A guanidino-camphor bifunctional synergistic antibacterial and anti-adhesion coating and a preparation method thereof

Abstract

The application discloses a guanidyl-borneol bifunctional synergistic antibacterial and anti-adhesion coating and a preparation method thereof. First, a guanidyl functionalized silane coupling agent (TMSPAEG) and a borneol functionalized silane coupling agent (BS) are synthesized, and then the addition reaction of isocyanate and secondary amine is used to covalently graft them into an isophorone diisocyanate (IPDI) capped polytetramethylene glycol (PTMEG) prepolymer system. Under the endogenous catalysis of guanidyl and high-temperature curing conditions, the system further undergoes a sol-gel reaction, a dense Si-O-Si three-dimensional crosslinking network is constructed, and thus a coating with excellent structural stability and mechanical properties is obtained. The preparation process is simple, the guanidyl antibacterial unit and the borneol anti-adhesion structure can be introduced on the surface of the coating at the same time, the limitation of the traditional single antibacterial mode is broken through, the synergistic effect of antibacterial and anti-adhesion is realized, and thus the long-term antibacterial and anti-biological pollution performance of the coating is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of functional polymer materials and antibacterial coating technology, specifically to a guanidine-borneol bifunctional synergistic antibacterial and anti-adhesion coating and its preparation method. Background Technology

[0002] Antimicrobial surfaces have a wide range of practical applications, demonstrating significant value in numerous fields. For example, in the medical field, antimicrobial coatings used in medical supplies such as urinary catheters and wound dressings can effectively inhibit biofilm formation and reduce the risk of infection. In marine antifouling, antimicrobial materials coated on ship hulls can effectively reduce the adhesion of marine organisms, thereby reducing maintenance costs. In public environments, antimicrobial coatings can effectively reduce the spread of germs and improve public health safety in high-frequency contact areas such as elevator buttons and door handles. Currently, most antimicrobial surfaces still rely on sustained-release antimicrobial agents such as silver ions or antibiotics. These antimicrobial agents are prone to migration and diffusion during use, leading to a rapid decrease in activity or even inactivation, making it difficult to achieve long-term antimicrobial effects. More importantly, some released antimicrobial agents may have potential toxicity to human cells and the ecological environment, failing to meet current requirements for biosafety and sustainability. Therefore, developing non-release, structurally stable, broad-spectrum, and durable antimicrobial strategies has become a key direction for the design of next-generation antimicrobial coatings.

[0003] In recent years, guanidine-functionalized materials have seen particularly active applications in the field of antibacterial coatings. Multiple studies have confirmed that guanidine compounds exhibit excellent inhibitory and bactericidal abilities against common clinical pathogens such as Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. By introducing guanidine groups into the polymer backbone and side chains, non-release, long-lasting contact bactericidal surfaces can be achieved.

[0004] In addition to antibacterial capabilities, enhancing the coating's ability to inhibit bacterial adhesion is also a key aspect of constructing high-performance antibacterial coatings. In the process of bacterial contamination, initial bacterial adhesion is the primary step leading to subsequent biofilm formation and infection transmission. Once bacteria successfully adhere to a material surface, they gradually secrete extracellular polymers, forming a firmly attached and highly drug-resistant biofilm structure that is extremely difficult to remove using conventional disinfection methods. Even in the presence of antibacterial agents, bacteria within the biofilm may still survive, leading to long-term infection and enhanced drug resistance. Studies have shown that surface microstructure, hydrophobicity, and steric hindrance play important regulatory roles in the early stages of bacterial adhesion. Introducing rigid hydrophobic groups can effectively increase surface steric hindrance, interfering with the close contact between bacteria and the surface, thereby reducing the initial adhesion rate. Borneol and its derivatives, due to their unique bicyclic rigid structure, hydrophobicity, and steric hindrance effect, have shown excellent performance in interfering with initial bacterial adhesion and have been widely used in recent years to develop anti-adhesion materials. However, it remains a significant challenge to efficiently and synergistically integrate anti-adhesion and contact sterilization mechanisms into the same coating system while simultaneously ensuring mechanical durability, substrate universality, and green, non-release properties (Athukoralalage SSA, Amiralian N. Dual-functional surface coatings integrating antimicrobial and antibiofouling mechanisms: from material design to application landscapes[J]. Materials Horizons, 2025, 12 (23), 9966-9993.).

[0005] Based on this, the present invention aims to provide a coating and its preparation method that efficiently and synergistically integrates anti-adhesion and contact sterilization mechanisms into the same coating system, while taking into account mechanical durability, substrate universality and green non-release characteristics. Summary of the Invention

[0006] To address the issues of limited antibacterial mechanisms and insufficient biofilm resistance in existing antibacterial coatings, the present invention aims to provide a guanidine-borneol bifunctional synergistic antibacterial and anti-adhesion coating and its preparation method.

[0007] The objective of this invention is achieved through the following technical solutions. This invention provides a guanidine-borneol bifunctional synergistic antibacterial and anti-adhesion coating, which is a PU-GM coating. x -BS yThe coating is composed of polyurethane prepolymer, guanidine functionalized silane coupling agent TMSPAEG and borneol functionalized silane coupling agent BS, wherein the polyurethane prepolymer is isophorone diisocyanate IPDI-terminated polytetrahydrofuran PTMEG prepolymer.

[0008] Preferably, the antibacterial bacteria are Escherichia coli or Staphylococcus aureus.

[0009] This invention also provides a method for preparing the above-mentioned guanidine-borneol bifunctional synergistic antibacterial and anti-adhesion coating, comprising the following steps: (1) Synthesis of polyurethane prepolymer: Polytetrahydrofuran (PTMEG) is dissolved in a solvent, heated, and isophorone diisocyanate (IPDI) and a catalyst are added to react and synthesize polyurethane prepolymer. (2) Synthesis of guanidinyl functionalized silane coupling agent TMSPAEG: Thiourea and iodomethane react to generate 2-methylisothiourea hydroiodide, and the product is purified by concentration and precipitation; then 2-methylisothiourea hydroiodide is reacted with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane AEAPTMS to synthesize guanidinyl functionalized silane coupling agent TMSPAEG. (3) Synthesis of borneol-functionalized silane coupling agent BS: Borneol-functionalized silane coupling agent BS is synthesized by reacting isoborneol acrylate BA and 3-aminopropyltrimethoxysilane APTMS. (4) Coating solution preparation and curing: BS and TMSPAEG are dissolved in ethanol and added to polyurethane prepolymer to react and obtain coating precursor solution; the coating precursor solution is drop-coated or spin-coated onto the surface of activated substrate and cured to obtain PU-GM x -BS y coating.

[0010] Preferably, the synthesis route of the polyurethane prepolymer is as follows:

[0011] Preferably, the synthetic route for the guanidinyl-functionalized silane coupling agent TMSPAEG is as follows:

[0012] Preferably, the synthetic route for the borneol-functionalized silane coupling agent BS is as follows:

[0013] Preferably, in step (1), the concentration of IPDI is 0.14-0.16 mol / L and the concentration of PTMEG is 0.04-0.06 mol / L.

[0014] More preferably, in step (1), the concentration of IPDI is 0.15 mol / L and the concentration of PTMEG is 0.05 mol / L.

[0015] Preferably, in step (1), the solvent is tetrahydrofuran (THF) and the catalyst is dibutyltin dilaurate (DBTDL).

[0016] Preferably, in step (1), the heating is to 70-90°C and the reaction time is 1-3h.

[0017] More preferably, in step (1), the heating is to 80°C and the reaction time is 2 hours.

[0018] Preferably, in step (2), the reaction conditions for thiourea and iodomethane are to be protected from light and the reaction time is 10-14 h.

[0019] More preferably, in step (2), the reaction time of thiourea and iodomethane is 12h.

[0020] Preferably, in step (2), the reaction time of 2-methylisothiourea hydroiodide with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane AEAPTMS is 4-8 h.

[0021] More preferably, in step (2), the reaction time of 2-methylisothiourea hydroiodide with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane AEAPTMS is 6 h.

[0022] Preferably, in step (3), the molar ratio of isoborneol acrylate BA to 3-aminopropyltrimethoxysilane APTMS is 1:0.9-1:1.1.

[0023] More preferably, in step (3), the molar ratio of isoborneol acrylate BA to 3-aminopropyltrimethoxysilane APTMS is 1:1.

[0024] Preferably, in step (3), the reaction temperature is 60-70°C and the reaction time is 20-28h.

[0025] More preferably, in step (3), the reaction temperature is 65°C and the reaction time is 24h.

[0026] Preferably, in step (4), the concentrations of BS and TMSPAEG dissolved in ethanol are both 0-0.6 mol / L.

[0027] More preferably, in step (4), the concentrations of BS and TMSPAEG dissolved in ethanol are both 0.3 mol / L.

[0028] Preferably, in step (4), the reaction temperature is 70-90°C and the reaction time is 1-3h.

[0029] More preferably, in step (4), the reaction temperature is 80°C and the reaction time is 2h.

[0030] Preferably, in step (4), the substrate surface is activated using a piranha solution.

[0031] Preferably, in step (4), the curing conditions are: first, high temperature curing at 100-140°C for 1-3 hours, and then room temperature curing for 20-28 hours.

[0032] More preferably, in step (4), the curing conditions are: first, high temperature curing at 120°C for 2 hours, and then room temperature curing for 24 hours.

[0033] This invention provides a method for preparing a guanidine-borneol bifunctional synergistic antibacterial and anti-adhesion coating. By grafting functional guanidine and borneol onto a silane coupling agent, reactive siloxanes and secondary amines are obtained. Subsequently, isocyanate groups in an IPDI-terminated PTMEG prepolymer synthesized via the reaction of IPDI and PTMEG are incorporated into the polyurethane system, allowing the functional structure to be grafted onto the polyurethane system. Finally, under the intrinsic catalytic action of the guanidine and high-temperature curing conditions, the system undergoes a sol-gel reaction to construct a dense Si-O-Si three-dimensional cross-linked network, thereby obtaining a PU-GM coating with excellent structural stability and mechanical properties. x -BS y coating.

[0034] Compared with existing technologies, the present invention has the following advantages: (1) The guanidine-borneol dual-function synergistic antibacterial and anti-adhesion coating provided by the present invention achieves excellent comprehensive performance with both bactericidal rate and anti-adhesion rate ≥92% through the synergistic effect of guanidine strong cationic contact bactericidal and borneol rigid hydrophobic impedance adhesion, which is significantly better than single-mechanism coatings. (2) The present invention utilizes the endogenous base catalysis of guanidine group and the high temperature promoted sol-gel reaction to construct a highly cross-linked Si-O-Si network, which endows the coating with excellent structural stability, mechanical strength and durability. (3) The present invention adopts a non-release coating design, which avoids the toxicity and environmental risks of traditional release antibacterial agents; at the same time, it has extremely high transparency (>99%) and ultra-low roughness, making it suitable for optically transparent substrates; (4) The preparation method provided by the present invention is mild and provides a new strategy for developing long-lasting, broad-spectrum, non-release antibacterial and antifouling coatings, which has broad application prospects in the fields of medical care, public health, and marine engineering. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the guanidine-borneol bifunctional synergistic antibacterial and anti-adhesion coating provided by the present invention.

[0036] Figure 2 The image shows the 1H NMR spectrum of TMSPAEG, a guanidinofunctionalized silane coupling agent prepared in Example 2.

[0037] Figure 3 The image shows the 1H NMR spectrum of the borneol-functionalized silane coupling agent BS prepared in Example 3.

[0038] Figure 4 PU-GM prepared in Example 10 x -BS y Infrared spectra of the coating, where (a) shows the components of the coating (PTMEG, IPDI, BS, TMSPAEG) and the coating itself (PU-GM). 0.5 -BS 0.5 (a) is the infrared spectrum of PU-GM, and (b) is the infrared spectrum of PU-GM. x -BS y Comparison of infrared spectra of coatings.

[0039] Figure 5 PU-GM prepared in Example 10 0.5 -BS 0.5 X-ray photoelectron spectrum of the coating.

[0040] Figure 6 PU-GM prepared in Example 10 x -BS y Transmittance and water contact angle diagrams of the coatings, where (a) shows PU-GM coatings with different TMSPAEG and BS contents. x -BS y The UV-Vis transmission spectrum of the coating, with a coating thickness of approximately 25 μm (illustration showing PU-GM). 0.5 -BS 0.5 (b) shows the school emblem on the back of the coated glass. x -BS y Contact angle on the coating.

[0041] Figure 7 PU-GM prepared in Example 10 x -BS y Surface morphology images of the coatings, where (a) shows ordinary glass and PU-GM. x -BS y SEM images of the coated glass substrate, (b) showing PU-GM 0.5 -BS 0.5 EDS elemental distribution on the coating surface, (c) is PU-GM x -BS y Two-dimensional atomic force microscope image of the coating surface.

[0042] Figure 8 PU-GM prepared in Example 10 x -BS y The mechanical properties of the coating are shown in the diagram, where (a) represents PU-GM. x -BS y The load-displacement curves of the coating, (b) for PU-GM x -BS y The hardness and elastic modulus of the coating, (c) is for PU-GM x -BS y Coating adhesion test curve, (d) is for PU-GM x -BS y The adhesion of the coating to the glass substrate.

[0043] Figure 9 PU-GM prepared in Example 10 x -BS y Antibacterial test diagram, where (a) is PU-GM x -BS y The coatings are respectively with E. coli. and S. aureus Plate counting images after 24 h of co-culture, (b) is PU-GM x -BS y Coatings E. coli Antibacterial properties . (c) is PU-GM x -BS y Coatings S. aureus Its antibacterial properties.

[0044] Figure 10 PU-GM prepared in Example 10 x -BS y Antibacterial adhesion experiment diagram, where (a) is E. coli. and S. aureus From PU-GM x -BS y Plate counting images after coating surface separation, (b) is PU-GM x -BS y Coatings E. coli. The anti-adhesion properties, (c) are those of PU-GM x -BS y Coatings S. The anti-adhesion properties of aureus. Detailed Implementation

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the embodiments described are only some representative embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0046] Figure 1 This is a schematic diagram of a guanidine-borneol bifunctional synergistic antibacterial and anti-adhesion coating. The diagram shows the chemical formula of the guanidine-borneol bifunctional synergistic antibacterial and anti-adhesion coating and its antibacterial and anti-adhesion effect after being drop-coated onto a substrate.

[0047] Example 1 Synthetic polyurethane prepolymer 300 mg of dry polytetrahydrofuran (PTMEG) (0.15 mmol) and 3 mL of ultra-dry tetrahydrofuran (THF) were added to a reaction flask filled with nitrogen. After heating to 80°C, 100 mg of isophorone diisocyanate (IPDI) (0.45 mmol) and 20 mg of dibutyltin dilaurate (DBTDL) were added. The mixture was stirred at this temperature for 2 h to obtain a polyurethane prepolymer.

[0048] Example 2 Synthetic polyurethane prepolymer 240 mg of dry polytetrahydrofuran (PTMEG) (0.12 mmol) and 3 mL of ultra-dry tetrahydrofuran (THF) were added to a reaction flask filled with nitrogen. After heating to 70°C, 93 mg of isophorone diisocyanate (IPDI) (0.42 mmol) and 20 mg of dibutyltin dilaurate (DBTDL) were added. The mixture was stirred at this temperature for 1 h to obtain a polyurethane prepolymer.

[0049] Example 3 Synthetic polyurethane prepolymer 360 mg of dry polytetrahydrofuran (PTMEG) (0.18 mmol) and 3 mL of ultra-dry tetrahydrofuran (THF) were added to a reaction flask filled with nitrogen. After heating to 90°C, 107 mg of isophorone diisocyanate (IPDI) (0.48 mmol) and 20 mg of dibutyltin dilaurate (DBTDL) were added. The mixture was stirred at this temperature for 3 h to obtain a polyurethane prepolymer.

[0050] Example 4 Synthetic guanidinyl functionalized silane coupling agent TMSPAEG 5.25 g of thiourea and 11.75 g of iodomethane were dissolved in a reaction flask containing 35 mL of ethanol and stirred at room temperature in the dark for 12 h. After the reaction was complete, the product was concentrated by rotary evaporation, then precipitated in ice-cold diethyl ether, filtered, and dried to obtain a white solid, which was 2-methylisothiourea hydroiodide.

[0051] 2.6 g of 2-methylisothiourea hydroiodide and 3.2 g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS) were added to a reaction flask and stirred at room temperature for 6 h. After the reaction was complete, the byproducts were removed by vacuum distillation to obtain a colorless viscous liquid, which is TMSPAEG.

[0052] Figure 2 The figure shows the 1H NMR spectrum of TMSPAEG. The area ratio of the proton peaks at positions c, d, and e is 1:1:1, and the chemical shifts of each peak correspond one-to-one with the expected positions of the corresponding hydrogen atoms in the target compound structure, which fully demonstrates the successful synthesis of TMSPAEG.

[0053] Example 5 Synthetic guanidinyl functionalized silane coupling agent TMSPAEG 5.25 g of thiourea and 11.75 g of iodomethane were dissolved in a reaction flask containing 35 mL of ethanol and stirred at room temperature in the dark for 10 h. After the reaction was complete, the product was concentrated by rotary evaporation, then precipitated in ice-cold diethyl ether, filtered, and dried to obtain a white solid, which was 2-methylisothiourea hydroiodide.

[0054] 2.6 g of 2-methylisothiourea hydroiodide and 3.2 g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS) were added to a reaction flask and stirred at room temperature for 4 h. After the reaction was complete, the byproducts were removed by vacuum distillation to obtain a colorless viscous liquid, which is TMSPAEG.

[0055] Example 6 Synthetic guanidinyl functionalized silane coupling agent TMSPAEG 5.25 g of thiourea and 11.75 g of iodomethane were dissolved in a reaction flask containing 35 mL of ethanol and stirred at room temperature in the dark for 14 h. After the reaction was complete, the product was concentrated by rotary evaporation, then precipitated in ice-cold diethyl ether, filtered, and dried to obtain a white solid, which was 2-methylisothiourea hydroiodide.

[0056] 2.6 g of 2-methylisothiourea hydroiodide and 3.2 g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS) were added to a reaction flask and stirred at room temperature for 8 h. After the reaction was complete, the byproducts were removed by vacuum distillation to obtain a colorless viscous liquid, which is TMSPAEG.

[0057] Example 7 Synthetic Borneol Functionalized Silane Coupling Agent BS 16g of isoborneol acrylate (BA) and 13g of 3-aminopropyltrimethoxysilane (APTMS) (molar ratio 1:1) were added to a reaction flask, along with an equal volume of anhydrous ethanol. The mixture was stirred at 65°C for 24 hours. After the reaction was complete, the product was purified by rotary evaporation and vacuum drying to obtain a colorless and transparent liquid, BS.

[0058] Figure 3 The figure shows the proton NMR spectrum of BS. The area ratio of the proton peaks at positions c, d, and e is 1:1:1, and the chemical shifts of each peak correspond one-to-one with the expected positions of the corresponding hydrogen atoms in the target compound structure, which fully proves the successful synthesis of BS.

[0059] Example 8 Synthetic Borneol Functionalized Silane Coupling Agent BS 16 g of isoborneol acrylate (BA) and 11.7 g of 3-aminopropyltrimethoxysilane (APTMS) (molar ratio 1:0.9) were added to a reaction flask, along with an equal volume of anhydrous ethanol. The mixture was stirred at 60°C for 20 h. After the reaction was complete, the product was purified by rotary evaporation and vacuum drying to obtain a colorless and transparent liquid, BS.

[0060] Example 9 Synthetic Borneol Functionalized Silane Coupling Agent BS 16 g of isoborneol acrylate (BA) and 14.3 g of 3-aminopropyltrimethoxysilane (APTMS) (molar ratio 1:1.1) were added to a reaction flask, along with an equal volume of anhydrous ethanol. The mixture was stirred at 70°C for 28 h. After the reaction was complete, the product was purified by rotary evaporation and vacuum drying to obtain a colorless and transparent liquid, BS.

[0061] Example 10 Guanidin-borneol dual-function synergistic antibacterial and anti-adhesion coating PU-GM x -BS y Preparation PU-GM x -BS y The composition of TMSPAEG and BS (total moles 0.6 mmol) is shown in Table 1. PU-GM 0.5 -BS 0.5 For example, 116 mg BS (0.3 mmol) and 155 mg TMSPAEG (0.3 mmol) were first dissolved in 1 mL of ethanol, then added to the polyurethane prepolymer, and stirred at 80°C for 2 h to obtain a coating solution. The coating solution was then drop-coated onto a glass substrate treated with piranha solution. After spreading, the substrate was cured at 120°C for 2 h, followed by curing at room temperature for 24 h, ultimately yielding PU-GM. 0.5-BS 0.5 coating.

[0062] Table 1 PU-GM x -BS y Composition of TMSPAEG and BS in the coating

[0063] PU-GM x -BS y The chemical structure of the coating was characterized using Fourier transform infrared spectroscopy (FTIR). Figure 4 As shown in (a), the isocyanate groups in IPDI are at 2260 cm⁻¹ -1 It exhibits strong characteristic stretching vibration peaks at the PU-GM site, while... 0.5 -BS 0.5 The complete disappearance of the absorption peak in the coating indicates that the isocyanate groups have fully reacted during coating formation. BS at 1730 cm⁻¹ -1 A distinct absorption peak appears at 1670 cm⁻¹, attributed to the C=O stretching vibration of its ester group; TMSPAEG shows an absorption peak at 1670 cm⁻¹. -1 The strong absorption peak at this point is attributed to the C=N stretching vibration of the guanidinyl group. Both of these characteristic peaks can be observed in PU-GM. 0.5 -BS 0.5 The observations in the coating indicate that BS and TMSPAEG have been successfully introduced into the coating system. Figure 4 (b) shows PU-GM with different TMSPAEG and BS contents. x -BS y FTIR spectrum of the coating. As TMSPAEG content decreases and BS content increases, the 1670 cm⁻¹... -1 The characteristic peaks attributable to the guanidine group gradually weaken, while the peak at 1730 cm⁻¹... -1 The characteristic peaks attributable to ester groups gradually increase, indicating a good correlation between the relative contents of TMSPAEG and BS in the coating and the formulation's feeding ratio. This further demonstrates that the introduction amount of the two functional components in the coating can be controlled and adjusted through formulation.

[0064] Example 11 Guanidin-borneol dual-function synergistic antibacterial and anti-adhesion coating PU-GM x -BS y Preparation PU-GM x -BS y The composition of TMSPAEG and BS (total moles 0.6 mmol) is shown in Table 1. PU-GM 0.5 -BS 0.5For example, 116 mg BS (0.3 mmol) and 155 mg TMSPAEG (0.3 mmol) were first dissolved in 1 mL of ethanol, then added to the polyurethane prepolymer, and stirred at 70°C for 1 h to obtain a coating solution. The coating solution was then drop-coated onto a glass substrate treated with piranha solution. After spreading, the substrate was cured at 100°C for 1 h and then at room temperature for 20 h to finally obtain PU-GM. 0.5 -BS 0.5 coating.

[0065] Example 12 Guanidin-borneol dual-function synergistic antibacterial and anti-adhesion coating PU-GM x -BS y Preparation PU-GM x -BS y The composition of TMSPAEG and BS (total moles 0.6 mmol) is shown in Table 1. PU-GM 0.5 -BS 0.5 For example, 116 mg BS (0.3 mmol) and 155 mg TMSPAEG (0.3 mmol) were first dissolved in 1 mL of ethanol, then added to the polyurethane prepolymer, and stirred at 90°C for 3 h to obtain a coating solution. The coating solution was then drop-coated onto a glass substrate treated with piranha solution. After spreading, the substrate was cured at 140°C for 3 h, followed by curing at room temperature for 28 h, ultimately yielding PU-GM. 0.5 -BS 0.5 coating.

[0066] Example 13 X-ray photoelectron spectroscopy The PU-GM prepared in Example 10 was analyzed using X-ray photoelectron spectroscopy (KratosAXIS Supra+, UK). 0.5 -BS 0.5 The coating is tested on the surface, and the elemental composition of the coating surface is analyzed.

[0067] XPS results are as follows Figure 5 As shown, in Figure 5 (a) Five elements, C, O, Si, N, I and Sn, were observed in the coating. These elements were distributed on the surface of the coating, with I accounting for as much as 10.36%. Figure 5 High-resolution spectra of C 1s and Si 2p can be observed in (b) and (c). Figure 5The presence of iodine in (d) indicates that the guanidinium group and iodine ion pair were successfully grafted onto the coating. These results suggest that a sol-gel reaction occurred between the siloxanes during the coating curing process, forming a Si-O-Si structure.

[0068] Example 14 Coating transparency test The UV-Vis spectrophotometer used was a Shimadzu UV-3600. Using a blank glass slide as a background, the PU-GM prepared in Example 10 was tested. x -BS y The optical transmittance of the coating was measured three times at different locations on the sample.

[0069] The coating thickness was controlled to approximately 25 μm. The UV-Vis transmission spectrum of the coating is as follows: Figure 6 As shown in (a) above. In the wavelength range of 450–800 nm, all coatings exhibit extremely high optical transmittance, exceeding 99%. Figure 6 (a) shows the PU-GM prepared in Example 10. 0.5 -BS 0.5 Even after the coating is applied to the glass substrate, the school emblem pattern underneath remains clearly visible, fully demonstrating the coating's excellent optical transparency.

[0070] Example 15 Water contact angle test The contact angle meter used is the Betop Scientific DSA-X, and the test liquid is water. Ensure the sample surface is clean, fix the sample on the test stage, and adjust the sample position so that it is centered on the camera. The droplet volume for static contact angle testing is 5.0 μL. Measure the contact angle three times at different locations on the sample and take the average value.

[0071] Ordinary glass treated with piranha solution and PU-GM prepared in Example 10 x -BS y The water contact angle of the coated glass substrate was tested.

[0072] Water contact angle results are as follows Figure 6 As shown in (b), the water contact angle of ordinary glass treated with piranha solution is approximately 32°, exhibiting hydrophilic properties. After coating, due to the presence of siloxane structure and borneol groups, the hydrophobicity of the coated surface is significantly enhanced compared to ordinary glass treated with piranha solution.

[0073] Example 16 Scanning electron microscope The scanning electron microscope used was a Hitachi SU8600. Images were collected from ordinary glass and PU-GM prepared in Example 10. x-BS y The surface morphology of the coated glass substrate was determined, and the chemical composition of the coating surface was analyzed using energy dispersive spectroscopy (EDS). The sample was sputter-coated with gold before testing.

[0074] Scanning electron microscopy (SEM) is used to observe the surface microstructure of coatings. For example... Figure 7 As shown in (a), PU-GM changes with the content of functional components. x -BS y The surface morphology of the coating remained largely unchanged, exhibiting a smooth and dense characteristic, indicating good structural stability. The coating completely covered the substrate surface, with no exposed areas observed, demonstrating excellent film-forming properties and coverage. Furthermore, no obvious shrinkage pores or pinholes were found on the coating surface, indicating a uniform and stable curing process without phase separation or microphase formation, and good compatibility and dispersion of the components within the system. Energy dispersive spectroscopy (EDS) elemental distribution results showed clear and uniform signals for each element on the coating surface. Figure 7 As shown in (b) of the diagram.

[0075] Example 17 Atomic force microscope The atomic force microscope (AFM) was a Bruker Icon model, with a scanning range of 5 μm × 5 μm and a scanning rate of 1.00 Hz. Measurements were taken on the PU-GM prepared in Example 10. x -BS y Surface roughness of the coating.

[0076] Atomic force microscopy (AFM) was used to further analyze the nanoscale morphology of the coating surface. For example... Figure 7 As shown in (c), the coating surface exhibits a highly uniform height distribution and a typical smooth topological morphology. Quantitative roughness analysis results indicate that PU-GM x -BS y The root mean square roughness (Rq) of the coatings is less than 1.5 nm, far below the typical range for smooth coatings (10-20 nm). This low surface roughness indicates that the coatings formed a uniform and dense continuous phase structure during curing. The smooth and dense surface effectively reduces bacterial adhesion sites, thereby improving the coating's anti-adhesion properties. Simultaneously, this uniform surface structure also helps reduce light scattering, improving the coating's optical transparency.

[0077] Example 18 Coating nanoindentation test The nanoindenter used was the NanoTest Vantage, Micro Materials Ltd., Wrexham, UK, equipped with a Berkovich diamond-tipped pen tip. Testing was conducted under depth control, with a maximum preset depth of 1000 nm. During testing, the loading time, dwell time, and unloading time were all 30 seconds. At least three points were marked on each coating.

[0078] PU-GM prepared in Example 10 x -BS y The coating was subjected to nanoindentation testing.

[0079] Studying the mechanical properties of coatings is crucial for evaluating their durability and stability in practical applications. Under the condition of a maximum indentation depth set at 1000 nm, PU-GM... x -BS y The coating undergoes three stages in sequence: loading, holding, and unloading, resulting in a typical load-displacement curve, such as... Figure 8 As shown in (a), it can be observed that, for the same maximum indentation depth, the load required for coatings with different formulations varies significantly, mainly due to the different TMSPAEG contents in the system. PU-GM x -BS y The hardness and elastic modulus of the coating are as follows: Figure 8 As shown in (b), the hardness and elastic modulus of the PU-GM1-B0 coating are 15.28 MPa and 0.6 GPa, respectively. With decreasing TMSPAEG content, both the hardness and elastic modulus of the coating show a significant decreasing trend. This is because the introduction of TMSPAEG promotes the condensation reaction between siloxanes, increases the crosslinking density of the system, and thus enhances the material's resistance to local deformation. However, due to the presence of flexible PTMEG segments in the system, the overall material still exhibits relatively soft mechanical characteristics.

[0080] Example 19 Coating adhesion test The automatic coating adhesion scratch tester is model WS-2005, with a loading rate of 15 N / m and a scratch length of 4 mm.

[0081] PU-GM prepared in Example 10 x -BS y The coating was subjected to nanoindentation testing.

[0082] The interfacial bonding strength between the coating and the substrate is also an important indicator for evaluating coating performance. Adhesion test curves are shown below. Figure 8As shown in (c), the load gradually increases during the test until the coating cracks or fails. The critical load at this point is defined as the adhesion force of the coating. The adhesion results are as follows: Figure 8 As shown in (d), the critical load of the PU-GM1-BS0 coating is 5.62 N. It is noteworthy that the coating adhesion exhibits a trend consistent with the nanoindentation results as the TMSPAEG content changes. This is also attributed to TMSPAEG promoting the formation of the siloxane network structure, thereby improving the overall crosslinking degree and interfacial bonding strength of the system.

[0083] Example 20 Antibacterial effect test Use Gram-positive bacteria ( S. aureus ATCC 25923) and Gram-negative bacteria ( E. coli The antibacterial properties were evaluated using the ATCC25922 standard. The antibacterial properties of the coating against *Escherichia coli* and *Staphylococcus aureus* were investigated using the plate count method. The size was 1 cm. 2 Ordinary glass and PU-GM prepared in Example 10 x -BS y The coated glass substrates (coated samples) were all immersed in 5 mL of a suspension of Escherichia coli and Staphylococcus aureus (approximately 10 mL). 6 CFU·mL 1 The samples were incubated in a shaker at 310 K for 24 hours. After incubation, 100 μL of the solution was spread onto LB agar plates and incubated overnight at 310 K. The antibacterial activity of each sample was quantitatively assessed using the antimicrobial ratio, calculated using equation S1: (S1) Where R1 represents the antibacterial ratio, A represents the average bacterial count on ordinary glass, and B represents the average bacterial count on the coated sample.

[0084] This study selected *Escherichia coli* and *Staphylococcus aureus* as representative Gram-negative and Gram-positive bacterial model microorganisms for systematic evaluation of the PU-GM prepared in Example 10. x -BS y The antibacterial properties of the coating. For example... Figure 9 As shown in (a), ordinary glass is mixed with different proportions of PU-GM x -BS yAfter co-culturing the coated glass substrates with two different bacteria for 24 hours, they were plate-coated and the resulting colony-forming units were recorded. Compared with the control group (ordinary glass), the number of colonies on the surface of each coated glass substrate was significantly reduced, indicating a significant inhibitory effect on bacterial growth. Based on the colony count results, the antibacterial rates of each coating against the two bacteria were further calculated, and the results are summarized in […]. Figure 9 (b) and (c) in the text. Overall, all five coatings exhibited varying degrees of bactericidal activity, indicating that the functional components introduced into the system can effectively exert antibacterial effects. It is worth noting that PU-GM1-BS0 and PU-GM... 0.75 -BS 0.25 Coatings E. coli and S. aureus The sterilization rate exceeded 98%, demonstrating excellent and stable broad-spectrum antibacterial properties. As the TMSPAEG content gradually decreased, the antibacterial effect of the coating showed a certain downward trend, but even under equal-proportion blending conditions, PU-GM... 0.5 -BS 0.5 Coatings E. coli and S. aureus The bactericidal rates still reached 98% and 96% respectively, indicating that the system can maintain high antibacterial activity while taking into account the feasibility of synergistic regulation of components.

[0085] Example 21 Anti-adhesion effect test Use Gram-positive bacteria ( S. aureus ATCC 25923) and Gram-negative bacteria ( E. coli The antibacterial adhesion properties were evaluated using (ATCC 25922). The size was 1 cm. 2 Ordinary glass and PU-GM prepared in Example 10 x -BS y The coated glass substrates (coated samples) were placed in 24-well plates, and 1 mL of Escherichia coli and Staphylococcus aureus suspension (approximately 10 mL) were added to each well. 7 CFU·mL 1 The samples were incubated at 310K for 4 hours. After incubation, all glass slides were gently rinsed with 3 mL of PBS buffer, then immersed in 2 mL of PBS solution and sonicated for 5 min to detach the bacteria adhering to the surface. 100 μL of the solution was spread onto LB agar plates and incubated overnight at 310K. The antibacterial adhesion activity of each sample was quantitatively assessed using the anti-adhesion ratio, calculated using equation S2: (S2) Where R2 represents the anti-adhesion ratio, A represents the average bacterial count on ordinary glass, and B represents the average bacterial count on the coated sample.

[0086] To further evaluate the PU-GM prepared in Example 10 x -BS y To assess the antibacterial adhesion properties of the coating, *Escherichia coli* and *Staphylococcus aureus* were used as model strains in this study. Plate culture results are as follows: Figure 10 As shown in (a) above. Compared with the control group (ordinary glass), PU-GM x -BS y The number of bacterial colonies on the glass substrate surface after coating modification was significantly reduced, and the number of colonies on the coating surface showed a continuous decreasing trend with the gradual increase of BS content in the system, indicating that its antibacterial adhesion ability gradually increased. Based on the colony count results, the anti-adhesion efficiency of each coating against the two bacteria was further calculated, and the results are summarized in […]. Figure 10 (b) and (c) in the diagram. It can be seen that when the molar ratio of BS to TMSPAEG is 1:1, PU-GM... 0.5 -BS 0.5 The coating exhibited excellent anti-adhesion efficiencies of 94.6% and 92.7% against Escherichia coli and Staphylococcus aureus, respectively. With increasing BS content, more borneol structural units with steric hindrance and low surface energy were introduced into the coating surface, effectively weakening the interaction between bacteria and the coating interface and reducing the initial number of bacteria adhering to the surface.

Claims

1. A guanidine-borneol bifunctional synergistic antibacterial and anti-adhesion coating, characterized in that, The guanidin-borneol dual-function synergistic antibacterial and anti-adhesion coating is PU-GM. x -BS y The coating is composed of a polyurethane prepolymer, a guanidine-functionalized silane coupling agent TMSPAEG, and a borneol-functionalized silane coupling agent BS, wherein the polyurethane prepolymer is an isophorone diisocyanate IPDI-terminated polytetrahydrofuran PTMEG prepolymer.

2. The guanidine-borneol bifunctional synergistic antibacterial and anti-adhesion coating according to claim 1, characterized in that, The antibacterial bacteria are Escherichia coli or Staphylococcus aureus.

3. The method for preparing a guanidine-borneol bifunctional synergistic antibacterial and anti-adhesion coating according to claim 1, characterized in that, Includes the following steps: (1) Synthesis of polyurethane prepolymer: PTMEG is dissolved in a solvent, heated, and IPDI and catalyst are added to react and synthesize polyurethane prepolymer; (2) Synthesis of guanidinyl functionalized silane coupling agent TMSPAEG: Thiourea and iodomethane react to generate 2-methylisothiourea hydroiodide, and the product is purified by concentration and precipitation; then 2-methylisothiourea hydroiodide is reacted with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane AEAPTMS to synthesize guanidinyl functionalized silane coupling agent TMSPAEG. (3) Synthesis of borneol-functionalized silane coupling agent BS: Borneol-functionalized silane coupling agent BS is synthesized by reacting isoborneol acrylate BA and 3-aminopropyltrimethoxysilane APTMS. (4) Dissolve BS and TMSPAEG in ethanol, then add them to the polyurethane prepolymer to react and obtain the coating precursor solution; The coating precursor liquid is drop-coated or spin-coated onto the surface of an activated substrate, and after curing, PU-GM is obtained. x -BS y coating.

4. The preparation method according to claim 3, characterized in that, In step (1), the concentration of IPDI is 0.14-0.16 mol / L and the concentration of PTMEG is 0.04-0.06 mol / L.

5. The preparation method according to claim 3, characterized in that, In step (1), the solvent is tetrahydrofuran (THF), the catalyst is dibutyltin dilaurate (DBTDL), and the heating is to 70-90 °C for 1-3 h.

6. The preparation method according to claim 3, characterized in that, In step (2), the reaction conditions for thiourea and iodomethane are to be protected from light and the reaction time is 10-14 h; the reaction time for 2-methylisothiourea hydroiodide with AEAPTMS is 4-8 h.

7. The preparation method according to claim 3, characterized in that, In step (3), the molar ratio of BA to APTMS is 1:0.9-1:1.

1.

8. The preparation method according to claim 3, characterized in that, In step (3), the reaction temperature is 60-70 °C and the reaction time is 20-28 h.

9. The preparation method according to claim 3, characterized in that, In step (4), the concentrations of BS and TMSPAEG dissolved in ethanol are both 0-0.6 mol / L.

10. The preparation method according to claim 3, characterized in that, In step (4), the reaction temperature is 70-90°C and the reaction time is 1-3 h; the substrate surface is activated with piranha solution; the curing conditions are first high temperature curing at 100-140°C for 1-3 h, and then room temperature curing for 20-28 h.

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