An underwater superoleophobic-oleophilic porous material and its preparation method and application

Abstract

The present invention discloses an underwater superoleophobic - superhydrophilic porous material under oil and its preparation method and application, which includes the following steps: S1. Immerse a porous substrate containing hydroxyl groups in a modifier solution for surface modification to obtain a modified porous substrate; the modifier at least contains a group A capable of reacting with hydroxyl groups and a group B capable of reacting with carbon - carbon double bonds; S2. Immerse the modified porous substrate in a mixed solution containing zwitterions and / or strong ionic hydrophilic monomers, a cross - linker and an initiator for cross - linking reaction to obtain the underwater superoleophobic - superhydrophilic porous material under oil. The above - mentioned preparation method is simple in operation and easy for batch production; moreover, the underwater superoleophobic - superhydrophilic porous material prepared by the above - mentioned preparation method has controllable pore size and stable hydrophilic and oleophobic properties, and can not only be used for efficient separation of oil - water mixtures, but also has the functions of promoting dyeing and fixing color and self - cleaning ability.

Description

Technical Field

[0001] The present invention relates to the technical fields of the preparation of oil-water separation materials and fabric dyeing acceleration and fixation, and particularly relates to a preparation method of an underwater superoleophobic-oleophilic superhydrophilic porous material and its applications in aspects such as oil-water separation and fabric dyeing acceleration and fixation. Background Art

[0002] With the increase in industrial oil-containing wastewater discharge and the frequent occurrence of marine oil spills, oil-water separation has become an urgent problem to be solved. Porous membrane materials with different wettable surfaces can selectively pass oil or water and are widely used in oil-water separation. Among them, superhydrophilic-superoleophilic membrane materials can effectively separate water from oil-water mixtures after being pre-wetted with water and are widely used in the separation of emulsified oil-containing wastewater. However, since the material itself does not have oleophobicity, its surface is extremely prone to oil pollution during use, and it is difficult to remove the pollution after contamination, which will ultimately seriously affect the oil-water separation efficiency, flux and recyclability of the material.

[0003] Improving the hydrophilic and oil-repellent abilities of the membrane material to quickly repel oil on the surface and inside of the membrane in a water environment is the key to solving the membrane pollution problem. Currently, such materials are mainly realized by constructing superhydrophilic-superoleophobic interfaces in air and underwater superoleophobic-oleophilic superhydrophilic interfaces. The realization of the former oleophobicity requires fluorocarbon compounds with low surface energy. However, its persistence, bioaccumulation and toxicity have triggered strict regulation and gradual prohibition globally. The latter is mainly to construct a superhydrophilic coating by coating nanoparticles or polymers with extremely strong hydrophilicity on the substrate surface to achieve underwater superoleophobicity. The coating contains a large number of hydrophilic groups and micro-nano pores, so that oil can be displaced from the membrane surface in an oil environment to remove the oil stain on the contaminated membrane material. Superhydrophilic-superoleophobic materials are an effective way to improve the oil-water separation membrane pollution problem. Currently, the underwater superoleophobic-oleophilic superhydrophilic properties of the surface of such membrane materials mainly depend on the surface rough structure of the coating on the membrane surface and a large number of hydrophilic groups of the hydrophilic component. However, the materials prepared by the coating method currently have problems such as difficult to accurately control the pore size, lack of effective bonding between the coating on the material surface and the substrate, poor surface fastness of the material, and easy detachment of the underwater superoleophobic-oleophilic superhydrophilic component from the substrate surface during use or cleaning of the oil-water separation membrane, resulting in low oil-water separation efficiency and short service life.

[0004] Based on this, there is an urgent need for an underwater superoleophobic-oleophilic superhydrophilic membrane material with a simple preparation method, easy to control pore size and the coating is not easy to fall off, which can be used for long-term and efficient oil-water separation. Summary of the Invention

[0005] To solve the above problems, the present invention provides an underwater superoleophobic - superhydrophilic porous material under oil, a preparation method thereof and an application thereof. By using a modifier with specific groups to perform surface modification on a porous substrate and a preparation method of photo / thermal - initiated graft polymerization, hydrophilic polymer segments can be vertically anchored on the substrate surface through chemical bonds to form a high - density graft layer similar to a molecular brush, and a porous material with underwater superoleophobic and superhydrophilic under oil is constructed, realizing its stable superhydrophilic property in the oil phase. The underwater superoleophobic - superhydrophilic porous material prepared by the above method not only has controllable pore size, can be used for efficient oil - water separation, but also has a long service life; in addition, the fabric treated by the above method not only has the effect of easy removal of oil stains, but also can promote the dyeing rate of reactive dyes on the fabric and improve the soaping fastness of the dye on the fabric surface.

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

[0007] The first aspect of the present invention provides a preparation method of an underwater superoleophobic - superhydrophilic porous material, comprising the following steps:

[0008] S1. Immerse the porous substrate containing hydroxyl groups in a modifier solution for surface modification treatment to obtain a modified porous substrate;

[0009] The modifier at least contains a group A that can react with hydroxyl groups and a group B that can react with carbon - carbon double bonds;

[0010] S2. Immerse the modified porous substrate in a mixed solution containing a hydrophilic monomer, a cross - linker and an initiator for cross - linking reaction to obtain the underwater superoleophobic - superhydrophilic porous material; when the initiator is a thermal initiator, the cross - linking reaction is carried out under heating conditions; when the initiator is a photo - initiator, the cross - linking reaction is carried out under ultraviolet light irradiation conditions;

[0011] The hydrophilic monomer is an amphoteric ion and / or a strong ionic hydrophilic monomer and at least contains one carbon - carbon double bond; the cross - linker at least contains two carbon - carbon double bonds.

[0012] The present invention designs and constructs a high-density grafting layer with a molecular brush-like structure on the surface of a porous substrate through chemical bonding and crosslinking networks. After modification, the porous material can not only achieve stable underwater superoleophobicity and superhydrophilicity under oil, but also the pore size of the porous material can be precisely regulated by simply changing the pore size of the porous substrate. It can be used for long-term and efficient oil-water separation, effectively solving the problems of low oil-water separation efficiency and short service life existing in the use of existing underwater superoleophobic-superhydrophilic under-oil membrane materials as oil-water separation membranes. Specifically: The present invention uses a modifier containing a group A reactive with hydroxyl groups and a group B reactive with carbon-carbon double bonds to perform surface modification on a hydroxyl-containing porous substrate. By reacting the group A of the modifier with the hydroxyl groups on the surface of the porous substrate, the modifier is covalently modified onto the surface of the porous substrate; then, photo- or thermally initiated free radical polymerization is used. On the one hand, hydrophilic monomers and crosslinkers can form hydrophilic polymer chains, and at the same time, these hydrophilic polymer chains can react with the group B of the modifier on the surface of the porous substrate under photo- or thermal initiation, so that the hydrophilic polymer chains can be vertically anchored on the substrate surface through the modifier to form a stable, molecular brush-like high-density grafting layer; in addition, three-dimensional networks can be formed between different hydrophilic polymer chains through crosslinkers to fix the hydrophilic polymer chain segments and prevent them from swelling and falling off during use, thereby further improving the long-term stability of the surface modification layer.

[0013] In the present invention, the polymer chain segments grafted on the substrate surface through chemical grafting are orientationally ordered, and a large number of polar groups (such as amide groups, ether bonds, etc.) introduced by hydrophilic monomers are fully exposed. These groups can form a strong hydration layer with water molecules through hydrogen bonding or electrostatic interaction, significantly reducing the water contact angle and endowing the surface of the porous material with superhydrophilicity; at the same time, the chain segments with dynamic mobility in the modification layer can inhibit the adsorption of oil molecules and reduce membrane fouling, thereby achieving underwater superoleophobicity. When the porous material prepared by the present invention is immersed in oil, although non-polar oil will physically adsorb on the membrane surface, the hydrophilic groups grafted on the surface of the porous material still retain their chemical activity. The affinity of these polar groups for water molecules is much higher than that for oil molecules. Therefore, when water contacts the membrane surface, the hydrophilic groups will quickly adsorb water molecules to form a dense hydration layer, and the energy (hydrogen bonding, electrostatic interaction) released during this process is sufficient to break the weak van der Waals force between the oil molecules and the membrane surface, resulting in the oil being "squeezed out" by water molecules and detaching from the membrane surface, achieving superhydrophilicity under oil. In addition, the porous substrate modified by the modifier in the present invention can form a micro-nano rough surface through graft polymerization, combined with hydrophilic groups to produce a "superhydrophilic capillary effect", thereby further improving the oil-water separation effect and oil removal ability of the modified porous material.

[0014] Further, in step S1, the porous substrate includes a cellulose fabric, a non-woven fabric (prepared from hydroxyl group-containing fibers), or paper. The surfaces of such porous substrates contain abundant hydroxyl structures, which are conducive to the formation of a high-density grafting layer on the surface of the porous substrate after surface modification treatment and cross-linking reaction.

[0015] Further, in step S1, the group A includes one or more of siloxy groups, isocyanate groups, and epoxy groups, and the group B includes at least one of mercapto groups and carbon-carbon double bonds; preferably, the modifier is a siloxane containing a mercapto group or a double bond; more preferably, the siloxane has the following general structural formula:

[0016] ,

[0017] wherein, n is any integer from 1 to 8.

[0018] Further, in step S1, the modifier solution is obtained by dissolving the modifier in a solvent. Preferably, the solvent is selected from one or more of ethanol, methanol, acetone, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, and toluene.

[0019] Further, in step S1, the concentration of the modifier solution is preferably 1 wt% - 80 wt%, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc., including but not limited to the concentration values listed above. In the present invention, the concentration of the modifier solution affects the modification effect of the modifier on the porous substrate. If the concentration is too high or too low, due to the small content of the solvent medium or the content of the modifier, the porous substrate cannot be uniformly modified sufficiently, thereby affecting the subsequent grafting effect of the hydrophilic polymer segments on its surface. Therefore, to ensure the modification effect of the modifier on the porous substrate, preferably, the concentration of the modifier solution is controlled within the range of 1 wt% - 80 wt%.

[0020] Further, in step S1, the time for the surface modification treatment is preferably 0.2 h - 24 h, such as 0.2 h, 1 h, 2 h, 4 h, 5 h, 8 h, 10 h, 12 h, 16 h, 20 h, 24 h, etc.

[0021] Further, in step S2, the hydrophilic monomer is preferably one or more of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, carboxybetaine methacrylate, methacryloyloxyethyl phosphorylcholine, 2-acrylamido-2-methylpropane sulfonic acid, sulfopropyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, methacryloyloxyethyl trimethylammonium chloride, dimethyldiallylammonium chloride, acryloyloxyethyl trimethylammonium chloride, and sulfobetaine methacrylate.

[0022] In the present invention, the type of the hydrophilic monomer will directly affect the performance of the modified porous material. The hydrophilic groups provided by the above-mentioned hydrophilic monomers have a much higher affinity for water molecules than for oil molecules. The grafting layer formed by such hydrophilic monomers and cross-linking agents on the surface of the porous substrate can release sufficient energy to break the van der Waals force between the oil molecules in the oil and the surface of the porous material when in contact with water, thereby achieving superhydrophilicity of the modified porous material under oil.

[0023] More preferably, the hydrophilic monomer contains a group that can be protonated and positively charged at a specific pH. Such a group can adsorb negatively charged water molecules (such as OH - ), which can further increase the hydrophilicity and form an electric double layer at the oil-water interface to repel oil droplets, improving the oil-repellent effect of the modified porous material underwater.

[0024] Further, in step S2, the cross-linking agent is selected from one or more of polyethylene glycol diacrylate, N,N'-methylenebisacrylamide, pentaerythritol triallyl ether, triallyl isocyanurate, pentaerythritol tetraacrylate, polydiethylene glycol pentaacrylate, vinyl cage polyhedral oligomeric silsesquioxane, and acrylate-based cage polyhedral oligomeric silsesquioxane.

[0025] Further, in step S2, the thermal initiator is selected from one or more of benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, dimethyl 2,2'-azobis(2-methylpropionate), and 2,2'-azobis(2-amidinopropane) dihydrochloride.

[0026] Further, in step S2, the photoinitiator is selected from one or more of 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, α,α-dimethylbenzoyl ketal, benzophenone, 1-hydroxycyclohexyl phenyl ketone, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0027] Further, in step S2, the mixed solution is obtained by dissolving the hydrophilic monomer, cross-linking agent, and initiator in a solvent. Preferably, the solvent is selected from one or more of acetone, ethanol, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, and toluene.

[0028] Further, in step S2, the solid content of the mixed solution is preferably 5% - 80%, such as 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, etc.

[0029] Further, in step S2, the molar ratio of the hydrophilic monomer to the crosslinking agent is preferably (1 - 300):1, such as 2:1, 5:1, 10:1, 20:1, 30:1, 50:1, 100:1, 150:1, 200:1, 250:1, 300:1, etc., including but not limited to the molar ratios listed above. In the present invention, the ratio of the addition amounts of the hydrophilic monomer and the crosslinking agent will affect the surface hydrophilicity of the modified porous material and the stability of the modification layer. If the addition amount of the crosslinking agent is too large, the crosslinking density of the formed modification layer is too high, the molecular chain movement is restricted, and a large number of hydrophilic groups will be masked, resulting in a decrease in surface hydrophilicity. At the same time, the surface of the modification layer with too high crosslinking density is prone to embrittlement, affecting the service life of the material; however, if the addition amount of the crosslinking agent is too small, the covalent grafting rate of the hydrophilic monomer and the modified porous substrate is low, the coating is easily peeled off from the substrate surface, and the loose network cannot effectively block the penetration of oil molecules or pollutants, making the material not have the underwater super-hydrophilic property under oil; therefore, preferably, the molar ratio of the hydrophilic monomer to the crosslinking agent is controlled within the range of (1 - 300):1, so that the prepared porous material has excellent structural stability while having the characteristics of underwater super-oleophobic and super-hydrophilic under oil.

[0030] Further, in step S2, the ratio of the total mass of the hydrophilic monomer and the crosslinking agent to the mass of the initiator is (5 - 200):1, such as 5:1, 10:1, 20:1, 40:1, 60:1, 80:1, 100:1, 120:1, 140:1, 160:1, 180:1, 200:1, etc.

[0031] Further, in step S2, in the heating conditions: the heating temperature is 40 - 120 °C, and the heating time is 10 min - 240 min.

[0032] Further, in step S2, in the ultraviolet light irradiation conditions: the wavelength of the ultraviolet light is 200 - 500 nm, the irradiation intensity is 20 - 150 W / cm 2 , and the irradiation time is 5 min - 120 min.

[0033] The second aspect of the present invention provides an underwater super-oleophobic and super-hydrophilic porous material, and the underwater super-oleophobic and super-hydrophilic porous material is prepared by the preparation method described in the first aspect.

[0034] The third aspect of the present invention provides an application of an underwater superoleophobic - superhydrophilic porous material under oil in oil - water separation materials.

[0035] Furthermore, the separation efficiency of the superoleophobic - superhydrophilic porous material for oil - water mixtures can be as high as 99.9%, and the separation efficiency for water - in - oil and oil - in - water emulsions can both be as high as 99.0%.

[0036] The fourth aspect of the present invention provides an application of an underwater superoleophobic - superhydrophilic porous material under oil in easily - de - oiled materials.

[0037] The fifth aspect of the present invention provides an application of an underwater superoleophobic - superhydrophilic porous material under oil in promoting dyeing and fixing of fabrics.

[0038] When conventional cellulose fabrics are dyed, the negative charges on their surfaces will cause repulsion between reactive dyes and fibers. Usually, salt needs to be added to neutralize the charges and promote dye adsorption, but this will cause serious over - standard of chloride ion concentration, chromaticity, and COD in the dyeing wastewater, damaging the ecological environment. However, the underwater superoleophobic - superhydrophilic porous material prepared by the present invention can offset the charge repulsion between fibers and dyes in traditional dyeing through the positive charges carried by itself and the electrostatic interaction with dyes, and through the formation of a flexible polymer network after cross - linking grafting, increase the swelling property of fibers and dye permeability. At the same time, the dyes are fixed by hydrogen bonds or physical embedding, thereby effectively improving the dye uptake rate of cellulose fabrics, reducing the dependence on salt during the dyeing process of cellulose fabrics, and achieving low - salt or salt - free dyeing.

[0039] Furthermore, the underwater superoleophobic - superhydrophilic porous material prepared by ultraviolet - light initiation is placed in a solution containing reactive dyes for dyeing treatment to obtain a dyed fabric; the porous substrate of the underwater superoleophobic - superhydrophilic porous material is a cellulose fabric.

[0040] Furthermore, after the underwater superoleophobic - superhydrophilic porous material is prepared by thermal initiation, dyes are added to the mixed solution for dyeing treatment, and a dyed fabric is prepared by a one - bath method; the porous substrate of the underwater superoleophobic - superhydrophilic porous material is a cellulose fabric.

[0041] Furthermore, the dye uptake rate of the reactive dye for the underwater superoleophobic - superhydrophilic porous material can reach more than 80%, the fixation rate is not less than 70%, and the soaping fastness is grade 5.

[0042] The beneficial effects of the present invention:

[0043] 1. The present invention provides a preparation method of an underwater superoleophobic - superhydrophilic porous material under oil. Compared with the preparation of existing underwater superoleophilic - superhydrophilic materials, it is not only simple and efficient in operation, suitable for batch production; the pore structure of the underwater superoleophobic - superhydrophilic porous material prepared by the above - mentioned preparation method is easy to accurately control, has a wider selection of oil - water separation types, and the modification layer has high fastness, is not easily damaged or detached during use, and has a long service life.

[0044] 2. The underwater superoleophobic - superhydrophilic porous material provided by the present invention can not only be used for highly efficient separation of oil - water mixtures, with a separation efficiency of up to 99.9%, but also for highly efficient separation of water - in - oil or oil - in - water emulsions, and the separation efficiency of emulsions is up to 99.0%. At the same time, the porous material has self - cleaning performance, can quickly remove the oil stain on the material surface, endows the material with excellent oil - water separation performance and recyclable experimental performance, and has a broader application prospect in the field of oil - water separation.

[0045] 3. The underwater superoleophobic - superhydrophilic cellulose fabric prepared by the above method has a function of promoting dyeing and fixing color. In a salt - free process, the dyeing of reactive dyes can still achieve a dyeing effect equivalent to that of traditional dyeing processes. The dye uptake rate of reactive dye RB19 can reach 84.3%, and the color fixation rate is 75.9% (the dye uptake rate of untreated cotton fabric for the dye under the same dyeing process is 38.7%, and the color fixation rate is 23.5%; the dye uptake rate of the traditional salt - containing process is 74.6%, and the color fixation rate is 63.5%). The soaping fastness is grade 5, the dry rubbing color fastness is 4 - 5 grades, and the wet rubbing color fastness is 4 - 5 grades. Description of the Drawings

[0046] Figure 1 is the scanning electron microscope (SEM) of the modified cotton fabric prepared in Example 1 of the present invention;

[0047] Figure 2 is the contact angle test of the modified cotton fabric prepared in Example 1 of the present invention for water under oil (n - hexane);

[0048] Figure 3 is the adhesion test of the modified cotton fabric prepared in Example 1 of the present invention for the contact and detachment of oil (n - hexane) underwater;

[0049] Figure 4 is the contact angle test of the modified cotton fabric prepared in Comparative Example 2 of the present invention for water under oil (n - hexane);

[0050] Figure 5 is the contact angle test of the modified cotton fabric prepared in Comparative Example 3 of the present invention for water under oil (n - hexane);

[0051] Figure 6This is the contact angle test of the modified cotton fabric prepared in Comparative Example 4 of the present invention for water under oil (n - hexane). Detailed implementation manners

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this invention belongs. The terms used in the description of this invention herein are for the purpose of describing specific embodiments only and are not intended to limit the invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items. The "including" or "comprising" described in this invention can also be replaced by the closed - type "consisting of" or "composed of".

[0053] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the examples given are not intended to limit the present invention. Example 1

[0054] This example relates to the preparation of an underwater super - oleophobic and oil - underwater super - hydrophilic porous material, which specifically includes the following steps:

[0055] (1) Immerse the cotton fabric in an ethanol solution containing 20 wt% of 3 - mercaptopropyltriethoxysilane for 2 h, take it out, rinse it three times with ethanol to remove the free 3 - mercaptopropyltriethoxysilane on the surface, and place it in an 80 °C oven for drying to obtain the 3 - mercaptopropyltriethoxysilane - modified cotton fabric.

[0056] (2) Add the hydrophilic monomer [2 - (methacryloyloxy)ethyl]dimethyl-(3 - sulfopropyl)ammonium hydroxide, the cross - linker polyethylene glycol diacrylate, and the photo - initiator 2 - hydroxy - 4'-(2 - hydroxyethoxy)-2 - methylpropiophenone into an aqueous solution, stir at room temperature for 20 min to obtain an oil - underwater super - hydrophilic solution with a solids content of 15%. Subsequently, immerse the 3 - mercaptopropyltriethoxysilane - modified fabric in the above solution for 30 min, and transfer it to an ultraviolet light curing box for irradiation. After the irradiation, immerse the sample in deionized water for 2 h to remove the components that did not directly reach the fabric surface, and prepare the modified cotton fabric. Among them, the molar ratio of the hydrophilic monomer [2 - (methacryloyloxy)ethyl]dimethyl-(3 - sulfopropyl)ammonium hydroxide to the cross - linker polyethylene glycol diacrylate is 5:1, the wavelength of the ultraviolet light source is 365 nm, the ultraviolet light irradiation intensity is 50 W / cm 2 and the irradiation time is 15 min.

[0057] Figure 1Scanning electron micrograph of the modified cotton fabric prepared in this example. A uniform and tightly bound modification layer can be observed on the surface of the cotton fabric. The contact angle of water under oil and the contact angle of oil under water of the modified cotton fabric prepared in this example were tested, and the results are shown respectively as Figure 2 , 3 . In n-hexane, water can rapidly spread on the surface of the modified cotton fabric, and the complete spreading time is only 1 s ( Figure 2 ), showing superhydrophilic performance under oil; in addition, as can be seen from Figure 3 , the contact angle of the modified cotton fabric with n-hexane under water is greater than 150º, and the oil droplet will rapidly detach from the surface after contacting the modified cotton fabric, showing superoleophobic performance under water. It can be seen from this that the modified cotton fabric prepared in this example has the characteristics of superoleophobic under water and superhydrophilic under oil. Example 2

[0058] This example relates to the preparation of a superoleophobic under water and superhydrophilic under oil porous material. The difference from Example 1 is only that: in step (2), the hydrophilic monomer is 2-acrylamido-2-methylpropanesulfonic acid, and the other conditions are the same, and the corresponding modified cotton fabric is prepared.

[0059] The contact angle of water under oil and the contact angle of oil under water of the modified cotton fabric prepared in this example were tested, and the results showed that: in n-hexane, the complete spreading time of water is 3 s; the contact angle with n-hexane under water is greater than 150º, showing superoleophobic under water and superhydrophilic under oil performance. Example 3

[0060] This example relates to the preparation of a superoleophobic under water and superhydrophilic under oil porous material. The difference from Example 1 is only that: in step (2), the hydrophilic monomer is carboxybetaine methacrylate, and the other conditions are the same, and the corresponding modified cotton fabric is prepared.

[0061] The contact angle of water under oil and the contact angle of oil under water of the modified cotton fabric prepared in this example were tested, and the results showed that: in n-hexane, the complete spreading time of water is 3.5 s; the contact angle with n-hexane under water is greater than 150º, showing superoleophobic under water and superhydrophilic under oil performance. Example 4

[0062] This example relates to the preparation of a superoleophobic under water and superhydrophilic under oil porous material. The difference from Example 1 is only that: in step (2), the hydrophilic monomer is dimethylaminoethyl methacrylate, and the other conditions are the same, and the corresponding modified cotton fabric is prepared.

[0063] The contact angle of the modified cotton fabric prepared in this example with respect to water under oil and the contact angle with respect to oil under water were measured. The results showed that in n-hexane, the complete spreading time of water was 7 s; the contact angle with respect to n-hexane under water was greater than 150°, showing underwater superoleophobic-superhydrophilic performance under oil. Example 5

[0064] This example relates to the preparation of an underwater superoleophobic-superhydrophilic porous material. The difference from Example 1 is only that: in step (2), the molar ratio of the hydrophilic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide to the crosslinking agent polyethylene glycol diacrylate is 1:1, and the other conditions are the same, and the corresponding modified cotton fabric was prepared.

[0065] The contact angle of the modified cotton fabric prepared in this example with respect to water under oil and the contact angle with respect to oil under water were measured. The results showed that in n-hexane, the complete spreading time of water was 21 s; the contact angle with respect to n-hexane under water was greater than 150°, showing underwater superoleophobic-superhydrophilic performance under oil. Example 6

[0066] This example relates to the preparation of an underwater superoleophobic-superhydrophilic porous material. The difference from Example 1 is only that: in step (2), the molar ratio of the hydrophilic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide to the crosslinking agent polyethylene glycol diacrylate is 30:1, and the other conditions are the same, and the corresponding modified cotton fabric was prepared.

[0067] The contact angle of the modified cotton fabric prepared in this example with respect to water under oil and the contact angle with respect to oil under water were measured. The results showed that in n-hexane, the complete spreading time of water was 35 s; the contact angle with respect to n-hexane under water was greater than 150°, showing underwater superoleophobic-superhydrophilic performance under oil. Example 7

[0068] This example relates to the preparation of an underwater superoleophobic-superhydrophilic porous material. The difference from Example 1 is only that: in step (2), the crosslinking agent is N,N'-methylenebisacrylamide, and the other conditions are the same, and the corresponding modified cotton fabric was prepared.

[0069] The contact angle of the modified cotton fabric prepared in this example with respect to water under oil and the contact angle with respect to oil under water were measured. The results showed that in n-hexane, the complete spreading time of water was 4 s; the contact angle with respect to n-hexane under water was greater than 150°, showing underwater superoleophobic-superhydrophilic performance under oil. Example 8

[0070] This example relates to the preparation of an underwater superoleophobic-oleophobic and superhydrophilic porous material. The difference from Example 1 is only that: in step (2), the crosslinking agent is acrylate-based cage-like polyhedral oligomeric silsesquioxane, the solvent is acetone, and the molar ratio of the hydrophilic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide to the crosslinking agent acrylate-based cage-like polyhedral oligomeric silsesquioxane is 50:1. Under other identical conditions, the corresponding modified cotton fabric is prepared.

[0071] The contact angle of the modified cotton fabric prepared in this example with respect to water under oil and the contact angle with respect to oil underwater were tested. The results showed that: in n-hexane, the complete spreading time of water was 9 s; the contact angle with respect to n-hexane underwater was greater than 150º, showing underwater superoleophobic-oleophobic and superhydrophilic properties. Example 9

[0072] This example relates to the preparation of an underwater superoleophobic-oleophobic and superhydrophilic porous material. The difference from Example 4 is only that: in step (2), a thermal initiator is used to initiate the crosslinking reaction, specifically as follows:

[0073] (1) Immerse the cotton fabric in an ethanol solution containing 20 wt% of 3-mercaptopropyltriethoxysilane for 2 h, take it out, rinse it three times with ethanol to remove the free 3-mercaptopropyltriethoxysilane on the surface, and place it in an 80 °C oven to dry, obtaining the cotton fabric modified with 3-mercaptopropyltriethoxysilane.

[0074] (2) Add the hydrophilic monomer dimethylaminoethyl methacrylate, the crosslinking agent polyethylene glycol diacrylate, and the thermal initiator azobisisobutyronitrile to an aqueous solution, and stir at room temperature for 20 min to obtain an oil-superhydrophilic solution with a solids content of 8%. Among them, the molar ratio of the hydrophilic monomer dimethylaminoethyl methacrylate to the crosslinking agent polyethylene glycol diacrylate is 5:1. Immerse the fabric modified with 3-mercaptopropyltriethoxysilane in the above solution, and heat it to 80 °C and stir for 1 h to obtain the modified cotton fabric.

[0075] The contact angle of the modified cotton fabric prepared in this example with respect to water under oil and the contact angle with respect to oil underwater were tested. The results showed that: in n-hexane, the complete spreading time of water was 10 s; the contact angle with respect to n-hexane underwater was greater than 150º, showing underwater superoleophobic-oleophobic and superhydrophilic properties. Comparative Example 1

[0076] This comparative example relates to the preparation of an underwater superoleophobic-oleophobic and superhydrophilic porous material. The difference from Example 4 is only that: the fabric was not modified with siloxane, and other conditions were the same, and the corresponding modified cotton fabric was prepared.

[0077] The contact angle of the modified cotton fabric prepared in this comparative example with respect to water under oil and the contact angle with respect to oil under water were tested. The results showed that in n-hexane, the complete spreading time of water was 13 s; the contact angle with respect to n-hexane under water was greater than 150°, showing underwater superoleophobic-superhydrophilic performance under oil. Comparative Example 2

[0078] This comparative example relates to the preparation of an underwater superoleophobic-superhydrophilic porous material. The difference from Example 4 is only that: in step (2), the hydrophilic monomer is acrylamide, and the other conditions are the same, and the corresponding modified cotton fabric was prepared.

[0079] The contact angle of the modified cotton fabric prepared in this comparative example with respect to water under oil and the contact angle with respect to oil under water were tested. The results showed that in n-hexane, the contact angle of water was 152°; the contact angle with respect to n-hexane under water was greater than 150°, showing underwater superoleophobic-superhydrophilic performance under oil. Comparative Example 3

[0080] This comparative example relates to the preparation of an underwater superoleophobic-superhydrophilic porous material. The difference from Example 4 is only that: in step (2), the hydrophilic monomer is methacrylic acid, and the other conditions are the same, and the corresponding modified cotton fabric was prepared.

[0081] The contact angle of the modified cotton fabric prepared in this comparative example with respect to water under oil and the contact angle with respect to oil under water were tested. The results showed that in n-hexane, the contact angle of water was 155°; the contact angle with respect to n-hexane under water was greater than 150°, showing underwater superoleophobic-superhydrophilic performance under oil. Comparative Example 4

[0082] This comparative example relates to the preparation of an underwater superoleophobic-superhydrophilic porous material. The difference from Example 1 is only that: in step (2), there is no crosslinking agent, and the other conditions are the same, and the corresponding modified cotton fabric was prepared.

[0083] The contact angle of the modified cotton fabric prepared in this comparative example with respect to water under oil and the contact angle with respect to oil under water were tested. The results showed that in n-hexane, the contact angle of water was 140°; the contact angle with respect to n-hexane under water was greater than 150°, showing underwater superoleophobic-superhydrophilic performance under oil.

[0084] The test results of the contact angles of the modified cotton fabrics prepared in the above examples and comparative examples with respect to water (under oil) and oil (under water) are shown in Table 1 below:

[0085] Table 1

[0086]

[0087] Application Example 1

[0088] The modified cotton fabrics prepared in Example 1 and Comparative Example 1 were named modified cotton fabric 1 and 2 respectively. The separation efficiency, separation flux and durability of the oil-water mixture were tested using modified cotton fabric 1 and 2 respectively. In addition, the cotton fiber felts were modified by the methods in Example 1 and Comparative Example 1 respectively to obtain the corresponding modified cotton fiber felts 1 and 2. Then, the separation efficiency, separation flux and durability of the water-in-oil emulsion and oil-in-water emulsion were tested using modified cotton fiber felts 1 and 2 respectively. The test procedures are as follows:

[0089] Preparation of the oil-water mixture: 50 g of water and 50 g of n-hexane were mixed to prepare an oil-water mixture.

[0090] Test method for the separation efficiency of the oil-water mixture: Weigh the weight of the separated oil by a balance, and calculate the separation efficiency of the oil-water mixture according to the formula 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.

[0091] Preparation of the water-in-oil emulsion: 0.2 g of Span 80, 2 g of water and 100 g of diesel were ultrasonically treated in an ultrasonic cleaner for 24 h to form a stable emulsion. The prepared emulsion remained stable for at least 48 h.

[0092] Test method for the separation efficiency of the water-in-oil emulsion: The test instrument was a trace moisture tester (Zibo Zifen Instrument Co., Ltd.); 1 mL of the filtrate before filtration and the filtrate after filtration were taken, and the initial concentration of water in the emulsion before treatment and the residual concentration of water in the oil phase after filtration were measured as C0 and C1 (unit: ppm) respectively. Finally, the separation efficiency was calculated according to the formula .

[0093] Preparation of the oil-in-water emulsion: 1 g of Tween 80, 500 g of water and 10 g of diesel were ultrasonically treated in an ultrasonic cleaner for 24 h to form a stable emulsion. The prepared emulsion remained stable for at least 48 h.

[0094] Test method for the separation efficiency of the oil-in-water emulsion: The test instrument was an infrared oil analyzer (Qingdao Juchuang Environmental Protection Group Co., Ltd.); 100 mL of the filtrate before filtration and the filtrate after filtration were taken, and the treated extraction solution was injected into a quartz cuvette and placed in the sample cell of the instrument. 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 water phase after filtration were measured as C0 and C1 (unit: ppm) respectively. Finally, according to , the separation efficiency was calculated.

[0095] Test method for the separation flux: The volume of the permeate passing through a unit membrane area per unit time, according to the formula Calculate the separation flux J, where V is the volume of the permeate in liters (L); A is the effective membrane area in square meters (m 2 ; t is the operating time in hours (h).

[0096] Test method for durability: Repeat the above separation operation 10 times for the above oil-water mixture, water-in-oil emulsion, and oil-in-water emulsion, and calculate the separation efficiency corresponding after 10 cycles.

[0097] The above test results are shown in Table 2 below:

[0098] Table 2

[0099]

[0100] As can be seen from Table 2, the initial separation efficiency of the modified cotton fabric 1 prepared in Example 1 for the oil-water mixture is comparable to that of the modified cotton fabric 2, but its separation flux for the oil-water mixture is significantly improved. Moreover, after 10 cycles, the separation efficiency of the modified cotton fabric 1 for the oil-water mixture can still reach 98.1%. However, for the modified cotton fabric 2, due to the shedding of the surface coating after the cyclic separation operation, both oil and water can pass through during the 10th separation, thus failing to achieve oil-water separation.

[0101] In addition, the cotton fiber felt was modified by the methods in Example 1 and Comparative Example 1 to obtain the corresponding modified cotton fiber felts 1 and 2. Their initial separation efficiencies for the water-in-oil emulsion are comparable, and the initial separation efficiency of the modified cotton fiber felt 1 for the oil-in-water emulsion is better. More importantly, compared with the modified cotton fiber felt 2, the modified cotton fiber felt 1 has significantly higher separation fluxes for the water-in-oil emulsion and the oil-in-water emulsion, and can still maintain a high separation efficiency after 10 cycles, showing excellent durability.

[0102] Application Example 2

[0103] Taking the modified cotton fabric prepared in Example 9 as an example, it is used for fabric dyeing acceleration and fixation. The specific operation is as follows:

[0104] After the heating and stirring reaction in step (2) of Example 9, the solution is cooled to 30 °C, and then the pH value of the solution is adjusted to 5 - 6. Subsequently, the reactive dye RB19 is added and stirred evenly, and then kept warm for 30 min. Then, it is heated to 60 °C at a rate of 2 °C / min, and 10 g / L of anhydrous Na2CO3 is added and kept warm for fixation for 60 min. After dyeing, the fabric is repeatedly rinsed with distilled water on both sides, and then the cloth sample is put into the soaping solution for washing and drying to obtain the dyed modified cotton fabric. Among them, the dosage of the dye RB19 is 2% (owf), the bath ratio for dyeing is 20:1, and the soaping conditions are: bath ratio 20:1, concentration 2 g / L, temperature 95 °C, and full soaping for 10 min.

[0105] For comparison, salt-free dyeing and traditional dyeing were carried out on untreated cotton fabrics.

[0106] Salt-free dyeing of untreated cotton fabric: Adjust the pH value of the pre-prepared dye solution to 5-6, heat it up to the predetermined temperature, put the fabric into the dye bath, after keeping warm for the predetermined time, heat it up to 60 °C at a rate of 2 °C / min, add 10 g / L of anhydrous Na2CO3, and keep warm for fixation for 60 min. After the dyeing is completed, repeatedly rinse the front and back of the fabric with distilled water, and then put the fabric sample into the soaping solution for washing and drying to obtain the dyed modified cotton fabric. Among them, the dosage of dye RB19 is 2% (owf), the bath ratio is 20:1 for dyeing, and the soaping conditions are: bath ratio 20:1, concentration 2 g / L, temperature 95 °C, and full soaping for 10 min.

[0107] Traditional salt dyeing: Heat up the pre-prepared dye solution to 30 °C, put the fabric into the dye bath, add 60 g of NaCl after keeping warm for 15 min, continue dyeing for 15 min, then heat it up to 60 °C at a rate of 2 °C / min, add 10 g / L of anhydrous Na2CO3, and keep warm for fixation for 60 min. After the dyeing is completed, repeatedly rinse the front and back of the fabric with distilled water and then put the fabric sample into the soaping solution. Among them, the dosage of dye RB19 is 2% (owf), the bath ratio is 20:1 for dyeing, and the soaping conditions are: bath ratio 20:1, concentration 2 g, temperature 95 °C, and full soaping for 10 min.

[0108] The test results of fabric dyeing treatment by different processes are as follows: Using the modified cotton fabric prepared in Example 9 for salt-free dyeing, the dye uptake rate of RB19 can reach 84.3%, the fixation rate is 75.9%, the soaping fastness is 4-5 grades, the dry rubbing color fastness is 4-5 grades, and the wet rubbing color fastness is 4 grades. For the untreated fabric with salt-free dyeing, the dye uptake rate of RB19 is only 38.7%, the fixation rate is 23.5%, the soaping fastness is 3-4 grades, the dry rubbing color fastness is 4 grades, and the wet rubbing color fastness is 3 grades. For the untreated cotton fabric with traditional salt dyeing, the dye uptake rate is 74.6%, the fixation rate is 63.5%, the soaping fastness is 4-5 grades, the dry rubbing color fastness is 4-5 grades, and the wet rubbing color fastness is 3-4 grades. It can be seen that the dye uptake rate and fixation rate of the cotton fabric treated by the modification of the present invention for salt-free dyeing are significantly better than those of the untreated fabric for salt-free / salt dyeing, and the soaping fastness, dry rubbing color fastness and wet rubbing color fastness are higher.

[0109] The above-mentioned embodiments are only preferred embodiments given to fully illustrate the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention is subject to the claims.

Claims

1. A preparation method of an underwater superoleophobic and underwater superhydrophilic porous material, characterized in that, It includes the following steps: S1. Immerse the hydroxyl-containing porous substrate in the modifier solution for surface modification treatment to obtain a modified porous substrate; The modifier at least contains a group A that can react with hydroxyl groups and a group B that can react with carbon-carbon double bonds; S2. Immerse the modified porous substrate in a mixed solution containing a hydrophilic monomer, a crosslinking agent, and an initiator for crosslinking reaction to obtain the underwater superoleophobic and oil-underwater superhydrophilic porous material; when the initiator is a thermal initiator, the crosslinking reaction is carried out under heating conditions; when the initiator is a photoinitiator, the crosslinking reaction is carried out under ultraviolet light irradiation conditions; The hydrophilic monomer is selected from one or more of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, carboxybetaine methacrylate, methacryloyloxyethyl phosphorylcholine, 2-acrylamido-2-methylpropanesulfonic acid, sulfopropyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, methacryloyloxyethyl trimethylammonium chloride, dimethyldiallylammonium chloride, acryloyloxyethyl trimethylammonium chloride, and sulfobetaine methacrylate; The crosslinking agent is selected from one or more of polyethylene glycol diacrylate, N,N'-methylenebisacrylamide, pentaerythritol triallyl ether, triallyl isocyanurate, pentaerythritol tetraacrylate, polydi(ethylene glycol) pentaacrylate, vinyl caged polysilsesquioxane, and acrylate caged polysilsesquioxane; 2. The preparation method according to claim 1, characterized in that, In step S1, the porous substrate includes a cellulose fabric, a nonwoven fabric, or paper; The group A includes one or more of a siloxy group, an isocyanate group, and an epoxy group, and the group B includes at least one of a mercapto group and a carbon-carbon double bond.

3. The preparation method according to claim 2, characterized in that, The modifier is a siloxane containing a mercapto group or a carbon-carbon double bond.

4. The preparation method according to claim 1, characterized in that, In step S1, it at least includes one of the following features: (1) The modifier solution is obtained by dissolving the modifier in a solvent, and the solvent is selected from one or more of ethanol, methanol, acetone, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, and toluene; (2) The concentration of the modifier solution is 5 wt%-50 wt%; (3) The time of the surface modification treatment is 0.2-24 h.

5. The preparation method according to claim 1, wherein In step S2, the thermal initiator is selected from one or more of benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, dimethyl azobisisobutyrate, and 2,2'-azobis(2-amidinopropane) dihydrochloride; The photoinitiator is selected from one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, α,α'-dimethylbenzoyl ketal, benzophenone, 1-hydroxycyclohexyl phenyl ketone, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide; 6. The preparation method according to claim 1, characterized in that, In step S2, it at least includes one of the following features: (1) The mixed solution is obtained by dissolving the hydrophilic monomer, the crosslinking agent, and the initiator in a solvent, and the solvent is selected from one or more of acetone, ethanol, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, and toluene; (2) The solid content of the mixed solution is 5%-80%; (3) The molar ratio of the hydrophilic monomer to the crosslinking agent is (1-300):1; (4) The ratio of the total mass of the hydrophilic monomer and the crosslinking agent to the mass of the initiator is (5-200):1; (5) In the heating conditions: the heating temperature is 40-120 °C, and the heating time is 10 min-240 min; In the ultraviolet light irradiation conditions: the wavelength of the ultraviolet light is 200 - 500 nm, the irradiation intensity is 20 - 150 W / cm 2 , and the irradiation time is 5 min - 120 min.

7. An underwater superoleophobic-oleophilic porous material, characterized in that, The underwater superoleophobic-above-oil superhydrophilic porous material is prepared by the preparation method according to any one of claims 1-6.

8. An application of the underwater superoleophobic-above-oil superhydrophilic porous material according to claim 7 in the aspect of oil-water separation materials.

9. An application of the underwater superoleophobic-above-oil superhydrophilic porous material according to claim 7 in the aspect of easily deoiling materials.

10. An application of the underwater superoleophobic-above-oil superhydrophilic porous material according to claim 7 in the aspect of promoting dyeing and fixing color of fabrics.

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