated decyl lactone and terephthalic acid were mixed evenly at a molar ratio of 100:1 (terephthalic acid was 20 mg), and then 1% by mass of 1,5,7-triazabicyclo[4.4.0]dec-5-ene was added. The mixture was reacted at room temperature for 10 hours. After the reaction was terminated, the reaction product was dissolved in an organic solvent (dichloromethane) and then precipitated in cold methanol. The mixture was filtered, and the solid was dried in a vacuum oven for 48 hours to obtain polydecyl lactone prepolymer.

[0039] (2) Place 1g of polydecyl lactone prepolymer in a reaction flask and evacuate at 60°C for 8h. Then inject 0.1mL of hexamethylene diisocyanate and 50μL of 1,4-diazabicyclo[2.2.2]octane into the flask. Then quickly transfer the mixture to a polytetrafluoroethylene mold and react at 20°C for 20h to obtain polyurethane precursor.

[0040] (3) Place 0.4 g of polyurethane precursor in a reaction flask, then add 37.5 mg of β-cyclodextrin, 10 mg of NN-dibutylformamide as catalysts and 15 mL of DMF as solvent, react at 60 °C for 24 h, and dry the resulting product in a vacuum oven at 60 °C overnight to obtain biodegradable polyurethane material.

[0041] Example 3

[0042] The method for preparing the biodegradable polyurethane material of the present invention includes the following steps:

[0043] (1) Under an inert atmosphere, butylated decyl lactone and terephthalic acid were mixed evenly at a molar ratio of 300:1 (terephthalic acid was 20 mg), and then 1% of the monomer mass of stannous octoate was added. The mixture was reacted at room temperature for 15 hours. After the reaction was terminated, the reaction product was dissolved in an organic solvent (dichloromethane) and then precipitated in cold methanol. The mixture was filtered, and the solid was dried in a vacuum oven for 48 hours to obtain polydecyl lactone prepolymer.

[0044] (2) Place 1g of polydecyl lactone prepolymer in a reaction flask, evacuate at 100°C for 4h, then inject 0.1mL of hexamethylene diisocyanate and 50μL of stannous octoate into the flask, and then quickly transfer the mixture to a polytetrafluoroethylene mold and react at 120°C for 1h to obtain polyurethane precursor.

[0045] (3) Place 0.4 g of polyurethane precursor in a reaction flask, then add 37.5 mg of β-cyclodextrin, 10 mg of NN-dibutylformamide as catalysts and 15 mL of DMF as solvent, react at 60 °C for 24 h, and dry the resulting product in a vacuum oven at 60 °C overnight to obtain biodegradable polyurethane material.

[0046] Example 4

[0047] The method for preparing the biodegradable polyurethane material of the present invention includes the following steps:

[0048] (1) Under an inert atmosphere, butylated decyl lactone and benzyl alcohol were mixed evenly at a molar ratio of 300:1 (20 mg benzyl alcohol). Then, 1% by mass of 1,5,7-triazabicyclo[4.4.0]dec-5-ene was added to the mixture. The mixture was reacted at room temperature for 10 hours. After the reaction was terminated, the reaction product was dissolved in an organic solvent (dichloromethane) and then precipitated in cold methanol. The mixture was filtered and the solid was dried in a vacuum oven for 48 hours to obtain polydecyl lactone prepolymer.

[0049] (2) Place 1g of polydecyl lactone prepolymer in a reaction flask, vacuum at 100°C for 4h, then inject 0.1mL of isophorone diisocyanate and 50μL of stannous octoate into the flask, and then quickly transfer the mixture to a polytetrafluoroethylene mold and react at 60°C for 10h to obtain polyurethane precursor.

[0050] (3) Place 0.4 g of polyurethane precursor in a reaction flask, then add 37.5 mg of β-cyclodextrin, 10 mg of NN-dibutylformamide as catalysts and 15 mL of DMF as solvent, react at 60 °C for 24 h, and dry the resulting product in a vacuum oven at 60 °C overnight to obtain biodegradable polyurethane material.

[0051] Figure 5 Middle, 1242cm -1 The formation of the CN bond indicates that the carbamate bond has been formed, and 2250 cm⁻¹ -1 The absence of obvious infrared characteristic peaks nearby indicates that there are no remaining -NCO functional groups, suggesting that the isocyanate has been completely and completely reacted.

[0052] Comparative Example 1 – Compared to Example 1, the prepolymer used in Comparative Example 1 is polyethylene glycol with a molecular weight of 40,000, specifically:

[0053] (1) Place 1g of polyethylene glycol in a reaction flask and evacuate at 20°C for 20h. Then inject 0.1mL of hexamethylene diisocyanate and 50μL of stannous octoate into the flask. Then quickly transfer the mixture to a polytetrafluoroethylene mold and react at 100°C for 6h to obtain a polyurethane precursor.

[0054] (2) Place 0.4 g of polyurethane precursor in a reaction flask, then add 37.5 mg of β-cyclodextrin, 10 mg of NN-dibutylformamide as catalysts and 15 mL of DMF as solvent, react at 60 °C for 24 h, and dry the resulting product in a vacuum oven at 60 °C overnight to obtain biodegradable polyurethane material.

[0055] Comparative Example 2 - The only difference between Comparative Example 2 and Example 1 is that hexamethylene diisocyanate was not added in step (2). Specifically:

[0056] (1) Under an inert atmosphere, butylated decyl lactone and terephthalic acid were mixed evenly at a molar ratio of 600:1 (terephthalic acid was 20 mg), and then 1% by mass of 1,5,7-triazabicyclo[4.4.0]dec-5-ene was added. The mixture was reacted at room temperature for 10 hours. After the reaction was terminated, the reaction product was dissolved in an organic solvent (dichloromethane) and then precipitated in cold methanol. The mixture was filtered, and the solid was dried in a vacuum oven for 48 hours to obtain polydecyl lactone prepolymer.

[0057] (2) Place 1g of polydecyl lactone prepolymer in a reaction flask, evacuate at 20°C for 20h, then add 50μL of stannous octoate to the flask, and then quickly transfer the mixture to a polytetrafluoroethylene mold and react at 100°C for 6h to obtain a gel-like substance.

[0058] Comparative Example 3 - Compared to Example 1, the only difference in Comparative Example 3 is that stannous octoate was not added in step (2), specifically:

[0059] (1) Under an inert atmosphere, butylated decyl lactone and terephthalic acid were mixed evenly at a molar ratio of 600:1 (terephthalic acid was 20 mg), and then 1% by mass of 1,5,7-triazabicyclo[4.4.0]dec-5-ene was added. The mixture was reacted at room temperature for 10 hours. After the reaction was terminated, the reaction product was dissolved in an organic solvent (dichloromethane) and then precipitated in cold methanol. The mixture was filtered, and the solid was dried in a vacuum oven for 48 hours to obtain polydecyl lactone prepolymer.

[0060] (2) Place 1g of polydecyl lactone prepolymer in a reaction flask, evacuate at 20°C for 20h, then inject 0.1mL of hexamethylene diisocyanate into the flask, and then quickly transfer the mixture to a polytetrafluoroethylene mold and react at 100°C for 6h to obtain a gel-like substance.

[0061] Comparative Example 4 – Compared to Example 1, the only difference in Comparative Example 4 is that the ring-opening polymerization catalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene was not added in step (1). Specifically:

[0062] Under an inert atmosphere, butylated decyl lactone and terephthalic acid were mixed at a molar ratio of 600:1 (terephthalic acid 20 mg) and reacted at room temperature for 10 hours. After the reaction was terminated, the reaction product was dissolved in an organic solvent (dichloromethane) and then precipitated in cold methanol. After filtration, the solid was dried in a vacuum oven for 48 hours. Without the addition of a ring-opening polymerization catalyst, the first step reaction did not occur, that is, the polydecyl lactone prepolymer could not be formed.

[0063] Comparative Example 5 - Compared to Example 1, the only difference in Comparative Example 5 is that the alcohol initiator terephthalic acid was not added in step (1). Specifically:

[0064] Under an inert atmosphere, 1 gram of butylated decyl lactone was mixed with 1% by mass of 1,5,7-triazabicyclo[4.4.0]dec-5-ene and reacted at room temperature for 10 hours. After the reaction was terminated, the reaction product was dissolved in an organic solvent (dichloromethane) and then precipitated in cold methanol. After filtration, the solid was dried in a vacuum oven for 48 hours. Polydecyl lactone prepolymer could not be generated without the addition of an alcohol initiator.

[0065] Comparative Example 6 - Compared to Example 1, the only difference in Comparative Example 6 is that in step (1), the alcohol initiator is replaced with butanediol, specifically:

[0066] (1) Under an inert atmosphere, butylated decyl lactone and butanediol were mixed evenly at a molar ratio of 600:1 (butanediol was 20 mg), and then 1% by mass of 1,5,7-triazabicyclo[4.4.0]dec-5-ene of monomer (butylated decyl lactone) was added. The mixture was reacted at room temperature for 10 hours. After the reaction was terminated, the reaction product was dissolved in an organic solvent (dichloromethane) and then precipitated in cold methanol. After filtration, the solid was dried in a vacuum oven for 48 hours to obtain polydecyl lactone prepolymer.

[0067] (2) Place 1g of polydecyl lactone prepolymer in a reaction flask, evacuate at 20°C for 20h, then inject 0.1mL of hexamethylene diisocyanate and 50μL of stannous octoate into the flask, and then quickly transfer the mixture to a polytetrafluoroethylene mold and react at 100°C for 6h to obtain polyurethane precursor.

[0068] (3) Place 0.4 g of polyurethane precursor in a reaction flask, then add 37.5 mg of β-cyclodextrin, 10 mg of N-N-dibutylformamide as catalysts and 15 mL of DMF as solvent, react at 60 °C for 24 h, and dry the resulting product in a vacuum oven at 60 °C overnight to obtain biodegradable polyurethane material.

[0069] Comparative Example 7 - Compared to Example 1, the only difference in Comparative Example 7 is that in step (1), the molar ratio of butylated decyl lactone to terephthalic acid is 900:1, specifically:

[0070] (1) Under an inert atmosphere, butylated decyl lactone and terephthalic acid were mixed evenly at a molar ratio of 900:1 (terephthalic acid was 20 mg). Then, 1% by mass of 1,5,7-triazabicyclo[4.4.0]dec-5-ene of monomer (butylated decyl lactone) was added to the mixture. The mixture was reacted at room temperature for 10 hours. After the reaction was terminated, the reaction product was dissolved in an organic solvent (dichloromethane) and then precipitated in cold methanol. The mixture was filtered and the solid was dried in a vacuum oven for 48 hours to obtain polydecyl lactone prepolymer.

[0071] (2) Place 1g of polydecyl lactone prepolymer in a reaction flask, evacuate at 20°C for 20h, then inject 0.1mL of hexamethylene diisocyanate and 50μL of stannous octoate into the flask, and then quickly transfer the mixture to a polytetrafluoroethylene mold and react at 100°C for 6h to obtain polyurethane precursor.

[0072] (3) Place 0.4 g of polyurethane precursor in a reaction flask, then add 37.5 mg of β-cyclodextrin, 10 mg of N-N-dibutylformamide as catalysts and 15 mL of DMF as solvent, react at 60 °C for 24 h, and dry the resulting product in a vacuum oven at 60 °C overnight to obtain biodegradable polyurethane material.

[0073] Comparative Example 8 - Compared to Example 1, the only difference in Comparative Example 8 is that in step (1), the catalyst for the ring-opening polymerization reaction is diphenyl phosphate, specifically:

[0074] (1) Under an inert atmosphere, butylated decyl lactone and terephthalic acid were mixed evenly at a molar ratio of 600:1 (terephthalic acid was 20 mg), and then 1% by mass of diphenyl phosphate of monomer (butylated decyl lactone) was added. The mixture was reacted at room temperature for 10 hours. After the reaction was terminated, the reaction product was dissolved in an organic solvent (dichloromethane) and then precipitated in cold methanol. The mixture was filtered, and the solid was dried in a vacuum oven for 48 hours to obtain polydecyl lactone prepolymer.

[0075] (2) Place 1g of polydecyl lactone prepolymer in a reaction flask, evacuate at 20°C for 20h, then inject 0.1mL of hexamethylene diisocyanate and 50μL of stannous octoate into the flask, and then quickly transfer the mixture to a polytetrafluoroethylene mold and react at 100°C for 6h to obtain polyurethane precursor.

[0076] (3) Place 0.4 g of polyurethane precursor in a reaction flask, then add 37.5 mg of β-cyclodextrin, 10 mg of N-N-dibutylformamide as catalysts and 15 mL of DMF as solvent, react at 60 °C for 24 h, and dry the resulting product in a vacuum oven at 60 °C overnight to obtain biodegradable polyurethane material.

[0077] Comparative Example 9 - Compared to Example 1, the only difference in Comparative Example 9 is that the "dissolution-precipitation" purification process was not performed in step (1). Specifically:

[0078] (1) Under an inert atmosphere, butylated decyl lactone and terephthalic acid were mixed evenly at a molar ratio of 600:1 (terephthalic acid was 20 mg), and then 1% by mass of 1,5,7-triazabicyclo[4.4.0]dec-5-ene of monomer (butylated decyl lactone) was added. The mixture was reacted at room temperature for 10 hours. After the reaction was terminated, the reaction product was dried in a vacuum oven for 48 hours to obtain polydecyl lactone prepolymer.

[0079] (2) Place 1g of polydecyl lactone prepolymer in a reaction flask, evacuate at 20°C for 20h, then inject 0.1mL of hexamethylene diisocyanate and 50μL of stannous octoate into the flask, and then quickly transfer the mixture to a polytetrafluoroethylene mold and react at 100°C for 6h to obtain polyurethane precursor.

[0080] (3) Place 0.4 g of polyurethane precursor in a reaction flask, then add 37.5 mg of β-cyclodextrin, 10 mg of N-N-dibutylformamide as catalysts and 15 mL of DMF as solvent, react at 60 °C for 24 h, and dry the resulting product in a vacuum oven at 60 °C overnight to obtain biodegradable polyurethane material.

[0081] Comparative Example 10 – Compared to Example 1, the only difference in Comparative Example 10 is that, in step (2), the catalyst for the polycondensation reaction is 1,8-diazabicyclo[5.4.0]undec-7-ene, specifically:

[0082] (1) Under an inert atmosphere, butylated decyl lactone and terephthalic acid were mixed evenly at a molar ratio of 600:1 (terephthalic acid was 20 mg). Then, 1% by mass of 1,5,7-triazabicyclo[4.4.0]dec-5-ene of monomer (butylated decyl lactone) was added to the mixture. The mixture was reacted at room temperature for 10 hours. After the reaction was terminated, the reaction product was dissolved in an organic solvent (dichloromethane) and then precipitated in cold methanol. The mixture was filtered and the solid was dried in a vacuum oven for 48 hours to obtain polydecyl lactone prepolymer.

[0083] (2) Place 1g of polydecyl lactone prepolymer in a reaction flask and evacuate at 20°C for 20h. Then inject 0.1mL of hexamethylene diisocyanate and 50μL of 1,8-diazabicyclo[5.4.0]undec-7-ene into the flask. Then quickly transfer the mixture into a polytetrafluoroethylene mold and react at 100°C for 6h to obtain polyurethane precursor.

[0084] (3) Place 0.4 g of polyurethane precursor in a reaction flask, then add 37.5 mg of β-cyclodextrin, 10 mg of N-N-dibutylformamide as catalysts and 15 mL of DMF as solvent, react at 60 °C for 24 h, and dry the resulting product in a vacuum oven at 60 °C overnight to obtain biodegradable polyurethane material.

[0085] The polydecyl lactone prepolymers in Examples 1-4 were characterized by gel permeation chromatography, and the results are shown in Table 1.

[0086] Table 1 shows the molecular weights of the polydecyl lactone prepolymers in Examples 1-4.

[0087]

[0088] To verify the final aerobic biodegradability of the material of this invention in a controlled composting environment (temperature maintained at 58℃±2℃, with continuous humid air circulation to ensure an oxygen concentration of not less than 6%), tests were conducted according to the national standard GB / T 19277.1-2021 "Determination of Final Aerobic Biodegradability of Plastic Materials under Controlled Composting Conditions". Polyurethane materials from Examples 1-4, Comparative Examples 1-3, and Comparative Examples 6-10 were cut into fragments with a maximum size not exceeding 1cm × 1cm. A certain mass of the sample was weighed, with a dry weight ratio to the inoculum of approximately 1:6. A reference material (microcrystalline cellulose) and a negative control (polyethylene) were prepared as control experiments. The results are shown in Table 2.

[0089] Table 2 shows the test results of the degradability of polyurethane.

[0090]

[0091] Comparative Example 1 uses polyethylene glycol, a polyether polyol, whose molecular weight is similar to that of the resulting polyester. However, due to the easy hydrolysis of ester bonds within the polyester, it degrades more readily. Ether bonds have a higher bond energy than ester bonds, so the polyurethane prepared from polyether polyol degrades less rapidly than that from polyester polyol. Comparative Example 2 did not include isocyanate hard segments, thus failing to generate polyurethane and remaining the original polydecyl lactone prepolymer. In this invention, degradation primarily relies on ester bonds in the polyester soft segments; the faster the degradation, the more polydecyl lactone segments are present. Comparative Example 3 did not include a catalyst for synthesizing the polyurethane prepolymer, thus not generating a polyurethane prepolymer and remaining the original polydecyl lactone prepolymer. In Comparative Example 7, increasing the monomer-to-initiator ratio resulted in a larger molecular weight of the obtained polydecyl lactone prepolymer and a lower degradation rate. In Comparative Example 8, changing the ring-opening polymerization catalyst to diphenyl phosphate resulted in a low monomer conversion rate and a low molecular weight of the obtained polydecyl lactone prepolymer; lower molecular weight generally indicates better degradation performance. In Comparative Example 9, the precipitation-dissolution-sedimentation process was not performed, potentially resulting in unreacted monomers and a reduced degradation rate.

[0092] The biodegradability of the polyurethane material prepared in Example 1 was tested. Fifteen 1cm × 1cm polyurethane films were cut and placed in 20mL sample bottles, and 1mol / L NaOH solution was added. At regular intervals, insoluble substances were removed from the sample bottles, surface moisture was removed, and the samples were weighed. The time and corresponding mass were recorded, and the results are shown in Table 3.

[0093] Table 3 shows the test results of the polyurethane degradation performance based on polydecanoic acid in Example 1.

[0094]

[0095] The biodegradability of the polyurethane material prepared in Comparative Example 1 was tested. Fifteen 1cm × 1cm polyurethane films were cut and placed in 20mL sample bottles, and 1mol / L NaOH solution was added. At regular intervals, insoluble substances were removed from the sample bottles, surface moisture was removed, and the samples were weighed. The time and corresponding mass were recorded, and the results are shown in Table 4.

[0096] Table 4 shows the test results of the biodegradability of polyurethane based on polyethylene glycol in Comparative Example 1.

[0097]

[0098] As can be seen from the comparison between Example 1 and Comparative Example 1, the biodegradable polyurethane material of the present invention has better degradation performance and can be degraded into water-soluble small molecules after a certain period of time.

[0099] The biodegradable polyurethane materials prepared in Examples 1-4, Comparative Examples 1-3, and Comparative Examples 6-10 were subjected to tensile property testing. The mechanical properties of the materials were examined using an electronic universal testing machine. The tensile properties were tested according to the Chinese national standard GB / T 528-2009, with a tensile rate of 25 mm / min. The results are shown in Table 5.

[0100] Table 5 lists the biodegradable polyurethane materials prepared in Examples 1-4, Comparative Examples 1-3, and Comparative Examples 6-10.

[0101] Tensile property test results

[0102]

[0103] The tensile data from Examples 1-4, Comparative Examples 1-3, and Comparative Examples 6-10 show that polyurethanes based on polydecyl lactone possess superior degradation performance, along with good tensile strength and elongation at break. In Comparative Example 2, no isocyanate hard segments were added, and no polyurethane was formed; the tensile strength was supported only by the soft segments, resulting in low tensile strength and low elongation at break. In Comparative Example 3, no catalyst was added for synthesizing the polyurethane prepolymer, and no polyurethane prepolymer was formed; the tensile strength was supported only by the soft segments, resulting in low tensile strength and low elongation at break. In Comparative Example 8, after changing the catalyst for ring-opening polymerization to diphenyl phosphate, the monomer conversion rate was low, resulting in a low molecular weight polydecyl lactone prepolymer and decreased mechanical properties.

Claims

1. A method for preparing a biodegradable polyurethane material, characterized in that, Includes the following steps: (1) Under an inert atmosphere, decanolide monomer, alcohol initiator and ring-opening polymerization catalyst are mixed. After the reaction, the reaction product is dissolved in an organic solvent and then precipitated in cold methanol. After filtration and drying, polydecanolide prepolymer is obtained. The molar ratio of alcohol initiator to decanolide monomer is 1:100~600. The decanolide monomer is butyldecanolide or propyldecanolide. The ring-opening catalyst is 1,5,7-triazabicyclo[4.4.0]dec-5-ene or stannous octoate. The alcohol initiator is benzyl alcohol or terephthalic acid. (2) The polydecyl lactone prepolymer is vacuumed at 20~100℃ for 4~20h, and then isocyanate and polycondensation catalyst are added to it, and the reaction is carried out at 20~120℃ for 1~20h to obtain polyurethane precursor; the polycondensation catalyst is at least one of stannous octoate, dibutyltin dilaurate or 1,4-diazabicyclo[2.2.2]octane, and the amount of the polycondensation catalyst added is 6.25%~8% of the mass of the polydecyl lactone prepolymer; (3) The polyurethane precursor, cyclodextrin, organic solvent and catalyst obtained by the reaction are mixed and reacted at 60~120℃ for 12~24h. The resulting product is dried to obtain a biodegradable polyurethane material. The catalyst is NN-dibutylformamide and the amount of catalyst added is 2%~3% of the mass of the polyurethane precursor.

2. The preparation method according to claim 1, characterized in that: In step (1), the number average molecular weight of the polydecyl lactone prepolymer is 3,000~40,800 Da.

3. The preparation method according to claim 1, characterized in that: In step (1), the amount of the ring-opening polymerization catalyst used is 0.1% to 1% of the mass of the decanolide monomer.

4. The preparation method according to claim 1, characterized in that: In step (2), the isocyanate is one of hexamethylene diisocyanate, diphenylmethane diisocyanate or isophorone diisocyanate; the molar ratio of the polydecyl lactone prepolymer to the isocyanate is 1:1~10.

5. The preparation method according to claim 1, characterized in that: In step (3), the cyclodextrin is α-cyclodextrin or β-cyclodextrin, and the mass ratio of the polyurethane precursor to the cyclodextrin is 10~15:1; the organic solvent is one of dichloromethane, toluene, tetrahydrofuran or N,N-dimethylformamide.

6. The preparation method according to claim 1, characterized in that: In step (3), the drying temperature is 60~80℃ and the drying time is not less than 12h.

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