A multifunctional superwetting material with pH responsiveness and its preparation method and application

Abstract

The present invention discloses a method for preparing a multifunctional super-wetting material with pH responsiveness, comprising: (1) simultaneously adding tetraethyl orthosilicate and a mercaptosilane coupling agent to an ethanol solution containing aqueous ammonia, and obtaining mercapto-modified silica particles after complete reaction at room temperature; (2) mixing the mercapto-modified silica particles, an unsaturated fatty acid, a photoinitiator, and a solvent A, and preparing silica particles with pH responsiveness after a mercapto-ene click reaction initiated by ultraviolet light; and (3) blending the silica particles with pH responsiveness, an adhesive, and a solvent B, and applying the mixture to the surface and interior of a substrate to obtain a multifunctional super-wetting material with pH responsiveness. The preparation process of the present invention is simple, the raw materials are widely available, the water contact angle of the prepared product is greater than 150°, and the product has the advantages of fast pH response speed and high stability. The product can be used to remove heavy metal ions and organic dyes from water bodies, and is used in various scenarios such as oil-water separation.

Description

Technical Field

[0001] The present invention relates to the technical field of responsive superwetting materials, and in particular to a multifunctional superwetting material with pH responsiveness, a preparation method thereof, and applications thereof. Background Art

[0002] Water is a vital resource for human survival and development. With rapid economic growth, booming industrial production and processing activities, such as fossil fuel extraction, printing and dyeing, and papermaking, have generated large amounts of oily wastewater, exacerbating the current severe water shortage situation. Recently, various approaches have been explored to achieve efficient oil-water separation. Traditional superhydrophobic "oil removal" and superhydrophilic "water removal" oil-water separation materials can only separate simple heavy oil / water or light oil / water mixtures, failing to meet the increasingly complex demands of oil-water separation. In recent years, stimuli-responsive smart oil-water separation materials have attracted widespread attention due to their excellent performance in separating a variety of oil-water mixtures. Stimuli-responsive smart materials for oil-water separation typically refer to materials whose surface wettability can cycle between superhydrophobic and superhydrophilic states in response to stimuli such as light, heat, magnetism, electricity, or pH. However, it is important to note that to ensure stable stimulus transmission and successful response, the light, heat, magnetism, or electricity stimuli often require certain physical properties of the substrate.

[0003] Smart materials with surface wettability changes triggered by pH have received great attention due to their ease of operation and versatility of substrates. Although people have made great efforts to improve super-wetting materials with pH responsiveness, in order to obtain the rough morphology and low surface energy required for special wettability, most of them use laborious, time-consuming or low-atom utilization preparation methods, which are not suitable for large-scale industrial production. For example, the patent applications with publication numbers CN 112981973 A, CN 107326652A, CN 106243271A, CN 111041835A, and CN 111893766A all design and modify polymers to prepare new polymers with pH responsiveness. In order to reduce the viscosity of the system, enhance the heat transfer efficiency and avoid the gel effect, the commonly used free radical solution polymerization not only produces a large amount of organic waste liquid, but also requires heating the reaction system for several hours or even dozens of hours to obtain the final product, which is undoubtedly inefficient and energy-intensive. In addition, in order to improve the bonding ability between the coating and the substrate, these polymers often introduce siloxane groups into their structures. However, the pH-responsive groups (such as carboxyl groups, amino groups, etc.) carried by the polymers themselves will catalyze the hydrolysis and condensation of the siloxane groups. Therefore, the storage stability of the product needs to be considered.

[0004] To address these issues, researchers have attempted to directly chemically modify the particle surface to synthesize pH-responsive particles. Compared to polymers, particles are not restricted by substrate and can be easily deposited or loaded onto a variety of substrates. Currently, most particle surface chemical modification methods involve hydrolysis and condensation of silane coupling agents with pH-responsive groups on the silica surface (Journal of Colloid and Interface Science 557(2019)65–75, Journal of Colloid and Interface Science 575(2020)231–244, CN 113578190A). However, the hydrolysis and condensation process of silane coupling agents is slow, resulting in a low final modification yield and requiring the addition of additional raw materials such as long-chain silane coupling agents to enhance the hydrophobicity of the particles. These methods only involve surface chemical modification and lack effective control over particle morphology.

[0005] Furthermore, the use of biologically and environmentally harmful raw materials, such as heavy metal ions like gold, silver, and copper, and perfluoroalkyl compounds, not only increases manufacturing costs but also flops the requirements of green chemistry and sustainable development. Furthermore, oily wastewater generated by industrial production activities is often contaminated with significant amounts of heavy metal ions and other organic pollutants, a finding that, to our knowledge, has been rarely addressed in previous studies. To minimize the ecological impact of oily wastewater and to recover precious water resources, developing a flexible oil-water separation strategy using environmentally friendly methods and materials that can meet increasingly complex separation requirements remains challenging. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention discloses a method for simply manufacturing a multifunctional super-wetting material with pH responsiveness. The raw materials are widely available and the preparation process is simple. The water contact angle of the prepared product is higher than 150°, and it has the advantages of fast pH response speed and high stability. It can be used for removing heavy metal ions and organic dyes from water bodies, as well as for various application scenarios such as oil-water separation.

[0007] The specific technical solutions are as follows:

[0008] A method for preparing a multifunctional super-wetting material with pH responsiveness comprises the following steps:

[0009] (1) Tetraethyl orthosilicate and a mercaptosilane coupling agent are added simultaneously to an ethanol solution containing aqueous ammonia, and the reaction is completed at room temperature to obtain mercapto-modified silica particles;

[0010] (2) mixing the thiol-modified silica particles prepared in step (1), unsaturated fatty acids, a photoinitiator, and solvent A, and subjecting the mixture to a thiol-ene click reaction initiated by ultraviolet light to prepare pH-responsive silica particles;

[0011] (3) The pH-responsive silica particles prepared in step (2), an adhesive, and a solvent B are mixed and coated on the surface and interior of the substrate to obtain the pH-responsive multifunctional super-wetting material.

[0012] The preparation method disclosed in the present invention uses tetraethyl orthosilicate and mercaptosilane coupling agent as raw materials, and then through an efficient and mild mercapto-ene click reaction, natural unsaturated fatty acids are grafted onto the surface of silica particles, thereby obtaining silica particles with pH responsiveness, and then a coating process is used to obtain a multifunctional super-wetting material with pH responsiveness. The key to this preparation method is that tetraethyl orthosilicate and mercaptosilane coupling agent need to be added at the same time. Only under this process can mercapto-modified silica particles with a multi-level hierarchical structure be prepared, and this morphological structure is the prerequisite for the subsequent acquisition of a multifunctional super-wetting material with pH responsiveness; experiments have found that if tetraethyl orthosilicate and mercaptosilane coupling agent are added step by step, although silica particles with a spherical morphology can still be prepared, the multi-level hierarchical structure disappears; if only mercaptosilane coupling agent is added to the raw material system, the prepared silica particles will no longer have a spherical morphology.

[0013] In step (1):

[0014] The mercaptosilane coupling agent is selected from one or more of mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, mercaptopropylmethyldimethoxysilane, and 3-mercaptopropyltributoxysilane;

[0015] The molar ratio of tetraethyl orthosilicate to mercaptosilane coupling agent is 1 to 10:1;

[0016] In the ethanol solution, the total concentration of tetraethyl orthosilicate and mercaptosilane coupling agent is 0.04-0.15 mL / g, and the mass concentration of ammonia water is 0.05-0.2 g / g.

[0017] Preferably,

[0018] The molar ratio of tetraethyl orthosilicate to mercaptosilane coupling agent is 1 to 6:1;

[0019] In the ethanol solution, the total concentration of tetraethyl orthosilicate and mercaptosilane coupling agent is 0.08-0.15 mL / g, and the mass concentration of ammonia water is 0.08-0.15 g / g.

[0020] In step (2):

[0021] The unsaturated fatty acid is selected from one or more of linoleic acid, oleic acid, erucic acid, linolenic acid, arachidonic acid, nervonic acid, 10-hydroxy-2-decenoic acid, myristic acid, palmitoleic acid, ricinoleic acid, eicosapentaenoic acid, and docosahexaenoic acid;

[0022] The photoinitiator is selected from one or more of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphosphonic acid ethyl ester, 2-methyl-1-[4-methylthiophenyl]-2-morpholinyl-1-propanone, 2-isopropylthioxanthone, 4-dimethylamino-ethyl benzoate, benzoin dimethyl ether, methyl o-benzoylbenzoate, 4-phenylbenzophenone, and 4-chlorobenzophenone;

[0023] The solvent A is selected from one or more of ethanol, tetrahydrofuran, ether, dichloromethane, chloroform and methanol.

[0024] Preferred:

[0025] The mass ratio of the thiol-modified silica particles to the unsaturated fatty acid is 1:0.5 to 2.0; more preferably, the mass ratio of the thiol-modified silica particles to the unsaturated fatty acid is 1:0.6 to 1.7;

[0026] The mass concentration of the thiol-modified silica particles in the solvent is 0.03 to 0.2 g / g; more preferably, the mass concentration of the thiol-modified silica particles in the solvent is 0.08 to 0.1 g / g;

[0027] In step (3):

[0028] The adhesive is selected from one or more of urea-formaldehyde resin, polyvinyl acetate resin, polyacrylic acid resin, polyacrylic acid resin, polyurethane, epoxy resin, and silicone;

[0029] Preferred:

[0030] The mass ratio of the pH-responsive silica particles to the adhesive is 1:0.3 to 5.0, and more preferably 1:0.5 to 2.0.

[0031] Solvent B is selected from one or more of ethyl acetate, acetone, and water;

[0032] Preferably, the mass concentration of the pH-responsive silica particles in solvent B is 0.01 to 0.5 g / g, and more preferably 0.05 to 0.2 g / g.

[0033] The coating includes spray coating or dipping coating;

[0034] The substrate has a porous structure and is selected from fabric, sponge, foam copper or aerogel;

[0035] Preferably, the substrate is selected from sponge, copper foam or aerogel; experiments have found that using the above-mentioned substrate with a higher specific surface area can achieve a higher loading amount of pH-responsive silica particles and obtain better performance, including a shorter pH response time.

[0036] The invention also discloses a multifunctional super-wetting material with pH responsiveness prepared according to the method.

[0037] After testing, the water contact angle of the pH-responsive multifunctional super-wetting material prepared by the present invention is higher than 150°, and it has excellent pH responsiveness. When the pH is below the threshold, it exhibits super-hydrophobicity and does not change with time. When the pH is above the threshold, the water contact angle can quickly become 0, and the response time is extremely short. It also has excellent mechanical stability. After strong external extrusion, the material quality is not obviously damaged, and the water absorption rate changes are also extremely low.

[0038] The invention also discloses the application of the multifunctional super-wetting material with pH responsiveness in removing pollutants in water bodies.

[0039] Experiments have shown that the pH-responsive multifunctional super-wetting material disclosed in the present invention has excellent separation effects on a variety of oil-water mixtures, including dichloromethane / water, toluene / water, n-hexane / water, n-hexadecane / water, xylene / water, petroleum ether / water, etc., with separation efficiencies exceeding 95.5%.

[0040] Experiments have shown that the multifunctional super-wetting material with pH responsiveness disclosed in the present invention can be used to remove organic dyes, such as methylene blue, from water bodies.

[0041] Experiments have shown that the pH-responsive multifunctional super-wetting material disclosed in the present invention can also be used to adsorb heavy metal ions in water, including but not limited to one or more of copper ions, cadmium ions, iron ions, cobalt ions, and lead ions.

[0042] It has been found through experiments that when the heavy metal ions are selected from cobalt ions and / or lead ions, preferably, the preparation of the multifunctional super-wetting material with pH responsiveness includes:

[0043] (1) Tetraethyl orthosilicate and a mercaptosilane coupling agent are added simultaneously to an ethanol solution containing aqueous ammonia, and the reaction is completed at room temperature to obtain mercapto-modified silica particles;

[0044] (2) mixing the thiol-modified silica particles prepared in step (1), unsaturated fatty acids, a photoinitiator, and solvent A, and subjecting the mixture to a thiol-ene click reaction initiated by ultraviolet light to prepare pH-responsive silica particles;

[0045] (3) dispersing the pH-responsive silica particles prepared in step (2) in a solution of an alkaline substance, and preparing an alkali-treated intermediate product after a neutralization reaction;

[0046] The alkaline substance is selected from inorganic bases and / or organic bases;

[0047] (4) The alkali-treated intermediate product prepared in step (3), the adhesive and the solvent B are mixed and coated on the surface and interior of the substrate to obtain the multifunctional super-wetting material with pH responsiveness.

[0048] A neutralization reaction step is added to the preparation step, that is, the prepared pH-responsive silica particles are dispersed in a solution of an alkaline substance to prepare an alkali-treated intermediate product, and then a coating process is performed.

[0049] When the alkaline substance is selected from an inorganic base, water can be used as the solvent; when the alkaline substance is selected from an organic base, an organic solvent such as ethanol can be used as the solvent.

[0050] Preferably, the inorganic base is selected from sodium hydroxide, potassium hydroxide, ammonia water, etc.; the organic base is selected from triethylamine.

[0051] Experiments have found that after this alkaline treatment, especially when the alkaline substance is selected from sodium hydroxide, the adsorption performance of the pH-responsive multifunctional super-wetting material for cobalt ions and lead ions is significantly improved, especially for lead ions, with an ultra-high adsorption capacity of more than 180 mg / g.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] This invention utilizes a highly efficient and mild thiol-ene click reaction to graft naturally unsaturated fatty acids onto the surface of silica particles. The resulting hierarchical silica particles easily meet the surface roughness requirements for specific wettability and can be conveniently applied to a variety of substrates. The reversible protonation and deprotonation of carboxyl groups under different conditions imparts rapid pH-induced changes in surface wettability to the modified material.

[0054] The pH-responsive multifunctional superwetting material prepared by the present invention is superhydrophobic / superoleophilic under neutral / acidic conditions, and superhydrophilic / underwater superoleophobic under alkaline conditions. This unique property enables efficient separation of complex oil-water mixtures. Furthermore, thanks to the unique multi-level hierarchical structure and abundant polar groups on the particle surface, the modified superwetting material exhibits excellent mechanical stability and outstanding adsorption and removal capabilities for other pollutants in water, including organic dyes and heavy metal ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1TEM image of pH-responsive silica particles prepared in step (2) of Example 1;

[0056] Figure 2 The SEM image of the pH-responsive super-wettable modified sponge finally prepared in Example 1 (upper image) and the SEM image of the unmodified original sponge (lower image);

[0057] Figure 3 Curves showing the change of contact angle of water droplets with different pH values ​​on the surface of the pH-responsive super-wetting modified sponge prepared in Example 1 over time;

[0058] Figure 4 This is the mechanical stability curve of the pH-responsive super-wetting modified sponge prepared in Example 1;

[0059] Figure 5 TEM image of pH-responsive silica particles prepared in step (2) of Comparative Example 1;

[0060] Figure 6 TEM image of pH-responsive silica particles prepared in step (2) of Comparative Example 2;

[0061] Figure 7 These are digital photos of the pH-responsive super-wettable modified sponge prepared in Example 1 before and after treatment with a methylene blue aqueous solution;

[0062] Figure 8 The separation efficiency of the pH-responsive super-wettable modified sponge prepared in Example 1 for different oil-water mixtures;

[0063] Figure 9 The adsorption capacity of the pH-responsive super-wettable modified sponge prepared in Example 1 for different heavy metal ions. DETAILED DESCRIPTION

[0064] The present invention will be further described in detail below with reference to examples and comparative examples, but the embodiments of the present invention are not limited thereto.

[0065] Example 1

[0066] (1) Tetraethyl orthosilicate and mercaptopropyl trimethoxysilane (the molar ratio of tetraethyl orthosilicate to mercaptopropyl trimethoxysilane is 6:1, and the total volume of the two is 8 mL) are added dropwise to a stirred mixed solution of 100 g ethanol and 10 g ammonia water at room temperature at a rate of 30 mL / h. The mixed solution is stirred at room temperature for 20 h, and the solid product is collected by centrifugation and repeatedly washed with ethanol and deionized water. Finally, after drying, mercapto-modified silica particles are obtained, which are designated as SiO2-SH.

[0067] (2) 5 g of the thiol-modified silica particles prepared in step (1), 3 g of oleic acid, and 0.1 g of the photoinitiator benzoin dimethyl ether were ultrasonically dispersed in 50 g of ethanol. The mixed solution was irradiated with a 365 nm UV lamp (12 W) for 1 h, and the particles were collected by centrifugation and repeatedly washed with ethanol and deionized water. Finally, after drying, pH-responsive silica particles were obtained, which were designated as SiO2-COOH.

[0068] (3) 1 g of the pH-responsive silica particles prepared in step (2) and 1 g of the organic silicone adhesive were dispersed in 20 g of ethyl acetate to prepare a coating solution. A melamine sponge was then immersed in the coating solution for 30 min. The sponge was repeatedly squeezed to ensure that the sponge was filled with the solution. Finally, the sponge was cured at 120°C for 15 min to obtain a pH-responsive super-wetting modified sponge.

[0069] Figure 1 This is a TEM image of the pH-responsive silica particles prepared in step (2) of this example. The image shows that the silica particles have a multi-level hierarchical structure. Specifically, small spheres formed by the hydrolysis and condensation of the mercaptosilane coupling agent are attached to the surface of a "core" large sphere formed by the preferential hydrolysis and condensation of tetraethyl orthosilicate. The small spheres are roughly a few nanometers in size, and the large spheres are approximately 200 nanometers in diameter. The combination of the two not only increases the specific surface area of ​​the particles but also provides a micro / nano composite structure that is crucial for achieving superhydrophobicity.

[0070] Figure 2 This is a SEM image of the pH-responsive superwettable modified sponge prepared in this example. The image reveals that the unmodified sponge's three-dimensional network skeleton is smooth and flat, while the modified sponge's skeleton is evenly covered with silica particles. Because the particles encapsulate the sponge skeleton, the surface chemical properties of the particles determine the surface chemical properties of the sponge.

[0071] Figure 3Figure (a) shows the change curve of the contact angle of the pH-responsive super-wetting modified sponge surface prepared in this embodiment with water droplets of different pH values ​​over time. By observing the curves, it can be found that for acidic and neutral droplets, the modified sponge surface always exhibits super-hydrophobicity and does not change with time. When the pH is above the threshold, the modified sponge surface is converted to (super) hydrophilicity, and the hydrophilic conversion speed accelerates with the increase of the pH of the droplet. For droplets with pH = 13 (Figure (b)), the water contact angle of the sponge becomes 0 after 250 seconds. This conversion time is much shorter than that reported in other literatures and is attributed to the multi-level hierarchical structure and rich carboxyl content of the particle surface. This once again proves that the click chemistry method used in this study has a higher modification efficiency than the traditional silane coupling agent surface modification of silica, and is a very promising method for preparing particles with special group surface modification.

[0072] The water contact angle of the pH-responsive superwettable modified sponge prepared in this example is 155.5°.

[0073] The mechanical stability of the pH-responsive super-wetting modified sponge prepared in this example was tested by mechanical extrusion. Specifically, strong external mechanical extrusion was used to achieve complete deformation of the sample. After every 5 cycles, the mass loss and water absorption rate of the modified sponge were recorded. The test results are shown in Figure 2. Figure 4 As shown in the figure, it can be seen that after 100 cycles of strong external compression, the water absorption rate of the modified sponge remains below 0.15g / g. At the same time, there is no obvious loss in the mass of the modified sponge, which shows that the particles can be firmly adhered to the substrate and have not fallen off due to external forces.

[0074] Comparative Example 1

[0075] (1) At room temperature, 6 mL of tetraethyl orthosilicate was added dropwise to a stirred mixture of 100 g of ethanol and 10 g of ammonia water. After the mixture was stirred at room temperature for 2 hours, 2 mL of mercaptopropyltrimethoxysilane was added dropwise thereto. The addition rate was 30 mL / h. The mixture was stirred at room temperature for 18 hours, and then the solid product was collected by centrifugation and repeatedly washed with ethanol and deionized water. Finally, the thiol-modified silica particles were obtained after drying.

[0076] Steps (2) to (3) are exactly the same as those in Example 1.

[0077] Figure 5 This is a TEM image of the pH-responsive silica particles prepared in step (2) of this comparative example. Observation of the image reveals that the edges of the particle surfaces are very smooth, with no small balls attached, and the multi-level hierarchical structure disappears.

[0078] The water contact angle of the pH-responsive superwettable modified sponge prepared in this comparative example is 132.7°.

[0079] Comparative Example 2

[0080] (1) To a stirred mixture of 100 g of ethanol and 10 g of aqueous ammonia at room temperature, 8 mL of mercaptopropyltrimethoxysilane was added dropwise at a rate of 30 mL / h. The mixture was stirred at room temperature for 20 h, and the solid product was collected by centrifugation and repeatedly washed with ethanol and deionized water. Finally, the solid product was dried to obtain mercapto-modified silica particles.

[0081] Steps (2) to (3) are exactly the same as those in Example 1.

[0082] Figure 6 This is a TEM image of the pH-responsive silica particles prepared in step (2) of this comparative example. From this image, it can be found that due to the low functionality of the mercaptosilane coupling agent, it does not have the ability to form spherical particles when added alone.

[0083] The water contact angle of the pH-responsive super-wettable modified sponge prepared in this comparative example is 130°.

[0084] Example 2

[0085] (1) Tetraethyl orthosilicate and mercaptopropyl trimethoxysilane (the molar ratio of tetraethyl orthosilicate to mercaptopropyl trimethoxysilane is 6:1, and the total volume of the two is 8 mL) are added dropwise simultaneously to a stirred mixed solution of 100 g of ethanol and 10 g of ammonia water at room temperature at a rate of 30 mL / h. The mixed solution is stirred at room temperature for 20 h, and the solid product is collected by centrifugation and repeatedly washed with ethanol and deionized water. Finally, the thiol-modified silica particles are obtained after drying.

[0086] (2) 5 g of the thiol-modified silica particles prepared in step (1), 3 g of oleic acid, and 0.1 g of the photoinitiator benzoin dimethyl ether were ultrasonically dispersed in 50 g of ethanol. The mixed solution was irradiated with a 365 nm UV lamp (12 W) for 1 h, and the particles were collected by centrifugation and repeatedly washed with ethanol and deionized water. Finally, the pH-responsive silica particles were obtained after drying.

[0087] (3) The pH-responsive silica particles prepared in step (2) were dispersed in a NaOH aqueous solution with a pH of 14, and then immersed for 6 hours, centrifuged, washed, and dried to obtain an alkali-treated intermediate product, which was recorded as SiO2-COONa.

[0088] (4) 1 g of the alkali-treated intermediate product prepared in step (3) and 1 g of the organic silicone adhesive were dispersed in 20 g of ethyl acetate to prepare a coating solution. A melamine sponge was then immersed in the coating solution for 30 min. The sponge was repeatedly squeezed to ensure that the interior was filled with the solution. Finally, after curing at 120° C. for 15 min, a pH-responsive super-wetting modified sponge was obtained.

[0089] Example 3

[0090] The preparation process is basically the same as that of Example 2, except that the NaOH aqueous solution in step (3) is replaced by a 25 wt% ammonia aqueous solution, and the alkali-treated intermediate product prepared in step (3) is recorded as SiO2-COONH4.

[0091] Example 4

[0092] The preparation process is basically the same as that of Example 2, except that the NaOH aqueous solution in step (3) is replaced by a 50 wt% triethylamine ethanol solution, and the alkali-treated intermediate product prepared in step (3) is recorded as SiO2-COOC6H 16 N.

[0093] Example 5

[0094] (1) At room temperature, 12 mL of a mixture of silane coupling agents was added dropwise to a stirred mixture of 120 g of ethanol and 9.6 g of ammonia water. The molar ratio of tetraethyl orthosilicate to 3-mercaptopropyltriethoxysilane was 4:1, and the addition rate was 45 mL / h. The mixed solution was stirred at room temperature for 24 h, and the solid product was collected by centrifugation and repeatedly washed with ethanol and deionized water. Finally, the thiol-modified silica particles were obtained after drying.

[0095] (2) 6 g of the thiol-modified silica particles prepared in step (1), 10 g of ricinoleic acid, and 0.15 g of the photoinitiator benzoin dimethyl ether were ultrasonically dispersed in 75 g of ethanol. The mixed solution was irradiated with a 365 nm UV lamp (12 W) for 2 h, and the particles were collected by centrifugation and repeatedly washed with ethanol and deionized water. Finally, the pH-responsive silica particles were obtained after drying.

[0096] (3) 1 g of the pH-responsive silica particles prepared in step (2) and 0.5 g of epoxy resin adhesive were dispersed in 15 g of acetone to prepare a coating solution. The cotton fabric was then immersed in the coating solution for 30 min. Finally, the fabric was cured at 60°C for 6 h to obtain a pH-responsive superwettable fabric.

[0097] TEM characterization shows that the pH-responsive silica particles prepared in step (2) of this example also have a multi-level hierarchical structure.

[0098] The water contact angle of the pH-responsive super-wettable modified fabric prepared in this example is 159.6°.

[0099] The modified fabric prepared in this example has super-hydrophobicity for acidic and neutral droplets, and becomes (super) hydrophilic for alkaline droplets. For droplets with a pH of 14, the water contact angle of the fabric surface becomes 0 after about 10 minutes.

[0100] Example 6

[0101] (1) At room temperature, 5 mL of a mixture of silane coupling agents was added dropwise to a stirred mixture of 50 g of ethanol and 7.5 g of ammonia water. The molar ratio of tetraethyl orthosilicate to mercaptopropylmethyldimethoxysilane was 1:1, and the addition rate was 50 mL / h. The mixed solution was stirred at room temperature for 24 h, and the solid product was collected by centrifugation and repeatedly washed with ethanol and deionized water. Finally, the thiol-modified silica particles were obtained after drying.

[0102] (2) 10 g of the thiol-modified silica particles prepared in step (1), 10 g of linolenic acid, and 0.2 g of the photoinitiator 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide were ultrasonically dispersed in 125 g of ethanol. The mixed solution was irradiated with a 365 nm UV lamp (12 W) for 2 h, and the particles were collected by centrifugation and repeatedly washed with ethanol and deionized water. Finally, the pH-responsive silica particles were obtained after drying.

[0103] (3) 1 g of the pH-responsive silica particles prepared in step (2) and 2 g of the aqueous polyurethane adhesive were dispersed in 5 g of water to prepare a coating solution. A melamine sponge was then immersed in the coating solution for 30 min. The sponge was repeatedly squeezed to ensure that the sponge was filled with the solution. Finally, the pH-responsive super-wetting modified sponge was obtained after curing at 80°C for 24 h.

[0104] TEM characterization shows that the pH-responsive silica particles prepared in step (2) of this example also have a multi-level hierarchical structure.

[0105] The water contact angle of the pH-responsive superwettable modified sponge prepared in this example is 158.3°.

[0106] The modified sponge prepared in this example is super-hydrophobic to acidic and neutral droplets, and its surface becomes (super) hydrophilic to alkaline droplets. For a droplet with a pH of 14, the water contact angle of the sponge surface becomes 0 after about 3 minutes.

[0107] Example 7

[0108] (1) At room temperature, 12 mL of a mixture of silane coupling agents was added dropwise to a stirred mixture of 80 g of ethanol and 12 g of ammonia water. The molar ratio of tetraethyl orthosilicate to 3-mercaptopropyltriethoxysilane was 1:1, and the addition rate was 20 mL / h. The mixed solution was stirred at room temperature for 36 h, and then silica particles were collected by centrifugation and repeatedly washed with ethanol and deionized water. Finally, the thiol-modified silica particles were obtained after drying.

[0109] (2) 10 g of the thiol-modified silica particles prepared in step (1), 15 g of linoleic acid, and 0.1 g of the photoinitiator benzoin dimethyl ether were ultrasonically dispersed in 100 g of ethanol. The mixed solution was irradiated with a 365 nm UV lamp (12 W) for 4 h, and the particles were collected by centrifugation and repeatedly washed with ethanol and deionized water. Finally, the pH-responsive silica particles were obtained after drying.

[0110] (3) 1 g of the pH-responsive silica particles prepared in step (2) and 2 g of the organic silicone adhesive were dispersed in 20 g of ethyl acetate to prepare a coating solution. The copper foam was then immersed in the coating solution for 30 minutes. Finally, after curing at 120° C. for 30 minutes, a pH-responsive super-wetting modified copper foam was obtained.

[0111] TEM characterization shows that the pH-responsive silica particles prepared in step (2) of this example also have a multi-level hierarchical structure.

[0112] The water contact angle of the pH-responsive super-wettable modified copper foam prepared in this example is 152.6°.

[0113] The modified copper foam prepared in this example is super-hydrophobic to acidic and neutral droplets, and its surface becomes (super) hydrophilic to alkaline droplets. For a droplet with a pH of 14, the water contact angle on the copper foam surface becomes 0 after about 5 minutes.

[0114] Application Examples

[0115] (1) Organic pollutant treatment effect test

[0116] Add a powder (pH-responsive silica particles prepared in step (2) of Example 1) to a final concentration of 1 g / L to a 100 mg / L aqueous solution of the organic dye methylene blue. After magnetic stirring at room temperature for 24 hours, filter the solution with filter paper and measure the residual concentration. If necessary, dilute the sample to meet the detector's requirements.

[0117] Figure 7These are digital photos of the pH-responsive silica particles prepared in Example 1 before (right bottle) and after (left bottle) treatment with a methylene blue aqueous solution. Comparison shows that the adsorbed solution is clear and transparent, with no obvious dye residue.

[0118] (2) Separation effect test of different oil-water mixtures

[0119] The pH-responsive super-wettable modified sponge prepared in Example 1 was immersed in an oil-water mixture consisting of two liquids (one is water and the other is an organic solvent) of equal mass for 10 minutes, and the remaining mass of the organic solvent was weighed.

[0120] Figure 8 The separation efficiency of the pH-responsive super-wettable modified sponge prepared in Example 1 for different oil-water mixtures showed that the separation efficiency was higher than 95.5%.

[0121] (3) Adsorption capacity test of different heavy metal ions

[0122] Add powder (silica particles grafted with various groups) to a final concentration of 1 g / L to a 100 mg / L aqueous solution of metal ions. After magnetic stirring at room temperature for 24 hours, filter through filter paper and measure the residual concentration. If necessary, dilute the sample to meet the detector's requirements.

[0123] Figure 9 The SiO2-SH prepared in step (1) of Example 1, the SiO2-COOH prepared in step (2), and the alkali-treated intermediates SiO2-COONa, SiO2-COONH4 and SiO2-COOC6H prepared in steps (3) of Examples 2 to 4, respectively, are 16 The adsorption capacity of SiO2-SH, SiO2-COOH and particles treated with different alkalis for five common heavy metal ions was tested. 2+ and Cd 2+ , the adsorption capacity of the five particles is not much different; for Fe 3+ , the adsorption capacity of SiO2-COONa is poor; for Co 2+ and Pb 2+ The adsorption capacity of SiO2-COONa was significantly improved, especially for Pb 2+ It has an ultra-high adsorption capacity of over 180mg / g.

[0124] The applicant declares that the present invention illustrates the detailed method of the present invention through the above embodiments, but the present invention is not limited to the above detailed method.

Claims

1. A method for preparing a multifunctional super-wetting material with pH responsiveness, characterized in that: The steps include: (1) Tetraethyl orthosilicate and a mercaptosilane coupling agent are added simultaneously to an ethanol solution containing aqueous ammonia, and the reaction is completed at room temperature to obtain mercapto-modified silica particles; (2) mixing the thiol-modified silica particles prepared in step (1), unsaturated fatty acids, a photoinitiator, and solvent A, and subjecting the mixture to a thiol-ene click reaction initiated by ultraviolet light to prepare pH-responsive silica particles; (3) The pH-responsive silica particles prepared in step (2), an adhesive, and a solvent B are mixed and coated on the surface and interior of the substrate to obtain the pH-responsive multifunctional super-wetting material.

2. The method for preparing a multifunctional super-wetting material with pH responsiveness according to claim 1, characterized in that: In step (1): The mercaptosilane coupling agent is selected from one or more of mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, mercaptopropylmethyldimethoxysilane, and 3-mercaptopropyltributoxysilane; The molar ratio of tetraethyl orthosilicate to mercaptosilane coupling agent is 1 to 10:1; In the ethanol solution, the total concentration of tetraethyl orthosilicate and mercaptosilane coupling agent is 0.04-0.15 mL / g, and the mass concentration of ammonia water is 0.05-0.2 g / g.

3. The method for preparing a multifunctional super-wetting material with pH responsiveness according to claim 1, characterized in that: In step (2): The unsaturated fatty acid is selected from one or more of linoleic acid, oleic acid, erucic acid, linolenic acid, arachidonic acid, nervonic acid, 10-hydroxy-2-decenoic acid, myristic acid, palmitoleic acid, ricinoleic acid, eicosapentaenoic acid, and docosahexaenoic acid; The photoinitiator is selected from one or more of 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphosphonate, 2-methyl-1-[4-methylthiophenyl]-2-morpholinyl-1-propanone, 2-isopropylthioxanthone, ethyl 4-dimethylaminobenzoate, benzoin dimethyl ether, methyl o-benzoylbenzoate, 4-phenylbenzophenone, and 4-chlorobenzophenone; The solvent A is selected from one or more of ethanol, tetrahydrofuran, ether, dichloromethane, chloroform and methanol.

4. The method for preparing a multifunctional super-wetting material with pH responsiveness according to claim 1, characterized in that: In step (2): The mass ratio of thiol-modified silica particles to unsaturated fatty acids is 1:0.5-2.0; The mass concentration of the thiol-modified silica particles in the solvent is 0.03-0.2 g / g.

5. The method for preparing a multifunctional super-wetting material with pH responsiveness according to claim 1, characterized in that: In step (3): The adhesive is selected from one or more of urea-formaldehyde resin, polyvinyl acetate resin, polyacrylic acid resin, polyurethane, epoxy resin, and silicone; The mass ratio of pH-responsive silica particles to adhesive is 1:0.3 to 5.0; Solvent B is selected from one or more of ethyl acetate, acetone, and water; The mass concentration of pH-responsive silica particles in solvent B is 0.01 to 0.5 g / g; The coating includes spray coating or dipping coating; The substrate has a porous structure and is selected from fabric, sponge, foam copper or aerogel.

6. The method for preparing a multifunctional super-wetting material with pH responsiveness according to any one of claims 1 to 5, characterized in that: In step (1): The molar ratio of tetraethyl orthosilicate to mercaptosilane coupling agent is 1 to 6:1; In the ethanol solution, the total concentration of tetraethyl orthosilicate and mercaptosilane coupling agent is 0.08-0.15 mL / g, and the mass concentration of ammonia water is 0.08-0.15 g / g; In step (2): The mass ratio of thiol-modified silica particles to unsaturated fatty acids is 1:0.6-1.7; The mass concentration of the thiol-modified silica particles in the solvent is 0.08 to 0.1 g / g; In step (3): The mass ratio of pH-responsive silica particles to adhesive is 1:0.5-2.0; The mass concentration of the pH-responsive silica particles in solvent B is 0.05 to 0.2 g / g.

7. A multifunctional super-wettable material with pH responsiveness prepared according to the method according to any one of claims 1 to 6.

8. Use of the multifunctional super-wetting material with pH responsiveness according to claim 7 in removing pollutants from water, characterized in that: The pollutants are selected from one or more of oil, heavy metal ions, and organic dyes.

9. The use of the multifunctional super-wetting material with pH responsiveness according to claim 8 in removing pollutants from water, characterized in that: The pollutants are selected from heavy metal ions; The preparation of the multifunctional super-wetting material with pH responsiveness comprises: (1) Tetraethyl orthosilicate and a mercaptosilane coupling agent are added simultaneously to an ethanol solution containing aqueous ammonia, and the reaction is completed at room temperature to obtain mercapto-modified silica particles; (2) mixing the thiol-modified silica particles prepared in step (1), unsaturated fatty acids, a photoinitiator, and solvent A, and subjecting the mixture to a thiol-ene click reaction initiated by ultraviolet light to prepare pH-responsive silica particles; (3) dispersing the pH-responsive silica particles prepared in step (2) in a solution of an alkaline substance, and preparing an alkali-treated intermediate product after a neutralization reaction; The alkaline substance is selected from inorganic bases and / or organic bases; (4) The alkali-treated intermediate product prepared in step (3), the adhesive and the solvent B are mixed and coated on the surface and interior of the substrate to obtain the multifunctional super-wetting material with pH responsiveness.

10. The use of the multifunctional super-wetting material with pH responsiveness according to claim 9 in removing pollutants from water, characterized in that: The heavy metal ions are selected from one or more of copper ions, cadmium ions, iron ions, cobalt ions, and lead ions.

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