Cellulose antibacterial coating and preparation method thereof

Abstract

The invention discloses a cellulose antibacterial coating, and belongs to the technical field of cellulose, and the cellulose antibacterial coating comprises the following components in parts by weight: 8 to 15 parts of TPP modified cellulose, 1 to 2 parts of heptadecafluorodecyl trimethoxysilane, 1 to 1.5 parts of isocyanate, 0.3 to 0.7 part of nano silicon dioxide, 65 to 70 parts of absolute ethyl alcohol, and 18 to 20 parts of tetrahydrofuran. According to the invention, a flexible alkyl chain is combined with a rigid quaternary phosphonium salt TPP molecule, so that the limitation of a single mechanism of a traditional antibacterial agent is broken through; chemical bond anchoring is realized by a silane pre-hydrolysis oriented grafting technology; according to the method, electrostatic spraying and vapor deposition are combined, efficient coating preparation of a cross-scale base material is achieved, and a reliable solution is provided for large-scale application of the cellulose antibacterial coating in the fields of medical treatment, food packaging, environmental engineering and the like through multi-mechanism cooperation, chemical bonding and intelligent surface design.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of cellulose, and particularly relates to a cellulose antibacterial coating and a preparation method thereof. BACKGROUND

[0002] Traditional cellulose antibacterial coatings are mainly achieved through physical adsorption or blending modification, specifically including impregnation loading method, such as immersing cellulose into silver nanoparticle or quaternary ammonium salt solution, relying on hydrogen bond and van der Waals force adsorption; melt blending method and surface coating method. However, these methods have multiple technical challenges: the physically adsorbed antibacterial agent is easy to elute, and silver nanoparticles have the problem of uncontrolled slow release; silver ions have the problem of ecological toxicity due to biological accumulation. In terms of function, it is difficult to balance antibacterial and mildew resistance, and lack of antibiofilm ability; in the processing process, high-temperature melting will destroy the cellulose hydrogen bond network, resulting in a 30% decrease in strength, and solvent residue will also cause cytotoxicity. Although existing patents attempt to improve through chemical modification, there are still low gram-negative bacteria inhibition rates, and the core contradiction of drug resistance and long-acting has not been solved, so it is urgent to develop antibacterial coating technology with high grafting rate, zero release and multi-mechanism synergy. SUMMARY

[0003] In order to overcome the deficiencies of the prior art, the present application provides a cellulose antibacterial coating and a preparation method thereof, which realizes the improvement of cellulose antibacterial coating in long-acting, safety and performance by designing TPP modified cellulose.

[0004] The technical solutions to achieve the purpose of the present application are as follows: A cellulose antibacterial coating, by weight, comprising the following components: 8-15 parts of TPP modified cellulose, 1-2 parts of heptadecafluorodecyltrimethoxysilane, 1-1.5 parts of isocyanate, 0.3-0.7 parts of nano-silicon dioxide, 65-70 parts of anhydrous ethanol, and 18-20 parts of tetrahydrofuran.

[0005] Preferably, the isocyanate is selected from one or more of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and diphenylmethane diisocyanate.

[0006] A preparation method of a cellulose antibacterial coating, the raw materials are weighed by weight, heptadecafluorodecyltrimethoxysilane is added to tetrahydrofuran under argon atmosphere, TPP modified cellulose is ultrasonically dispersed for 5-10 min, nano-silicon dioxide and isocyanate are sequentially added, and finally anhydrous ethanol is added, and the cellulose antibacterial coating liquid is prepared by high-speed shearing dispersion at 8000-12000 rpm for 5-15 min. The cellulose antibacterial coating liquid is coated on the surface of the substrate, and the cellulose antibacterial coating is formed after drying.

[0007] The application of a cellulose antibacterial coating is to apply TPP modified cellulose to a new air system for household, including the following steps: The stainless steel filter screen is selected, and the cellulose antibacterial coating solution is electrostatically sprayed at 15 kV and a spraying distance of 25 cm after plasma activation at 50-70°C for 10-30 min with a 5% sodium hydroxide solution by mass fraction, to form a 4-5 μm coating on the surface of the filter screen, and after gradient curing, hexamethyldisilazane is vapor deposited, and the filter screen is installed downstream of the primary filter screen after being soaked in a 0.1 mol / L cold ammonium hexafluorophosphate acetone solution for 5-10 min.

[0008] The preparation method of the TPP modified cellulose includes the following steps: (a) Cellulose surface silanization: 1 eq of cellulose is placed in a vacuum drying oven and vacuum dried at 110-120°C for 20-24 h, transferred to an argon glove box, and pre-hydrolyzed silane coupling agent is added, reacted at 40-45°C for 1-2 h, and then washed with cold ethanol, cyclohexane in sequence three times by centrifugation to obtain silanized cellulose; (b) TPP molecule grafting: 1.2 eq of TPP molecules are dissolved in anhydrous N,N-dimethylformamide under an argon atmosphere, cooled to 0°C in an ice bath, and 1.8 eq of condensing agent and 0.3 eq of HOAt are added dropwise, followed by dropwise addition of silanized cellulose at 0°C, controlling the temperature ≤10°C, and after dropwise addition, avoiding light for 20-24 h, adding 1 eq of sodium bromide, and adding the reaction solution into cold diethyl ether to precipitate, washing with a 0.5 mol / L pre-cooled sodium bicarbonate solution, a saturated ammonium bromide acetone solution, and a 50% ethanol solution by mass fraction, and freeze-drying to obtain TPP modified cellulose.

[0009] Preferably, the pre-hydrolyzed silane coupling agent is 0.6 eq of silane coupling agent dissolved in a mixed solution of ethanol and water in a volume ratio of 4:1, and 0.1% acetic acid by mass fraction is added, stirred at 40°C for 1 h to obtain a silanol activation solution.

[0010] Preferably, the silane coupling agent is 3-aminopropyltriethoxysilane.

[0011] Preferably, the condensing agent is diisopropyl carbodiimide.

[0012] Preferably, the freeze-drying is dried at -70~-80°C for 2-3 h, then dried at -40~-50°C for 10-12 h, and finally dried at a gradient of 0.5°C / min from -30°C to 25°C for 6-7 h.

[0013] The preparation method of the TPP molecule includes the following steps: (1) Synthesis of 2-carboxyethyltriphenylphosphonium: 1 eq of 1-bromopropanoic acid and 1.5 eq of triphenylphosphine were mixed in acetonitrile, and the reaction was refluxed in an 80 °C oil bath for 2 h; after the reaction was completed, the solvent was removed by distillation under reduced pressure, and the product was separated and purified by silica gel column chromatography to obtain 2-carboxyethyltriphenylphosphonium; (2) Synthesis of the aminocarboxylic acid compound: 1 eq of N-Boc-L-phenylalanine was dissolved in N,N-dimethylformamide, and the mixture was cooled in an ice water bath at 0 °C; 1.2 eq of glycine methyl ester hydrochloride was neutralized, extracted with ethyl acetate, and concentrated to obtain glycine methyl ester; the solution was added to the reaction system, and 1.2 eq of N,N'-dicyclohexylcarbodiimide and 1.2 eq of 1-hydroxybenzotriazole were added in sequence; the reaction solution was stirred in an ice bath for 30-36 h, and then filtered through a sintered glass frit funnel, extracted, and purified by silica gel column chromatography to obtain Boc-L-phenylalaninyl glycine methyl ester; 1 eq of the product from the previous step was dissolved in methanol, and 1.7 eq of a 1 mol / L NaOH solution was added; the mixture was stirred at room temperature for 24 h; after the reaction was completed, the methanol was removed by distillation under reduced pressure, the residue was dissolved in water, washed with diethyl ether, and the aqueous layer was adjusted to a pH of 2.0-2.5 with a 1 mol / L HCl solution; the product was extracted and purified by silica gel column chromatography to obtain the target compound; 1 eq of the product from the previous step was dissolved in a 1:1 (by volume) mixture of N,N-dimethylformamide and ethyl acetate, and the solution was cooled in an ice water bath to 0 °C; 1.2 eq of 1-hydroxybenzotriazole, 1 eq of 6-aminohexanoic acid dissolved in ethyl acetate, and finally 1.2 eq of N,N'-dicyclohexylcarbodiimide were added in sequence; the ice bath was removed, and the reaction system was allowed to warm to room temperature; the mixture was continuously stirred for 24 h; the reaction solution was filtered to remove the byproduct N,N-dicyclohexylurea; the organic phase was washed with a 1 mol / L HCl solution and extracted; the target product was obtained in the form of a white powder after purification by silica gel column chromatography; 1 eq of the product from the previous step was placed in a reaction vessel, and 20 eq of formic acid was added; the mixture was stirred at room temperature for 24 h; after the reaction was completed, the formic acid was removed by distillation under reduced pressure; the residue was dissolved in water, and the pH of the aqueous phase was adjusted to 7.5-8.5 with a saturated Na2CO3 solution; the product was extracted with ethyl acetate and purified by basic alumina column chromatography to obtain the target aminocarboxylic acid compound in the form of a white solid; (3) Synthesis of the TPP molecule: 1 eq of the aminocarboxylic acid compound from the previous step was dissolved in a 1:1 (by volume) mixture of DMF and ethyl acetate, and 1 eq of 2-carboxyethyltriphenylphosphonium obtained in step (1) was added; the mixture was cooled in an ice water bath at 0 °C, and 0.8 eq of N,N'-dicyclohexylcarbodiimide and 0.8 eq of 1-hydroxybenzotriazole were added in sequence; the reaction system was gradually warmed to room temperature in an ice bath and continuously stirred for 48 h; the product was obtained after filtration, extraction, and purification by silica gel column chromatography; the structure of the target TPP molecule is shown below: .

[0014] Preferably, the extraction comprises the following steps: washing the organic phase with saturated brine, combining the organic phase and then extracting with ethyl acetate, drying with anhydrous sodium sulfate, and concentrating under reduced pressure to obtain the crude product.

[0015] Advantages

[0016] The present application comprises the following advantages: The present application realizes the improvement of cellulose antibacterial coating in long-acting, safety and function integration by designing TPP modified cellulose. Its core advantages are reflected in the following aspects: 1. Improved antibacterial property: through the synergistic effect of quaternary phosphonium salt cations and long alkyl chains, the coating achieves deep destruction of bacteria: the positive phosphonium ion destroys the membrane potential and increases the membrane permeability through positive and negative charge interaction, while the alkyl chain inserts into the bacterial lipid bilayer to form a physical membrane; this combined mechanism significantly improves the antibacterial efficiency, with an antibacterial rate of 99.99% for Staphylococcus aureus and Klebsiella pneumoniae.

[0017] 2. Super durability and environmental stability The coating forms Si-O-C covalent bonds through silane pre-hydrolysis directional grafting technology, with high antibacterial durability, superior to traditional physical adsorption type coatings.

[0018] 3. Improved mildew resistance The super-hydrophobic surface constructed by heptadecafluorodecyltrimethoxysilane makes the coating mildew resistance grade reach 0 level, which can effectively inhibit the adhesion and proliferation of microorganisms.

[0019] 4. Wide range of applications This technology can be adapted to cotton fabric, filter membrane, medical dressing and other substrates, and through electrostatic spraying and vapor deposition, the thickness of stainless steel filter coating can be precisely controlled, with strong cross-scale applicability, showing significant economic and social benefits.

[0020] In summary, the present application first designs the combination of flexible alkyl chain and rigid quaternary phosphonium salt TPP molecule, breaking through the limitations of traditional antibacterial agents with single mechanism; silane pre-hydrolysis directional grafting technology realizes chemical bond anchoring; electrostatic spraying combined with vapor deposition realizes efficient coating preparation of cross-scale substrates. This technology provides a reliable solution for the large-scale application of cellulose antibacterial coating in medical, food packaging, environmental engineering and other fields through multi-mechanism synergy, chemical bonding and intelligent surface design. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Synthesis route of TPP-modified cellulose; Figure 2 NMR spectrum of TPP molecule 1; Figure 3The infrared spectrograms of cellulose, TPP molecule 1, and TPP modified cellulose 1. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0023] In the embodiments, the experimental methods used are all conventional methods unless otherwise specified, and the materials, reagents, etc. used are all available from commercial channels unless otherwise specified.

[0024] The raw materials and equipment used in the examples and comparative examples will be described as follows: 2-carboxyethyl triphenyl phosphonium: self-made, and the preparation method is as follows: 1 eq of 1-bromopropanoic acid and 1.5 eq of triphenyl phosphine were mixed in acetonitrile, and the reaction was refluxed in an 80℃ oil bath for 2 h; after the reaction was completed, the solvent was removed by distillation under reduced pressure, and 2-carboxyethyl triphenyl phosphonium was obtained by silica gel column chromatography separation and purification; Amino carboxylic acid compound 1: self-made, and the preparation method is as follows: Dissolve 1 eq of N-Boc-L-phenylalanine in N,N-dimethylformamide, cool the mixture in an ice water bath, and then add 1.2 eq of glycine methyl ester hydrochloride after neutralization, ethyl acetate extraction, and concentration; add the solution to the reaction system, and then immediately add 1.2 eq of N,N'-dicyclohexyl carbodiimide and 1.2 eq of 1-hydroxybenzotriazole; stir the reaction solution in an ice bath for 30-36 h, and then filter, extract, and purify by silica gel column chromatography to obtain Boc-L-phenylalanine glycine methyl ester; dissolve 1 eq of the product in methanol, and then add 1.7 eq of 1 mol / L NaOH solution; stir at room temperature for 24 h, remove the methanol by evaporation under reduced pressure after the reaction is completed, wash the residue with ether, adjust the pH of the water phase to 2 with 1 mol / L HCl solution, extract, and purify by silica gel column chromatography to obtain the target compound; dissolve 1 eq of the product in a mixture of N,N-dimethylformamide and ethyl acetate (1:1, by volume), and cool to 0°C in an ice water bath; add 1.2 eq of 1-hydroxybenzotriazole, 1 eq of 6-aminohexanoic acid dissolved in ethyl acetate, and finally 1.2 eq of N,N'-dicyclohexyl carbodiimide; remove the ice water bath to allow the reaction system to warm to room temperature, and continue stirring for 24 h; remove the by-product N,N-dicyclohexyl urea by suction filtration, wash and extract the organic phase with 1 mol / L HCl solution, and purify by silica gel column chromatography to obtain the target product in the form of white powder; place 1 eq of the product in a reaction vessel, add 20 eq of formic acid, and stir at room temperature for 24 h; remove the formic acid by evaporation under reduced pressure after the reaction is completed, dissolve the residue in water, adjust the pH of the water phase to 7.5-8.5 with saturated Na2CO3 solution, extract with ethyl acetate, and purify by basic alumina column chromatography to obtain the target product, the amino carboxylic acid compound 1, in the form of white solid; Amino carboxylic acid compound 2: self-made, the difference from the preparation method of the amino carboxylic acid compound 1 is that 6-aminohexanoic acid is replaced by β-alanine, and other conditions remain unchanged, to obtain the amino carboxylic acid compound 2 Amino alkyl compound 3: self-made, the difference from the preparation method of the amino carboxylic acid compound 1 is that 6-aminohexanoic acid is replaced by n-hexylamine; Silane coupling agent: 3-aminopropyl triethoxysilane, product number A107147, purchased from Shanghai Aladdin Bio-Chem Technology Co., Ltd.; Condensing agent: diisopropyl carbodiimide, commercially available; Triphenylphosphine: product number T104475, purchased from Shanghai Aladdin Bio-Chem Technology Co., Ltd.; N-Boc-L-phenylalanine: purchased from Beijing Bnntech Co., Ltd.; Glycine methyl ester hydrochloride: product number G810396, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.; N,N'-dicyclohexyl carbodiimide: product number D106074, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; 1-hydroxybenzotriazole: product number 1059815, purchased from Tianjin Hensight Biochemical Technology Co., Ltd.; 6-aminohexanoic acid: product number A800336, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.; Cellulose: microcrystalline cellulose, 40-60 μm, product number 1091391, purchased from Shanghai Haohong Biological Medicine Technology Co., Ltd.; HOAt: product number H890201, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.; Nano-silicon dioxide: 50 nm, product number S817567, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.; n-Hexylamine: product number H105333, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Heptadecafluorodecyltrimethoxysilane: i.e. trimethoxy(1H,1H,2H,2H-heptadecafluorodecyl)silane, product number 1111125, purchased from Shanghai Haohong Biological Medicine Technology Co., Ltd.; Isocyanate: diphenylmethane diisocyanate, i.e. 4,4'-methylenebis(phenyl isocyanate), product number M106783, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; TPP molecule 1: self-made, the preparation method is as follows: 1 eq of the amino carboxylic acid compound 1 was dissolved in a mixed solvent of DMF: ethyl acetate with a volume ratio of 1:1, 1 eq of 2-carboxyethyl triphenyl phosphonium obtained in step (1) was added, the mixture was cooled in an ice water bath at 0°C, then 0.8 eq of N,N'-dicyclohexyl carbodiimide and 0.8 eq of 1-hydroxybenzotriazole were added in turn, the reaction system was gradually raised to room temperature under ice bath condition and continuously stirred for 48 h, filtered, extracted, and the target product TPP molecule was obtained by silica gel column chromatography, and its structure is shown in the following formula: .

[0025] TPP molecule 2: self-made, the preparation method is compared with that of TPP molecule 1, the difference is that the added amino carboxylic acid compound 1 is replaced by amino carboxylic acid compound 2, and other conditions are unchanged, to obtain TPP molecule 2, and its structure is shown in the following formula: .

[0026] TPP molecule 3: self-made, the difference between the preparation method and TPP molecule 1 is that the amino carboxylic acid compound 1 is replaced by the amino alkyl compound 3, and other conditions are unchanged, to obtain the TPP molecule 3, the structure is shown in the following formula: .

[0027] Molecule 4: self-made, the difference between the preparation method and TPP molecule 1 is that the 2-carboxyethyl triphenyl phosphonium is replaced by hexanoic acid, and other conditions are unchanged, to obtain the TPP molecule 4, the structure is shown in the following formula: ; Preparation example Preparation example 1 TPP modified cellulose 1: self-made, the preparation method is as follows: (a) Cellulose surface silanization: 1 eq of cellulose is placed in a vacuum drying oven, dried at 120℃ for 24 h, transferred to an argon glove box, and pre-hydrolyzed silane coupling agent is added, and reacted at 40℃ for 1~2 h, and then washed with cold ethanol, cyclohexane in turn for three times, to obtain silanized cellulose; (b) TPP molecule grafting: 1.2 eq of TPP molecule 1 is dissolved in anhydrous N,N-dimethylformamide under argon atmosphere, cooled to 0℃ in ice bath, 1.8 eq of condensing agent and 0.3 eq of HOAt are added dropwise, then silanized cellulose is added dropwise at 0℃, the temperature is controlled ≤10℃, after the dropwise addition is completed, it is reacted for 24 h in dark, 1 eq of sodium bromide is added, the reaction solution is precipitated by adding cold diethyl ether, washed with 0.5 mol / L pre-cooled sodium bicarbonate solution, saturated ammonium bromide acetone solution, and 50% ethanol solution, and then freeze-dried to obtain TPP modified cellulose 1.

[0028] Preparation example 2 TPP modified cellulose 2: self-made, the difference between the preparation method and TPP modified cellulose 1 is that the TPP molecule 1 used in step (2) is replaced by TPP molecule 2, and other conditions are unchanged, to obtain TPP modified cellulose 2; Preparation example 3 TPP modified cellulose 3: self-made, the difference between the preparation method and TPP modified cellulose 1 is that the TPP molecule 1 used in step (2) is replaced by TPP molecule 3, and other conditions are unchanged, to obtain TPP modified cellulose 3; Preparation example 4 TPP modified cellulose 4: self-made, the difference between the preparation method and TPP modified cellulose 1 is that the TPP molecule 1 used in step (2) is replaced by molecule 4, and other conditions are unchanged, to obtain TPP modified cellulose 4; Preparation example 5 TPP modified cellulose 5: self-made, the difference between the preparation method and TPP modified cellulose 1 is that step (1) cellulose surface silanization is not carried out, and other conditions are unchanged, and TPP modified cellulose 5 is obtained; Preparation Example 6 TPP modified cellulose 6: self-made, 1 eq of dry microcrystalline cellulose, 1.2 eq of TPP modified molecule 1 and 0.6 eq of pre-hydrolyzed silane coupling agent are added into a high-speed mixer, and dry mixing is carried out at 1000 rpm for 5 min; 0.5 eq of anhydrous ethanol is sprayed for wet mixing for 10 min, and then it is transferred into a twin-screw extruder for melt blending at 80℃, 200 rpm, 3 min, and then it is water-cooled, pelletized and pressed into tablets to obtain TPP modified cellulose 6.

[0029] Example

[0030] Examples 1-5 and Comparative Examples 1-3 Cellulose antibacterial coating: the raw materials are weighed by weight parts, 1.5 parts of heptadecafluorodecyltrimethoxysilane is added into 19.8 parts of tetrahydrofuran under an argon atmosphere, 8 parts of TPP modified cellulose is ultrasonically dispersed for 5 min, 0.5 parts of nano-silicon dioxide, 1.2 parts of isocyanate are added in turn, and finally 69 parts of anhydrous ethanol is added, and high-speed shearing dispersion is carried out at 10000 rpm for 10 min to prepare a cellulose antibacterial coating liquid; Table 1 Formulation of Examples 1-5 and Comparative Examples 1-3 (by weight parts)

[0031] The following is the test method of the performance parameters involved in the present application: 1. NMR spectrum: 400 MHz nuclear magnetic resonance instrument (Germany Bruker); 2. Fourier transform infrared spectrum (FTIR) determination: Spectrum two, USA PerkinElmer; 3. Antibacterial rate: detected according to GB / T 21866-2008, and the test bacteria are Staphylococcus aureus (AS1.89) and Klebsiella pneumoniae (AS1.1736); 4. Antibacterial durability: detected according to GB / T 21866-2008 "Antibacterial coating (paint film) antibacterial property determination method and antibacterial effect", 1 piece of 30W ultraviolet lamp with a wavelength of 253.7 nm is used, the ultraviolet lamp meets GB19258, the antibacterial coating test plate is 0.8m-1.0m away from the ultraviolet lamp, and irradiation is carried out for 100 h; 5. Antifungal property: detected according to GB / T 1741-2020 "Paint film mold resistance determination method".

[0032] Table 2 Performance test results of Examples 1-5 and Comparative Examples 1-3

[0033] As can be seen from the data in Table 2, Example 1 has the best comprehensive performance, with an antibacterial rate of 99.99% against Staphylococcus aureus and Klebsiella pneumoniae. This is due to the membrane penetration ability of the alkyl chain in the TPP molecule 1, which cooperates with the quaternary phosphonium salt cation to efficiently destroy the peptidoglycan layer; the antibacterial durability is due to the Si-O-Si covalent bond formed by silanization; and the level 0 antifungal performance is due to the superhydrophobic surface imparted by heptadecafluorodecyltrimethoxysilane. The amount of TPP modified cellulose added in Example 2 is relatively small, and the antibacterial rate is slightly reduced; Example 3 maintains an antibacterial rate of 99.74%, but the durability may be slightly reduced due to the influence of steric hindrance; the antibacterial rate of Example 4 is lower than that of Example 1, presumably because its alkyl chain is too short and the membrane penetration depth is insufficient; Example 5 cannot react with the silane coupling agent due to the lack of carboxyl groups, and the uneven distribution of the coating causes a decrease in the mildew resistance level; the antibacterial rate of Comparative Example 1 plummets to 68.2%, proving that the ion membrane breaking mechanism is irreplaceable; Comparative Example 2 is dominated by physical adsorption, and the durability is only 71% of that of Example 1; Although Comparative Example 3 maintains an initial antibacterial rate of 92% due to fluorosilane, the processing process destroys the cellulose hydrogen bond network, causing the durability to drop sharply to 52.8%.

[0034] In summary, the antimicrobial coating's golden triangle of performance—high bactericidal efficiency, long-lasting durability, and mildew resistance—requires simultaneous quaternary phosphonium salt ion membrane rupture, C6-C8 alkyl chain membrane penetration, and silane covalent anchoring. The three-dimensional synergistic effect of Example 1 is currently the optimal solution, while the structural defects of the comparative example demonstrate the irreplaceable nature of these mechanisms.

[0035] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A cellulose antibacterial coating, characterized in that: The composition comprises the following components in parts by weight: 8-15 parts of TPP-modified cellulose, 1-2 parts of heptadecafluorodecyltrimethoxysilane, 1-1.5 parts of isocyanate, 0.3-0.7 parts of nano-silicon dioxide, 65-70 parts of anhydrous ethanol, and 18-20 parts of tetrahydrofuran; the structure of the TPP-modified cellulose is shown in Formula 1: , formula 1.

2. The cellulose antibacterial coating according to claim 1, wherein The isocyanate is selected from one or more of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and diphenylmethane diisocyanate.

3. The cellulose antibacterial coating according to claim 1, wherein The preparation method of the TPP modified cellulose comprises the following steps: (a) Silanization of cellulose surface: Cellulose was placed in a vacuum drying oven, dried under vacuum, and then transferred to an argon glove box. A pre-hydrolyzed silane coupling agent was added and heated to 40-45°C. After the reaction, the silanized cellulose was washed to obtain the silanized cellulose. (b) TPP molecular grafting: Under an argon atmosphere, TPP molecules were dissolved in anhydrous N,N-dimethylformamide. The condensation agent and HOAt were added dropwise under ice bath conditions. Then, silanized cellulose was added dropwise under ice bath conditions. The temperature was controlled at ≤10°C. After the addition was completed, the reaction was carried out in the dark for 20-24 h. Sodium bromide was added, and the reaction solution was washed and freeze-dried to obtain TPP-modified cellulose.

4. The cellulose antibacterial coating according to claim 3, wherein The pre-hydrolyzed silane coupling agent is prepared by dissolving the silane coupling agent in a mixed solution of ethanol and water, adding an acetic acid aqueous solution, and stirring at 30-50°C to obtain a silanol activation solution; the silane coupling agent is 3-aminopropyltriethoxysilane; the condensation agent is diisopropylcarbodiimide; the freeze-drying step is drying at -70-80°C for 2-3 hours, then drying at -40-50°C for 10-12 hours, and finally drying at a gradient temperature of 0.5°C / min from -30°C to 25°C for 6-7 hours.

5. The cellulose antibacterial coating according to claim 3, wherein The preparation method of the TPP molecule comprises the following steps: (1) Synthesis of 2-carboxyethyltriphenylphosphonium: Bromopropionic acid and triphenylphosphine were mixed in acetonitrile and refluxed; after the reaction, the solvent was removed by distillation under reduced pressure, and 2-carboxyethyltriphenylphosphonium was obtained by separation and purification by silica gel column chromatography; (2) Synthesis of aminocarboxylic acid compounds: dissolve N-Boc-L-phenylalanine and cool in an ice-water bath. Neutralize, extract and concentrate glycine methyl ester hydrochloride to obtain glycine methyl ester. Immediately add N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole in sequence, stir in an ice bath, filter and extract through a sintered glass sand core funnel, and obtain Boc-L-phenylalanylglycine methyl ester through silica gel column chromatography. Then dissolve it in methanol, add NaOH solution, and stir at room temperature. After the reaction is completed, remove methanol under reduced pressure, dissolve the residue in water, wash with ether, adjust the pH of the aqueous layer to 2.0-2.5 with hydrochloric acid solution, extract and obtain the target compound through silica gel column chromatography. After dissolving the amine in a mixed solvent of ethyl acetate, place in an ice-water bath; sequentially add 1-hydroxybenzotriazole, 6-aminocaproic acid dissolved in ethyl acetate, and finally add N,N'-dicyclohexylcarbodiimide; remove the ice bath and allow the reaction system to warm to room temperature with continuous stirring; filter the reaction solution to remove the by-product N,N-dicyclohexylurea, wash the organic phase with hydrochloric acid solution, extract it, and obtain the target product as a white powder through silica gel column chromatography; place the product from the previous step in a reaction vessel, add formic acid, and stir at room temperature; after completion of the reaction, evaporate the formic acid under reduced pressure, dissolve the residue in water, adjust the pH of the aqueous phase to 7.5-8.5 with saturated sodium carbonate solution, extract it with ethyl acetate, and obtain the target product as a white solid aminocarboxylic acid compound through basic alumina column chromatography; (3) Synthesis of TPP molecule: The aminocarboxylic acid compound produced in the previous step was dissolved in a mixed solvent of DMF:ethyl acetate, and 2-carboxyethyltriphenylphosphonium obtained in step (1) was added. After cooling in an ice-water bath, N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole were added in sequence. The reaction system was gradually heated to room temperature in an ice bath and continuously stirred. The reaction system was filtered, extracted, and the target product TPP molecule was obtained by silica gel column chromatography. Its structure is shown in Formula 2: , formula 2.

6. The method for preparing a cellulose antibacterial coating according to any one of claims 1 to 5, characterized in that: The raw materials were weighed by weight. Heptadecafluorodecyltrimethoxysilane was added to tetrahydrofuran under an argon atmosphere. TPP-modified cellulose was added and ultrasonically dispersed for 5-10 min. Nanosilica and isocyanate were added in sequence, and finally anhydrous ethanol was added. The cellulose antibacterial coating liquid was prepared by high-speed shear dispersion at 8000-12000 rpm for 5-15 min. The liquid was then applied to the surface of the substrate and dried to form a cellulose antibacterial coating.

7. Use of a cellulose antibacterial coating according to any one of claims 1 to 5, characterized in that: Applying TPP modified cellulose to a household fresh air system includes the following steps: A stainless steel filter was selected and ultrasonically treated with sodium hydroxide solution at 50-70°C for 10-30 min. After plasma activation, a cellulose antibacterial coating liquid was electrostatically sprayed to form a 4-5 μm coating on the filter surface. After gradient curing and vapor deposition of hexamethyldisilazane, the filter was immersed in a cold ammonium hexafluorophosphate acetone solution and installed downstream of the primary filter.

Images