Heat-resistant tough stereocomplex three-arm star PPO-PLA material as well as preparation method and application thereof

Abstract

The invention relates to a heat-resistant tough steric composite three-arm star PPO-PLA material as well as a preparation method and application thereof, and mainly aims to solve the problems that a PTMC-PLLA copolymer in the prior art is relatively high in cost and is not suitable for popularization in the aspect of engineering application. In order to solve the problem that the mechanical strength of the developed polylactic acid material is obviously reduced, by adopting the technical scheme that the stereocomplex three-arm star-shaped PPO-PLA material is a blend and comprises a three-arm star-shaped PPO-PLLA copolymer and a three-arm star-shaped PPO-PDLA copolymer, the problem is well solved, and the stereocomplex three-arm star-shaped PPO-PLA material can be applied to degradable plastic parts and degradable biological medical instruments.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and more particularly to a heat-resistant and tough stereocomposite three-arm star-shaped PPO-PLA material, a preparation method thereof, and applications thereof. Background Art

[0002] Poly (L-lactic acid) (PLLA) is a green and environmentally friendly plastic made from renewable plant resources and exhibits excellent biodegradability. PLLA has broad application prospects and is widely used in biomedicine, biopharmaceuticals, food packaging, automotive, and electronic devices. However, compared with traditional petroleum products, PLLA suffers from poor toughness and heat resistance, which significantly limits its application in these areas.

[0003] To address the brittleness of PLLA, researchers typically use blending and copolymerization methods to improve polylactic acid. However, using flexible aliphatic polyesters to modify polylactic acid presents the problem of poor compatibility during melt blending (Langmuir, 25 (2009), 4478; CN102757627A), and this often results in lower strength of the final material. Copolymerization modification methods can adjust the molecular structure to obtain polylactic acid-based materials with adjustable properties. A method for obtaining tough polylactic acid-based materials by ring-opening polymerization of LLA monomers using three-arm polytrimethylene carbonate (PTMC) to obtain three-arm PTMC-PLLA block copolymers has been reported. The resulting three-arm PTMC-PLLA block copolymers have an elongation at break of up to 328% and can maintain 80% of the Young's modulus of pure polylactic acid (Polymer Chemistry, 4 (2013), 1095-106). However, the high price of TMC monomers makes PTMC-PLLA copolymers expensive, making them unsuitable for widespread application in engineering. Literature also reports the use of polycondensed glycerol as an initiator to synthesize multi-arm LLA monomers for polymerization and modification (Polymer, 47 (2006), 429-434). Typically, low molecular weight (approximately 1000) materials such as glycerol or polycondensed glycerol are used for modification, resulting in a significant decrease in the mechanical strength of the resulting polylactic acid materials. Summary of the Invention

[0004] In order to solve the problems arising in the prior art, the inventors discovered through in-depth research that, by combining the copolymerization modification of flexible components, the modification of branched structures and the modification of stereocomposite structures, a stereocomposite three-arm star-shaped PPO-PLA material and its preparation method and application were proposed.

[0005] The proposed stereocomposite three-arm star-shaped PPO-PLA material significantly improves heat resistance compared to pure PLA. Its tensile strength and modulus are not significantly reduced compared to pure PLA, maintaining mechanical strength close to that of pure PLA. Furthermore, the inventors surprisingly discovered that this material also achieves a significant increase in tensile strength and modulus, as well as an unexpected improvement in toughness. The material's elongation at break can reach 75% or even over 80%, making it a highly practical PLA-modified material.

[0006] The present invention proposes a method for preparing a stereocomposite three-arm star-shaped PPO-PLA material. The method can prepare the stereocomposite three-arm star-shaped PPO-PLA material in a relatively simple manner, but is not intended to limit the material.

[0007] The application of the stereocomposite three-arm star-shaped PPO-PLA material proposed in the present invention is, for example but not limited to, application in degradable plastic parts and degradable biomedical devices.

[0008] One of the objects of the present invention is to provide a stereocomposite three-arm star-shaped PPO-PLA material, which is a blend comprising a three-arm star-shaped PPO-PLLA copolymer and a three-arm star-shaped PPO-PDLA copolymer.

[0009] In the above technical solution, preferably, in the material, with the total mass of the three-arm star-shaped PPO-PLLA copolymer structure and the three-arm star-shaped PPO-PDLA copolymer structure as 100%, the mass content of the three-arm star-shaped PPO-PLLA copolymer structure is preferably 40% to 60%, and the mass content of the three-arm star-shaped PPO-PDLA copolymer structure is preferably 40% to 60%; more preferably, the mass content of the three-arm star-shaped PPO-PLLA copolymer structure is preferably 45% to 55%, and the mass content of the three-arm star-shaped PPO-PDLA copolymer structure is preferably 45% to 55%.

[0010] In the above technical solution, preferably, the number average molecular weight of the three-arm star-shaped PPO-PLLA copolymer and the three-arm star-shaped PPO-PDLA copolymer are each independently selected to be 1.0×10 4 ~4.0×10 5 Da, the molecular weight dispersion coefficient, is each independently selected to be 1.4 to 3.0;

[0011] More preferably, the number average molecular weight of the three-arm star-shaped PPO-PLLA copolymer and the three-arm star-shaped PPO-PDLA copolymer is 9.5×10 4 ~4.0×10 5 Da, the molecular weight dispersion coefficient is 1.4 to 2.0.

[0012] In the above technical solution, in order to achieve a significant increase in tensile strength and modulus, as well as an unexpected increase in toughness, preferably, the number average molecular weight of the three-arm star-shaped PPO-PLLA copolymer is 9.5×10 4 ~3.0×10 5 Da; the number average molecular weight of the three-arm star-shaped PPO-PDLA copolymer is 1.0×10 5 ~3.5×10 5 Da;

[0013] More preferably, the number average molecular weight of the three-arm star-shaped PPO-PLLA copolymer is 9.5×10 4 ~2.0×10 5 Da,; the number average molecular weight of the three-arm star-shaped PPO-PDLA copolymer is 1.1×10 5 ~2.5×10 5 Da.

[0014] In the above technical solution, preferably, the molecular weight distribution coefficient of the three-arm star-shaped PPO-PLLA copolymer is 1.7 to 3.0, preferably 1.7 to 2.0; the molecular weight distribution coefficient of the three-arm star-shaped PPO-PDLA copolymer is 1.4 to 2.0, preferably 1.4 to 1.7;

[0015] In the above technical solution, it is further preferred that the three-arm star-shaped PPO-PLLA copolymer is prepared from a raw material comprising a L-lactide monomer and a three-arm polypropylene oxide; the three-arm star-shaped PPO-PDLA copolymer is prepared from a raw material comprising a D-lactide monomer and a three-arm polypropylene oxide.

[0016] In the above technical solution, in the three-arm star-shaped PPO-PLLA copolymer, PPO is polypropylene oxide, also known as propylene oxide polyether triol, and PLLA is left-rotational polylactic acid. The three-arm star-shaped PPO-PLLA copolymer has a non-limiting structure as shown in formula (I):

[0017]

[0018] In the above technical solution, in the three-arm star-shaped PPO-PDLA copolymer, PPO is polypropylene oxide, also known as propylene oxide polyether triol, and PDLA is dextrorotatory polylactic acid. The three-arm star-shaped PPO-PDLA copolymer has a non-limiting structure as shown in formula (II):

[0019]

[0020] A second object of the present invention is to provide a method for preparing a stereocomposite three-arm star-shaped PPO-PLA material as described in any one of the technical solutions described in the first object of the present invention, comprising the following steps:

[0021] (1) heating a L-lactide monomer, a three-arm polypropylene oxide, and a catalyst under vacuum conditions to react to obtain a three-arm star-shaped PPO-PLLA copolymer;

[0022] (2) heating the dextrorotatory lactide monomer, three-arm polypropylene oxide, and a catalyst under vacuum conditions to obtain a three-arm star-shaped PPO-PDLA copolymer;

[0023] (3) The three-arm star-shaped PPO-PLLA copolymer and the three-arm star-shaped PPO-PDLA copolymer are solution-blended, and after the solvent evaporates, the stereocomposite three-arm star-shaped PPO-PLA material is obtained.

[0024] In the above technical solution, preferably, in the step (1), based on the total molar amount of the L-lactide monomer and the three-arm polypropylene oxide as 100%, the molar content of the L-lactide monomer is 70% to 99%; the molar content of the three-arm polypropylene oxide is 1.0% to 30%; the amount of the catalyst added is 1 / 5000 to 1 / 1000 of the total mass of the L-lactide monomer and the three-arm polypropylene oxide; preferably, based on the total molar amount of the L-lactide monomer and the three-arm polypropylene oxide as 100%, the molar content of the L-lactide structural monomer is 75% to 97%; the molar content of the three-arm polypropylene oxide structural monomer is 3 to 25%; and the amount of the catalyst added is 1 / 4000 to 1 / 1500 of the total mass of the L-lactide monomer and the three-arm polypropylene oxide.

[0025] In the above technical solution, preferably, in step (2), based on the total molar amount of the dextrorotatory lactide monomer and the three-arm polypropylene oxide as 100%, the molar content of the dextrorotatory lactide monomer is 70% to 99%; the molar content of the three-arm polypropylene oxide is 1.0% to 30%; and the amount of the catalyst added is 1 / 5000 to 1 / 1000 of the total mass of the dextrorotatory lactide monomer and the three-arm polypropylene oxide. More preferably, based on the total molar amount of the dextrorotatory lactide monomer and the three-arm polypropylene oxide as 100%, the molar content of the dextrorotatory propyl ester structure monomer is 75% to 97%; the molar content of the three-arm polypropylene oxide structure monomer is 3 to 25%; and the amount of the catalyst added is 1 / 4000 to 1 / 1500 of the total mass of the dextrorotatory lactide monomer and the three-arm polypropylene oxide.

[0026] In the above technical solution, preferably, the solvent used in the solution blending is at least one of dichloromethane, chloroform, trifluoroacetic acid, and hexafluoroisopropanol; more preferably, the solvent used in the solution blending is a composite solvent of chloroform and hexafluoroisopropanol, wherein the volume ratio of chloroform and hexafluoroisopropanol is 95:5.

[0027] In the above technical solution, preferably, during the solution blending process, the mass content of the three-arm star-shaped PPO-PLLA is 40% to 60%, and the mass content of the three-arm star-shaped PPO-PDLA is 40% to 60%, and the total mass of the three-arm star-shaped PPO-PLLA and the three-arm star-shaped PPO-PDLA is 100%; more preferably, the mass content of the three-arm star-shaped PPO-PLLA is 45% to 55%, and the mass content of the three-arm star-shaped PPO-PDLA is 45% to 55%.

[0028] In the above technical solution, preferably, the L-lactide monomer or the D-lactide monomer and the three-arm polypropylene oxide are purified and dried before being used as the reaction material; more preferably, the optical purity of the L-lactide monomer or the D-lactide is 90-100% ee.

[0029] In the above technical solution, preferably, in step (1) or / and step (2):

[0030] The catalyst is selected from at least one of stannous octoate, stannous chloride, stannous chloride, stannous bromide, zinc chloride, zinc lactate, tin oxide, zinc oxide, and zirconium oxide; more preferably, at least one of stannous octoate and stannous chloride is selected as the catalyst.

[0031] Preferably, the vacuum degree under the vacuum conditions is 1Pa to 100Pa; more preferably, the vacuum degree under the vacuum conditions is 1Pa to 10Pa; further preferably, a protective atmosphere is first filled to drive out oxygen, and then vacuum is evacuated to form vacuum conditions; further preferably, the protective atmosphere is nitrogen or argon.

[0032] Preferably, the temperature of the heating reaction is 120-160°C; the heating reaction time is 12-96h, preferably 24-95h; more preferably, the temperature of the heating reaction is 140-150°C; the heating reaction time is 24-72h, preferably 48-72h.

[0033] Preferably, there is a post-treatment step after the heating reaction, and the post-treatment step includes dissolving the reaction product with a solvent, then precipitating it with a precipitant, and drying it to obtain the three-arm star-shaped PPO-PLLA copolymer and / or three-arm star-shaped PPO-PDLA copolymer.

[0034] Further preferably, the solvent is selected from at least one halogen-substituted alkane; the precipitant is selected from at least one C1-C4 alcohol; more preferably, the solvent is selected from at least one dichloromethane or chloroform; the precipitant is selected from at least one methanol or ethanol.

[0035] In the above technical solution, preferably, the method for purifying the L-lactide monomer or the D-lactide monomer is to recrystallize the L-lactide monomer or the D-lactide monomer in ethyl acetate at least three times, dry it under vacuum at 40°C for more than 72 hours, vacuum package it, and freeze it (-25°C) for storage until use.

[0036] In the above technical solution, preferably, the purification method of the three-arm polypropylene oxide is to remove water from the three-arm polypropylene oxide (PPO) by reduced pressure distillation, for example but not limited to removing water by reduced pressure distillation under stirring at 90°C until no obvious bubbles are generated, and then sealing and storing at low temperature (4°C) for future use.

[0037] The third object of the present invention is to provide a use of the stereocomposite three-arm star-shaped PPO-PLA material described in any of the technical solutions described in the first object of the present invention or the stereocomposite three-arm star-shaped PPO-PLA material prepared by the preparation method described in the second object of the present invention.

[0038] In the above technical solution, preferably, the application is preferably but not limited to application in degradable plastic parts and degradable biomedical devices.

[0039] More preferably, the degradable biomedical device is selected from at least one of wound dressings, cell culture scaffolds, and vascular stents.

[0040] In the present invention, the above conditions can be combined arbitrarily based on attempts in the art to obtain various preferred embodiments of the present invention.

[0041] The three-arm polypropylene oxide (PPO) used in the present invention is a star-shaped polyether polymer, which is used as an initiator in the reaction. Its functions are, firstly, to introduce chemical crosslinking points and, secondly, to increase the chain entanglement between molecules. On this basis, the introduced stereocomposite structure can effectively improve the melting point and heat resistance of the material, and even enhance the toughness of the material, achieving unexpected technical effects.

[0042] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and a separate point value, and the separate point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be considered as specifically disclosed in this article.

[0043] Compared with the prior art, the present invention has at least the following advantages:

[0044] The present invention introduces flexible PPO segments and a stereocomposite structure into pure PLA, which greatly improves the elongation at break and the melting point of the material while still maintaining a mechanical tensile strength close to that of polylactic acid.

[0045] The copolymer produced by the present invention has an elongation at break of nearly 70%, a melting point of nearly 230°C, and a tensile strength of approximately 65 MPa. Compared to pure L-polylactic acid (PLLA), the copolymer produced by the present invention has significantly improved toughness and heat resistance while maintaining a tensile strength similar to that of pure PLA. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is the FTIR spectrum of the stereocomposite three-arm star-shaped PPO-PLA material;

[0047] Figure 2 This is the DSC curve of the stereocomposite three-arm star-shaped PPO-PLA material;

[0048] Figure 3 This is the stress-strain curve of the stereocomposite three-arm star-shaped PPO-PLA material. DETAILED DESCRIPTION

[0049] The present invention will be described in detail below with reference to specific drawings and embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art to the present invention based on the contents of the present invention still fall within the scope of protection of the present invention.

[0050] It should also be noted that the various specific technical features described in the following specific embodiments can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0051] In addition, the various embodiments of the present invention may be arbitrarily combined as long as they do not violate the concept of the present invention. The technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the scope of protection of the present invention.

[0052] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, for example, they can be directly purchased from the market or prepared according to the preparation methods disclosed in the prior art.

[0053] The degradable stereocomposite three-arm star-shaped PPO-PLA material of the present invention is characterized by Fourier transform infrared spectroscopy (FTIR) to characterize the formation of its stereocomposite structure.

[0054] The thermal properties of the degradable stereocomposite three-arm star-shaped PPO-PLA material of the present invention were measured by differential scanning calorimetry (DSC). The DSC test conditions were: the sample was heated from room temperature to 240°C at a rate of 10°C / min.

[0055] The mechanical properties of the degradable stereocomposite three-arm star-shaped PPO-PLA material of the present invention are measured by a universal tensile testing machine.

[0056] Example 1

[0057] (1) 20 g of L-lactide monomer, 1.5 g of three-arm PPO (number average molecular weight of 7500 Da), and 0.008 g of stannous octoate catalyst were added to a polymerization tube that had been dehydrated and filled with argon. The polymerization tube containing the reaction material was filled with argon to drive out oxygen and evacuated, and this process was repeated three times. The evacuation was then continued, and the vacuum degree in the polymerization tube was controlled to be no higher than 1 Pa. The reaction material in the polymerization tube was heated and melted, shaken and mixed, and then cooled to room temperature in ice water and continued to be evacuated. The polymerization tube was then melted and sealed, and the fused polymerization tube was placed in a constant temperature blast oven at 145°C for 72 hours to obtain a three-arm star-shaped PPO-PLLA copolymer. The obtained product was purified and subjected to GPC (hexafluoroisopropanol phase) test, and its number average molecular weight was determined to be 99082 Da and its dispersion coefficient was 1.85.

[0058] (2) 20 g of right-handed lactide monomer, 1.5 g of three-arm PPO (number average molecular weight of 7500 Da), and 0.008 g of stannous octoate catalyst were added to a polymerization tube that had been dehydrated and filled with argon. The polymerization tube containing the reaction material was filled with argon to drive out oxygen and evacuated, and this was repeated three times. The evacuation was then continued, and the vacuum degree in the polymerization tube was controlled to be no higher than 1 Pa. The reaction material in the polymerization tube was heated and melted, shaken and mixed, and then cooled to room temperature in ice water and continued to be evacuated. The polymerization tube was then melted and sealed, and the fused polymerization tube was placed in a constant temperature blast oven at 145°C for 72 hours to obtain a three-arm star-shaped PPO-PDLA copolymer. The obtained product was purified and subjected to GPC (hexafluoroisopropanol phase) test, and its number average molecular weight was determined to be 117855 Da and its dispersion coefficient was 1.46.

[0059] (3) Take 1.5 g each of the three-arm star-shaped PPO-PLLA and three-arm star-shaped PPO-PDLA obtained in (1) and (2), dissolve them in a composite solution of chloroform and hexafluoroisopropanol (chloroform: hexafluoroisopropanol = 95:5 (v / v)), stir and dissolve, and pour into a mold. After the solvent evaporates, a stereocomposite three-arm star-shaped PPO-PLA material is obtained.

[0060] (4) Figure 1The FTIR spectrum of the stereocomposite three-arm PPO-PLA material is shown in Figure 1. P3-SC-PLA is the material obtained in Example 1, and P3-PLLA is the material obtained in Comparative Example 1. In the spectrum, compared with P3-PLLA, P3-SC-PLLA has a peak at 908 cm -1 A new absorption peak appears at the polylactic acid stereocomplex crystal. 1 In the helical chain structure, ν s The characteristic absorption peak of (C-C backbone) + γ (CH3) indicates the formation of stereocomplex crystals.

[0061] (5) Figure 2 The DSC spectrum of the stereocomposite three-arm PPO-PLA material. m ) is 169.8℃, and the crystallinity is 37.9%; the melting peak of P3-SC-PLA has two peaks, with peak point temperatures of 214.5℃ and 232.4℃, respectively, and the crystallinity is 32.0%. The P3-SC-PLA material has a higher melting point, indicating that it has better heat resistance.

[0062] (6) The mechanical test parameters of the stereocomposite three-arm PPO-PLA material are: tensile speed 5mm / min, dumbbell-shaped spline, length 50mm, width 4mm. Four parallel splines were tested for each sample. The average value was taken, and the tensile strength of the sample was 63.1MPa, the Young's modulus was 1845MPa, and the elongation at break was 77.0%. The stress-strain curve of the test is shown in Figure 2. Figure 3 shown.

[0063] Comparative Example 1

[0064] 20g of left-handed lactide monomer, 1.5g of three-arm PPO (number average molecular weight of 7500Da), and 0.008g of stannous octoate catalyst were added to a polymerization tube that had been freed of water adsorbed on the tube wall and filled with argon. The polymerization tube containing the reaction material was filled with argon to drive out oxygen and evacuated, and this was repeated three times. The vacuum was then continuously drawn, and the vacuum degree in the polymerization tube was controlled to be no higher than 1Pa. The reaction material in the polymerization tube was heated to melt, shaken and mixed, and then cooled to room temperature in ice water and continued to be evacuated. The polymerization tube was then fused and sealed, and the fused polymerization tube was placed in a constant temperature blast oven at 145°C for 72h to obtain a three-arm star-shaped PPO-PLLA copolymer. The obtained product was purified, and the number average molecular weight measured by GPC (hexafluoroisopropanol phase) was 99082Da, and the dispersion coefficient was 1.85. The elongation at break was measured to be 25.9%, the tensile strength was 57.2MPa, and the tensile modulus was 1607MPa. The glass transition temperature (T g ) is 55.3℃, the melting point (T m ) is 169.8℃, and the crystallinity (χc ) is 37.9%.

[0065] Comparative Example 2

[0066] (1) 37.3 g of L-lactide monomer and 0.014 g of stannous octoate catalyst were added to a polymerization tube that had been freed of water adsorbed on the tube wall and filled with argon. The polymerization tube containing the reaction material was filled with argon to drive out oxygen and evacuated, and this process was repeated three times. The evacuation was then continued, and the vacuum degree in the polymerization tube was controlled to be no higher than 1 Pa. The reaction material in the polymerization tube was heated and melted, shaken and mixed, and then cooled to room temperature in ice water and continued to be evacuated. The polymerization tube was then melted and sealed, and the fused polymerization tube was placed in a constant temperature blast oven at 145°C for 72 hours to obtain a PLLA homopolymer. The obtained product was purified and subjected to GPC (tetrahydrofuran phase) test, and its number average molecular weight was determined to be 221589 Da and its dispersion coefficient was 1.57. The elongation at break was measured to be 7.6%, the tensile strength was 60.1 MPa, and the tensile modulus was 1472 MPa. The glass transition temperature (T g ) is 61.4℃, the melting point (T m ) is 177.2℃, and the crystallinity (χ c ) is 39.2%.

[0067] As can be seen from the results of Comparative Example 2 and Comparative Example 1, the addition of the three-arm PPO segment in Comparative Example 1 improves the elongation at break of the material to a certain extent, while slightly decreasing the melting point and crystallinity. The improvement in elongation at break is limited. As can be seen from the results of Example 1 and Comparative Example 1, the stereocomposite three-arm star-shaped PPO-PLLA material obtained by blending the three-arm star-shaped PPO-PLLA with the three-arm star-shaped PPO-PDLA in Example 1 has a higher melting point, and both tensile strength and elongation at break are also improved.

[0068] Example 2

[0069] (1) 20 g of L-lactide monomer, 3.0 g of three-arm PPO (number average molecular weight of 7500 Da), and 0.016 g of stannous octoate catalyst were added to a polymerization tube that had been dehydrated and filled with argon. The polymerization tube containing the reaction material was filled with argon to drive out oxygen and evacuated, and this process was repeated three times. The evacuation was then continued, and the vacuum degree in the polymerization tube was controlled to be no higher than 1 Pa. The reaction material in the polymerization tube was heated and melted, shaken and mixed, and then cooled to room temperature in ice water and continued to be evacuated. The polymerization tube was then melted and sealed, and the melted polymerization tube was placed in a constant temperature blast oven at 145°C for 72 hours to obtain a three-arm star-shaped PPO-PLLA copolymer. The obtained product was purified and subjected to GPC (hexafluoroisopropanol phase) test, and its number average molecular weight was determined to be 52944 Da and its dispersion coefficient was 1.56.

[0070] (2) 20 g of right-handed lactide monomer, 3.0 g of three-arm PPO (number average molecular weight of 7500 Da), and 0.016 g of stannous octoate catalyst were added to a polymerization tube that had been dehydrated and filled with argon. The polymerization tube containing the reaction material was filled with argon to drive out oxygen and evacuated, and this was repeated three times. The evacuation was then continued, and the vacuum degree in the polymerization tube was controlled to be no higher than 1 Pa. The reaction material in the polymerization tube was heated and melted, shaken and mixed, and then cooled to room temperature in ice water and continued to be evacuated. The polymerization tube was then melted and sealed, and the fused polymerization tube was placed in a constant temperature blast oven at 145°C for 72 hours to obtain a three-arm star-shaped PPO-PDLA copolymer. The obtained product was purified and subjected to GPC (hexafluoroisopropanol phase) test, and its number average molecular weight was determined to be 55643 Da and its dispersion coefficient was 1.50.

[0071] (3) Take 1.5 g each of the three-arm star-shaped PPO-PLLA and three-arm star-shaped PPO-PDLA obtained in (1) and (2), dissolve them in a composite solution of chloroform and hexafluoroisopropanol (chloroform: hexafluoroisopropanol = 95:5 (v / v)), stir and dissolve, and pour into a mold. After the solvent evaporates, a stereocomposite three-arm star-shaped PPO-PLA material is obtained.

[0072] The stereocomposite three-arm star-shaped PPO-PLA material prepared by the above method has a melting point of 220.5° C., a tensile strength of 60.5 MPa, a Young's modulus of 1745 MPa, and an elongation at break of 10.7%.

[0073] Example 3

[0074] (1) 40 g of L-lactide monomer, 1.5 g of three-arm PPO (number average molecular weight of 7500 Da), and 0.008 g of stannous octoate catalyst were added to a polymerization tube that had been dehydrated and filled with argon. The polymerization tube containing the reaction material was filled with argon to drive out oxygen and evacuated, and this process was repeated three times. The evacuation was then continued, and the vacuum degree in the polymerization tube was controlled to be no higher than 1 Pa. The reaction material in the polymerization tube was heated and melted, shaken and mixed, and then cooled to room temperature in ice water and continued to be evacuated. The polymerization tube was then melted and sealed, and the fused polymerization tube was placed in a constant temperature blast oven at 145°C for 72 hours to obtain a three-arm star-shaped PPO-PLLA copolymer. The obtained product was purified and subjected to GPC (hexafluoroisopropanol phase) test, and its number average molecular weight was determined to be 189723 Da and its dispersion coefficient was 1.85.

[0075] (2) 40 g of right-handed lactide monomer, 1.5 g of three-arm PPO (number average molecular weight of 7500 Da), and 0.008 g of stannous octoate catalyst were added to a polymerization tube that had been desorbed from the tube wall and filled with argon. The polymerization tube containing the reaction material was filled with argon to drive out oxygen and evacuated, and this was repeated three times. The evacuation was then continued, and the vacuum degree in the polymerization tube was controlled to be no higher than 1 Pa. The reaction material in the polymerization tube was heated to melt, shaken and mixed, and then cooled to room temperature in ice water and continued to be evacuated. The polymerization tube was then melted and sealed, and the fused polymerization tube was placed in a constant temperature blast oven at 145°C for reaction for 72 hours to obtain a three-arm star-shaped PPO-PDLA copolymer. The obtained product was purified and subjected to GPC (hexafluoroisopropanol phase) test, and its number average molecular weight was determined to be 198845 Da and its dispersion coefficient was 1.46.

[0076] (3) Take 1.5 g each of the three-arm star-shaped PPO-PLLA and three-arm star-shaped PPO-PDLA obtained in (1) and (2), dissolve them in a composite solution of chloroform and hexafluoroisopropanol (chloroform: hexafluoroisopropanol = 95:5 (v / v)), stir and dissolve, and pour into a mold. After the solvent evaporates, a stereocomposite three-arm star-shaped PPO-PLA material is obtained.

[0077] The stereocomposite three-arm star-shaped PPO-PLA material prepared by the above method has a melting point of 223.1° C., a tensile strength of 67.7 MPa, a Young's modulus of 1815 MPa, and an elongation at break of 80.7%.

[0078] Example 4

[0079] (1) 20 g of L-lactide monomer, 1.0 g of three-arm PPO (number average molecular weight of 5000 Da), and 0.008 g of stannous octoate catalyst were added to a polymerization tube that had been dehydrated and filled with argon. The polymerization tube containing the reaction material was filled with argon to drive out oxygen and evacuated, and this process was repeated three times. The evacuation was then continued, and the vacuum degree in the polymerization tube was controlled to be no higher than 1 Pa. The reaction material in the polymerization tube was heated and melted, shaken and mixed, and then cooled to room temperature in ice water and continued to be evacuated. The polymerization tube was then melted and sealed, and the fused polymerization tube was placed in a constant temperature blast oven at 145°C for 72 hours to obtain a three-arm star-shaped PPO-PLLA copolymer. The obtained product was purified and subjected to GPC (hexafluoroisopropanol phase) test, and its number average molecular weight was determined to be 92028 Da and its dispersion coefficient was 1.67.

[0080] (2) 20 g of right-handed lactide monomer, 1.0 g of three-arm PPO (number average molecular weight of 5000 Da), and 0.008 g of stannous octoate catalyst were added to a polymerization tube that had been dehydrated and filled with argon. The polymerization tube containing the reaction material was filled with argon to drive out oxygen and evacuated, and this was repeated three times. The evacuation was then continued, and the vacuum degree in the polymerization tube was controlled to be no higher than 1 Pa. The reaction material in the polymerization tube was heated and melted, shaken and mixed, and then cooled to room temperature in ice water and continued to be evacuated. The polymerization tube was then melted and sealed, and the fused polymerization tube was placed in a constant temperature blast oven at 145°C for 72 hours to obtain a three-arm star-shaped PPO-PDLA copolymer. The obtained product was purified and subjected to GPC (hexafluoroisopropanol phase) test, and its number average molecular weight was determined to be 102695 Da and its dispersion coefficient was 1.72.

[0081] (3) Take 1.5 g each of the three-arm star-shaped PPO-PLLA and three-arm star-shaped PPO-PDLA obtained in (1) and (2), dissolve them in a composite solution of chloroform and hexafluoroisopropanol (chloroform: hexafluoroisopropanol = 95:5 (v / v)), stir and dissolve, and pour into a mold. After the solvent evaporates, a stereocomposite three-arm star-shaped PPO-PLA material is obtained.

[0082] The stereocomposite three-arm star-shaped PPO-PLA material prepared by the above method has a melting point of 222.6° C., a tensile strength of 60.7 MPa, a Young's modulus of 1615 MPa, and an elongation at break of 7.4%.

[0083] The present invention has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present invention without departing from the spirit and scope of the present invention, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A stereocomposite three-arm star-shaped PPO-PLA material, which is a blend comprising a three-arm star-shaped PPO-PLLA copolymer and a three-arm star-shaped PPO-PDLA copolymer.

2. The stereocomposite three-arm star-shaped PPO-PLA material according to claim 1, characterized in that: In the material, taking the total mass of the three-arm star-shaped PPO-PLLA copolymer structure and the three-arm star-shaped PPO-PDLA copolymer structure as 100%, the mass content of the three-arm star-shaped PPO-PLLA copolymer structure is 40% to 60%, and the mass content of the three-arm star-shaped PPO-PDLA copolymer structure is 40% to 60%. Preferably, the mass content of the three-arm star-shaped PPO-PLLA copolymer structure is 45% to 55%, and the mass content of the three-arm star-shaped PPO-PDLA copolymer structure is 45% to 55%.

3. The stereocomposite three-arm star-shaped PPO-PLA material according to claim 1, characterized in that: The number average molecular weight of the three-arm star-shaped PPO-PLLA copolymer and the three-arm star-shaped PPO-PDLA copolymer are each independently selected to be 1.0×10 4 ~4.0×10 5 Da, the molecular weight dispersion coefficient, is each independently selected to be 1.4 to 3.0; Preferably, the number average molecular weight of the three-arm star-shaped PPO-PLLA copolymer and the three-arm star-shaped PPO-PDLA copolymer is 9.5×10 4 ~4.0×10 5 Da, the molecular weight dispersion coefficient is 1.4 to 2.

0.

4. The stereocomposite three-arm star-shaped PPO-PLA material according to claim 1, characterized in that: The number average molecular weight of the three-arm star-shaped PPO-PLLA copolymer is 9.5×10 4 ~3.0×10 5 Da; the number average molecular weight of the three-arm star-shaped PPO-PDLA copolymer is 1.0×10 5 ~3.5×10 5 Da; Preferably, the number average molecular weight of the three-arm star-shaped PPO-PLLA copolymer is 9.5×10 4 ~2.0×10 5 Da,; the number average molecular weight of the three-arm star-shaped PPO-PDLA copolymer is 1.1×10 5 ~2.5×10 5 Da.

5. The stereocomposite three-arm star-shaped PPO-PLA material according to claim 4, characterized in that: The molecular weight distribution coefficient of the three-arm star-shaped PPO-PLLA copolymer is 1.7 to 3.0, preferably 1.7 to 2.0; the molecular weight distribution coefficient of the three-arm star-shaped PPO-PDLA copolymer is 1.4 to 2.0, preferably 1.4 to 1.7; Further preferably, the three-arm star-shaped PPO-PLLA copolymer is prepared from a raw material comprising a L-lactide monomer and a three-arm polypropylene oxide; the three-arm star-shaped PPO-PDLA copolymer is prepared from a raw material comprising a D-lactide monomer and a three-arm polypropylene oxide.

6. A method for preparing the stereocomposite three-arm star-shaped PPO-PLA material according to any one of claims 1 to 5, comprising the following steps: (1) heating a L-lactide monomer, a three-arm polypropylene oxide, and a catalyst under vacuum conditions to react to obtain a three-arm star-shaped PPO-PLLA copolymer; (2) heating the dextrorotatory lactide monomer, three-arm polypropylene oxide, and a catalyst under vacuum conditions to obtain a three-arm star-shaped PPO-PDLA copolymer; (3) The three-arm star-shaped PPO-PLLA copolymer and the three-arm star-shaped PPO-PDLA copolymer are solution-blended, and after the solvent evaporates, the stereocomposite three-arm star-shaped PPO-PLA material is obtained.

7. The method for preparing the stereocomplex three-arm star-shaped PPO-PLLA copolymer according to claim 6, characterized in that: In the step (1), based on the total molar amount of the L-lactide monomer and the three-arm polypropylene oxide as 100%, the molar content of the L-lactide monomer is 70% to 99%; the molar content of the three-arm polypropylene oxide is 1.0% to 30%; the amount of the catalyst added is 1 / 5000 to 1 / 1000 of the total mass of the L-lactide monomer and the three-arm polypropylene oxide; preferably, based on the total molar amount of the L-lactide monomer and the three-arm polypropylene oxide as 100%, the molar content of the L-lactide structural monomer is 75% to 97%; the molar content of the three-arm polypropylene oxide structural monomer is 3 to 25%; the amount of the catalyst added is 1 / 4000 to 1 / 1500 of the total mass of the L-lactide monomer and the three-arm polypropylene oxide; and / or: In step (2), based on the total molar amount of the D-lactide monomer and the three-arm polypropylene oxide as 100%, the molar content of the D-lactide monomer is 70% to 99%; the molar content of the three-arm polypropylene oxide is 1.0% to 30%; and the amount of the catalyst added is 1 / 5000 to 1 / 1000 of the total mass of the D-lactide monomer and the three-arm polypropylene oxide. Preferably, based on the total molar amount of the D-lactide monomer and the three-arm polypropylene oxide as 100%, the molar content of the D-lactide structure monomer is 75% to 97%; the molar content of the three-arm polypropylene oxide structure monomer is 3% to 25%; and the amount of the catalyst added is 1 / 4000 to 1 / 1500 of the total mass of the D-lactide monomer and the three-arm polypropylene oxide.

8. The method for preparing the stereocomposite three-arm star-shaped PPO-PLA material according to claim 6, characterized in that: The solvent used in the solution blending is at least one of dichloromethane, chloroform, trifluoroacetic acid, and hexafluoroisopropanol; preferably, the solvent used in the solution blending is a composite solvent of chloroform and hexafluoroisopropanol, wherein the volume ratio of chloroform to hexafluoroisopropanol is 95:5; and / or: During the solution blending process, the mass content of the three-arm star-shaped PPO-PLLA is 40% to 60%, and the mass content of the three-arm star-shaped PPO-PDLA is 40% to 60%, with the total mass of the two being 100%; preferably, the mass content of the three-arm star-shaped PPO-PLLA is 45% to 55%, and the mass content of the three-arm star-shaped PPO-PDLA is 45% to 55%.

9. The method for preparing the stereocomposite three-arm star-shaped PPO-PLA material according to any one of claims 5 to 8, characterized in that: The L-lactide monomer or D-lactide monomer, three-arm polypropylene oxide, and catalyst are purified and dried before use as reaction materials; preferably, the optical purity of the L-lactide monomer or D-lactide is 90-100% ee; and / or: In the step (1) and / or the step (2): The catalyst is selected from at least one of stannous octoate, stannous chloride, stannous chloride, stannous bromide, zinc chloride, zinc lactate, tin oxide, zinc oxide, and zirconium oxide; preferably, at least one of stannous octoate and stannous chloride is selected as the catalyst; and / or: The vacuum degree under the vacuum condition is 1Pa to 100Pa; preferably, the vacuum degree under the vacuum condition is 1Pa to 10Pa; further preferably, a protective atmosphere is first filled to drive out oxygen, and then vacuum is evacuated to form a vacuum condition; further preferably, the protective atmosphere is nitrogen or argon; and / or: The heating reaction temperature is 120-160° C.; the heating reaction time is 12-96 hours; preferably, the heating reaction temperature is 140-150° C.; the heating reaction time is 24-72 hours; and / or: Preferably, there is a post-treatment step after the heating reaction, and the post-treatment step comprises dissolving the reaction product with a solvent, then precipitating it with a precipitant, and drying it to obtain the three-arm star-shaped PPO-PLLA copolymer and / or the three-arm star-shaped PPO-PDLA copolymer; Further preferably, the solvent is selected from at least one halogen-substituted alkane; the precipitant is selected from at least one C1-C4 alcohol; more preferably, the solvent is selected from at least one dichloromethane or chloroform; the precipitant is selected from at least one methanol or ethanol.

10. A use of the stereocomposite three-arm star-shaped PPO-PLA material according to any one of claims 1 to 6 or the stereocomposite three-arm star-shaped PPO-PLA material prepared by the preparation method according to any one of claims 7 to 9, for example but not limited to use in degradable plastic parts and degradable biomedical devices; Preferably, the degradable medical device is selected from at least one of wound dressings, cell culture scaffolds, and vascular stents.

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