Degradable antibacterial plastic and preparation method thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HAINAN SHENKANG NEW MATERIAL TECHNOLOGY CO LTD
- Filing Date
- 2026-04-30
- Publication Date
- 2026-06-16
Smart Images
Figure CN122213640A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of biodegradable polyester materials technology, specifically to a biodegradable antibacterial plastic and its preparation method. Background Technology
[0002] In recent years, the demand for environmentally friendly and sustainable materials has sparked considerable interest in biodegradable polymers, which are typically derived from renewable resources. Among these, polylactic acid (PLA) and polybutylene succinate (PBS) have attracted significant attention due to their biodegradability, commercial viability, and favorable mechanical and thermal properties. However, each material has inherent limitations that restrict its individual application. While PLA possesses high strength and stiffness, its brittleness, poor heat resistance, and slow crystallization rate limit its performance in flexible materials and temperature-critical applications. Conversely, PBS exhibits excellent flexibility and thermal stability but lacks the mechanical stiffness and processing properties of PLA. Therefore, blending PLA with PBS has become a promising strategy for balancing mechanical, thermal, and degradation properties.
[0003] However, the incompatibility between PBS and PLA results in poor adhesion and weak interfacial strength between the two polymers, which hinders the synergistic effect of the blend. Furthermore, the poor antibacterial and UV resistance of PBS and PLA themselves further limits the application of their blends. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides a method for preparing biodegradable antibacterial plastics, comprising the following steps: Step 1: Modified magnolol reacts with triphenylphosphine to obtain a degradable antibacterial monomer; the degradable antibacterial monomer reacts with mercaptoethylamine to obtain an amino-functionalized degradable antibacterial monomer. Step 2: Succinic acid reacts with 1,4-butanediol to obtain hydroxyl-terminated PBS; Step 3: Modified biodegradable antibacterial monomers are combined with hydroxyl-terminated PBS via diisocyanate to obtain antibacterial modified PBS; Step 4: Mix polylactic acid resin, antibacterial modified PBS, and organic modified antibacterial composite nanomaterials, extrude, blow mold, and package to obtain biodegradable antibacterial plastic.
[0005] Preferably, in step one, the method for preparing the amino-functionalized degradable antibacterial monomer is as follows: Modified magnolol and triphenylphosphine were dissolved in acetonitrile, and the product was purified under a nitrogen atmosphere at 65-75℃ for 10-14 h to obtain a degradable antibacterial monomer; wherein the mass ratio of the modified magnolol, triphenylphosphine and acetonitrile was (7-10.5):(8.7-13.1):(80-120). The degradable antibacterial monomer was added to N,N-dimethylformamide and stirred. Under a nitrogen atmosphere, a 6.3 wt% solution of mercaptoethylamine in N,N-dimethylformamide was added dropwise. After the addition was complete, the mixture was stirred and reacted at 23-25°C for 10-14 h. The product was purified to obtain an amino-functionalized degradable antibacterial monomer. The mass ratio of the degradable antibacterial monomer, N,N-dimethylformamide, and the 6.3 wt% solution of mercaptoethylamine in N,N-dimethylformamide was (9.4-14.2):(120-150):(28.6-51.4). In the above process, modified magnolol and triphenylphosphine are covalently combined to form an ionic liquid degradable antibacterial monomer; the carbon-carbon double bond in the degradable antibacterial monomer reacts with the thiol group of mercaptoethylamine to obtain an amino-functionalized degradable antibacterial monomer.
[0006] Preferably, in step one, the method for preparing the modified magnolol is as follows: Magnolol and triethylamine were dissolved in dichloromethane and stirred at 0-5℃ for 10-20 min. Then, a 17.18 wt% dichloroacetyl chloride solution was added. After the addition was complete, the mixture was stirred at 0-5℃ for 40-60 min and then at 23-25℃ for 6-10 h. After the reaction was completed, the temperature was lowered to 0-5℃ and deionized water was added to quench the reaction. The product was purified to obtain modified magnolol. In the above process, magnolol, as a natural biomass, has excellent antibacterial and degradable properties. Due to its benzene ring structure, it also has excellent mechanical strength and UV resistance. The phenolic hydroxyl group of magnolol undergoes a substitution reaction with the chlorine of chloroacetyl chloride, introducing an acyl chloride group into magnolol.
[0007] Preferably, the mass ratio of magnolol, triethylamine, dichloromethane, a 17.18 wt% dichloroacetyl chloride solution in dichloromethane, and deionized water is (6.5-13):(4.9-9.8):(100-200):(64-128):(30-50).
[0008] Preferably, in step two, the method for preparing the hydroxyl-capped PBS is as follows: Succinic acid and 1,4-butanediol were mixed in a molar ratio of (1-2):(1.2-2.4), stirred, and esterified at 178-182℃ for 3.5-4.5 h. Then, 0.1% of tetrabutyl titanate was added, the temperature was raised to 210-230℃, and the vacuum was drawn to 36-44 Pa. The reaction was carried out for 40-80 min. After the reaction was completed, the mixture was cooled and discharged to obtain hydroxyl-terminated PBS. In the above process, succinic acid and 1,4-butanediol undergo a copolymerization reaction under the catalysis of tetrabutyl titanate to obtain hydroxyl-terminated PBS.
[0009] Preferably, in step three, the method for preparing the antibacterial modified PBS is as follows: Amino-functionalized degradable antibacterial monomer and hexamethylene diisocyanate were added to N,N-dimethylformamide and reacted under nitrogen atmosphere at 58-62℃ for 4-6 hours with stirring. The product was purified to obtain the modified degradable antibacterial monomer. The mass ratio of the amino-functionalized degradable antibacterial monomer, hexamethylene diisocyanate and N,N-dimethylformamide was (11-22):(3.4-6.8):(200-300). Hydroxyl-terminated PBS was added to chloroform, followed by the intermediate product and dibutyltin dilaurate. The mixture was stirred and reacted at 56-60°C for 5-7 hours under a nitrogen atmosphere. The product was purified to obtain antibacterial modified PBS. The mass ratio of the hydroxyl-terminated PBS, chloroform, intermediate product and dibutyltin dilaurate was (11.4-22.8):(250-350):(3.6-7.2):(0.05-0.09). In the above process, the isocyanate groups at both ends of hexamethylene diisocyanate react with the amino and hydroxyl groups of amino-functionalized degradable antibacterial monomers and PBS-terminated with hydroxyl groups, respectively, to graft the modified degradable antibacterial monomers onto PBS. This not only imparts antibacterial properties to PBS but also improves its mechanical strength and UV resistance. In addition, the hydroxyl and urethane groups introduced into the antibacterial modified PBS can form hydrogen bonds with the chitosan and polylactic acid matrix.
[0010] Preferably, in step four, the mass ratio of polylactic acid resin, antibacterial modified PBS, and organic modified antibacterial composite nanomaterial is (70-90):(10-30):(2-8).
[0011] Preferably, in step four, the extrusion temperature is 160-220℃.
[0012] Preferably, in step four, the method for preparing the organically modified antibacterial composite nanomaterial is as follows: Step S1: Mix 0.03 mol / L zinc acetate in ethanol, 0.05 mol / L copper nitrate in ethanol, 0.5 mol / L sodium hydroxide in ethanol, and titanium dioxide nanosheets in a ratio of (5-10) mL:(1-2) mL:(35-70) mL:(0.2-0.4) g, stir to form a suspension; react the suspension at 170-190℃ for 20-30 h; after the reaction is complete, centrifuge, wash, dry, and then calcine at 350-400℃ for 3-4 h to obtain antibacterial composite nanomaterials; Step S2: Mix 25wt% ammonia, deionized water, and ethanol in a mass ratio of (3.2-6.4):(50-100):(120-240), then add antibacterial composite nanomaterials, sonicate, and then add 3-(2,3-epoxypropoxy)propyltrimethoxysilane and ethanol. React at 60-70℃ for 2-3 hours with stirring, purify the product, and obtain functionalized antibacterial composite nanomaterials; wherein the mass ratio of the antibacterial composite nanomaterials to 3-(2,3-epoxypropoxy)propyltrimethoxysilane is (2.5-4.5):(0.3-0.9); Chitosan was added to N,N-dimethylformamide and stirred, then functionalized antibacterial composite nanomaterials were added, and the reaction was continued at 80-90℃ for 20-28 h. The product was purified to obtain organically modified antibacterial composite nanomaterials. The mass ratio of chitosan, N,N-dimethylformamide and functionalized antibacterial composite nanomaterials was (1.5-3.5):(150-300):(0.8-1.2). In the above process, copper-doped zinc oxide nanorods are grown in situ on the surface of titanium dioxide nanosheets as a carrier. Zinc oxide has excellent antibacterial properties, UV resistance, high strength, and hardness. Doping zinc oxide with copper introduces oxygen vacancies, promoting the generation of localized states within ZnO and increasing the number of surface active sites, thereby enhancing photoelectric properties. Even in dark environments, oxygen vacancies can generate superoxide radicals, resulting in better antibacterial properties. More importantly, the corrosion of zinc-copper particles forms zinc hydroxide, and the alkaline corrosion products react with the acid degradation products of polylactic acid (PLA) matrix through an acid-base neutralization reaction, accelerating the degradation of PLA. Furthermore, 3-(2 3-Epoxypropoxypropyltrimethoxysilane was used to modify the surface of antibacterial composite nanomaterials by introducing epoxy groups onto the surface. The epoxy groups reacted with the amino groups of chitosan, and chitosan was grafted onto the antibacterial composite nanomaterials to obtain organically modified antibacterial composite nanomaterials. The organic part on the surface of the organically modified antibacterial composite nanomaterials not only improved its antibacterial properties, hydrophilic properties, and biodegradability, but also the polar groups in chitosan could interact with the ester bonds and hydroxyl groups of antibacterial modified PBS and polylactic acid. Therefore, the organically modified antibacterial composite nanomaterials can be used as compatibilizers for polylactic acid and antibacterial modified PBS to improve their compatibility.
[0013] Preferably, the method for preparing the titanium dioxide nanosheets is as follows: Tetraisopropyl titanate was added to isopropanol to obtain a precursor solution; distilled water was added to the precursor solution, stirred, and the pH was adjusted to 1.8-2.2. Then, the solution was heated to 66-74℃ and maintained for 18-24 h to purify the product and obtain titanium hydroxide; wherein the mass ratio of tetraisopropyl titanate, isopropanol, and distilled water was (0.8-1.6):(12-24):(250-450); the titanium hydroxide was calcined at 390-410℃ for 1.5-2.5 h to obtain titanium dioxide nanosheets; In the above process, titanium dioxide nanosheets with a two-dimensional structure were prepared by sol-gel method using tetraisopropyl titanate as a precursor. Titanium dioxide, as a commonly used inorganic filler, has significant antibacterial and anti-ultraviolet properties and can effectively improve the mechanical properties of organic polymer matrices.
[0014] The biodegradable antibacterial plastic is prepared using the aforementioned method.
[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The biodegradable antibacterial plastic of the present invention combines the advantages of polylactic acid (PLA) and polybutylene succinate (PBS) by blending them together. It is a material with good mechanical properties, thermal stability and degradation performance, and has a wide range of applications. In particular, it can be used in packaging materials. 2. This invention modifies PBS by grafting modified biodegradable antibacterial monomers onto PBS to obtain antibacterial modified PBS. This not only imparts antibacterial properties to the PBS material but also improves its mechanical strength and UV resistance. Furthermore, the hydroxyl and urethane groups introduced into the antibacterial modified PBS can form hydrogen bonds with chitosan and polylactic acid matrices, improving its compatibility with the polylactic acid matrix and increasing the crosslinking density of the system. This further enhances the mechanical properties, antibacterial properties, and UV resistance of the biodegradable antibacterial plastic. 3. The biodegradable antibacterial plastic of the present invention also includes organically modified antibacterial composite nanomaterials. The organically modified antibacterial composite nanomaterials can not only serve as functional fillers to effectively improve the overall performance of biodegradable antibacterial plastics, but also serve as compatibilizers to improve the compatibility of polylactic acid with PBS. Attached Figure Description
[0016] Figure 1 This is a comparison chart of the Staphylococcus aureus inhibition rate test of the biodegradable antibacterial plastics prepared in Examples 2-4 and Comparative Examples 4-7 of the present invention; Figure 2 This is a comparison chart of the tensile strength tests of the biodegradable antibacterial plastics prepared in Examples 2-4 and Comparative Examples 4-7 of the present invention; Figure 3This is a comparison chart showing the retention rate of tensile strength after UV aging of the biodegradable antibacterial plastics prepared in Examples 2-4 and Comparative Examples 4-7 of the present invention. Detailed Implementation
[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0018] Example 1 This embodiment discloses a method for preparing organically modified antibacterial composite nanomaterials, including the following steps: Step S1: Add 1.2g tetraisopropyl titanate to 18g isopropanol to obtain a precursor solution; add 350g distilled water to the precursor solution, adjust the pH to 2 with nitric acid under stirring at 650r / min, then heat to 70℃ and maintain for 21h, centrifuge, wash the obtained solid product with ethanol, and vacuum dry at 70℃ for 12h to obtain titanium hydroxide; calcine the titanium hydroxide at 400℃ for 2h to obtain titanium dioxide nanosheets; 7.5 mL of 0.03 mol / L zinc acetate ethanol solution, 1.5 mL of 0.05 mol / L copper nitrate ethanol solution, 52.5 mL of 0.5 mol / L sodium hydroxide ethanol solution, and 0.3 g of titanium dioxide nanosheets were mixed and stirred for 30 min to form a suspension. The suspension was reacted at 180 °C for 24 h. After the reaction was completed, the mixture was centrifuged, and the resulting solid product was washed with distilled water until the pH of the washing solution reached 7. The product was then vacuum dried at 70 °C for 15 h and finally calcined at 375 °C for 3.5 h to obtain the antibacterial composite nanomaterial. Step S2: Mix 4.8g of 25wt% ammonia, 75g of deionized water, and 180g of ethanol, then add 3.5g of antibacterial composite nanomaterials and sonicate for 1.5h. Then add 0.6g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and 60g of ethanol. React at 65℃ for 2.5h with stirring. After the reaction is complete, centrifuge and wash the obtained solid product with distilled water until the pH of the washing solution is 7. Then vacuum dry at 70℃ for 15h to obtain functionalized antibacterial composite nanomaterials. 2.5g of chitosan (80% degree of deacetylation) was added to 225g of N,N-dimethylformamide and stirred. Then, 1g of functionalized antibacterial composite nanomaterial was added, and the mixture was stirred and reacted at 85℃ for 24h. After the reaction was completed, the mixture was centrifuged, and the resulting solid product was washed with ethanol, deionized water and acetone and dried at 30℃ for 15h to obtain organically modified antibacterial composite nanomaterial.
[0019] Example 2 This embodiment discloses a method for preparing a biodegradable antibacterial plastic, including the following steps: Step 1: Dissolve 6.5g magnolol and 4.9g triethylamine in 100g dichloromethane and stir at 0℃ for 20min. Then, over 30min, add 64g of a 17.18wt% dichloroacetyl chloride solution in dichloromethane dropwise. After the addition is complete, stir the reaction at 0℃ for 60min, then at 23℃ for 10h. After the reaction is complete, lower the temperature to 0℃ and add 30g of deionized water to quench the reaction. Extract the organic phase twice with dichloromethane, then add anhydrous magnesium sulfate for dehydration and filter. The crude product is then purified by column chromatography (ethyl acetate: petroleum ether = 1:4) to obtain modified magnolol. 7g of modified magnolol and 8.7g of triphenylphosphine were dissolved in 80g of acetonitrile. The reaction was carried out at 65℃ for 14h under a nitrogen atmosphere. After the reaction was completed, the reaction mixture was cooled to 23℃ and the solvent was removed by rotary evaporation. The crude product was then purified by column chromatography (ethyl acetate:methanol = 10:1) to obtain a biodegradable antibacterial monomer. 9.4 g of the biodegradable antibacterial monomer was added to 120 g of N,N-dimethylformamide and stirred for 20 min. Under a nitrogen atmosphere, 28.6 g of a 6.3 wt% N,N-dimethylformamide solution of mercaptoethylamine was added dropwise at a rate of 1 mL / min. After the addition was complete, the mixture was stirred and reacted at 23 °C for 10 h. The solvent and excess mercaptoethylamine were removed by rotary evaporation to obtain the amino-functionalized biodegradable antibacterial monomer. Step 2: Succinic acid and 1,4-butanediol were mixed at a molar ratio of 1:1.2, stirred, and esterified at 178°C for 4.5 h. Then, 0.1% of the total reactant mass of tetrabutyl titanate catalyst was added, the temperature was raised to 210°C, and a vacuum of 36 Pa was applied. The reaction was carried out for 80 min. After the reaction was completed, the mixture was cooled and discharged to obtain hydroxyl-terminated PBS. Step 3: Add 11g of amino-functionalized degradable antibacterial monomer and 3.4g of hexamethylene diisocyanate to 200g of N,N-dimethylformamide. Stir and react at 58°C for 6 hours under a nitrogen atmosphere. After the reaction is completed, remove the solvent by rotary evaporation to obtain the modified degradable antibacterial monomer. 11.4 g of hydroxyl-terminated PBS was added to 250 g of chloroform, followed by 3.6 g of intermediate product and 0.05 g of dibutyltin dilaurate. The mixture was stirred at 56 °C for 7 h under a nitrogen atmosphere. After the reaction was completed, the solvent was removed by rotary evaporation to obtain antibacterial modified PBS. Step 4: Mix polylactic acid resin, antibacterial modified PBS, and organic modified antibacterial composite nanomaterials in a mass ratio of 90:10:2, extrude at 160°C, blow mold, and package to obtain biodegradable antibacterial plastic.
[0020] Example 3 This embodiment discloses a method for preparing a biodegradable antibacterial plastic, including the following steps: Step 1: Dissolve 13g magnolol and 9.8g triethylamine in 200g dichloromethane and stir at 5℃ for 10min. Then, over 60min, add 128g of a 17.18wt% dichloroacetyl chloride solution in dichloromethane dropwise. After the addition is complete, stir the reaction at 5℃ for 40min, then at 25℃ for 6h. After the reaction is complete, lower the temperature to 5℃ and add 30g of deionized water to quench the reaction. Extract the organic phase four times with dichloromethane, then add anhydrous magnesium sulfate for dehydration and filter. The crude product is then purified by column chromatography (ethyl acetate: petroleum ether = 1:4) to obtain modified magnolol. 10.5 g of modified magnolol and 13.1 g of triphenylphosphine were dissolved in 120 g of acetonitrile. The reaction was carried out at 75 °C for 10 h under a nitrogen atmosphere. After the reaction was completed, the reaction mixture was cooled to 25 °C and the solvent was removed by rotary evaporation. The crude product was then purified by column chromatography (ethyl acetate:methanol = 10:1) to obtain a biodegradable antibacterial monomer. 14.2 g of the biodegradable antibacterial monomer was added to 150 g of N,N-dimethylformamide and stirred for 40 min. Under a nitrogen atmosphere, 51.4 g of a 6.3 wt% N,N-dimethylformamide solution of mercaptoethylamine was added dropwise at a rate of 2 mL / min. After the addition was complete, the mixture was stirred and reacted at 23 °C for 14 h. The solvent and excess mercaptoethylamine were removed by rotary evaporation to obtain the amino-functionalized biodegradable antibacterial monomer. Step 2: Succinic acid and 1,4-butanediol were mixed in a molar ratio of 2:2.4, stirred, and esterified at 182°C for 3.5 h. Then, 0.1% of the total reactant mass of tetrabutyl titanate catalyst was added, the temperature was raised to 230°C, and a vacuum of 44 Pa was applied. The reaction was carried out for 400 min. After the reaction was completed, the mixture was cooled and discharged to obtain hydroxyl-terminated PBS. Step 3: Add 22g of amino-functionalized degradable antibacterial monomer and 6.8g of hexamethylene diisocyanate to 300g of N,N-dimethylformamide. Stir and react at 62°C for 4h under a nitrogen atmosphere. After the reaction is complete, remove the solvent by rotary evaporation to obtain the modified degradable antibacterial monomer. 22.8g of hydroxyl-terminated PBS was added to 350g of chloroform, followed by 7.2g of intermediate product and 0.09g of dibutyltin dilaurate. The mixture was stirred at -60℃ for 5h under a nitrogen atmosphere. After the reaction was completed, the solvent was removed by rotary evaporation to obtain antibacterial modified PBS. Step 4: Mix polylactic acid resin, antibacterial modified PBS, and organic modified antibacterial composite nanomaterials in a mass ratio of 70:30:8, extrude at 220℃, blow mold, and package to obtain biodegradable antibacterial plastic.
[0021] Example 4 This embodiment discloses a method for preparing a biodegradable antibacterial plastic, including the following steps: Step 1: Dissolve 9.8g magnolol and 7.4g triethylamine in 150g dichloromethane and stir at 3℃ for 15min. Then, over 45min, add 96g of a 17.18wt% dichloroacetyl chloride solution in dichloromethane. After the addition is complete, stir the reaction at 3℃ for 50min, then at 24℃ for 8h. After the reaction is complete, lower the temperature to 3℃ and add 40g of deionized water to quench the reaction. Extract the organic phase three times with dichloromethane, then add anhydrous magnesium sulfate for dehydration and filter. The crude product is then purified by column chromatography (ethyl acetate: petroleum ether = 1:4) to obtain modified magnolol. 8.8 g of modified magnolol and 10.9 g of triphenylphosphine were dissolved in 100 g of acetonitrile. The reaction was carried out at 70 °C for 12 h under a nitrogen atmosphere. After the reaction was completed, the reaction mixture was cooled to 24 °C and the solvent was removed by rotary evaporation. The crude product was then purified by column chromatography (ethyl acetate:methanol = 10:1) to obtain a biodegradable antibacterial monomer. 11.8 g of the biodegradable antibacterial monomer was added to 135 g of N,N-dimethylformamide and stirred for 30 min. Under a nitrogen atmosphere, 40 g of 6.3 wt% mercaptoethylamine N,N-dimethylformamide solution was added dropwise at a rate of 1.5 mL / min. After the addition was complete, the mixture was stirred and reacted at 24 °C for 12 h. The solvent and excess mercaptoethylamine were removed by rotary evaporation to obtain the amino-functionalized biodegradable antibacterial monomer. Step 2: Succinic acid and 1,4-butanediol were mixed at a molar ratio of 1.5:1.8, stirred, and esterified at 180°C for 4 hours. Then, 0.1% of the total reactant mass of tetrabutyl titanate catalyst was added, the temperature was raised to 220°C, and a vacuum of 40 Pa was applied. The reaction was carried out for 60 minutes. After the reaction was completed, the mixture was cooled and discharged to obtain hydroxyl-terminated PBS. Step 3: Add 16.5g of amino-functionalized degradable antibacterial monomer and 5.1g of hexamethylene diisocyanate to 250g of N,N-dimethylformamide. Stir and react for 5h at 60℃ under a nitrogen atmosphere. After the reaction is completed, remove the solvent by rotary evaporation to obtain the modified degradable antibacterial monomer. 17.1g of hydroxyl-terminated PBS was added to 300g of chloroform, followed by 5.4g of intermediate product and 0.07g of dibutyltin dilaurate. The mixture was stirred at 58°C for 6 hours under a nitrogen atmosphere. After the reaction was completed, the solvent was removed by rotary evaporation to obtain antibacterial modified PBS. Step 4: Mix polylactic acid resin, antibacterial modified PBS, and organic modified antibacterial composite nanomaterials in a mass ratio of 80:20:5, extrude at 190°C, blow mold, and package to obtain biodegradable antibacterial plastic.
[0022] The organically modified antibacterial composite nanomaterials in Examples 2-4 above are the organically modified antibacterial composite nanomaterials prepared in Example 1.
[0023] Comparative Example 1 This comparative example discloses a method for preparing organically modified antibacterial composite nanomaterials, including the following steps: Step S1: Add 1.2g tetraisopropyl titanate to 18g isopropanol to obtain a precursor solution; add 350g distilled water to the precursor solution, adjust the pH to 2 with nitric acid under stirring at 650r / min, then heat to 70℃ and maintain for 21h, centrifuge, wash the obtained solid product with ethanol, and vacuum dry at 70℃ for 12h to obtain titanium hydroxide; calcine the titanium hydroxide at 400℃ for 2h to obtain titanium dioxide nanosheets; 7.5 mL of 0.03 mol / L zinc acetate ethanol solution, 52.5 mL of 0.5 mol / L sodium hydroxide ethanol solution, and 0.3 g of titanium dioxide nanosheets were mixed and stirred for 30 min to form a suspension. The suspension was reacted at 180 °C for 24 h. After the reaction was completed, the mixture was centrifuged, and the resulting solid product was washed with distilled water until the pH of the washing solution was 7. The product was then vacuum dried at 70 °C for 15 h and finally calcined at 375 °C for 3.5 h to obtain the antibacterial composite nanomaterial. Step S2: Mix 4.8g of 25wt% ammonia, 75g of deionized water, and 180g of ethanol, then add 3.5g of antibacterial composite nanomaterials and sonicate for 1.5h. Then add 0.6g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and 60g of ethanol. React at 65℃ for 2.5h with stirring. After the reaction is complete, centrifuge and wash the obtained solid product with distilled water until the pH of the washing solution is 7. Then vacuum dry at 70℃ for 15h to obtain functionalized antibacterial composite nanomaterials. 2.5g of chitosan (80% degree of deacetylation) was added to 225g of N,N-dimethylformamide and stirred. Then, 1g of functionalized antibacterial composite nanomaterial was added, and the mixture was stirred and reacted at 85℃ for 24h. After the reaction was completed, the mixture was centrifuged, and the resulting solid product was washed with ethanol, deionized water and acetone and dried at 30℃ for 15h to obtain organically modified antibacterial composite nanomaterial.
[0024] Comparative Example 2 This comparative example discloses a method for preparing organically modified antibacterial titanium dioxide nanosheets, comprising the following steps: Step S1: Add 1.2g tetraisopropyl titanate to 18g isopropanol to obtain a precursor solution; add 350g distilled water to the precursor solution, adjust the pH to 2 with nitric acid under stirring at 650r / min, then heat to 70℃ and maintain for 21h, centrifuge, wash the obtained solid product with ethanol, and vacuum dry at 70℃ for 12h to obtain titanium hydroxide; calcine the titanium hydroxide at 400℃ for 2h to obtain titanium dioxide nanosheets; Step S2: Mix 4.8g of 25wt% ammonia, 75g of deionized water, and 180g of ethanol, then add 3.5g of titanium dioxide nanosheets and sonicate for 1.5h. Then add 0.6g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and 60g of ethanol. React at 65℃ for 2.5h with stirring. After the reaction is complete, centrifuge and wash the obtained solid product with distilled water until the pH of the washing solution is 7. Then vacuum dry at 70℃ for 15h to obtain functionalized titanium dioxide nanosheets. 2.5 g of chitosan (80% degree of deacetylation) was added to 225 g of N,N-dimethylformamide and stirred. Then, 1 g of functionalized titanium dioxide nanosheets were added, and the mixture was stirred and reacted at 85 °C for 24 h. After the reaction was completed, the mixture was centrifuged, and the resulting solid product was washed with ethanol, deionized water and acetone and dried at 30 °C for 15 h to obtain organically modified antibacterial titanium dioxide nanosheets.
[0025] Comparative Example 3 This comparative example discloses a method for preparing organically modified antibacterial composite nanomaterials, including the following steps: Step S1: Add 1.2g tetraisopropyl titanate to 18g isopropanol to obtain a precursor solution; add 350g distilled water to the precursor solution, adjust the pH to 2 with nitric acid under stirring at 650r / min, then heat to 70℃ and maintain for 21h, centrifuge, wash the obtained solid product with ethanol, and vacuum dry at 70℃ for 12h to obtain titanium hydroxide; calcine the titanium hydroxide at 400℃ for 2h to obtain titanium dioxide nanosheets; 7.5 mL of 0.03 mol / L zinc acetate ethanol solution, 52.5 mL of 0.5 mol / L sodium hydroxide ethanol solution, and 0.3 g of titanium dioxide nanosheets were mixed and stirred for 30 min to form a suspension. The suspension was reacted at 180 °C for 24 h. After the reaction was completed, the mixture was centrifuged, and the resulting solid product was washed with distilled water until the pH of the washing solution was 7. The product was then vacuum dried at 70 °C for 15 h and finally calcined at 375 °C for 3.5 h to obtain the antibacterial composite nanomaterial. Step S2: Mix 4.8g of 25wt% ammonia, 75g of deionized water, and 180g of ethanol, then add 3.5g of antibacterial composite nanomaterials and sonicate for 1.5h. Then add 0.6g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and 60g of ethanol. React at 65℃ for 2.5h with stirring. After the reaction is complete, centrifuge and wash the obtained solid product with distilled water until the pH of the washing solution is 7. Then vacuum dry at 70℃ for 15h to obtain functionalized antibacterial composite nanomaterials, i.e., organic modified antibacterial composite nanomaterials.
[0026] Comparative Example 4 Compared with Example 4, Comparative Example 4 used the organic modified antibacterial composite nanomaterial prepared in Comparative Example 1 instead of the organic modified antibacterial composite nanomaterial prepared in Example 1 in the process of preparing biodegradable antibacterial plastic, while keeping other conditions unchanged.
[0027] Comparative Example 5 Compared with Example 4, Comparative Example 5 used organically modified antibacterial titanium dioxide nanosheets prepared in Comparative Example 2 instead of the organically modified antibacterial composite nanomaterials prepared in Example 1 in the process of preparing biodegradable antibacterial plastics, while keeping other conditions unchanged.
[0028] Comparative Example 6 Compared with Example 4, Comparative Example 6 used the organic modified antibacterial composite nanomaterial prepared in Comparative Example 3 instead of the organic modified antibacterial composite nanomaterial prepared in Example 1 in the process of preparing biodegradable antibacterial plastic, while keeping other conditions unchanged.
[0029] Comparative Example 7 Compared with Example 4, Comparative Example 6 used hydroxyl-terminated PBS instead of antibacterial modified PBS in the preparation of biodegradable antibacterial plastics, while other conditions remained unchanged.
[0030] Experimental Example The performance of the biodegradable antibacterial plastics prepared in Examples 2-4 and Comparative Examples 4-7 was tested: Test 1: Antibacterial Performance Test: Take samples from each group and test them according to the following method: Take 5g of sample and ultrasonically wash with 10mL of deionized water at room temperature, then centrifuge and dry to obtain the washed powder. Select Staphylococcus aureus as the experimental bacteria and culture it in LB broth medium at a concentration of 10. 6 Colony forming units (CFU) / mL: Add 2 mL of bacterial suspension to each well of a 12-well plate, then add 0.2 g of the above sample and set up a blank group. Incubate at 37℃ for 24 hours and calculate the inhibition rate (%) by the drop plate method. The calculation formula is (AB) / A×100, where A is the average number of colonies in the blank group and B is the average number of colonies in the experimental group. Test 2, Mechanical property test: The composite material was tested using a universal tensile testing machine at a tensile speed of 10 mm / min. The sample length was 100 mm and the width was 10 mm. Test 3, UV resistance: The samples were subjected to UV aging at room temperature for 48 hours using a UV lamp with a wavelength of 300-360nm. The samples were 10cm away from the UV lamp source. Then, the tensile strength of each sample was tested according to the method in Test 2, and the tensile strength retention rate was calculated (tensile strength retention rate = tensile strength after UV aging / tensile strength before UV aging × 100%). The test results are shown in Table 1: Table 1 ; As can be seen from the test results in Table 1, the biodegradable antibacterial plastics prepared in Examples 2-4 of this invention not only have excellent antibacterial properties, but also excellent mechanical strength and UV resistance. As can be seen from the comparison between Comparative Examples 4-5 and Example 4, using titanium dioxide nanosheets as a carrier, copper-doped zinc oxide nanorods are grown in situ on their surface. Zinc oxide has excellent antibacterial properties, UV resistance, high strength and hardness. After copper doping zinc oxide, oxygen vacancies are introduced, which promotes the generation of localized states inside ZnO and increases the number of surface active sites, thereby enhancing photoelectric properties. Even in dark environments, oxygen vacancies can generate superoxide radicals, thus having better antibacterial properties. Therefore, the presence of copper-doped nano-zinc oxide in organic modified antibacterial composite nanomaterials has a positive impact on improving the overall performance of biodegradable antibacterial plastics. As can be seen from the comparison between Comparative Example 6 and Example 4, grafting chitosan onto antibacterial composite nanomaterials yields organically modified antibacterial composite nanomaterials. The organic portion on the surface of the organically modified antibacterial composite nanomaterials not only improves their antibacterial properties, hydrophilic properties, and biodegradability, but also allows the polar groups in chitosan to interact with the ester bonds and hydroxyl groups of antibacterial modified PBS and polylactic acid. Therefore, the organically modified antibacterial composite nanomaterials can serve as a compatibilizer for polylactic acid and antibacterial modified PBS, improving their compatibility and thus enhancing the overall performance of biodegradable antibacterial plastics. As can be seen from the comparison between Comparative Example 7 and Example 4, grafting modified biodegradable antibacterial monomers onto PBS not only imparts antibacterial properties to PBS, but also improves its mechanical strength and UV resistance. In addition, the hydroxyl, urethane and other groups introduced into the antibacterial modified PBS can form hydrogen bonds with the chitosan and polylactic acid matrix, thereby giving the biodegradable antibacterial plastic better properties.
[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a biodegradable antibacterial plastic, characterized in that, Includes the following steps: Step 1: Modified magnolol reacts with triphenylphosphine to obtain a degradable antibacterial monomer; the degradable antibacterial monomer reacts with mercaptoethylamine to obtain an amino-functionalized degradable antibacterial monomer. Step 2: Succinic acid reacts with 1,4-butanediol to obtain hydroxyl-terminated PBS; Step 3: Modified biodegradable antibacterial monomers are combined with hydroxyl-terminated PBS via diisocyanate to obtain antibacterial modified PBS; Step 4: Mix polylactic acid resin, antibacterial modified PBS, and organic modified antibacterial composite nanomaterials, extrude, blow mold, and package to obtain biodegradable antibacterial plastic.
2. The method for preparing the biodegradable antibacterial plastic according to claim 1, characterized in that, In step one, the preparation method of the amino-functionalized degradable antibacterial monomer is as follows: Modified magnolol and triphenylphosphine were dissolved in acetonitrile, and the product was purified under a nitrogen atmosphere at 65-75℃ for 10-14 h to obtain a degradable antibacterial monomer; wherein the mass ratio of the modified magnolol, triphenylphosphine and acetonitrile was (7-10.5):(8.7-13.1):(80-120). The degradable antibacterial monomer was added to N,N-dimethylformamide and stirred. Under a nitrogen atmosphere, a 6.3 wt% solution of mercaptoethylamine in N,N-dimethylformamide was added dropwise. After the addition was complete, the mixture was stirred and reacted at 23-25°C for 10-14 h. The product was purified to obtain an amino-functionalized degradable antibacterial monomer. The mass ratio of the degradable antibacterial monomer, N,N-dimethylformamide, and the 6.3 wt% solution of mercaptoethylamine in N,N-dimethylformamide was (9.4-14.2):(120-150):(28.6-51.4).
3. The method for preparing the biodegradable antibacterial plastic according to claim 1, characterized in that, In step one, the method for preparing the modified honokiol is as follows: Magnolol and triethylamine were dissolved in dichloromethane and stirred at 0-5℃ for 10-20 min. Then, a 17.18 wt% solution of chloroacetyl chloride in dichloromethane was added. After the addition was complete, the mixture was stirred at 0-5℃ for 40-60 min and then at 23-25℃ for 6-10 h. The product was purified to obtain modified magnolol.
4. The method for preparing the biodegradable antibacterial plastic according to claim 3, characterized in that, The mass ratio of magnolol, triethylamine, dichloromethane, a 17.18 wt% dichloroacetyl chloride solution in dichloromethane, and deionized water is (6.5-13):(4.9-9.8):(100-200):(64-128):(30-50).
5. The method for preparing the biodegradable antibacterial plastic according to claim 1, characterized in that, In step two, the method for preparing the hydroxyl-capped PBS is as follows: Succinic acid and 1,4-butanediol were mixed in a molar ratio of (1-2):(1.2-2.4), stirred, and esterified at 178-182℃ for 3.5-4.5 h. Then, 0.1% of tetrabutyl titanate was added, the temperature was raised to 210-230℃, and a vacuum of 36-44 Pa was applied. The reaction was carried out for 40-80 min. After the reaction was completed, the mixture was cooled and discharged to obtain hydroxyl-terminated PBS.
6. The method for preparing the biodegradable antibacterial plastic according to claim 1, characterized in that, In step three, the method for preparing the antibacterial modified PBS is as follows: Amino-functionalized degradable antibacterial monomer and hexamethylene diisocyanate were added to N,N-dimethylformamide and reacted under nitrogen atmosphere at 58-62℃ for 4-6 hours with stirring. The product was purified to obtain the modified degradable antibacterial monomer. The mass ratio of the amino-functionalized degradable antibacterial monomer, hexamethylene diisocyanate and N,N-dimethylformamide was (11-22):(3.4-6.8):(200-300). Hydroxyl-terminated PBS was added to chloroform, followed by the intermediate product and dibutyltin dilaurate. The mixture was stirred and reacted at 56-60°C for 5-7 hours under a nitrogen atmosphere. The product was purified to obtain antibacterial modified PBS. The mass ratio of the hydroxyl-terminated PBS, chloroform, intermediate product and dibutyltin dilaurate was (11.4-22.8):(250-350):(3.6-7.2):(0.05-0.09).
7. The method for preparing the biodegradable antibacterial plastic according to claim 1, characterized in that, In step four, the mass ratio of polylactic acid resin, antibacterial modified PBS, and organic modified antibacterial composite nanomaterial is (70-90):(10-30):(2-8).
8. The method for preparing the biodegradable antibacterial plastic according to claim 1, characterized in that, In step four, the preparation method of the organically modified antibacterial composite nanomaterial is as follows: Step S1: Mix 0.03 mol / L zinc acetate in ethanol, 0.05 mol / L copper nitrate in ethanol, 0.5 mol / L sodium hydroxide in ethanol, and titanium dioxide nanosheets in a ratio of (5-10) mL:(1-2) mL:(35-70) mL:(0.2-0.4) g, stir to form a suspension; react the suspension at 170-190℃ for 20-30 h; after the reaction is complete, centrifuge, wash, dry, and then calcine at 350-400℃ for 3-4 h to obtain antibacterial composite nanomaterials; Step S2: Mix 25wt% ammonia, deionized water, and ethanol in a mass ratio of (3.2-6.4):(50-100):(120-240), then add antibacterial composite nanomaterials, sonicate, and then add 3-(2,3-epoxypropoxy)propyltrimethoxysilane and ethanol. React at 60-70℃ for 2-3 hours with stirring, purify the product, and obtain functionalized antibacterial composite nanomaterials; wherein the mass ratio of the antibacterial composite nanomaterials to 3-(2,3-epoxypropoxy)propyltrimethoxysilane is (2.5-4.5):(0.3-0.9); Chitosan was added to N,N-dimethylformamide and stirred, then functionalized antibacterial composite nanomaterials were added, and the reaction was continued at 80-90℃ for 20-28 h. The product was purified to obtain organically modified antibacterial composite nanomaterials. The mass ratio of chitosan, N,N-dimethylformamide and functionalized antibacterial composite nanomaterials was (1.5-3.5):(150-300):(0.8-1.2).
9. The method for preparing the biodegradable antibacterial plastic according to claim 1, characterized in that, The preparation method of the titanium dioxide nanosheets: Tetraisopropyl titanate was added to isopropanol to obtain a precursor solution; distilled water was added to the precursor solution, stirred, and the pH was adjusted to 1.8-2.
2. Then, the solution was heated to 66-74℃ and maintained for 18-24 h to purify the product and obtain titanium hydroxide; wherein, the mass ratio of tetraisopropyl titanate, isopropanol and distilled water was (0.8-1.6):(12-24):(250-450); Titanium hydroxide was calcined at 390-410℃ for 1.5-2.5 h to obtain titanium dioxide nanosheets.
10. A biodegradable antimicrobial plastic prepared by the method for preparing biodegradable antimicrobial plastic as described in any one of claims 1-9.