阅读说明：本技术 一种LDHs@PLA复合功能薄膜及其制备方法 (LDHs @ PLA composite functional film and preparation method thereof ) 是由 陈章平 杨玲 于 2021-01-07 设计创作，主要内容包括：本发明公开了一种LDHs@PLA复合功能薄膜及其制备方法,包括将二价金属盐和三价金属盐加入到蒸馏水中,超声溶解,加入氢氧化钠和碳酸钠,强力搅拌,离心,洗涤转移至高压反应釜,在105～120℃下反应15～20h,冷却,离心,干燥得到LDHs纳米粒子；将壳聚糖加入冰醋酸溶液中,磁力搅拌,加入有机溶剂,室温搅拌,然后加入聚乳酸(PLA),搅拌4～8h未出现相分离后,冷冻干燥,得到凝胶；将硝酸银加入N,N-二甲基甲酰胺中,超声溶解,加入聚乳酸和LDHs纳米粒子,超声搅拌,将凝胶粉碎研磨,过800目网筛后加入,搅拌1～2h,移入静电纺丝注射泵,得到纤维膜；将该纤维膜平铺在玻璃皿上,倒入聚乳酸的N,N-二甲基甲酰胺溶液,刮涂均匀后,在真空干燥箱中90～100℃干燥,得到所述功能复合薄膜。(The invention discloses an LDHs @ PLA composite functional film and a preparation method thereof, which comprises the steps of adding divalent metal salt and trivalent metal salt into distilled water, ultrasonically dissolving, adding sodium hydroxide and sodium carbonate, strongly stirring, centrifuging, washing, transferring to a high-pressure reaction kettle, reacting for 15-20 h at 105-120 ℃, cooling, centrifuging, and drying to obtain LDHs nano particles; adding chitosan into a glacial acetic acid solution, stirring by magnetic force, adding an organic solvent, stirring at room temperature, then adding polylactic acid (PLA), stirring for 4-8 hours, and freeze-drying to obtain gel after no phase separation occurs; adding silver nitrate into N, N-dimethylformamide, ultrasonically dissolving, adding polylactic acid and LDHs nano particles, ultrasonically stirring, crushing and grinding gel, adding the gel after passing through a 800-mesh screen, stirring for 1-2 h, and transferring the gel into an electrostatic spinning injection pump to obtain a fiber membrane; and flatly spreading the fiber membrane on a glass dish, pouring an N, N-dimethylformamide solution of polylactic acid, uniformly scraping and coating, and drying in a vacuum drying oven at 90-100 ℃ to obtain the functional composite film.)

1. A preparation method of an LDHs @ PLA composite functional film is characterized by comprising the following steps:

s1: adding a divalent metal salt and a trivalent metal salt with a molar ratio of 2.1-2.6: 1 into distilled water, ultrasonically dissolving, strongly stirring sodium hydroxide and sodium carbonate for 20-30 min, centrifuging, washing the obtained precipitate with distilled water, dispersing the washed precipitate in deionized water, ultrasonically stirring for 10-30 min, transferring to a high-pressure reaction kettle, reacting at 105-120 ℃ for 15-20 h, cooling, centrifuging, and drying to obtain LDHs nano particles;

s2: adding chitosan into a glacial acetic acid solution, then carrying out magnetic stirring for 10-15 min, then adding an organic solvent, stirring for 30-45 min at room temperature, then adding polylactic acid (PLA), stirring for 4-8 h, standing for 1-2 h after no phase separation occurs, and freeze-drying for 2-4 days to obtain a gel;

s3: adding silver nitrate into N, N-dimethylformamide, ultrasonically dissolving, then adding polylactic acid and LDHs nano particles, ultrasonically stirring for 30-50 min, then crushing and grinding the gel obtained in the step S2, sieving with a 800-mesh sieve, adding into the solution, stirring for 1-2 h, transferring into an electrostatic spinning injection pump, and obtaining a fiber membrane on a receiving roller;

s4: and flatly spreading the fiber membrane on a glass dish, pouring an N, N-dimethylformamide solution of polylactic acid, uniformly scraping, and drying in a vacuum drying oven at 90-100 ℃ to obtain the functional composite film.

2. The method for preparing a LDHs @ PLA composite functional film as claimed in claim 1, wherein the organic solvent is 1, 4-dioxane; the volume ratio of the glacial acetic acid to the 1, 4-dioxane is (2-3) to (20-30).

3. The method for preparing LDHs @ PLA composite functional films as claimed in claim 1, wherein the glacial acetic acid is 55-60% by mass.

4. The method for preparing LDHs @ PLA composite functional film as claimed in claim 1, wherein the mass ratio of the chitosan to the polylactic acid is (1-1.6): (0.12-0.18).

5. The preparation method of the LDHs @ PLA composite functional film as claimed in claim 1, wherein the mass-to-volume ratio of the silver nitrate, the N, N-dimethylformamide, the polylactic acid and the LDHs nanoparticles is (1.5-1.8) g, (20-30) mL, (1.69-1.94) g, (2.24-2.46) g.

6. An LDHs @ PLA composite functional film, which is characterized by being prepared according to the preparation method of any one of claims 1 to 5.

Technical Field

The invention belongs to the technical field of functional film materials, and particularly relates to an LDHs @ PLA composite functional film and a preparation method thereof.

Background

Double hydroxide metal composite oxides, abbreviated as LDHs (layered double hydroxides), are anionic layered compounds, also known as Hydrotalcites (Hydrotalcites), and have acidic and basic characteristics, memory effect, interlayer anion exchangeability and microporous structure. Since 1970 the first patent on the preparation of hydrogenation catalysts from hydrotalcite-like compounds, hydrotalcite-like compounds have attracted considerable interest. Hydrotalcite layered column materials are widely applied to the fields of catalysis, adsorption, ion exchange and the like as a special material, and in recent years, with further research on the materials, the application of the hydrotalcite layered column materials in the aspects of medicines, coatings, pesticides, functional polymer materials, oil field development and the like is developed.

Polylactic acid (PLA) material, as a fully biodegradable aliphatic polyester, has excellent biocompatibility and stiffness. The linear thermoplastic biodegradable aliphatic polyester takes starch extracted from corn, wheat, cassava and other plants as an initial raw material, glucose is obtained by enzymatic decomposition, lactic acid is obtained by lactic acid bacteria fermentation, and then high-purity polylactic acid is obtained by chemical synthesis. PLA materials have good mechanical strength, thermoplasticity, fiber forming properties, transparency, etc., are suitable for various processing methods, and are considered to be the most ideal alternative material for petroleum-based plastics. Polylactic acid prepared from lactic acid can be degraded into carbon dioxide and water in natural environment through microorganisms, has no pollution to the environment, and is widely applied in the fields of medical, agricultural and general plastics and the like.

The antibacterial modification process of the polylactic acid is to mix the polylactic acid and the metal nanoparticles to improve the antibacterial performance of the PLA, so that the production and application can be better met. However, the metal nanoparticles have large specific surface area, extremely high surface energy, are very easy to agglomerate, are difficult to uniformly disperse during mixing modification, and have poor modification effect. Meanwhile, the metal particles can play an antibacterial role only by contacting with bacteria, if the metal particles are directly added into the polylactic acid substrate, only a small part of the metal particles on the surface of the substrate can play a role, and most of the metal particles wrapped in the substrate cannot play a due antibacterial effect due to an isolation effect.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a preparation method of an LDHs @ PLA composite functional film, which comprises the following steps:

s1: adding a divalent metal salt and a trivalent metal salt with a molar ratio of 2.1-2.6: 1 into distilled water, ultrasonically dissolving, strongly stirring sodium hydroxide and sodium carbonate for 20-30 min, centrifuging, washing the obtained precipitate with distilled water, dispersing the washed precipitate in deionized water, ultrasonically stirring for 10-30 min, transferring to a high-pressure reaction kettle, reacting at 105-120 ℃ for 15-20 h, cooling, centrifuging, and drying to obtain LDHs nano particles.

S2: adding chitosan into a glacial acetic acid solution, then carrying out magnetic stirring for 10-15 min, then adding an organic solvent, stirring for 30-45 min at room temperature, then adding polylactic acid (PLA), stirring for 4-8 h, standing for 1-2 h after no phase separation occurs, and freeze-drying for 2-4 days to obtain the gel.

S3: adding silver nitrate into N, N-dimethylformamide, ultrasonically dissolving, then adding polylactic acid and LDHs nano particles, ultrasonically stirring for 30-50 min, then crushing and grinding the gel obtained in the step S2, sieving with a 800-mesh sieve, adding into the solution, stirring for 1-2 h, transferring into an electrostatic spinning injection pump, and receiving on a roller to obtain the fiber membrane.

S4: and flatly spreading the fiber membrane on a glass dish, pouring an N, N-dimethylformamide solution of polylactic acid, uniformly scraping, and drying in a vacuum drying oven at 90-100 ℃ to obtain the functional composite film.

Preferably, the organic solvent is 1, 4-dioxane; the volume ratio of the glacial acetic acid to the 1, 4-dioxane is (2-3) to (20-30).

Preferably, the glacial acetic acid is 55-60% by mass.

Preferably, the mass ratio of the chitosan to the polylactic acid is (1-1.6): (0.12-0.18).

Preferably, the mass-to-volume ratio of the silver nitrate, the N, N-dimethylformamide, the polylactic acid and the LDHs nanoparticles is (1.5-1.8) g, (20-30) mL, (1.69-1.94) g and (2.24-2.46) g.

Compared with the prior art, the invention has the following beneficial effects:

according to the invention, chitosan and polylactic acid are prepared into gel, then the gel is compounded with LDHs nano particles and silver ions, and the fiber membrane is prepared by electrostatic spinning, so that the contact area with a polylactic acid solution is increased, wherein the chitosan/polylactic acid gel compounding effectively improves the mechanical properties (tear strength, elongation at break and the like) of the composite membrane, and simultaneously, the silver metal ions and the chitosan synergistically play an antibacterial role, so that the membrane has a better antibacterial effect.

Drawings

FIG. 1 is an SEM image of LDHs prepared in example 1 of the present invention.

Detailed Description

The following embodiments of the present invention are described in detail, and the embodiments are implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, it should be noted that, for those skilled in the art, a plurality of modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Example 1

A preparation method of an LDHs @ PLA composite functional film specifically comprises the following steps:

s1: adding magnesium chloride and aluminum chloride with a molar ratio of 2.1:1 into distilled water, carrying out ultrasonic dissolution, then carrying out strong stirring on sodium hydroxide and sodium carbonate for 20min, centrifuging, washing the obtained precipitate with distilled water, then dispersing the washed precipitate in deionized water, carrying out ultrasonic stirring for 10min, transferring to a high-pressure reaction kettle, reacting for 15h at 105 ℃, cooling, centrifuging, and drying to obtain the LDHs nano particles.

S2: adding chitosan into a glacial acetic acid solution with the mass fraction of 55%, magnetically stirring for 10min, adding 1, 4-dioxane, stirring at room temperature for 30min, adding polylactic acid (PLA), stirring for 4h without phase separation, standing for 1h, and freeze-drying for 2-4 days to obtain gel, wherein the mass ratio of the chitosan to the polylactic acid is 1: 0.12.

S3: adding silver nitrate into N, N-dimethylformamide, ultrasonically dissolving, then adding polylactic acid and LDHs nano particles, ultrasonically stirring for 30min, then crushing and grinding the gel in the step S2, adding the gel into the solution after passing through a 800-mesh screen, stirring for 1h, moving into an electrostatic spinning injection pump, injecting at the voltage of 10kV, the injection distance of 10cm and the injection rate of 2.2cm/h, and obtaining a fiber membrane on a receiving roller, wherein the mass-volume ratio of the silver nitrate, the N, N-dimethylformamide, the polylactic acid and the LDHs nano particles is 1.5g:20mL:1.69g:2.24 g.

S4: and spreading the fiber membrane on a glass dish, pouring an N, N-dimethylformamide solution of polylactic acid, uniformly scraping, and drying in a vacuum drying oven at 90 ℃ to obtain the functional composite film.

Example 2

A preparation method of an LDHs @ PLA composite functional film specifically comprises the following steps:

s1: adding magnesium chloride and aluminum chloride with a molar ratio of 2.6:1 into distilled water, carrying out ultrasonic dissolution, then carrying out strong stirring on sodium hydroxide and sodium carbonate for 30min, centrifuging, washing the obtained precipitate with distilled water, then dispersing the washed precipitate in deionized water, carrying out ultrasonic stirring for 30min, transferring to a high-pressure reaction kettle, carrying out reaction for 20h at 120 ℃, cooling, centrifuging, and drying to obtain the LDHs nano particles.

S2: adding chitosan into a glacial acetic acid solution with the mass fraction of 60%, magnetically stirring for 15min, adding 1, 4-dioxane, wherein the volume ratio of the glacial acetic acid to the 1, 4-dioxane is 3:30, stirring at room temperature for 45min, adding polylactic acid (PLA), stirring for 8h without phase separation, standing for 2h, and freeze-drying for 4 days to obtain gel, wherein the mass ratio of the chitosan to the polylactic acid is 1.6: 0.18.

S3: adding silver nitrate into N, N-dimethylformamide, ultrasonically dissolving, then adding polylactic acid and LDHs nano particles, ultrasonically stirring for 50min, then crushing and grinding the gel obtained in the step S2, adding the gel into the solution after passing through a 800-mesh screen, stirring for 2h, moving into an electrostatic spinning injection pump, injecting at the voltage of 13kV, the injection distance of 12cm and the injection rate of 2.5cm/h, and obtaining a fiber membrane on a receiving roller, wherein the mass-volume ratio of the silver nitrate to the N, N-dimethylformamide to the polylactic acid to the LDHs nano particles is 1.8g to 30mL to 1.94g to 2.46 g.

S4: and spreading the fiber membrane on a glass dish, pouring an N, N-dimethylformamide solution of polylactic acid, uniformly scraping, and drying in a vacuum drying oven at 100 ℃ to obtain the functional composite film.

Example 3

A preparation method of an LDHs @ PLA composite functional film specifically comprises the following steps:

s1: adding magnesium chloride and aluminum chloride with a molar ratio of 2.3:1 into distilled water, carrying out ultrasonic dissolution, then carrying out strong stirring on sodium hydroxide and sodium carbonate for 25min, centrifuging, washing the obtained precipitate with distilled water, then dispersing the washed precipitate in deionized water, carrying out ultrasonic stirring for 20min, transferring to a high-pressure reaction kettle, reacting for 17h at 110 ℃, cooling, centrifuging, and drying to obtain the LDHs nano particles.

S2: adding chitosan into a glacial acetic acid solution with the mass fraction of 56%, magnetically stirring for 12min, adding 1, 4-dioxane, wherein the volume ratio of the glacial acetic acid to the 1, 4-dioxane is 2.3:25, stirring at room temperature for 35min, adding polylactic acid (PLA), stirring for 6h without phase separation, standing for 1.5h, and freeze-drying for 3 days to obtain gel, wherein the mass ratio of the chitosan to the polylactic acid is 1.2: 0.14.

S3: adding silver nitrate into N, N-dimethylformamide, ultrasonically dissolving, then adding polylactic acid and LDHs nano particles, ultrasonically stirring for 40min, then crushing and grinding the gel in the step S2, adding the gel into the solution after passing through a 800-mesh screen, stirring for 1.5h, moving into an electrostatic spinning injection pump, injecting at the voltage of 11kV, the injection distance of 11cm and the injection rate of 2.3cm/h, and obtaining a fiber membrane on a receiving roller, wherein the mass-volume ratio of the silver nitrate to the N, N-dimethylformamide to the polylactic acid to the LDHs nano particles is 1.6g:25mL:1.77g:2.32 g.

S4: and spreading the fiber membrane on a glass dish, pouring an N, N-dimethylformamide solution of polylactic acid, uniformly scraping, and drying in a vacuum drying oven at 95 ℃ to obtain the functional composite film.

Example 4

A preparation method of an LDHs @ PLA composite functional film specifically comprises the following steps:

s1: adding magnesium chloride and aluminum chloride with a molar ratio of 2.5:1 into distilled water, carrying out ultrasonic dissolution, then carrying out strong stirring on sodium hydroxide and sodium carbonate for 30min, centrifuging, washing the obtained precipitate with distilled water, then dispersing the washed precipitate in deionized water, carrying out ultrasonic stirring for 25min, transferring to a high-pressure reaction kettle, reacting at 115 ℃ for 18h, cooling, centrifuging, and drying to obtain the LDHs nano particles.

S2: adding chitosan into a glacial acetic acid solution with the mass fraction of 55-60%, magnetically stirring for 14min, adding 1, 4-dioxane, wherein the volume ratio of the glacial acetic acid to the 1, 4-dioxane is 2.8:25, stirring for 40min at room temperature, adding polylactic acid (PLA), stirring for 7h without phase separation, standing for 2h, and freeze-drying for 3 days to obtain gel, wherein the mass ratio of the chitosan to the polylactic acid is 1.5: 0.16.

S3: adding silver nitrate into N, N-dimethylformamide, ultrasonically dissolving, then adding polylactic acid and LDHs nano particles, ultrasonically stirring for 40min, then crushing and grinding the gel obtained in the step S2, adding the gel into the solution after passing through a 800-mesh screen, stirring for 2h, moving into an electrostatic spinning injection pump, injecting at the voltage of 12kV, the injection distance of 12cm and the injection rate of 2.4cm/h, and obtaining a fiber membrane on a receiving roller, wherein the mass-volume ratio of the silver nitrate to the N, N-dimethylformamide to the polylactic acid to the LDHs nano particles is 1.7g to 28mL to 1.92g to 2.44 g.

S4: and spreading the fiber membrane on a glass dish, pouring an N, N-dimethylformamide solution of polylactic acid, uniformly scraping, and drying in a vacuum drying oven at 100 ℃ to obtain the functional composite film.

Comparative example 1

A pure polylactic acid film.

Comparative example 2

A composite film prepared according to the method described in example 1 in chinese patent document CN 110408183A.

Examples of the experiments

Performance test-mechanical property test: tensile strength, elongation at break and tear strength tests were performed on the composite films prepared in examples 1 to 4 and the films in comparative examples 1 to 2 according to the GB/T1040.3-2008 standard, and the test results are shown in Table 1;

the antibacterial rate test of the composite films prepared in examples 1-4 and the films in comparative examples 1-2 adopts a flat plate colony counting method as an antibacterial performance test method, and the antibacterial object is gram-negative bacteria-escherichia coli. The preserved strain was inoculated into LB solid medium through an inoculating loop and cultured in an incubator at 37 ℃ for 24 hours. The grown colonies were inoculated in LB liquid medium and shake-cultured in a constant temperature incubator shaker at 37 ℃ for 24 hours. Diluting LB liquid culture medium, and adjusting the absorbance to 0.1 by a spectrophotometer, namely the corresponding bacteria concentration is 1 x 10⁸CFU/mL. Culturing the bacteria in LB liquid culture medium for 12h, and diluting the bacterial suspension to 600nm^-1The absorbance value was-0.1. 150 μ L of the inoculum was dropped into a conical flask containing 15mL of liquid medium at a inoculum concentration of 1X 10⁵CFU/mL. Soaking a film sample with a disc with the diameter of 10mm into a conical flask containing bacterial liquid to enable the sample to be fully soaked in the bacterial liquid, then placing the conical flask into a constant-temperature shaking table at 37 ℃ for shaking culture for 24 hours, then taking a proper amount of diluted bacterial liquid and coating the diluted bacterial liquid on a culture dish, placing the diluted bacterial liquid in the constant-temperature shaking table for continuous culture for 24 hours, counting the number of bacterial colonies on the culture dish through a bacterial colony counter, and evaluating the antibacterial activity of the sample through the antibacterial rate, wherein the antibacterial rate is [ (number of bacterial colonies in comparison-number of bacterial colonies in sample)/number of bacterial colonies in comparison [ ]]X 100%, the results are shown in Table 1;

the flame retardant performance of the composite films prepared in examples 1 to 4 and the films in comparative examples 1 to 2 was characterized by limiting oxygen index and maximum smoke density performance tests, the results of which are shown in Table 1,

table 1. results of performance testing:

as can be seen from the results in Table 1, the composite functional films prepared in the examples 1 to 4 of the invention have tensile strength of about 34.6MPa, elongation at break of about 187% and tear strength of about 286N, and have excellent mechanical properties compared with the composite films in the comparative examples 1 to 2, and meanwhile, the antibacterial rate of the films prepared in the examples 1 to 4 can reach more than 44.9, and the films in the comparative examples 1 to 2 have more excellent antibacterial properties, and the films of the invention also have better flame retardant property according to the results of the limit epoxy index and maximum smoke density performance tests.