Preparation method and application of coated and enhanced nano silver powder

Abstract

The present invention provides a preparation method and application of coated and enhanced nano silver powder. S1: Using silver nitrate as a silver source and polyethyleneimine as a reducing agent to prepare nano silver; S2: Using aniline and ammonium persulfate to coat and modify the nano silver under acidic conditions; S3: Using chloroacetic acid to modify the nano silver coated with polyaniline to obtain chloroacetic acid-modified polyaniline-coated nano silver; S4: Preparing a modified graphene oxide dispersion; S5: Partially reducing graphene oxide; S6: Using the partially reduced graphene oxide to load the chloroacetic acid-modified polyaniline-coated nano silver. The present invention effectively improves the dispersibility and stability of nano silver particles through the combination of polyaniline coating and reduced graphene oxide. The oxidized state of polyaniline promotes the release of silver ions through electron transfer, thereby enhancing the antibacterial effect; while the partially reduced graphene oxide synergistically accelerates the release of silver ions, further improving the antibacterial performance.

Description

Technical Field

[0001] The invention relates to the field of nano silver antibacterial coatings, and in particular to a preparation method and application of coated enhanced nano silver powder. Background Art

[0002] Nanosilver (AgNPs) is widely used in the fields of medical treatment, hygiene, food packaging, etc. due to its excellent antibacterial properties. Nanosilver particles have a large specific surface area and surface effect, and can release silver ions to interact with bacterial cell walls, thereby inhibiting the growth and reproduction of bacteria. The antibacterial mechanism of silver ions is mainly to destroy the structure of bacterial cell walls, interfere with their metabolic processes and DNA replication, and ultimately lead to bacterial death. Therefore, nanosilver coatings play an important role in preventing the spread of bacteria in places such as hospitals and clinics.

[0003] Hospitals, operating rooms, emergency rooms and other medical environments have very high requirements for coatings. In addition to having antibacterial functions to prevent hospital infections, coatings also need to meet other performance requirements. Especially on the surface of medical equipment, such as diagnostic equipment, monitoring instruments, infusion pumps, etc., these devices are not only often exposed to high-frequency cleaning and disinfection environments, but are also susceptible to static electricity accumulation. Static electricity may interfere with the normal operation of precision equipment and even cause equipment failure. Therefore, the coating also needs to have antistatic properties to ensure the stability and safety of the equipment.

[0004] In addition, the surface of medical equipment often needs to withstand frequent wiping, disinfection and long-term use, so the coating must also have good wear resistance to avoid loss of function due to friction during cleaning and use.

[0005] Although nanosilver coatings have excellent antibacterial performance, they still face certain technical difficulties in practical applications. First, nanosilver particles are prone to agglomeration, resulting in uneven distribution of silver particles in the coating, which in turn affects the stability and durability of its antibacterial effect. In addition, the uneven release of silver ions may cause the antibacterial performance to decline over time. Secondly, existing nanosilver coatings often cannot fully meet the strict requirements of the medical environment in terms of antistatic and wear resistance. For example, static electricity accumulation may cause electrical interference to precision medical equipment, and insufficient wear resistance of the coating will cause damage to the surface coating of the equipment, thereby affecting the normal function and service life of the equipment.

[0006] Therefore, developing a nanosilver coating that can ensure long-lasting antibacterial effect while also having excellent antistatic and wear resistance has become a technical problem that needs to be solved urgently in the medical environment. Summary of the invention

[0007] In view of the above analysis, the present invention aims to provide a preparation method and application of coated enhanced nano silver powder to solve the problems in the background art.

[0008] The object of the present invention is mainly achieved through the following technical solutions:

[0009] A preparation method of coated enhanced nano silver powder, comprising the following steps:

[0010] S1: Using silver nitrate as a silver source and polyethyleneimine as a reducing agent to prepare nano silver;

[0011] S2: Using aniline and ammonium persulfate to coat and modify the nano silver under acidic conditions to obtain polyaniline-coated nano silver;

[0012] S3: Using chloroacetic acid to modify the polyaniline-coated nano silver to obtain chloroacetic acid-modified polyaniline-coated nano silver;

[0013] S4: Preparing graphene oxide by oxidizing graphite, and then modifying it with polyethyleneimine to obtain a modified graphene oxide dispersion;

[0014] S5: Using sodium hydride to partially reduce the graphene oxide to obtain a reduced graphene oxide aqueous dispersion;

[0015] S6: Using reduced graphene oxide to load the chloroacetic acid-modified polyaniline-coated nano silver to obtain the coated enhanced nano silver powder.

[0016] In one or more embodiments, the specific process of step S1 is as follows:

[0017] Calculated by weight components, 5-8 parts of silver nitrate are uniformly dispersed in 100 parts of deionized water to obtain a first reaction solution; 25-40 parts of polyethyleneimine are uniformly dispersed in 250 parts of deionized water to obtain a second reaction solution; the first reaction solution and the second reaction solution are mixed, the pH value is adjusted to 1-2, and the mixture is stirred evenly and fully reacted under an oil bath condition of 80-100 °C to obtain a third reaction solution; the third reaction solution is subjected to suction filtration, washing and drying to obtain nano silver.

[0018] In one or more embodiments, the specific process of step S2 is as follows: Take 1 part of the nano silver and 0.1-0.2 part of sodium dodecyl sulfate, ultrasonically disperse them in deionized water, then add 1.7-3.4 parts of aniline and 4-6 parts of ammonium persulfate, adjust the pH value to 1-2, stir and react at 0-5 °C for 1-2 h, then perform solid-liquid separation, and wash and dry the obtained solid with ethanol to obtain polyaniline-coated nano silver.

[0019] In one or more embodiments, the specific process of step S3 is as follows:

[0020] Take 1 part of polyaniline-coated silver nanoparticles, add 0.5 - 1.5 parts of chloroacetic acid dissolved in deionized water, adjust the pH value of the solution to 1 - 2, and stir for reaction for 3 - 5 h;

[0021] After the reaction is completed, perform suction filtration, washing, and clean with ethanol, and finally dry at 60 - 80 °C to obtain chloroacetic acid-modified polyaniline-coated silver nanoparticles.

[0022] In one or more embodiments, the specific process of step S4 is as follows: uniformly disperse 1 - 2 parts of graphite in 50 parts of concentrated sulfuric acid, add 4 - 10 parts of concentrated nitric acid, stir in an ice-water bath, and slowly heat to room temperature, and continue stirring for reaction for 6 - 12 hours to generate graphene oxide; after the reaction is completed, perform centrifugal washing multiple times to remove residual acidic substances and unreacted impurities, and disperse in 200 parts of deionized water to obtain a graphene oxide aqueous dispersion; then perform ultrasonic treatment, with a frequency of 40 - 80 kHz, a power of 200 - 300 W, and an ultrasonic time of 30 - 40 min to ensure that the graphene oxide is completely dispersed; then, add 2 - 8 parts of polyethyleneimine to the graphene oxide dispersion, and continue stirring for reaction for 2 - 3 h to obtain a modified graphene oxide dispersion.

[0023] In one or more embodiments, the specific process of step S5 is as follows: add 1 - 2 parts of reducing agent sodium hydride to the modified graphene oxide dispersion, and stir for reaction for 2 - 3 h to obtain a reduced graphene aqueous dispersion.

[0024] In one or more embodiments, the specific process of step S6 is as follows: take 1 part of the chloroacetic acid-modified polyaniline-coated silver nanoparticles, add 0.1 - 0.2 parts of sodium dodecyl sulfate, and ultrasonically disperse in 100 parts of deionized water, with an ultrasonic frequency of 40 - 60 kHz and a power of 200 - 400 W to ensure that the silver nanoparticle particles are uniformly dispersed; then mix with the reduced graphene aqueous dispersion to obtain a composite reaction solution; adjust the pH value of the solution to 1 - 1.5, stir for reaction for 1 - 2 h under the condition of 0 - 5 °C, separate the solid and liquid of the reactant, and then wash and dry to obtain reduced graphene-supported silver nanoparticles, that is, the coated enhanced silver nanopowder.

[0025] The present invention provides an application of the coated enhanced silver nanopowder in coatings in a second aspect.

[0026] The present invention provides a silver nanoparticle coating in a third aspect, including: 10 - 15 parts of coated enhanced silver nanopowder, 30 - 40 parts of epoxy resin, 5 - 10 parts of curing agent dicyclohexylamine, 1 - 2 parts of dispersant sodium dodecyl sulfate, 0.5 - 2 parts of plasticizer dibutyl phthalate, and 5 - 10 parts of ethanol.

[0027] The present invention provides a method for a silver nanoparticle coating in a fourth aspect, including the following steps:

[0028] Take 10 - 15 parts of coated enhanced silver nanoparticles, add them to 60 parts of deionized water, and disperse them evenly by ultrasonic wave.

[0029] Take 30 - 40 parts of epoxy resin and place it in a high - shear stirrer for standby.

[0030] Gradually add the coated enhanced silver nanoparticle liquid to the epoxy resin while stirring.

[0031] Add 5 - 10 parts of curing agent dicyclohexylamine and 0.5 - 2 parts of plasticizer dibutyl phthalate to the high - shear stirrer, and continue to stir evenly to ensure that the curing agent is completely distributed in the epoxy resin.

[0032] Finally, add 5 - 10 parts of ethanol to adjust the viscosity of the coating.

[0033] Pour the coating into a mold, place it in an oven, and cure it at 60 - 80 °C for 2 - 4 hours to obtain the nanosilver coating.

[0034] The principle and mechanism of the present invention are as follows:

[0035] The antibacterial property of silver nanoparticles mainly depends on the release of silver ions (Ag + ). Silver ions can destroy the cell wall of bacteria, inhibit DNA synthesis, and interfere with the metabolic process of bacteria, so they have a broad - spectrum antibacterial effect. However, silver nanoparticles are prone to agglomeration, resulting in a reduction in their surface area and a weakening of the antibacterial effect. To solve this problem, the present invention coats silver nanoparticles with polyaniline and composes with partially reduced graphene oxide, effectively improving the dispersibility, stability of silver nanoparticles, and enhancing their antibacterial property.

[0036] As a conductive polymer material, polyaniline (PANI) can effectively prevent the agglomeration and precipitation of silver particles while coating the silver nanoparticles. Polyaniline can not only uniformly coat the silver nanoparticles, protect the silver particles from oxidation, but also enhance the long - term stability of the silver particles.

[0037] The oxidized state of polyaniline has a promoting effect on the release of silver ions. In step S2, ammonium persulfate (APS) reacts with aniline as an oxidant and initiator to oxidize aniline monomers to form oxidized polyaniline (PANI - EB, emeraldine base). In this process, ammonium persulfate converts polyaniline into the oxidized state through an oxidation reaction, which endows polyaniline with the semiconductor property of π - electrons. The oxidized state of polyaniline has a strong electron - accepting ability, and this characteristic can change the electronic environment on the surface of silver nanoparticles. When polyaniline is in the oxidized state, polyaniline promotes the oxidation reaction on the surface of silver nanoparticles through electron transfer, and silver changes from the metallic state to silver ions (Ag +). This oxidation process accelerates the release of silver ions and enhances the antibacterial effect.

[0038] Specifically, the oxidized state of polyaniline provides a pathway for electron transfer, enabling silver ions to be released more rapidly from the surface of silver particles into the solution, thereby enhancing the antibacterial effect of the composite material and the biological activity of silver.

[0039] The synergistic effect of the introduction of partially reduced graphene oxide and silver ion release. The introduction of partially reduced graphene oxide (rGO) in the composite material plays an important role. Graphene oxide itself has abundant oxygen functional groups, which have strong interactions with the surfaces of polyaniline and silver particles, effectively preventing the aggregation and precipitation of silver particles. Partially reduced graphene has good electrical conductivity and can form a continuous conductive network in the composite material, which is beneficial for eliminating static electricity.

[0040] The conductive network of graphene provides an electron transfer channel for polyaniline, promoting the rapid release of silver ions. Since graphene can rapidly migrate electrons, it further accelerates the formation of the oxidized state of polyaniline, thus accelerating the release of silver ions. The presence of graphene not only improves the electrical conductivity of the composite material but also makes the release of silver ions more uniform and persistent, further enhancing the antibacterial effect. Among them, polyethyleneimine, through its amino The interaction with the oxygen functional groups on the surface of graphene oxide not only improves the dispersibility and stability of graphene oxide but also enhances the electrical conductivity of graphene oxide through charge transfer. Graphene oxide itself has strong electron conductivity, and the introduction of polyethyleneimine can optimize the electron transport path, providing better electrical conductivity and antibacterial effect for the composite material.

[0041] As a two-dimensional carbon material, graphene has excellent mechanical properties, especially playing an important role in enhancing the tensile strength, hardness, and toughness of the composite material. In the present invention, partially reduced graphene not only improves the electrical conductivity of the composite material but also significantly enhances the mechanical properties of the coating. The introduction of graphene forms a strong network structure, which can effectively improve the scratch resistance, wear resistance, and compressive resistance of the coating, thereby enhancing the mechanical strength and durability of the coating in actual use.

[0042] Chloroacetic acid can react with the amino groups in polyaniline to introduce carboxylic acid groups (-COOH). This modification increases the polarity of polyaniline, making it more compatible with the epoxy resin matrix. In addition, the carboxylic acid groups introduced on the surface of polyaniline can undergo a ring-opening reaction with epoxy groups during the curing process of epoxy resin to form an ether structure, thereby improving the interfacial adhesion strength and binding force, and enhancing the mechanical properties and chemical stability of the coating.

[0043] The combination of silver nanoparticles, polyaniline, and graphene not only improves the antibacterial effect but also enhances the electrical conductivity, mechanical properties, stability, and durability of the composite material, enabling the composite material to have better long-term applicability under different environmental conditions.

[0044] Compared with the prior art, the present invention has at least the following beneficial effects:

[0045] (1) Through the technology of polyaniline coating and partial reduction of graphene oxide composite, the present invention effectively improves the dispersibility and stability of silver nanoparticles. The oxidized state of polyaniline promotes the release of silver ions through electron transfer, thereby enhancing the antibacterial effect; while the conductivity of partially reduced graphene oxide provides an electron transfer channel, accelerating the release of silver ions and further improving the antibacterial performance. The introduction of graphene not only enhances the electrical conductivity of the coating, effectively reducing the surface resistance of the coating, but also significantly improves the mechanical properties and durability of the coating. The modification of chloroacetic acid improves the compatibility between polyaniline and epoxy resin, further enhancing the overall performance of the composite coating. The synergistic effect of the three makes the composite material show significant advantages in antibacterial properties, electrical conductivity, mechanical properties, durability, and environmental adaptability, and is suitable for applications in various harsh environments.

[0046] (2) The present invention can achieve the stable coating and dispersion of silver nanoparticles at low temperatures and mild chemical conditions. This makes the production process simpler and more environmentally friendly compared to traditional silver nanoparticle synthesis technologies (such as high-temperature and high-pressure reactions, the use of strong reducing agents, etc.).

[0047] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent specification, and some advantages can be made obvious from the specification or understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained through the content specifically pointed out in the specification and the drawings. Description of the Drawings

[0048] The drawings are only for the purpose of showing specific embodiments and are not considered to limit the present invention. Throughout the drawings, the same reference signs represent the same components.

[0049] Figure 1 It is a process flow chart for the preparation of the coated and enhanced silver nanopowder of the present invention. Detailed Embodiments

[0050] The technical solutions of the present invention will be further described below in conjunction with specific embodiments. However, the present invention should not be limited to these embodiments. Unless otherwise stated, they can be replaced by other equivalent or similar-purpose alternative features. Unless otherwise stated, each feature is only an example in a series of equivalent or similar features. The terms used in the present invention generally have the meanings commonly understood by those of ordinary skill in the art, unless otherwise specified. In the following embodiments, unless otherwise stated, the concentration % refers to the mass percentage; the substances used can all be obtained commercially.

[0051] The reagents used in the examples and comparative examples of the present invention are as follows. Those skilled in the art can replace them according to actual needs, which are not used to limit the present invention.

[0052] Epoxy resin E51 was selected and purchased from Shandong Deyuan Epoxy Technology Co., Ltd.

[0053] Aniline was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0054] Silver nitrate was purchased from Tianjin Beifang Tianyi Chemical Reagent Factory.

[0055] Polyethyleneimine was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with an average MW of 250,000.

[0056] Ammonium persulfate was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., electrophoresis grade, ≥98%.

[0057] Figure 1 The preparation process flow of the coated enhanced nano silver powder of the present invention is shown.

[0058] Example 1

[0059] By weight components, 6 parts of silver nitrate were uniformly dispersed in 100 parts of deionized water to obtain a first reaction solution; 30 parts of polyethyleneimine were uniformly dispersed in 250 parts of deionized water to obtain a second reaction solution; the first reaction solution and the second reaction solution were mixed, the pH value was adjusted to 1.5, and the mixture was stirred evenly and reacted fully under the condition of an oil bath at 90 °C to obtain a third reaction solution; the third reaction solution was filtered, washed, and dried to obtain nano silver.

[0060] Take 1 part of the nano silver and 0.1 part of sodium dodecyl sulfate, ultrasonically disperse them in deionized water, then add 1.7 parts of aniline and 4 parts of ammonium persulfate, adjust the pH value to 1, stir and react at 0 °C for 1 h, then carry out solid-liquid separation, and wash the obtained solid twice with ethanol and then vacuum dry to obtain nano silver coated with polyaniline.

[0061] Take 1 part of the nano silver coated with polyaniline, add 0.5 part of chloroacetic acid dissolved in deionized water, adjust the pH value of the solution to 1, and stir and react for 3 h.

[0062] After the reaction is completed, suction filtration and washing are carried out, and it is washed 3 times with ethanol, and finally dried at 60 °C to obtain chloroacetic acid-modified polyaniline-coated silver nanoparticles.

[0063] Disperse 1 part of graphite evenly in 50 parts of concentrated sulfuric acid, add 4 parts of concentrated nitric acid, stir in an ice-water bath, and slowly heat to room temperature, and continue stirring and reacting for 6 hours to generate graphene oxide; after the reaction is completed, perform multiple centrifugal washings to remove residual acidic substances and unreacted impurities, and then disperse in 200 parts of deionized water to obtain a graphene oxide aqueous dispersion; then perform ultrasonic treatment, with a frequency of 40 kHz, a power of 200 W, and an ultrasonic time of 30 min to ensure that the graphene oxide is completely dispersed; then, add 2 parts of polyethyleneimine to the graphene oxide dispersion, and continue stirring and reacting for 2 h to obtain a modified graphene oxide dispersion.

[0064] Add 1 part of the reducing agent sodium hydride to the modified graphene oxide dispersion, stir and react for 2 h, and after the reaction is completed, obtain a reduced graphene aqueous dispersion.

[0065] Take 1 part of the chloroacetic acid-modified polyaniline-coated silver nanoparticles, add 0.1 part of sodium dodecyl sulfate, and ultrasonically disperse in 100 parts of deionized water. Through ultrasonic treatment with a frequency of 40 kHz and a power of 200 W, ensure that the silver nanoparticle particles are evenly dispersed; then mix with the reduced graphene aqueous dispersion; obtain a composite reaction solution; adjust the pH value of the solution to 1, stir and react at 0 °C for 1 h, separate the solid and liquid of the reactants, and then through washing and drying, obtain reduced graphene-supported silver nanoparticles, that is, the coated enhanced silver nanopowder.

[0066] Take 10 parts of the coated enhanced silver nanopowder, add it to 60 parts of deionized water, and ultrasonically disperse it evenly;

[0067] Take 30 parts of epoxy resin and place it in a high-shear stirrer for standby;

[0068] Gradually add the coated enhanced silver nanoparticle liquid and 1 part of the dispersant sodium dodecyl sulfate to the epoxy resin, and stir while adding;

[0069] Add 5 parts of the curing agent dicyclohexylamine and 0.5 part of the plasticizer dibutyl phthalate to the high-shear stirrer, and continue to stir evenly to ensure that the curing agent is completely distributed in the epoxy resin;

[0070] Finally, add 5 parts of ethanol to adjust the viscosity of the coating.

[0071] Pour the coating into a mold, place it in an oven, and cure at 75 °C for 2 hours to obtain the silver nanoparticle coating.

[0072] Example 2

[0073] By weight components, 8 parts of silver nitrate are uniformly dispersed in 100 parts of deionized water to obtain a first reaction solution; 40 parts of polyethyleneimine are uniformly dispersed in 250 parts of deionized water to obtain a second reaction solution; the first reaction solution and the second reaction solution are mixed, the pH value is adjusted to 1, and the mixture is stirred evenly under an oil bath condition of 80 °C to fully react to obtain a third reaction solution; the third reaction solution is subjected to suction filtration, washing and drying to obtain silver nanoparticles.

[0074] Take 1 part of the silver nanoparticles and 0.1 part of sodium dodecyl sulfate, ultrasonically disperse them in deionized water, then add 2 parts of aniline and 6 parts of ammonium persulfate, adjust the pH value to 1, at 0 °C, stir and react for 1 h, then carry out solid-liquid separation, and wash the obtained solid twice with ethanol and then dry it under vacuum to obtain silver nanoparticles coated with polyaniline.

[0075] Take 1 part of the silver nanoparticles coated with polyaniline, add 0.5 part of chloroacetic acid and dissolve it in deionized water, adjust the pH value of the solution to 1, and stir and react for 3 h.

[0076] After the reaction is completed, carry out suction filtration, washing, and wash with ethanol 3 times, and finally dry at 60 °C to obtain chloroacetic acid-modified polyaniline-coated silver nanoparticles.

[0077] Disperse 1 part of graphite evenly in 50 parts of concentrated sulfuric acid, add 4 parts of concentrated nitric acid, stir in an ice-water bath, and slowly heat to room temperature, and continue to stir and react for 8 hours to generate graphene oxide; after the reaction is completed, carry out centrifugal washing multiple times to remove residual acidic substances and unreacted impurities, and then disperse it in 200 parts of deionized water to obtain a graphene oxide aqueous dispersion; then carry out ultrasonic treatment with a frequency of 80 kHz, a power of 300 W, and an ultrasonic time of 40 min to ensure that the graphene oxide is completely dispersed; then, add 8 parts of polyethyleneimine to the graphene oxide dispersion, and continue to stir and react for 3 h to obtain a modified graphene oxide dispersion.

[0078] Add 2 parts of the reducing agent sodium hydride to the modified graphene oxide dispersion, stir and react for 3 h, and after the reaction is completed, obtain a reduced graphene aqueous dispersion.

[0079] Take 1 part of the chloroacetic acid-modified polyaniline-coated silver nanoparticles, add 0.2 part of sodium dodecyl sulfate, ultrasonically disperse them in 100 parts of deionized water, and ensure the uniform dispersion of silver nanoparticle through ultrasonic treatment with a frequency of 60 kHz and a power of 400 W; then mix it with the reduced graphene aqueous dispersion to obtain a composite reaction solution; adjust the pH value of the solution to 1.5, stir and react at 2 °C for 2 h, carry out solid-liquid separation of the reactants, and then through washing and drying, obtain reduced graphene-supported silver nanoparticles, that is, the coated enhanced silver nanopowder.

[0080] Take 15 parts of the coated enhanced silver nanopowder, add it to 60 parts of deionized water, and ultrasonically disperse it evenly.

[0081] Take 30 parts of epoxy resin and place it in a high-shear stirrer for standby;

[0082] Gradually add the coated enhanced nano-silver liquid and 1 part of the dispersant sodium dodecyl sulfate to the epoxy resin, stirring while adding;

[0083] Add 8 parts of the curing agent dicyclohexylamine and 1 part of the plasticizer dibutyl phthalate to the high-shear stirrer, and continue to stir evenly to ensure that the curing agent is completely distributed in the epoxy resin;

[0084] Finally, add 8 parts of ethanol to adjust the viscosity of the coating.

[0085] Pour the coating into a mold, place it in an oven, and cure it at 80 °C for 4 hours to obtain the nano-silver coating.

[0086] Example 3

[0087] By weight components, disperse 6 parts of silver nitrate evenly in 100 parts of deionized water to obtain the first reaction solution; disperse 30 parts of polyethyleneimine evenly in 250 parts of deionized water to obtain the second reaction solution; mix the first reaction solution and the second reaction solution, adjust the pH value to 1, and stir evenly under the condition of an 80 °C oil bath to fully react to obtain the third reaction solution; filter, wash, and dry the third reaction solution to obtain nano-silver.

[0088] Take 1 part of the nano-silver and 0.1 part of sodium dodecyl sulfate, ultrasonically disperse them in deionized water, then add 3 parts of aniline and 5 parts of ammonium persulfate, adjust the pH value to 1, stir and react at 0 °C for 1 h, then perform solid-liquid separation, wash the obtained solid with ethanol twice, and then dry it in vacuum to obtain polyaniline-coated nano-silver.

[0089] Take 1 part of polyaniline-coated nano-silver, add 0.5 part of chloroacetic acid dissolved in deionized water, adjust the pH value of the solution to 1, and stir and react for 3 h,

[0090] After the reaction is completed, perform filtration, washing, and clean it with ethanol 3 times, and finally dry it at 60 °C to obtain chloroacetic acid-modified polyaniline-coated nano-silver.

[0091] Disperse 1 part of graphite evenly in 50 parts of concentrated sulfuric acid, add 4 parts of concentrated nitric acid, stir in an ice-water bath, and slowly heat to room temperature. Continue stirring and reacting for 10 hours to produce graphene oxide; after the reaction is completed, perform centrifugal washing multiple times to remove residual acidic substances and unreacted impurities, and then disperse in 200 parts of deionized water to obtain a graphene oxide aqueous dispersion; then perform ultrasonic treatment with a frequency of 70 kHz, a power of 250 W, and an ultrasonic time of 35 min to ensure complete dispersion of graphene oxide; then, add 5 parts of polyethyleneimine to the graphene oxide dispersion and continue stirring and reacting for 2.5 h to obtain a modified graphene oxide dispersion.

[0092] Add 1 part of the reducing agent sodium hydride to the modified graphene oxide dispersion, stir and react for 2 h. After the reaction ends, obtain a reduced graphene aqueous dispersion.

[0093] Take 1 part of the chloroacetic acid-modified polyaniline-coated silver nanoparticles, add 0.1 part of sodium dodecyl sulfate, and ultrasonically disperse in 100 parts of deionized water. Through ultrasonic treatment with a frequency of 50 kHz and a power of 300 W, ensure uniform dispersion of the silver nanoparticle particles; then mix with the reduced graphene aqueous dispersion to obtain a composite reaction solution; adjust the pH value of the solution to 1 and stir and react at 0 °C for 1 h. Separate the solid and liquid of the reactants, and then wash and dry to obtain reduced graphene-supported silver nanoparticles, that is, the coated and enhanced silver nanopowder.

[0094] Take 12 parts of the coated and enhanced silver nanopowder and add it to 60 parts of deionized water, and ultrasonically disperse it evenly.

[0095] Take 30 parts of epoxy resin and place it in a high-shear stirrer for standby.

[0096] Gradually add the coated and enhanced silver nanoparticle liquid and 1 part of the dispersant sodium dodecyl sulfate to the epoxy resin while stirring.

[0097] Add 6 parts of the curing agent dicyclohexylamine and 1.6 parts of the plasticizer dibutyl phthalate to the high-shear stirrer, and continue to stir evenly to ensure that the curing agent is completely distributed in the epoxy resin.

[0098] Finally, add 8 parts of ethanol to adjust the viscosity of the coating.

[0099] Pour the coating into a mold, place it in an oven, and cure at 70 °C for 4 hours to obtain the silver nanoparticle coating.

[0100] Comparative Example 1

[0101] By weight components, 6 parts of silver nitrate are uniformly dispersed in 100 parts of deionized water to obtain a first reaction solution; 30 parts of polyethyleneimine are uniformly dispersed in 250 parts of deionized water to obtain a second reaction solution; the first reaction solution and the second reaction solution are mixed, the pH value is adjusted to 1, and the mixture is stirred evenly under an oil bath condition at 80 °C for sufficient reaction to obtain a third reaction solution; the third reaction solution is subjected to suction filtration, washing, and drying to obtain silver nanoparticles.

[0102] Take 1 part of silver nanoparticles, add 0.5 part of chloroacetic acid and dissolve it in deionized water, adjust the pH value of the solution to 1, and stir and react for 3 h.

[0103] After the reaction is completed, suction filtration and washing are carried out, and it is washed 3 times with ethanol, and finally dried at 60 °C to obtain chloroacetic acid-modified silver nanoparticles.

[0104] Disperse 1 part of graphite uniformly in 50 parts of concentrated sulfuric acid, add 4 parts of concentrated nitric acid, stir in an ice-water bath, and slowly heat to room temperature, and continue to stir and react for 10 hours to generate graphene oxide; after the reaction is completed, carry out multiple centrifugal washings to remove residual acidic substances and unreacted impurities, and then disperse it in 200 parts of deionized water to obtain a graphene oxide aqueous dispersion; then carry out ultrasonic treatment, with a frequency of 70 kHz, a power of 250 W, and an ultrasonic time of 35 min to ensure that the graphene oxide is completely dispersed; then, add 5 parts of polyethyleneimine to the graphene oxide dispersion, and continue to stir and react for 2.5 h to obtain a modified graphene oxide dispersion.

[0105] Add 1 part of the reducing agent sodium hydride to the modified graphene oxide dispersion, stir and react for 2 h, and after the reaction is completed, obtain a reduced graphene aqueous dispersion.

[0106] Take 1 part of the chloroacetic acid-modified silver nanoparticles, add 0.1 part of sodium dodecyl sulfate, and ultrasonically disperse it in 100 parts of deionized water. Through ultrasonic treatment, with a frequency of 50 kHz and a power of 300 W, ensure that the silver nanoparticle particles are uniformly dispersed; then mix it with the reduced graphene aqueous dispersion to obtain a composite reaction solution; adjust the pH value of the solution to 1, stir and react at 0 °C for 1 h, separate the solid and liquid of the reactants, and then through washing and drying, obtain reduced graphene-supported silver nanoparticles, that is, the coated and enhanced silver nanopowder.

[0107] Take 12 parts of the coated and enhanced silver nanopowder, add it to 60 parts of deionized water, and ultrasonically disperse it evenly.

[0108] Take 30 parts of epoxy resin and place it in a high-shear stirrer for standby.

[0109] Gradually add the coated and enhanced silver nanoparticle liquid and 1 part of the dispersant sodium dodecyl sulfate to the epoxy resin, and stir while adding.

[0110] Add 6 parts of the curing agent dicyclohexylamine and 1.6 parts of the plasticizer dibutyl phthalate to the high-shear stirrer, and continue to stir evenly to ensure that the curing agent is completely distributed in the epoxy resin;

[0111] Finally, add 8 parts of ethanol to adjust the coating viscosity;

[0112] Pour the coating into a mold, place it in an oven, and cure it at 70 °C for 4 hours to obtain the nano-silver coating.

[0113] Compared with Example 3, in Comparative Example 1, the step of coating silver nanoparticles with polyaniline was omitted; other operation processes and process parameters were the same.

[0114] Comparative Example 2

[0115] By weight components, disperse 6 parts of silver nitrate evenly in 100 parts of deionized water to obtain a first reaction solution; disperse 30 parts of polyethyleneimine evenly in 250 parts of deionized water to obtain a second reaction solution; mix the first reaction solution and the second reaction solution, adjust the pH value to 1, and stir evenly under the condition of an 80 °C oil bath to fully react to obtain a third reaction solution; perform suction filtration, washing, and drying on the third reaction solution to obtain silver nanoparticles.

[0116] Take 1 part of the silver nanoparticles and 0.1 part of sodium dodecyl sulfate, ultrasonically disperse them in deionized water, then add 3 parts of aniline and 5 parts of ammonium persulfate, adjust the pH value to 1, stir and react at 0 °C for 1 h, then perform solid-liquid separation, wash the obtained solid twice with ethanol, and then dry it in vacuum to obtain silver nanoparticles coated with polyaniline.

[0117] Take 1 part of the silver nanoparticles coated with polyaniline, add 0.5 part of chloroacetic acid and dissolve it in deionized water, adjust the pH value of the solution to 1, and stir and react for 3 h.

[0118] After the reaction is completed, perform suction filtration, washing, and clean it 3 times with ethanol, and finally dry it at 60 °C to obtain chloroacetic acid-modified silver nanoparticles coated with polyaniline.

[0119] Take 12 parts of the chloroacetic acid-modified silver nanoparticles coated with polyaniline, add them to 60 parts of deionized water, and ultrasonically disperse them evenly;

[0120] Take 30 parts of epoxy resin and place it in a high-shear stirrer for standby;

[0121] Gradually add the coated enhanced silver nanoparticle liquid and 1 part of the dispersant sodium dodecyl sulfate to the epoxy resin while stirring.

[0122] Add 6 parts of the curing agent dicyclohexylamine and 1.6 parts of the plasticizer dibutyl phthalate to the high-shear stirrer, and continue to stir evenly to ensure that the curing agent is completely distributed in the epoxy resin;

[0123] Finally, add 8 parts of ethanol to adjust the viscosity of the coating;

[0124] Pour the coating into a mold, place it in an oven, and cure it at 70 °C for 4 hours to obtain the nano-silver coating.

[0125] Compared with Example 3, in Comparative Example 2, the step of preparing graphene oxide was omitted, and other operation processes and process parameters were the same.

[0126] Comparative Example 3

[0127] By weight components, disperse 6 parts of silver nitrate evenly in 100 parts of deionized water to obtain a first reaction solution; disperse 30 parts of polyethyleneimine evenly in 250 parts of deionized water to obtain a second reaction solution; mix the first reaction solution and the second reaction solution, adjust the pH value to 1, and stir evenly under the condition of an 80 °C oil bath to fully react to obtain a third reaction solution; perform suction filtration, washing, and drying on the third reaction solution to obtain nano-silver.

[0128] Take 1 part of the nano-silver and 0.1 part of sodium dodecyl sulfate, ultrasonically disperse them in deionized water, then add 3 parts of aniline and 5 parts of ammonium persulfate, adjust the pH value to 1, stir and react at 0 °C for 1 h, then perform solid-liquid separation, wash the obtained solid with ethanol 2 times, and then dry it under vacuum to obtain polyaniline-coated nano-silver.

[0129] Disperse 1 part of graphite evenly in 50 parts of concentrated sulfuric acid, add 4 parts of concentrated nitric acid, stir in an ice-water bath, and slowly heat to room temperature, continue to stir and react for 10 hours to generate graphene oxide; after the reaction is completed, perform centrifugal washing multiple times to remove residual acidic substances and unreacted impurities, and then disperse them in 200 parts of deionized water to obtain a graphene oxide aqueous dispersion; then perform ultrasonic treatment with a frequency of 70 kHz, a power of 250 W, and an ultrasonic time of 35 min to ensure that the graphene oxide is completely dispersed; then, add 5 parts of polyethyleneimine to the graphene oxide dispersion, and continue to stir and react for 2.5 h to obtain a modified graphene oxide dispersion.

[0130] Add 1 part of the reducing agent sodium hydride to the modified graphene oxide dispersion, stir and react for 2 h, and after the reaction is completed, obtain a reduced graphene aqueous dispersion.

[0131] Take 1 part of the polyaniline-coated nano-silver, add 0.1 part of sodium dodecyl sulfate, ultrasonically disperse it in 100 parts of deionized water, and ensure the uniform dispersion of nano-silver particles through ultrasonic treatment with a frequency of 50 kHz and a power of 300 W; then mix it with the reduced graphene aqueous dispersion to obtain a composite reaction solution; adjust the pH value of the solution to 1, stir and react at 0 °C for 1 h, perform solid-liquid separation on the reactants, and then through washing and drying, obtain reduced graphene-supported nano-silver, that is, the coated enhanced nano-silver powder.

[0132] Take 12 parts of coated and enhanced nano - silver powder, add it to 60 parts of deionized water, and disperse it evenly by ultrasonic wave.

[0133] Take 30 parts of epoxy resin and place it in a high - shear stirrer for standby.

[0134] Gradually add the coated and enhanced nano - silver liquid and 1 part of dispersant sodium dodecyl sulfate to the epoxy resin, stirring while adding.

[0135] Add 6 parts of curing agent dicyclohexylamine and 1.6 parts of plasticizer dibutyl phthalate to the high - shear stirrer, and continue to stir evenly to ensure that the curing agent is completely distributed in the epoxy resin.

[0136] Finally, add 8 parts of ethanol to adjust the viscosity of the coating.

[0137] Pour the coating into a mold, place it in an oven, and cure it at 70 °C for 4 hours to obtain the nano - silver coating.

[0138] Compared with Example 3, in Comparative Example 3, the step of modifying polyaniline with chloroacetic acid was omitted, and other operation processes and process parameters were the same.

[0139] Perform performance tests on the nano - silver coatings prepared in Examples 1 - 3 and Comparative Examples 1 - 3.

[0140] Antibacterial performance test: Refer to the method in HG / T 3950 - 2007 standard for testing, and select the data after 56 days of Staphylococcus aureus and Escherichia coli, and take the average value.

[0141] The abrasion resistance test is carried out according to the GB / T 1768 - 2006 standard by the rotating rubber grinding wheel method. Before the test, first prepare the specimen. Coat the coating evenly on the polished specimen, and set the coating thickness to 200 μm. After coating, the specimen needs to be left standing at room temperature for 10 days for use. When conducting the abrasion resistance test, first weigh the initial mass of the specimen, then install the specimen on the abrasion tester and connect the dust suction device. Set the corresponding load and rotation speed. The rotation speed in this experiment is 100 revolutions. After the machine starts to the set rotation speed, it will stop automatically. Take down the specimen and weigh it again. By comparing the mass difference between the two weighing results, the weight loss of the specimen under specific load and rotation speed conditions is obtained. The smaller the weight loss ratio, the stronger the abrasion resistance.

[0142] For the antistatic performance test, refer to the method in SJ / T11294 - 2003 "General Specification for Antistatic Floor Coatings" to test the initial surface resistance.

[0143] The test results are shown in Table 1 below.

[0144]

[0145] Analysis of antibacterial performance:

[0146] The nano-silver coatings of Examples 1, 2, and 3 showed extremely high antibacterial rates, especially against Staphylococcus aureus, with an antibacterial rate close to 100%. This is because the antibacterial effect of nano-silver mainly depends on the release of silver ions (Ag + +). These silver ions can bind to the cell wall and DNA of bacteria, destroying the cell membrane and inhibiting bacterial metabolism. Role of polyaniline: In the oxidized state, polyaniline can promote the release of silver ions through electron transfer, increasing the concentration of silver ions and further enhancing the antibacterial effect. Especially under the synergistic effect of graphene oxide, the release of silver ions is more uniform and persistent, thus enhancing the antibacterial performance. Synergistic effect of graphene: Partially reduced graphene not only provides a conductive channel to promote the rapid release of silver ions, but may also enhance its antibacterial effect through interaction with the bacterial cell membrane.

[0147] The antibacterial rate of Comparative Example 1 was relatively low. Especially for Staphylococcus aureus, the antibacterial rate was only 93.82%. This is because the nano-silver coating without polyaniline coating was used, and the silver particles were prone to agglomeration, resulting in a decrease in antibacterial activity. Secondly, the lack of the synergistic effect of polyaniline on the release of silver ions further decreased the antibacterial activity.

[0148] Due to the lack of the synergistic effect of graphene in Comparative Example 2, the overall electron migration speed of the material decreased, thereby slowing down the release rate of silver ions and resulting in a weakening of its antibacterial ability.

[0149] Analysis of wear resistance:

[0150] The coatings of Examples 1, 2, and 3 showed a relatively low wear weight loss rate, indicating that these composite coatings had good wear resistance. This is because the synergistic effect of polyaniline, graphene oxide, and nano-silver improved the mechanical strength and hardness of the coatings. Especially the introduction of graphene enhanced the hardness and toughness of the coatings, forming a strong network structure and improving the scratch resistance and wear resistance of the coatings.

[0151] Coating effect of polyaniline: The coating effect of polyaniline effectively prevented the agglomeration of nano-silver, ensuring the uniformity of the coating, thereby improving the overall wear resistance of the coating. Mechanical properties of graphene: The introduction of graphene enhanced the compressive and anti-friction abilities of the coating, forming a strong conductive network, which not only improved the conductivity but also enhanced the physical strength of the coating, thus improving the wear resistance.

[0152] In Comparative Example 1, the nano-silver coating lacking polyaniline coating showed a higher weight loss rate (8.6%) compared to Example 3. This difference is due to the lack of the protective effect and coating effect of polyaniline, resulting in a significant decrease in the wear resistance of the coating. Polyaniline coating can enhance the structural stability of the coating, prevent the aggregation or precipitation of silver particles, and enable the coating to better maintain its integrity during friction. The coating without polyaniline lacks this protection, is easily damaged by friction, and has a higher weight loss rate.

[0153] The weight loss rate of Comparative Example 2 reached 12.1%. This difference indicates that the coating without graphene composite lacks the necessary strength and stability, resulting in easy wear of the coating.

[0154] In Comparative Example 3, without chloroacetic acid-modified polyaniline, the binding force between polyaniline and epoxy resin and other components is weak. Without the help of carboxylic acid groups, the adhesion between polyaniline and the substrate is poor, resulting in easy detachment of the coating during friction and wear, causing a high wear weight loss.

[0155] Analysis of antistatic performance:

[0156] Resistance is an important indicator of conductive materials. Generally, the smaller the resistance, the better the conductivity of the material and the stronger the corresponding antistatic property. Antistatic property refers to the ability of a material to quickly release charges when encountering charge accumulation, thereby avoiding static charge accumulation and reducing static discharge phenomena. For coatings, good antistatic property means a lower surface resistance of the coating.

[0157] From the data in Table 1, it can be seen that the surface resistances of Examples 1, 2, and 3 are significantly lower than those of Comparative Groups 1, 2, and 3, indicating that the coatings of the examples have better conductivity and antistatic performance.

[0158] In Comparative Example 1, without polyaniline coating on nano-silver particles, silver particles agglomerated in the coating, reducing the effective surface area of silver and thus lowering the electron conduction efficiency. In addition, the lack of the electron transfer effect of polyaniline led to an unsmooth conduction path and a higher resistance.

[0159] In Comparative Example 2, the lack of graphene resulted in the absence of an effective conductive network in the coating. Graphene not only provides a channel for electron transfer for polyaniline but also helps improve the dispersion of nano-silver. In the absence of graphene, the electron migration efficiency is low, resulting in poor conductivity of the coating and a higher surface resistance.

[0160] In Comparative Example 3, the lack of chloroacetic acid-modified polyaniline led to insufficient polarity of polyaniline, resulting in poor compatibility with epoxy resin and graphene, affecting the formation of the conductive network. The oxidized state of polyaniline cannot fully promote the release of silver ions, reducing the conductivity of the coating, resulting in a higher surface resistance and being unfavorable for the elimination of static electricity.

[0161] As described above, it is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing coated enhanced nano silver powder, characterized in that: The steps include: S1: Silver nitrate was used as the silver source and polyethyleneimine was used as the reducing agent to prepare nanosilver; S2: using aniline and ammonium persulfate to coat and modify the nano-silver under acidic conditions to obtain polyaniline-coated nano-silver; S3: using chloroacetic acid to modify the polyaniline-coated nanosilver to obtain chloroacetic acid-modified polyaniline-coated nanosilver; S4: oxidizing graphite to prepare graphene oxide, and then modifying it with polyethyleneimine to obtain a modified graphene oxide dispersion; S5: partially reducing the graphene oxide using sodium hydride to obtain a reduced graphene aqueous dispersion; S6: using reduced graphene oxide to load the chloroacetic acid-modified polyaniline to coat the nano-silver, to obtain the coated enhanced nano-silver powder; The specific process of step S1 is: By weight, 5-8 parts of silver nitrate are uniformly dispersed in 100 parts of deionized water to obtain a first reaction liquid; 25-40 parts of polyethyleneimine are uniformly dispersed in 250 parts of deionized water to obtain a second reaction liquid; the first reaction liquid and the second reaction liquid are mixed, the pH value is adjusted to 1-2, and the mixture is stirred uniformly and fully reacted in an oil bath at 80-100° C. to obtain a third reaction liquid; the third reaction liquid is filtered, washed and dried to obtain nano silver; The specific process of step S2 is: take 1 part of the nanosilver and 0.1-0.2 parts of sodium dodecyl sulfate, ultrasonically disperse them in deionized water, then add 1.7-3.4 parts of aniline and 4-6 parts of ammonium persulfate, adjust the pH value to 1-2, stir the reaction at 0-5°C for 1-2h, then perform solid-liquid separation, wash the obtained solid with ethanol and then dry it to obtain polyaniline-coated nanosilver.

2. A method for preparing the coated enhanced nano silver powder according to claim 1, characterized in that: The specific process of step S3 is: Take 1 part of polyaniline-coated nanosilver, add 0.5-1.5 parts of chloroacetic acid and dissolve in deionized water, adjust the pH value of the solution to 1-2, stir and react for 3-5 hours, After the reaction is completed, the mixture is filtered, washed, and cleaned with ethanol, and finally dried at 60-80° C. to obtain chloroacetic acid-modified polyaniline-coated nanosilver.

3. A method for preparing the coated enhanced nano silver powder according to claim 1, characterized in that: The specific process of step S4 is as follows: 1-2 parts of graphite are uniformly dispersed in 50 parts of concentrated sulfuric acid, and 4-10 parts of concentrated nitric acid are added, stirred in an ice water bath, and slowly heated to room temperature, and stirred for 6-12 hours to generate graphene oxide; after the reaction is completed, centrifugal washing is performed multiple times to remove residual acidic substances and unreacted impurities, and dispersed in 200 parts of deionized water to obtain a graphene oxide aqueous dispersion; then ultrasonic treatment is performed at a frequency of 40-80 kHz, a power of 200-300W, and an ultrasonic time of 30-40min to ensure that the graphene oxide is completely dispersed; then, 2-8 parts of polyethyleneimine are added to the graphene oxide dispersion, and the stirring reaction is continued for 2-3h to obtain a modified graphene oxide dispersion.

4. A method for preparing the coated enhanced nano silver powder according to claim 1, characterized in that: The specific process of step S5 is: adding 1-2 parts of reducing agent sodium hydride to the modified graphene oxide dispersion, stirring and reacting for 2-3 hours to obtain a reduced graphene aqueous dispersion.

5. A method for preparing coated enhanced nano silver powder according to claim 1, characterized in that: The specific process of step S6 is: take 1 part of the chloroacetic acid modified polyaniline coated nanosilver, add 0.1-0.2 parts of sodium dodecyl sulfate, ultrasonically disperse it in 100 parts of deionized water, and perform ultrasonic treatment at a frequency of 40-60 kHz and a power of 200-400 W to ensure that the nanosilver particles are evenly dispersed; then mix it with the reduced graphene aqueous dispersion; obtain a composite reaction solution; adjust the solution pH value to 1-1.5, stir the reaction at 0-5°C for 1-2h, separate the reactant into solid and liquid, and then wash and dry it to obtain reduced graphene-loaded nanosilver, that is, the coated enhanced nanosilver powder.

6. Use of the coated enhanced nano silver powder prepared by the preparation method according to any one of claims 1 to 5 in coatings.

7. A nano silver coating, characterized in that: include: 10-15 parts of coated enhanced nano silver powder, 30-40 parts of epoxy resin, 5-10 parts of curing agent diaminocyclohexane, 1-2 parts of dispersant sodium dodecyl sulfate, 0.5-2 parts of plasticizer dibutyl phthalate and 5-10 parts of ethanol; the coated enhanced nano silver powder is prepared by any preparation method described in claims 1-5.

8. A method for preparing the nano silver coating according to claim 7, characterized in that: The steps include: Take 10-15 parts of coated enhanced nano silver powder, add it to 60 parts of deionized water, and disperse it evenly by ultrasonication; Take 30-40 parts of epoxy resin and place them in a high shear mixer for later use; Gradually add the coated enhanced nanosilver liquid into the epoxy resin while stirring; Add 5-10 parts of curing agent diaminocyclohexane and 0.5-2 parts of plasticizer dibutyl phthalate to the high shear mixer and continue to stir evenly to ensure that the curing agent is completely distributed in the epoxy resin; Finally, add 5-10 parts of ethanol to adjust the viscosity of the coating; The coating is poured into a mold, placed in an oven, and cured at 60-80° C. for 2-4 hours to obtain the nano silver coating.

Images