A super hydrophilic-high oleophobic coating, coating, preparation method, material and application thereof

Abstract

The present invention discloses a super-hydrophilic high oleophobic coating, coating and preparation method thereof, material and application, the super-hydrophilic high oleophobic coating includes an ionic fluorocarbon surfactant, an organic nanosphere and water, the surface of the organic nanosphere is modified with a charged group, and the charge of at least one charged group is opposite to the charge of the ionic fluorocarbon surfactant. The above-mentioned super-hydrophilic high oleophobic coating is applied to the surface of the substrate, and after drying, a super-hydrophilic high oleophobic coating can be formed on the surface of the substrate. The raw material cost of the above-mentioned coating is low and environmentally friendly, and the method for preparing the coating is simple, easy to control, and suitable for industrial production; more importantly, the coating prepared by the above-mentioned coating has super-hydrophilic, high oleophobic performance, has good application prospects in oil-water separation, anti-oil pollution, etc., and the prepared coating has good flexibility, is more firmly combined with the substrate, and can effectively improve the stability and wear resistance of the coating.

Description

Technical Field

[0001] The present invention relates to the technical field of oil-water separation material preparation, and in particular to a super-hydrophilic-highly oleophobic coating, a coating, a preparation method thereof, a material, and applications thereof. Background Art

[0002] Oil-water pollution is one of the most significant water pollution problems currently faced, posing a serious threat to human health and the ecological environment. Superhydrophilic-highly oleophobic materials have a lower water contact angle than oil, repelling oil while also being able to remove it under the action of water. This offers advantages in oil-water separation over superhydrophobic-superoleophilic and superhydrophilic-underwater superoleophobic oil-water separation materials. More importantly, once oil stains adhere to the surface of superhydrophilic-highly oleophobic materials, they can spontaneously remove the oil in water, thus avoiding the problem of oil adhesion during use. This demonstrates unique advantages in addressing membrane fouling and efficiently separating and emulsifying oily wastewater.

[0003] At present, the preparation of superhydrophilic-high oleophobic materials is mainly achieved through chemical grafting and surface coating of superhydrophilic-high oleophobic coatings. Since the former is only applicable to substrates with specific reactive groups on the surface, it does not have universal substrate applicability, which limits its development in the field of oil-water separation. The latter is simple to operate and easy to implement, and is widely used for superhydrophilic-high oleophobic modification of materials. However, when superhydrophilic-high oleophobic materials are prepared by the coating method, the coating usually contains oily organic solvents, which harm the ecological environment and human health. In order to improve the superhydrophilicity and oleophobicity of the coating, it is generally necessary to add inorganic nanoparticles such as SiO2, TiO2, etc. to the coating to construct a multi-scale rough structure on the surface of the substrate. However, such nanoparticles are relatively expensive and have high rigidity, which affects the softness of the coating material and is not conducive to the operation and recycling of oil-water separation materials. In addition, due to the lack of chemical bond connection between the substrate surface and the superhydrophilic-high oleophobic coating, the coating is easily lost during use, resulting in a decrease in the oil-water separation performance and service life of the material, which is not conducive to practical application.

[0004] Therefore, at this stage, there is an urgent need for a coating with low raw material cost, environmental protection, and the ability to prepare a super-hydrophilic-high oleophobic coating with good flexibility and strong bonding to the substrate, so as to improve the material's oil-water separation performance, oil-proof ability and service life. Summary of the Invention

[0005] To solve the above problems, the present invention provides a super hydrophilic-high oleophobic coating, a coating and its preparation method, material and application. The present invention forms a super hydrophilic-high oleophobic coating in water through electrostatic action between a charged ionic fluorocarbon surfactant and organic nanospheres with opposite charges on the surface. The coating is coated on the surface of a substrate and dried to prepare a coating that not only has super hydrophilic-high oleophobic properties, but also has good flexibility and better adhesion to the substrate, which is beneficial to improving the bonding strength between the coating and the substrate during use, thereby improving the performance of the material containing the coating in oil-water separation, oil pollution prevention and its service life.

[0006] Specifically, the following technical solutions are provided:

[0007] The first aspect of the present invention provides a superhydrophilic-high oleophobic coating, which comprises the following components: an ionic fluorocarbon surfactant, organic nanospheres and water; the surface of the organic nanospheres is modified with charged groups, and the charge of at least one charged group is opposite to the charge of the ionic fluorocarbon surfactant.

[0008] Furthermore, the mass ratio of the ionic fluorocarbon surfactant to the organic nanospheres in the super-hydrophilic-high oleophobic coating is preferably (0.5-10):1, such as 0.1:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, and the like, including but not limited to the mass ratios listed above. Although treatment with an ionic fluorocarbon surfactant can improve the hydrophilicity of the material surface to a certain extent, it cannot achieve the super-hydrophilic-high oleophobic effect. The synergistic effect of the dense and rough structure of the coating is required to impart the super-hydrophilic-high oleophobic properties to the coating. To obtain a dense coating with a rough micro-nanostructure, the mass ratio of the ionic fluorocarbon surfactant to the organic nanospheres in the coating is preferably controlled within the range of (0.5-10):1 to form a super-hydrophilic-high oleophobic coating.

[0009] Furthermore, the super hydrophilic-high oleophobic coating is obtained by dispersing an ionic fluorocarbon surfactant and organic nanospheres in water; preferably, the solid content of the super hydrophilic-high oleophobic coating is 0.2%-50%, for example, 0.2%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc., including but not limited to the solid content values listed above, and the above solid content is the mass percentage of the ionic fluorocarbon surfactant and the organic nanospheres in the super hydrophilic-high oleophobic coating.

[0010] Furthermore, the ionic fluorocarbon surfactant is preferably a water-soluble anionic fluorocarbon surfactant, a water-soluble cationic fluorocarbon surfactant or a water-soluble amphoteric fluorocarbon surfactant.

[0011] Preferably, the water-soluble anionic fluorocarbon surfactant is selected from one or more of carboxylate anionic fluorocarbon surfactants, sulfonate anionic fluorocarbon surfactants, sulfate anionic fluorocarbon surfactants and phosphate anionic fluorocarbon surfactants.

[0012] Preferably, the water-soluble cationic fluorocarbon surfactant is a perfluoroalkylamine oxide fluorocarbon surfactant and / or a quaternary ammonium salt fluorocarbon surfactant.

[0013] Preferably, the water-soluble amphoteric fluorocarbon surfactant is selected from one or more of a betaine-type zwitterionic fluorocarbon surfactant, an imidazoline-type amphoteric fluorocarbon surfactant, an amine oxide-type amphoteric fluorocarbon surfactant, and a phosphate-type amphoteric fluorocarbon surfactant.

[0014] Furthermore, the particle size of the organic nanospheres is preferably 5 nm-800 nm, for example, 5 nm, 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, etc., including but not limited to the particle sizes listed above.

[0015] Furthermore, the organic nanospheres can be selected from one or more of polystyrene nanospheres, polymethyl methacrylate nanospheres, polydopamine nanospheres, polyvinylidene fluoride nanospheres, polycaprolactone nanospheres, polyethylene glycol nanospheres, chitosan nanospheres, and sodium alginate nanospheres; preferably, the organic nanospheres include at least one thermoplastic organic nanosphere.

[0016] Furthermore, the charged group is selected from one or more of sulfonic acid group, carboxylic acid group, amino group, quaternary ammonium salt, sulfate group, and phosphoric acid group; preferably, the charged group is modified on the surface of the organic nanosphere through chemical bonds.

[0017] The second aspect of the present invention provides a method for preparing a super hydrophilic-high oleophobic coating, wherein the super hydrophilic-high oleophobic coating described in the first aspect is coated on the surface of a substrate, and the super hydrophilic-high oleophobic coating is formed on the surface of the substrate after drying.

[0018] The present invention applies the coating comprising the ionic fluorocarbon surfactant and organic nanospheres with opposite surface charges to the surface of a substrate. In the presence of water, the coating self-assembles through electrostatic action to form an organic nanosphere-fluorocarbon surfactant complex. After drying, a coating having a micro-nano structure is formed on the surface of the substrate. The coating exhibits superhydrophilic and highly oleophobic properties. In addition, the coating formed by the organic nanospheres has good flexibility, which not only does not affect the flexibility of the material itself but also helps to improve the adhesion between the coating and the substrate, thereby helping to increase the service life of the material. In addition, the coating of the present invention has self-curing properties. By regulating the drying temperature, for example, regulating the drying temperature to near the glass transition temperature of the organic nanospheres (slightly higher than the glass transition temperature), the organic nanospheres will undergo micro-melting during the drying process. Without the need for additional additives, an integrated connection structure will be formed between adjacent organic nanospheres, thereby forming a coating with a more stable and compact structure. After the organic nanospheres are dried, the molten portion of the organic nanospheres can better fill the pores on the surface of the substrate, increasing the effective contact area, thereby forming a closer physical contact. Organic nanospheres with different glass transition temperatures can also be blended. During the drying process, the organic nanospheres heated to a low glass transition temperature will melt while the organic nanospheres heated to a high glass transition temperature will not melt, thereby encapsulating and adhering the nanospheres with a high melting temperature and firmly fixing them to the surface of the material. This can effectively improve the bonding strength between the coating and the substrate, which is conducive to further improving the durability of the coating.

[0019] Furthermore, the coating method includes but is not limited to spraying, dipping, etc.

[0020] Furthermore, the drying temperature is preferably 40-200°C.

[0021] Furthermore, when the organic nanospheres include at least one thermoplastic organic nanosphere, the glass transition temperature of the organic nanosphere with the lowest glass transition temperature among the thermoplastic organic nanospheres is Tg, the drying temperature is Tg + (5-20) ° C, and the drying time is 5-20 min. The drying temperature and time will affect the formation of the micro-nano structure of the coating and its bonding strength with the substrate. If the drying temperature is too low or the drying time is too short, a stable and compact coating cannot be formed through the effective melting of the organic nanospheres. If the drying temperature is too high or the drying time is too long, the organic nanospheres will melt excessively, forming a relatively flat coating on the surface of the substrate without rough micro-nano structures, which affects the hydrophilic and oleophobic effects of the coating. Therefore, in order to form a stable, compact coating with a rough micro-nano structure, it is preferred that the drying temperature is controlled within the range of Tg + (5-20) ° C and the drying time is controlled within the range of 5-20 min, so that the coating has both super-hydrophilic and high oleophobic properties and good durability.

[0022] Furthermore, when the organic nanospheres include thermoplastic first organic nanospheres and thermoplastic second organic nanospheres, and the glass transition temperature of the second organic nanospheres is greater than the glass transition temperature of the first organic nanospheres, preferably, the drying temperature is set between the glass transition temperature of the first organic nanospheres and the glass transition temperature of the second organic nanospheres, so that the second organic nanospheres are embedded and adhered to the surface of the material through the melting of the first organic nanospheres.

[0023] The third aspect of the present invention provides a super hydrophilic-high oleophobic coating prepared by the preparation method described in the second aspect.

[0024] A fourth aspect of the present invention provides a super hydrophilic-high oleophobic material, comprising a substrate and a coating disposed on the surface of the substrate, wherein the coating is the super hydrophilic-high oleophobic coating described in the third aspect.

[0025] The fifth aspect of the present invention provides an application of the super hydrophilic-high oleophobic material described in the fourth aspect in oil-water separation and / or oil-proof materials.

[0026] Furthermore, the super-hydrophilic-highly oleophobic material can achieve a separation efficiency of up to 99.9% for oil-water mixtures and up to 99.5% for water-oil emulsions.

[0027] Beneficial effects of the present invention:

[0028] The present invention provides a super-hydrophilic-highly oleophobic coating, which is composed of an ionic fluorocarbon surfactant, organic nanospheres and water. Compared with inorganic nanoparticles, the organic nanospheres used in the present invention are inexpensive, which helps reduce raw material costs. In addition, the coating uses water as the dispersion medium and does not require the introduction of organic solvents, making it more environmentally friendly.

[0029] The present invention provides a method for preparing a super-hydrophilic-high oleophobic coating, which is obtained by applying the above-mentioned coating on a substrate and drying it, and by electrostatically combining an ionic fluorocarbon surfactant with oppositely charged organic nanospheres, a one-step electrostatic self-assembly is performed without the need for complex chemical modification or multi-step reaction. A coating having super-hydrophilic-high oleophobic properties can be prepared; the above-mentioned preparation method is simple, efficient, and suitable for industrial preparation. In addition, the present invention can regulate the drying temperature so that the organic nanospheres undergo micro-melting during the drying process, thereby self-curing to form a coating with a compact structure, stable structure, and stronger bonding to the substrate without the need for additional additives, thereby effectively improving the stability and wear resistance of the coating.

[0030] The coating prepared by the above-mentioned coating and method exhibits excellent super-hydrophilic and highly oleophobic properties. Its contact angle with water in air is 0°, and complete water infiltration takes only 0.1 s. Its contact angle with oil droplets (hexadecane) is 153°. Furthermore, it exhibits low adhesion to oil droplets such as hexadecane, making the material containing the coating less susceptible to oil adhesion. Furthermore, the coating has good flexibility, which improves the adhesion between the coating and the substrate, and helps improve the hydrophilic and oleophobic properties of the material containing the coating under long-term use or stress. Therefore, the super-hydrophilic and highly oleophobic material containing the above-mentioned coating protected by the present invention has good application prospects in oil-water separation and oil pollution prevention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a scanning electron microscope (SEM) image of the modified fabric prepared in Example 1 of the present invention;

[0032] Figure 2 This is a test of the contact angle of the modified fabric prepared in Example 1 of the present invention to water;

[0033] Figure 3 This is the contact angle test of the modified fabric prepared in Example 1 of the present invention on oil (hexadecane);

[0034] Figure 4 is a SEM image of the modified fabric prepared in Example 10 of the present invention;

[0035] Figure 5 is a SEM image of the modified fabric prepared in Example 11 of the present invention. DETAILED DESCRIPTION

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. The terms "including" or "comprising" as used herein may also be replaced by the enclosed form "being" or "consisting of."

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0038] The preparation of the sulfonic acid group-modified polystyrene nanospheres and the quaternary ammonium salt-modified polystyrene nanospheres used in the following examples and comparative examples is as follows:

[0039] Polystyrene nanospheres: Dissolve 0.2 g of sodium dodecyl sulfate and 0.1 g of sodium carbonate in 300 mL of distilled water. The resulting solution is transferred to a three-necked flask and purged with nitrogen for 30 minutes. Subsequently, 30 mL of styrene is added with rapid stirring, and the solution is heated to 60°C. After 30 minutes, 15 mL of aqueous potassium persulfate solution is added, and the polymerization reaction is carried out at 75°C for 20 hours. After cooling to room temperature, the product is washed alternately with ethanol and water and dried at 60°C to obtain polystyrene nanoparticles.

[0040] Sulfonic acid-modified polystyrene nanospheres: 1 g of polystyrene nanospheres was ultrasonically dispersed in 40 mL of 98 wt% H₂SO₄. The sulfonation process was performed at 30°C for 48 hours. After cooling to room temperature, the mixture was poured into a large amount of water and thoroughly rinsed with water and ethanol. The mixture was then dried in a vacuum oven at 50°C overnight to obtain sulfonic acid-modified polystyrene nanospheres with a Tg of approximately 110°C.

[0041] Quaternary ammonium salt-modified polystyrene nanospheres (poly(styrene-butyl acrylate-p-vinylbenzyltrimethylammonium chloride)): 90 mL of distilled water was added to a 250 mL four-necked flask and nitrogen was introduced to remove air from the flask. The water bath temperature was maintained at 25°C and the stirring rate was maintained at 450 rpm / min. 5 mL of a 0.4 mol / L p-vinylbenzyltrimethylammonium chloride (VBT) solution was slowly added to the four-necked flask. After 15 minutes, a uniform mixture of 9.2 g of purified styrene (St) and 0.8 g of butyl acrylate (BA) was added to the flask. After a 2-hour reaction, the water bath temperature was set to 80°C and maintained for 5 minutes. Polymerization was initiated by adding 5 mL of a 20 g / L initiator (AIBA). The reaction was continued for 4-5 hours. After complete cooling, the mixture was vacuum filtered and dialyzed to remove unpolymerized monomers. Quaternary ammonium salt-modified polystyrene nanospheres were obtained with a Tg of approximately 105°C. Example 1

[0042] This embodiment relates to the preparation of a super hydrophilic-high oleophobic coating and a modified fabric, which specifically includes the following steps:

[0043] (1) Zwitterionic fluorocarbon surfactant FS-50 was added to water and ultrasonically dispersed in an ultrasonic machine for 30 min. Subsequently, sulfonic acid group-modified polystyrene nanospheres were added to the above solution and ultrasonically dispersed for 30 min to obtain a superhydrophilic-high oleophobic coating. The mass ratio of FS-50 to sulfonic acid group-modified polystyrene nanospheres was 2:1, and the solid content of the superhydrophilic-high oleophobic coating solution was 10%.

[0044] (2) The fabric was immersed in the superhydrophilic-high oleophobic coating for 20 min, and then the excess solution was removed and placed in an oven at 120 °C for 15 min to form a superhydrophilic-high oleophobic coating on the surface of the fabric to obtain a modified fabric.

[0045] The SEM image of the super hydrophilic-high oleophobic fabric prepared in this embodiment is as follows: Figure 1 As shown in FIG, a uniform and tightly bound nanoparticle modification layer can be observed on the surface of the fabric. In addition, the contact angles of the modified fabric prepared in this embodiment to water and oil in air were tested, and the results were as follows: Figure 2 、 3 As shown, it only takes 0.1 s for a water droplet to spread completely on the modified fabric surface ( Figure 2 ), showing excellent superhydrophilic properties, and the contact angle of oil droplets (hexadecane) on the modified fabric surface is 153° ( Figure 3 ), showing super oleophobic properties. It can be seen that the modified fabric prepared in this embodiment has super hydrophilic-high oleophobic properties. Example 2

[0046] This embodiment relates to the preparation of a super-hydrophilic-highly oleophobic coating and a modified fabric. The only difference from Example 1 is that the organic nanospheres in step (1) are polystyrene nanospheres modified with quaternary ammonium salts. The other conditions are the same, and the corresponding modified fabric is prepared.

[0047] The contact angles of the modified fabric prepared in this example to water and oil were tested. The results showed that the time for water to completely spread on the surface of the modified fabric was 0.1 s, and the contact angle of oil was 143°, showing super hydrophilic and high oleophobic properties. Example 3

[0048] This embodiment relates to the preparation of a super hydrophilic-high oleophobic coating and a modified fabric. The only difference from Example 1 is that the fluorocarbon surfactant in step (1) is a quaternary ammonium salt cationic fluorocarbon surfactant CF-700, and the other conditions are the same to prepare the corresponding modified fabric.

[0049] The contact angles of the modified fabric prepared in this example to water and oil were tested. The results showed that the time for water to completely spread on the fabric surface was 0.3 s, and the contact angle of oil was 136.5°, showing super hydrophilic and highly oleophobic properties. Example 4

[0050] This embodiment relates to the preparation of a super hydrophilic-high oleophobic coating and a modified fabric. The only difference from Example 2 is that the fluorocarbon surfactant in step (1) is a sulfate ester anionic fluorocarbon surfactant FS-60, and the other conditions are the same to prepare the corresponding modified fabric.

[0051] The contact angles of the modified fabric prepared in this example with respect to water and oil were tested. The results showed that the time for water to completely spread on the surface of the modified fabric was 0.1 s, and the contact angle of oil was 131.7°, exhibiting super hydrophilic and highly oleophobic properties. Example 5

[0052] This embodiment relates to the preparation of a super hydrophilic-high oleophobic coating and a modified fabric. The only difference from Example 2 is that the fluorocarbon surfactant in step (1) is a phosphate anionic fluorocarbon surfactant FS-61, and the other conditions are the same to prepare the corresponding modified fabric.

[0053] The contact angles of the modified fabric prepared in this example to water and oil were tested. The results showed that the water completely spread in 0.1 s and the contact angle to oil was 132°, showing super hydrophilic and highly oleophobic properties. Example 6

[0054] This embodiment relates to the preparation of a super-hydrophilic-highly oleophobic coating and a modified fabric. The only difference from Example 1 is that in step (1), the mass ratio of FS-50 to sulfonic acid group-modified polystyrene nanospheres is 0.5:1, and the other conditions are the same, and the corresponding modified fabric is prepared.

[0055] The contact angles of the modified fabric prepared in this example to water and oil were tested. The results showed that the time for water to completely spread on the surface of the modified fabric was 0.2 s, and the contact angle of oil was 132°, showing super hydrophilic and highly oleophobic properties. Example 7

[0056] This embodiment relates to the preparation of a super-hydrophilic-highly oleophobic coating and a modified fabric. The only difference from Example 1 is that in step (1), the mass ratio of FS-50 to sulfonic acid group-modified polystyrene nanospheres is 5:1, and the other conditions are the same, and the corresponding modified fabric is prepared.

[0057] The contact angles of the modified fabric prepared in this example to water and oil were tested. The results showed that the time for water to completely spread on the surface of the modified fabric was 0.1 s, and the contact angle of oil was 128.5°, showing super hydrophilic and high oleophobic properties. Example 8

[0058] This embodiment relates to the preparation of a super-hydrophilic-high oleophobic coating and a modified fabric. The only difference from Example 1 is that the solid content of the super-hydrophilic-high oleophobic coating solution in step (1) is 2%, and the other conditions are the same, and the corresponding modified fabric is prepared.

[0059] The contact angles of the modified fabric prepared in this example to water and oil were tested. The results showed that the time for water to completely spread on the surface of the modified fabric was 0.1 s, and the contact angle of oil was 127.6°, showing super hydrophilic and high oleophobic properties. Example 9

[0060] This embodiment relates to the preparation of a super-hydrophilic-high oleophobic coating and a modified fabric. The only difference from Example 1 is that the solid content of the super-hydrophilic-high oleophobic coating solution in step (1) is 30%, and the other conditions are the same, and the corresponding modified fabric is prepared.

[0061] The contact angles of the modified fabric prepared in this example to water and oil were tested. The results showed that the time for water to completely spread on the surface of the modified fabric was 0.1 s, and the contact angle of oil was 155.5°, showing super hydrophilic and high oleophobic properties. Example 10

[0062] This embodiment relates to the preparation of a super hydrophilic-high oleophobic coating and a modified fabric. The only difference from Example 1 is that the drying temperature in step (2) is 80°C, and the other conditions are the same, and the corresponding modified fabric is prepared.

[0063] The SEM image of the super hydrophilic-high oleophobic fabric prepared in this embodiment is as follows: Figure 4 As shown, a relatively dense layer of nanoparticles can be observed on the fabric surface, but significant pores are present. Furthermore, the contact angles of water and oil on the modified fabric prepared in this example were tested. The results showed that the time required for water to completely spread on the modified fabric surface was 0.1 s, and the contact angle for oil was 153.5°, demonstrating both superhydrophilic and highly oleophobic properties. Example 11

[0064] This embodiment relates to the preparation of a super hydrophilic-high oleophobic coating and a modified fabric. The only difference from Example 1 is that the drying temperature in step (2) is 140°C, and the other conditions are the same, and the corresponding modified fabric is prepared.

[0065] The SEM image of the super hydrophilic-high oleophobic fabric prepared in this embodiment is as follows: Figure 5 As shown, the modified layer on the fabric surface appears thin and has no obvious granular structure. Furthermore, the contact angles of water and oil on the modified fabric prepared in this example were tested. The results showed that the time it took for water to completely spread on the modified fabric surface was 0.2 s, and the contact angle for oil was 135°, demonstrating super-hydrophilic and highly oleophobic properties. Comparative Example 1

[0066] This comparative example relates to the preparation of a hydrophilic oleophobic coating and a modified fabric. The only difference from Example 1 is that the nanospheres in step (1) are hydrophilic silica nanospheres, and the other conditions are the same, and the corresponding modified fabric is prepared.

[0067] The contact angles of the modified fabric prepared in this comparative example to water and oil were tested. The results showed that the time for water to completely spread on the modified fabric was 0.1 s, and the contact angle of oil was 129.7°, showing hydrophilic and oleophobic properties. Comparative Example 2

[0068] This comparative example relates to the preparation of a hydrophilic and oleophobic coating and a modified fabric. The only difference from Example 1 is that in step (1), an equal amount of unmodified polystyrene nanospheres is used to replace the sulfonic acid group-modified polystyrene nanospheres. The other conditions are the same, and the corresponding modified fabric is prepared.

[0069] The contact angles of the modified fabric prepared in this comparative example to water and oil were tested. The results showed that the time for water to completely spread on the modified fabric was 0.5 s, and the contact angle of oil was 140.5°, showing hydrophilic and oleophobic properties. Comparative Example 3

[0070] This comparative example relates to the preparation of a hydrophilic and oleophobic coating and a modified fabric. The only difference from Example 1 is that the coating prepared in step (1) does not contain sulfonic acid group-modified polystyrene nanospheres, the solid content of the solution is 6.7%, and the other conditions are the same, and the corresponding modified fabric is prepared.

[0071] The contact angles of the modified fabric prepared in this comparative example to water and oil were tested. The results showed that the contact angle of water to oil was 105° after the complete spreading time of water was 0.1 s, showing super hydrophilic-oleophobic properties.

[0072] The contact angle test results of the modified fabrics prepared in the above examples and comparative examples to water and oil are shown in Table 1 below:

[0073] Table 1

[0074]

[0075] Performance Testing

[0076] The modified fabrics prepared in Example 1 and Example 10 were named modified fabrics 1 and 2, respectively. The modified fabrics 1 and 2 were used to perform separation efficiency, separation flux, and durability tests on an oil-water mixture. In addition, the fiber felts prepared in Example 1 and Example 10 were modified to obtain corresponding modified fiber felts 1 and 2, respectively. The modified fiber felts 1 and 2 were then used to perform separation efficiency, separation flux, and durability tests on an oil-in-water emulsion. The test process is as follows:

[0077] Preparation of oil-water mixture: 50 g of water and 50 g of hexadecane were mixed to prepare an oil-water mixture;

[0078] Test method for separation efficiency of oil-water mixture: weigh the weight of the separated oil on a balance, and use the formula Calculate the separation efficiency of the oil-water mixture, where E is the separation efficiency of the oil-water mixture, C1 is the mass of the oil after separation, and C0 is the mass of the oil before separation.

[0079] Preparation of oil-in-water emulsion: 1 g Tween 80, 500 g water and 10 g diesel were ultrasonically cleaned in an ultrasonic cleaner for 24 h to form a stable emulsion. The prepared emulsion remained stable for at least 48 h.

[0080] Test method for separation efficiency of oil-in-water emulsion: The test instrument is an infrared oil analyzer (Qingdao Juchuang Environmental Protection Group Co., Ltd.); 100 mL of the filtrate before and after filtration were taken, the treated extract was injected into a quartz cuvette, placed in the instrument sample cell, and the absorbance at 2930 cm⁻¹ was measured. The initial concentration of oil in the emulsion before treatment and the residual concentration of oil in the aqueous phase after filtration were measured as C0 and C1 (in ppm), respectively. Finally, according to , the separation efficiency is calculated.

[0081] Separation flux test method: the volume of permeate passing through unit membrane area per unit time, according to the formula Calculate the separation flux J, where V is the permeate volume in L and A is the effective membrane area in m 2 ; t is the running time, in hours.

[0082] Durability test method: Repeat the above separation operation for the above oil-water mixture, water-in-oil emulsion and oil-in-water emulsion 2 times and 10 times, and calculate the corresponding separation efficiency after 2 or 10 cycles respectively.

[0083] The above test results are shown in Table 2 below:

[0084] Table 2

[0085]

[0086] As shown in Table 2, the initial separation efficiency of modified fabric 2 prepared in Example 10 for the oil-water mixture is comparable to that of modified fabric 1 prepared in Example 1, but its separation flux for the oil-water mixture is significantly reduced. This is because the surface coating of the modified fabric prepared in Example 10 contains some holes, which cannot effectively separate the oil and water. The oil-water mixture enters the interior of the fabric through the holes, forming an oil film, which hinders the passage of water behind it, thereby affecting its separation flux for the oil-water mixture. In addition, the separation efficiency of modified fabric 1 for the oil-water mixture is not less than 99.9% after two cycles, and after 10 cycles, the separation efficiency of modified fabric 1 for the oil-water mixture is still as high as 97.5%. However, due to the detachment of the surface coating of modified fabric 2 after the cyclic separation operation, both oil and water pass through during the second separation, making it impossible to achieve oil-water separation.

[0087] In addition, the fiber felts were modified by the methods in Example 1 and Example 10 to obtain corresponding modified fiber felts 1 and 2, which had comparable initial separation efficiencies for water-in-oil emulsions, with modified fiber felt 1 having better initial separation efficiency for oil-in-water emulsions. More importantly, compared with modified fiber felt 2, modified fiber felt 1 had a significantly higher separation flux for oil-in-water emulsions and could still maintain a high separation efficiency after 10 cycles, demonstrating excellent durability.

[0088] The above embodiments are merely preferred embodiments for the purpose of fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

Claims

1. A method for preparing a super hydrophilic-high oleophobic coating, characterized in that: Applying a super-hydrophilic-high oleophobic coating on the surface of a substrate, and drying the coating to form the super-hydrophilic-high oleophobic coating on the surface of the substrate; The super-hydrophilic-highly oleophobic coating comprises the following components: an ionic fluorocarbon surfactant, organic nanospheres, and water; the surface of the organic nanospheres is modified with charged groups, and the charge of at least one charged group is opposite to that of the ionic fluorocarbon surfactant; The organic nanospheres include at least one type of thermoplastic organic nanospheres, and the glass transition temperature of the organic nanospheres with the lowest glass transition temperature among the thermoplastic organic nanospheres is Tg. The drying temperature is Tg + (5-20)°C.

2. The preparation method according to claim 1, characterized in that The mass ratio of the ionic fluorocarbon surfactant to the organic nanospheres in the super hydrophilic-high oleophobic coating is (0.5-10):

1.

3. The preparation method according to claim 1, characterized in that The super hydrophilic-high oleophobic coating is obtained by dispersing an ionic fluorocarbon surfactant and organic nanospheres in water; The solid content of the super hydrophilic-high oleophobic coating is 0.2%-50%.

4. The preparation method according to claim 1, characterized in that The ionic fluorocarbon surfactant is a water-soluble anionic fluorocarbon surfactant, a water-soluble cationic fluorocarbon surfactant or a water-soluble amphoteric fluorocarbon surfactant; The water-soluble anionic fluorocarbon surfactant is selected from one or more of carboxylate anionic fluorocarbon surfactants, sulfonate anionic fluorocarbon surfactants, sulfate anionic fluorocarbon surfactants and phosphate anionic fluorocarbon surfactants; The water-soluble cationic fluorocarbon surfactant is a perfluoroalkylamine oxide fluorocarbon surfactant and / or a quaternary ammonium salt fluorocarbon surfactant; The water-soluble amphoteric fluorocarbon surfactant is selected from one or more of a betaine-type zwitterionic fluorocarbon surfactant, an imidazoline-type amphoteric fluorocarbon surfactant, an amine oxide-type amphoteric fluorocarbon surfactant, and a phosphate-type amphoteric fluorocarbon surfactant.

5. The preparation method according to claim 1, characterized in that Contain at least one of the following characteristics: (1) The particle size of the organic nanospheres is 5 nm to 800 nm; (2) The organic nanospheres are selected from one or more of polystyrene nanospheres, polymethyl methacrylate nanospheres, polydopamine nanospheres, polyvinylidene fluoride nanospheres, polyethylene glycol nanospheres, chitosan nanospheres, and sodium alginate nanospheres; (3) The charged group is selected from one or more of sulfonic acid group, carboxylic acid group, amino group, quaternary ammonium salt, sulfate group, and phosphoric acid group; (4) The charged groups are modified on the surface of the organic nanospheres through chemical bonds.

6. The preparation method according to claim 1, characterized in that The drying time is 5-20 min.

7. A super hydrophilic-high oleophobic coating, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 6.

8. A super hydrophilic-high oleophobic material, characterized in that: It comprises a substrate and a coating arranged on the surface of the substrate, wherein the coating is the super hydrophilic-high oleophobic coating according to claim 7.

9. Use of the superhydrophilic-high oleophobic material according to claim 8 in oil-water separation and / or oil-proof materials.

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