A waterproof antibacterial agent for concrete surface and a preparation method thereof

Abstract

The application relates to the technical field of concrete antibacterial technology, and discloses a waterproof antibacterial agent for a concrete surface and a preparation method thereof; the waterproof antibacterial agent comprises modified lignin microspheres, chitosan-Ag@SiO2 powder and a resin base material; the modified lignin microspheres are super-hydrophobic structure-containing microspheres formed by covalent combination of alkyltrichlorosilane and lignin; and the chitosan-Ag@SiO2 powder is silica particles with silver ions deposited and wrapped by chitosan cross-linking. The waterproof antibacterial agent can be applied to concrete and a surface coating thereof; by constructing micro-needle papillae and surface wax crystal modification on a rough surface, the waterproof effect of a super-hydrophobic surface can be achieved; meanwhile, the adhesion of bacteria on the surface of the cement-based material is inhibited, so that good antibacterial performance is achieved.

Description

Technical Field

[0001] This invention relates to the field of antibacterial technology for concrete, and more specifically, to a waterproof and antibacterial agent for concrete surfaces and its preparation method. Background Technology

[0002] Cement-based materials are among the most widely used building materials. After being constructed, they are in contact with moisture and particulate matter in the air for a long time. These substances tend to adhere to the surface of concrete structures and are subject to erosion by rainwater, which eventually damages the surface of the concrete structures. This seriously affects the functionality, durability, and aesthetics of the concrete structures, and also results in high cleaning and maintenance costs.

[0003] During the hydration process, cement generates numerous micropores and defects, and its surface is covered with hydroxyl groups, resulting in strong hydrophilicity. Consequently, moisture on the surface of cement-based materials is easily adsorbed into the interior through capillary action, affecting their performance and durability. This is especially problematic in special environments, such as cold regions where the volume of water increases after freezing, leading to surface peeling or cracking of cement-based materials. In marine environments, the large number of sulfur-oxidizing bacteria present in the water can adhere to the surface of concrete structures, producing acidic metabolic products that cause premature failure of marine concrete. Therefore, improving the waterproof and antibacterial properties of cement-based materials is crucial for enhancing the performance and durability of cement-based structures.

[0004] For example, patent CN113603427A discloses a microbial erosion-resistant protective concrete and its preparation method. The concrete includes cement, coarse aggregate, fine aggregate, micro powder, water, polycarboxylate superplasticizer, corrosion resistant agent, and antibacterial particles. The corrosion resistant agent contains hydroxypropyl chitosan, and the antibacterial particles include silver nitrate, copper nitrate, nano-silica, and polyvinyl alcohol powder. By introducing multiple substances with different functions in a compound formulation, the concrete is given more functional effects.

[0005] However, existing methods of improving concrete by mixing and compounding multiple components, as mentioned above, have limited waterproofing and antibacterial effects in actual use, and their waterproofing and antibacterial properties are unstable and not durable. Summary of the Invention

[0006] The technical problem to be solved by this invention:

[0007] To address the issue that cement-based structures are highly susceptible to cracking or peeling due to erosion from water and acidic substances, the current approach often involves introducing components with strong waterproofing or antibacterial properties into concrete and its additives for compounding. This allows cement-based structures to maintain a certain level of waterproofing and antibacterial performance during use. However, this method suffers from unstable and unsustainable waterproofing and antibacterial properties.

[0008] The technical solution adopted in this invention is as follows:

[0009] This invention provides a waterproof and antibacterial agent for concrete surfaces, comprising modified lignin microspheres, chitosan-Ag@SiO2 powder, and resin base; the modified lignin microspheres are microspheres with a superhydrophobic structure formed by covalent bonding of alkyl trichlorosilane and lignin.

[0010] Preferably, the method for preparing the modified lignin microspheres includes the following steps:

[0011] A1 was used to prepare lignin microspheres;

[0012] A2 placed the lignin microspheres in a solvent, added water, and stirred to disperse them; then added alkyltrichlorosilane, reacted, washed, and dried to obtain the modified lignin microspheres.

[0013] Preferably, the preparation method of step A1 includes the following steps:

[0014] Lignin was placed in an aqueous solution of valerol, and deionized water was added to produce lignin nanospheres. The nanospheres were then dialyzed, centrifuged, and freeze-dried to obtain the lignin nanospheres.

[0015] Preferably, the lignin nanospheres have a particle size of 45-60 nm.

[0016] Preferably, the chitosan-Ag@SiO2 powder is a powder particle with SiO2 as the core material and chitosan as the shell material, and silver ions are deposited on the surface of the chitosan through chelation.

[0017] Preferably, the preparation method of the chitosan-Ag@SiO2 powder includes the following steps:

[0018] B1 prepares an alkaline precursor solution and a reaction base solution containing chitosan, respectively;

[0019] B2 introduces the reaction base liquid into the alkaline precursor solution, stirs, and produces a precipitate; after washing the precipitate, disperses it in distilled water, adds silver nitrate and sodium borohydride, stirs the reaction, washes and dries, and pulverizes to obtain the chitosan-Ag@SiO2 powder.

[0020] Preferably, the alkaline precursor solution comprises ammonia, anhydrous ethanol, and water.

[0021] Preferably, the reaction base liquid includes chitosan, tetraethyl orthosilicate, and ethanol.

[0022] Preferably, the ratio of the modified lignin microspheres to the chitosan-Ag@SiO2 powder by weight is 0.8-2.5:1.

[0023] A method for preparing the above-mentioned waterproof and antibacterial agent for concrete surfaces includes the following steps:

[0024] Modified lignin microspheres and chitosan-Ag@SiO2 powder were added to an organic solvent and dispersed evenly. Then, resin base and curing agent were added under stirring and stirred until homogeneous to obtain the waterproof and antibacterial agent.

[0025] The beneficial effects of this invention are as follows:

[0026] This invention provides protection through a coating layer without altering existing cement-based materials, offering a direct and convenient solution applicable to existing concrete structures. The waterproof and antibacterial agent provided by this invention can be applied to concrete and its surface coatings, effectively enhancing the concrete's resistance to moisture intrusion and improving the structural performance. Specifically, alkyl trichlorosilanes are used to modify lignin, chemically transforming it into a superhydrophobic structure. This is achieved by constructing microneedle-shaped papillae and surface wax crystals on a rough surface, resulting in a waterproof effect on the superhydrophobic surface. Chitosan-Ag@SiO2 powder, with its long-term structural stability, inhibits bacterial adhesion to cement-based material surfaces, thus exhibiting excellent antibacterial properties. Attached Figure Description

[0027] Figure 1 The image shows the morphology of bacteria on the culture medium treated with the waterproof and antibacterial agent described in Example 2.

[0028] Figure 2 The image shows the morphology of bacteria on the culture medium treated with the waterproof and antibacterial agent in Example 3.

[0029] Figure 3 The image shows the morphology of bacteria on the culture medium treated with the waterproof and antibacterial agent in Example 5.

[0030] Figure 4 The image shows the morphology of bacteria on the culture medium treated with the waterproof and antibacterial agent described in Example 6.

[0031] Figure 5 The image shows the bacterial morphology of a culture medium that was not treated with the waterproof and antibacterial agent of this invention.

[0032] Figure 6 The image shows the bacterial morphology of a cement-based material block treated with the waterproof and antibacterial agent described in Example 2.

[0033] Figure 7 The image shows the bacterial morphology of a cement-based material block treated with the waterproof and antibacterial agent described in Example 3.

[0034] Figure 8 A diagram showing the bacterial morphology of a cement-based material block treated with the waterproof and antibacterial agent described in Example 5.

[0035] Figure 9 A diagram showing the bacterial morphology of a cement-based material block treated with the waterproof and antibacterial agent described in Example 6.

[0036] Figure 10 The image shows the bacterial morphology of a cement-based material block that was not treated with the waterproof and antibacterial agent described in this invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0038] This invention provides a waterproof and antibacterial agent for concrete surfaces, the raw materials of which include: epoxy resin, curing agent, modified lignin microspheres and chitosan-Ag@SiO2 powder, wherein the epoxy resin is used as the matrix material and the curing agent can be selected from diethylenetriamine, etc.

[0039] The method for preparing modified lignin microspheres in this invention includes the following steps:

[0040] (1) Dissolve lignin in an aqueous solution of valerol and then rapidly inject deionized water to produce lignin nanospheres with an average diameter of 45-60 nm; pack the lignin nanospheres into a dialysis bag, dialyze for 5-8 days, centrifuge, freeze dry for 10-15 h to obtain lignin microspheres.

[0041] (2) Place the lignin microspheres in anhydrous ethanol, disperse them, add deionized water, stir at high speed for 20-45 min, then add alkyltrichlorosilane, react for about 1-3 h, then wash the product obtained from the reaction three times with anhydrous ethanol to remove residual alkyltrichlorosilane and other modified impurities, and place it in a vacuum dryer at 50-80℃ for 10-15 h to obtain hydrophobic modified lignin microspheres.

[0042] Alkyltrichlorosilanes may be selected from methyltrichlorosilane and / or ethyltrichlorosilane, etc.

[0043] In this invention, alkyltrichlorosilane is used to modify lignin to form a superhydrophobic structure through chemical modification. The chemical modification process is shown in the following reaction formula (1):

[0044] Chemical formula (1).

[0045] The preparation method of chitosan-Ag@SiO2 powder in this invention includes the following steps:

[0046] (1) Mix concentrated ammonia, anhydrous ethanol and pure water, and mechanically stir for 3-15 min to obtain an alkaline precursor solution; separately prepare a mixture of tetraethyl orthosilicate and ethanol, add chitosan, and ultrasonically disperse for 5-20 min to ensure that chitosan is uniformly dispersed in the mixture to obtain the reaction base solution.

[0047] (2) Quickly pour the reaction base liquid into the alkaline precursor solution and stir at a speed of 600-800 r / min for 2-5 h to form chitosan@SiO2 precipitate. Disperse the chitosan@SiO2 precipitate in distilled water and wash it alternately with anhydrous ethanol and distilled water. Then disperse the chitosan@SiO2 precipitate in distilled water, add silver nitrate, stir evenly, add a trace amount of sodium borohydride solution, stir, wash, dry, and pulverize to obtain chitosan-Ag@SiO2 powder.

[0048] In this invention, chitosan in chitosan-Ag@SiO2 powder serves as an intermediate. On the one hand, it can effectively encapsulate silicon dioxide, and on the other hand, it can chelate with silver ions, making its structural connection more stable, thereby making the waterproof and antibacterial agent more effective.

[0049] This invention also provides a method for preparing a waterproof and antibacterial agent for concrete surfaces, comprising the following steps:

[0050] Modified lignin microspheres and chitosan-Ag@SiO2 powder were added to anhydrous ethanol at a mass ratio of 0.8-2.5:1, ultrasonically dispersed, stirred, and epoxy resin and curing agent were added while stirring. The mixture was stirred until it was homogeneous to obtain a waterproof and antibacterial agent.

[0051] Example 1

[0052] Step 1: In a three-necked flask, add 18 mL of 28% concentrated ammonia, 32 mL of anhydrous ethanol, and 50 mL of pure water sequentially. Mix and stir for 5 min to obtain an alkaline precursor solution. Separately, prepare a 100 mL mixture of tetraethyl orthosilicate and ethanol at a volume ratio of 9:91, add 0.5 g of chitosan, sonicate for 10 min, and then quickly pour it into the three-necked flask containing the alkaline precursor solution. Stir continuously at 600 r / min for 3 h, and then wash three times alternately with anhydrous ethanol and distilled water. Disperse the obtained precipitate in distilled water, add 0.2 g of silver nitrate, stir evenly, add a trace amount of sodium borohydride solution, wash and dry to obtain chitosan-Ag@SiO2 powder.

[0053] Step 2: Dissolve 40 mg of lignin in 2 mL of 90% (v / v) valerate-lactone aqueous solution, then rapidly inject deionized water to produce lignin nanospheres with an average diameter of approximately 55 nm. Place the lignin nanospheres in a dialysis bag and dialyze for 7 days. Centrifuge and freeze-dry for 12 hours to obtain lignin microspheres. Disperse the lignin microspheres in 100 mL of anhydrous ethanol, add 0.5 mL of deionized water, stir rapidly for 30 min, then add 0.15 g of methyltrichlorosilane and react for 2 hours. Wash the reaction product three times with anhydrous ethanol and then vacuum dry at 60 °C for 12 hours to obtain modified lignin microspheres.

[0054] Step 3: Mix chitosan-Ag@SiO2 powder and modified lignin microspheres at a mass ratio of 1:1 in anhydrous ethanol, ultrasonically disperse for 30 minutes, stir for 50 minutes, then add 7g epoxy resin and 0.07g diethylenetriamine, continue stirring until uniformly mixed to obtain a waterproof and antibacterial agent.

[0055] Example 2

[0056] Step 1: In a three-necked flask, add 18 mL of 28% concentrated ammonia, 32 mL of anhydrous ethanol, and 50 mL of pure water sequentially. Mix and stir for 5 min to obtain an alkaline precursor solution. Separately, prepare a 100 mL mixture of tetraethyl orthosilicate and ethanol at a volume ratio of 9:91, add 0.5 g of chitosan to the mixture, sonicate for 10 min, and then quickly pour the mixture into the three-necked flask containing the alkaline precursor solution. Stir continuously at 600 r / min for 3 h, and then wash three times alternately with anhydrous ethanol and distilled water. Disperse the obtained precipitate in distilled water, add 0.3 g of silver nitrate, stir evenly, add a trace amount of sodium borohydride solution, wash and dry to obtain chitosan-Ag@SiO2 powder.

[0057] Step 2: Dissolve 40 mg of lignin in 2 mL of 90% (v / v) valerate-lactone aqueous solution, then rapidly inject deionized water to produce lignin nanospheres with an average diameter of approximately 55 nm. Place the lignin nanospheres in a dialysis bag and dialyze for 7 days. Centrifuge and freeze-dry for 12 hours to obtain lignin microspheres. Disperse the lignin microspheres in 100 mL of anhydrous ethanol, add 0.5 mL of deionized water, stir rapidly for 30 min, then add 0.30 g of methyltrichlorosilane and react for 2 hours. Wash the reaction product three times with anhydrous ethanol and then vacuum dry at 60 °C for 12 hours to obtain modified lignin microspheres.

[0058] Step 3: Mix chitosan-Ag@SiO2 powder and modified lignin microspheres at a mass ratio of 1:1 in anhydrous ethanol, ultrasonically disperse for 30 minutes, stir for 50 minutes, then add 7g epoxy resin and 0.07g diethylenetriamine, continue stirring until uniformly mixed to obtain a waterproof and antibacterial agent.

[0059] Example 3

[0060] Step 1: In a three-necked flask, add 18 mL of 28% concentrated ammonia, 32 mL of anhydrous ethanol, and 50 mL of pure water sequentially. Mix and stir for 5 min to obtain an alkaline precursor solution. Separately, prepare a 100 mL mixture of tetraethyl orthosilicate and ethanol at a volume ratio of 9:91, add 0.5 g of chitosan to the mixture, sonicate for 10 min, and then quickly pour the mixture into the three-necked flask containing the alkaline precursor solution. Stir continuously at 600 r / min for 3 h, and then wash three times alternately with anhydrous ethanol and distilled water. Disperse the obtained precipitate in distilled water, add 0.3 g of silver nitrate, stir evenly, add a trace amount of sodium borohydride solution, wash and dry to obtain chitosan-Ag@SiO2 powder.

[0061] Step 2: Dissolve 40 mg of lignin in 2 mL of 90% (v / v) valerate-lactone aqueous solution, then rapidly inject deionized water to produce lignin nanospheres with an average diameter of approximately 55 nm. Place the lignin nanospheres in a dialysis bag and dialyze for 7 days. Centrifuge and freeze-dry for 12 hours to obtain lignin microspheres. Disperse the lignin microspheres in 100 mL of anhydrous ethanol, add 0.5 mL of deionized water, stir rapidly for 30 min, then add 0.30 g of methyltrichlorosilane and react for 2 hours. Wash the reaction product three times with anhydrous ethanol and then vacuum dry at 60 °C for 12 hours to obtain modified lignin microspheres.

[0062] Step 3: Mix chitosan-Ag@SiO2 powder and modified lignin microspheres at a mass ratio of 2:1 in anhydrous ethanol, ultrasonically disperse for 30 minutes, stir for 50 minutes, then add 7g epoxy resin and 0.07g diethylenetriamine, continue stirring until uniformly mixed to obtain a waterproof and antibacterial agent.

[0063] Example 4

[0064] Step 1: In a three-necked flask, add 18 mL of 28% concentrated ammonia, 32 mL of anhydrous ethanol, and 50 mL of pure water sequentially. Mix and stir for 5 min to obtain an alkaline precursor solution. Separately, prepare a 100 mL mixture of tetraethyl orthosilicate and ethanol at a volume ratio of 9:91, add 0.5 g of chitosan, sonicate for 10 min, and then quickly pour it into the three-necked flask containing the alkaline precursor solution. Stir continuously at 600 r / min for 3 h, and then wash three times alternately with anhydrous ethanol and distilled water. Disperse the obtained precipitate in distilled water, add 0.2 g of silver nitrate, stir evenly, add a trace amount of sodium borohydride solution, wash and dry to obtain chitosan-Ag@SiO2 powder.

[0065] Step 2: Dissolve 40 mg of lignin in 2 mL of 90% (v / v) valerate-lactone aqueous solution, then rapidly inject deionized water to produce lignin nanospheres with an average diameter of approximately 55 nm. Place the lignin nanospheres in a dialysis bag and dialyze for 7 days. Centrifuge and freeze-dry for 12 hours to obtain lignin microspheres. Disperse the lignin microspheres in 100 mL of anhydrous ethanol, add 0.5 mL of deionized water, stir rapidly for 30 min, then add 0.15 g of ethyltrichlorosilane and react for 2 hours. Wash the reaction product three times with anhydrous ethanol and then vacuum dry at 60 °C for 12 hours to obtain modified lignin microspheres.

[0066] Step 3: Mix chitosan-Ag@SiO2 powder and modified lignin microspheres at a mass ratio of 1:1 in anhydrous ethanol, ultrasonically disperse for 30 minutes, stir for 50 minutes, then add 7g epoxy resin and 0.07g diethylenetriamine, continue stirring until uniformly mixed to obtain a waterproof and antibacterial agent.

[0067] Example 5

[0068] Step 1: In a three-necked flask, add 18 mL of 28% concentrated ammonia, 32 mL of anhydrous ethanol, and 50 mL of pure water sequentially. Mix and stir for 5 min to obtain an alkaline precursor solution. Separately, prepare a 100 mL mixture of tetraethyl orthosilicate and ethanol at a volume ratio of 9:91, add 0.3 g of chitosan to the mixture, sonicate for 10 min, and then quickly pour the mixture into the three-necked flask containing the alkaline precursor solution. Stir continuously at 600 r / min for 3 h, and then wash three times alternately with anhydrous ethanol and distilled water. Disperse the obtained precipitate in distilled water, add 0.2 g of silver nitrate, stir evenly, add a trace amount of sodium borohydride solution, wash and dry to obtain chitosan-Ag@SiO2 powder.

[0069] Step 2: Dissolve 40 mg of lignin in 2 mL of 90% (v / v) valerate-lactone aqueous solution, then rapidly inject deionized water to produce lignin nanospheres with an average diameter of approximately 55 nm. Place the lignin nanospheres in a dialysis bag and dialyze for 7 days. Centrifuge and freeze-dry for 12 hours to obtain lignin microspheres. Disperse the lignin microspheres in 100 mL of anhydrous ethanol, add 0.5 mL of deionized water, stir rapidly for 30 min, then add 0.15 g of ethyltrichlorosilane and react for 2 hours. Wash the reaction product three times with anhydrous ethanol and then vacuum dry at 60 °C for 12 hours to obtain modified lignin microspheres.

[0070] Step 3: Mix chitosan-Ag@SiO2 powder and modified lignin microspheres at a mass ratio of 1:1 in anhydrous ethanol, ultrasonically disperse for 30 minutes, stir for 50 minutes, then add 7g epoxy resin and 0.07g diethylenetriamine, continue stirring until uniformly mixed to obtain a waterproof and antibacterial agent.

[0071] Example 6

[0072] Step 1: In a three-necked flask, add 18 mL of 28% concentrated ammonia, 32 mL of anhydrous ethanol, and 50 mL of pure water sequentially. Mix and stir for 5 min to obtain an alkaline precursor solution. Separately, prepare a 100 mL mixture of tetraethyl orthosilicate and ethanol at a volume ratio of 9:91, add 0.5 g of chitosan to the mixture, sonicate for 10 min, and then quickly pour the mixture into the three-necked flask containing the alkaline precursor solution. Stir continuously at 600 r / min for 3 h, and then wash three times alternately with anhydrous ethanol and distilled water. Disperse the obtained precipitate in distilled water, add 0.3 g of silver nitrate, stir evenly, add a trace amount of sodium borohydride solution, wash and dry to obtain chitosan-Ag@SiO2 powder.

[0073] Step 2: Dissolve 40 mg of lignin in 2 mL of 90% (v / v) valerate-lactone aqueous solution, then rapidly inject deionized water to produce lignin nanospheres with an average diameter of approximately 55 nm. Place the lignin nanospheres in a dialysis bag and dialyze for 7 days. Centrifuge and freeze-dry for 12 hours to obtain lignin microspheres. Disperse the lignin microspheres in 100 mL of anhydrous ethanol, add 0.5 mL of deionized water, stir rapidly for 30 min, then add 0.30 g of methyltrichlorosilane and react for 2 hours. Wash the reaction product three times with anhydrous ethanol and then vacuum dry at 60 °C for 12 hours to obtain modified lignin microspheres.

[0074] Step 3: Mix chitosan-Ag@SiO2 powder and modified lignin microspheres at a mass ratio of 2:1 in anhydrous ethanol, ultrasonically disperse for 30 minutes, stir for 50 minutes, then add 7g epoxy resin and 0.07g diethylenetriamine, continue stirring until uniformly mixed to obtain a waterproof and antibacterial agent.

[0075] Comparative Example 1

[0076] Step 2: Dissolve 40 mg of lignin in 2 mL of 90% (v / v) valerate-lactone aqueous solution, then rapidly inject deionized water to produce lignin nanospheres with an average diameter of approximately 55 nm. Place the lignin nanospheres in a dialysis bag and dialyze for 7 days. Centrifuge and freeze-dry for 12 hours to obtain lignin microspheres. Disperse the lignin microspheres in 100 mL of anhydrous ethanol, add 0.5 mL of deionized water, stir rapidly for 30 min, then add 0.15 g of methyltrichlorosilane and react for 2 hours. Wash the reaction product three times with anhydrous ethanol and then vacuum dry at 60 °C for 12 hours to obtain modified lignin microspheres.

[0077] Step 2: Mix 0.5g chitosan, 0.15g silver nitrate, and 2.6g silica. Take an equal mass of modified lignin microspheres and place them together in anhydrous ethanol. Disperse by ultrasonication for 30 minutes and stir for 50 minutes. Then add 7g epoxy resin and 0.07g diethylenetriamine and continue stirring until the mixture is homogeneous to obtain a waterproof and antibacterial agent.

[0078] Comparative Example 2

[0079] Step 2: Dissolve 40 mg of lignin in 2 mL of 90% (v / v) valerate-lactone aqueous solution, then rapidly inject deionized water to produce lignin nanospheres with an average diameter of approximately 55 nm. Place the lignin nanospheres in a dialysis bag and dialyze for 7 days. Centrifuge and freeze-dry for 12 hours to obtain lignin microspheres. Disperse the lignin microspheres in 100 mL of anhydrous ethanol, add 0.5 mL of deionized water, stir rapidly for 30 min, then add 0.15 g of methyltrichlorosilane and react for 2 hours. Wash the reaction product three times with anhydrous ethanol and then vacuum dry at 60 °C for 12 hours to obtain modified lignin microspheres.

[0080] Step 2: Place approximately 3.4g of modified lignin microspheres in anhydrous ethanol, ultrasonically disperse for 30min, and stir for 50min. Then add 7g of epoxy resin and 0.07g of diethylenetriamine, and continue stirring until the mixture is homogeneous to obtain a waterproof and antibacterial agent.

[0081] Comparative Example 3

[0082] Step 1: In a three-necked flask, add 18 mL of 28% concentrated ammonia, 32 mL of anhydrous ethanol, and 50 mL of pure water sequentially. Mix and stir for 5 min to obtain an alkaline precursor solution. Separately, prepare a 100 mL mixture of tetraethyl orthosilicate and ethanol at a volume ratio of 9:91, add 0.5 g of chitosan, sonicate for 10 min, and then quickly pour it into the three-necked flask containing the alkaline precursor solution. Stir continuously at 600 r / min for 3 h, and then wash three times alternately with anhydrous ethanol and distilled water. Disperse the obtained precipitate in distilled water, add 0.2 g of silver nitrate, stir evenly, add a trace amount of sodium borohydride solution, wash and dry to obtain chitosan-Ag@SiO2 powder.

[0083] Step 2: Take 40 mg of lignin and dissolve it in 2 mL of 90% (v / v) valerate aqueous solution. Then, quickly inject deionized water to produce lignin nanospheres with an average diameter of about 55 nm. Place the lignin nanospheres in a dialysis bag and dialyze for 7 days. Centrifuge and freeze-dry for 12 hours to obtain lignin microspheres.

[0084] Step 3: Mix chitosan-Ag@SiO2 powder and lignin microspheres at a mass ratio of 1:1 in anhydrous ethanol, ultrasonically disperse for 30 minutes, stir for 50 minutes, then add 7g of epoxy resin and 0.07g of diethylenetriamine, continue stirring until uniformly mixed to obtain a waterproof and antibacterial agent.

[0085] Comparative Example 4

[0086] Step 1: In a three-necked flask, add 18 mL of 28% concentrated ammonia, 32 mL of anhydrous ethanol, and 50 mL of pure water sequentially. Mix and stir for 5 min to obtain an alkaline precursor solution. Separately, prepare a 100 mL mixture of tetraethyl orthosilicate and ethanol at a volume ratio of 9:91, add 0.5 g of chitosan, sonicate for 10 min, and then quickly pour it into the three-necked flask containing the alkaline precursor solution. Stir continuously at 600 r / min for 3 h, and then wash three times alternately with anhydrous ethanol and distilled water. Disperse the obtained precipitate in distilled water, add 0.2 g of silver nitrate, stir evenly, add a trace amount of sodium borohydride solution, wash and dry to obtain chitosan-Ag@SiO2 powder.

[0087] Step 2: Place the above chitosan-Ag@SiO2 powder in anhydrous ethanol, ultrasonically disperse for 30 minutes, stir for 50 minutes, then add 7g of epoxy resin and 0.07g of diethylenetriamine, continue stirring and mix evenly to obtain a waterproof and antibacterial agent.

[0088] <Experimental Example>

[0089] Samples: Examples 1-6, Comparative Examples 1-4

[0090] Take multiple cement-based material blocks and apply the waterproof and antibacterial agents from Examples 1-6 and Comparative Examples 1-4 to their surfaces twice, with each application amounting to 600 g / m². 2 The two coatings were applied 3 hours apart. The next coating was applied only after the waterproof and antibacterial agent had been completely absorbed and dried. After coating, the surface was cleaned with a soft brush. The cement-based material blocks coated with the waterproof and antibacterial agent were then subjected to the following tests:

[0091] (1) Waterproof performance test

[0092] The contact angles at different locations on the surface of the treated cement-based material block were measured using a static contact angle meter. The static contact angles were measured using the pendant drop method. The average value of measurements taken from five regions was used as the test result. The test results are shown in Table 1 below:

[0093] Table 1. Contact angle test results for different samples

[0094] Example 1 158.58 Example 2 163.83 Example 3 163.61 Example 4 156.16 Example 5 158.77 Example 6 158.68 Comparative Example 1 153.12 Comparative Example 2 150.74 Comparative Example 3 147.96 Comparative Example 4 148.50

[0095] As shown in Table 1, after the surface of the cement-based material block is coated with the waterproof and antibacterial agents of Examples 1 to 6 to form a coating, the contact angle of the surface is significantly larger than that of the cement-based material block treated with the waterproof and antibacterial agents of Comparative Examples 1 to 4. This indicates that the waterproof and antibacterial agent of the present invention can give the surface of the cement-based material a good waterproof effect.

[0096] (2) Antibacterial properties and antibacterial adhesion properties test

[0097] Take 200 μL of undiluted compound bacterial suspension with Bacillus as the dominant bacteria and inoculate it into multiple culture media. Then, add 0, 100 μL of the waterproof and antibacterial agent from Example 2, 100 μL of the waterproof and antibacterial agent from Example 3, 100 μL of the waterproof and antibacterial agent from Example 5, and 100 μL of the waterproof and antibacterial agent from Example 6 in sequence. The media without added liquids serve as blank controls. Place the above culture media in a constant temperature incubator and incubate for 48 h. After removal, observe the bacterial growth. Place the blank cement-based material block and the cement-based material block treated with the waterproof and antibacterial agent into a compound bacterial solution with Bacillus as the dominant bacteria and incubate for 15 days. After 15 days, remove the material and wash the surface with sterile saline to remove any bacteria that have not adhered to it. Observe the bacterial condition on the surface of the material.

[0098] like Figures 1 to 4 The images show bacterial morphology diagrams of the culture dishes after treatment using Examples 2, 3, 5, and 6, respectively. Figure 5 Images of bacterial morphology on culture dishes not treated with the waterproof and antibacterial agent of this invention; such as Figures 6 to 9 The images show the bacterial morphology on the surface of cement-based material blocks treated according to Examples 2, 3, 5, and 6, respectively. Figure 10 The image shows the bacterial morphology on the surface of a cement-based material block that was not treated with the waterproof and antibacterial agent of this invention.

[0099] The comparison revealed that the bacteria count in the culture medium treated with the waterproof and antibacterial agent was significantly lower. Furthermore, the surface of the cement-based material block without the waterproof and antibacterial agent treatment showed obvious biofilm adhesion, while the surface of the cement-based material block coated with the waterproof and antibacterial agent showed no obvious signs of bacterial growth. This indicates that the waterproof and antibacterial agent of the present invention can effectively inhibit bacterial growth in cement-based materials, exhibiting good antibacterial and anti-adhesion properties. The antibacterial effects of Examples 3 and 6, which have high chitosan and Ag content, are even more significant.

[0100] In summary, the waterproof and antibacterial agents prepared in Examples 1 to 6 not only exhibit outstanding advantages in waterproof performance, achieving significant hydrophobic and waterproof effects by forming a superhydrophobic structure on the surface of cement-based material blocks, but also demonstrate effective antibacterial and antimicrobial adhesion properties. This demonstrates that the waterproof and antibacterial agent provided by this invention can indeed exert good waterproof and antibacterial effects, and its effects are significant and stable.

[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A waterproof and antibacterial agent for concrete surfaces, characterized in that, Including modified lignin microspheres, chitosan-Ag@SiO2 powder, and resin matrix; The modified lignin microspheres are microspheres with a superhydrophobic structure formed by covalent bonding of alkyl trichlorosilane and lignin. The chitosan-Ag@SiO2 powder is a powder particle with SiO2 as the core material and chitosan as the shell material, and silver ions are deposited on the surface of chitosan through chelation.

2. The waterproof and antibacterial agent for concrete surfaces according to claim 1, characterized in that, The method for preparing the modified lignin microspheres includes the following steps: A1 Preparation of lignin microspheres; A2. The lignin microspheres were placed in a solvent, water was added, and the mixture was stirred and dispersed. Then, alkyltrichlorosilane was added, the mixture was reacted, washed, and dried to obtain the modified lignin microspheres.

3. The waterproof and antibacterial agent for concrete surfaces according to claim 2, characterized in that, The preparation method of step A1 includes the following steps: Lignin was placed in an aqueous solution of valerol, and deionized water was added to produce lignin nanospheres. The nanospheres were then dialyzed, centrifuged, and freeze-dried to obtain the lignin nanospheres.

4. The waterproof and antibacterial agent for concrete surfaces according to claim 3, characterized in that, The lignin nanospheres have a particle size of 45-60 nm.

5. The waterproof and antibacterial agent for concrete surfaces according to claim 1, characterized in that, The preparation method of the chitosan-Ag@SiO2 powder includes the following steps: B1 Prepare an alkaline precursor solution and a reaction base solution containing chitosan, respectively; B2 The reaction base solution is introduced into an alkaline precursor solution and stirred to produce a precipitate. After washing the precipitate, it is dispersed in distilled water, silver nitrate and sodium borohydride are added, the mixture is stirred to react, washed and dried, and then powdered to obtain the chitosan-Ag@SiO2 powder.

6. The waterproof and antibacterial agent for concrete surfaces according to claim 1, characterized in that, The alkaline precursor solution includes ammonia, anhydrous ethanol, and water.

7. The waterproof and antibacterial agent for concrete surfaces according to claim 1, characterized in that, The reaction base liquid includes chitosan, tetraethyl orthosilicate, and ethanol.

8. The waterproof and antibacterial agent for concrete surfaces according to claim 1, characterized in that, The ratio of the modified lignin microspheres to the chitosan-Ag@SiO2 powder by weight is 0.8-2.5:

1.

9. A method for preparing a waterproof and antibacterial agent for concrete surfaces according to any one of claims 1 to 8, characterized in that, The steps include the following: Modified lignin microspheres and chitosan-Ag@SiO2 powder were added to an organic solvent and dispersed evenly. Then, resin base and curing agent were added under stirring and stirred until homogeneous to obtain the waterproof and antibacterial agent.

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