Amphiphilic multistage nano SiO2-based masonry cultural relic anti-weathering reinforcing material and preparation method thereof

Abstract

The invention discloses an amphiphilic multistage nano SiO2-based masonry cultural relic anti-weathering reinforcing material and a preparation method thereof, and relates to the technical field of cultural relic protection materials. The method comprises the following steps: preparing multi-stage nano SiO2 particles; in a water-paraffin oil two-phase system, a paraffin template is obtained; the exposed side of the SiO2 particles in the paraffin template reacts with an amino silane coupling agent to modify amino groups, then the other side of the paraffin template is modified with alkyl alkoxy silane or organosilicon quaternary ammonium salt, and amphiphilic Janus SiO2 nanoparticles are prepared; and dispersing the prepared amphiphilic Janus SiO2 nanoparticles into an organic solvent according to the mass fraction of 1 to 5 percent, so as to obtain the amphiphilic multistage nano SiO2-based masonry cultural relic anti-weathering reinforcing material. Based on the Janus SiO2 nanoparticles with three-dimensional multi-stage morphology, the anti-weathering agent is used for anti-weathering protection of masonry cultural relics, endows the masonry cultural relics with excellent hydrophobicity, antibacterial activity and surface reinforcing effect, and has excellent durability so as to keep a long-term anti-weathering reinforcing effect.

Description

An amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics and its preparation method Technical Field

[0001] This invention relates to the field of cultural relic protection materials technology, specifically to an amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics and its preparation method. Background Technology

[0002] Masonry cultural heritage (including ancient buildings, stone carvings, and grottoes) generally faces severe weathering and erosion in open-air environments. Studies show that water and its dissolved substances, as well as the migration and deposition of atmospheric pollutants, are the main weathering factors, leading to surface weathering. Specific damage includes structural cracks, fractures, solution grooves, secondary salt crust formation, and microbial film coverage. Developing weathering-resistant materials with multiple protective effects has become a key requirement for slowing down the deterioration of cultural heritage. Ideal weathering-resistant materials must simultaneously possess three major functions: hydrophobicity, inhibition of microbial growth, and enhanced mechanical strength.

[0003] Biomimetic superhydrophobic interface materials, developed based on the hydrophobic phenomena of natural plant and animal surfaces, have recently attracted attention in the field of cultural heritage conservation (Adv. Colloid Interface Sci., 2025, 335, 103343; J. Colloid Interface Sci., 2021, 591, 239-252). These materials, with their high contact angle and ultra-low adhesion, can both block liquid water erosion and maintain the appearance of cultural relics through self-cleaning mechanisms, exhibiting superior properties compared to traditional organic and inorganic protective materials. However, their application still faces significant limitations at present. As a surface protective coating, it is difficult to effectively penetrate into porous substrates to enhance mechanical strength. Furthermore, the insufficient interfacial bonding strength between the coating and hydrophilic inorganic mineral substrates results in inadequate mechanical support performance, and the weak interfacial bonding force easily leads to coating peeling failure. In addition, the durability of the superhydrophobic surface micro / nano structures is insufficient to support long-term application in open-air environments (Sci. Adv., 2023, 9, eadj1554). The aforementioned core technological bottlenecks severely restrict the practical application value of this type of material in the protection of immovable brick and stone cultural relics.

[0004] Currently, existing technology discloses a durable, high-quality, superhydrophobic, weather-resistant material for masonry and stone, along with its preparation method. The raw materials include partially fluorinated siloxanes and solvents. The partially fluorinated siloxanes are prepared by a one-step reaction of an aminoalkylsilane coupling agent with fluorinated propylene oxide at different molar ratios. This material can be used for weathering protection on the surfaces of various common masonry and stone artifacts, exhibiting excellent superhydrophobicity, stain resistance, and durability. However, the material prepared by this method has limited properties and lacks antibacterial and reinforcing properties.

[0005] Existing technology discloses an inorganic-organic superhydrophobic nanocomposite material for weathering protection of stone cultural relics. The raw materials include a hydrophobic organosilicon liquid phase and nano-ZnO / SiO2 (weight fraction 0.2-4%, average particle size 20-200 nm). This material can form a micron-nano bilayer structure with low surface energy on the surface of sandstone cultural relics, exhibiting superhydrophobicity and self-cleaning functions. However, this method involves multiple steps in preparing the ZnO-coated SiO2 core-shell nanoparticles (ZnO / SiO2), and the material does not exhibit strengthening properties or excellent durability.

[0006] Existing technology discloses a superhydrophobic, self-cleaning fluorosilicone coating material, the raw materials of which include a fluorosilicone dual-hydrophobic treatment agent and a solvent. The fluorosilicone dual-hydrophobic treatment agent is prepared in one step by reacting an aminoalkylsilane coupling agent and a hexafluorooxypropane trimer in a 1:1 molar ratio. Using this material, hydrophobic and oleophobic self-cleaning coatings can be prepared on the surfaces of building bricks and stone with different porosities, while maintaining the surface color and original breathability of the substrate. However, the preparation process of this material is relatively complex, and the treatment of toxic byproducts generated during the preparation process is highly demanding. Furthermore, this material does not exhibit antibacterial or reinforcing properties.

[0007] Existing technology discloses a method for preparing a transparent cooling and self-cleaning coating for stone cultural relics. The preparation method includes seven steps: preparation of a composite nano-dispersion of SiO2, TiO2, and ZnO; preparation of a nano-SiO2 dispersion and a silane coupling agent dispersion; and compounding the composite nano-dispersion with the nano-SiO2 dispersion. This method involves complex material and coating preparation processes, and the prepared coating does not possess antibacterial or reinforcing properties.

[0008] Existing technology discloses a method for reinforcing and protecting exposed brick and stone cultural relics based on nano-SiO2 composite materials. The main raw materials include nano-SiO2 and tetraethyl orthosilicate, and the application process involves cellulose lamination. The nano-SiO2 aqueous dispersion exhibits excellent permeability, with an effective penetration and reinforcement depth of 2 cm or more, ensuring a deep reinforcement effect. This method also imparts a certain degree of hydrophobicity (water contact angle > 100°) to the brick and stone cultural relic substrate after reinforcement. However, this method does not construct a superhydrophobic, self-cleaning, and weather-resistant layer on the surface of the brick and stone cultural relic, nor does it possess antibacterial properties.

[0009] The technical solutions provided by the aforementioned documents and patents have solved some problems in the protection of brick and stone cultural relics from weathering, but factors such as the single function of the materials, poor bonding with the substrate, and poor durability limit their large-scale production and application. Summary of the Invention

[0010] To address the shortcomings of the aforementioned background technologies, this invention primarily solves the problems of existing weathering-resistant materials, such as limited functionality, poor adhesion to the substrate, and poor durability, which restrict their large-scale application and promotion. This invention provides an amphiphilic, multi-level nano-SiO2-based weathering-resistant reinforcement material for brick and stone cultural relics and its preparation method. This material, based on Janus SiO2 nanoparticles with a three-dimensional multi-level morphology, is used for weathering protection of brick and stone cultural relics, imparting excellent hydrophobicity, antibacterial properties, and surface reinforcement to these relics, while also exhibiting excellent durability to maintain long-term weathering-resistant reinforcement effects. The method provided by this invention can solve the problems of existing weathering-resistant materials for brick and stone cultural relics, such as complex preparation processes, limited functionality, poor adhesion to the substrate, and poor durability, which make them unsuitable for large-scale production and application.

[0011] The first objective of this invention is to provide a method for preparing an amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics, comprising the following steps: preparing an aqueous dispersion of a surfactant and adding an alkaline catalyst to obtain an aqueous phase; dispersing a silicon source in an organic solvent to form an oil phase, then adding it to the aqueous phase, and stirring the reaction at 50-60°C to obtain multi-level nano-SiO2 particles; activating the surface hydroxyl groups of the multi-level nano-SiO2 particles under the action of a strong oxidant, and then preparing a Pickering emulsion in a water-paraffin oil two-phase system using the multi-level nano-SiO2 particles as a solid emulsifier; allowing the emulsion to stand and cool to solidify the paraffin oil so that the SiO2 particles are partially embedded in solid paraffin to obtain a paraffin template; then reacting one side of the SiO2 particles exposed in the paraffin template with an aminosilane coupling agent to modify the amino group, dissolving and removing the paraffin with chloroform, and then modifying the other side with an alkylalkoxysilane or an organosilicon quaternary ammonium salt, finally obtaining an amphiphilic Janus material with one side modified with a polar amino group and the other side modified with a non-polar long-chain alkyl group. SiO2 nanoparticles; the prepared amphiphilic Janus SiO2 nanoparticles are dispersed in an organic solvent at a mass fraction of 1-5% to obtain an amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics.

[0012] Preferably, the aminosilane coupling agent is one or more of the following compounds with the following structural formulas:

[0013] In the formula, R1 is methyl and R2 is ethyl.

[0014] Preferably, the alkylalkoxysilane has the following structural formula:

[0015] In the formula, R1, R2, and R3 are methyl or ethyl; the organosilicon quaternary ammonium salt has the following structural formula:

[0016] In the formula, R is a methyl, ethyl, or hydrogen atom.

[0017] Preferably, the organic solvent is cyclohexane or anhydrous ethanol; the alkaline catalyst is NaOH; and the surface activation of the multi-level nano-SiO2 particles using a strong oxidant includes: pretreating the surface of the multi-level nano-SiO2 particles in a water bath at 80-85°C using a strong oxidant to activate the hydroxyl groups on the particle surface; wherein, the strong oxidant is HNO3.

[0018] Preferably, the multi-level nano-SiO2 particles are virus-like nanoparticles with a particle size of 30-100 nm; the virus-like nanoparticles have a three-dimensional multi-level morphology, with a core diameter of about 30-70 nm and a surface needle or tubular protrusion length of about 5-20 nm.

[0019] Preferably, when modifying one side of the multi-level nano-SiO2 particles with an amino group and the other side with an alkylalkoxysilane or organosilicon quaternary ammonium salt, the reaction is carried out by thoroughly stirring in a water-alcohol composite system and at 40-50°C.

[0020] The second objective of this invention is to provide an amphiphilic, multi-level nano-SiO2-based material for weathering prevention and reinforcement of brick and stone cultural relics.

[0021] The third objective of this invention is to provide an application of an amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics in the protection and restoration of brick and stone cultural relics.

[0022] The fourth objective of this invention is to provide a weathering-resistant reinforcement layer, which uses an amphiphilic multi-level nano-SiO2-based weathering-resistant reinforcement material for brick and stone cultural relics. The material is uniformly applied to the surface of the brick and stone cultural relics by spraying or brushing. After the solvent has completely evaporated, the weathering-resistant reinforcement layer is formed on the surface of the brick and stone cultural relics. The capillary hydrophobicity of the weathering-resistant layer formed on a brick and stone substrate with different mineral compositions and porosity of 2%-45% is higher than 90%.

[0023] Preferably, the water contact angle of the weathering-resistant reinforcement layer is 155°-167°, and the roll-off angle is 2.8°-6.5°; the mechanical strength of the weathering-resistant reinforcement layer is increased by 23%; when the concentration of the nanocomposite material in the weathering-resistant reinforcement layer is 0.2-1.5 g / L, its antibacterial efficiency against Gram-positive / negative bacteria is over 86%.

[0024] Compared with the prior art, the beneficial effects of the present invention are: (1) The preparation process of the weathering-resistant reinforcement material of the present invention is simple, the raw materials are green, environmentally friendly, and of moderate cost, and no high / perfluorinated compounds that are harmful to humans and the environment are used. In practical applications, the material dispersion can be coated onto the surface of the substrate by spraying or brushing to obtain a weathering-resistant reinforcement layer with superhydrophobic, antibacterial and reinforcement properties. The whole process does not require heating, pressurization or special equipment, consumes little energy, and has good prospects for promotion and application.

[0025] (2) The weathering-resistant reinforcement material of the present invention forms a weathering-resistant layer on the surface of brick and stone cultural relics with a water contact angle of 155°-167° and a roll-off angle of 2.8°-6.5°, which meets the technical requirements of superhydrophobic and self-cleaning coating.

[0026] (3) The weathering reinforcement material of the present invention has high performance, and the actual amount of material used is not higher than 20 g / m³. 2 It is possible to construct a multifunctional weathering-resistant and reinforcing layer on the surface of brick and stone cultural relics with different porosities and mineral compositions.

[0027] (4) The weathering-resistant reinforcement layer obtained by the method of the present invention has excellent capillary hydrophobic properties. The capillary hydrophobic efficiency of different masonry substrates with porosity of 2%-45% is higher than 90% after treatment with this material.

[0028] (5) The weathering-resistant reinforcement material of the present invention exhibits high antibacterial properties, with an antibacterial efficiency of 86% or higher against Gram-positive / negative bacteria at a concentration of 0.2-1.5 g / L. The antibacterial activity originates from the organosilicon quaternary ammonium salt modified on the non-polar side of the surface of amphiphilic Janus SiO2 particles. The quaternary ammonium group (N...) + It can bind to the surface of bacteria through electrostatic interaction, thereby destroying the cell membrane and killing bacteria. Moreover, its antibacterial properties have a broad-spectrum and long-lasting effect, and it is safe, non-toxic, and meets environmental protection standards.

[0029] (6) The surface elastic modulus and hardness of the stone substrate treated with the amphiphilic Janus SiO2 nanoparticles of this invention are increased by an average of 23% or more. The weathering-resistant layer reinforcement performance comes from the alkoxy groups [R'-Si(OR)3] modified on the non-polar side of the amphiphilic Janus SiO2 particle surface, the special morphology of the multi-level morphology nano-SiO2 particles, and the interaction between the amino groups modified on the polar side and the substrate. First, an alkoxysilane or organosilicon quaternary ammonium salt molecule contains three reactive alkoxy groups, which generate Si-O-Si bond-rich polysiloxane (silicone network) through in-situ polycondensation reaction (sol-gelation) to bond the constituent minerals of the porous brick and stone substrate, thereby improving the mechanical strength of the substrate (reinforcement effect). Secondly, the virus-like nano-SiO2 particles have needle / tubular protrusions on their surface, exhibiting a distinct three-dimensional multi-level morphology and extremely high specific surface area, resulting in strong mechanical interlocking with the rough, porous masonry substrate. Thirdly, the microscopic three-dimensional morphology of the multi-level nano-SiO2 can be used as a three-dimensional inorganic filler to fill the silica gel network, providing reinforcement and toughening effects, further enhancing the weathering-resistant layer's strength. Fourthly, the amino groups modified on the polar side of the amphiphilic Janus SiO2 particles interact strongly with the hydrophilic / polar masonry matrix (mainly composed of hydrophilic minerals such as quartz and feldspar) through hydrogen bonding and van der Waals non-covalent interactions, further improving the weathering-resistant layer's reinforcement effect.

[0030] (7) The weathering-resistant layer formed by the method of the present invention maintains the appearance characteristics and breathability of brick and stone cultural relics. The color change of the substrate surface after weathering treatment is less than that that can be distinguished by the human eye (ΔE). * <5), and the loss of water vapor diffusion rate inside the base is <8%, which meets the requirements for cultural relic protection.

[0031] (8) The weathering-resistant reinforcement material of the present invention forms a weathering-resistant layer with strong adhesion to the masonry matrix and strong resistance to mechanical peeling and mechanical wear. After 100 cycles of tape peeling test, the surface still maintains superhydrophobic and self-cleaning properties; at the same time, it has excellent resistance to mechanical wear such as sandpaper abrasion and can withstand 100 cycles of 1000-grit sandpaper abrasion. The excellent durability of the weathering-resistant layer comes from three aspects. First, due to the hierarchical morphology of Janus SiO2 nanoparticles, the contact area between them and the porous, rough masonry matrix is ​​large, and the mechanical interlocking / bonding effect is strong. Second, since the main components of the masonry matrix, such as quartz, feldspar, and calcite, are typical hydrophilic minerals, the polar side (amino modification) of the amphiphilic Janus SiO2 particles has significant non-covalent interactions (hydrogen bonding and van der Waals forces) with the hydrophilic / polar characteristics of quartz and feldspar, resulting in a tight bond between the material and the substrate. Third, the unique virus-like morphology of the amphiphilic Janus SiO2 particles allows them to maintain their needle / tubular protrusions even after mechanical wear and chemical corrosion, ensuring the necessary micro-nano hierarchical rough structure and maintaining superhydrophobic properties, thus exhibiting excellent durability. Attached Figure Description

[0032] Figure 1 is a transmission electron microscope image of the virus-like nano-SiO2 particles prepared in Example 1.

[0033] Figure 2 shows the changes in surface elastic modulus and hardness of the stone substrate before and after weathering protection treatment in Example 1.

[0034] Figure 3 shows the antibacterial properties of the amphiphilic Janus SiO2 particles prepared in Example 3.

[0035] Figure 4 shows a scanning electron microscope image of the weathering-resistant reinforcement layer prepared in Example 4 and a schematic diagram of the surface water contact angle.

[0036] Figure 5 is a scanning electron microscope image of the surface of the stone substrate after treatment with nano-SiO2 particles in Example 6. Detailed Implementation

[0037] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0038] The purpose of this invention is to provide an amphiphilic, multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics, and its preparation method. This addresses the problems of existing anti-weathering materials for brick and stone cultural relics, such as complex preparation processes, limited functionality, poor adhesion to the substrate, and poor durability, making them unsuitable for large-scale production and application.

[0039] To achieve the above objectives, the first aspect of this invention provides a method for preparing an amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics, comprising the following steps: preparing an aqueous dispersion of a surfactant and adding an alkaline catalyst to obtain an aqueous phase; dispersing a silicon source in an organic solvent to form an oil phase, then adding it to the aqueous phase, and stirring the reaction at 50-60°C to obtain multi-level nano-SiO2 particles; activating the surface hydroxyl groups of the multi-level nano-SiO2 particles under the action of a strong oxidant, and then preparing a Pickering emulsion in a water-paraffin oil two-phase system using the multi-level nano-SiO2 particles as a solid emulsifier; allowing the emulsion to stand and cool to solidify the paraffin oil so that the SiO2 particles are partially embedded in solid paraffin to obtain a paraffin template; then reacting one side of the SiO2 particles exposed in the paraffin template with an aminosilane coupling agent to modify the amino group, dissolving and removing the paraffin with chloroform, and then modifying the other side with an alkylalkoxysilane or an organosilicon quaternary ammonium salt, finally obtaining an amphiphilic Janus material with one side modified with a polar amino group and the other side modified with a non-polar long-chain alkyl group. SiO2 nanoparticles; the prepared amphiphilic Janus SiO2 nanoparticles are dispersed in an organic solvent at a mass fraction of 1-5% to obtain an amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics.

[0040] In the preparation of amphiphilic Janus SiO2 nanoparticles, this invention first utilizes single micelles for directional self-assembly in an oil-water biphase system to prepare nano-SiO2 particles with hierarchical morphologies. An aqueous dispersion of a surfactant is prepared, heated (50-60°C) and thoroughly stirred under the action of an appropriate catalyst to prepare the aqueous phase. A silicon source is dispersed in an organic solvent to prepare the oil phase, which is then added to the prepared aqueous phase. After heating (50-60°C) and thoroughly stirring, the nano-SiO2 particles with hierarchical morphologies are obtained. As shown in the figure, the hierarchical morphological nano-SiO2 particles are virus-like nanoparticles with a particle size of 30-100 nm. These virus-like nano-SiO2 particles possess a three-dimensional hierarchical morphology, with a core diameter of approximately 30-70 nm and surface needle / tubular protrusions with a length of approximately 5-20 nm.

[0041] Secondly, using multi-level morphological nano-SiO2 particles as particle emulsifiers, paraffin templates for the preparation of amphiphilic Janus particles were prepared in a water-paraffin oil two-phase system. First, the hydroxyl groups on the surface of the nano-SiO2 particles were activated using a strong oxidizing agent (method referenced in J. Appl. Polym. Sci., 2015, 132:42047, etc.). Then, using melted paraffin oil as the oil phase, a Pickering emulsion was prepared in an aqueous dispersion of surfactant, utilizing surface-activated multi-level nano-SiO2 particles as particle emulsifiers (SiO2 particles were located at the oil-water interface and stabilized the emulsion). After emulsification, the emulsion was allowed to stand and rapidly cooled to solidify the paraffin oil. After filtration and drying, the paraffin templates, with SiO2 particles partially embedded in paraffin spheres and partially exposed, were collected.

[0042] Finally, asymmetric chemical modification was performed on the surface of the paraffin template to prepare amphiphilic Janus SiO2 nanoparticles. An alcoholic solution of an aminosilane coupling agent was prepared and added to the paraffin template, modifying the exposed side of the template with amino groups. The amino-modified paraffin template was then dispersed in chloroform to dissolve and remove the exposed hydroxyl groups. It was then reacted with an alkylalkoxysilane or an organosilicon quaternary ammonium salt in a water-alcohol composite system under thorough stirring and heating (40-50℃). After centrifugation, washing, and drying, amphiphilic Janus SiO2 nanoparticles were obtained with one side modified by a polar amino group and the other side modified by a non-polar long-chain alkyl group. At this point, due to the hierarchical rough structure of the hierarchical SiO2 nanoparticles at the micro-nano scale, the modification of one side with a low surface energy long-chain alkyl group results in superhydrophobic properties, while the other side exhibits hydrophilicity due to the presence of the polar amino group.

[0043] The aminosilane coupling agent is one or more of the following compounds with the following structural formulas:

[0044] In the formula, R1 is methyl and R2 is ethyl.

[0045] The alkylalkoxysilane has the following structural formula:

[0046] In the formula, R1, R2, and R3 are methyl or ethyl; the organosilicon quaternary ammonium salt has the following structural formula:

[0047] In the formula, R is a methyl, ethyl, or hydrogen atom.

[0048] The organic solvent is cyclohexane or anhydrous ethanol; the alkaline catalyst is NaOH; the surface activation of multi-level nano-SiO2 particles is performed using a strong oxidant, including: pre-treating the surface of the multi-level nano-SiO2 particles in a water bath at 80-85℃ using a strong oxidant to activate the hydroxyl groups on the particle surface; wherein, the strong oxidant is HNO3.

[0049] When modifying one side of multi-level nano-SiO2 particles with amino groups and the other side with alkylalkoxysilanes or organosilicon quaternary ammonium salts, the reaction is carried out in a water-alcohol composite system with thorough stirring and at 40-50℃.

[0050] The second aspect of this invention provides an amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics.

[0051] The third aspect of this invention provides an application of an amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics in the protection and restoration of brick and stone cultural relics.

[0052] The fourth aspect of this invention provides a weathering-resistant reinforcement layer, which uses an amphiphilic multi-level nano-SiO2-based weathering-resistant reinforcement material for brick and stone cultural relics. The material is uniformly applied to the surface of the brick and stone cultural relics by spraying or brushing. After the solvent has completely evaporated, the weathering-resistant reinforcement layer is formed on the surface of the brick and stone cultural relics. The capillary hydrophobicity of the weathering-resistant layer formed on the brick and stone substrate with different mineral compositions and porosity of 2%-45% is higher than 90%.

[0053] For example, the prepared amphiphilic Janus SiO2 nanoparticles are dispersed in an organic solvent at a mass fraction of 1-5% to prepare a weathering-resistant reinforcement material dispersion. The dispersion is then uniformly applied to the surface of the brick and stone artifact by spraying or brushing. After the solvent has completely evaporated, a weathering-resistant reinforcement layer is formed on the surface of the brick and stone artifact.

[0054] The water contact angle of the weathering-resistant reinforcement layer is 155°-167°, and the roll-off angle is 2.8°-6.5°, indicating that the weathering-resistant reinforcement layer has excellent hydrophobic properties.

[0055] The weathering-resistant reinforcement layer exhibits significant reinforcement performance, with the average mechanical strength of the stone substrate surface increasing by 23% after weathering treatment. When the concentration of nanocomposite materials in the weathering-resistant reinforcement layer is 0.2-1.5 g / L, its antibacterial efficiency against Gram-positive / negative bacteria reaches over 86%.

[0056] The weathering-resistant reinforcement layer exhibits excellent adhesion to the substrate, maintaining its superhydrophobic and self-cleaning properties even after 120 or more cycles of tape peeling tests. Simultaneously, it demonstrates outstanding resistance to mechanical abrasion such as sandpaper abrasion, retaining its superhydrophobic and self-cleaning properties even after 100 cycles of abrasion with 1000-grit sandpaper.

[0057] It should be noted that, unless otherwise specified, the experimental methods used in this invention are all conventional methods; and the reagents and materials used, unless otherwise specified, are all commercially available.

[0058] Example 1, Step 1: Preparation of multi-level nano-SiO2 particles. At room temperature, 1.6 g of cetyltrimethylammonium bromide (CTAB) was ultrasonically dispersed in 80 mL of deionized water in a reaction flask; 0.6 mL of NaOH (0.1 M) was added to the flask and stirred at 60 °C; then a mixture of 20 mL of tetraethyl orthosilicate (7 mL) and cyclohexane (13 mL) was added, and the mixture was reacted at 60 °C for 48 hours; after centrifugation and washing, a white precipitate was obtained, and CTAB was removed by reflux with acetone for 12 hours. Finally, multi-level nano-SiO2 particles were obtained by washing and drying.

[0059] Step 2, Preparation of the paraffin template: In a flask equipped with a reflux condenser, 500 mg of the multi-level nano-SiO2 particles prepared in Step 1 were weighed and dispersed in 30 mL of HNO3 (2M). After stirring thoroughly in a water bath (85°C) for 8 hours, the mixture was cooled, centrifuged, and dried to obtain a solid powder. 2.0 mg of didodecyl dimethyl ammonium bromide (DDAB) was weighed and dissolved in 20 mL of water. 60 mg of activated SiO2 particles were added and ultrasonically dispersed. Then, 1.4 g of paraffin was added, and the mixture was heated in a water bath at 75°C until the paraffin melted. Emulsification was performed using a homogenizer at 10,000 rpm for 3 minutes, for a total of 4 times (with 1-minute intervals). Subsequently, the mixture was rapidly cooled in an ice-water mixture. After filtration, rinsing, and drying, a paraffin template with silica partially embedded in solid paraffin was obtained.

[0060] Step 3: Preparation of amphiphilic Janus SiO2 nanoparticles. 2 mL of 3-aminopropyltriethoxysilane (APTES) was measured and dispersed in 10 mL of deionized water in a reaction flask, and hydrolyzed at 30 °C for 30 minutes. Then, 500 mg of the paraffin template prepared in Step 2 was added to an ethanol (20 mL) dispersion, and the mixture was reacted at 35 °C for 6 hours. After the reaction, the mixture was centrifuged, washed, and the paraffin was removed by dissolving in chloroform. Next, 2.5 mL of dodecyltrimethoxysilane was measured and dispersed in 10 mL of anhydrous ethanol, and the above-reacted nano-SiO2 particles were added. The mixture was reacted at 50 °C for 12 hours. After washing, centrifugation, and drying, amphiphilic Janus SiO2 nanoparticles were obtained.

[0061] Step 4: Prepare the weathering-resistant material. Take 18 mg of the product from Step 3 and disperse it in 2.3 mL of anhydrous ethanol under magnetic stirring to prepare a 1% concentration weathering-resistant reinforcement material. The percentage is by mass. Step 5: Prepare a multifunctional weathering-resistant reinforcement layer using the weathering-resistant material. Brush the weathering-resistant material prepared in Step 4 onto the surface of a 3×3 cm² yellow sandstone sample (quartz sandstone, porosity <15%) (effective material dosage is 20 g / m²). 2 After the solvent has completely evaporated, the weathering-resistant reinforcement layer is obtained.

[0062] The multi-level nano-SiO2 particles prepared in step 1 are shown in Figure 1, with an average particle size of 70 nm and an average needle / tube length of 18 nm. Contact angle testing showed that the final weathering-resistant reinforcement layer possesses superhydrophobic and self-cleaning properties, with a surface water contact angle of 158°±2.3° and a roll-off angle of 3.8°. The capillary hydrophobicity, air permeability, and surface color of the weathering-resistant layer were tested using EU standards. The results showed that the weathering-resistant layer effectively inhibits capillary water penetration (hydrophobic efficiency not less than 90% within 24 hours) and does not alter the original air permeability (water vapor diffusion rate loss of 8%) or surface color (ΔE) of the substrate. * =4.2, below the upper limit of color change 5). The micro-nano mechanical properties of the weathering-resistant reinforcement layer were tested, as shown in Figure 2. After weathering treatment, the elastic modulus and hardness of the substrate surface increased from 18.6 GPa and 2.3 GPa to 23 GPa and 2.9 GPa, respectively (an average increase of 24%). The adhesion between the weathering-resistant reinforcement layer and the substrate was tested using a tape peel test. The results showed that the peel mass of the weathering layer surface was less than 0.5 mg / 10⁻¹⁰ within 100 peel test cycles. -3 / mm 2 It exhibits high bonding strength with the substrate, meeting the application requirements for weathering prevention on the surface of exposed brick and stone cultural relics. Furthermore, the excellent durability of the weathering-resistant reinforcement was further verified through 1000-grit sandpaper polishing experiments and acid / alkali droplet corrosion tests.

[0063] Example 2, Step 1: Preparation of multi-level nano-SiO2 particles. In this example, Step 1 is the same as in Example 1.

[0064] Step 2, preparation of the paraffin template: In this embodiment, step 2 is the same as in embodiment 1.

[0065] Step 3: Preparation of amphiphilic Janus SiO2 nanoparticles. 2 mL of 3-aminopropyltriethoxysilane (APTES) was dispersed in 10 mL of deionized water in a reaction flask and hydrolyzed at 30 °C for 30 minutes. Then, 500 mg of the paraffin template prepared in Step 2 was added to an ethanol (20 mL) dispersion, and the mixture was reacted at 35 °C for 6 hours. After the reaction, the mixture was centrifuged, washed, and the paraffin was removed by dissolving in chloroform. Next, 2.5 mL of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride was dispersed in 10 mL of anhydrous ethanol, and the above-reacted nano-SiO2 particles were added. The mixture was reacted at 50 °C for 12 hours. After washing, centrifugation, and drying, amphiphilic Janus SiO2 nanoparticles were obtained.

[0066] Step 4: Prepare the weathering-resistant material. Take 18 mg of the product from Step 3 and disperse it in 2.3 mL of anhydrous ethanol under magnetic stirring to prepare a 1% weathering-resistant reinforcement material. The percentage is by mass. Step 5: Prepare a multifunctional weathering-resistant reinforcement layer using the weathering-resistant material. Brush the weathering-resistant material prepared in Step 4 onto the surface of a yellow sandstone sample with a surface area of ​​3 × 3 square centimeters (effective material dosage is 20 g / m²). 2 After the solvent has completely evaporated, the weathering-resistant reinforcement layer is obtained.

[0067] In this embodiment, steps 1, 2, and 5 are the same as in Example 1, thus the resulting multi-level nano-SiO2 particles and paraffin template are highly similar. In step 3, an organosilicon quaternary ammonium salt is used instead of an alkylalkoxysiloxane, which has a longer alkyl chain (octadecyl) and also contains a quaternary ammonium group (N). + The hydrophobicity of the weathering-resistant reinforcement layer was tested, with a water contact angle of 166.2°±2.8° and a roll-off angle of 2.6°, both performance indicators superior to those of Example 1. The main reason is the modification of the non-polar / hydrophobic side of the particles with substances having longer alkyl chains, which further enhances the hydrophobicity. OD was used. 600 The antibacterial properties of the material were tested, and the results showed that the antibacterial properties were outstanding due to the modification of the particle surface with quaternary ammonium groups, which have antibacterial properties. As shown in Figure 3, when the material concentration was 0.8-1.0 g / L, the antibacterial efficiency against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria was 95% or higher. In addition, the prepared weathering-resistant reinforcement layer exhibited excellent durability, and its superhydrophobic and self-cleaning properties could withstand at least 120 cycles of sandpaper abrasion.

[0068] Example 3, Step 1: Preparation of multi-level nano-SiO2 particles. At room temperature, 2.1 g of hexadecyltrimethylammonium bromide (CTAB) was ultrasonically dispersed in 80 mL of deionized water in a reaction flask; 0.6 mL of NaOH (0.1 M) was added to the flask and stirred at 60 °C; then a mixture of 20 mL of tetraethyl orthosilicate (7 mL) and cyclohexane (13 mL) was added, and the mixture was reacted at 60 °C for 72 hours; after centrifugation and washing, a white precipitate was obtained, and CTAB was removed by reflux with acetone for 12 hours; finally, multi-level morphology nano-SiO2 particles were obtained by washing and drying.

[0069] Step 2, preparation of the paraffin template: In this embodiment, step 2 is the same as in embodiment 1.

[0070] Step 3, Preparation of amphiphilic / superhydrophobic Janus SiO2 nanoparticles: 2 mL of 3-aminopropyltrimethoxysilane (APTMS) was measured and dispersed in 10 mL of deionized water in a reaction flask, and hydrolyzed at 30 °C for 30 min. Subsequently, 500 mg of the paraffin template prepared in Step 2 was added to an ethanol (20 mL) dispersion, and the reaction was carried out at 35 °C for 6 h. After the reaction, the nanoparticles were centrifuged and washed, and the paraffin was removed by dissolving in chloroform. Then, 2.5 mL of dodecyltriethoxysilane was measured and dispersed in 10 mL of anhydrous ethanol, and the nanoparticles prepared above were added. The reaction was carried out at 50 °C for 10 h. After washing, centrifugation and drying, amphiphilic Janus SiO2 nanoparticles were obtained.

[0071] Step 4: Prepare a multifunctional weathering-resistant reinforcement layer using the weathering-resistant material. Take 14 mg of the product from Step 3 and disperse it in 1.8 mL of anhydrous ethanol under magnetic stirring to prepare a 1% concentration weathering-resistant reinforcement material. The percentage is a mass ratio. Step 5: Prepare a multifunctional weathering-resistant reinforcement layer using the weathering-resistant material. Brush the weathering-resistant material prepared in Step 4 onto the surface of a yellow sandstone sample with a surface area of ​​3 × 3 square centimeters (effective material dosage is 15 g / m²). 2 After the solvent has completely evaporated, the weathering-resistant reinforcement layer is obtained.

[0072] In this embodiment, a higher surfactant concentration (0.075 mol / L) was used in the preparation of multi-level nano-SiO2 particles than in Example 1, while keeping other parameters unchanged. Therefore, the morphology of the prepared nano-SiO2 particles differed. The average particle size of the nano-SiO2 particles was smaller, at 60 nm, and the surface needle / tube protrusions were also shorter, averaging 11 nm. Although a different alkylalkoxysilane (dodecyltriethoxysilane) was used in step 3 compared to Example 1, the actual alkyl chain length of each molecule was the same (twelve alkyl groups). The hydrophobicity of the weathering-resistant reinforcement layer was tested, showing outstanding superhydrophobicity and self-cleaning properties. The surface water contact angle was 157.9°±2.8°, and the roll-off angle was 3.6°, with relevant performance indicators close to those in Example 1. Capillary hydrophobicity testing showed that the weathering-resistant reinforcement layer exhibited excellent long-term hydrophobicity, with a hydrophobic efficiency exceeding 90% after 24 hours. Simultaneously, the weathering-resistant layer also effectively maintained the surface color of the substrate (ΔE). * <5) and breathability (water vapor diffusion rate loss of 9%). In addition, the durability of the weathering-resistant reinforcement layer was verified by abrasion time with 1000-grit sandpaper, and the results showed that the surface water contact was still above 152.5° after 120 sanding cycles.

[0073] Example 4, Step 1: Preparation of multi-level nano-SiO2 particles. In this example, Step 1 is the same as in Example 3.

[0074] Step 2, preparation of the paraffin template: In this embodiment, step 2 is the same as in embodiment 3.

[0075] Step 3, Preparation of amphiphilic / superhydrophobic Janus SiO2 nanoparticles: 2 mL of 3-aminopropyltrimethoxysilane (APTMS) was measured and dispersed in 10 mL of deionized water in a reaction flask, and hydrolyzed at 30 °C for 30 min. Then, 500 mg of the paraffin template prepared in Step 2 was added to an ethanol (20 mL) dispersion, and the reaction was carried out at 35 °C for 6 h. After the reaction, the nanoparticles were centrifuged and washed, and the paraffin was removed by dissolving in chloroform. Then, 5 mL of dodecyltriethoxysilane was measured and dispersed in 10 mL of anhydrous ethanol, and the nanoparticles prepared above were added. The reaction was carried out at 50 °C for 12 h. After washing, centrifugation and drying, amphiphilic Janus SiO2 nanoparticles were obtained.

[0076] Step 4: Prepare a multifunctional weathering-resistant reinforcement layer using the weathering-resistant material. Take 14 mg of the product from Step 3 and disperse it in 1.8 mL of anhydrous ethanol under magnetic stirring to prepare a 1% concentration weathering-resistant reinforcement material. The percentage is a mass ratio. Step 5: Prepare a multifunctional weathering-resistant reinforcement layer using the weathering-resistant material. Brush the weathering-resistant material prepared in Step 4 onto the surface of a yellow sandstone sample with a surface area of ​​3 × 3 square centimeters (effective material dosage is 15 g / m²). 2After the solvent has completely evaporated, the weathering-resistant reinforcement layer is obtained.

[0077] In this embodiment, steps 1 and 2 are the same as in Example 3, except that in step 3, the amount of alkylalkoxysilane used is increased (from 2.5 ml to 5 ml) and the volume fraction is increased (from 20% to 33.3%). Therefore, the multi-level nano-SiO2 particles and paraffin template prepared in steps 1 and 2 are highly similar to those in Example 3. The final weathering-resistant reinforced layer has a surface water contact angle of 165.2°±2.1° and a roll-off angle of 2.6°, all of which are superior to the hydrophobicity in Example 3. Figure 4 shows a scanning electron microscope image of the weathering-resistant reinforced layer (the micro-nano scale rough structure is clearly visible) and a schematic diagram of its surface water contact angle. Capillary hydrophobicity testing shows that the weathering-resistant reinforced layer has a hydrophobic efficiency of over 92% after 24 hours, which is also superior to that of Example 3. The mechanical properties of the weathering-resistant reinforced layer were tested using a nanoindenter, and the results showed that the surface elastic modulus and hardness of the substrate increased by an average of about 23% after weathering treatment. Furthermore, the corrosion resistance of the weathering-resistant reinforcement layer was tested using acetic acid solution (pH=3) and potassium hydroxide solution (pH=14), confirming its excellent corrosion resistance. This example illustrates that, under the same conditions of multi-level nano-SiO2 particle morphology and size, paraffin template, and asymmetric functionalization, the density of non-polar / hydrophobic grafted functionalized groups on the surface of amphiphilic Janus SiO2 nanoparticles significantly affects the final hydrophobicity and reinforcement performance of the product. Specifically, a higher volume fraction of alkylalkoxysilane used results in a higher density of non-polar / hydrophobic grafted functionalized groups, thus leading to stronger hydrophobicity and reinforcement performance in the final product.

[0078] Example 5, Step 1: Preparation of Weather-Resistant Material. In this example, the preparation of multi-level nano-SiO2 particles, paraffin templates, and amphiphilic Janus SiO2 nanoparticles was not carried out. 0.016 ml of 3-(trihydroxysilyl)propyldimethyloctadecyl ammonium chloride was directly measured and dispersed in 1.7 ml of anhydrous ethanol to prepare a 1% weather-resistant reinforcement material. The percentage is a mass ratio.

[0079] Step 2: Prepare a multifunctional weathering-resistant reinforcement layer using weathering-resistant material. Apply the weathering-resistant material prepared in Step 1 to the surface of a yellow sandstone sample with a surface area of ​​3×3 square centimeters (effective material dosage is 15 g / m²). 2 After the solvent has completely evaporated, the weathering-resistant reinforcement layer is obtained.

[0080] In this embodiment, the preparation of nano-SiO2 particles and amphiphilic Janus SiO2 nanoparticles was not carried out; instead, organosilicon quaternary ammonium salt was used directly as the weathering-resistant material. Because this organosilicon quaternary ammonium salt is pale yellow, the substrate surface has a slight pale yellow tint after coating with the stone substrate. Colorimeter testing showed that the surface color change value ΔE * The surface water contact angle was 6.1, exceeding the upper limit of color change values ​​and failing to meet the requirements for application in cultural relic protection. Surface water contact angle testing showed that the weathering-resistant layer lacked superhydrophobic and self-cleaning functions, with a surface water contact angle exceeding 90°. Scanning electron microscopy revealed a multi-level rough structure at the micro-nano scale, unlike other embodiments. Micro-nano mechanical property testing revealed weak reinforcement performance of the weathering-resistant layer, with the average elastic modulus and hardness of the sandstone sample surface increasing by less than 7%. Antibacterial testing showed that the material possessed antibacterial properties, with an antibacterial efficiency exceeding 88% against *Escherichia coli* and *Staphylococcus aureus* when its concentration was not less than 0.5 g / L. This embodiment illustrates that two fundamental conditions are essential for successfully constructing a superhydrophobic, self-cleaning surface: a multi-level rough structure at the micro-nano scale and a low surface energy material.

[0081] Example 6, Step 1: Preparation of multi-level nano-SiO2 particles. In this example, Step 1 is the same as in Example 3.

[0082] Step 2: Preparation of the weathering-resistant material. In this embodiment, the preparation of paraffin templates and amphiphilic Janus SiO2 nanoparticles was not performed. 14 mg of the multi-level nano-SiO2 particles obtained in Step 1 were directly weighed and dispersed, and then dissolved in 1.8 ml of anhydrous ethanol to prepare a 1% concentration weathering-resistant reinforcement material. The percentage is a mass ratio.

[0083] Step 3: Prepare a multifunctional weathering-resistant reinforcement layer using weathering-resistant material. Apply the weathering-resistant material prepared in Step 2 to the surface of a yellow sandstone sample with a surface area of ​​3×3 square centimeters (effective material dosage is 15 g / m²). 2 After the solvent has completely evaporated, the weathering-resistant reinforcement layer is obtained.

[0084] Since this embodiment directly uses the nanoparticles prepared in step 1, the final weathering-resistant reinforcement layer is made of pure nano-SiO2 particles. As shown in Figure 5, scanning electron microscopy characterization revealed agglomerated nano-SiO2 particles on the surface of the weathering-resistant layer. The surface water contact angle was measured to be only 26.3°±6.5°, indicating that the weathering-resistant layer is hydrophilic. Capillary hydrophobicity testing further confirmed the poor capillary hydrophobic effect of the weathering-resistant layer. Nanoparticle pressure constant testing results showed that the reinforcement effect of this weathering-resistant layer was not significant, with an average increase of approximately 13% in the surface elastic modulus and hardness, lower than other embodiments. This embodiment illustrates that, due to the lack of necessary low surface energy materials, using only nanoparticles with multi-level morphologies cannot construct a superhydrophobic surface. Furthermore, in addition to using nanoparticles to fill some pores in the porous masonry substrate, the in-situ sol-gelation of alkoxysilanes to form a silica gel network that bonds the internal particles is also an important condition for improving the mechanical properties of the substrate.

[0085] The above six embodiments do not represent the limited application scope of this patent. For brick and stone cultural relics with different porosities, mineral compositions and deterioration levels, the concentration and total amount of weathering-resistant materials can be flexibly adjusted to achieve the best superhydrophobic, reinforcement and antibacterial effects.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics, characterized in that, Includes the following steps: An aqueous dispersion of a surfactant was prepared, and an alkaline catalyst was added to obtain an aqueous phase. A silicon source was dispersed in an organic solvent to form an oil phase, which was then added to the aqueous phase. The mixture was stirred at 50-60°C to prepare hierarchical nano-SiO2 particles. The surface hydroxyl groups of the hierarchical nano-SiO2 particles were activated under the action of a strong oxidant. Subsequently, a Pickering emulsion was prepared in a water-paraffin oil two-phase system using the hierarchical nano-SiO2 particles as a solid emulsifier. The emulsion was allowed to stand and cool to solidify the paraffin oil, allowing the SiO2 particles to partially embed into the solid paraffin, thus obtaining a paraffin template. The exposed side of the SiO2 particles in the paraffin template was then reacted with an aminosilane coupling agent to modify the amino group. The paraffin was dissolved and removed using chloroform. The other side was then modified with an alkylalkoxysilane or an organosilicon quaternary ammonium salt, ultimately obtaining amphiphilic Janus SiO2 nanoparticles with one side modified by a polar amino group and the other by a non-polar long-chain alkyl group. The prepared amphiphilic Janus... SiO2 nanoparticles are dispersed in an organic solvent at a mass fraction of 1-5% to obtain an amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics.

2. The preparation method of the amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics according to claim 1, characterized in that, The aminosilane coupling agent is one or more of the following compounds with the following structural formulas: In the formula, R1 is methyl and R2 is ethyl.

3. The preparation method of the amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics according to claim 1, characterized in that, The alkylalkoxysilane has the following structural formula: In the formula, R1, R2, and R3 are methyl or ethyl; the organosilicon quaternary ammonium salt has the following structural formula: In the formula, R is a methyl, ethyl, or hydrogen atom.

4. The preparation method of the amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics according to claim 1, characterized in that, The organic solvent is cyclohexane or anhydrous ethanol; the alkaline catalyst is NaOH; The surface activation of multi-level nano-SiO2 particles is carried out using a strong oxidant, including: pre-treating the surface of the multi-level nano-SiO2 particles in a water bath at 80-85℃ with a strong oxidant to activate the hydroxyl groups on the particle surface; wherein, the strong oxidant is HNO3.

5. The preparation method of the amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics according to claim 1, characterized in that, The multi-level nano-SiO2 particles are virus-like nanoparticles with a particle size of 30-100 nm. These virus-like nanoparticles have a three-dimensional multi-level morphology, with a core diameter of about 30-70 nm and surface needle-like or tubular protrusions with a length of about 5-20 nm.

6. The preparation method of the amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics according to claim 1, characterized in that, When modifying one side of multi-level nano-SiO2 particles with amino groups and the other side with alkylalkoxysilanes or organosilicon quaternary ammonium salts, the reaction is carried out in a water-alcohol composite system with thorough stirring and at 40-50℃.

7. An amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics prepared by the method described in any one of claims 1 to 6.

8. The application of the amphiphilic multi-level nano-SiO2-based anti-weathering and reinforcement material for brick and stone cultural relics as described in claim 7 in the protection and restoration of brick and stone cultural relics.

9. A weathering-resistant reinforcement layer, characterized in that, The amphiphilic multi-level nano-SiO2-based anti-weathering reinforcement material for brick and stone cultural relics as described in claim 7 is uniformly applied to the surface of the brick and stone cultural relics by spraying or brushing. After the solvent has completely evaporated, an anti-weathering reinforcement layer is formed on the surface of the brick and stone cultural relics. The capillary hydrophobic efficiency of the anti-weathering layer formed on the brick and stone substrate with different mineral compositions and porosity of 2%-45% is higher than 90%.

10. The weathering-resistant reinforcement layer according to claim 9, characterized in that, The weathering-resistant reinforcement layer has a water contact angle of 155°-167° and a roll-off angle of 2.8°-6.5°; the mechanical strength of the weathering-resistant reinforcement layer is increased by 23%; when the concentration of the nanocomposite material in the weathering-resistant reinforcement layer is 0.2-1.5 g / L, its antibacterial efficiency against Gram-positive / negative bacteria reaches more than 86%.

Images