Bioabsorbable copolymer material and preparation method thereof

Abstract

The present invention provides a bioabsorbable copolymer material, comprising: vegetable oil-based cyclocarbonate, polylactic acid and nano-hydroxyapatite particles. Calculated by mass percentage, the vegetable oil-based cyclocarbonate accounts for 20-40%, the nano-hydroxyapatite particles account for 10-30%, and the balance is polylactic acid. The bioabsorbable copolymer material is used to fill and repair bone defects caused by trauma, bone tumor resection or other diseases, and can be used as a bone transplant material to replace autologous bone or allogeneic bone transplantation, gradually degrade in the body, and promote the formation of new bone, and finally be completely replaced by new bone tissue. The bioabsorbable copolymer material has a stable composite structure, which significantly improves the mechanical properties of the material. Nanoparticles with small particle size can more effectively fill the pores in the matrix material, reduce defects, and improve the overall strength and durability of the material.

Description

Technical Field

[0001] The invention belongs to the technical field of bioabsorbable materials, and in particular relates to a bioabsorbable copolymer material and a preparation method thereof. Background Art

[0002] Bioresorbable materials have a wide range of applications in the medical and biomedical fields. They can be used as medical devices and prostheses because they can gradually degrade and be absorbed in the body. Common bioresorbable materials are high molecular polymers such as polyamide, polyethylene oxide, and polyglycolic acid, which can be used for tissue scaffolds or sutures.

[0003] However, in order to meet the requirements of biocompatibility and mechanical strength for bone defect prostheses, metal materials such as titanium and tantalum are usually used in related technologies. However, metal materials are not bioresorbable. Long-term use will cause stress to concentrate in the bones around the prosthesis, reducing the normal load on the bones and even affecting the natural growth and healing of bone tissue. The mechanical strength of ordinary bioresorbable materials is insufficient to meet the needs of bone tissue prostheses. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a bioabsorbable copolymer material and a preparation method thereof, aiming to solve the problem that the bioabsorbable material is insufficient in strength and cannot meet the needs of bone tissue prosthesis.

[0005] To solve the above technical problems, the present invention is implemented as follows: a bioabsorbable copolymer material comprises: plant oil-based cyclic carbonate, polylactic acid and nano-hydroxyapatite particles. Calculated by mass percentage, the plant oil-based cyclic carbonate accounts for 20-40%, the nano-hydroxyapatite particles account for 10-30%, and the balance is the polylactic acid.

[0006] In some embodiments of the present invention, the particle size of the nano-hydroxyapatite particles is 10-20 nm.

[0007] The present invention also provides a preparation method for preparing the bioabsorbable copolymer material as described above, the preparation method comprising the steps of:

[0008] S1. In an inert gas atmosphere, L-lactic acid and D-lactic acid are added into a reaction kettle, and a polycondensation catalyst is added to carry out a first polycondensation reaction to obtain a polylactic acid prepolymer;

[0009] S2, mixing the polylactic acid prepolymer, the vegetable oil-based cyclocarbonate monomer and the components for making the nano-hydroxyapatite particles, adding a copolymerization catalyst to carry out copolymerization reaction, and obtaining a copolymer matrix;

[0010] S3, dissolving and stirring the mixture of the copolymer matrix and nano-hydroxyapatite particles, and sequentially performing precipitation, filtering, and washing steps, and vacuum drying to obtain the bioabsorbable copolymer material.

[0011] In some embodiments of the present invention, step S2 includes:

[0012] S2.1, mixing the polylactic acid prepolymer and the vegetable oil-based cyclocarbonate monomer according to a certain proportion;

[0013] S2.2, adding a mixed solution of calcium nitrate and triethyl phosphate, wherein the molar ratio of calcium to phosphorus is 1.67;

[0014] S2.3, adding a copolymerization catalyst to carry out a copolymerization reaction at 160-220° C. to obtain a mixture of a copolymer matrix and nano-hydroxyapatite particles.

[0015] In some embodiments of the present invention, the copolymerization catalyst includes at least one of zinc acetylacetonate, zinc di(ethylhexanoate), and zinc oxide.

[0016] In some embodiments of the present invention, the polycondensation catalyst includes at least one of stannous octoate, stannous chloride, and dibutyltin dilaurate.

[0017] In some embodiments of the present invention, before step S2, the method further includes:

[0018] The vegetable oil is mixed with an organic solvent, and an epoxidation reagent is added to perform a dropwise reaction, and the epoxidized vegetable oil is obtained after washing;

[0019] The epoxidized vegetable oil is dissolved and carbon dioxide gas is introduced, and a carbonic acid reaction catalyst is added to obtain a vegetable oil-based cyclic carbonate mixture;

[0020] The vegetable oil-based cyclic carbonate mixture is subjected to reduced pressure distillation to remove impurities, thereby obtaining a vegetable oil-based cyclic carbonate monomer.

[0021] In some embodiments of the present invention, the epoxidation reagent includes at least one of a peracetic acid solution, a mixed solution of hydrogen peroxide and glacial acetic acid, and m-chloroperbenzoic acid;

[0022] The reaction temperature of the dropwise addition reaction is 50-70°C, and the reaction time is 4-8h;

[0023] The carbonation reaction catalyst includes at least one of triethylamine and ammonium chloride.

[0024] In some embodiments of the present invention, after step S3, the method further includes:

[0025] Calculating the theoretical density of the bioabsorbable copolymer material by the mass percentage values ​​of the polylactic acid prepolymer, the vegetable oil-based cyclocarbonate monomer, and the nano-hydroxyapatite particles;

[0026] Determining the actual density of the bioabsorbable copolymer material and calculating the porosity;

[0027] Determining whether the porosity satisfies a preset range;

[0028] If it is satisfied, it is marked as good product. If it is not satisfied, it is marked as defective product and the reaction conditions are adjusted.

[0029] In some embodiments of the present invention, the calculation formula of the theoretical density is: ,in, is the theoretical density, is the mass percentage of the component, is the density of the component;

[0030] The porosity calculation formula is: ,in, is the actual density;

[0031] The formula for adjusting the reaction conditions is , ,in, is the adjusted reaction time, is the reaction time before adjustment, is the coefficient of variation of the reaction time, is the difference between the porosity and the average value of the preset range, is the adjusted reaction temperature, is the reaction temperature before adjustment, is the coefficient of variation of the reaction temperature.

[0032] Compared with the prior art, the bioabsorbable copolymer material and the preparation method and composition thereof in the present invention have the following beneficial effects:

[0033] The invention provides a bioabsorbable copolymer material, comprising: plant oil-based cyclocarbonate, polylactic acid and nano-hydroxyapatite particles, wherein the plant oil-based cyclocarbonate accounts for 20-40%, the nano-hydroxyapatite particles account for 10-30%, and the balance is polylactic acid, calculated by mass percentage. The plant oil-based cyclocarbonate and the polylactic acid are both derived from bio-based raw materials and have good biocompatibility and bioabsorbability. They are degraded into non-toxic small molecule compounds in the body and do not cause immune reactions or other biological rejection reactions. The nano-hydroxyapatite particles are the main components of natural bone minerals, have excellent biocompatibility and osteoconductivity, and are conducive to the combination and growth of the bioabsorbable copolymer material with bone tissue. The nano-hydroxyapatite particles can be more evenly dispersed in the matrix of polylactic acid and plant oil-based cyclocarbonate to form a more stable composite structure, significantly improving the mechanical properties of the material, and the nano-particles with small particle size can more effectively fill the pores in the matrix material, reduce defects, and improve the overall strength and durability of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic flow chart of a method for preparing a bioabsorbable copolymer material in one embodiment of the present invention;

[0035] Figure 2 is a detailed flow chart of step S2;

[0036] Figure 3 1 is a schematic flow chart of step S4 of a method for preparing a bioabsorbable copolymer material in one embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0038] The invention provides a bioabsorbable copolymer material, comprising: plant oil-based cyclocarbonate, polylactic acid and nano-hydroxyapatite particles. Calculated by mass percentage, the plant oil-based cyclocarbonate accounts for 20-40%, the nano-hydroxyapatite particles account for 10-30%, and the balance is polylactic acid.

[0039] Both vegetable oil-based cyclic carbonate and polylactic acid are derived from bio-based raw materials and have good biocompatibility and bioabsorbability. They are degraded into non-toxic small molecule compounds in the body and will not cause immune response or other biological rejection reactions. Nano-hydroxyapatite particles are the main component of natural bone minerals and have excellent biocompatibility and osteoconductivity, which helps the bioabsorbable copolymer material to combine with and grow with bone tissue.

[0040] Bioresorbable copolymer materials are used to fill and repair bone defects caused by trauma, bone tumor resection or other diseases. They can be used as bone transplant materials to replace autologous bone or allogeneic bone transplants, avoiding the problems of insufficient donor bone and immune rejection. They gradually degrade in the body while promoting the formation of new bone, and are eventually completely replaced by new bone tissue. Nano-hydroxyapatite particles can be more evenly dispersed in the polylactic acid and vegetable oil-based cyclocarbonate matrix to form a more stable composite structure, significantly improving the mechanical properties of the material, such as compressive strength and flexural strength. Small-sized nanoparticles can more effectively fill the pores in the matrix material, reduce defects, and improve the overall strength and durability of the material.

[0041] Specifically, the particle size of nanohydroxyapatite particles is 10~20nm. Nano-sized hydroxyapatite is similar to natural minerals in bone tissue, and can better interact with surrounding bone cells, promote cell adhesion, proliferation and differentiation, thereby enhancing biocompatibility. Nano-sized hydroxyapatite can simulate the nanostructure of natural bone, provide a microenvironment similar to natural bone tissue, and facilitate the attachment and growth of bone cells. Nano-hydroxyapatite particles with a particle size of 10~20 nanometers can better promote bone conductivity, accelerate the formation and mineralization process of new bone, and contribute to the rapid repair of bone defects.

[0042] The addition of nano-hydroxyapatite particles not only improves the mechanical properties of the material, but also regulates the degradation rate of the material. Smaller particle size can accelerate its degradation rate in the body, and work together with the matrix material to provide a controllable degradation rate to meet the needs of different bone repair applications.

[0043] Nano-hydroxyapatite particles also have antibacterial properties to a certain extent, which can inhibit the growth of bacteria, reduce the risk of infection, and help improve the safety and reliability of bone repair materials.

[0044] Embodiment 1:

[0045] Please refer to Figure 1 Embodiment 1 of the present invention provides a preparation method for preparing a bioabsorbable copolymer material, and the steps of the preparation method include:

[0046] S1. In an inert gas atmosphere, L-lactic acid and D-lactic acid are added into a reaction kettle, and a polycondensation catalyst is added to carry out a first polycondensation reaction to obtain a polylactic acid prepolymer.

[0047] Among them, the mass of L-lactic acid is 25g, the mass of D-lactic acid is 25g, and the polycondensation catalyst is 0.25g of 0.5mol / L stannous octoate solution. In other embodiments, the mass ratio of D-lactic acid to L-lactic acid can be 1:1~2. More L-lactic acid can increase the crystallinity of polylactic acid, making the mechanical strength of the bioabsorbable polymer material stronger. Overall, the mass of L-lactic acid and D-lactic acid is similar to maintain stable performance.

[0048] Polylactic acid is a biodegradable material that degrades into non-toxic lactic acid in the body. It has good biocompatibility and is suitable for various biomedical applications. Polylactic acid with good stereoregularity has higher crystallinity and better mechanical properties. The polycondensation reaction conditions can accurately control the molecular weight and molecular weight distribution of the polylactic acid prepolymer. The higher the molecular weight, the better the mechanical properties and thermal stability of the polylactic acid. The degradation rate of the final material can also be adjusted. Higher molecular weight and more regular stereostructure will slow down the degradation rate, which is suitable for applications that require long-term support.

[0049] Carrying out polycondensation reaction under inert gas atmosphere can effectively avoid the interference of oxygen and moisture on the reaction, improve reaction efficiency, reduce the occurrence of side reactions, and ensure a higher polymerization yield. Inert gas environment and appropriate catalyst can reduce the introduction of impurities, ensure the high purity of polylactic acid prepolymer, and facilitate the subsequent copolymerization reaction and optimization of material properties.

[0050] The steps for preparing the vegetable oil-based cyclic carbonate monomer are as follows:

[0051] The vegetable oil is mixed with an organic solvent, and an epoxidation reagent is added thereto for dropwise reaction, and the epoxidized vegetable oil is obtained after washing.

[0052] The vegetable oil is 15g of olive oil, the organic solvent is 9g of toluene, and the epoxidation reagent is 6g of peracetic acid solution. The reaction temperature of the dropwise reaction is 70°C and the reaction time is 4h. The epoxidation process introduces epoxy groups (-COC-), which are highly reactive and can be copolymerized with other polymer materials to form materials with excellent mechanical properties. These new materials usually have better tensile strength, ductility and wear resistance. The epoxy groups in the epoxidized vegetable oil can be more easily decomposed in a biological environment.

[0053] By adding dropwise, the addition rate of the epoxidation reagent can be precisely controlled, thereby controlling the reaction rate. This helps to avoid violent heat release and side reactions caused by too fast a reaction. The dropwise reaction can avoid violent reactions and heat release caused by adding a large amount of reactants at one time, reducing the danger of the reaction and improving the safety of the operation. During the dropwise addition process, the epoxidation reagent is gradually added to the reaction system to ensure that it is evenly dispersed in the reaction mixture. This helps to improve the reaction efficiency and the uniformity of the product.

[0054] The epoxidized vegetable oil is dissolved and carbon dioxide gas is introduced, and a carbonic acid reaction catalyst is added to obtain a vegetable oil-based cyclic carbonate mixture.

[0055] Epoxidized vegetable oil was dissolved in ethyl acetate, and the carbonation reaction catalyst was 1.5 g of triethylamine. The characteristic absorption peaks of the conversion of epoxy groups to cyclic carbonates were observed by FTIR monitoring. The characteristic chemical shift changes of cyclic carbonates were detected by ¹HNMR and ¹³CNMR. The chemical shift of the epoxy groups in the epoxidized vegetable oil will change with the formation of cyclic carbonates, generating new chemical shift peaks.

[0056] Carbonation reaction catalysts can efficiently catalyze the reaction of epoxidized vegetable oil with carbon dioxide to form cyclic carbonates. Triethylamine is an effective alkaline catalyst that can accelerate the reaction rate and improve the product yield. This method uses carbon dioxide as a raw material and converts it into high-value-added cyclic carbonates, realizing the resource utilization of carbon dioxide, conforming to the concept of green chemistry, and helping to reduce greenhouse gas emissions and environmental pollution.

[0057] The vegetable oil-based cyclic carbonate mixture is subjected to reduced pressure distillation to remove impurities, thereby obtaining a vegetable oil-based cyclic carbonate monomer.

[0058] S2. Mixing the polylactic acid prepolymer, the vegetable oil-based cyclocarbonate monomer and the components for making the nano-hydroxyapatite particles, adding a copolymerization catalyst to carry out copolymerization reaction, and obtaining a copolymer matrix; wherein the copolymerization catalyst is 3.9 g of zinc acetylacetonate.

[0059] Please refer to Figure 2 Specifically, the steps of step S2 are as follows:

[0060] S2.1. Mix polylactic acid prepolymer and vegetable oil-based cyclocarbonate monomer according to a certain proportion.

[0061] S2.2, then add a mixed solution of calcium nitrate and triethyl phosphate, wherein the molar ratio of calcium element to phosphorus element is 1.67.

[0062] S2.3, adding a copolymerization catalyst and performing a copolymerization reaction at 220° C. to obtain a mixture of a copolymerization matrix and nano-hydroxyapatite particles. The mass of the prepared nano-hydroxyapatite particles is 22.5 g.

[0063] The preparation of nano-hydroxyapatite particles uses an in-situ synthesis method. In the in-situ synthesis, the reactants react directly in the target system to generate products without introducing them from the outside. In-situ synthesis can achieve uniform dispersion of nanoparticles in the polymer matrix, avoiding the problem of particle agglomeration caused by external additions. The interface between the nano-hydroxyapatite particles and the matrix is ​​more tightly bonded, which can significantly improve the mechanical properties and functional characteristics of the composite material. The pretreatment and dispersion steps of the external nano-hydroxyapatite particles are reduced, making the entire preparation process simpler and more efficient.

[0064] S3, dissolving and stirring the mixture of the copolymer matrix and the nano-hydroxyapatite particles, and sequentially performing precipitation, filtering, and washing steps, and vacuum drying to obtain a bioabsorbable copolymer material.

[0065] After the copolymer matrix is ​​mixed with the nano-hydroxyapatite particles, the steps of dissolving, stirring, precipitating, filtering, washing and vacuum drying are performed, so that the material has good uniformity and stability and the processing performance of the material is improved.

[0066] Please refer to Figure 3 Furthermore, different bone tissues have different densities. In order to make the bioabsorbable copolymer material better meet the requirements of bone tissue repair, it is necessary to perform density analysis on the bioabsorbable copolymer material to screen out the bioabsorbable copolymer material that meets the requirements of the bone tissue to be repaired. The steps are as follows:

[0067] Step S4.1, calculating the theoretical density of the bioabsorbable copolymer material by the mass percentage values ​​of the polylactic acid prepolymer, the vegetable oil-based cyclocarbonate monomer, and the nano-hydroxyapatite particles.

[0068] The calculation formula of theoretical density is: ,in, is the theoretical density, is the mass percentage of the component, is the density of the component. The density of polylactic acid is 1.25 g / cm³, the density of vegetable oil-based cyclocarbonate is 1.1 g / cm³, and the density of nanohydroxyapatite is 3.16 g / cm³. In Example 1, 1.587.

[0069] Step S4.2, determine the actual density of the bioabsorbable copolymer material and calculate the porosity. Use a gas pycnometer (such as a helium pycnometer) to measure the gas displacement volume of the bioabsorbable copolymer material sample to calculate the density. The calculation formula for the porosity is: ,in, is the actual density.

[0070] Step S4.3, determine whether the porosity meets the preset range; if so, execute step S4.4, if not, execute step S4.5. Porosity affects the degradation rate of the material in the organism. Appropriate porosity can accelerate the degradation of the material and help the growth and repair of new tissues. Porosity affects the biocompatibility and cell adhesion ability of the material. Appropriate porosity can promote the attachment and proliferation of cells on the surface of the material, which is beneficial to tissue engineering applications. The preset range is 60%~70%.

[0071] Step S4.4: Mark as good product.

[0072] Step S4.5, marking as defective and adjusting the reaction conditions. After adjusting the reaction conditions, the bioabsorbable copolymer material is prepared again.

[0073] The formula for adjusting the reaction conditions is , ,in, is the adjusted reaction time, is the reaction time before adjustment, is the coefficient of variation of the reaction time, is the difference between the porosity and the average value of the preset range, is the adjusted reaction temperature, is the reaction temperature before adjustment, is the coefficient of variation of the reaction temperature.

[0074] By adjusting the reaction time and reaction temperature, the porosity of the material can be precisely controlled to reach the desired range and characteristics, thereby ensuring the consistency and quality of the product. Adjusting the reaction conditions to control the porosity helps to optimize the mechanical properties, biocompatibility and degradation rate of the material, making it more suitable for specific application requirements. For example, bone repair materials require appropriate porosity to promote cell attachment and tissue growth.

[0075] For example, is 0.05, is 0.02.

[0076] Through strict control and testing of porosity, the quality consistency and stability of bioresorbable copolymer materials can be ensured, and the impact of quality fluctuations on product performance can be avoided. By adjusting the reaction conditions, the porosity of the material can be optimized to achieve the best mechanical properties and biocompatibility to meet specific application requirements, especially in areas such as bone repair that have strict requirements on porosity. Through automated porosity testing and reaction condition adjustment mechanisms, production efficiency and yield can be improved, scrap rate can be reduced, and production costs can be reduced.

[0077] Embodiment 2:

[0078] Embodiment 2 of the present invention provides a preparation method for preparing a bioabsorbable copolymer material, and the steps of the preparation method include:

[0079] S1. In an inert gas atmosphere, L-lactic acid and D-lactic acid are added into a reaction kettle, and a polycondensation catalyst is added to carry out a first polycondensation reaction to obtain a polylactic acid prepolymer.

[0080] The mass of L-lactic acid was 5 g, the mass of D-lactic acid was 5 g, and the polycondensation catalyst was 0.15 g of a 0.3 mol / L stannous chloride solution.

[0081] The steps for preparing the vegetable oil-based cyclic carbonate monomer are as follows:

[0082] The vegetable oil and the organic solvent are mixed, and an epoxidation reagent is added for dropwise reaction, and the epoxidized vegetable oil is obtained after washing. The vegetable oil is 4.286 g of linseed oil, the organic solvent is 2.571 g of toluene, and the epoxidation reagent is 1.714 g of a mixed solution of hydrogen peroxide and glacial acetic acid. The reaction temperature of the dropwise reaction is 60° C., and the reaction time is 5 h.

[0083] The epoxidized vegetable oil is dissolved and carbon dioxide gas is introduced, and a carbonic acid reaction catalyst is added to obtain a vegetable oil-based cyclic carbonate mixture. The epoxidized vegetable oil is dissolved in ethyl acetate, and the carbonic acid reaction catalyst is 0.4285 g of triethylamine.

[0084] The vegetable oil-based cyclic carbonate mixture is subjected to reduced pressure distillation to remove impurities, thereby obtaining a vegetable oil-based cyclic carbonate monomer.

[0085] S2. Mixing the polylactic acid prepolymer, the vegetable oil-based cyclocarbonate monomer and the components for making the nano-hydroxyapatite particles, adding a copolymerization catalyst to carry out copolymerization reaction, and obtaining a copolymer matrix; wherein the copolymerization catalyst is 3.8 g of zinc di(ethylhexanoate).

[0086] Specifically, the steps of step S2 are as follows:

[0087] S2.1. Mix polylactic acid prepolymer and vegetable oil-based cyclocarbonate monomer according to a certain proportion.

[0088] S2.2, then add a mixed solution of calcium nitrate and triethyl phosphate, wherein the molar ratio of calcium element to phosphorus element is 1.67.

[0089] S2.3, adding a copolymerization catalyst and performing a copolymerization reaction at 220° C. to obtain a mixture of a copolymerization matrix and nano-hydroxyapatite particles. The mass of the prepared nano-hydroxyapatite particles is 2.14 g.

[0090] S3, dissolving and stirring the mixture of the copolymer matrix and the nano-hydroxyapatite particles, and sequentially performing precipitation, filtering, and washing steps, and vacuum drying to obtain a bioabsorbable copolymer material.

[0091] Step S4.1, calculating the theoretical density of the bioabsorbable copolymer material by the mass percentage values ​​of the polylactic acid prepolymer, the vegetable oil-based cyclocarbonate monomer, and the nano-hydroxyapatite particles.

[0092] The calculation formula of theoretical density is: ,in, is the theoretical density, is the mass percentage of the component, is the density of the component. The density of polylactic acid is 1.25 g / cm³, the density of vegetable oil-based cyclocarbonate is 1.1 g / cm³, and the density of nanohydroxyapatite is 3.16 g / cm³. In Example 1, 1.381.

[0093] Step S4.2, determine the actual density of the bioabsorbable copolymer material and calculate the porosity. The calculation formula of the porosity is: ,in, is the actual density.

[0094] Step S4.3, determine whether the porosity meets the preset range; if so, execute step S4.4; if not, execute step S4.5.

[0095] Step S4.4: Mark as good product.

[0096] Step S4.5, marking as defective and adjusting the reaction conditions. After adjusting the reaction conditions, the bioabsorbable copolymer material is prepared again.

[0097] Embodiment 3:

[0098] Embodiment 3 of the present invention provides a preparation method for preparing a bioabsorbable copolymer material, and the steps of the preparation method include:

[0099] S1. In an inert gas atmosphere, L-lactic acid and D-lactic acid are added into a reaction kettle, and a polycondensation catalyst is added to carry out a first polycondensation reaction to obtain a polylactic acid prepolymer.

[0100] The mass of L-lactic acid is 150 g, the mass of D-lactic acid is 130 g, and the polycondensation catalyst is 2 g of a 0.3 mol / L dibutyltin dilaurate solution.

[0101] The steps for preparing the vegetable oil-based cyclic carbonate monomer are as follows:

[0102] The vegetable oil and the organic solvent are mixed, and an epoxidation reagent is added for dropwise reaction, and the epoxidized vegetable oil is obtained after washing. The vegetable oil is 46.665 g of palm oil, the organic solvent is 28 g of isopropanol, and the epoxidation reagent is 18.666 g of m-chloroperoxybenzoic acid solution. The reaction temperature of the dropwise reaction is 50° C., and the reaction time is 6 h.

[0103] The epoxidized vegetable oil is dissolved and carbon dioxide gas is introduced, and a carbonic acid reaction catalyst is added to obtain a vegetable oil-based cyclic carbonate mixture. The epoxidized vegetable oil is dissolved in ethyl acetate, and the carbonic acid reaction catalyst is 4.6665 g of ammonium chloride.

[0104] The vegetable oil-based cyclic carbonate mixture is subjected to reduced pressure distillation to remove impurities, thereby obtaining a vegetable oil-based cyclic carbonate monomer.

[0105] S2. Mixing the polylactic acid prepolymer, the vegetable oil-based cyclocarbonate monomer and the components for making the nano-hydroxyapatite particles, adding a copolymerization catalyst to carry out copolymerization reaction, and obtaining a copolymer matrix; wherein the copolymerization catalyst is 8 g of zinc acetylacetonate.

[0106] Specifically, the steps of step S2 are as follows:

[0107] S2.1. Mix polylactic acid prepolymer and vegetable oil-based cyclocarbonate monomer according to a certain proportion.

[0108] S2.2, then add a mixed solution of calcium nitrate and triethyl phosphate, wherein the molar ratio of calcium element to phosphorus element is 1.67.

[0109] S2.3, adding a copolymerization catalyst and performing a copolymerization reaction at 220° C. to obtain a mixture of a copolymerization matrix and nano-hydroxyapatite particles. The mass of the prepared nano-hydroxyapatite particles is 93.33 g.

[0110] S3, dissolving and stirring the mixture of the copolymer matrix and the nano-hydroxyapatite particles, and sequentially performing precipitation, filtering, and washing steps, and vacuum drying to obtain a bioabsorbable copolymer material.

[0111] Step S4.1, calculating the theoretical density of the bioabsorbable copolymer material by the mass percentage values ​​of the polylactic acid prepolymer, the vegetable oil-based cyclocarbonate monomer, and the nano-hydroxyapatite particles.

[0112] The calculation formula of theoretical density is: ,in, is the theoretical density, is the mass percentage of the component, is the density of the component. The density of polylactic acid is 1.25 g / cm³, the density of vegetable oil-based cyclocarbonate is 1.1 g / cm³, and the density of nanohydroxyapatite is 3.16 g / cm³. In Example 1, 1.778.

[0113] Step S4.2, determine the actual density of the bioabsorbable copolymer material and calculate the porosity. The calculation formula of the porosity is: ,in, is the actual density.

[0114] Step S4.3, determine whether the porosity meets the preset range; if so, execute step S4.4; if not, execute step S4.5.

[0115] Step S4.4: Mark as good product.

[0116] Step S4.5, marking as defective and adjusting the reaction conditions. After adjusting the reaction conditions, the bioabsorbable copolymer material is prepared again.

[0117] Comparative Example 1: Based on Example 1, step S2 is replaced by directly mixing polylactic acid prepolymer, vegetable oil-based cyclocarbonate and nano-hydroxyapatite particles.

[0118] Experiment 1: Measurement of the actual density of the bioresorbable copolymer material.

[0119] Table 1. Experiment 1 data.

[0120]

[0121] According to the above Table 1, the porosity of Comparative Example 1 is significantly lower than that of Examples 1-3. Since Comparative Example 1 does not use an in-situ synthesis method, the nano-hydroxyapatite particles agglomerate, resulting in an uneven density distribution inside the bioabsorbable copolymer material, and the increase in density may cause stress concentration and reduce the overall mechanical properties of the material, such as tensile strength and compressive strength. Agglomerated particles may cause excessive density of the material in a local area, affecting the biocompatibility of the material. In medical applications, this may cause tissue reaction or inflammatory reaction, which is not conducive to the implantation and application of the material. Particle agglomeration will affect the pore structure inside the material, resulting in a decrease in porosity. This will affect the permeability and cell permeability of the material, which is not conducive to cell growth and nutrient transfer in tissue engineering applications.

[0122] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A preparation method, characterized in that: For preparing a bioabsorbable copolymer material, the preparation method comprises the following steps: S1. In an inert gas atmosphere, L-lactic acid and D-lactic acid are added into a reaction kettle, and a polycondensation catalyst is added to carry out a first polycondensation reaction to obtain a polylactic acid prepolymer; S2, mixing the polylactic acid prepolymer, the vegetable oil-based cyclocarbonate monomer and the components for making the nano-hydroxyapatite particles, adding a copolymerization catalyst to carry out copolymerization reaction, and obtaining a mixture of a copolymer matrix and nano-hydroxyapatite particles; S3, dissolving and stirring the mixture of the copolymer matrix and nano-hydroxyapatite particles, and sequentially performing precipitation, filtering, and washing steps, and vacuum drying to obtain the bioabsorbable copolymer material.

2. The preparation method according to claim 1, characterized in that: The step S2 comprises: S2.1, mixing the polylactic acid prepolymer and the vegetable oil-based cyclocarbonate monomer according to a certain proportion; S2.2, adding a mixed solution of calcium nitrate and triethyl phosphate, wherein the molar ratio of calcium to phosphorus is 1.67; S2.3, adding a copolymerization catalyst to carry out a copolymerization reaction at 160-220° C. to obtain a mixture of a copolymer matrix and nano-hydroxyapatite particles.

3. The preparation method according to claim 1, characterized in that: The copolymerization catalyst includes at least one of zinc acetylacetonate, zinc di(ethylhexanoate) and zinc oxide.

4. The preparation method according to claim 1, characterized in that: The polycondensation catalyst includes at least one of stannous octoate, stannous chloride, and dibutyltin dilaurate.

5. The preparation method according to claim 1, characterized in that: Before step S2, the method further includes: The vegetable oil is mixed with an organic solvent, and an epoxidation reagent is added to perform a dropwise reaction, and the epoxidized vegetable oil is obtained after washing; The epoxidized vegetable oil is dissolved and carbon dioxide gas is introduced, and a carbonic acid reaction catalyst is added to obtain a vegetable oil-based cyclic carbonate mixture; The vegetable oil-based cyclic carbonate mixture is subjected to reduced pressure distillation to remove impurities, thereby obtaining a vegetable oil-based cyclic carbonate monomer.

6. The preparation method according to claim 5, characterized in that: The epoxidation reagent includes at least one of a peracetic acid solution, a mixed solution of hydrogen peroxide and glacial acetic acid, and m-chloroperbenzoic acid; The reaction temperature of the dropwise addition reaction is 50-70°C, and the reaction time is 4-8h; The carbonation reaction catalyst includes at least one of triethylamine and ammonium chloride.

7. A bioabsorbable copolymer material, characterized in that: The nano-hydroxyapatite particles are prepared by the preparation method according to any one of claims 1 to 6, wherein the particle size of the nano-hydroxyapatite particles is 10 to 20 nm.

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