Triple silane co-hydration regulation and control mussel type functional antifouling paint treatment method

Abstract

The invention belongs to the technical field of antifouling paint treatment, and discloses a trisilane co-hydration regulation and control mussel type functional antifouling paint treatment method which comprises the following steps: step 1, preparing materials, step 2, synthesizing sulfobetaine silane, namely SBSi, step 3, preparing silane / TA coatings with different compositions, step 4, representing, step 5, measuring surface force, and step 6, evaluating antifouling performance. And 7, carrying out membrane separation on the oil-in-water emulsion. The reaction activity between APTES and TA is regulated and controlled by introducing FAS-17, the reaction rate of surface coating deposition is regulated and controlled, the compactness of the generated anti-fouling coating is controlled according to the requirement of a membrane base material pore structure, and then the composite coating with a dual anti-fouling mechanism is prepared by introducing FAS-17 with low surface energy and a hydrophilic SBSi polymer. The antifouling agent has double synergistic antifouling effects of promoting desorption of pollutants from the surface and preventing adsorption of the pollutants.

Description

Technical Field

[0001] This invention belongs to the field of antifouling coating treatment technology, specifically relating to a method for treating mussel-type functional antifouling coatings using triple silane co-hydration regulation. Background Technology

[0002] The discharge of oily wastewater has had a significant negative impact on ecosystems and human health. References: DSMa, H.Yi, C.Lai, XGLiu, XQHuo, ZWAn, L.Li, YKFu, BSLi, MMZhang, L.Qin, SYLiu, L.Yang, Critical review of advanced oxidation processes in organic wastewater treatment, Chemosphere 275 (2021); WQZhang, YTLiu, FBTao, YHAn, Y.Zhong, ZCLiu, ZCHu, XTZhang, XMWang, An overview of biomass-based Oil / Water separation materials, Separation and Purification Technology 316 (2023); and CLZhao, JYZhou, Y.Yan, LWYang, GHXing, HYLi, P.Wu, MYWang, HLZheng, Application of coagulation / flocculation in oily wastewater treatment: A review, Science of the Total Environment 765 (2021) Stable oil-in-water emulsions typically remain stable over long periods, primarily due to their small droplet size and the addition of surfactants that enhance stability.However, these characteristics present considerable challenges in the separation and processing of emulsions. References: LXHan, HCBi, HZHuang, M.Ye, JWSun, LTSun, Surface-engineered graphene-based multi-level filter materials for one-step separation of complex oil-in-water emulsions, Separation and Purification Technology 339(2024); H.Matsubara, Y.Tokiwa, A.Masunaga, H.Sakamoto, K.Shishida, K.Ohshima, A.Prause, M.Gradzielski, Surfacefreezing of cationic surfactant-adsorbed films at the oil-water interface: Impact on oil-in-water emulsion and pickering emulsion stability, Advances in Colloid and Interface Science 334(2024); B.Xiang, JLGong, YQSun, WHYan, RRJin, J.Li, High permeability PEG / MXene@MOF membrane with stable Interlayer spacing and efficient fouling resistance for continuous oily wastewater purification, Journal of Membrane Science 691 (2024) and S. Zarghami, T. Mohammadi, M. Sadrzadeh, B. Van der Bruggen, Superhydrophilic and underwater superoleophobic membranes - review of synthesis methods, Progress in Polymer Science 98 (2019). Developing effective water treatment methods is crucial for mitigating the adverse environmental impacts of oily wastewater and ensuring the sustainable use of water resources.Membrane filtration has become an effective method for treating oil-in-water emulsions. Compared with other separation technologies, membrane filtration has high separation efficiency and relatively low material cost, providing a reliable and simple strategy for the purification of oily wastewater. References: HYLi,Q.Zhong,Q.Sun,B.Xiang,J.Li,Upcycling Waste Pine Nut Shell Membrane for Highly Efficient Separation of Crude Oil-in-Water Emulsion, Langmuir 38(11)(2022)3493-3500; YYLin,F.Yu,ZJYu,XYLin,F.Lin,RRLiu,Q.Chen,JLDu,X.Huang,ALGu,XWLi,S.Arcadio,SQFang,WYYe,JYLin,Mussel-inspired superhydrophilic and antibacterial membranes for effective gravity-driven separation of oil-in-water emulsions,Separation and Purification Technology 341 (2024) and WB Zhang, YZ Zhu, X. Liu, D. Wang, JY Li, L. Jiang, J. Jin, Salt-Induced Fabrication of Superhydrophilic and Underwater Superoleophobic PAA-g-PVDF Membranes for Effective Separation of Oil-in-Water Emulsions, Angewandte Chemie-International Edition 53(3)(2014) 856-860. However, despite the significant advantages of membrane filtration, oil droplets, organic contaminants, and other impurities inevitably accumulate on the membrane surface during membrane separation.This surface fouling severely impacts membrane performance, leading to increased flow resistance, decreased permeability, and increased energy consumption (see references: P. Dansawad, YJ Yang, X. Li, XPShang, YXLi, ZWGuo, YSQing, SYZhao, SMYou, WLLi, Smart membranes for oil / water emulsions separation: A review, AdvancedMembranes 2 (2022) and L. Xu, TQXu, WJLiu, T.Zuo, T.Wang, Y.Cai, JWZhang, LMYi, Heterogeneous wettability membrane for efficient demulsification and separation of oil-in-water emulsions, Chemical Engineering Journal 489 (2024)). Therefore, many membrane materials require frequent cleaning and maintenance to ensure their separation performance, which not only increases operating costs but also limits the long-term economic viability of membrane filtration technology.

[0003] To improve the separation performance and extend the service life of membranes, many studies have focused on designing hydrophilic membranes by integrating hydrophilic materials into the micron or nanostructure of the membrane. References: WB Zhang, YZ Zhu, X. Liu, D. Wang, JY Li, L. Jiang, J. Jin, Salt-Induced Fabrication of Superhydrophilic and Underwater Superoleophobic PAA-g-PVDF Membranes for Effective Separation of Oil-in-Water Emulsions, Angewandte Chemie-International Edition 53(3)(2014)856-860; LW Chen, SL Huang, XLTian, ​​Suppression of membrane fouling inemulsion separation through a covalently grafted liquid-like layer, Separation and Purification Technology. 338 (2024), N. H. Smail, W. N. W. Smail, A. F. Smail, H. Hasbullah, N. Yusof, F. Aziz, J. Jaafar, Hydropic polymer-based membrane for organic wastewater treatment: A review, Separation and Purification Technology 233 (2020) and Z. T. Yu, F. C. Yang, P. C. Tang, Z. G. Guo, Double bioinspired of robust BaSO4 / SnO2 membrane with anti-crude oil adhesion and remarkable emulsion separation, Separation and Purification Technology 357 (2025). This antifouling strategy relies on attracting water molecules to form a hydration layer, thereby creating a physical barrier between the membrane surface and the fouling. For example, Zhao et al. prepared a surface coating with excellent antifouling properties in complex biofluids by coupling sulfobetaine methacrylate (SBMA) with bovine serum albumin (BSA).This coating effectively prevents the accumulation of oil droplets and organic contaminants on the coating surface, significantly improving the membrane's antifouling ability and service life. (Reference: ZQ Zhao, MFPan, CY Qiao, L. Xiang, X. Liu, WSYang, XZ Chen, HB Zeng, Bionic Engineered Protein Coating Boosting Anti-Biofouling in Complex Biological Fluids, Advanced Materials 35(6)(2023).) The zwitterionic SBMA coating exhibits significant interfacial hydration and steric repulsion effects against various types of fouling, indicating that introducing hydrophilic functional groups can significantly improve the antifouling performance of the coating surface. However, despite initial success, this strategy still has certain limitations in directly removing fouling from the membrane surface. Specifically, the hydration layer only provides protection for the membrane surface; once oily fouling forms under high external pressure or other operational stresses on the membrane material, the higher surface energy of the hydrophilic surface makes fouling removal difficult. To address this issue, researchers attempted to introduce low surface energy components onto the membrane surface to enhance the fouling release capacity of the hydrophilic membrane, thereby making the fouling easier to separate.This dual-functional design, combining hydrophilicity and low surface energy, not only maintains the membrane's high antifouling performance but also improves its operability and economy in practical applications. References: YJCho, HSSundaram, CJWeinman, MYPaik, MDDimitriou, JAFinlay, MECallow, JACallow, EJKramer, CKOber, Triblock Copolymers with Grafted Fluorine-Free, Amphiphilic, Non-Ionic Side Chains for Antifouling and Fouling-Release Applications, Macromolecules 44(12)(2011)4783-4792; HSGoo, PGChen, S.Tian, ​​YMMa, QSLi, CYWen, J.Yang, L.Zhang, Amphiphilic Marine Antifouling Coatings Based on a Hydrophilic Polyvinylpyrrolidone and Hydrophobic Fluorine-Silicon-Containing Block Copolymer, Langmuir 36(48)(2020)14573-14581.33、XWSun,CQWu,JHHu,XYHuang,GLLu,C.Feng,Antifouling SurfacesBased on Fluorine-Containing Asymmetric Polymer Brushes:Effect of Chain Length of Fluorinated Side Chain, Langmuir 35(5)(2019)1235-1241 and A.van Dam,MMJSmulders,H.Zuilhof,Self-healing antifouling polymer brushes:Effects of degree of fluorination,Applied Surface Science 579(2022). Including, Dam successfully grafted polymer brushes with different side chain lengths and degrees of fluorination onto silicon surfaces.Due to the low surface energy of these polymers, the grafted silicon surface exhibits significant antifouling properties against organic polymer fouling (Reference: A. van Dam, MMJS mulders, H. Zuilhof, Self-healing antifouling polymerbrushes: Effects of degree of fluorination, Applied Surface Science 579 (2022)). However, the application of low surface energy components also presents its own challenges. Many studies have reported that components, such as fluorinated chains, have poor stability on film surfaces and are easily detached under slight disturbances such as changes in solution conditions or mechanical abrasion. These problems limit the long-term effectiveness and reliability of low surface energy materials in practical applications, necessitating further optimization of their structure and bonding methods to enhance their robustness. (References: A. Milionis, E. Loth, I.S. Bayer, Recent advances in the mechanicaldurability of Superhydrophobic materials, Advances in Colloid and Interface Science 229(2016)57-79; JHZhi, LZZhang, YYYang, J. Zhu, Mechanicaldurability of superhydrophobic surfaces: The role of surface modification technologies, Applied Surface Science 392(2017)286-296). This phenomenon not only weakens the antifouling effect but also allows detached substances to potentially cause secondary environmental pollution. Therefore, there is an urgent need to develop a stable antifouling coating that combines antifouling and decontamination strategies to optimize the performance of oil-water separation membranes and extend their service life.

[0004] In marine organisms such as mussels and barnacles, mussel foot proteins (mfps) achieve strong surface adhesion by forming a bioadhesive layer and rapidly solidifying it (see references: JSChen, LBHan, JFLiu, HBZeng, Mussel-Inspired Adhesive Hydrogels: Chemistry and Biomedical Applications, Chinese Journal of Chemistry 41(24)(2023)3729-3738 and JSChen, QYPeng, JFLiu, HBZeng, Mussel-Inspired Cation-π Interactions: Wet Adhesion and Biomimetic Materials, Langmuir 39(49)(2023)17600-17610). This adhesion process relies on the Schiff base reaction between catechol and the amino groups in the protein, thus achieving a firm and stable attachment.Inspired by this mechanism, researchers have extensively developed mussel-inspired surface coatings with high surface affinity and excellent stability. References: H. Lee, SMDellatore, WMMiller, PBMessersmith, Mussel-inspired surface chemistry for multifunctional coatings, Science 318(5849)(2007)426-430; WSYYang, MFPan, JWZhang, L.Zhang, FCLin, X.Liu, C.Huang, XZChen, JMWang, B.Yan, HBZeng, Universal Strategy for Constructing Robust and Antifouling Cellulose Nanocrystal Coating, Advanced Functional Materials 32(8)(2022); and XYZhang, MYLiu, YLZhang, B.Yang, Y.Ji, L.Feng, L.Tao, SXLi, Y.Wei, Combining mussel-inspired chemistry and The Michael addition reaction to disperse carbon nanotubes, Rsc Advances 2(32)(2012)12153-12155. Including Yang et al., who reported a mussel-like coating strategy composed of tannic acid (TA), polyethyleneimine (PEI), and vanadium (V), which exhibited robust adhesion on various substrates and good anchoring ability for cellulose nanocrystals (CNCs). The obtained CNC coatings showed excellent antifouling properties. Reference: WS Yang, MFPan, JW Zhang, L. Zhang, FCLin, X. Liu, C. Huang, XZ Chen, JMWang, B. Yan, HB Zeng, A Universal Strategy for Constructing Robustand Antifouling Cellulose Nanocrystal Coating, Advanced Functional Materials 32(8)(2022). In summary, integrating hydrophilic components with low surface energy components into robust coatings by referencing the adhesion mechanism of mussels is a very promising method.However, most existing mussel-inspired coatings face numerous challenges in practical applications, primarily due to the uncontrollable and rapid nature of the Schiff base reaction and Michael addition reaction, which leads to the formation of aggregates on the membrane surface. These aggregates not only cause uneven surface coverage but also clog the membrane's porous structure, thereby significantly reducing the water permeation flux during separation. Therefore, it is urgent to optimize the synthesis method of the coating to achieve uniform coverage and maintain the high permeability of the membrane. References: WZQiu,GPWu,ZKXu, Robust Coatings via Catechol-Amine Codeposition: Mechanism, Kinetics, and Application, Acs Applied Materials & Interfaces 10(6)(2018)5902-5908; SJYang,LYZou,C.Liu,Q.Zhong,ZYMa,J.Yang,J.Ji,P.Müller-Buschbaum,ZKXu, Codeposition of Levodopa and Polyethyleneimine: Reaction Mechanism and Coating Construction, Acs Applied Materials & Interfaces 10(6)(2018)5902-5908; SJYang,LYZou,C.Liu,Q.Zhong,ZYMa,J.Yang,J.Ji,P.Müller-Buschbaum,ZKXu,Codeposition of Levodopa and Polyethyleneimine:Reaction Mechanism and Coating Construction, Acs Applied Materials & Interfaces 10(6)(2018)5902-5908. Materials & Interfaces 12(48)(2020)54094-54103 and PB Zhang, WJH Hu, M.Wu, L.Gong, AQTang, L.Xiang, BKZhu, LPZhu, HBZeng, Cost-Effective Strategy for Surface Modification via Complexation of Disassembled Polydopamine with Fe(III)Ions, Langmuir 35(11)(2019)4101-4109. To address this issue, regulating the reactivity in mussel-inspired coating processes is crucial for achieving uniform and robust surface coatings. In recent years, numerous studies have shown that introducing different end groups during silane co-hydration can effectively regulate the coating structure. This strategy not only optimizes the chemical properties of the coating but also significantly improves its physical properties. The silane co-hydration method provides a new approach for preparing superhydrophilic / low surface energy antifouling coatings.References: GSNambafu, N.Kim, J.Kim, Hydrophobic coatings prepared using various dipodalsilane-functionalized polymer precursors, Applied Surface Science Advances 7(2022), M.Shateri-Khalilabad, MEYazdanshenas, One-pot sonochemical synthesis of superhydrophobic organic-inorganic hybrid coatings on cotton cellulose, Cellulose 20(6)(2013)3039-3051 and HXWang, J.Ding, YHXue, XGWang, T.Lin, Superhydrophobic fabrics from hybrid silica sol-gel coatings: Structural effect of precursors on wettability and durability, Journal of Materials Research 25(7)(2010)1336-1343. Therefore, based on the above analysis, it is speculated that combining low surface energy fluorinated silanes and zwitterionic silanes in the mussel-inspired coating process may be an effective strategy to regulate the Schiff base reaction rate, thereby achieving the formation of a uniform and robust curable coating. Summary of the Invention

[0005] This invention proposes a method for treating mussel-type functional antifouling coatings using triple silane co-hydration. The aim is to regulate the reaction activity between APTES and TA by introducing FAS-17, thereby controlling the reaction rate of surface coating deposition. The density of the generated antifouling coating is controlled according to the required pore structure of the membrane substrate. Furthermore, by introducing low surface energy FAS-17 and hydrophilic SBSi polymer, a composite coating with a dual antifouling mechanism is prepared, exhibiting a dual synergistic antifouling effect that promotes the desorption of pollutants from the surface and prevents the adsorption of pollutants.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for treating mussel-type functional antifouling coatings using triple silane co-hydration regulation, the method comprising the following steps:

[0007] Step 1, Materials:

[0008] Tannic acid (TA), >99.5%; 3-aminopropyltriethoxysilane (APTES), >98%; 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-17), >97%; Ethanol >99.5%; Bovine serum albumin (BSA), >98%; Humic acid (HA), >98%; Pepsin >98.0%; Hemoglobin >98%; Oil Red O; Sodium dodecyl sulfate (SDS), >99%; NaCl >99%; Phosphate-buffered saline tablets (PBS); Pentane >99%; Hexane >98.5%; Toluene >99.5%; Acetone >99.5% were purchased from Fisher Scientific; Durapore PVDF membrane (approximately 0.22 μm pore size, approximately 47 mm diameter) was purchased from Millipore. Co., Ltd.; The deionized water used in this method, i.e., DI water, comes from Milli-Q Advantage A10, and the milk is purchased from the local market;

[0009] Step 2, Synthesis of sulfobetaine silane, i.e., SBSi:

[0010] According to previous studies, SBSi was synthesized by dissolving 5g DMASi and 3g 1,3-propane sulfone in 25mL of anhydrous acetone and reacting with nitrogen at room temperature for 6h. The mixture was then filtered to produce a white solid product, which was then washed with anhydrous acetone and dried under vacuum.

[0011] Step 3, Preparation of silane / TA coatings with different compositions:

[0012] First, the substrate surface, including the PVDF film, silicon wafer, QCM sensor, and AFM probe, was repeatedly washed with alternating ethanol and water. It was then ultrasonically treated for 15 minutes in a 50 / 50 volume fraction water / ethanol mixture, followed by 15 minutes in a UV / ozone cleaner before use. For the preparation of the APZWF / TA coated substrate, a 50 / 50 volume fraction Tris-HCl solution (pH 8.5) was first prepared, followed by the addition of different concentrations of 3-aminopropyltriethoxysilane (APTES), sulfobetaine silane (SBSi), and 1H,1H,2H,2H perfluorodecyltriethoxysilane. Oxysilane, namely FAS-17, was shaken on a shaker at 300 rpm for 10 minutes; then 2 mg / mL of tannic acid, namely TA, was added, and the mixture was shaken on a shaker at 300 rpm for 10 minutes; finally, the substrate material was added, and the mixture was shaken on a shaker at 100 rpm for 8 hours, i.e., coating deposition was completed at room temperature. The modified surface was then thoroughly rinsed with water and ethanol to remove impurities, and dried with nitrogen to obtain the APZWF / TA coated substrate; AP / TA coated substrates can be manufactured using the same method, including those without SBSi and FAS-17, and APZW / TA coated substrates without FAS-17.

[0013] Step 4, Material Characterization:

[0014] The surface chemical properties of the prepared coatings were analyzed using X-ray photoelectron spectroscopy (XPS) on an AXIS Ultra (Kratos Analytical) microscope. The hydrophilicity and hydrophobicity of the prepared coatings were determined using a contact angle goniometer. The surface morphology of the prepared coatings was characterized using atomic force microscopy (AFM) in air in tapping mode. The variations in surface morphology and elemental distribution of different coatings were characterized using a Zeiss Sigma 300VP-FESEM field emission scanning electron microscope and energy-dispersive X-ray spectroscopy (EDS).

[0015] Step 5, Surface force measurement:

[0016] AFM surface force measurements were performed using an Asylum Research MFP-3D probe. Silica microspheres were attached to a tipless AFM cantilever beam using a two-component epoxy resin adhesive to prepare silica sphere probes. The prepared silica probes were then placed in a UV / ozone cleaner for 15 minutes. During the surface force measurement experiment, the silica sphere probes coated with AP / TA, APZW / TA, and APZWF / TA coatings, along with the silicon surface, were immersed in a solution containing 10 mM TA. Surface force tests were performed by driving the silica probes close to the underlying silicon surface at a fixed speed of 1 μm / s. The interaction forces were then determined using Hooke's law based on the stiffness coefficient of the AFM probes.

[0017] Step 6, Evaluation of the anti-fouling performance of the coating surface:

[0018] The anti-fouling properties of the coating were determined by measuring the adsorbed mass of dirt on a silica sensor chip covered with an APZWF / TA coating in real time using a quartz crystal microbalance (QCM). Based on the frequency changes detected by the QCM, the mass change on the silica sensor chip due to dirt adsorption was calculated using the Sauerbrey equation.

[0019]

[0020] Where Δm is the mass change on the sensor, Δf is the frequency change of the sensor (Hz), and C is 17.7 ng Hz. - 1 cm -2 The constant is n, where n is the number of overtones;

[0021] The antifouling performance of the APZWF / TA coating was determined using O-PTIR (non-contact submicron visible probe infrared spectroscopy), mIRage, Photothermal Spectroscopy Corp, CA. A 20% milk solution was used as a model for biological contaminants. O-PTIR spectroscopy showed that the characteristic peak of milk was located at 1650 cm⁻¹. -1 Then, by setting the IR wavelength to its corresponding peak, the surface coverage of the milk stain sample was imaged at a resolution of 500 nm using an IR microscope. The antifouling performance of the coating surface was described by the change in the area distribution ratio of surface contaminants using ImageJ statistics.

[0022] Step 7, Membrane separation performance test of oil-in-water emulsion:

[0023] The separation performance of an APZWF / TA-coated PVDF membrane was determined by vacuum filtration separation of an oil-in-water emulsion containing 1 wt% toluene, pentane, and hexane, and 20 ppm SDS (O / W emulsion). The emulsion was prepared using a T-18 Ultra Turrax homogenizer with stirring at 15,000 rpm for 10 minutes. The size distribution of the prepared emulsion was characterized by dynamic light scattering (DLS) using a Zetasizer Nano ZSP. During the oil-water separation test, the membrane was immobilized in a dead-end filtration device, and the permeate flux through the membrane, J, was calculated using the following formula:

[0024]

[0025] Where ΔV is the volume of filtrate passing through the membrane during the filtration duration, S is the effective membrane area, and ΔP is the pressure difference between ambient pressure and vacuum pressure. The filtrate is then collected and characterized again using DLS.

[0026] Preferably, in step 7, in order to evaluate the membrane's anti-biofouling properties during O / W emulsion separation, the change in water flux through the membrane after O / W emulsion separation with added BSA and HA is measured and recorded in real time after each cycle, and the membrane is thoroughly washed after each cycle of emulsion separation and before starting the next cycle.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. By introducing FAS-17 to regulate the reactivity between APTES and TA, the reaction rate of surface coating deposition is controlled, and the density of the generated antifouling coating is controlled according to the required pore structure of the membrane substrate.

[0029] 2. By introducing low surface energy FAS-17 / hydrophilic SBSi polymer, a dual-mechanism antifouling composite material was prepared, which has a dual synergistic antifouling effect of promoting the desorption of pollutants from the surface and preventing the adsorption of pollutants. Attached Figure Description

[0030] Figure 1 This invention provides (a) a schematic diagram of the coating process and (b) a diagram of the chemical reactions during the coating formation process.

[0031] Figure 2 For characterizing the coating structure, (a) XPS full spectrum of APZWF / TA coating, (b) AP / TA coating, (c) APZW / TA coating, (d) C1s high-resolution spectrum of APZWF / TA coating, (e) effect of SBSi concentration on water contact angle of APZWF / TA coating, (f) effect of FAS-17 concentration on water contact angle of APZWF / TA coating;

[0032] Figure 3 The paper presents schematic diagrams and results of surface force measurements under different coating conditions in this invention, specifically including: (a) AP / TA coating condition, (b) APZW / TA coating condition, and (c) APZWF / TA coating condition; under these conditions, force distribution histograms and surface force curves between the silica probe and the silica substrate with (a1) AP / TA coating, (b1) APZW / TA coating, and (c1) APZWF / TA coating are shown respectively; in addition, the figures also include atomic force microscopy (AFM) images of the silica substrate under the corresponding coating conditions, namely (a2) AP / TA coated, (b2) APZW / TA coated, and (c2) APZWF / TA coated samples;

[0033] Figure 4 The images show O-PTIR images of bio-organic fouling detected on (a) bare silica, AP / TA-coated silica, APZW / TA-coated silica, and APZWF / TA-coated silica substrates, (b) milk fouling coverage on bare silica, AP / TA-coated silica, APZW / TA-coated silica, and APZWF / TA-coated silica substrates, (c) frequency variations caused by BSA adsorption on bare silica and APZWF / TA-coated silica sensor chips, and (d) variations in the amount of different types of bio-organic fouling adsorbed on the surface.

[0034] Figure 5 The images show SEM images of the surfaces of (a) bare PVDF membrane, (b) PVDF membrane covered with AP / TA coating, (c) PVDF membrane covered with APZW / TA coating, and (d) PVDF membrane covered with APZWF / TA coating, and (e) EDS spectrum of the PVDF membrane covered with APZWF / TA coating.

[0035] Figure 6 The following are examples of the water contact angle of (a) bare PVDF membrane and PVDF membrane covered with APZWF / TA coating over time, (b) underwater oil contact angle of PVDF membrane covered with APZWF / TA coating at different pH values, (c) underwater oil adhesion test of bare PVDF membrane, and (d) underwater oil droplet adhesion test of PVDF membrane covered with APZWF / TA coating.

[0036] Figure 7 The present invention provides: (a) a schematic diagram of the apparatus setup for membrane filtration; (b) a particle size distribution diagram of the oil-in-water emulsion before filtration; (c) a particle size distribution diagram of the filtrate collected after filtration; (d) pure water flux of PVDF membranes coated with AP / TA, APZW / TA, and APZWF / TA; (e) water flux of PVDF membranes coated with APZWF / TA under different solution conditions; (f) emulsion separation performance of PVDF membranes coated with APZWF / TA for different oil products; and (g) emulsion separation performance of PVDF membranes coated with APZWF / TA for protein-containing emulsions.

[0037] Figure 8The following are examples of the present invention: (a) circulating O / W emulsion separation water flux of PVDF membranes covered with APZWF / TA coating, (b) real-time comparison of O / W emulsion separation water flux among PVDF membranes covered with AP / TA, APZW / TA and APZWF / TA coatings, (c) PVDF membrane covered with AP / TA coating, (d) PVDF membrane covered with APZW / TA coating, and (e) underwater oil jet experiment of PVDF membrane covered with APZWF / TA coating. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] A method for treating mussel-type functional antifouling coatings using triple silane co-hydration regulation includes the following steps:

[0040] Step 1, Materials:

[0041] Tannic acid (TA), >99.5%; 3-aminopropyltriethoxysilane (APTES), >98%; 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-17), >97%; Ethanol >99.5%; Bovine serum albumin (BSA), >98%; Humic acid (HA), >98%; Pepsin >98.0%; Hemoglobin >98%; Oil Red O; Sodium dodecyl sulfate (SDS), >99%; NaCl >99%; Phosphate-buffered saline tablets (PBS); Pentane >99%; Hexane >98.5%; Toluene >99.5%; Acetone >99.5% were purchased from Fisher Scientific; Durapore PVDF membrane (approximately 0.22 μm pore size, approximately 47 mm diameter) was purchased from Millipore. Co., Ltd.; The deionized water used in this method, i.e., DI water, comes from Milli-Q Advantage A10, and the milk is purchased from the local market;

[0042] Step 2, Synthesis of sulfobetaine silane, i.e., SBSi:

[0043] Based on previous research, SBSi was synthesized, with references: M. Litt, T. Matsuda, SILOXANEZWITTERIONS-SYNTHESIS AND SURFACE PROPERTIES OF CROSSLINKED POLYMERS, Journal of Applied Polymer Science 19(5)(1975)1221-1225 and SBYeh, CSChen, WYChen, CJHuang, Modification of Silicon Elastomer with Zwitterionic Silane for Durable Antifouling Properties, Langmuir 30(38)(2014)11386-11393. 5g of DMASi and 3g of 1,3-propane sulfone were dissolved in 25mL of anhydrous acetone and reacted under nitrogen at room temperature for 6h. The mixture was then filtered to produce a white solid product. The product was then washed with anhydrous acetone and dried under vacuum.

[0044] Step 3, Preparation of silane / TA coatings with different compositions:

[0045] First, the substrate surfaces (PVDF film, silicon wafer, QCM sensor, AFM probe) were repeatedly washed with alternating ethanol and water, followed by ultrasonic treatment in a 50 / 50 volume fraction water / ethanol mixture for 15 minutes. Then, they were placed in a UV / ozone cleaner for 15 minutes before use. For the preparation of the APZWF / TA coated substrate, a 50 / 50 volume fraction Tris-HCl solution (pH 8.5 solution / ethanol solution) was first prepared. Subsequently, different concentrations of 3-aminopropyltriethoxysilane (APTES), sulfobetaine silane (SBSi), and 1H,1H,2H,2H perfluorodecyltriethoxysilane were added. Oxysilane, namely FAS-17, was shaken on a shaker at 300 rpm for 10 minutes; then 2 mg / mL of tannic acid, namely TA, was added, and the mixture was shaken on a shaker at 300 rpm for 10 minutes; finally, the substrate material was added, and the mixture was shaken on a shaker at 100 rpm for 8 hours, i.e., coating deposition was completed at room temperature. The modified surface was then thoroughly rinsed with water and ethanol to remove impurities, and dried with nitrogen to obtain the APZWF / TA coated substrate; AP / TA coated substrates can be manufactured using the same method, including those without SBSi and FAS-17, and APZW / TA coated substrates without FAS-17.

[0046] Step 4, Material Characterization:

[0047] The surface chemical properties of the prepared coatings were analyzed using X-ray photoelectron spectroscopy (XPS) on an AXIS Ultra (Kratos Analytical) microscope. The hydrophilicity and hydrophobicity of the prepared coatings were determined using a contact angle goniometer. The surface morphology of the prepared coatings was characterized using atomic force microscopy (AFM) in air in tapping mode. The variations in surface morphology and elemental distribution of different coatings were characterized using a Zeiss Sigma 300VP-FESEM field emission scanning electron microscope and energy-dispersive X-ray spectroscopy (EDS).

[0048] Step 5, Surface force measurement:

[0049] AFM surface force measurements were performed using the Asylum Research MFP-3D. Silica microsphere probes were prepared by attaching silica microspheres to a tipless AFM cantilever beam using a two-component epoxy resin adhesive. The prepared silica probes were then placed in a UV / ozone cleaner for 15 minutes. During the surface force measurement experiment, the silica microsphere probes coated with AP / TA, APZW / TA, and APZWF / TA, along with the silicon surface, were immersed in a solution containing 10 mM TA. (Reference: JL Hutter, J. Bechhoefer, CALIBRATION OF ATOMIC-FORCE MICROSCOPE TIPS, Review of Scientific Instruments 64(7)(1993)1868-1873.34). Surface force was measured by driving the silica probes to approach the silicon surface below at a fixed speed of lum / s. Subsequently, the interaction force was determined using Hooke's law based on the stiffness coefficient of the AFM probe. (Reference: HJ Butt, B. Cappella, M. Kappl, Force measurements) with the atomic force microscope:Technique,interpretation and applications,SurfaceScience Reports 59(1-6)(2005)1-152;

[0050] Step 6, Evaluation of the anti-fouling performance of the coating surface:

[0051] The anti-fouling properties of the coating were determined by measuring the adsorbed mass of dirt on a silica sensor chip covered with an APZWF / TA coating in real time using a quartz crystal microbalance (QCM). Based on the frequency changes detected by the QCM, the mass change on the silica sensor chip due to dirt adsorption was calculated using the Sauerbrey equation.

[0052]

[0053] Where Δm is the mass change on the sensor, Δf is the frequency change of the sensor (Hz), and C is 17.7 ng Hz. - 1 cm -2 The constant is n, where n is the number of overtones;

[0054] The antifouling performance of the APZWF / TA coating was determined using O-PTIR (non-contact submicron visible probe infrared spectroscopy), a photographic thermograph by Photothermal Spectroscopy Corp., CA. A 20% milk solution was used as a model for biological contaminants, and O-PTIR spectroscopy revealed a characteristic peak at 1650 cm⁻¹. -1 Then, by setting the IR wavelength to its corresponding peak, the surface coverage of the milk stain sample was imaged at a resolution of 500 nm using an IR microscope. The antifouling performance of the coating surface was described by the change in the area distribution ratio of surface contaminants using ImageJ statistics.

[0055] Step 7, Membrane separation performance test of oil-in-water emulsion:

[0056] The separation performance of an APZWF / TA-coated PVDF membrane was determined by vacuum filtration separation of an oil-in-water emulsion containing 1 wt% toluene, pentane, and hexane, and 20 ppm SDS (O / W emulsion). The emulsion was prepared using a T-18 Ultra Turrax homogenizer with stirring at 15,000 rpm for 10 minutes. The size distribution of the prepared emulsion was characterized by dynamic light scattering (DLS) using a Zetasizer Nano ZSP. During the oil-water separation test, the membrane was immobilized in a dead-end filtration device, and the permeate flux through the membrane, J, was calculated using the following formula:

[0057]

[0058] Where ΔV is the volume of filtrate passing through the membrane during the filtration duration, S is the effective membrane area, and ΔP is the pressure difference between ambient pressure and vacuum pressure. The filtrate is then collected and characterized again using DLS.

[0059] In this embodiment, in step 7, in order to evaluate the membrane's anti-biofouling properties during O / W emulsion separation, the change in water flux through the membrane after O / W emulsion separation with added BSA and HA is measured and recorded in real time after each cycle. After each cycle of emulsion separation, the membrane is thoroughly washed before starting the next cycle.

[0060] Results and discussion

[0061] 1.1. Synthesis and Characterization

[0062] The APZWF / TA coating was synthesized using a simple one-pot self-assembly method, such as... Figure 1 As shown in ab. First, 3-aminopropyltriethoxysilane (APTES), sulfobetaine silane (SBSi), and 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-17) are reacted under hydration conditions to form hydrated silanes via a co-hydration reaction. The organic substituents of the hydrated silanes generate long-chain molecules containing multiple amino groups. Simultaneously, in a mild alkaline environment, tannic acid (TA) is oxidized to dopaquinone. Dopaquinone is a highly reactive oxidized phenolic compound that can undergo Schiff base reactions or Michael addition reactions with the amino groups in the hydrated silanes, further promoting coating formation. This method simplifies the synthesis steps, facilitating the preparation of APZWF / TA coatings with good performance. Reference: SHWu, KGYan, BLHe, Y.Wang, SHXue, SJLiu, Q.Ye, F.Zhou, Preparation of tannic acid based zwitterionic polymer functionalized coating on glass surface for antibacterial and antifouling applications, Progress in Organic Coatings 194 (2024). This reaction can form nanostructured coatings on hydrophilic surfaces, i.e., silicon wafers, and hydrophobic surfaces, i.e., PVDF films, while also firmly anchoring zwitterionic and low surface functional group components to the material surface.

[0063] The chemical composition and chemical bonding state of the coating were determined using X-ray photoelectron spectroscopy (XPS) to verify the above-mentioned reaction mechanism. Figure 2As shown in Figure c, the silicon wafers coated with AP / TA, APZW / TA, and APZWF / TA all exhibited peaks for carbon (C), nitrogen (N), and oxygen (O) elements in XPS scans. In the spectrum of the APZW / TA coating, an additional new peak appeared at 169 eV, corresponding to the S2p3 / 2 orbital in sulfobetaine silane (SBSi), indicating successful SBSi incorporation into the coating. Furthermore, in the spectrum of the APZWF / TA coating, characteristic peaks of perfluorocarbon (CF) introduced by perfluorodecyltriethoxysilane (FAS-17) were observed, typically appearing at approximately 287 eV and 290 eV. The appearance of these peaks further confirms the presence of FAS-17 in the coating. Reference: SBYeh, CSChen, WYChen, CJHuang, Modification of Silicon Elastomer with Zwitterionic Silane for Durable Antifouling Properties, Langmuir 30(38)(2014)11386-11393. In the X-ray photoelectron spectroscopy (XPS) of the APZWF / TA coating surface, a new peak was observed at 690 eV, which was attributed to the F1s signal, further confirming the presence of the perfluorinated compound FAS-17. Furthermore, the high-resolution C1s spectra and their fitted peaks of the AP / TA, APZW / TA, and APZWF / TA coatings are shown below. Figure 2As shown in df. All three spectra show distinct peaks at 284.8 eV, 286.0 eV, and 288.5 eV, corresponding to the CC, CO / CN, and C=O bonds, respectively. The peak values ​​of CN and C=O are attributed to the presence of APTES and TA, indicating that these components are successfully bonded in the coating. References: RHBian, Y.Zhu, Y.Lyu, YHLiu, JJLi, C.Li, JZLi, Bioinspired 'phenol-amine' cross-linking and mineral reinforcement enable strong, tough, and formaldehyde-free tannic acid-based adhesives, Journal of Cleaner Production 472 (2024); and GDZeng, K.Li, Y.Zhou, TZWang, YMDong, J.Luo, XXZhan, JZLi, Natural organic-inorganic hybrid structure enabled greenbiomass adhesive with desirable strength, toughness and mildew resistance, International Journal of Biological Macromolecules 236 (2023). Figure 2 In d, additional peaks appear at 292 and 293 eV, corresponding to CF and CF2, respectively. (Reference: BHPark, MHLee, SBKim, YMJo, Evaluation of the surface properties of PTFE foam coating filter media using XPS and contact angle measurements, Applied Surface Science 257(8)(2011)3709-3716). This indicates that all reactants, including APTES, SBSi, FAS-17, and TA, were successfully coated onto the surface. After the addition of FAS-17, the proportion of C-C bonds decreased significantly, and CF and CF2 peaks appeared simultaneously, indicating that FAS-17 can regulate the Schiff base / Michael addition reaction between APTES and TA.

[0064] Because SBSi is hydrophilic and FAS-17 is hydrophobic, their ratio in the coating solution significantly affects the wettability of the coating surface. Optimal reaction conditions for controlling coating formation were determined by adjusting the concentrations of SBSi and FAS-17. Water contact angle measurements on silicon substrates showed that the hydrophilicity of the coating improved with increasing SBSi concentration. Figure 2 The decrease in contact angle is shown in e. Conversely, with increasing FAS-17 concentration, the hydrophobicity of the coating surface increases, as... Figure 2 The increase in contact angle is shown in f. Experiments determined that the optimal concentrations of SBSi and FAS-17 are 2 mg / mL and 0.5 mg / mL, respectively. This is because the zwitterionic portion of SBSi can form a strong hydration layer, while the fluoride groups of FAS-17 have low surface energy. The synergistic effect of the two is expected to endow the coating surface with higher hydrophilicity and excellent wetting properties. In summary, by optimizing the concentrations of SBSi and FAS-17, the surface wettability of the APZWF / TA coating can be effectively controlled to achieve the desired hydrophilic or hydrophobic properties. This provides an important basis for optimizing the performance of the coating in different application scenarios.

[0065] 1.2. Surface Force Measurement

[0066] To evaluate the regulatory effects of zwitterionic SBSi and fluorinated FAS-17 on the reactivity of APTES with TA, atomic force microscopy (AFM) colloidal probe technology was used to quantitatively study the interaction forces of different silane components (AP / TA, APZW / TA, and APZWF / TA) during the assembly process. Figure 2 As shown in a-2c. In the experiment, after coating the silica probe and silicon substrate with AP / TA, APZW / TA, and APZWF / TA respectively, the interaction force between the probe and the substrate was measured in a 10 mM TA solution. The results showed that the AP / TA system containing APTES and TA exhibited a large adhesion force (approximately 0.78 nN) during the separation process. This was mainly attributed to the Schiff base / Michael addition reaction between the amino groups in APTES and the catechol groups in TA, and the AFM morphology diagram ( Figure 3 a2) shows that TA and APTES formed large aggregates due to uncontrolled reactions. The adhesion of the APZW / TA system after the introduction of zwitterionic SBSi decreased to approximately 0.48 nN. This is because the zwitterionic groups increased the hydration layer thickness and enhanced the steric hindrance effect. Simultaneously, the sulfonate groups further inhibited the reaction between APTES and TA by repelling negatively charged TA molecules. (AFM morphology diagram) Figure 3b2) also showed fewer and smaller aggregates, indicating a more controllable reaction. Further introduction of the fluorinated FAS-17-containing APZWF / TA system further reduced the adhesion to approximately 0.3 nN. This is because the low surface energy of the fluorine chain and its steric hindrance weaken the interaction between the coating surfaces. Simultaneously, the fluorine groups reduced the coating's affinity for TA molecules, thereby further inhibiting the reaction between APTES and TA. The AFM morphology diagram ( Figure 3 c2) shows a uniform coating. Combined AFM colloidal probe measurements and morphological image analysis results demonstrate that the reaction between APTES and TA was successfully regulated by introducing zwitterions and fluorinated groups. This not only facilitates the formation of a controllable, smooth, and uniform APZWF / TA coating on the hydrophilic silicon surface, but also suggests that the introduction of these groups can further regulate and enhance the wettability of the coating surface, which will be systematically analyzed and discussed in subsequent sections.

[0067] 1.3. Antifouling performance test of surface coating

[0068] The APZWF / TA coating not only enhances the surface's hydrophilicity through zwitterionic groups, forming a surface hydration layer to prevent contaminant adhesion, but also improves its fouling release capacity through the introduction of fluorine groups. To evaluate the antifouling performance of different coating compositions, OPTIR tests were performed on bare silicon wafer substrates and surfaces coated with AP / TA, APZW / TA, and APZWF / TA after milk contamination. Figure 4 As shown in the diagram, a large amount of milk stains adhered to the bare silicon substrate, while the AP / TA, APZW / TA, and APZWF / TA coatings significantly reduced the amount of milk stains adhering to varying degrees. Figure 4 b summarizes the dirt coverage on different substrates: the AP / TA coating reduced the coverage from 36.81% on the bare substrate to 16.91%; the APZW / TA coating further reduced the dirt coverage to 7.70%, mainly attributed to the enhanced hydrophilicity of the zwitterionic groups in SBSi, which form a hydration layer on the coating surface, acting as a physical barrier and effectively reducing dirt adhesion to the substrate. Furthermore, the APZWF / TA coated surface exhibited the lowest milk stain coverage, at only 4.25%. This excellent anti-fouling performance is attributed to the fluorinated groups present on the APZWF / TA surface, whose inherently low surface energy facilitates dirt separation from the surface, thus significantly improving the coating's dirt release capability.

[0069] In addition to using milk as a model contaminant for biofluids, the adhesion of APZWF / TA coatings to biomolecules (such as BSA) was quantitatively measured using quartz crystal microbalance (QCM) technology. Figure 4As shown in Figure c, the bare silica sensor exhibited a significant frequency decrease (47.6 Hz) after BSA adsorption, indicating substantial adsorption of contaminants. In contrast, the APZWF / TA-coated sensor showed only a slight frequency decrease (9.3 Hz), demonstrating a significantly reduced amount of contaminant adsorption and showcasing its superior anti-adhesion properties. Furthermore, after BSA adsorption on the bare silica sensor, rinsing with PBS buffer removed only 4.7% of the contaminant, while on the APZWF / TA-coated sensor, 26% of the contaminant was removed under the same conditions, demonstrating excellent contaminant release characteristics.

[0070] 1.4. Preparation of surface-functionalized PVDF films

[0071] Given the broad adhesion of TA to various surfaces, we further deposited an APZWF / TA nanocoating on the surface of a PVDF film. The morphology of the bare PVDF film, AP / TA, APZW / TA, and APZWF / TA coated PVDF film was observed using scanning electron microscopy (SEM) to explore the formation mechanism of different coating components. The unmodified PVDF film showed a highly porous structure and a smooth surface in the SEM images. When the PVDF film was immersed in a mixed solution of APTES and TA, a large number of nanospheres formed on the surface, indicating the success of the AP / TA coating. The formation of these nanospheres is attributed to the reaction of APTES hydration products to generate amino-rich long-chain molecules, which subsequently react with TA oxidation products via a Schiff base / Michael addition reaction. However, the reaction between APTES and TA was rapid and uncontrolled, resulting in large and unevenly distributed nanospheres in the coating.

[0072] After adding zwitterionic silane SBSi to the coating solution, the morphology of the APZW / TA-coated PVDF film was similar to that of the AP / TA-coated film, indicating that the regulatory effect of SBSi on the APTES-TA reaction on the hydrophobic PVDF surface is not as significant as that on the hydrophilic silicon substrate (see...). Figure 3(b2). However, upon further introduction of the fluorinated silane FAS-17, the surface of the APZWF / TA-coated PVDF film was covered with uniformly distributed micro-nanospheres, demonstrating the excellent performance of FAS-17 in regulating the reaction between APTES and TA. Energy-dispersive X-ray spectroscopy (EDX) analysis showed that the carbon (C), oxygen (O), nitrogen (N), and sulfur (S) elements in the APZWF / TA-coated PVDF film were uniformly distributed, reflecting the uniform distribution of the coating components. After coating with APZW / TA, the mass content of sulfur increased from 0 to 0.49 wt%, attributed to the introduction of SBSi; while between the APZW / TA and APZWF / TA coatings, the mass fraction of fluorine increased from 41.07 wt% to 47.14 wt%, attributed to the incorporation of FAS-17. These results demonstrate that the APZWF / TA coating uniformly covers the PVDF film.

[0073] 1.5. Surface wettability test of membrane material

[0074] To investigate the effect of APZWF / TA coating on the wetting properties of polyvinylidene fluoride (PVDF) films, a series of contact angle experiments were conducted. The untreated PVDF film exhibited high hydrophobicity, such as... Figure 5 The time-dependent water contact angle measurement results shown in Figure a indicate that the contact angle remained consistently around 110 degrees. In contrast, the contact angle of the APZWF / TA-coated PVDF membrane rapidly decreased to 60 degrees in the initial stage and further decreased to approximately 30 degrees within one minute, indicating that the originally hydrophobic membrane successfully transformed into a hydrophilic membrane. This enhanced hydrophilicity not only endows the membrane with excellent underwater oleophobic properties, but also, after being combined with the low surface energy FAS-17, the APZWF / TA-coated PVDF membrane exhibits significant resistance to oil fouling and contamination. Figure 5As shown in b, the contact angle of the oil droplets underwater is greater than 160 degrees over a wide pH range, demonstrating high stability under both acidic and alkaline conditions. The excellent tolerance of APZWF / TA coating to acidic and alkaline environments is mainly attributed to: First, the zwitterionic groups in SBSi are insensitive to pH changes, thus maintaining the integrity of the hydration layer under different pH conditions. Reference: N. Chen, CY Zhang, XY Dong, Y. Sun, Fabrication and characterization of epoxylated zwitterionic copolymer-grafted silica nanoparticle as a new support for lipase immobilization, Chinese Journal of Chemical Engineering 28(4)(2020)1129-1135; Second, the fluorine chain of FSA-17 is also very stable under harsh pH conditions, maintaining the low surface energy of the coating surface. Reference: DY Zhou, SY Cai, HY Sun, GS Zhong, H. Zhang, DZ Sun, FY Su, MY Deng, YQ Tian, ​​Diatom frustules based dissolved oxygen sensor with superhydrophobic surface, Sensors and Actuators B-Chemical 371(2022). These properties collectively endow the APZWF / TA coating with excellent wetting control capabilities, enabling it to exhibit superior antifouling performance in a variety of application environments.

[0075] The anti-oil adhesion performance of the membrane was then evaluated through dynamic underwater oil droplet adhesion experiments. During the tests, the adhesion of oil droplets to the membrane surface was characterized by manipulating the droplets to approach, compress, and detach from the membrane surface. When an oil droplet was pressed onto the bare PVDF membrane, it immediately adhered to the membrane surface and remained attached even when the needle was retracted. Figure 5 As shown in c. In contrast, when oil droplets are pressed onto the APZWF / TA coated film, the oil droplets can easily separate from the film surface without leaving any residual oil residue, as shown in c. Figure 5As shown in d, bare PVDF membranes possess low surface energy due to the abundant fluorine atoms in their polymer chains. However, oil droplets, inherently hydrophobic and lacking a hydration layer, still adhere to the membrane surface. The APZWF / TA coating significantly enhances the hydrophilicity of the PVDF membrane through an SBSi-induced hydration layer, while maintaining the low surface energy imparted by FAS-17. This coating not only exhibits low oil adhesion underwater but also demonstrates excellent anti-adsorption properties against various organic fouling substances, giving APZWF / TA-coated PVDF membranes broad application prospects in oil / water separation.

[0076] 1.6. Testing of the water-in-oil emulsion separation performance of membrane materials

[0077] Figure 7 A schematic diagram of a vacuum filtration apparatus is shown for evaluating the permeation flux of PVDF membranes with different coatings: AP / TA, APZW / TA, and APZWF / TA. Due to the hydrophobic nature of the membrane, the water flux of a bare PVDF membrane is low. However, after treatment with APTES and TA, the membrane surface is coated with nanospheres rich in hydrophilic groups, significantly enhancing the membrane's hydrophilicity and enabling a pure water permeation flux of approximately 4600 L / m³. -2 h-1bar - 1 (see) Figure 7 d). With the introduction of zwitterionic molecules, the hydrophilicity of the membrane is further improved, and the water flux increases to approximately 5700 L / m². -2 h-1bar -1 The increase in water flux is mainly attributed to the presence of additional hydrophilic groups on the membrane surface, which effectively reduces the permeation resistance of water molecules. Reference: KMKim, SHWoo, JJSLee, HSPark, J.Park, BRMin, Improved Permeate Flux of PVDF Ultrafiltration Membrane Containing PVDF-g-PHEA Synthesized via ATRP, Applied Sciences-Basel 5(4)(2015)1992-2008. Adding fluorine atoms to the coating leads to a decrease in membrane surface energy and an increase in hydrophobicity, resulting in a slight decrease in pure water flux to approximately 5400 Lm. -2 h-1bar -1 .like Figure 7 As shown in Figure e, the APZWF / TA coated membrane exhibits stable permeability under various water conditions (including high salinity 1M NaCl, acidic pH 3, and alkaline pH 9), indicating its excellent stability and consistency in treating actual wastewater. In the separation experiment of the oil-in-water (O / W) emulsion, the initial emulsion was milky white and opaque, with a hydrodynamic droplet radius of approximately 200 nm. Figure 7 b). After membrane filtration, the emulsion becomes clear and transparent, and the particle size distribution is reduced to approximately 3 nm. Figure 7 c) The presence of residual SDS micelles in the filtrate indicates that oil droplets have been successfully removed from the O / W emulsion. When using pentane, hexane, and toluene to separate different types of emulsions, the APZW / TA and APZWF / TA coated membranes exhibited approximately 3000 μm. - 2h-1bar - The AP / TA coated membrane has a higher water flux of 1, while the water flux of the AP / TA coated membrane is approximately 2000 Lm. - 2h-1bar - 1 (see) Figure 7 f). This increase in permeation flux is attributed to the introduction of zwitterionic molecules, which increases the membrane's hydrophilicity, thereby reducing the transport resistance of the naturally hydrophobic membrane. Furthermore, the membrane not only effectively removes oil but also prevents biofouling such as BSA and HA (…). Figure 7 g) Adhesion on the membrane surface: In emulsion systems containing BSA or HA, the permeation flux of the APZWF / TA coated membrane decreased slightly to approximately 2700 and 2600 μm, respectively. - 2h-1bar - 1. However, it can achieve efficient and effective separation of oil-water emulsions. In summary, by optimizing the ratio of silane and fluorinated components, the APZWF / TA coating significantly improves the hydrophilicity and antifouling properties of the PVDF membrane, while maintaining a stable permeation flux under different water quality conditions. These excellent properties demonstrate the significant potential of APZWF / TA-coated PVDF membranes in practical oil / water separation applications.

[0078] 1.7. Oil resistance test of membrane materials

[0079] When using membrane filtration technology to separate O / W emulsions, the accumulation of contaminants such as oil droplets in the aqueous phase on the membrane surface can clog the membrane's porous structure and affect its permeation flux. Therefore, this paper conducts cyclic filtration tests on the durability of APZWF / TA coated PVDF membranes to evaluate their performance stability in the process of separating O / W emulsions. Figure 7 This paper presents the permeation flux performance of the APZWF / TA coated PVDF membrane in ten cycles of O / W emulsion separation experiments. The results show that the coating maintained a relatively stable permeation flux during continuous oil-water separation, demonstrating excellent stability.

[0080] The cycling separation performance of PVDF membranes with different coatings was evaluated using an O / W emulsion containing BSA fouling (see [link to evaluation]). Figure 7(b) During the first oil-water separation cycle, the permeate flux of the AP / TA, APZW / TA, and APZWF / TA coated PVDF membranes gradually decreased to approximately 27%, 35%, and 46% of their initial permeate flux, respectively. This sharp decrease in permeate flux was mainly attributed to BSA adsorption on the membrane surface during filtration, which blocked the membrane pores and hindered water molecule transport. In contrast, the APZWF / TA coated PVDF membrane showed the smallest decrease in permeate flux, reflecting its higher resistance to oil droplet and BSA fouling. After water rinsing, the AP / TA, APZW / TA, and APZWF / TA coated PVDF membranes were able to recover 81%, 88%, and 96% of their initial water flux, respectively. In particular, the APZWF / TA composite membrane exhibited a higher permeate flux recovery rate, indicating its good surface release performance of contaminants, which is mainly attributed to the low surface energy characteristics brought about by the introduction of FAS-17. By the third cycle, the APZWF / TA-coated PVDF membrane still retained approximately 92% of the original water flux, indicating that the coating still has good recyclability and reusability even in the presence of protein contaminants such as BSA.

[0081] In addition to filtration tests on oil-in-water emulsions, this paper also uses a syringe to spray oil red O-stained toluene at high speed onto the surface of coated PVDF membranes to evaluate the resistance of different coatings to oil adhesion. Figure 7 As shown in Figure c, the AP / TA-coated PVDF membrane, due to its hydrophilicity, can deflect most oil droplets, but some droplets are still eventually contaminated by the jet and remain on the membrane surface. In contrast, the APZW / TA and APZWF / TA-coated PVDF membranes can completely repel oil droplets from the jet (see Figure c). Figure 7 d~ Figure 7 e). This improvement in oil-repellent properties is attributed to the introduction of zwitterionic molecules, which increases the hydrophilicity of the coating, thereby creating a robust hydration layer above the film surface that effectively repels the adhesion of oil droplets.

[0082] In summary, inspired by the mussel adhesion mechanism, this method successfully prepared a self-assembled coating with excellent antifouling properties through the co-hydration reaction of APTES, SBSi, and FAS-17, combined with the Schiffbase / Michael addition reaction between APTES and TA. Water contact angle testing and atomic force microscopy (AFM) morphology analysis showed that SBSi and FAS-17 played a key role in regulating the coating's wettability and effectively modulated the chemical reaction between APTES and TA, thus forming a uniform APZWF / TA coating on the silicon substrate and PVDF film surface. This coating exhibited excellent resistance to biofluid contamination, biomolecule adsorption, and oil droplet adhesion. Its superior antifouling performance mainly stemmed from the following three aspects: First, the controllable reaction between APTES and TA formed a uniform coating and provided abundant anchoring sites for additional functional groups; second, the introduction of zwitterionic SBSi formed a stable hydration layer, effectively preventing dirt adsorption; and finally, the low surface energy of the fluorinated FAS-17 facilitated the detachment of adsorbed dirt. Furthermore, the APZWF / TA coated PVDF membrane exhibits a viscosity exceeding 5700 L / m². - 2h-1bar - The ultra-high water flux and efficient oil-in-water emulsion separation performance of 1 further demonstrate its excellent stability and antifouling ability in complex environments. This coating strategy not only significantly improves the hydrophilicity and antifouling properties of the PVDF membrane, but also maintains a stable permeation flux under different water quality conditions, showcasing its broad application prospects in surface water treatment and oil / water separation in engineering and environmental applications. It also provides strong theoretical basis and technical support for the development of multifunctional novel coatings.

[0083] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0084] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for treating mussel-type functional antifouling coatings using triple silane co-hydration regulation, characterized in that: The method includes the following steps: Step 1, Materials: Tannic acid (TA), >99.5%, 3-aminopropyltriethoxysilane (APTES), >98%, 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-17), >97%, ethanol >99.5%, bovine serum albumin (BSA), >98%, humic acid (HA), >98%, pepsin >98.0%, hemoglobin >98%, Oil Red O, sodium dodecyl sulfate (SDS), >99%, NaCl >99%, phosphate-buffered saline tablets (PBS), pentane >99%, hexane >98.5%, toluene >99.5%, acetone >99.5% were purchased from Fisher Scientific; Durapore The PVDF membrane, with a pore size of approximately 0.22 μm and a diameter of approximately 47 mm, was purchased from Millipore Co. Ltd.; the deionized water used in this method, i.e., DI water, was from Milli-Q Advantage A10, and the milk was purchased from the local market. Step 2, Synthesis of sulfobetaine silane, i.e., SBSi: According to previous studies, SBSi was synthesized by dissolving 5g DMASi and 3g 1,3-propane sulfone in 25mL of anhydrous acetone and reacting with nitrogen at room temperature for 6h. The mixture was then filtered to produce a white solid product, which was then washed with anhydrous acetone and dried under vacuum. Step 3, Preparation of silane / TA coatings with different compositions: First, the substrate surface, including the PVDF film, silicon wafer, QCM sensor, and AFM probe, was repeatedly washed with alternating ethanol and water. It was then ultrasonically treated for 15 minutes in a 50 / 50 volume fraction water / ethanol mixture, followed by 15 minutes in a UV / ozone cleaner before use. For the preparation of the APZWF / TA coated substrate, a 50 / 50 volume fraction Tris-HCl solution (pH 8.5) was first prepared, followed by the addition of different concentrations of 3-aminopropyltriethoxysilane (APTES), sulfobetaine silane (SBSi), and 1H,1H,2H,2H perfluorodecyltriethoxysilane. Oxysilane, namely FAS-17, was shaken on a shaker at 300 rpm for 10 minutes; then 2 mg / mL of tannic acid, namely TA, was added, and the mixture was shaken on a shaker at 300 rpm for 10 minutes; finally, the substrate material was added, and the mixture was shaken on a shaker at 100 rpm for 8 hours, i.e., coating deposition was completed at room temperature. The modified surface was then thoroughly rinsed with water and ethanol to remove impurities, and dried with nitrogen to obtain the APZWF / TA coated substrate; AP / TA coated substrates can be manufactured using the same method, including those without SBSi and FAS-17, and APZW / TA coated substrates without FAS-17. Step 4, Material Characterization: The surface chemical properties of the prepared coatings were analyzed using X-ray photoelectron spectroscopy (XPS) from AXISUltra (Kratos Analytical, UK). The hydrophilicity and hydrophobicity of the prepared coatings were determined using a contact angle goniometer. The surface morphology of the prepared coatings was characterized using atomic force microscopy (AFM) in air with tapping mode. The variations in surface morphology and elemental distribution of different coatings were characterized using a Zeiss Sigma 300VP-FESEM field emission scanning electron microscope and energy-dispersive X-ray spectroscopy (EDS). Step 5, Surface force measurement: AFM surface force measurements were performed using an Asylum Research MFP-3D. Silica microsphere probes were prepared by attaching silica microspheres to a tipless AFM cantilever beam using a two-component epoxy resin adhesive. The prepared silica probes were then placed in a UV / ozone cleaner for 15 minutes. During the surface force measurement experiment, the silica microsphere probes coated with AP / TA, APZW / TA, and APZWF / TA coatings, along with the silicon surface, were immersed in a solution containing 10 mMTA. Surface force tests were conducted by driving the silica probes close to the underlying silicon surface at a fixed speed of 1 μm / s. Subsequently, the interaction forces were determined using Hooke's law based on the stiffness coefficient of the AFM probes. Step 6, Evaluation of the anti-fouling performance of the coating surface: The anti-fouling properties of the coating were determined by measuring the adsorbed mass of dirt on a silica sensor chip covered with an APZWF / TA coating in real time using a quartz crystal microbalance (QCM). Based on the frequency changes detected by the QCM, the mass change on the silica sensor chip due to dirt adsorption was calculated using the Sauerbrey equation. Where Δm is the mass change on the sensor, Δf is the frequency change of the sensor (Hz), and C is 17.7 ngHz. -1 cm -2 The constant is n, where n is the number of overtones; The antifouling performance of the APZWF / TA coating was determined using O-PTIR (non-contact submicron visible probe infrared spectroscopy, mIRage, Photothermal Spectroscopy Corp., CA). A 20% milk solution was used as a model for biological contaminants. O-PTIR spectroscopy showed that the characteristic peak of milk was located at 1650 cm⁻¹. -1 Then, by setting the IR wavelength to its corresponding peak, the surface coverage of the milk stain sample was imaged at a resolution of 500 nm using an IR microscope. The antifouling performance of the coating surface was described by the change in the area distribution ratio of surface contaminants using ImageJ statistics. Step 7, Membrane separation performance test of oil-in-water emulsion: The separation performance of an APZWF / TA-coated PVDF membrane was determined by vacuum filtration separation of an oil-in-water emulsion containing 1 wt% toluene, pentane, and hexane, and 20 ppm SDS (O / W emulsion). The emulsion was prepared using a T-18 UltraTurrax homogenizer with stirring at 15,000 rpm for 10 minutes. The size distribution of the prepared emulsion was characterized by dynamic light scattering (DLS) using a Zetasizer NanoZSP. During the oil-water separation test, the membrane was immobilized in a dead-end filtration device, and the permeate flux through the membrane, J, was calculated using the following formula: Where ΔV is the volume of filtrate passing through the membrane during the filtration duration, S is the effective membrane area, and ΔP is the pressure difference between ambient pressure and vacuum pressure. The filtrate is then collected and characterized again using DLS.

2. The method for treating mussel-type functional antifouling coatings according to claim 1, characterized in that: In step 7, to evaluate the membrane’s anti-biofouling properties during O / W emulsion separation, the change in water flux through the membrane after O / W emulsion separation with added BSA and HA was measured and recorded in real time after each cycle. The membrane was thoroughly washed after each cycle of emulsion separation and before starting the next cycle.

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