Biodegradable material of polylactic acid and hydroxyapatite composite and preparation method thereof

Abstract

The application relates to the technical field of biodegradable materials, in particular to a polylactic acid and hydroxyapatite composite biodegradable material and a preparation method thereof. The polylactic acid and hydroxyapatite composite biodegradable material is composed of polylactic acid, hydroxyapatite and polyethylene glycol-b-chitosan. The polyethylene glycol-b-chitosan promotes the coupling of the polylactic acid and the hydroxyapatite, forms a bonded network, and the obtained biodegradable material has good impact strength and tensile strength. Meanwhile, the polylactic acid, the hydroxyapatite and the polyethylene glycol-b-chitosan all have biocompatibility and biodegradability, and the composite biodegradable material has wide application prospects in the fields of drug delivery, tissue engineering, biosensors and the like.

Description

Technical Field

[0001] This application relates to the field of biodegradable materials technology, and more specifically, to a polylactic acid and hydroxyapatite composite biodegradable material and its preparation method. Background Technology

[0002] Polylactic acid (PLA) is a biodegradable material. Products made from PLA are easily biodegradable, and it also exhibits good biocompatibility, heat resistance, and oxygen permeability. PLA has good tensile strength and ductility, but its impact strength is relatively low.

[0003] The molecular formula of hydroxyapatite is Ca. 10 (PO4)6(OH)2. Pure hydroxyapatite powder is white and can be used for bone tissue repair. Hydroxyapatite has a hexagonal crystal system and high strength, but low tensile strength.

[0004] Some approaches combine polylactic acid (PLA) with hydroxyapatite to form biodegradable composite materials, but PLA and hydroxyapatite are not easy to combine, and the resulting materials have low impact strength and tensile strength. Summary of the Invention

[0005] Given that some methods combine polylactic acid (PLA) with hydroxyapatite to form biodegradable composite materials, but PLA and hydroxyapatite are not easy to combine, and the resulting materials have low impact strength and tensile strength, this application proposes a biodegradable material composed of PLA and hydroxyapatite and its preparation method.

[0006] In the first aspect, this application proposes a biodegradable material composed of polylactic acid and hydroxyapatite, and adopts the following technical solution.

[0007] A biodegradable material composed of polylactic acid and hydroxyapatite, wherein the biodegradable material is composed of polylactic acid, hydroxyapatite and polyethylene glycol-b-chitosan.

[0008] By employing the above technical solutions, polylactic acid (PLA) and polyethylene glycol-β-chitosan (PEG-β-chitosan) can achieve chemical bonding at the interface, as can hydroxyapatite. Through the bonding effect of PEG-β-chitosan, the coupling of PLA and hydroxyapatite is promoted, forming a bonded network. The resulting biodegradable material exhibits both good impact strength and tensile strength. Furthermore, PLA, hydroxyapatite, and PEG-β-chitosan all possess biocompatibility and biodegradability, making the resulting composite biodegradable material promising for applications in drug delivery, tissue engineering, and biosensors.

[0009] As an improvement to the polylactic acid and hydroxyapatite composite biodegradable material, the mass ratio of polylactic acid, hydroxyapatite and polyethylene glycol-b-chitosan in the raw materials for preparing the biodegradable material is 10:(2-4):(0.5-1).

[0010] By adopting the above technical solution, at this mass ratio, hydroxyapatite and polyethylene glycol-b-chitosan are uniformly dispersed in polylactic acid, and the hydroxyapatite, polyethylene glycol-b-chitosan and polylactic acid are bonded together, which enhances the impact strength and tensile strength of the composite material.

[0011] As an improvement to the biodegradable material composed of polylactic acid and hydroxyapatite, the polylactic acid has a molecular weight of 100,000 to 300,000.

[0012] By adopting the above technical solution, polylactic acid of this molecular weight has strong toughness, and when combined with hydroxyapatite and polyethylene glycol-b-chitosan, the tensile strength of the material can be further improved.

[0013] As an improvement to the biodegradable material composed of polylactic acid and hydroxyapatite, the polylactic acid is L-polylactic acid.

[0014] By adopting the above technical solution, the material composed of L-polylactic acid, hydroxyapatite and polyethylene glycol-b-chitosan has better impact resistance and tensile strength.

[0015] As an improvement to the polylactic acid-hydroxyapatite composite biodegradable material, the hydroxyapatite has an average particle size of 15-25 nm and a specific surface area of ​​45-55 m². 2 / g.

[0016] By adopting the above technical solution, hydroxyapatite has a small particle size, reaching the nanoscale, and a large specific surface area, which allows it to fully contact polylactic acid and polyethylene glycol-b-chitosan, thereby improving the probability and efficiency of composite bonding between hydroxyapatite and polylactic acid.

[0017] As an improvement to the polylactic acid-hydroxyapatite composite biodegradable material, the polyethylene glycol-b-chitosan has a molecular weight of 2000-10000.

[0018] By adopting the above technical solution, polyethylene glycol-b-chitosan of this molecular weight has a suitable degree of grafting, which can better promote the composite of polylactic acid and hydroxyapatite, resulting in a composite material with good impact strength and tensile strength.

[0019] Secondly, this application also proposes a method for preparing a biodegradable material composed of polylactic acid and hydroxyapatite, and adopts the following technical solution.

[0020] A method for preparing a biodegradable material composed of polylactic acid and hydroxyapatite, the method comprising: The polylactic acid, hydroxyapatite, and polyethylene glycol-b-chitosan were mixed evenly under conditions of -30℃ to -20℃ to obtain a mixture; the mixture was heated to 180℃ to 220℃ under continuous stirring and maintained at 180℃ to 220℃ for 3-5 hours to obtain the biodegradable material.

[0021] By adopting the above technical solution, the polylactic acid, hydroxyapatite, and polyethylene glycol-b-chitosan are in powder form at -30℃ to -20℃, allowing for thorough and uniform mixing. At a temperature of 180℃ to 220℃, the polylactic acid, hydroxyapatite, and polyethylene glycol-b-chitosan begin a composite reaction. Maintaining this temperature for 3-5 hours ensures the composite reaction proceeds fully, resulting in a high conversion rate for the biodegradable material.

[0022] As an improvement to the preparation method of the polylactic acid and hydroxyapatite composite biodegradable material, the step of heating the mixture to 180℃~220℃ and maintaining it at 180℃~220℃ for 3-5 hours is carried out in an oxygen-free environment.

[0023] By adopting the above technical solution, an anaerobic environment can prevent polylactic acid from being oxidized at temperatures of 180℃ to 220℃, thereby reducing raw material consumption and increasing yield.

[0024] In summary, the polylactic acid and hydroxyapatite composite biodegradable material and its preparation method of this application have the following beneficial effects: Polyethylene glycol-β-chitosan promotes the coupling of polylactic acid (PLA) and hydroxyapatite, forming a bonded network. The resulting biodegradable material exhibits both good impact and tensile strength. Furthermore, PLA, hydroxyapatite, and polyethylene glycol-β-chitosan all possess biocompatibility and biodegradability, making the resulting composite biodegradable material promising for applications in drug delivery, tissue engineering, and biosensors. Detailed Implementation

[0025] The following examples, comparative examples, and experimental cases illustrate the polylactic acid and hydroxyapatite composite biodegradable material of this application and its preparation method.

[0026] Information on some of the raw materials used in this embodiment is as follows.

[0027] Polylactic acid (PLLA) is a white to pale yellow powder with a molecular weight of 100,000 or 300,000.

[0028] Hydroxyapatite, a white powder with an average particle size of 20 nm and a specific surface area of ​​50 m².2 / g.

[0029] Polyethylene glycol-β-chitosan is a white powder at -20°C and a liquid at room temperature (20°C). It has an average molecular weight of 5000.

[0030] Polylactic acid (PDLA) with a molecular weight of 100,000 or 300,000.

[0031] Racemic polylactic acid (PDLLA) with a molecular weight of 100,000 or 300,000.

[0032] Example 1 Polylactic acid (PLLA), hydroxyapatite, and polyethylene glycol-β-chitosan were vacuum dried to remove moisture. The PLLA was L-PLLA with a molecular weight of 100,000. PEG-β-chitosan was used as an additive. Samples were taken in parts by weight: 10 parts of dried L-PLLA, 3 parts of dried hydroxyapatite, and 0.7 parts of dried PEG-β-chitosan. The PLLA, hydroxyapatite, and PEG-β-chitosan were placed in a high-speed mixer at -20°C and mixed thoroughly at 1500 rpm for 10–30 minutes to obtain a mixture. Nitrogen gas was used to replace the air in the high-speed mixer, creating a nitrogen-protected atmosphere. The mixture was heated to 180°C and maintained at 180°C for 4 hours under continuous stirring to obtain the biodegradable material.

[0033] Example 2 This embodiment uses the same method as in Example 1 to prepare the biodegradable material, the only difference being that the molecular weight of polylactic acid (PLLA) is 300,000.

[0034] Example 3 This embodiment uses the same method as Example 1 to prepare the biodegradable material. The only difference is that the polylactic acid in this embodiment is dextrorotatory polylactic acid (PDLA) with a molecular weight of 100,000.

[0035] Example 4 This embodiment uses the same method as Example 1 to prepare the biodegradable material. The only difference is that the polylactic acid in this embodiment is dextrorotatory polylactic acid (PDLA) with a molecular weight of 300,000.

[0036] Example 5 This embodiment uses the same method as in Example 1 to prepare the biodegradable material. The only difference is that the polylactic acid in this embodiment is racemic polylactic acid (PDLLA) with a molecular weight of 100,000.

[0037] Example 6 This embodiment uses the same method as Example 1 to prepare the biodegradable material. The only difference is that the polylactic acid in this embodiment is racemic polylactic acid (PDLLA) with a molecular weight of 300,000.

[0038] Comparative Example 1 This comparative example uses the same method as Example 1 to prepare the biodegradable material, the only difference being that polyethylene glycol and chitosan in a 1:1 mass ratio are used instead of polyethylene glycol-b-chitosan. The specific scheme of this comparative example is as follows.

[0039] Polylactic acid (PLLA), hydroxyapatite, polyethylene glycol (PEG), and chitosan were vacuum dried to remove moisture. The PLLA was L-PLLA with a molecular weight of 100,000. Samples were taken in parts by mass: 10 parts of dried PLLA, 3 parts of dried hydroxyapatite, and 0.7 parts of a 1:1 mixture of dried PEG and chitosan. The mixture was placed in a high-speed mixer at -20°C and mixed thoroughly at 1500 rpm for 10–30 minutes to obtain the final mixture. Nitrogen gas was used to replace the air in the mixer, creating a nitrogen-protected atmosphere. The mixture was heated to 200°C and maintained at 200°C for 4 hours under continuous stirring to obtain the biodegradable material.

[0040] Comparative Example 2 The biodegradable material in this comparative example was prepared using the same method as in Example 1. The only difference is that the raw materials in this comparative example include polylactic acid and hydroxyapatite, but polyethylene glycol-b-chitosan was not added.

[0041] Comparative Example 3 The biodegradable material in this comparative example was prepared using the same method as in Example 1. The only difference was that polyethylene glycol was used instead of polyethylene glycol-b-chitosan in this comparative example.

[0042] Comparative Example 4 The biodegradable material in this comparative example was prepared using the same method as in Example 1. The only difference was that the same mass of chitosan was used instead of polyethylene glycol-b-chitosan in this comparative example.

[0043] Experimental Example 1 The notched impact strength and tensile strength of the biodegradable materials in Examples 1-6 and Comparative Examples 1-4 were tested according to GB / T29284-2012. The test results are shown in Table 1.

[0044] Table 1. Notched impact strength and tensile strength test data of biodegradable materials As shown in Table 1, in Examples 1-6, under the same conditions, when polylactic acid (PLA), hydroxyapatite, and polyethylene glycol-β-chitosan were used to prepare biodegradable materials, the impact strength and tensile strength of the prepared biodegradable materials were superior when the PLA was L-PLA or racemic PLA. In Examples 1-6, for the same PLA structure, when the PLA's molecular weight was 300,000, the impact strength and tensile strength of the resulting biodegradable materials were greater than those when the PLA's molecular weight was 100,000.

[0045] As can be seen from Table 1, the biodegradable materials prepared in Examples 1-6 using polyethylene glycol-b-chitosan as an additive have significantly better impact strength and tensile strength than the biodegradable materials prepared in Comparative Example 1 using a mixture of polyethylene glycol and chitosan as an additive, Comparative Example 2 without additives, Comparative Example 3 using polyethylene glycol as an additive, and Comparative Example 4 using chitosan as an additive.

[0046] This application describes the preparation of biodegradable materials using polylactic acid (PLA), hydroxyapatite, and polyethylene glycol-β-chitosan composites. PEG-β-chitosan promotes the coupling between PLA and hydroxyapatite, forming a bonded network. The resulting biodegradable material exhibits both good impact and tensile strength. Furthermore, PLA, hydroxyapatite, and PEG-β-chitosan all possess biocompatibility and biodegradability, making the resulting composite biodegradable material promising for applications in drug delivery, tissue engineering, and biosensors.

[0047] The above are merely some embodiments of this application. The scope of protection of this application is not limited to the above embodiments. For those skilled in the art, any improvements and modifications made without departing from the inventive design of this application should also fall within the scope of protection of this application.

Claims

1. A biodegradable material composed of polylactic acid and hydroxyapatite, characterized in that, The biodegradable material is composed of polylactic acid, hydroxyapatite and polyethylene glycol-b-chitosan; In the raw materials for preparing the biodegradable material, the mass ratio of polylactic acid, hydroxyapatite, and polyethylene glycol-b-chitosan is 10:(2~4):(0.5~1). The preparation method of the biodegradable material includes: mixing polylactic acid, hydroxyapatite and polyethylene glycol-b-chitosan uniformly at -30℃ to -20℃ to obtain a mixture; heating the mixture to 180℃ to 220℃ under continuous stirring and maintaining the temperature at 180℃ to 220℃ for 3-5 hours to obtain the biodegradable material; The process of heating the mixture to 180℃~220℃ and maintaining it at 180℃~220℃ for 3-5 hours is carried out in an anaerobic environment. The molecular weight of the polylactic acid is 300,000; The polylactic acid is L-polylactic acid; The hydroxyapatite has an average particle size of 15-25 nm and a specific surface area of ​​45-55 m². 2 / g; The molecular weight of the polyethylene glycol-b-chitosan is 2000~10000.

Images