Polyionic liquid-based antimicrobial aqueous polyurethane emulsion, and preparation method and application thereof

Abstract

The application relates to a polyionic liquid-based antibacterial waterborne polyurethane emulsion and a preparation method and application thereof. A dihydric alcohol and a diisocyanate are added into a reactor, and then a tertiary amine catalyst or an organic metal compound catalyst is added to obtain a prepolymer; a hydrophilic chain extender is added into the obtained system to continue reaction for a period of time, then a functionalized small molecule ionic liquid monomer is added to continue reaction, and then acetone is used to adjust the viscosity, so that a waterborne polyurethane prepolymer is obtained; after the reaction is completed, the temperature is lowered, a neutralizer is added to react with the hydrophilic chain extender in an equal molar amount, deionized water is added to be emulsified under high-speed shearing, and finally a polyionic liquid-based antibacterial waterborne polyurethane emulsion, namely a polyionic liquid-based waterborne polyurethane emulsion with antibacterial and self-healing functions, is obtained. The polyionic liquid-based antibacterial waterborne polyurethane emulsion has the advantages of simple preparation process, green environmental protection, strong and efficient and durable mildew resistance and antibacterial property, excellent self-healing performance and great application prospect.

Description

Technical Field

[0001] This invention relates to the field of waterborne polyurethane emulsion synthesis, and in particular to a polyionic liquid-based antibacterial waterborne polyurethane emulsion, its preparation method, and its application. Background Technology

[0002] Waterborne polyurethane is a safe, low-VOC, and easy-to-apply environmentally friendly polymer elastic coating. It exhibits good adhesion to polymers, cement, metals, and stone-based materials, and demonstrates good waterproofing, UV aging resistance, chemical corrosion resistance, and flexibility. It is commonly used in textile finishing, leather processing, adhesives, building materials, and medical devices. However, due to the ease with which microorganisms proliferate during application, waterborne polyurethane has poor antibacterial properties, thus limiting its application in fields with high hygiene requirements, such as medical devices, interior building decoration, and textiles.

[0003] Common methods to improve the antibacterial properties of waterborne polyurethane include physical blending or copolymerization modification of antibacterial agents. Physical blending typically involves mixing one or more inorganic antibacterial nanomaterials with a waterborne polyurethane emulsion through stirring or ultrasonication. While simple to operate, this modification method faces the primary problem of nanomaterials easily agglomerating and migrating out, affecting the performance and antibacterial durability of the waterborne polyurethane. Copolymerization modification refers to the prepolymerization of antibacterial agents containing reactive groups such as amino, hydroxyl, thiol, and epoxy groups with isocyanate groups, introducing antibacterial groups into the polyurethane molecular chain through chemical bonding to achieve its antibacterial function. Waterborne polyurethane prepared by this method has good antibacterial effect and high antibacterial durability, and this modification method is the future development direction for antibacterial waterborne polyurethane emulsions.

[0004] Polyionic liquids are a class of ionic polymers whose structural units contain ionic liquid structures. They possess both the functionalities of ionic liquids and the excellent mechanical properties of polymers. The cationic groups of polyionic liquids generate electrostatic interactions with the negatively charged bacterial surfaces and, through the hydrophobic interactions of their hydrophobic segments, disturb the bacterial cell membrane, thus exhibiting antibacterial properties. They are less prone to drug resistance, and most cations possess highly efficient, broad-spectrum antibacterial activity, excellent metabolic stability, and low toxicity. This makes them ideal for preparing highly efficient, low-toxicity antibacterial materials that are less likely to induce drug resistance, making them a research hotspot in the field of antibacterial research.

[0005] Chinese patent CN 115340814A discloses the preparation and application of a cationic polyurethane antibacterial coating. Using phenylimidazolium, chloroethylamine hydrochloride, and diethanolamine-dichlorotriazine as reactants, an imidazole cationic aromatic diol polyurethane chain extender, diethanolamine-di(phenylimidazolium salt amino)triazine compound, is synthesized and participates in the chain extension reaction of polyurethane. The resulting polyurethane hard segments contain rigid aromatic and triazine ring structures, improving the overall thermal stability and mechanical properties of the polyurethane. Simultaneously, it introduces abundant imidazole cationic antibacterial structures, endowing the waterborne polyurethane coating with excellent antibacterial properties. However, the waterborne polyurethane coating in this patent does not possess self-healing capabilities. Summary of the Invention

[0006] The purpose of this invention is to provide a polyionic liquid-based antibacterial aqueous polyurethane emulsion, its preparation method, and its application.

[0007] Based on the current demand for antibacterial materials and the concept of green chemistry, this invention uses diols, diisocyanates, and hydrophilic chain extenders as main raw materials to obtain isocyanate-terminated aqueous polyurethane prepolymers. Subsequently, the isocyanate-terminated prepolymers are copolymerized with functionalized small-molecule ionic liquid monomers. After neutralization and emulsification, a polyionic liquid-based aqueous polyurethane emulsion is obtained. This aqueous emulsion is not only low in toxicity and environmentally friendly, but also possesses excellent antibacterial and antifungal properties. Furthermore, the complex electrostatic synergistic effects between the anions and cations in the ionic liquid structural units of the aqueous polyurethane and the cations in the hydrophilic chain extender, as well as the hydrogen bonding between the polyurethane backbone structures, create physical entanglement between the molecular chains. The presence of soft segments in the polyurethane also provides mobility to the molecular chains, thus endowing the polyurethane emulsion with self-healing capabilities after film formation.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] This invention first provides a method for preparing a polyionic liquid-based antibacterial aqueous polyurethane emulsion, the specific steps of which are as follows:

[0010] Step 1: Add the diol and diisocyanate to the reactor, and then add a tertiary amine catalyst or an organometallic compound catalyst to react and obtain the prepolymer;

[0011] Step 2: Add a hydrophilic chain extender to the system obtained in Step 1 and continue the reaction for a period of time. Then add a functionalized small molecule ionic liquid monomer and continue the reaction. At the same time, adjust the viscosity with acetone to obtain an aqueous polyurethane prepolymer.

[0012] Step 3: After the reaction in Step 2 is completed, cool down, add a neutralizing agent in equimolar amounts to the hydrophilic chain extender, add deionized water for high-speed shear emulsification, and obtain a polyionic liquid-based antibacterial waterborne polyurethane emulsion, i.e., a polyionic liquid-based waterborne polyurethane emulsion with antibacterial and self-healing functions.

[0013] In one embodiment of the present invention, the diol in step 1 is selected from polycaprolactone diol, poly(1,4-butanediol adipate), polytetrahydrofuran ether diol, or polypropylene oxide diol (number average molecular weight M). n One or more of the diisocyanates (between 1000 and 2000); the diisocyanate is selected from one or more of isophorone diisocyanate, phenyl dimethylene diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate.

[0014] In one embodiment of the present invention, the tertiary amine catalyst in step 1 is selected from one or more of N,N-dimethylcyclohexylamine, bis(2-dimethylaminoethyl) ether or triethanolamine;

[0015] In one embodiment of the present invention, the organometallic compound catalyst in step 1 is selected from one or more of dibutyltin dicarboxylate, zinc isooctanoate, dibutyltin diacetate, or bismuth neodecanoate.

[0016] In one embodiment of the present invention, in step 2, the cation of the functionalized small molecule ionic liquid is selected from one or a mixture of several imidazole cations and quaternary ammonium cations.

[0017] The structural formula of the imidazole cation is shown below:

[0018]

[0019] The structures of quaternary ammonium cations are shown below:

[0020]

[0021] In the above structural formula, n represents the number of connections C, which is a positive integer and can be selected from 2 to 18.

[0022] In the above structural formulas, R represents the terminal active group, which is mainly one or more of hydroxyl (-OH), amino (-NH2) or thiol (-SH).

[0023] In one embodiment of the present invention, in step 2, the anion of the functionalized small molecule ionic liquid is selected from one or a mixture of several of chloride ions, bromide ions, iodide ions, tetrafluoroborate ions, hexafluorophosphate ions, trifluoromethanesulfonate ions, or bis(trifluoromethanesulfonyl)imide ions.

[0024] In one embodiment of the present invention, in step 2, the hydrophilic chain extender is selected from one or more of methyl diethanolamine, ethyl diethanolamine, isopropyl diethanolamine, n-butyl diethanolamine or tert-butyl diethanolamine.

[0025] In one embodiment of the present invention, in step 3, the neutralizing agent is selected from one or more of glacial acetic acid, hydrochloric acid, lactic acid, sulfuric acid, or phosphoric acid.

[0026] In one embodiment of the present invention, the reaction conditions for step 1 are as follows: the reaction is carried out in a nitrogen atmosphere, the molar ratio of diol to diisocyanate is 1:2 to 6, the amount of catalyst is 0.01 to 0.1% of the mass of the prepolymer, the reaction temperature is 50 to 100°C, the reaction time is 1 to 5 hours, and the obtained prepolymer is an isocyanate-terminated aqueous polyurethane prepolymer.

[0027] In one embodiment of the present invention, the reaction conditions for step 2 are as follows: the reaction is carried out in a nitrogen atmosphere, the proportion of hydrophilic chain extender is 5-10% of the total mass of the prepolymer obtained in step 1, the mass ratio of functionalized small molecule ionic liquid is 0.5-10% of the total mass of the prepolymer obtained in step 1, the reaction temperature is 50-100°C, the reaction time is 1-5 hours, and acetone is added to dilute the system to a solid content of 40-80%. The obtained waterborne polyurethane prepolymer is the polyionic liquid antibacterial waterborne polyurethane precursor.

[0028] In one embodiment of the present invention, the reaction conditions for step 3 are as follows: the reaction temperature is 20-60°C, the mass ratio of added deionized water is 100-500% of the mass of the waterborne polyurethane prepolymer obtained in step 2, the stirring rate is about 500-2000 rad / s, and the stirring time is 10-30 min, thereby obtaining a polyionic liquid-based antibacterial waterborne polyurethane emulsion.

[0029] The present invention also provides a polyionic liquid-based antibacterial aqueous polyurethane emulsion prepared based on the above preparation method.

[0030] The present invention also provides the application of the polyionic liquid-based antibacterial aqueous polyurethane emulsion prepared by the above preparation method, wherein the polyionic liquid-based antibacterial aqueous polyurethane emulsion is used for: preparing antibacterial membrane materials, antibacterial finishing of fabrics, leather processing, preparing adhesives, preparing building materials, and preparing medical devices.

[0031] The interaction between ionic groups contributes to the self-healing properties of materials, significantly extending their service life and scratch resistance, aligning with the development trend of green chemistry. Therefore, this invention introduces ionic liquids into the waterborne polyurethane chain structure through chemical bonding, obtaining a polyionic liquid-based antibacterial waterborne polyurethane emulsion, which will have broad application prospects in fields such as architectural coatings and medical devices.

[0032] This invention first generates an aqueous polyurethane emulsion prepolymer from a diol and a diisocyanate monomer. Then, a functionalized small-molecule ionic liquid is introduced as a modifying monomer into the cationic aqueous polyurethane chain segment via chemical bonding. Finally, the emulsion is formed through neutralization and high-speed shear emulsification. The electrostatic interactions between the anions and cations in the ionic liquid structural unit and the hydrogen bond network within the polyurethane chain segment endow this polyionic liquid-based aqueous polyurethane emulsion with excellent antifungal, antibacterial, and self-healing properties.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] (1) The polyionic liquid antibacterial waterborne polyurethane prepared by the present invention uses ionic liquid as a functional monomer, realizing the functional application of ionic liquid;

[0035] (2) The polyionic liquid-based antibacterial waterborne polyurethane prepared by this invention has better structural controllability. When the types and ratios of ionic liquid anions / cations are changed, the mechanical properties, thermodynamic properties, hydrophilicity / hydrophobicity, self-healing properties, and antibacterial properties of the polyionic liquid-based antibacterial waterborne polyurethane can be controlled.

[0036] (3) The polyionic liquid-based antibacterial waterborne polyurethane prepared by this invention uses water as a solvent, eliminating highly volatile organic solvents, achieving low VOC emissions, being green and environmentally friendly, conforming to the concept of sustainable development, and having value for promotion and application.

[0037] (4) The present invention introduces ionic liquid monomers containing imidazole groups or quaternary ammonium salts with hydroxyl, amino, or thiol end-capped groups into the polyurethane chain. On the one hand, this can effectively inhibit the growth of bacteria and molds, and on the other hand, the resulting coating has abundant ionic and hydrogen bonds, giving the waterborne polyurethane coating excellent self-healing properties. The ionic liquid structure introduced in this application is significantly different from the structure disclosed in patent CN 115340814A, and the waterborne polyurethane coating in this application has superior self-healing properties compared to the coating described in patent CN 115340814A. Attached Figure Description

[0038] Figure 1 The antibacterial properties of the polyionic liquid-based antibacterial waterborne polyurethane after film formation in Example 1 are shown in (a), (c), and (e), respectively, representing the control groups for Escherichia coli, Staphylococcus aureus, and Acinetobacter niger, while (b), (d), and (f) represent the experimental groups for the corresponding bacterial species in Example 1.

[0039] Figure 2 The self-healing properties of the polyionic liquid-based antibacterial aqueous polyurethane film prepared in Example 1.

[0040] Figure 3The infrared absorption spectra of the polyionic liquid-based antibacterial waterborne polyurethane prepared in Example 1 and the waterborne polyurethane prepared in Example 2 are shown.

[0041] Figure 4 The image shows the hydrogen nuclear magnetic resonance spectrum of the polyionic liquid-based antibacterial waterborne polyurethane in Example 3. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make some non-essential improvements and adjustments based on the above description of the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0043] Example 1

[0044] This embodiment provides a method for preparing a polyionic liquid-based antibacterial aqueous polyurethane emulsion, the steps of which are as follows:

[0045] (1) Add 6.66g of isophorone diisocyanate, 12g of dehydrated poly(1,4-butanediol adipate) (molecular weight 2000) and 0.02g of dibutyltin dilaurate to a three-necked flask equipped with a mechanical stirrer, purge with nitrogen gas, and place the container in an oil bath at a constant temperature of 80°C for 2 hours to obtain a prepolymer with isocyanate end-capped.

[0046] (2) Adjust the reaction temperature to 75℃ and add 2.13g N-methyldiethanolamine and 15mL acetone to the reaction system. After 30min, add 0.77g 1,3-dihydroxyethylimidazolium bromide and 15mL acetone and react for 2h.

[0047] (3) Cool the reaction system to 50°C and add 1.11g of glacial acetic acid for ionization for 15min.

[0048] (4) Increase the mechanical stirring speed of the system to 1300 rad / s, and add 60 mL of deionized water to disperse and emulsify to form an aqueous polyurethane emulsion.

[0049] Example 2

[0050] This embodiment provides a method for preparing an aqueous polyurethane emulsion, the steps of which are as follows:

[0051] (1) Add 6.66g of isophorone diisocyanate, 12g of dehydrated poly(1,4-butanediol adipate) (molecular weight 2000) and 0.02g of dibutyltin dilaurate to a three-necked flask equipped with a mechanical stirrer, purge with nitrogen gas, and place the container in an oil bath at a constant temperature of 80°C for 2 hours to obtain a prepolymer with isocyanate end-capped.

[0052] (2) Adjust the reaction temperature to 75℃ and add 2.13g N-methyldiethanolamine and 15mL acetone to the reaction system. After 30min, add 0.5g 1,4-butanediol and 15mL acetone and react for 2h.

[0053] (3) Cool the reaction system to 50°C and add 1.11g of glacial acetic acid for ionization for 15min.

[0054] (4) Increase the mechanical stirring speed of the system to 1300 rad / s, and add 60 mL of deionized water to disperse and emulsify to form an aqueous polyurethane emulsion.

[0055] Example 3

[0056] This embodiment provides a method for preparing a polyionic liquid-based antibacterial aqueous polyurethane emulsion, the steps of which are as follows:

[0057] (1) Add 7g of diphenylmethane diisocyanate, 6g of dehydrated polytetrahydrofuran ether diol (molecular weight 1000) and 0.05g of dibutyltin dilaurate to a three-necked flask equipped with a mechanical stirrer, introduce nitrogen gas, and place the container in an oil bath at a constant temperature of 80℃ for 2h to obtain a prepolymer with isocyanate end-capping.

[0058] (2) Adjust the reaction temperature to 75℃ and add 1.61g isopropyl diethanolamine and 5mL acetone to the reaction system. After 1h, add 1.80g 1,3-diaminoimidazolium hexafluorophosphate and 5mL acetone and react for 2h.

[0059] (3) Cool the reaction system to 50°C and add 0.83g of glacial acetic acid for ionization for 15min.

[0060] (4) Increase the mechanical stirring speed of the system to 1300 rad / s, and add 60 mL of deionized water to disperse and emulsify to form an aqueous polyurethane emulsion.

[0061] Example 4

[0062] This embodiment provides a method for preparing a polyionic liquid-based antibacterial aqueous polyurethane emulsion, the steps of which are as follows:

[0063] (1) Add 6.66g of isophorone diisocyanate, 12g of dehydrated polytetrahydrofuran ether diol (molecular weight 2000) and 0.1g of dibutyltin dilaurate to a three-necked flask equipped with a mechanical stirrer, purge with nitrogen gas, and place the container in an oil bath at a constant temperature of 80℃ for 1h to obtain a prepolymer with isocyanate end-capped.

[0064] (2) Adjust the reaction temperature to 75℃, add 2g of isopropyl diethanolamine and 5mL of acetone to the reaction system, and after 30min, add 1.95g of dimethyl dihydroxyethylammonium chloride and 5mL of acetone and react for 2h.

[0065] (3) Cool the reaction system to 50°C and add 0.83g of hydrochloric acid for ionization for 15min.

[0066] (4) Increase the mechanical stirring speed of the system to 1300 rad / s, and add 60 mL of deionized water to disperse and emulsify to form an aqueous polyurethane emulsion.

[0067] Example 5

[0068] This embodiment provides a method for preparing a polyionic liquid-based antibacterial aqueous polyurethane emulsion, the steps of which are as follows:

[0069] (1) Add 12g of isophorone diisocyanate, 12g of dehydrated polycaprolactone diol (molecular weight 2000) and 0.05g of dibutyltin dilaurate to a three-necked flask equipped with a mechanical stirrer, introduce nitrogen gas, and place the container in an oil bath at a constant temperature of 100℃ for 2h to obtain a prepolymer with isocyanate end-capping.

[0070] (2) Adjust the reaction temperature to 75℃, add 2g N-methyldiethanolamine and 5ml acetone to the reaction system, and after 30min, add 1.31g dimethyldihydroxyethylammonium hexafluorophosphate and 5ml acetone and react for 2h.

[0071] (3) Cool the reaction system to 50°C and add 0.83g of glacial acetic acid for ionization for 15min.

[0072] (4) Increase the mechanical stirring speed of the system to 1300 rad / s, add 60 ml of deionized water to disperse and emulsify to form an aqueous polyurethane emulsion.

[0073] Example 6

[0074] This embodiment provides a method for preparing a polyionic liquid-based antibacterial aqueous polyurethane emulsion, the steps of which are as follows:

[0075] (1) Add 12g of isophorone diisocyanate, 12g of dehydrated poly(1,4-butanediol adipate) (molecular weight 2000) and 0.05g of dibutyltin dilaurate to a three-necked flask equipped with a mechanical stirrer, purge with nitrogen gas, and place the container in an oil bath at a constant temperature of 80°C for 2 hours to obtain a prepolymer with isocyanate end-capped.

[0076] (2) Adjust the reaction temperature to 75℃, add 2g N-ethyldiethanolamine and 5mL acetone to the reaction system, and after 30min, add 1.65g 1,3-dimercaptoimidazolium bromide and 5mL acetone and react for 2h.

[0077] (3) Cool the reaction system to 50°C and add 0.83g of glacial acetic acid for ionization for 15min.

[0078] (4) Increase the mechanical stirring speed of the system to 1300 rad / s, add 30 ml of deionized water to disperse and emulsify to form an aqueous polyurethane emulsion.

[0079] Example 7

[0080] This embodiment provides a method for preparing a polyionic liquid-based antibacterial aqueous polyurethane emulsion, the steps of which are as follows:

[0081] (1) Add 12g of toluene diisocyanate, 12g of dehydrated polycaprolactone diol (molecular weight 2000) and 0.05g of dibutyltin dilaurate to a three-necked flask equipped with a mechanical stirrer, purge with nitrogen gas, and place the container in an oil bath at a constant temperature of 80℃ for 2h to obtain a prepolymer with isocyanate end-capped.

[0082] (2) Adjust the reaction temperature to 75℃, add 2g N-methyldiethanolamine and 5mL acetone to the reaction system, and after 30min, add 1.31g 1,3-dihydroxyethylimidazolium tetrafluoroborate and 5mL acetone and react for 2h.

[0083] (3) Cool the reaction system to 50°C and add 0.83g of glacial acetic acid for ionization for 30min.

[0084] (4) Increase the mechanical stirring speed of the system to 1300 rad / s, and add 60 mL of deionized water to disperse and emulsify to form an aqueous polyurethane emulsion.

[0085] Figure 1 Antibacterial properties were tested on the polyionic liquid-based antibacterial aqueous polyurethane emulsion after film formation.

[0086] The specific method for antibacterial testing is as follows: 100 μL of bacterial suspension was dropped onto sterilized base paper (blank control group) and base paper coated with antibacterial aqueous polyurethane emulsion (experimental group), and incubated at 37°C for 4 hours. Then, 10 μL of bacterial suspension from each of the blank control group and experimental group was dropped onto LB agar plates for even coverage. After incubation at 37°C for another 24 hours, the surviving colonies were counted. Three parallel colony tests were performed for each sample, the average value was taken, and the antibacterial rate was calculated using the following formula:

[0087] A = (N0 - N1) / N0 × 100%

[0088] Where A: Antibacterial rate (%);

[0089] N0: Colony count in the blank control group agar plate;

[0090] N1: The number of colonies in the agar plate in the experimental group.

[0091] Mold resistance was tested according to the national standard GB / T 1741-2020 "Test Method for Mold Resistance of Paint Films".

[0092] In the figures, (a), (c), and (e) represent the blank control groups for *Escherichia coli*, *Staphylococcus aureus*, and *Nephroticula nigra*, respectively; and (b), (d), and (f) represent the experimental groups for *Escherichia coli*, *Staphylococcus aureus*, and *Nephroticula nigra* after film formation using the polyionic liquid-based antibacterial waterborne polyurethane emulsion of Example 1, respectively. The experimental results show that the bactericidal rate against *Escherichia coli* and *Staphylococcus aureus* after film formation using the polyionic liquid-based antibacterial waterborne polyurethane emulsion of Example 1 is 99.9%.

[0093] Figure 2 To demonstrate the self-healing properties of the polyionic liquid-based antibacterial waterborne polyurethane film in Example 1, the waterborne polyurethane film was scratched with a knife and then placed in a 60°C constant temperature oven for 24 hours. The scratches clearly disappeared and healed, indicating that the addition of imidazole-based ionic liquid monomers gives the waterborne polyurethane coating good self-healing properties. Figure 3 The infrared absorption spectra of the waterborne polyurethane prepared in Example 1 and Example 2 are shown, with wavenumbers around 1400 cm⁻¹. -1 and 1137cm -1 The absorption peak is the infrared absorption peak of the imidazole ring, 910 cm⁻¹. -1 The infrared absorption peak at this point represents the bromide anion, indicating that the imidazole cation has been successfully introduced into the molecular chain segment of the polyurethane. Figure 4 The image shows the 1H NMR spectrum of the polyionic liquid-based antibacterial waterborne polyurethane in Example 3. The f1 values ​​at 9.1 ppm and 7.8 ppm represent proton shifts on the imidazole ring, demonstrating that the imidazole cation was successfully introduced into the molecular chain of the polyurethane.

[0094] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a polyionic liquid-based antibacterial aqueous polyurethane emulsion, characterized in that, The specific steps are as follows: Step 1: Add the diol and diisocyanate to the reactor, and then add a tertiary amine catalyst or an organometallic compound catalyst to react and obtain the prepolymer; Step 2: Add a hydrophilic chain extender to the system obtained in Step 1 and continue the reaction for a period of time. Then add a functionalized small molecule ionic liquid monomer and continue the reaction. At the same time, adjust the viscosity with acetone to obtain an aqueous polyurethane prepolymer. Step 3: After the reaction in Step 2 is completed, cool down, add a neutralizing agent in equimolar amounts to the hydrophilic chain extender, add deionized water for high-speed shear emulsification, and obtain a polyionic liquid-based antibacterial waterborne polyurethane emulsion, i.e., a polyionic liquid-based waterborne polyurethane emulsion with antibacterial and self-healing functions. In step 2, the functionalized small molecule ionic liquid is selected from 1,3-dihydroxyethylimidazolium bromide; The hydrophilic chain extender is selected from one or more of methyl diethanolamine, ethyl diethanolamine, isopropyl diethanolamine, n-butyl diethanolamine or tert-butyl diethanolamine; In step 3, the neutralizing agent is selected from one or more of glacial acetic acid, hydrochloric acid, lactic acid, sulfuric acid, or phosphoric acid; The electrostatic synergy between the anions and cations in the ionic liquid structural units of waterborne polyurethane and the cations in the hydrophilic chain extender, as well as the hydrogen bonding between the polyurethane main chain structures, enables the molecular chains to form physical entanglements. Furthermore, the presence of polyurethane soft segments provides the molecular chains with mobility, thus endowing the polyurethane emulsion with self-healing ability after film formation. The ionic liquid is introduced into the waterborne polyurethane segment structure through chemical bonding.

2. The method for preparing a polyionic liquid-based antibacterial aqueous polyurethane emulsion according to claim 1, characterized in that, The diol mentioned in step 1 is selected from one or more of polycaprolactone diol, poly(1,4-butanediol adipate), polytetrahydrofuran ether diol, or polypropylene oxide diol; the diisocyanate is selected from one or more of isophorone diisocyanate, phenyl diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate.

3. The method for preparing a polyionic liquid-based antibacterial aqueous polyurethane emulsion according to claim 1, characterized in that, The tertiary amine catalyst mentioned in step 1 is selected from one or more of N,N-dimethylcyclohexylamine, bis(2-dimethylaminoethyl) ether, or triethanolamine; The organometallic catalyst mentioned in step 1 is selected from one or more of dibutyltin dilaurate, zinc isooctanoate, dibutyltin diacetate, or bismuth neodecanoate.

4. The method for preparing a polyionic liquid-based antibacterial aqueous polyurethane emulsion according to claim 1, characterized in that, The reaction conditions for step 1 are as follows: the reaction is carried out in a nitrogen atmosphere, the molar ratio of diol to diisocyanate is 1:2~6, the amount of catalyst is 0.01~0.1% of the mass of the prepolymer, the reaction temperature is 50~100℃, the reaction time is 1~5 hours, and the obtained prepolymer is an isocyanate-terminated aqueous polyurethane prepolymer.

5. The method for preparing a polyionic liquid-based antibacterial aqueous polyurethane emulsion according to claim 1, characterized in that, The reaction conditions for step 2 are as follows: the reaction is carried out in a nitrogen atmosphere, the proportion of hydrophilic chain extender is 5-10% of the total mass of the prepolymer obtained in step 1, the mass ratio of functionalized small molecule ionic liquid is 0.5-10% of the total mass of the prepolymer obtained in step 1, the reaction temperature is 50-100℃, the reaction time is 1-5h, and acetone is added to dilute the system to a solid content of 40-80%. The resulting waterborne polyurethane prepolymer is the polyionic liquid antibacterial waterborne polyurethane precursor.

6. The method for preparing a polyionic liquid-based antibacterial aqueous polyurethane emulsion according to claim 1, characterized in that, The reaction conditions for step 3 are as follows: the reaction temperature is 20~60℃, the mass ratio of deionized water added is 100~500% of the mass of the waterborne polyurethane prepolymer obtained in step 2, the stirring rate is 500~2000 rad / s, and the stirring time is 10~30 min, to obtain a polyionic liquid-based antibacterial waterborne polyurethane emulsion.

7. A polyionic liquid-based antibacterial aqueous polyurethane emulsion prepared by any one of the preparation methods described in claims 1-6.

8. The application of the polyionic liquid-based antibacterial aqueous polyurethane emulsion according to claim 7, characterized in that, The polyionic liquid-based antibacterial aqueous polyurethane emulsion is used for: preparing antibacterial membrane materials, antibacterial finishing of fabrics, leather processing, preparing adhesives, preparing building materials, and preparing medical devices.

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