A seawater-degradable polyglycolic acid antibacterial composite material and a preparation method thereof
By adding chitosan, antioxidants, and chain extenders to polyglycolic acid, a seawater-degradable antibacterial composite material with excellent antibacterial and mechanical properties was prepared. This solved the problems of polyglycolic acid lacking antibacterial properties and declining mechanical properties, and achieved high-temperature stability and extended service life of the material.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HAINAN UNIV
- Filing Date
- 2025-04-24
- Publication Date
- 2026-06-12
AI Technical Summary
Polyglycolic acid lacks antibacterial properties, which limits its application in the medical field, and the weak interfacial interaction between chitosan and the polymer matrix leads to a decline in mechanical properties.
Using polyglycolic acid as the matrix resin and adding chitosan as an antibacterial additive, and through the combined use of antioxidants and chain extenders, high-temperature thermal degradation is inhibited and molecular weight is increased, thus preparing a seawater-degradable antibacterial composite material with excellent performance.
It significantly improves the antibacterial and mechanical properties of polyglycolic acid, extends the thermal stability and service life of the material, while maintaining good processability.
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a seawater-degradable polyglycolic acid antibacterial composite material, and particularly to a method for preparing seawater-degradable polyglycolic acid, belonging to the field of seawater-degradable plastics. Background Technology
[0002] Polyglycolic acid (PEG) is the simplest linear seawater-degradable polymer among aliphatic polyesters. Its raw material is methyl acetate, a byproduct of coal-to-ethylene glycol production, which facilitates the clean and efficient utilization of coal. PEG possesses numerous advantages, including biodegradability and seawater degradability, high biocompatibility, high mechanical properties, and high barrier properties. It can serve as a substitute for polypropylene and polyethylene terephthalate (PET), showing promising applications in high-end medical products such as food packaging, surgical sutures, drug delivery systems, and tissue scaffolds.
[0003] However, polyglycolic acid does not have antibacterial properties. In order to broaden the practical application of polyglycolic acid in the medical field, reduce bacterial contamination during use, and extend the shelf life of biodegradable materials, it is necessary to endow polyglycolic acid antibacterial composite materials with certain antibacterial effects.
[0004] Compared to commercially available antibacterial agents, chitosan, derived from the shells of crustaceans (such as shrimp and crab) and the cell walls of fungi, is non-toxic and has good biocompatibility. Furthermore, chitosan is a biodegradable material, causing no environmental pollution after use, making it an ideal antibacterial agent in the medical field. However, chitosan's low Young's modulus and its weak interfacial interactions with the polymer matrix can easily lead to a decrease in the mechanical properties of the composite material. Summary of the Invention
[0005] To broaden the application of polyglycolic acid (PGA) in mid-to-high-end industries such as medical treatment, this invention aims to provide a seawater-degradable antibacterial material and its preparation method. Due to their unique steric hindrance effect, antioxidant molecules can effectively decompose peroxides generated during the oxidation process of materials, converting peroxides into stable alcohols and other inactive products, thus preventing free radical chain reactions. In addition to normal free radical scavenging, antioxidants can also prevent the splitting of hydroperoxides (one of the initial products of auto-oxidation) to form highly reactive free radicals, such as alkoxy and hydroxyl radicals. This characteristic allows antioxidants to significantly slow down or prevent the thermal degradation reaction of PGA under high temperatures or specific conditions, thereby effectively extending the thermal stability and service life of PGA materials. The addition of antioxidants can significantly slow down or prevent the thermal degradation process of PGA by hydroperoxides, significantly reducing the amount of hydroperoxides formed by the oxidation of alkyl free radicals.
[0006] During melt blending, the multi-element epoxy groups on the chain extender readily undergo ring-opening esterification reactions with the terminal carboxyl or hydroxyl groups of the polyglycolic acid and chitosan macromolecular chains. The chain extender products increase the molecular weight and melt viscosity of polyglycolic acid, and the tensile ductility of the sample is also improved due to the reactive compatibility effect brought about by the addition of the chain extender.
[0007] Therefore, this invention uses polyglycolic acid, chitosan, antioxidants and chain extenders as raw materials to prepare a seawater-degradable polyglycolic acid antibacterial composite material with excellent performance.
[0008] To achieve the above objectives, this invention provides an antibacterial composite material based on polyglycolic acid (PEG). This invention uses PEG as the matrix resin and adds chitosan as an antibacterial additive to enhance the antibacterial properties of PEG. However, the oxidation of PEG by chitosan and PEG generates peroxides, accelerating the oxidation process and significantly reducing molecular weight and melt strength, thus limiting the processing performance and practical applications of PEG. This invention incorporates antioxidants and chain extenders, utilizing free radical scavenging and chain extension reactions to effectively inhibit the thermal degradation of PEG at high temperatures and produce higher melt strength, resulting in superior performance during processing and use. The PEG raw material comprises the following components in parts by weight: PEG 99.5-94.0 parts, chitosan 0.5-2.0 parts, antioxidant 0-2.0 parts, and chain extender 0-2.0 parts, to further enhance the performance of the seawater-degradable PEG antibacterial composite material provided by this invention.
[0009] Furthermore, in the above technical solution, the polyglycolic acid has a number average molecular weight of 20~1000kDa, a glass transition temperature of 30~50 °C, a melting point of 210~240 °C, a tensile strength of 60~100 MPa, and a melt flow rate (230 °C, 2.16 kg) of 10~300 g / 10min.
[0010] Furthermore, in the above technical solution, the particle size of the chitosan is 20~500 μm; the antioxidant is an organic phosphite antioxidant (bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite); and the chain extender is a terpolymer of styrene, methyl methacrylate, and glycidyl methacrylate.
[0011] The present invention also provides a method for preparing the above-mentioned polyglycolic acid antibacterial composite material, the process of which is as follows: after the components of the polyglycolic acid antibacterial composite material raw material are vacuum dried at 40°C for 24 hours, they are melt-blended in the above proportion using a mixing equipment to obtain the product. The melt-blending temperature is 210~230°C, and a seawater-degradable polyglycolic acid antibacterial composite material is obtained.
[0012] Furthermore, in the above-mentioned technical solution, the melt blending equipment is a twin-screw extruder or a mixer; when the melt blending is carried out in the mixing equipment, the melt blending process is as follows: first, the temperature of each zone of the mixing equipment is preheated to 210~230 ℃, and then the premixed mixture is added to the mixing equipment to obtain a seawater-degradable polyglycolic acid antibacterial composite material.
[0013] The method of this invention uses seawater-degradable polyglycolic acid as the base material and chitosan as the antibacterial agent. It employs strategies such as free radical capture reaction of antioxidants and chain extension reaction of chain extenders to compensate for the easy degradation of polyglycolic acid at high temperatures, thereby obtaining a seawater-degradable antibacterial composite material with excellent mechanical properties and processability, as well as excellent antibacterial performance.
[0014] The seawater-degradable polyglycolic acid antibacterial composite material prepared by the method of this invention has a melt flow rate of 15.94~49.20 g / 10min, a 50% decomposition temperature >360 ℃, a tensile strength >118 MPa, and an impact strength >10 kJ / m. 2 It has excellent machinability and thermodynamic properties.
[0015] The seawater-degradable polyglycolic acid antibacterial composite material prepared by the method of this invention has an antibacterial rate of >99.99% against Staphylococcus aureus and Escherichia coli, demonstrating excellent antibacterial properties. Detailed Implementation
[0017] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.
[0018] The polyglycolic acid used in the embodiments of the present invention has a number average molecular weight of 20~1000 kDa, a glass transition temperature of 30~50 °C, a melting point of 210~240 °C, a tensile strength of 60~100 MPa, and a melt flow rate (230 °C, 2.16 kg) of 10~300 g / 10min.
[0019] The chitosan used in the embodiments of this invention was purchased from Xi'an Kangnuo Chemical Co., Ltd., and its particle size was 20~500 μm.
[0020] The chain extender used in the embodiments of the present invention was purchased from BASF, Germany. Its scientific name is multi-component epoxy chain extender, which is a terpolymer of styrene, methyl methacrylate and glycidyl methacrylate, model ADR-4380. The antioxidant used in the embodiments of this invention was purchased from Dongguan Kangjin New Material Technology Co., Ltd., and its scientific name is bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, model number 9228.
[0022] The present invention will be further illustrated by specific embodiments below.
[0023] Examples 1-8, Reference Examples 1-2 Preparation method of seawater-degradable antibacterial composite material: Polyglycolic acid was vacuum dried at 40℃ (Shanghai Yiheng Scientific Instrument Co., Ltd., DZF-6051) for 24 h, and then premixed with chitosan, chain extender, and antioxidant in a certain proportion. The premixed mixture was added to a mixing equipment, and the seawater-degradable polyglycolic acid antibacterial composite material was prepared by melt blending.
[0024] Table 1 Formulation of Seawater-Degradable Polyglycolic Acid Antibacterial Composite Material
[0025] 1) Melt flow rate Melt flow rate is the weight of thermoplastic melt passing through a specific die within 10 minutes under certain temperature and pressure. The melt index is affected by a series of factors such as the average molecular weight of the sample. In the application of thermoplastics, it is necessary to control the melt flow rate of the chips within a reasonable range.
[0026] According to GB / T 3682.1-2018, the melt flow rate of the samples prepared in Reference Examples 1-2 and Examples 1-8 was tested using a melt flow rate tester (Shanghai Sierda Scientific Instruments Co., Ltd., XNR-400A). The test conditions were a temperature of 230℃ and a load of 2.16kg. Table 2 Melt Flow Rate
[0027] sample MFR (g / 10min) sample MFR (g / 10min) Reference example 1 29.88 Reference example 2 14.01 Example 1 39.59 Example 5 15.94 Example 2 41.52 Example 6 18.52 Example 3 43.99 Example 7 21.79 Example 4 49.20 Example 8 25.45 Table 2 shows that the melt flow rate of the composite material gradually increases with the increase of chitosan. Only 0.5 wt% chitosan leads to a 32.50% increase in the melt flow rate of polyglycolic acid. This is because, under the action of chitosan, polyglycolic acid decomposes into glycolide, significantly reducing its molecular weight and melt strength. After adding chain extenders and antioxidants, the melt flow rate of the polyglycolic acid antibacterial composite material decreases to 15.94 g / 10 min. Even with further increases in chitosan dosage, the increasing trend in melt flow rate is not significant with corresponding increases in antioxidants and chain extenders. This is because the reaction of chain extenders with polyglycolic acid increases molecular weight and viscosity, promoting nucleation, while the free radical scavenging reaction of antioxidants effectively inhibits the thermal degradation of polyglycolic acid.
[0028] 2) Thermal stability The thermal degradation temperatures of Reference Examples 1-2 and Examples 1-8 were tested using a simultaneous thermal analyzer (NETZSCH GmbH, Germany, STA 449 F5 Jupiter) under the following conditions: starting from room temperature of 30°C and continuously increasing the temperature to 600°C at a rate of 10°C / min, with nitrogen as the purge gas and a flow rate of 50 mL / min. The results are shown in Table 3.
[0029] Table 3 Thermal Degradation Temperature sample <![CDATA[ T -5% (℃)]]> <![CDATA[ T -50% (℃)]]> <![CDATA[ T -95% (℃)]]> <![CDATA[ T P (℃)]]> Reference example 1 333.90 371.58 389.77 376.76 Example 1 313.38 345.76 363.31 353.13 Example 2 311.26 343.68 357.86 347.30 Example 3 309.44 337.66 354.34 343.61 Example 4 309.33 336.48 351.84 339.56 Reference example 2 347.55 386.23 413.84 392.50 Example 5 348.87 383.83 407.72 388.16 Example 6 355.32 387.15 410.95 392.87 Example 7 357.10 388.49 415.32 395.21 Example 8 360.24 390.29 416.82 397.98 As shown in Table 3, the addition of antioxidants and chain extenders compensated for the decomposition of chitosan and effectively improved the thermal stability of the slices.
[0030] Tensile strength is the maximum tensile stress a material can withstand while maintaining a certain stress state; impact strength is the material's ability to resist fracture or absorb energy under high-speed impact or instantaneous load, reflecting its toughness and resistance to brittleness; elongation at break is the length of the material when it breaks minus the length of the slice before stretching, used to evaluate the toughness and ductility of plastics.
[0031] The slices prepared according to Examples 1-2 and Examples 1-8 were used to prepare dumbbell-shaped specimens of 75×50×20 mm using a micro injection molding machine (Shanghai Xinshuo Precision Instrument Co., Ltd., WZS05) at 230 °C. The mechanical properties of the specimens were measured using a universal testing machine (Jinan-Nuoshiji Experimental Instrument Co., Ltd. WDW-1). The effective tensile portion of the sample was 25 mm, and the tensile speed was 50 mm / min. The average value was taken after 5 parallel experiments, as shown in Table 4.
[0032] Table 4 Mechanical Properties sample Tensile strength (MPa) <![CDATA[Impact strength (kJ / m 2 )]]> Elongation at break (%) sample Tensile strength (MPa) <![CDATA[Impact strength (kJ / m 2 )]]> Elongation at break (%) Reference example 1 105.7 5.75 8.342 Reference example 2 116.9 6.86 10.158 Example 1 84.4 4.49 8.076 Example 5 113.3 6.72 10.111 Example 2 88.3 4.31 8.284 Example 6 115.2 7.91 11.143 Example 3 87.8 4.44 8.256 Example 7 117.7 9.18 12.641 Example 4 82.0 4.29 8.252 Example 8 118.4 10.21 14.083 As shown in Table 4, the unique steric hindrance effect of the antioxidant can effectively decompose the peroxides generated during the oxidation process of the material, converting the peroxides into stable alcohols and other inactive products, thus preventing the free radical chain reaction. Simultaneously, using a blending apparatus as a reactor, under high temperature, the epoxy functional groups in the chain extender undergo ring-opening reactions with the carboxyl and hydroxyl groups at the ends of the polyglycolic acid chain, forming new ester and hydroxyl groups, increasing the molecular weight of the polymer, thereby increasing the modulus and tensile strength.
[0033] 4) Antibacterial properties The antibacterial activity of polyglycolic acid antibacterial composite materials was tested using the film application method in Chinese national standard GB / T 31402-2015, with Escherichia coli and Staphylococcus aureus selected as representatives of Gram-negative and Gram-positive bacteria, respectively. Prepare 4 cm × 4 cm plastic films and sterilize the experimental apparatus with ultraviolet light. Prepare liquid and solid culture media according to standards, sterilize them at high temperature, inoculate the bacterial strain into the liquid culture medium, and remove them after 24 h of incubation. Then place the plate samples in the sterilized petri dishes, and drop 0.4 mL of bacterial suspension onto the surface of each sample. Then, attach the prepared sterile plastic film to the bacterial suspension. After the samples are inoculated, cover them with the film and cover the petri dishes. After incubation at 35 ℃ for 24 h, recover the bacterial suspension, dilute it, and spread it onto solid culture medium. After incubation at 35 ℃ for 48 h, count the colonies.
[0034] The inhibition rate and antibacterial activity of polyglycolic acid antibacterial composite material against Escherichia coli and Staphylococcus aureus were measured by the film application method. The results are shown in Table 5.
[0035] Table 5 Antibacterial properties sample Escherichia coli inhibition rate (%) antibacterial activity value of Escherichia coli Staphylococcus aureus inhibition rate (%) Staphylococcus aureus activity value Reference example 1 0 0 0 0 Example 1 58.31 0.33 53.23 0.38 Example 2 97.91 1.62 97.60 1.68 Example 3 99.87 2.97 99.89 2.89 Example 4 99.99 3.86 99.99 4.06 Reference example 2 0 0.02 4.50 0 Example 5 56.35 0.30 49.88 0.36 Example 6 98.40 1.67 96.81 1.59 Example 7 99.86 2.87 99.48 2.89 Example 8 100.00 3.77 99.99 4.37 Table 5 shows that for *Escherichia coli* and *Staphylococcus aureus*, the antibacterial rate of the polyglycolic acid antibacterial composite material gradually increased with the increase of chitosan concentration, reaching over 99.99% against both *Escherichia coli* and *Staphylococcus aureus*. This result indicates that the addition of chitosan significantly improves the antibacterial performance of the polyglycolic acid material. In contrast, Example 2 showed only a 4.5% inhibition rate against *Staphylococcus aureus* and no inhibitory effect against *Escherichia coli*, indicating that the chain extender and antioxidant added alone had almost no inhibitory effect on *Escherichia coli* and *Staphylococcus aureus*. With the addition of 2.0 wt% chitosan, the polyglycolic acid antibacterial composite material already achieved an inhibition rate of over 99.99%.
[0036] Polyglycolic acid (PGA) is a light beige color with relatively large particles that are roughly cylindrical in shape. The seawater-degradable PGA antibacterial composite material is brownish-yellow in color, with particles that are slightly smaller and more elongated than those of PGA.
[0037] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Equivalent modifications or variations made by those skilled in the art using the present invention should also fall within the patent protection scope of the present invention.
Claims
1. A seawater-degradable polyglycolic acid antibacterial composite material, characterized in that, The antibacterial composite material raw material includes the following components in parts by weight: 99.5-94.0 parts of polyglycolic acid, 0.5-2.0 parts of chitosan, 0-2.0 parts of antioxidant, and 0-2.0 parts of chain extender.
2. The seawater-degradable polyglycolic acid antibacterial composite material according to claim 1, characterized in that, The polyglycolic acid has a number average molecular weight of 20-1000 kDa, a glass transition temperature of 30-50 °C, a melting point of 210-240 °C, a tensile strength of 60-100 MPa, and a melt flow rate (230 °C, 2.16 kg) of 10-300 g / 10 min.
3. The chitosan according to claim 1, characterized in that, The chitosan has a particle size of 20-500 μm; the antioxidant is an organic phosphite antioxidant (bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite); and the chain extender is a terpolymer of styrene, methyl methacrylate, and glycidyl methacrylate.
4. The method for preparing the seawater-degradable polyglycolic acid antibacterial composite material according to any one of claims 1 to 3, characterized in that, After drying each component of the antibacterial composite material raw material, they are melt-blended in the above proportions using a mixing equipment to obtain the seawater-degradable polyglycolic acid antibacterial composite material.
5. The method according to claim 4, characterized in that, The mixing equipment is a twin-screw extruder or a mixer. When the melt blending is carried out in the mixing equipment, the melt blending process is as follows: each component is vacuum dried at 40 °C for 24 hours, and then premixed in a certain proportion and added to the mixing equipment. The seawater-degradable polyglycolic acid antibacterial composite material is prepared by melt blending. The blending temperature of each zone is 210~230 °C.