CN109369941B

CN109369941B - Polylactic acid-polypyrrole/silver composite antibacterial film and preparation method thereof

Info

Publication number: CN109369941B
Application number: CN201811231183.2A
Authority: CN
Inventors: 毛龙; 刘跃军; 姚进; 陈剑洪; 刘静怡; 郑思洁
Original assignee: Xiamen University of Technology
Current assignee: Xiamen Ameson New Material Inc
Priority date: 2018-10-22
Filing date: 2018-10-22
Publication date: 2021-06-08
Anticipated expiration: 2038-10-22
Also published as: CN109369941A

Abstract

The invention provides a preparation method of a polylactic acid-polypyrrole/silver composite antibacterial film, and relates to the technical field of high polymer materials. The preparation method comprises the following steps: obtaining a PLA film; preparation of AgNO₃Aqueous solution, placing the PLA film on the AgNO₃Soaking and adsorbing in water solution; preparing Py monomer solution, pouring the Py monomer solution into the mixed solution, and adding Ag⁺And initiating the Py monomer to generate oxidation polymerization reaction on the surface of the PLA film to obtain the composite antibacterial film. It has excellent heat stability and antibacterial performance. In addition, the invention also relates to a polylactic acid-polypyrrole/silver composite antibacterial film, which comprises a PLA film matrix and a PPy/Ag composite antibacterial coating covering the surface of the PLA film matrix. The preparation method is simple, has low cost, and has certain research significance in the field of PLA active packaging.

Description

Polylactic acid-polypyrrole/silver composite antibacterial film and preparation method thereof

Technical Field

The invention relates to the field of high polymer materials, and in particular relates to a polylactic acid-polypyrrole/silver composite antibacterial film and a preparation method thereof.

Background

Polylactic acid (PLA) material is a biodegradable polymer material with excellent biocompatibility and physical properties, and has excellent biocompatibility and rigidity. PLA has great application potential in the field of packaging, can replace traditional plastic packaging materials to a certain extent, and relieves the current increasingly serious environmental pollution problem. However, PLA has certain defects in its barrier properties, antibacterial properties, etc., and further improvement is required.

Research shows that the conductive polymer material can also achieve an antibacterial effect through electrostatic interaction and other modes, so that the conductive polymer material and bacteria with negatively charged surfaces can be utilized to generate strong electrostatic combination effect so as to achieve an antibacterial effect. Among them, polypyrrole (PPy) has received wide attention due to its advantages of high electrical conductivity, good thermal stability, easy synthesis, excellent biocompatibility, and the like. However, in practical applications, PPy is limited by poor mechanical properties and processability, and in order to improve the performance of PPy, many studies have been made on the formation of an effective coating by in-situ polymerization of Py on the surface of a material for the purpose of surface modification.

Meanwhile, silver series antibacterial materials are a class of inorganic antibacterial materials. The inorganic silver-carrying antibacterial material has the characteristics of sustainability, durability, broad spectrum, good heat resistance, high safety, difficult generation of drug resistance and the like. Silver ions have excellent biological bactericidal action and exhibit a remarkable broad-spectrum antibacterial property. The silver ion has the 'micro-action effect' of killing pathogens and preventing the pathogens from proliferating and has higher biological antibacterial activity. Meanwhile, the silver-based antibacterial agent has better biocompatibility and safety. Silver nanoparticles are currently the most promising inorganic antibacterial materials, and silver ions released from unstable silver nanoparticles have excellent biological bactericidal effect, however, silver nanoparticles are high in cost and prone to agglomeration due to high surface area to volume ratio.

Disclosure of Invention

The invention aims to provide a polylactic acid-polypyrrole/silver composite antibacterial film which has excellent thermal stability and antibacterial property.

Another object of the present invention is to provide a method for preparing a polylactic acid-polypyrrole/silver composite antibacterial film, which uses Ag⁺The Py is initiated to be oxidized on the surface of the PLA film to form a composite antibacterial coating (PPy/Ag), the method is simple, and the cost is low.

The technical problem to be solved by the invention is realized by adopting the following technical scheme.

The invention provides a preparation method of a polylactic acid-polypyrrole/silver composite antibacterial film, which comprises the following steps:

s1, obtaining a PLA film;

s2 preparation of AgNO₃Aqueous solution, placing the PLA film on the AgNO₃Soaking and adsorbing in the aqueous solution to obtain a mixed solution;

s3, preparing Py monomer solution, pouring the Py monomer solution into the mixed solution, and adding Ag⁺And initiating the Py monomer to generate oxidation polymerization reaction on the surface of the PLA film to obtain the composite antibacterial film.

Further, the AgNO₃The concentration of the aqueous solution is 0.01-0.1mol/L, the concentration of the Py monomer solution is 0.05-0.5 mol/L, AgNO₃The molar ratio of Py to Py is 1: 3-5.

Further, in step S2, the temperature of the mixed solution is raised to 50 to 80 ℃, and the mixed solution is soaked and adsorbed for 10 to 30 min.

Further, in step S3, the Py monomer solution preparation step includes adding Py monomer into the aqueous solution, and magnetically stirring or ultrasonically treating for 5-10 min.

Further, in step S3, after the Py monomer solution is poured into the mixed solution, the mixture is magnetically stirred for 20-60 min.

Further, step S3 further includes: and after the polymerization reaction is finished, washing and drying the composite antibacterial film.

Further, the steps of washing and drying the composite antibacterial film comprise: and washing the composite antibacterial film with deionized water, and then blowing and drying for 5-20 h at 50-80 ℃.

Further, the step of obtaining the PLA film comprises: dissolving PLA in a solvent to obtain a PLA solution, transferring the PLA solution into a horizontally placed mold, and drying to form a film.

Further, the step of dissolving the PLA in a solvent comprises: and (3) carrying out magnetic stirring for 3-5 h at room temperature, and then carrying out ultrasonic treatment for 15-30 min.

The invention provides a polylactic acid-polypyrrole/silver composite antibacterial film which is prepared according to the preparation method and comprises a PLA film matrix and a PPy/Ag composite antibacterial coating covering the surface of the PLA film matrix.

The polylactic acid-polypyrrole/silver composite antibacterial film and the preparation method thereof have the beneficial effects that:

the PPy antibacterial coating is synthesized on the surface of the polylactic acid (PLA) which is a degradable high polymer material with excellent biocompatibility, and the conductive high polymer material achieves an antibacterial effect through modes such as an electrostatic effect and the like and generates a strong electrostatic combination effect with bacteria with negative electricity on the surface so as to achieve an antibacterial effect.

By using Ag⁺Initiating Py to generate chemical oxidation reaction on the PLA surface to synthesize PPy antibacterial coating, Ag⁺The Ag is reduced into the simple substance, and the Ag and the PPy are compounded to form the composite antibacterial coating, so that the high-cost nano silver is replaced, and the antibacterial performance of the PLA film is enhanced.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a flow chart of a method for preparing a polylactic acid-polypyrrole/silver composite antibacterial film provided by the invention;

fig. 2 is a thermogravimetric curve of the polylactic acid-polypyrrole/silver composite antibacterial film provided in example 1 of the present invention;

FIG. 3 is a scanning electron microscope image of the surface of the PLA-PPy/Ag composite antibacterial film in example 2 of the present invention;

FIG. 4 is an EDS energy spectrum of a PLA-PPy/Ag synthetic antibacterial film in example 2 of the present invention;

fig. 5 is a graph comparing the antibacterial activities of the pure PLA film of comparative example 1, the PPy antibacterial powder of comparative example 2, and the PLA-PPy/Ag composite antibacterial film of example 3 according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. Wherein pyrrole (Py): AR with a purity of not less than 99.7%, manufactured by Shanghai Allantin Biotechnology Ltd. FeCl₃·6H₂O: AR with a purity of not less than 99.0%, manufactured by Shanghai Allantin Biotechnology Ltd. AgNO₃: AR, purity not less than 99.8%, Shanghai Aladdin Biotechnology Ltd; trichloromethane: AR, science, Inc. of Sjodro. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The polylactic acid-polypyrrole/silver composite antibacterial film and the preparation method thereof according to the embodiment of the present invention will be specifically described below.

The embodiment of the invention provides a preparation method of a polylactic acid-polypyrrole/silver composite antibacterial film, which comprises the following steps:

s1, obtaining a PLA film;

In the preparation process, Ag⁺As an oxidant, Py monomer is polymerized to form PPy, during which process Ag⁺Is reduced to form Ag simple substance and is compounded with PPy to form a composite antibacterial coating which is coated on the surface of the PLA filmThe noodle has double antibacterial effects.

Further, in a preferred embodiment of the present invention, the AgNO is₃The concentration of the aqueous solution is 0.01-0.1mol/L, and the concentration of the Py monomer solution is 0.05-0.5 mol/L. When AgNO₃When the concentration of the solution is too low, the redox reaction is insufficient, PPy cannot be fully polymerized, and the reduction amount of the Ag simple substance is less; when the concentration of the Py monomer solution is too low, the formation of the composite antibacterial coating is not facilitated, and the antibacterial performance of the composite antibacterial coating is affected. When AgNO₃Excess AgNO when the concentration and Py monomer solution concentration are too high₃Run-off, to some extent, results in material waste and increased costs. Preferably, AgNO₃The molar ratio of Py to Py is 1: 3-5. More preferably, AgNO₃And Py in a molar ratio of 1: 4.8. Under the proportion, the antibacterial coating on the surface of the composite antibacterial film has a compact structure, the waste of materials is avoided, and meanwhile, the thermal stability and the antibacterial capability of the composite antibacterial film are obviously improved.

Further, in step S2, the temperature of the mixed solution is raised to 50-80 ℃, and the mixed solution is soaked and adsorbed for 10-30 min. At high temperatures, the efficiency of adsorption and the rate of subsequent oxidative polymerization reactions are further enhanced.

Further, in step S3, the Py monomer solution preparation step includes adding Py monomer into the aqueous solution, and because pyrrole is slightly soluble in water, the pyrrole can be sufficiently dissolved by magnetic stirring or ultrasound for 5-10 min to form Py aqueous solution.

Further, in step S3, after the Py monomer solution is poured into the mixed solution, the mixture is magnetically stirred for 20-60 min. Ensure the Ag adsorbed on the surface of the Py and PLA film in the Py aqueous solution⁺Fully reacting, and polymerizing in situ on the surface of the PLA film to form the PPy antibacterial coating.

The conductive polymer material can achieve an antibacterial effect through electrostatic interaction and other modes, and comprises polyaniline, polythiophene, polypyrrole, polyfuran and the like. Therefore, the conductive polymer material and the negatively charged bacteria on the surface can be utilized to generate strong electrostatic combination action so as to achieve the bacteriostatic effect. Among conductive polymers, polypyrrole (PPy) has the advantages of high conductivity, good thermal stability, easy synthesis, excellent biocompatibility and the like. Pyrrole (Py) monomers can form PPy by chemical oxidation or electrochemical polymerization in organic solvents or aqueous media. The Py can be utilized to form an effective coating on the surface of the material in situ polymerization to achieve the purpose of surface modification. The PPy backbone formed by oxidative polymerization generates positive charges, the substantial structure of which is similar to that of quaternary ammonium salts and benzoquinone, and both have positively charged N ions, thereby inhibiting the propagation of bacteria by electrostatic action.

Further, the step of dissolving the PLA in a solvent comprises: and (3) carrying out magnetic stirring for 3-5 h at room temperature, and then carrying out ultrasonic treatment for 15-30 min. In the dissolving process, a suitable solvent can be selected according to the molecular weight of the selected PLA, and examples thereof include tetrahydrofuran, chloroform, ethyl acetate, dichloromethane, and chloroform. Preferably, the solvent used is chloroform, which is more soluble and less toxic.

The features and properties of the present invention are described in further detail below with reference to examples.

Example 1

This example provides a polylactic acid-polypyrrole/silver composite antibacterial film, which is prepared according to the following steps.

(1) Weighing 2g of PLA, dissolving in 40ml of trichloromethane, magnetically stirring at room temperature for 4h, dissolving completely, performing ultrasonic treatment for 30min until no obvious bubbles exist, transferring the solution into a horizontally placed polytetrafluoroethylene mold, and naturally drying to form a film, wherein the length and the width of the PLA film are 60mm multiplied by 60 mm.

(2) 0.068g of AgNO₃Dissolving in 40ml deionized water, stirring thoroughly and ultrasonic treating for 5min to obtain AgNO₃Aqueous solution, immersing PLA film in AgNO₃And (3) obtaining a mixed solution in the aqueous solution, heating the mixed solution to 70 ℃, and adsorbing the PLA film in the solution for 30 min.

(3) 0.625ml of Py is measured and dissolved in 40ml of deionized water, and the solution is fully dissolved by ultrasonic treatment for 10 min.

(4) Transferring the Py solution into the mixed solution, and magnetically stirring for 60min to fully react.

(5) And (3) rinsing the composite antibacterial film for three times by using deionized water, and then drying the composite antibacterial film for 12 hours by blowing in an oven at the temperature of 60 ℃ to obtain the composite antibacterial film.

Example 2

(2) 0.32g of AgNO₃Dissolving in 40ml deionized water, stirring thoroughly and ultrasonic treating for 5min to obtain AgNO₃Aqueous solution, immersing PLA film in AgNO₃And (3) obtaining a mixed solution in the aqueous solution, heating the mixed solution to 80 ℃, and adsorbing the PLA film in the solution for 30 min.

Example 3

(2) 0.68g of AgNO₃Dissolving in 40ml deionized water, stirring thoroughly and ultrasonic treating for 5min to obtain AgNO₃Aqueous solution, immersing PLA film in AgNO₃And (3) obtaining a mixed solution in the aqueous solution, heating the mixed solution to 50 ℃, and adsorbing the PLA film in the solution for 30 min.

(3) 0.5ml of Py is measured and dissolved in 40ml of deionized water, and the solution is fully dissolved by ultrasonic treatment for 10 min.

Comparative example 1

This example provides a PLA film, which is made according to the following steps.

Comparative example 2

This example provides a polypyrrole antimicrobial powder, which was prepared according to the following procedure.

(1) 0.51g FeCl₃Dissolving in 40ml deionized water, fully stirring and carrying out ultrasonic treatment for 5min to obtain FeCl₃An aqueous solution.

(2) 0.625ml of Py is measured and dissolved in 40ml of deionized water, and the solution is fully dissolved by ultrasonic treatment for 10 min.

(3) Transferring Py solution to FeCl₃In the water solution, the mixture is magnetically stirred for 60min to fully react.

(4) And (3) blowing and drying the reacted mixed solution in an oven at 60 ℃ for 12h to obtain PPy powder.

(5) Respectively washing the PPy powder with absolute ethyl alcohol and deionized water, and then carrying out vacuum drying at 60 ℃ for 24h to obtain the polypyrrole antibacterial powder.

Comparative example 3

This example provides a polylactic acid-polypyrrole antibacterial film, which is prepared according to the following steps.

(2) 0.51g FeCl₃Dissolving in 40ml deionized water, fully stirring and carrying out ultrasonic treatment for 5min to obtain FeCl₃Aqueous solution, immersing PLA film in FeCl₃Obtaining mixed liquid in the water solution, and adsorbing the PLA film in the solution for 30 min.

(5) And (3) rinsing the composite antibacterial film for three times by using deionized water, and then drying the composite antibacterial film for 12 hours by blowing in an oven at the temperature of 60 ℃ to obtain the polylactic acid-polypyrrole antibacterial film.

Comparative example 4

(1) Weighing 2g of PLA, dissolving in 40ml of trichloromethane, magnetically stirring at room temperature for 4h, and performing ultrasonic treatment for 30min until no obvious bubbles exist.

(2) 0.625ml of pyrrole monomer is weighed and added into the polylactic acid solution, and the mixture is stirred for 2 hours to obtain a mixed solution.

(3) 0.68g of AgNO₃Dissolving in 40ml deionized water, stirring thoroughly and ultrasonic treating for 5min to obtain AgNO₃An aqueous solution.

(4) Mixing AgNO₃And dropwise adding the aqueous solution into the mixed solution, stirring, carrying out oxidative polymerization for 4 hours, transferring into a horizontally placed polytetrafluoroethylene mold, and naturally drying to form a film, thereby obtaining the polylactic acid-polypyrrole/silver composite antibacterial film.

Test example 1

FIG. 2 is a thermogravimetric curve of the polylactic acid-polypyrrole/silver composite antibacterial film provided in example 1 of the present invention, and it can be seen from the figure that T of PLA_-5％At 302.7 ℃ and T_-50％355.2 ℃ is adopted; t of PLA-PPy/Ag multilayer film at the same time_-5％At 317.3 ℃ C, T_-50％At 357.3 ℃ T compared to PLA film_-5％The increase amplitude reached 14.6 ℃. Because PPy has higher thermal stability, the PPy can better play a role in heat insulation and is helpful for delaying the thermal degradation temperature of PLA. This shows that the thermal stability of the composite antibacterial film existing in the PPy layer is obviously improved, and the service performance of the PLA film is improved.

Test example 2

Diluting the Escherichia coli bacterial suspension by using an LB liquid culture medium until the absorbance value of 600nm is-0.1, sucking 0.1ml of bacterial suspension, uniformly coating the bacterial suspension on the LB liquid culture medium, adding the PLA-PPy/Ag composite antibacterial film obtained in the example 2 into a centrifuge tube containing sterilized distilled water, soaking for 24 hours, placing the centrifuge tube on the surface of a bacteria-containing culture medium, culturing for 16 hours at 37 ℃, and measuring the size of a bacteriostatic ring to determine the antibacterial activity. Wherein the diameter of the film was 10mm, and the antibacterial results are shown in FIG. 3.

Fig. 3 is a scanning electron microscope image of the surface of the PLA-PPy/Ag composite antibacterial film in example 2 of the present invention, and it can be seen from fig. 3 that the surface of the PLA-PPy/Ag composite antibacterial film appears as flakes. EDS scanning is carried out on the PLA-PPy/Ag composite antibacterial film, and an EDS energy spectrum diagram is obtained and is shown in figure 4. As can be seen from fig. 4, Ag element is present in addition to N element present in PPy, indicating that these Ag element are mainly present in these platelets and the mass fraction of Ag reaches 17.2%.

Test example 3

FIG. 5 shows the results of the E.coli antimicrobial tests of a pure PLA film (comparative example 1), PPy (comparative example 2), and a PLA-PPy/Ag composite antimicrobial film (example 3). As can be seen from fig. 5(a), the pure PLA film did not show zone of inhibition, indicating that PLA has no discernible antimicrobial properties. The pure PPy powder in FIG. 5(b) shows a clear zone of inhibition at Ag⁺Ag while acting as an oxidant to initiate polymerization of Py⁺Is reduced into Ag simple substance which is gathered around PPyPPy and Ag with antibacterial properties exist at the same time, so that the double antibacterial effect is achieved, and the PLA-PPy/Ag multilayer composite film has an obvious antibacterial ring, which shows that the PLA-PPy/Ag multilayer composite film has better antibacterial performance.

In order to further quantitatively evaluate the antibacterial performance of the PLA-PPy/Ag antibacterial film, the colony numbers of culture dishes soaked with different films are counted by a colony counter, the antibacterial activities of a pure PLA film (comparative example 1), a PLA-PPy antibacterial film (comparative example 3), a PLA-PPy/Ag composite antibacterial film (example 3) and a PLA-PPy/Ag composite antibacterial film (comparative example 4) are evaluated according to the colony numbers, specifically, an Escherichia coli strain is inoculated into an LB solid culture medium by an inoculating loop and cultured for 24 hours in an incubator at 37 ℃. Inoculating the grown colony in LB liquid culture medium, performing constant temperature shaking culture at 37 deg.C for 24 hr in constant temperature shaking bed, diluting with LB liquid culture medium, and adjusting the concentration of corresponding bacteria to 1 × 10⁸CFU// mL, then continued in LB liquid medium for 12h after the suspension diluted until 600nm absorbance value of-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 the film samples (diameter is 10mm) into a conical flask containing bacterial liquid respectively to make the film fully soaked in the bacterial liquid, performing constant temperature shaking culture at 37 ℃ for 24h, coating the film on a solid culture medium, and placing the film in a constant temperature culture shaking table to continue the culture for 24h, wherein the results are shown in Table 1.

TABLE 1 antimicrobial Activity data for example 3, comparative example 1, comparative example 3, and comparative example 4

	Bacterial concentration (CFU/cm)²)
		Example 3	2.9×10⁶
Comparative example 1	4.8×10¹⁰
		Comparative example 3	6.2×10⁷
Comparative example 4	4.3×10⁹

As can be seen from Table 1, the bacterial concentration of the pure PLA film reached 4.8X 10¹⁰CFU/cm². The bacterial concentration of the PLA-PPy/Ag composite antibacterial film provided by the comparative example 4 reaches 4.3 multiplied by 10⁹CFU/cm². After PPy is subjected to surface coating, the bacteria concentration of the PLA-PPy antibacterial film is reduced to 6.2 multiplied by 10⁷CFU/cm². In the PPy coating with Ag, the bacteria concentration is further reduced to 2.9X 10⁶CFU/cm². Compared with a pure PLA film, the bacteria concentration is reduced by more than 4 orders of magnitude, which shows that the PLA-PPy/Ag multilayer composite film shows excellent antibacterial activity.

The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Claims

1. A preparation method of a polylactic acid-polypyrrole/silver composite antibacterial film is characterized by comprising the following steps:

s1, obtaining a PLA film;

s2 preparation of AgNO₃Aqueous solution, placing the PLA film on the AgNO₃Soaking and adsorbing in the aqueous solution to obtain a mixed solution; wherein the temperature of the mixed solution is increased to 50-80 ℃, and the mixed solution is soaked and adsorbed for 10-30 min;

s3, preparing Py monomer solution, pouring the Py monomer solution into the mixed solution, and magnetically stirring for 20-60 min to obtain Ag⁺And initiating the Py monomer to generate oxidation polymerization reaction on the surface of the PLA film to obtain the composite antibacterial film.

2. The method for preparing polylactic acid-polypyrrole/silver composite antibacterial film according to claim 1, wherein the AgNO is₃The concentration of the aqueous solution is 0.01-0.1mol/L, the concentration of the Py monomer solution is 0.05-0.5 mol/L, AgNO₃The molar ratio of Py to Py is 1: 3-5.

3. The method for preparing a polylactic acid-polypyrrole/silver composite antibacterial film according to claim 1, wherein in step S3, the step of preparing the Py monomer solution includes: adding Py monomer into the aqueous solution, and magnetically stirring or ultrasonically treating for 5-10 min.

4. The method for preparing a polylactic acid-polypyrrole/silver composite antibacterial film according to claim 1, wherein the step S3 further includes: and after the polymerization reaction is finished, washing and drying the composite antibacterial film.

5. The method for preparing a polylactic acid-polypyrrole/silver composite antibacterial film according to claim 4, wherein the steps of washing and drying the composite antibacterial film comprise: and washing the composite antibacterial film with deionized water, and then blowing and drying for 5-20 h at 50-80 ℃.

6. The method for preparing a polylactic acid-polypyrrole/silver composite antibacterial film according to claim 1, wherein the step of obtaining the PLA film comprises: dissolving PLA in a solvent to obtain a PLA solution, transferring the PLA solution into a horizontally placed mold, and drying to form a film.

7. The method for preparing a polylactic acid-polypyrrole/silver composite antibacterial film according to claim 6, wherein the step of dissolving the PLA in the solvent comprises: and (3) carrying out magnetic stirring for 3-5 h at room temperature, and then carrying out ultrasonic treatment for 15-30 min.

8. A polylactic acid-polypyrrole/silver composite antibacterial film is characterized by being prepared according to the preparation method of any one of claims 1 to 7, and comprising a PLA film substrate and a PPy/Ag composite antibacterial coating covering the surface of the PLA film substrate.