Plasticizer for degradable medical polymer material and preparation method thereof
By compounding degradable acylated morpholine compounds with bio-based plasticizers, the synergistic effect of amide bonds and ester bonds is constructed, which solves the problems of high hardness, poor toughness and compatibility of degradable polymer materials in the medical field, achieves the optimization of biocompatibility, controllable degradability and mechanical properties, and meets the safety requirements of medical materials.
Patent Information
- Application Number
- CN202510891469.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-10-17
AI Technical Summary
Existing biodegradable polymer materials have problems of high hardness and poor toughness in the medical field. Traditional plasticizers have problems of biotoxicity, non-degradability and poor compatibility, and cannot meet the safety and degradability requirements of medical materials.
By compounding degradable acetyl morpholine compounds with bio-based plasticizers, the synergistic effect of amide bonds and bio-based plasticizers is constructed through amidation reaction. Combined with ester bond design, two-stage degradation is achieved to form a dynamic cross-linking network, thereby improving the biocompatibility, controllable degradability and mechanical properties of the material.
It achieves improved biocompatibility, controlled degradability and optimized mechanical properties, significantly reduces plasticizer migration, meets the needs of disposable medical devices and drug sustained-release carriers, and complies with ISO 10993 standards.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of high polymer materials, and particularly relates to a plasticizer for degradable medical high polymer materials and a preparation method thereof. BACKGROUND
[0002] With the increasing demand for environmental protection, biocompatibility and degradability of disposable medical devices and implant materials, degradable polymer materials have become a research hotspot due to their excellent biodegradation performance. However, such materials generally have high hardness and poor toughness, and need to be improved in processing performance and mechanical properties by using plasticizers. Although traditional plasticizers (such as phthalate esters) can effectively improve the flexibility, they have problems such as biological toxicity, environmental persistence and non-degradability, and cannot meet the safety requirements of medical materials.
[0003] In recent years, bio-based plasticizers (such as epoxy soybean oil and citric acid esters) have attracted attention due to their low toxicity and renewable characteristics. However, single bio-based plasticizers often have defects such as poor compatibility with polymer matrix, high migration rate or uncontrollable degradation rate. For example, although epoxy soybean oil can improve the flexibility of PLA, the epoxy group is prone to ring opening during processing or use, resulting in yellowing and performance degradation of the material; citric acid ester plasticizers have good degradability, but are prone to migration and exudation, which may cause material embrittlement during long-term use. In addition, although chemical modification (such as esterification and amidation) is attempted in the prior art to improve the compatibility of the plasticizer with the matrix, most of the schemes still rely on petroleum-based raw materials (such as tall oil fatty acid), and have not achieved a breakthrough in fully bio-based degradable systems.
[0004] Therefore, it is urgent to develop a new type of degradable plasticizer which can not only reduce environmental burden through bio-based raw materials, but also achieve high compatibility, controllable degradability and long-term stability with degradable polymer matrix, so as to meet the stringent requirements in the fields of disposable medical devices and drug release carriers. SUMMARY
[0005] Therefore, the present application provides a plasticizer for degradable medical high polymer materials and a preparation method thereof.
[0006] The technical scheme of the present application is as follows: the present application provides a plasticizer for degradable medical high polymer materials, which comprises a degradable acyl morpholine compound and a bio-based plasticizing aid, the degradable acyl morpholine compound is prepared by amidation reaction of morpholine or morpholine derivatives and degradable fatty acid; the bio-based plasticizing aid is selected from at least one of epoxy soybean oil, citric acid ester and polycaprolactone polyol; wherein the degradable fatty acid is C16-C20 unsaturated fatty acid containing ester bond or hydroxyl group.
[0007] The technical scheme realizes the following technical effects by constructing degradable acyl morpholine compounds and bio-based plasticizing aids through amidation reaction:
[0008] Biocompatibility is improved: the amide bond of acyl morpholine forms hydrogen bond with the matrix such as polylactic acid, reducing the migration rate, and the low-toxicity aids such as citric acid ester and epoxy soybean oil are selected, so that the cytotoxicity is lower.
[0009] Controllable degradability: the ester bond and hydroxyl group of degradable fatty acid are designed to be preferentially broken in the in-vivo hydrolysis enzyme or body fluid environment, forming a two-stage degradation path, and realizing a degradation rate of ≥50% in 28 days.
[0010] Mechanical property optimization: the rigid structure of acyl morpholine and the flexible chain segment of bio-based aids (such as polycaprolactone polyol) synergistically act, improving the elongation at break and maintaining the tensile strength.
[0011] The above scheme balances the degradation rate, mechanical property and biological safety through molecular structure design (ester / amide bond synergistic hydrolysis), polarity matching (hydrogen bond combination of amide bond and PLA hydroxyl group) and plasticizer compounding (rigid and flexible molecular chain network), breaking through the application bottleneck of traditional plasticizers in medical scenarios.
[0012] In some embodiments, the degradable fatty acid is polylactic acid hydroxyl fatty acid, which is prepared by polylactic acid hydrolysis reaction.
[0013] In some embodiments, the preparation method of the polylactic acid hydroxyl fatty acid comprises the following steps:
[0014] (1) mixing polylactic acid and deionized water at a mass ratio of 1:3-1:5, hydrolyzing at 80-120°C for 2-6 hours to obtain an oligomeric lactic acid hydroxyl acid mixture;
[0015] (2) reacting the product of step (1) with maleic anhydride at a molar ratio of 1:0.5-1:2 at 60-90°C in dimethyl carbonate, controlling the pH of the reaction system to be 5-6, to generate polylactic acid hydroxyl fatty acid containing double bonds, and the amount of dimethyl carbonate is 1-3 times the total mass of the reactants;
[0016] (3) removing unreacted maleic anhydride by reduced pressure distillation to obtain polylactic acid hydroxyl fatty acid with an acid value of 80-150 mg KOH / g.
[0017] Through the three-step method of polylactic acid hydrolysis-double bond functionalization-purification, the comprehensive performance of the degradable plasticizer is significantly improved:
[0018] Degradation activity enhancement: hydroxy acids generated by hydrolysis contain ester bonds and carboxylic acid groups, which are preferentially hydrolyzed in a body fluid environment, achieving initial rapid degradation; the double bond introduced by maleic anhydride forms a dynamic covalent network through subsequent amidation reaction, delaying the degradation rate in the later stage, and achieving a two-stage degradation matching the tissue repair period.
[0019] Interface compatibility optimization: the low molecular weight of hydroxy acid and the steric hindrance effect of double bond promote the directional generation of linear structure (rather than crosslinking) by amidation reaction, and form a gradient compatible interface with the PLA matrix through hydrogen bonding and van der Waals force, reducing the migration rate of plasticizer.
[0020] Biological safety guarantee: the low toxicity of dimethyl carbonate and the pH control inhibit the self-polymerization side reaction of maleic anhydride, combined with the removal of acidic residues by vacuum distillation, so that the product cytotoxicity meets the ISO 10993 standard.
[0021] The above scheme realizes the precise balance of the three elements of degradation, compatibility and safety through the design of the polarity gradient of the molecular chain (polar end group of hydroxy acid + hydrophobic segment of double bond) and the control of reaction kinetics (pH adjustment of esterification / amidation rate difference).
[0022] In some embodiments, the morpholine derivative is 2-methylmorpholine or N-hydroxyethylmorpholine, and the molar ratio of morpholine compound to degradable fatty acid is 1:1-1:1.2.
[0023] By selecting 2-methylmorpholine or N-hydroxyethylmorpholine as the amidation reagent and controlling the molar ratio of morpholine compound to degradable fatty acid to be 1:1-1:1.2, the reaction efficiency and product performance are significantly improved: the methyl steric hindrance effect of 2-methylmorpholine inhibits side reactions, ensuring amidation conversion rate; the hydroxyethyl group of N-hydroxyethylmorpholine enhances the interfacial compatibility with the PLA matrix through hydrogen bonding, reducing the migration rate of plasticizer. The optimization of molar ratio (1:1-1:1.2) is based on stoichiometric balance and process tolerance design, which covers the formation of complete amide bond by carboxylic acid active site and avoids excessive reagent residue, ensuring product acid value and biological safety, providing a molecular basis for controllable degradation and long-term stability of medical materials.
[0024] In some embodiments, the bio-based plasticizing aid is a mixture of tributyl citrate and epoxy soybean oil, and the mass ratio of the two is 1:1-1:3.
[0025] The synergistic optimization of plasticizing performance is achieved by compounding tributyl citrate and epoxidized soybean oil at a mass ratio of 1:1-1:3: the flexible ester chain of TBC improves the elongation at break of PLA, while the epoxy groups of ESO inhibit the migration of plasticizers through hydrogen bonding and hydrophobic interaction, and its thermal stability delays the yellowing during processing. At this ratio, the polarity gradient of TBC and ESO matches, forming a dynamic crosslinking network that not only guarantees flexibility but also maintains material strength through the rigid epoxy structure of ESO, meeting the dual demands of mechanical properties and long-term stability for degradable medical catheters and sutures.
[0026] In some embodiments, the mass ratio of the acyl morpholine compound to the bio-based plasticizing aid is 100:(10-50).
[0027] By limiting the mass ratio of the acyl morpholine compound to the bio-based plasticizing aid to 100:10-50, the mechanical properties, degradation rate, and processability are precisely controlled: a low ratio (100:10-20) maintains high strength of the material through the rigid amide bond of acyl morpholine, suitable for high-stress scenarios such as sutures; a high ratio (100:30-50) synergistically improves flexibility and inhibits migration through the flexible chain segments of tributyl citrate and the hydrophobic interaction of epoxidized soybean oil. This ratio range forms a dynamic crosslinking network based on polarity gradient matching, ensuring process fluidity while achieving a 28-day weight loss rate of 50-70% through the synergistic degradation of double bonds / ester bonds, precisely matching the tissue repair period and meeting the differentiated needs of medical scenarios such as catheters, sutures, etc.
[0028] The second aspect of the present application also provides a preparation method of the above-mentioned plasticizer, comprising the following steps:
[0029] Step one, mix morpholine or morpholine derivatives, degradable fatty acids, catalyst, and diethylene glycol dimethyl ether, pressurize to 0.3-0.5 MPa under nitrogen protection, heat to 160-180℃, and react for 3-5 hours to obtain an acyl morpholine compound, and the addition amount of diethylene glycol dimethyl ether is 50-100% of the total mass of morpholine and fatty acids;
[0030] Step two, cool the acyl morpholine compound of step one to 60-80℃, add a bio-based plasticizing aid and a stabilizer, adjust the pH to 6-7, and stir and mix for 1-2 hours;
[0031] Step three, perform molecular distillation under a vacuum degree of ≤100 Pa and a temperature of 120-150℃ to remove unreacted monomers and low-boiling substances, obtaining a degradable plasticizer with a Gardner color degree of ≤2.
[0032] The preparation method realizes precise synthesis of high-performance degradable plasticizer through a three-step process: in step one, diethylene glycol dimethyl ether (added amount 50-100%) is used as a solvent to promote efficient amidation of morpholine derivatives and fatty acids under the conditions of 0.3-0.5 MPa pressure and 160-180 DEG C, and to inhibit solvent volatilization and side reactions; in step two, a biobased plasticizing aid and a glycidyl ester stabilizer are compounded at 60-80 DEG C and pH 6-7, and the ring opening of the epoxy group is inhibited and the interfacial compatibility is enhanced through pH control; in step three, molecular distillation is used to remove unreacted monomers and low-boiling substances, and high-purity products with a Gardner color number of less than or equal to 2 are obtained. Through the synergistic control of reaction-compounding-purification, the process takes into account reaction efficiency, thermal stability and biological safety, and provides a low-toxicity and controllable degradation plasticizing solution for medical degradable materials.
[0033] In some embodiments, the catalyst is hypophosphorous acid or p-toluenesulfonic acid, and the added amount is 0.1-1% of the total mass of the reactants; the stabilizer is a glycidyl ester compound, and the added amount is 0.5-2% of the total mass of the reactants.
[0034] By selecting hypophosphorous acid or p-toluenesulfonic acid as the catalyst and glycidyl ester compounds as the stabilizer, efficient and controllable amidation reaction and product stability are realized: the weak acidity and reducing property of hypophosphorous acid inhibit the oxidation side reaction of fatty acids, and the strong acidity of p-toluenesulfonic acid accelerates the formation of amide bonds; glycidyl ester neutralizes the residual acid through the epoxy group, inhibits the ring opening yellowing of epoxidized soybean oil and the hydrolysis of acetyl morpholine amide bonds, and its long-chain structure enhances the compatibility of the plasticizer with the matrix. This combination takes into account reaction efficiency, product color and long-term thermal stability through the dual mechanisms of acid catalysis and dynamic stabilization, and provides a reliable process basis for the industrial production of medical degradable materials.
[0035] In a third aspect, the application also provides a degradable medical polymer material, which comprises a polylactic acid or polycaprolactone matrix and the above-mentioned plasticizer, and the added amount of the plasticizer is 10-40% of the mass of the matrix.
[0036] In a fourth aspect, the application also provides an application of the above-mentioned degradable medical polymer material, which is used for producing disposable medical catheters, surgical sutures or drug release carriers.
[0037] The application has the following beneficial effects compared with the prior art:
[0038] The application realizes the breakthrough of the comprehensive performance of medical degradable materials through the innovative design of the compound system of bio-based raw materials and acyl morpholine-bio-based plasticizers: the hydrogen bond interaction and polarity gradient matching of amide bond significantly reduce the migration rate of plasticizers and improve biocompatibility; the two-stage mechanism of preferential hydrolysis of ester bond and slow release degradation of amide bond precisely controls the in vitro degradation rate of the material; the dynamic crosslinking network of the compound ratio (100:10-50) improves the elongation at break of polylactic acid, which is suitable for suture, catheter and other high stress or flexible scenes; combined with the molecular distillation process and glycidyl ester stabilizer, the processing yellowing is inhibited, and the carbon footprint of the whole bio-based system is reduced, providing a green plasticizing solution with high safety, controllable degradability and industrial feasibility for the medical field. DETAILED DESCRIPTION
[0039] The technical solutions in the embodiments of the application will be clearly and completely described below in combination with the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the application.
[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which embodiments of the application belong. If the definitions set forth in this section are contrary to or otherwise inconsistent with the definitions set forth in the patents, patent applications, published patent applications, and other publications that are herein incorporated by reference, the definitions set forth in this section prevail over the definitions that are incorporated herein by reference.
[0041] The methods used in the following examples are conventional unless otherwise stated. The materials, reagents and instruments used are conventional in the art unless otherwise stated, and are available to those skilled in the art through commercial channels.
[0042] When a range, preferably a range, or a range of upper limit preferred values and lower limit preferred values is expressed, it should be understood that all ranges formed by any pair of range upper limit or preferred value and any range lower limit or preferred value are specifically disclosed, regardless of whether the range is disclosed separately. For example, when the range "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range. In the specification and claims of this application, the range definitions can be combined and / or interchanged if not otherwise stated, and these ranges include all sub-ranges contained therein.
[0043] Example 1
[0044] Bio-based acetyl morpholine plasticizer (formulated with tributyl citrate)
[0045] Raw materials and dosages:
[0046] Polylactic acid (PLA): 1000 kg
[0047] Deionized water: 4000 kg (for hydrolysis, PLA: water = 1:4)
[0048] Maleic anhydride: dosed at a 1:1 molar ratio (reaction of hydrolysis product hydroxy acid with maleic anhydride)
[0049] N-hydroxyethyl morpholine: 1:1.1 molar ratio with hydroxy acid
[0050] Hypophosphorous acid catalyst: 0.5% of the total reaction mass (about 50 kg)
[0051] Tributyl citrate (TBC): 300 kg (acetyl morpholine: TBC = 100:30)
[0052] Glycidyl ester stabilizer: 20 kg
[0053] Preparation process:
[0054] Hydrolysis reaction:
[0055] PLA is mixed with deionized water, heated to 100°C, and stirred for 4 hours to produce an oligomeric lactic acid hydroxy acid mixture.
[0056] Double bond functionalization:
[0057] The hydrolysis product is reacted with maleic anhydride at 80°C in dimethyl carbonate at pH = 5.5 for 5 hours, and then distilled under reduced pressure (vacuum degree ≤ 100 Pa) to obtain a polylactic acid hydroxy fatty acid with an acid value of 120 mg KOH / g.
[0058] Amidation reaction:
[0059] N-hydroxyethyl morpholine, polylactic acid hydroxy fatty acid, hypophosphorous acid, and diethylene glycol dimethyl ether (solvent dosage 80%) are mixed, pressurized to 0.4 MPa under nitrogen protection, heated to 170°C, and reacted for 4 hours, then cooled to 70°C.
[0060] Formulation and purification:
[0061] TBC and stabilizer are added, the pH is adjusted to 6.5, and stirring is performed for 1.5 hours.
[0062] Molecular distillation: 130℃, vacuum degree ≤100Pa, remove low boiling point (residual ≤0.1%), get plasticizer Gardner color ≤1.8.
[0063] Example 2
[0064] High flexibility epoxy soybean oil compound system
[0065] On the basis of example 1, replace tributyl citrate with epoxy soybean oil, epoxy soybean oil (ESO): 500kg (acyl morpholine: ESO = 100:50), catalyst: p-toluene sulfonic acid catalyst: 0.8% (replace hypophosphorous acid)
[0066] Molecular distillation temperature increased to 150℃.
[0067] Example 3
[0068] High strength plasticizing system
[0069] On the basis of example 1, change the compound ratio: acyl morpholine: TBC = 100:10, catalyst: p-toluene sulfonic acid (0.8%).
[0070] Comparative example 1
[0071] Use traditional phthalate plasticizer.
[0072] Comparative example 2
[0073] Single acyl morpholine
[0074] On the basis of example 1, only acyl morpholine compound is used.
[0075] The plasticizers prepared in the above examples and comparative examples are used for the preparation of high molecular materials, and then performance test is carried out, and the results are shown in the following table:
[0076] Plasticizer purification treatment:
[0077] The plasticizers prepared in the examples and comparative examples are balanced for 24h in the environment of 25℃, humidity 50%, and the influence of environmental temperature and humidity is removed.
[0078] Then the polylactic acid particles are mixed with the plasticizer at a mass ratio of 6:4, the mixing equipment is a double screw extruder, the temperature is set to 165-175℃, and the screw rotation speed is 300rpm. The mixture is injection molded into standard test bars, and the mold temperature is 40℃, and the pressure holding time is 30s.
[0079] Mechanical property test:
[0080] The standard sample (thickness 2mm, width 5mm, gauge length 50mm) is clamped in the fixture.
[0081] Stretched to break at a rate of 50 mm / min.
[0082] The maximum load (tensile strength, MPa) and elongation at break (%) were recorded.
[0083] Degradation performance test:
[0084] The samples (10 x 10 x 1 mm 3 ) were immersed in PBS (liquid-solid ratio 10:1) and placed in a 37 °C shaker (100 rpm).
[0085] The PBS was changed every 7 days to avoid product accumulation.
[0086] Samples were taken at 0, 7, 14, 21, 28 days, washed and vacuum dried to constant weight.
[0087] Migration test:
[0088] The samples (50 x 50 x 1 mm 3 ) were immersed in 10% ethanol (liquid-solid ratio 20:1) and left at 40 °C for 48 hours.
[0089] The samples were removed and the plasticizer content in solution was determined by GC-MS (Agilent 7890B / 5977A).
[0090] Biocompatibility test:
[0091] Sample extract preparation: The plasticizer was immersed in DMEM medium (with 10% FBS) at 0.1 g / mL, 37 °C for 24 hours, filtered and sterilized.
[0092] Cell culture: L929 cells were seeded in 96-well plates at 1 x 10 4 cells / well and incubated for 24 hours.
[0093] Exposure treatment: The medium was changed to one containing different concentrations of extract (50%, 100%) and incubated for a further 48 hours.
[0094] MTT assay: 20 μL of MTT (5 mg / mL) was added to each well and incubated for 4 hours. The formazan crystals were solubilized with DMSO and the absorbance at 570 nm was measured. Cell viability was calculated.
[0095] Colorimetric test:
[0096] The liquid plasticizer was injected into a standard cuvette (light path 10 mm).
[0097] The Gardner colorimetric value (range 1-18, lower value = lighter color) was measured using a D65 light source (simulated daylight).
[0098]
[0099] Example 1 (TBC complexation): Elongation at break 340%, significantly higher than Comparative Example 2 (single acyl morpholide, 200%) and Comparative Example 1 (traditional phthalate, 180%). This is due to the dynamic crosslinking network formed by the rigid amide bond of acyl morpholide and the flexible ester chain of TBC, balancing rigidity and flexibility.
[0100] Example 2 (ESO complexation): Elongation at break 360%, reaching the highest value. The epoxy groups of epoxy soybean oil enhance interfacial compatibility through hydrogen bonding, while its hydrophobic segment inhibits molecular chain slipping, further improving flexibility.
[0101] Example 3 (high-strength system): Elongation at break 280%, tensile strength 32 MPa. By reducing the proportion of TBC (100:10), the rigid amide bond dominates the material network, suitable for high-stress scenarios such as sutures.
[0102] Comparative Example 1 (phthalate): Elongation at break only 180%, and migration rate as high as 5.5%, verifying the mechanical performance and safety defects of petroleum-based plasticizers.
[0103] The degradation rate of Examples 1-3 (55-70%) is much higher than that of Comparative Example 1 (10%), because the ester bond of PLA hydroxyl fatty acid is rapidly hydrolyzed in body fluids, forming an initial rapid degradation stage.
[0104] The degradation rate of Example 3 (55%) is lower than that of Example 1 (65%), indicating that the amide bond of high proportion of acyl morpholide needs a longer time to hydrolyze, achieving precise control of degradation rate.
[0105] The degradation rate of the ester bond of TBC is faster than that of the epoxy group of ESO, resulting in a lower degradation rate of Example 1 (65%) than that of Example 2 (70%).
[0106] The cell survival rate of Examples 1-3 is all ≥93%, far exceeding that of Comparative Example 1 (65%). The low toxicity synergy of the amide bond of acyl morpholide and the bio-based auxiliary agent (TBC / ESO) meets the ISO 10993 standard.
[0107] The migration rate of Examples 1-3 is ≤0.5%, due to the hydrogen bonding of the amide bond with the PLA matrix and the polarity gradient matching of the complex system, inhibiting the plasticizer from leaching out.
[0108] The high migration rate (5.5%) of Comparative Example 1 verifies the weak van der Waals force binding characteristics of phthalate.
[0109] The above merely provides the preferred embodiment of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A plasticizer for degradable medical polymer materials, characterized in that: The invention comprises a degradable acylated morpholine compound and a bio-based plasticizer, wherein the degradable acylated morpholine compound is prepared by amidation reaction between morpholine or a morpholine derivative and a degradable fatty acid; the bio-based plasticizer is selected from at least one of epoxy soybean oil, citrate, and polycaprolactone polyol; wherein the degradable fatty acid is a C16-C20 unsaturated fatty acid containing an ester bond or a hydroxyl group.
2. The plasticizer for degradable medical polymer materials according to claim 1, wherein The degradable fatty acid is polylactic acid hydroxy fatty acid, which is prepared by hydrolysis of polylactic acid.
3. The plasticizer for degradable medical polymer materials according to claim 2, wherein The preparation method of the polylactic acid hydroxy fatty acid comprises the following steps: (1) mixing polylactic acid and deionized water in a mass ratio of 1:3-1:5, and hydrolyzing at 80-120° C. for 2-6 hours to obtain an oligomeric lactic acid hydroxy acid mixture; (2) reacting the product of step (1) with maleic anhydride in a molar ratio of 1:0.5-1:2 in dimethyl carbonate at 60-90° C. for 3-8 hours, controlling the pH of the reaction system to 5-6, to generate polylactic acid hydroxy fatty acid containing double bonds, wherein the amount of dimethyl carbonate used is 1-3 times the total mass of the reactants; (3) removing unreacted maleic anhydride by distillation under reduced pressure to obtain polylactic acid hydroxy fatty acid having an acid value of 80-150 mg KOH / g.
4. The plasticizer for degradable medical polymer materials according to claim 1, wherein The morpholine derivative is 2-methylmorpholine or N-hydroxyethylmorpholine, and the molar ratio of the morpholine compound to the degradable fatty acid is 1:1-1:1.
2.
5. The plasticizer for degradable medical polymer materials according to claim 1, wherein The bio-based plasticizer is a mixture of tributyl citrate and epoxidized soybean oil, with a mass ratio of 1:1 to 1:
3.
6. The plasticizer for degradable medical polymer materials according to claim 1, wherein The mass ratio of the acetylmorpholine compound to the bio-based plasticizer is 100:(10-50).
7. The method for preparing the plasticizer for degradable medical polymer materials according to any one of claims 1 to 6, characterized in that: The steps include: Step 1: morpholine or a morpholine derivative, a degradable fatty acid, a catalyst and diethylene glycol dimethyl ether are mixed, pressurized to 0.3-0.5 MPa under nitrogen protection, heated to 160-180° C., and reacted for 3-5 hours to obtain an acylated morpholine compound, wherein the amount of diethylene glycol dimethyl ether added is 50-100% of the total mass of morpholine and fatty acid; Step 2: Cool the acetyl morpholine compound in step 1 to 60-80° C., add a bio-based plasticizer and a stabilizer, adjust the pH to 6-7, and stir and mix for 1-2 hours; Step 3: molecular distillation is performed at a vacuum degree of ≤100 Pa and a temperature of 120-150° C. to remove unreacted monomers and low-boiling substances to obtain a degradable plasticizer with a Gardner color of ≤2.
8. The preparation method according to claim 7, wherein The catalyst is hypophosphorous acid or p-toluenesulfonic acid, and the addition amount is 0.1-1% of the total mass of the reactants; the stabilizer is a glycidyl ester compound, and the addition amount is 0.5-2% of the total mass of the reactants.
9. A degradable medical polymer material, characterized in that: The invention comprises a polylactic acid or polycaprolactone matrix and the plasticizer according to any one of claims 1 to 6, wherein the added amount of the plasticizer is 10-40% of the mass of the matrix.
10. The use of the degradable medical polymer material according to claim 9, characterized in that: Used to produce disposable medical catheters, surgical sutures or drug sustained-release carriers.