Stereoscopic composite polylactic acid antibacterial and mosquito-repellent fiber loaded with natural plant micropowder and its preparation method
By using β-cyclodextrin-encapsulated plant micropowders and PLLA/PDLA stereocomposite spinning technology in textiles, the problems of active ingredient loss and weakened mechanical properties in mosquito-repellent textiles have been solved, achieving a highly efficient and safe mosquito-repellent effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANTONG UNIV
- Filing Date
- 2026-03-31
- Publication Date
- 2026-06-26
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention belongs to the field of functional textile materials technology, specifically relating to a stereocomposite polylactic acid antibacterial and mosquito-repellent fiber loaded with natural plant micropowder and its preparation method. Background Technology
[0002] Currently, imparting mosquito-repellent properties to textiles mainly relies on finishing processes such as chemical impregnation and spraying. However, these methods present a dilemma: on the one hand, the functional components rely solely on physical adhesion to the fiber surface, lacking a strong chemical or physical bond. This makes the active ingredients easily detach during friction and washing, resulting in a rapid decline in mosquito-repellent efficacy and failing to meet the long-term use requirements in outdoor and medical settings. On the other hand, to compensate for the insufficient adhesion of finishing processes, the industry often introduces excessive amounts of organic cross-linking agents or adhesives. The residue of these auxiliaries not only damages the ecological properties of bio-based fibers, but more importantly, when mosquito-repellent fabrics are worn close to the skin or used as medical protective materials, the residual chemical agents can easily induce physiological risks such as skin allergies and inflammation.
[0003] Adding natural plant powders such as artemisia, lavender, and mint to spinning solutions is an effective way to improve the environmental friendliness of textile materials. However, the introduction of powder particles often weakens the mechanical properties of the fiber materials. In addition, the aforementioned finishing processes usually involve high-temperature treatment, which can easily destroy the bioactivity of natural heat-sensitive functional components.
[0004] In summary, existing mosquito-repellent finishing technologies struggle to achieve a balance between dependence on chemical auxiliaries and safety, washability, retention of fiber mechanical properties, and preservation of natural active ingredients. Therefore, a key technical challenge urgently needs to be overcome: how to achieve efficient immobilization of functional components through structured physical locking methods while avoiding excessive chemical adhesives and high-temperature processing, and simultaneously ensuring the retention of the fiber matrix's mechanical properties and bioactivity. Summary of the Invention
[0005] To address the shortcomings and deficiencies of the existing technologies, this invention provides a stereocomposite polylactic acid antibacterial and mosquito-repellent fiber loaded with natural plant micropowder and its preparation method. By optimizing the solvent system design and using low-temperature solution spinning technology, the contradiction between "high-temperature preparation" and "activity retention" is resolved.
[0006] In a first aspect, the present invention provides a method for preparing a stereocomposite polylactic acid antibacterial and mosquito-repellent fiber loaded with natural plant microparticles, comprising the following steps:
[0007] S1. Dissolve polylactic acid (PLLA) and polylactic acid (PDLA) in organic solvents respectively to prepare PLLA solution and PDLA solution, and disperse plant micropowder encapsulated with β-cyclodextrin in at least one of PLLA solution and PDLA solution;
[0008] S2. The PLLA solution and PDLA solution prepared in step S1 are mixed and spun immediately to obtain nascent fibers;
[0009] S3. The nascent fibers are subjected to heat treatment to induce the formation of stereocomposite crystals, thereby obtaining stereocomposite polylactic acid fibers loaded with natural plant micropowder.
[0010] In some embodiments of the present invention, in step S1, the organic solvent is at least one of dichloromethane, N,N-dimethylformamide, chloroform, trifluoroacetic acid, and hexafluoroisopropanol.
[0011] In some embodiments of the present invention, the mass ratio of L-polylactic acid to D-polylactic acid in the spinning solution is (40-60):(40-60).
[0012] In some embodiments of the present invention, in step S1, the method for preparing the plant micro powder is as follows: the dried plant raw materials are mixed and processed by air jet milling or high-energy ball milling to obtain plant micro powder with a particle size of less than 5 μm.
[0013] In some embodiments of the present invention, in step S1, the plant materials include mugwort, lavender and mint.
[0014] In some embodiments of the present invention, in step S2, the spinning is electrospinning; the process conditions are: temperature 22℃-26℃, relative humidity 30%-40%, receiving distance 15-20 cm, spinning flow rate 1.0-2.0 mL / h, and voltage 15-25 kV.
[0015] In some embodiments of the present invention, in step S2, the spinning is wet spinning; the process conditions are: coagulation bath temperature 20℃-25℃; the mixed spinning solution is extruded into the coagulation bath through the spinneret orifice for solidification; the coagulation bath component is anhydrous ethanol / methanol.
[0016] In some embodiments of the present invention, in step S3, the heat treatment conditions are as follows: the nascent fibers are first dried in a vacuum oven at 40°C-60°C for 10-12 hours; then heat-treated at 100°C-120°C for 10-20 minutes.
[0017] In a second aspect, the present invention provides an antibacterial and mosquito-repellent three-dimensional composite polylactic acid fiber loaded with natural plant microparticles, prepared by the above-described preparation method.
[0018] In some embodiments of the present invention, the antibacterial and mosquito-repellent three-dimensional composite polylactic acid fiber loaded with natural plant micropowder has an antibacterial rate of greater than 95% and a mosquito-repellent rate of greater than 80%.
[0019] A third aspect of the present invention provides the application of the above-mentioned antibacterial and mosquito-repellent three-dimensional composite polylactic acid fiber loaded with natural plant micropowder in high-end functional textiles for summer, outdoor protective equipment and medical protective materials.
[0020] Compared with existing technologies, this invention pre-encapsulates mosquito-repellent plant powder with β-cyclodextrin to form a stable composite, which is then uniformly dispersed in at least one of polylactic acid (PLLA) and polylactic acid (PDLA) solutions. Based on this, utilizing the characteristic that PLLA and PDLA undergo stereocomposite crystallization at low temperatures, the encapsulated material is coated into a stereocomposite network structure. Subsequent heat treatment at a mild temperature of 100–120°C is sufficient to achieve the final shaping of the fiber structure. This low-temperature processing route effectively avoids the damage to heat-sensitive plant active ingredients caused by traditional high-temperature processes, significantly preserving the mosquito-repellent efficacy. Simultaneously, the resulting stereocomposite structure endows the fiber with excellent mechanical properties, avoiding the material embrittlement problem caused by the addition of plant micropowder. Detailed Implementation
[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] Unless otherwise specified below, the specifications and manufacturer information of all raw materials used in the various embodiments of this application are commercially available:
[0023] L-polylactic acid and D-polylactic acid were purchased from Shenzhen Guanghua Weiye; chloroform, N,N-dimethylformamide, β-cyclodextrin, polyvinyl alcohol, and KH-550 silane coupling agent were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; dried Artemisia argyi, lavender, and peppermint powder were purchased from Bozhou Traditional Chinese Medicine Wholesale Market in Anhui Province; and anhydrous ethanol was purchased from Shanghai Lingfeng Chemical Reagent Co., Ltd.
[0024] This invention provides a method for preparing stereocomposite polylactic acid antibacterial and mosquito-repellent fibers loaded with natural plant microparticles, comprising the following steps:
[0025] Example 1 (Electrospinning method)
[0026] S1. Precursor Preparation: 4.5 g of L-polylactic acid and 4.5 g of D-polylactic acid were dissolved in 50 mL of a mixture of chloroform and N,N-dimethylformamide to prepare PLLA and PDLA solutions, respectively. Artemisia argyi, lavender, and peppermint were ground into plant micro-powders with a particle size of 500-1000 nm. 37.50 g of the plant micro-powder, after high-energy ball milling, was completely dissolved in 112.50 g of anhydrous ethanol to prepare a 25% (w / w) natural powder solution. Simultaneously, 52.50 g of β-cyclodextrin, 296.45 g of distilled water, and 1.05 g of polyvinyl alcohol (as an emulsifier) were placed in a container and thoroughly mixed to obtain a β-cyclodextrin emulsion. Subsequently, the natural powder solution was slowly added to the emulsion in the reactor, stirring was started, and the pH of the system was adjusted to 5. The mixture was stirred and infused at a constant temperature of 20-40℃ for 2 hours. After the reaction, the resulting emulsion was filtered and washed with deionized water. The solid product was placed in a vacuum drying oven and dried at 35°C and 40°C for 12 hours each (total time 24 hours) to obtain dried β-cyclodextrin inclusion complex powder. 1.0 g of the inclusion complex powder was added to a PLLA solution and dispersed using an ultrasonic homogenizer for 30 minutes, with sonication for 2-3 seconds followed by a 2-4 second pause.
[0027] S2. Electrospinning: A PLLA solution containing inclusion complex micropowder is mixed with a PDLA solution and continuously stirred at room temperature until it becomes a clear and homogeneous spinning solution. The spinning solution is transferred to a syringe equipped with a metal needle, and air bubbles in the air chamber are removed. The syringe is then fixed to a micro-injection pump. A feed rate of 25 μL / min is used, a DC voltage of 22 kV is applied between the needle and the aluminum foil roller, the receiving distance is 15 cm, the relative humidity is 40±2%, and the temperature is 24±2℃ to obtain nascent fibers.
[0028] S3. Post-treatment: The nascent fibers were placed in a vacuum oven at 60°C and heat-treated for 10 h. Subsequently, they were heat-treated in a forced-air oven at 120°C for 10 min to prepare the sample of Example 1.
[0029] Example 2 (Wet spinning method)
[0030] S1. Precursor Preparation: 4.5 g of L-polylactic acid and 4.5 g of D-polylactic acid were dissolved in 50 mL of a mixture of chloroform and N,N-dimethylformamide to prepare PLLA and PDLA solutions, respectively. Artemisia argyi, lavender, and peppermint were ground into plant micro-powders with a particle size of 500-1000 nm. 37.50 g of the plant micro-powder, after high-energy ball milling, was completely dissolved in 112.50 g of anhydrous ethanol to prepare a 25% (w / w) natural powder solution. Simultaneously, 52.50 g of β-cyclodextrin, 296.45 g of distilled water, and 1.05 g of polyvinyl alcohol (as an emulsifier) were thoroughly mixed in a container to obtain a β-cyclodextrin emulsion. The natural powder solution was then slowly added to the emulsion in the reactor. Stirring was started, and the pH of the system was adjusted to 5. The mixture was stirred and infused at a constant temperature of 20-40℃ for 2 hours. After the reaction, the resulting emulsion was filtered and washed with deionized water. The solid product was placed in a vacuum drying oven and dried at 35°C and 40°C for 12 hours each (total time 24 hours) to obtain dried β-cyclodextrin inclusion complex powder. 1.0 g of the inclusion complex powder was added to a PLLA solution and dispersed using an ultrasonic homogenizer for 30 minutes, with sonication for 2-3 seconds followed by a 2-4 second pause.
[0031] S2. Wet spinning: A PLLA solution containing inclusion complex powder is mixed with a PDLA solution and continuously stirred at room temperature until it becomes a clear and homogeneous spinning solution. The mixture is then rapidly extruded through a spinneret (0.08 mm orifice) into a methanol coagulation bath at 25°C to obtain nascent filaments.
[0032] S3. Post-treatment: After the nascent yarn is wound, it is stretched four times in a 90°C hot water bath, and then heat-treated in a 120°C forced-air oven for 10 min. The sample of Example 2 is prepared.
[0033] Comparative Example 1 (Melt spinning method)
[0034] S1. β-Cyclodextrin Encapsulation Treatment: Artemisia argyi, lavender, and peppermint were ground into plant micro-powders with a particle size of 500-1000 nm. 37.50 g of the plant micro-powder, obtained through high-energy ball milling, was completely dissolved in 112.50 g of anhydrous ethanol to prepare a 25% (w / w) natural powder solution. Simultaneously, 52.50 g of β-cyclodextrin, 296.45 g of distilled water, and 1.05 g of polyvinyl alcohol (as an emulsifier) were thoroughly mixed in a container to obtain a β-cyclodextrin emulsion. The natural powder solution was then slowly added to the emulsion in the reactor. Stirring was started, and the pH of the system was adjusted to 5. The mixture was continuously stirred and encapsulated at a constant temperature of 20-40℃ for 2 hours. After the reaction, the resulting emulsion was filtered and washed with deionized water. The solid product was placed in a vacuum drying oven and dried at 35℃ and 40℃ for 12 hours each, finally obtaining dried β-cyclodextrin inclusion complex micro-powder.
[0035] S2. Pre-blending and dispersion: PLLA and PDLA chips were dried in an 80℃ vacuum drying oven for 12 h to reduce their moisture content to below 100 ppm. The dried polymer chips were pre-blended with the inclusion complex powder and KH-550 silane coupling agent in a high-speed mixer. The mixture was then added to a twin-screw extruder and subjected to preliminary shear dispersion at 220℃ to ensure uniform distribution of the plant powder in the polymer matrix.
[0036] S3. Melt spinning: The pre-blended material is added to a melt spinning machine. The spinning assembly temperature is set to 240℃, the screw speed to 75 rpm, the assembly pressure to 10 MPa, and the ambient humidity to 40±2%. After the melt is extruded through the spinneret, it is solidified by a cooling air blowing device at a cooling temperature of 22℃ and a side-blowing air velocity of 0.45 m / s. The nascent fibers are collected by a winding device to obtain nascent blended fibers loaded with plant inclusion complexes.
[0037] S4. Post-processing: The nascent fibers were stretched online using heated rollers at a temperature of 100°C for 3 seconds, resulting in a stretch ratio of 3.5 times. The stretched fibers were then subjected to isothermal heat setting in a hot air oven at 160°C for 20 seconds, producing the sample for Comparative Example 1.
[0038] Comparative Example 2 (Ordinary PLLA fiber without PDLA)
[0039] The only difference from Example 1 is that PDLA was not added (PLLA was used entirely), and the sample of Example 2 was prepared.
[0040] Test Example 1
[0041] The antibacterial rate of Examples 1-2 and Comparative Examples 1-2 was tested using the absorption method. 0.1 g of UV-sterilized fiber samples were placed in a sterile petri dish, and 100 μL of E. coli suspension with a concentration of approximately 1 × 10⁶ CFU / mL was added, ensuring complete absorption of the droplet. After incubation at 37°C for 24 hours, residual bacteria were collected by shaking with elution buffer and plate cultured for counting. The percentage of inhibition was calculated. The test results are shown in Table 1.
[0042] Test Example 2
[0043] The mosquito repellency performance of the samples from Examples 1-2 and Comparative Examples 1-2 was tested using a closed laboratory repellency method. During the test, 0.1 g of fiber sample was fixed to the back of the subject's hand (exposed area 4 cm × 4 cm) and placed in a biological test chamber containing approximately 300 Aedes albopictus mosquitoes. The number of times mosquitoes landed on the sample surface within 2 minutes was recorded, and the repellency rate was calculated. Simultaneously, the sample was washed 50 times using a simulated household washing method, and the above test was repeated to evaluate the long-term effectiveness. The test results are shown in Table 1.
[0044] Test Example 3
[0045] The tensile strength and elongation at break of the samples from Examples 1-2 and Comparative Examples 1-2 were tested using an electronic single-fiber tensile tester. Before testing, each group of fibers was equilibrated for 24 hours under constant temperature and humidity conditions (20℃, 65% relative humidity). The spacing was set to 20 mm, the tensile speed to 20 mm / min, and 50 fibers were randomly selected from each group of samples for testing, with the average value taken. The test results are shown in Table 1.
[0046] Test Example 4
[0047] The thermal properties of the samples from Examples 1-2 and Comparative Examples 1-2 of this invention were tested using differential scanning calorimetry (DSC). During testing, each group of fiber samples was weighed and placed in an aluminum crucible, heated from 40°C to 250°C at a heating rate of 10°C / min under nitrogen protection. The melting endothermic peak temperature (Tm) and enthalpy of fusion in the scanning curves were recorded, and their stereocrystalline degree (%) was calculated. The results are shown in Table 1.
[0048] Test Example 5
[0049] For the heat resistance test, each group of fiber materials was cut into 10 cm × 10 cm pieces and placed in vacuum ovens at different temperatures (80℃, 120℃, 160℃) for 30 minutes. The changes in length and width of the samples before and after treatment were recorded, and the heat shrinkage rate was calculated. For (Example 2), the boiling water shrinkage rate test was performed. The results are shown in Table 1.
[0050] Table 1. Antibacterial rate, mosquito repellency rate, tensile strength, SC melting point, stereocomposite degree, and heat resistance test results for each sample.
[0051]
[0052] By comparing the various test data, it can be found that Example 1 shows good comprehensive performance in terms of antibacterial rate, mosquito repellency rate, tensile strength, melting point, stereocrystalline degree and heat resistance.
[0053] Comparing the data from Examples 1-2 and Comparative Examples 1-2, it can be seen that both Examples 1-2 and Comparative Examples 1-2 incorporated natural micro-powders encapsulated with β-cyclodextrin. In Comparative Example 1, the antibacterial and mosquito-repellent active ingredients in natural plants undergo severe thermal degradation or carbonization and inactivation under high-temperature conditions, leading to a significant decrease in the bioactivity of the final fiber product, and a marked reduction in its antibacterial and mosquito-repellent rates. Examples 1-2 and Comparative Example 1 successfully constructed stereocomposite crystal structures through blending induction of PLLA and PDLA. Due to the relatively low crystallinity of the stereocomposite in Example 2 and the lack of a stereocomposite structure in Comparative Example 2, the material lacks the support of a high-melting-point lattice when heated, and the intermolecular forces are weak. Therefore, Examples 2 and Comparative Example 2 exhibit a significant decrease in fracture strength and low high-temperature dimensional stability (heat resistance) macroscopically.
[0054] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing stereocomposite polylactic acid fibers loaded with natural plant micropowder, characterized in that, Includes the following steps: S1. Dissolve polylactic acid (PLLA) and polylactic acid (PDLA) in organic solvents respectively to prepare PLLA solution and PDLA solution, and disperse plant micropowder encapsulated with β-cyclodextrin in at least one of PLLA solution and PDLA solution; S2. The PLLA solution and PDLA solution prepared in step S1 are mixed and spun immediately to obtain nascent fibers; S3. The nascent fibers are subjected to heat treatment to induce the formation of stereocomposite crystals, thereby obtaining stereocomposite polylactic acid fibers loaded with natural plant micropowder.
2. The preparation method according to claim 1, characterized in that, In step S1, the organic solvent is at least one of dichloromethane, N,N-dimethylformamide, chloroform, trifluoroacetic acid, and hexafluoroisopropanol.
3. The preparation method according to claim 1, characterized in that, In the spinning solution, the mass ratio of L-polylactic acid to D-polylactic acid is (40-60):(40-60).
4. The preparation method according to claim 1, characterized in that, In step S1, the method for preparing the plant micro powder is as follows: the dried plant raw materials are mixed and processed by air jet milling or high-energy ball milling to obtain plant micro powder with a particle size of less than 5 μm.
5. The preparation method according to claim 4, characterized in that, In step S1, the plant materials include mugwort, lavender, and mint.
6. The preparation method according to claim 1, characterized in that, Step S2 specifically involves: the spinning is electrospinning; the process conditions are: temperature 22℃-26℃, relative humidity 30%-40%, receiving distance 15-20 cm, spinning flow rate 1.0-2.0 mL / h, and voltage 15-20 kV.
7. The preparation method according to claim 1, characterized in that, Step S2 specifically involves: the spinning is wet spinning; the process conditions are: coagulation bath temperature 20℃-25℃; the mixed spinning solution is extruded into the coagulation bath through the spinneret orifice for solidification; the coagulation bath composition is anhydrous ethanol / methanol.
8. The preparation method according to claim 1, characterized in that, In step S3, the heat treatment conditions are as follows: the nascent fibers are first dried in a vacuum oven at 40℃-60℃ for 10-12 hours; then heat-treated at 100℃-120℃ for 10-20 minutes.
9. A stereocomposite polylactic acid fiber loaded with natural plant microparticles prepared by the preparation method according to any one of claims 1-8.
10. The stereocomposite polylactic acid fiber loaded with natural plant micropowder according to claim 9, characterized in that, The melting point of the stereocomposite crystals in stereocomposite polylactic acid fiber is higher than 200℃.