Preparation method of quaternary ammonium salt copolymer compatibilized PLA-PBAT antibacterial composite material

Abstract

The present invention relates to a preparation method of a quaternary ammonium salt copolymer compatibilized PLA-PBAT antibacterial composite material, belonging to the technical field of polymer synthesis. In the present invention, three quaternary ammonium salts with different carbon chain lengths are synthesized as antibacterial monomers, and then a copolymer containing maleic anhydride groups is obtained as a compatibilizer through copolymerization. Finally, a polymer containing quaternary ammonium salt, i.e., an antibacterial compatibilizer, is obtained through ion exchange. Then, the prepared antibacterial compatibilizer is melt-blended with PLA and PBAT to prepare a quaternary ammonium salt copolymer compatibilized PLA-PBAT antibacterial composite material, and the strength and elongation at break of the composite material are both significantly improved, and excellent antibacterial properties are exhibited.

Description

Technical Field

[0001] The present invention relates to a preparation method of a quaternary ammonium salt copolymer compatibilized PLA-PBAT antibacterial composite material, belonging to the technical field of polymer synthesis. Background Art

[0002] With the intensification of the global "white pollution", countries around the world have implemented plastic restriction orders to reduce the dependence on and use of petroleum-based plastic products. In order to fundamentally solve this problem, scientific researchers have developed biodegradable materials to replace the existing petroleum-based plastics. Biodegradable materials are environmentally friendly materials that can be decomposed by microorganisms in the natural environment, and the end products are water, carbon dioxide and have no pollution to the environment.

[0003] Currently, the more common biodegradable materials on the market include polylactic acid (PLA), poly(butylene adipate-co-terephthalate) (PBAT), polycaprolactone (PCL), poly(butylene succinate) (PBS), and polyhydroxyalkanoates (PHAs), etc. The raw material of PLA is lactic acid, which is mainly synthesized from biomass resources such as corn starch. It is one of the representatives of bio-based biodegradable plastics and has complete biodegradability. Among many biodegradable materials, PLA is one of the most studied, produced and commercially successful biodegradable polymers at present. However, the disadvantages of low melt strength and poor toughness of PLA limit its application to a certain extent. Therefore, PLA needs to be modified to improve its processing performance. At present, improving the processing performance of PLA through toughening modification is the research focus. Since PBAT has good tensile properties and flexibility, it is considered a good candidate for toughening PLA. Therefore, melt blending of PBAT and PLA is an effective way to improve the brittleness of PLA and enhance the processing performance of PLA. However, melt blending of PLA and PBAT is a physical modification, and the properties of the blend depend on the compatibility effect of the two blends. Since the mechanical properties of the PLA / PBAT blend system are not ideal. Only by screening a suitable compatibilizer to reduce the interfacial tension between the PLA and PBAT phases and improve the interfacial adhesion can a modified material with excellent comprehensive properties be prepared. Therefore, the compatibility between PLA and PBAT is a key factor affecting the properties of the composite material. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a quaternary ammonium salt copolymer compatibilized PLA-PBAT antibacterial composite material.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A preparation method of a quaternary ammonium salt copolymer compatibilized PLA-PBAT antibacterial composite material, characterized by comprising the following steps:

[0007] (1) Preparation of compatibilizing copolymer PSM

[0008] Sodium 4-styrenesulfonate and maleic anhydride are reacted in the presence of AIBN and DMF under N2 protection to prepare the compatibilizing copolymer PSM;

[0009] (2) Preparation of antibacterial compatibilizer

[0010] The prepared compatibilizing polymer PSM, quaternary ammonium salt ionic liquid, and DMF are stirred at room temperature until fine particles precipitate, then centrifuged to remove the precipitated solid, and the polymer containing quaternary ammonium salt, i.e., the antibacterial compatibilizer, is obtained;

[0011] (3) Preparation of PLA-PBAT antibacterial composite material

[0012] The PLA and PBAT masterbatches are vacuum dried before use, and then the antibacterial compatibilizer prepared in step (2) is blended with PLA and PBAT particles, and after blending, it is pelletized to obtain the PLA-PBAT antibacterial composite material.

[0013] Further settings are as follows:

[0014] In step (1):

[0015] Under N2 protection, the reaction temperature is 70 - 90 °C, and the reaction time is 24 - 72 h. Preferably, the reaction is carried out at 80 °C for 72 h.

[0016] In step (2):

[0017] The quaternary ammonium salt ionic liquid is any one of imidazolium ionic liquid [C4MIM]Br, imidazolium ionic liquid [C8MIM]Br, and imidazolium ionic liquid [C 12 MIM]Br.

[0018] Among them:

[0019] The imidazolium ionic liquid [C4MIM]Br is prepared by the following method: 1-methylimidazole, 1-bromobutane, and methanol are stirred until completely dissolved, then stirred at room temperature for reaction. After the reaction, it is washed and filtered by suction to obtain the imidazolium ionic liquid [C4MIM]Br.

[0020] The imidazolium ionic liquid [C8MIM]Br is prepared by the following method: 1-methylimidazole, 1-bromooctane, and methanol are stirred until completely dissolved, then stirred at room temperature for reaction. After the reaction, it is washed and filtered by suction to obtain the imidazolium ionic liquid [C8MIM]Br.

[0021] Imidazolium ionic liquid monomer [C 12MIM]Br was prepared by the following method: 1-methylimidazole, 1-bromododecane and methanol were stirred until completely dissolved, and then stirred at room temperature for reaction. After the reaction, it was washed and filtered by suction to obtain the imidazolium ionic liquid [C 12 MIM]Br.

[0022] The prepared compatibilizing polymer PSM, quaternary ammonium salt ionic liquid and DMF were stirred at room temperature until fine particles precipitated, and then centrifuged to remove the precipitated solid. Then, it was stirred for 12 h and centrifuged again, and the process was repeated until no solid precipitated from the solution. The solution was dropped into an ethyl acetate solution for sedimentation, filtered by suction, and the obtained solid was dried to obtain the antibacterial compatibilizer.

[0023] In step (3):

[0024] Both the PLA and PBAT masterbatches need to be dried in a vacuum drying oven at 80 °C for 12 h before use.

[0025] The dosage of the antibacterial compatibilizer is 1-5 phr (based on the PLA and PBAT masterbatches), and preferably 3 phr of the antibacterial compatibilizer is added.

[0026] The antibacterial compatibilizer is blended with PLA / PBAT particles, and the processing temperature is 170 °C and the rotation speed is 50 rpm.

[0027] The beneficial effects of the present invention are as follows:

[0028] (1) In the present invention, three quaternary ammonium salts with different carbon chain lengths are synthesized as antibacterial monomers, and then a copolymer containing maleic anhydride groups is obtained as a compatibilizer by copolymerization. Finally, a polymer containing quaternary ammonium salt, i.e., the antibacterial compatibilizer, is obtained by ion exchange. According to the experimental results, after adding 3 phr of the antibacterial compatibilizer and melt-blending with PLA and PBAT, the prepared quaternary ammonium salt copolymer compatibilizes the PLA-PBAT antibacterial composite material, and both the strength and elongation at break of the composite material are significantly improved. And excellent antibacterial properties are exhibited.

[0029] (2) The applicant further found through experiments that the quaternary ammonium salt polymers with three alkyl chain lengths are melt-blended with PLA / PBAT to obtain the PLA / PBAT / antibacterial compatibilizer composite material, and their mechanical properties and antibacterial properties are different. At the same time, the addition amount of the antibacterial compatibilizer has a significant impact on the properties of the composite material. Through experiments, it is found that the composite material with 3 phr of the antibacterial compatibilizer added has the best performance.

[0030] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Brief Description of the Drawings

[0031] Figure 1 For [C4MIM]Br prepared by the present invention1 1H NMR spectrum (CDCl3).

[0032] Figure 2 1H NMR spectrum (CDCl3) of [C8MIM]Br prepared according to the present invention. 1 1H NMR spectrum (CDCl3).

[0033] Figure 3 1H NMR spectrum (CDCl3) of [C 12 MIM]Br prepared according to the present invention. 1 1H NMR spectrum (CDCl3).

[0034] Figure 4 Infrared spectrum of the compatibilizing copolymer PSM prepared according to the present invention.

[0035] Figure 5 Infrared spectra of the antibacterial compatibilizers PBSM, POSM, and PDSM prepared according to the present invention.

[0036] Figure 6 Infrared spectra of the PLA / PBAT, PLA / PBAT / PBSM, PLA / PBAT / POSM, and PLA / PBAT / PDSM composites prepared according to the present invention.

[0037] Figure 7 a Schematic diagram of the mechanical properties of the PLA / PBAT / PBSM composite prepared according to the present invention.

[0038] Figure 7 b Schematic diagram for comparing the mechanical properties of the PLA / PBAT / PBSM, PLA / PBAT / POSM, and PLA / PBAT / PDSM composites prepared according to the present invention.

[0039] Figure 8 Schematic diagram of the notched impact strength of the PLA / PBAT / PBSM composite prepared according to the present invention.

[0040] Figure 9 Schematic diagram of the effect of the quaternary ammonium salt copolymer prepared according to the present invention on the antibacterial properties of the composite material. Detailed implementation manners

[0041] The materials and reagents used in the examples of the present invention are as follows:

[0042] PLA particles (Mw = 19.8×104 g mol-1, Mn = 1.96, melting point = 164.3 °C), supplied by Suzhou Jinquan New Materials Co., Ltd. PBAT particles (Mw = 8.4×104 g mol-1, melting point = 126.7 °C), supplied by Shanghai Tongcheng Chemical Co., Ltd. Methanol, N,N-dimethylformamide (DMF), and ethyl acetate (EA) were all purchased from Aladdin. 1-Bromobutane, 1-bromooctane, and 1-bromododecane were purchased directly without further purification. Azobisisobutyronitrile (AIBN) was recrystallized. 1-Methylimidazole, sodium 4-styrenesulfonate, and maleic anhydride (MAH) were purchased from Macklin without further purification.

[0043] The instruments used in this invention are as follows:

[0044] The structures of the materials were characterized using a nuclear magnetic resonance spectrometer AVANCE AV400 MHz (Bruker, Switzerland) and a Fourier transform infrared spectrometer Nicolet 5700 (Thermo Fisher Scientific, USA). The mechanical properties of the materials were tested using a tensile testing machine MOXIN MX-0350 (Jiangsu Moxin Industrial System Co., Ltd., China). Dynamic mechanical thermal analysis of the materials was performed using a dynamic mechanical analyzer Q800 (TA, USA).

[0045] Example 1: Preparation of imidazolium ionic liquid monomer [C4MIM]Br

[0046] Add 1-methylimidazole (9.8324 g, 0.119 mol), 1-bromobutane (13.8245 g, 0.1 mol), and anhydrous methanol (30 ml) to a 250 mL round-bottom flask. After stirring until completely dissolved, connect an air stopper to the upper opening and stir the reaction at room temperature for 72 h. After the reaction, wash with ethyl acetate and ether three times and filter by suction. Transfer to a vacuum oven for drying to obtain the imidazolium ionic liquid monomer [C4MIM]Br, with a yield of 95.3%.

[0047] Product confirmation: The 1 1H NMR spectrum (CDCl3) of [C4MIM]Br is as Figure 1 shown.

[0048]

[0049] Example 2: Preparation of imidazolium ionic liquid monomer [C8MIM]Br

[0050] Add 1-methylimidazole (9.4325 g, 0.114 mol), 1-bromooctane (19.5468 g, 0.1 mol) and anhydrous methanol (30 ml) into a 250 mL round-bottom flask. After stirring until completely dissolved, connect an air plug to the upper opening and stir the reaction at room temperature for 72 h. After the reaction is completed, wash it 3 times with ethyl acetate and diethyl ether, filter by suction, and transfer it to a vacuum oven for drying to obtain the imidazolium ionic liquid monomer [C8MIM]Br, yield: 81.3%.

[0051] Product confirmation: The 1 1H NMR spectrum of [C8MIM]Br (CDCl3) is as Figure 2 shown.

[0052]

[0053] Example 3: Preparation of imidazolium ionic liquid monomer [C 12 MIM]Br

[0054] Add 1-methylimidazole (9.6451 g, 0.117 mol), 1-bromododecane (25.0201 g, 0.1 mol) and anhydrous methanol (30 ml) into a 250 mL round-bottom flask. After stirring until completely dissolved, connect an air plug to the upper opening and stir the reaction at room temperature for 72 h. After the reaction is completed, wash it 3 times with diethyl ether, filter by suction, and transfer the obtained white powder to a vacuum oven for drying to obtain the imidazolium ionic liquid monomer [C 12 MIM]Br, yield: 84.9%.

[0055] Product confirmation: The 12 1H NMR spectrum of [C 1 MIM]Br (CDCl3) is as Figure 3 shown.

[0056]

[0057] Example 4: Preparation of compatibilizing copolymer PSM

[0058] Add sodium 4-styrenesulfonate (20.6325 g, 0.1 mol), maleic anhydride (9.9275 g, 0.1 mol), AIBN (0.3532 g) and DMF (120 ml) into a 250 mL round-bottom flask. After stirring until completely dissolved. After the solution is evacuated and purged with N2 in 3 cycles, stir the reaction at 80 °C for 72 h under N2 protection. After the reaction is completed, wash it 3 times with ethyl acetate and then filter by suction. Transfer the obtained light yellow solid powder to a vacuum oven for drying to obtain the compatibilizing copolymer poly(sodium styrenesulfonate-maleic anhydride), abbreviated as: PSM, yield: 91.32%.

[0059] Product confirmation: The infrared spectrum of the compatibilizing copolymer PSM is asFigure 4 as shown

[0060]

[0061] Example 5: Preparation of Antibacterial Compatibilizer PBSM

[0062] Add compatibilizing polymer PSM (21.6325 g), [C4MIM]Br (15.5928 g, 0.071 mol) and DMF (80 ml) into a 250 mL round-bottom flask. Stir at room temperature until fine particles precipitate. Centrifuge to remove the precipitated sodium bromide solid, then stir for 12 h and centrifuge again. Repeat until no solid precipitates in the solution. Drop the solution into ethyl acetate solution for sedimentation, filter by suction, and dry the obtained solid to get the antibacterial compatibilizer Polymeric(1-Butyl-3-methylimidazolium Styrenesulfonate-Maleic anhydride) PBSM, yield: 78.24%.

[0063] Product confirmation: The infrared spectrum of antibacterial compatibilizer PBSM is as Figure 5 shown

[0064]

[0065] Example 6: Preparation of Antibacterial Compatibilizer POSM

[0066] Add compatibilizing polymer PSM (21.6325 g), [C8MIM]Br (19.4681 g, 0.0707 mol) and DMF (80 ml) into a 250 mL round-bottom flask. Stir at room temperature until fine particles precipitate. Centrifuge to remove the precipitated sodium bromide solid, then stir for 12 h and centrifuge again. Repeat until no solid precipitates in the solution. Drop the solution into ethyl acetate solution for sedimentation, filter by suction, and dry the obtained solid to get the antibacterial compatibilizer Polymeric(1-Octyl-3-methylimidazolium Styrenesulfonate-Maleic anhydride) POSM. Yield: 81.24%.

[0067] Product confirmation: The infrared spectrum of antibacterial compatibilizer POSM is as Figure 5 shown

[0068]

[0069] Example 7: Preparation of Antibacterial Compatibilizer PDSM

[0070] Add the compatibilizing polymer PSM (21.6325 g), [C 12 MIM]Br (23.2014 g, 0.07 mol) and DMF (100 ml) into a 250 mL round-bottom flask. Stir at room temperature until fine particles precipitate. Centrifuge to remove the precipitated sodium bromide solid, then stir for 12 h and centrifuge again. Repeat until no solid precipitates from the solution. Drop the solution into ethyl acetate solution for sedimentation, filter by suction, and dry the obtained solid to get the antibacterial compatibilizer poly(1-dodecyl-3-methylimidazolium styrenesulfonate-maleic anhydride) PDSM. Yield: 80.18%.

[0071] Product confirmation: The infrared spectrum of the antibacterial compatibilizer PDSM is as Figure 5 shown.

[0072]

[0073] Example 8: Preparation of PLA / PBAT / antibacterial compatibilizer composite

[0074] Both PLA and PBAT masterbatches need to be dried in a vacuum drying oven at 80 °C for 12 h before use. Blend the antibacterial compatibilizer PBSM (3 phr) with PLA / PBAT particles (70 / 30) respectively. Set the processing temperature at 170 °C and the rotation speed at 50 rpm. Granulate after blending to obtain the PLA / PBAT / PBSM (70 / 30 / 3) composite. Injection-molded specimens are used for subsequent tests and characterizations.

[0075] Replacement Example 1:

[0076] The preparation method is the same as that in Example 8, except that the dosage of the antibacterial compatibilizer PBSM is adjusted to 1 / 2 / 4 / 5 phr respectively to prepare the PLA / PBAT / PBSM (70 / 30 / 1), PLA / PBAT / PBSM (70 / 30 / 2), PLA / PBAT / PBSM (70 / 30 / 4), and PLA / PBAT / PBSM (70 / 30 / 5) composites respectively.

[0077] Replacement Example 2:

[0078] The preparation method is the same as that in Example 8, except that the antibacterial compatibilizer PBSM is replaced with POSM and PDSM to prepare the PLA / PBAT / POSM composite and the PLA / PBAT / PDSM composite respectively, and they are compared with PLA / PBAT prepared without adding antibacterial compatibilizer.

[0079] Product structure characterization:

[0080] Figure 5 The infrared spectra of the antibacterial compatibilizers PBSM, POSM, and PDSM prepared in this invention are shown as follows: Figure 5 As shown, the stretching vibration peak of the imidazole structure in the ionic liquid is at 1568 / 1487 cm -1 and the symmetric vibration peak of S=O in the sulfonic acid group of sodium 4-styrenesulfonate corresponds to 1120 / 1180 cm -1 ; the stretching vibration peak of C=O in MAH corresponds to 1770 cm -1 , indicating the successful preparation of the antibacterial compatibilizers PBSM, POSM, and PDSM.

[0081] Figure 6 The infrared spectra of the PLA / PBAT, PLA / PBAT / PBSM, PLA / PBAT / POSM, and PLA / PBAT / PDSM composites prepared in Example 8 and Replacement Example 2 are shown as follows: Figure 6 As shown, in the infrared spectra of the three composites of PLA / PBAT / PBSM, PLA / PBAT / POSM, and PLA / PBAT / PDSM, it is found that the C=O peak of MAH at 1770 cm -1 disappears, and the C=O peaks of the original PLA and PBAT phases show a red shift, proving that the antibacterial compatibilizer undergoes a chain extension reaction with the terminal hydroxyl groups of PLA and PBAT.

[0082] Product mechanical property test:

[0083] For the composites prepared in Example 8, Replacement Example 1, and Replacement Example 2, the product mechanical property tests were carried out respectively according to the following methods:

[0084] Impact specimens were prepared using a micro-injection molding machine to obtain dumbbell-shaped specimens with dimensions of 18.0×3.0×0.50 mm 3 (length, width, and thickness). The specimens were tested using a universal material testing machine at room temperature with a tensile speed of 50 mm / min. And a notched impact test was carried out using an impact testing machine with a pendulum energy of 5 J, and the data were recorded as shown in Figure 7 , Figure 8 .

[0085] Figure 7a shows the effect of different PBSM addition amounts on the elongation at break of the product: Adding the antibacterial compatibilizer PBSM to the PLA / PBAT composite can effectively improve the elongation at break of the composite, which can reflect that the compatibility of the composite has been effectively improved from the side. The elongation at break of the composite with 1 phr PBSM added is increased to 53%, and when 3 phr PBSM is added, the elongation at break reaches the maximum value of 111%. Compared with the composite without the antibacterial compatibilizer PBSM added, the elongation at break is increased by 6.5 times.

[0086] Figure 7 b shows the effect of different antibacterial compatibilizers PBSM, POSM, and PDSM on the elongation at break of the product: As can be seen from Figure 7 b, the long-chain alkyl group also has the effect of improving the compatibility of the two phases. The long-chain alkyl group can penetrate into the PLA or PBAT phase and entangle with the molecular chains, thereby improving the interfacial force between the two phases. Among them, the elongation at break of the composite with 3 phr antibacterial compatibilizer PDSM added can reach up to 126%.

[0087] Figure 8 shows the effect of different PBSM addition amounts on the notched impact strength of the product: The notched impact strength can also reflect the toughness of the material. As can be seen from Figure 8 : When the composite with 3 phr antibacterial compatibilizer PBSM added, the notched impact strength reaches 15.4 kJ / m 2 , which is increased by nearly 3 times. Thus, it can be seen that the addition of the antibacterial compatibilizer can effectively improve the toughness of the composite, and at the same time reflect that the compatibility of the two phases has been effectively improved.

[0088] Antibacterial property test of the composite:

[0089] The composites prepared in Example 8 and Replacement Example 2 (PLA / PBAT / PBSM, PLA / PBAT / POSM, PLA / PBAT / PDSM), with the addition amount of the antibacterial compatibilizer in the composite being 3 phr, are used to conduct a control experiment with PLA / PBAT and the blank example according to the following experimental method, and their antibacterial properties are detected, as Figure 9 shown.

[0090] Preparation of PDA medium: Peel 200 g of potatoes, cut them into pieces and crush them, add 1000 mL of water and boil for 30 min, filter with gauze, then add 10 g of glucose and 20 g of agar, fully dissolve and filter with gauze while it is hot into a beaker (already sterilized), seal it with plastic wrap, put it in the refrigerator, and cool it rapidly for standby.

[0091] Cut the PLA / PBAT, PLA / PBAT / PBSM, PLA / PBAT / POSM, and PLA / PBAT / PDSM composite films into discs with a diameter of 30 mm, fix them in a petri dish (and set a blank control), stack them in an electrothermal drying oven, and sterilize them at 121 °C for 20 min. After sterilization, take them out and cool them to room temperature, then place them in a constant temperature incubator at a temperature of (23 ± 1) °C and a relative humidity of 66 - 72%. Observe them after 24 h and 48 h respectively, record the changes, and take photos.

[0092] Result analysis:

[0093] As Figure 9 shown, in different antibacterial petri dishes, it can be found that after 24 h, bacteria began to grow on the petri dishes (blank and PLA / PBAT), while the antibacterial zones of the composite materials added with PBSM and POSM were not obvious. After 48 h, the composite material added with PDSM had an obvious antibacterial zone with a diameter of about 10 mm. This is due to the synergistic effect of imidazole cations and long-chain alkyl groups. The phospholipids of the bacterial cell membrane will be electrostatically attracted by the quaternary ammonium salt, and correspondingly, the long alkyl chain will rupture the phospholipid bilayer, causing the leakage of the bacterial cytoplasmic fluid and thus killing the bacteria. Generally, when the diameter of the antibacterial zone reaches 6 mm, it can indicate that the material has antibacterial function.

[0094] In summary, it can be seen that the PLA / PBAT / antibacterial compatibilizer composite material prepared by the present invention has antibacterial function and can be used to prepare antibacterial materials.

[0095] Summary:

[0096] The present invention prepared quaternary ammonium salt polymers with three alkyl chain lengths, and obtained the PLA / PBAT / antibacterial compatibilizer composite material by melt blending with PLA / PBAT. According to the mechanical property tests, we can find that the addition of the antibacterial compatibilizer effectively changed the compatibility of the composite material, improving the elongation at break and the notched impact strength; at the same time, it also improved the antibacterial property of the composite material. The antibacterial zone of the composite material added with 3 phr of PDSM could reach 10 mm within 48 h.

Claims

1. A preparation method of a quaternary ammonium salt copolymer compatibilized PLA-PBAT antibacterial composite material, characterized in that, It includes the following steps: (1) Prepare compatibilizing copolymer PSM React sodium 4-styrenesulfonate with maleic anhydride in the presence of AIBN and DMF under N2 protection to prepare compatibilizing copolymer PSM; (2) Prepare antibacterial compatibilizer Stir the prepared compatibilizing polymer PSM with quaternary ammonium salt ionic liquid and DMF at room temperature until fine particles precipitate, then centrifuge to remove the precipitated solid to obtain a polymer containing quaternary ammonium salt, namely the antibacterial compatibilizer; In step (2), the quaternary ammonium ionic liquid is any one of imidazolium ionic liquid [C4MIM]Br, imidazolium ionic liquid [C8MIM]Br, and imidazolium ionic liquid 12 [C MIM]Br; (3) Prepare PLA-PBAT antibacterial composite material Vacuum dry the PLA and PBAT masterbatches before use, then blend the antibacterial compatibilizer prepared in step (2) with PLA and PBAT particles, pelletize after blending to obtain the PLA-PBAT antibacterial composite material.

2. The preparation method of a quaternary ammonium salt copolymer compatibilized PLA-PBAT antibacterial composite material according to claim 1, characterized in that: In step (1), under N2 protection, the reaction temperature is 70 - 90 °C and the reaction time is 24 - 72 h.

3. The preparation method of a quaternary ammonium salt copolymer compatibilized PLA-PBAT antibacterial composite material according to claim 2, characterized in that: In step (1), the reaction temperature is 80 °C and the reaction time is 72 h.

4. The preparation method of a quaternary ammonium salt copolymer compatibilized PLA-PBAT antibacterial composite material according to claim 1, characterized in that: The imidazolium ionic liquid [C4MIM]Br is prepared by the following method: Stir 1-methylimidazole, 1-bromobutane and methanol until completely dissolved, then stir and react at room temperature. After the reaction, wash and filter by suction to obtain the imidazolium ionic liquid [C4MIM]Br.

5. The preparation method of a quaternary ammonium salt copolymer-compatibilized PLA-PBAT antibacterial composite material according to claim 1, characterized in that: The imidazolium ionic liquid [C8MIM]Br is prepared by the following method: Stir 1-methylimidazole, 1-bromooctane and methanol until completely dissolved, then stir and react at room temperature. After the reaction, wash and filter by suction to obtain the imidazolium ionic liquid [C8MIM]Br.

6. The preparation method of a quaternary ammonium salt copolymer compatibilized PLA-PBAT antibacterial composite material according to claim 1, characterized in that: Imidazolium ionic liquid monomer [C 12 MIM]Br was prepared by the following method: 1-methylimidazole, 1-bromododecane and methanol were stirred until completely dissolved, and then stirred at room temperature for reaction. After the reaction was completed, it was washed and filtered by suction to obtain imidazolium ionic liquid [C 12 MIM]Br.

7. The preparation method of a quaternary ammonium salt copolymer compatibilized PLA-PBAT antibacterial composite material according to claim 1, characterized in that: In step (3), based on the PLA and PBAT masterbatches, the dosage of the antibacterial compatibilizer is 1 - 5 phr.

8. The preparation method of a quaternary ammonium salt copolymer compatibilized PLA-PBAT antibacterial composite material according to claim 7, characterized in that: In step (3), based on the PLA and PBAT masterbatches, the dosage of the antibacterial compatibilizer is 3 phr.

9. The preparation method of a quaternary ammonium salt copolymer compatibilized PLA-PBAT antibacterial composite material according to claim 1, characterized in that: In step (3), blend the antibacterial compatibilizer with PLA / PBAT particles, the processing temperature is 170 °C and the rotation speed is 50 rpm.

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