Underwater super-oleophobic-under-oil super-hydrophilic porous material as well as preparation method and application thereof

Abstract

The invention discloses an underwater super-oleophobic-under-oil super-hydrophilic porous material and a preparation method and application thereof.The preparation method comprises the following steps that S1, a porous base material containing hydroxyl is soaked in a modifier solution for surface modification, and a modified porous base material is obtained; the modifier at least comprises a group A capable of reacting with hydroxyl and a group B capable of reacting with carbon-carbon double bonds; and S2, dipping the modified porous base material in a mixed solution containing zwitterionic and / or strong ionic hydrophilic monomers, a cross-linking agent and an initiator, and carrying out a cross-linking reaction to obtain the underwater super-oleophobic-under-oil super-hydrophilic porous material. The preparation method is simple to operate and easy for batch production; the underwater super-oleophobic-under-oil super-hydrophilic porous material prepared by the preparation method is controllable in pore size and stable in hydrophilic and oleophobic performance, not only can be used for efficiently separating an oil-water mixture, but also has a dyeing accelerating and color fixing function and a self-cleaning capability.

Description

Technical Field

[0001] The present invention relates to the technical field of oil-water separation material preparation and fabric dyeing and color fixation, and in particular to a method for preparing an underwater super-oleophobic-under-oil super-hydrophilic porous material, and its application in oil-water separation, fabric dyeing and color fixation, etc. Background Art

[0002] With the increase in industrial oily wastewater discharge and the frequent occurrence of marine oil spills, oil-water separation has become an urgent problem that needs 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 separation of emulsified oily wastewater. However, since the material itself is not oleophobic, the surface is easily contaminated by oil during use, and it is difficult to remove the contamination, which will eventually seriously affect the efficiency, flux and recyclability of the material's oil-water separation.

[0003] Improving the hydrophilicity and oil repellency of membrane materials, so that the membrane materials can quickly repel oil on the membrane surface and inside in a water environment, is the key to solving the membrane fouling problem. At present, such materials are mainly realized by constructing super-hydrophilic-super-oleophobic interfaces in the air and super-oleophobic-super-hydrophilic interfaces under water. The former requires low surface energy fluorocarbon compounds to achieve oleophobicity. However, its persistence, bioaccumulation and toxicity have triggered strict supervision and gradual banning worldwide. The latter is mainly achieved by coating highly hydrophilic nanoparticles or polymers on the surface of the substrate to construct a super-hydrophilic coating to achieve underwater super-oleophobicity. The coating contains a large number of hydrophilic groups and micro-nano pores, so that the oil can be displaced from the membrane surface in an oil environment, and the oil stains of the contaminated membrane material can be removed. Super-hydrophilic-super-oleophobic materials are an effective way to improve the fouling problem of oil-water separation membranes. At present, the underwater super-oleophobic-super-hydrophilic properties of the surface of such membrane materials mainly depend on the rough surface structure of the coating and the large number of hydrophilic groups of the hydrophilic components on the membrane surface. However, the materials currently prepared by the coating method have pore sizes that are difficult to precisely control, lack of effective bonding between the surface coating and the substrate, and poor surface fastness of the material. When used as an oil-water separation membrane, the underwater superoleophobic-under-oil superhydrophilic components are easily detached from the substrate surface during use or cleaning, resulting in low oil-water separation efficiency and short service life.

[0004] Based on this, there is an urgent need for an underwater superoleophobic-under-oil superhydrophilic membrane material with a simple preparation method, easily adjustable pore size and non-removable coating, which can be used for long-term and efficient separation of oil and water. Summary of the invention

[0005] To solve the above problems, the present invention provides an underwater super oleophobic-oil super hydrophilic porous material and its preparation method and application, by using a modifier with a specific group to perform surface modification treatment on a porous substrate and using a preparation method of light / heat-induced graft polymerization, so that the hydrophilic polymer chain segment can be vertically anchored on the substrate surface through chemical bonds, forming a high-density grafting layer similar to a molecular brush, and constructing a porous material with underwater super oleophobicity and oil super hydrophilicity, and realizing its stable super hydrophilic property in the oil phase. The underwater super oleophobic-oil super hydrophilic porous material prepared by the above method not only has controllable pore size, can be used for efficient separation of oil and water, and has a long service life; in addition, the fabric treated by the above method not only has the effect of easy degreasing, but also can promote the dyeing rate of reactive dyes on fabrics, and improve the soaping fastness of dyes on the fabric surface.

[0006] Specifically, the following technical solutions are provided: The first aspect of the present invention provides a method for preparing an underwater super oleophobic-under-oil super hydrophilic porous material, comprising the following steps: S1, immersing the hydroxyl-containing porous substrate in a modifier solution to perform surface modification treatment to obtain a modified porous substrate; The modifier at least comprises a group A that can react with a hydroxyl group and a group B that can react with a carbon-carbon double bond; S2, immersing the modified porous substrate in a mixed solution comprising a hydrophilic monomer, a crosslinking agent and an initiator, and performing a crosslinking reaction to obtain the underwater superoleophobic-under-oil superhydrophilic porous material; when the initiator is a thermal initiator, the crosslinking reaction is performed under heating conditions; when the initiator is a photoinitiator, the crosslinking reaction is performed under ultraviolet light irradiation conditions; The hydrophilic monomer is a zwitterionic and / or strongly ionic hydrophilic monomer and contains at least one carbon-carbon double bond; the crosslinking agent contains at least two carbon-carbon double bonds.

[0007] The present invention designs and constructs a high-density grafted layer similar to a molecular brush on the surface of a porous substrate through chemical bonding and a cross-linked network, so that the modified porous material can not only achieve stable underwater superoleophobic and sub-oil superhydrophilic properties, but also the pore size of the porous material can be precisely controlled by simply changing the pore size of the porous substrate, and can be used for long-term and efficient separation of oil and water, effectively solving the problems of low oil-water separation efficiency and short service life when the existing underwater superoleophobic-sub-oil superhydrophilic membrane materials are used as oil-water separation membranes. Specifically: the present invention uses a modifier containing a group A that can react with a hydroxyl group and a group B that can react with a carbon-carbon double bond to perform surface modification treatment on a hydroxyl-containing porous substrate, and the modifier is modified to the surface of the porous substrate through covalent bonds by reacting the group A of the modifier with the hydroxyl group on the surface of the porous substrate; then light or heat is used to initiate free radical polymerization, so that on the one hand, the hydrophilic monomer and the crosslinking agent can form a hydrophilic polymer chain, and at the same time, the hydrophilic polymer chain can react with the group B of the porous substrate surface modifier under the action of light or heat, so that the hydrophilic polymer chain can be vertically anchored on the substrate surface through the modifier to form a stable, high-density grafted layer similar to a molecular brush; in addition, different hydrophilic polymer chains can form a three-dimensional network through the crosslinking agent to fix the hydrophilic polymer chain segments to prevent them from swelling and falling off during use, thereby further improving the long-term stability of the surface modification layer.

[0008] In the present invention, the polymer chain segments chemically grafted on the surface of the substrate are oriented in an orderly manner, and a large number of polar groups (such as amide groups, ether bonds, etc.) introduced by the hydrophilic monomers are fully exposed. These groups can form a strong hydration layer with water molecules through hydrogen bonds or electrostatic interactions, significantly reducing the water contact angle, and giving the porous material surface super-hydrophilicity; at the same time, the segments with dynamic mobility in the modified layer can inhibit the adsorption of oil molecules and reduce membrane pollution, thereby achieving underwater super-oleophobic properties. When the porous material prepared by the present invention is immersed in oil, although the non-polar oil will be physically adsorbed 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 of oil molecules, so that when water contacts the membrane surface, the hydrophilic groups will quickly adsorb water molecules to form a dense hydration layer. The energy released in this process (hydrogen bonds, electrostatic effects) is sufficient to destroy the weak van der Waals force between the oil molecules and the membrane surface, causing the oil to be "occupied" by water molecules and detach from the membrane surface, achieving super-hydrophilic properties under oil. In addition, the porous substrate modified by the modifier of the present invention can form a micro-nano rough surface through graft polymerization, and produce a "superhydrophilic capillary effect" in combination with the hydrophilic group, thereby further improving the oil-water separation effect and oil removal ability of the modified porous material.

[0009] Furthermore, in step S1, the porous substrate includes cellulose fabric, non-manufactured cloth (prepared from hydroxyl-containing fibers) or paper. The surface of such porous substrate contains abundant hydroxyl structures, which is conducive to forming a high-density grafted layer on the surface of the porous substrate after surface modification and cross-linking reaction.

[0010] Further, in step S1, 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; preferably, the modifier is a siloxane containing a mercapto group or a double bond; more preferably, the siloxane has the following general structural formula: , Wherein, n is any integer from 1 to 8.

[0011] Furthermore, in step S1, the modifier solution is obtained by dissolving the modifier in a solvent, and preferably, the solvent is selected from one or more of ethanol, methanol, acetone, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, and toluene.

[0012] 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 above-mentioned concentration values. In the present invention, the concentration of the modifier solution will affect the modification effect of the modifier on the porous substrate. If the concentration is too high or too low, the porous substrate cannot be fully and uniformly modified due to the low content of the solvent medium or the content of the modifier, thereby affecting the subsequent grafting effect of the hydrophilic polymer chain segment on its surface. Therefore, in order to ensure the modification effect of the modifier on the porous substrate, preferably, the concentration of the modifier solution is controlled in the range of 1 wt%-80 wt%.

[0013] Furthermore, in step S1, the surface modification treatment time is preferably 0.2 h-24 h, for example, 0.2 h, 1 h, 2 h, 4 h, 5 h, 8 h, 10 h, 12 h, 16 h, 20 h, 24 h, etc.

[0014] Further, in step S2, the hydrophilic monomer is preferably one or more of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonatepropyl)ammonium hydroxide, carboxy betaine methacrylate, methacryloyloxyethyl phosphorylcholine, 2-acrylamido-2-methylpropane sulfonic acid, sulfopropyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, methacryloyloxyethyltrimethylammonium chloride, dimethyldiallylammonium chloride, acryloyloxyethyltrimethylammonium chloride, and sulfobetaine methacrylate.

[0015] In the present invention, the type of hydrophilic monomer will directly affect the performance of the modified porous material. The hydrophilic group provided by the hydrophilic monomer has a much higher affinity for water molecules than for oil molecules. The grafted layer formed by such hydrophilic monomer and cross-linking agent on the surface of the porous substrate can release enough energy to destroy 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 the super hydrophilicity of the modified porous material under oil.

[0016] More preferably, the hydrophilic monomer comprises a positively charged group that can be protonated at a specific pH, and such a group can adsorb negatively charged water molecules (such as OH) by electrostatic interaction. - ), which can further increase the hydrophilicity and form a double electric layer at the oil-water interface to repel oil droplets, thereby improving the oleophobic effect of the modified porous material underwater.

[0017] Further, in step S2, the crosslinking agent is selected from one or more of polyethylene glycol diacrylate, N,N'-methylenebisacrylamide, pentaerythritol triallyl ether, triallyl isocyanurate, pentaerythritol tetraacrylate, polydipentaerythritol pentaacrylate, vinyl cage polysilsesquioxane and acrylate cage polysilsesquioxane.

[0018] Furthermore, in step S2, the thermal initiator is selected from one or more of dibenzoyl peroxide, dilauroyl peroxide, azobisisobutyronitrile, dimethyl azobisisobutyrate, and 2,2'-azobis(2-amidinopropane) dihydrochloride.

[0019] Further, in step S2, the photoinitiator is selected from one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, a,a,-dimethylbenzil ketal, benzophenone, 1-hydroxycyclohexyl benzophenone and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0020] Furthermore, in step S2, the mixed solution is obtained by dissolving a hydrophilic monomer, a cross-linking agent and an initiator in a solvent. Preferably, the solvent is selected from one or more of acetone, ethanol, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide and toluene.

[0021] Furthermore, in step S2, the solid content of the mixed solution is preferably 5%-80%, for example, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, etc.

[0022] Furthermore, in step S2, the molar ratio of the hydrophilic monomer to the cross-linking agent is preferably (1-300):1, for example 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 amount of hydrophilic monomer to the amount of cross-linking agent added will affect the surface hydrophilicity of the modified porous material and the stability of the modified layer. If the amount of cross-linking agent added is too much, the cross-linking density of the modified layer formed is too high, the movement of the molecular chain is restricted and a large number of hydrophilic groups will be masked, thereby resulting in a decrease in surface hydrophilicity. At the same time, the surface of the modified layer with too high a cross-linking density is prone to brittleness, affecting the service life of the material; but if the amount of cross-linking agent added is too little, the covalent grafting rate of the hydrophilic monomer to the modified porous substrate is low, the coating is easily peeled off from the surface of the substrate, and the loose network cannot effectively block the penetration of oil molecules or pollutants, so that the material does not have super hydrophilic properties under oil; therefore, preferably, the molar ratio of the hydrophilic monomer to the cross-linking agent is controlled in the range of (1-300): 1, so that the prepared porous material has both underwater super oleophobicity and super hydrophilicity under oil and excellent structural stability.

[0023] Furthermore, in step S2, the ratio of the total mass of the hydrophilic monomer and the cross-linking agent to the mass of the initiator is (5-200):1, for example, 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.

[0024] Furthermore, in step S2, the heating conditions are: the heating temperature is 40-120° C., and the heating time is 10 min-240 min.

[0025] Furthermore, in step S2, the ultraviolet light irradiation conditions are: the wavelength of the ultraviolet light is 200-500 nm, and the irradiation intensity is 20-150 W / cm 2 The irradiation time is 5 min-120 min.

[0026] The second aspect of the present invention provides an underwater super oleophobic-under-oil super hydrophilic porous material, and the underwater super oleophobic-under-oil super hydrophilic porous material is prepared by the preparation method described in the first aspect.

[0027] The third aspect of the present invention provides an application of an underwater superoleophobic-under-oil superhydrophilic porous material in oil-water separation materials.

[0028] Furthermore, the superoleophobic-superhydrophilic-under-oil porous material can achieve a separation efficiency of up to 99.9% for oil-water mixtures, and a separation efficiency of up to 99.0% for water-in-oil and water-oil emulsions.

[0029] A fourth aspect of the present invention provides an application of an underwater super oleophobic-under-oil super hydrophilic porous material in a material that is easy to remove oil stains.

[0030] A fifth aspect of the present invention provides an application of an underwater superoleophobic-under-oil superhydrophilic porous material in promoting dyeing and fixing of fabrics.

[0031] When conventional cellulose fabrics are dyed, the negative charge on their surface will lead to repulsion between active dyes and fibers, and salt is usually needed to neutralize the charge and promote dye adsorption, but this will cause the chloride ion concentration, chromaticity and COD in the dyeing wastewater to seriously exceed the standard, damaging the ecological environment. The underwater super oleophobic-oil super hydrophilic porous material prepared by the present invention can offset the charge repulsion between fibers and dyes in traditional dyeing through its own positive charge and electrostatic interaction with the dye, and form a flexible polymer network after cross-linking and grafting, increase the swelling and dye permeability of the fiber, and fix the dye by hydrogen bonding or physical embedding, thereby effectively improving the dye uptake of cellulose fabrics, reducing the dependence on salt in the dyeing process of cellulose fabrics, and achieving low-salt or salt-free dyeing.

[0032] Furthermore, the underwater superoleophobic-under-oil superhydrophilic porous material prepared by ultraviolet light initiation is placed in a solution containing active dyes for dyeing to obtain a dyed fabric; the porous substrate of the underwater superoleophobic-under-oil superhydrophilic porous material is a cellulose fabric.

[0033] Furthermore, after the underwater superoleophobic-under-oil superhydrophilic porous material is prepared by thermal initiation, a dye is added to the mixed solution for dyeing, and the dyed fabric is prepared by a one-bath method; the porous substrate of the underwater superoleophobic-under-oil superhydrophilic porous material is cellulose fabric.

[0034] Furthermore, the dyeing rate of the reactive dye on the underwater superoleophobic-under-oil superhydrophilic porous material can reach more than 80%, the color fixation rate is not less than 70%, and the soap fastness is level 5.

[0035] Beneficial effects of the present invention: 1. The present invention provides a method for preparing an underwater super oleophobic-under-oil super hydrophilic porous material. Compared with the preparation method of the existing underwater super oleophilic-under-oil super hydrophilic material, the method is not only simple to operate and efficient, but also suitable for mass production; the pore structure of the underwater super oleophobic-under-oil super hydrophilic porous material prepared by the above preparation method is easy to accurately control, the type of oil-water separation is wider, and the modified layer has high fastness, is not easy to be damaged or fall off during use, and has a long service life.

[0036] 2. The underwater superoleophobic-under-oil superhydrophilic porous material provided by the present invention can not only be used for efficient separation of oil-water mixtures, with a separation efficiency of up to 99.9%, but can also be used for efficient separation of water-in-oil or oil-in-water emulsions, with a separation efficiency of up to 99.0% for the emulsions. At the same time, the porous material has a self-cleaning property, which can quickly remove oil stains on the surface of the material, giving the material excellent oil-water separation performance and recyclable experimental performance, and has a broader application prospect in the field of oil-water separation.

[0037] 3. The underwater superoleophobic-oil superhydrophilic cellulose fabric prepared by the above method has the function of promoting dyeing and fixing color. The dyeing of reactive dyes in the salt-free process can still achieve the dyeing effect equivalent to that of the traditional dyeing process. The dyeing rate of the reactive dye RB19 can reach 84.3%, and the fixation rate is 75.9% (the dyeing rate of the untreated cotton fabric under the same dyeing process is 38.7%, and the fixation rate is 23.5%; the dyeing rate of the traditional salt process is 74.6%, and the fixation rate is 63.5%). The soap fastness is level 5, the dry friction color fastness is level 4-5, and the wet friction color fastness is level 4-5. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a scanning electron microscope (SEM) of the modified cotton fabric prepared in Example 1 of the present invention; Figure 2 The contact angle test of the modified cotton fabric prepared in Example 1 of the present invention on water under oil (n-hexane); Figure 3 It is a test of the adhesion of the modified cotton fabric prepared in Example 1 of the present invention to the contact and separation of oil (n-hexane) under water; Figure 4 The contact angle test of the modified cotton fabric prepared in Comparative Example 2 of the present invention on water under oil (n-hexane); Figure 5 The contact angle test of the modified cotton fabric prepared in Comparative Example 3 of the present invention to water under oil (n-hexane); Figure 6 This is a contact angle test of the modified cotton fabric prepared in Comparative Example 4 of the present invention to water under oil (n-hexane). DETAILED DESCRIPTION

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items. The "include" or "comprising" described in the present invention can also be replaced by the closed "for" or "consisting of...".

[0040] The present invention is 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 implement it, but the embodiments are not intended to limit the present invention. Example 1

[0041] This embodiment relates to the preparation of an underwater super oleophobic-under-oil super hydrophilic porous material, which specifically includes the following steps: (1) The cotton fabric was immersed in an ethanol solution containing 20 wt% of 3-mercaptopropyltriethoxysilane for 2 h, and then rinsed with ethanol three times to remove the free 3-mercaptopropyltriethoxysilane on the surface. The cotton fabric was then dried in an oven at 80 °C to obtain the 3-mercaptopropyltriethoxysilane treated cotton fabric.

[0042] (2) The hydrophilic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide, the crosslinking agent polyethylene glycol diacrylate and the photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone were added to the aqueous solution and stirred at room temperature for 20 min to obtain an oil-free superphilic solution with a solid content of 15%. The fabric modified with 3-mercaptopropyltriethoxysilane was then immersed in the above solution for 30 min and transferred to a UV curing box for irradiation. After the irradiation, the sample was immersed in deionized water for 2 h to remove the components that were not directly on the surface of the fabric, and the modified cotton fabric was prepared. Among them, the molar ratio of the hydrophilic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide to the crosslinking agent polyethylene glycol diacrylate was 5:1, the wavelength of the UV source was 365 nm, and the UV irradiation intensity was 50 W / cm 2 The irradiation time is 15 min.

[0043] Figure 1 The SEM image of the modified cotton fabric prepared in this example shows that a uniform and tightly bonded modified layer can be observed on the surface of the cotton fabric. The contact angle of the modified cotton fabric prepared in this example to water under oil and to oil under water were tested, and the results are as follows: Figure 2 , 3 As shown in the figure, water can quickly spread on the surface of modified cotton fabric in n-hexane, and the complete spreading time is only 1 s ( Figure 2 ), showing superhydrophilic properties under oil; in addition, Figure 3 It can be seen that the contact angle of the modified cotton fabric to n-hexane under water is greater than 150°, and the oil droplets will quickly detach from the surface after contacting the modified cotton fabric, showing underwater super oleophobic properties. It can be seen that the modified cotton fabric prepared in this example has underwater super oleophobic-oil super hydrophilic properties. Example 2

[0044] This embodiment relates to the preparation of an underwater superoleophobic-under-oil superhydrophilic porous material, and the only difference from Embodiment 1 is that the hydrophilic monomer in step (2) is 2-acrylamide-2-methylpropanesulfonic acid, and the other conditions are the same, and the corresponding modified cotton fabric is prepared.

[0045] The contact angle of the modified cotton fabric prepared in this embodiment to water under oil and the contact angle to oil under water were tested, and the results showed that in n-hexane, the complete spreading time of water was 3 s; the contact angle to n-hexane under water was greater than 150°, showing super oleophobicity under water and super hydrophilicity under oil. Example 3

[0046] This embodiment relates to the preparation of an underwater superoleophobic-under-oil superhydrophilic porous material, and the only difference from Embodiment 1 is that the hydrophilic monomer in step (2) is carboxybetaine methacrylate, and the other conditions are the same, and the corresponding modified cotton fabric is prepared.

[0047] The contact angle of the modified cotton fabric prepared in this embodiment to water under oil and the contact angle to oil under water were tested, and the results showed that in n-hexane, the complete spreading time of water was 3.5 s; the contact angle to n-hexane under water was greater than 150°, showing super oleophobicity under water and super hydrophilicity under oil. Example 4

[0048] This embodiment relates to the preparation of an underwater superoleophobic-under-oil superhydrophilic porous material, and the only difference from Embodiment 1 is that the hydrophilic monomer in step (2) is dimethylaminoethyl methacrylate, and the other conditions are the same, and the corresponding modified cotton fabric is prepared.

[0049] The contact angle of the modified cotton fabric prepared in this embodiment to water under oil and the contact angle to oil under water were tested, and the results showed that in n-hexane, the complete spreading time of water was 7 s; the contact angle to n-hexane under water was greater than 150°, showing super oleophobicity under water and super hydrophilicity under oil. Example 5

[0050] This embodiment relates to the preparation of an underwater superoleophobic-under-oil superhydrophilic porous material, and the only difference from Example 1 is that in step (2), the molar ratio of the hydrophilic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide to the cross-linking agent polyethylene glycol diacrylate is 1:1, and the other conditions are the same, and the corresponding modified cotton fabric is prepared.

[0051] The contact angle of the modified cotton fabric prepared in this embodiment to water under oil and the contact angle to oil under water were tested, and the results showed that in n-hexane, the complete spreading time of water was 21 s; the contact angle to n-hexane under water was greater than 150°, showing super oleophobicity under water and super hydrophilicity under oil. Example 6

[0052] This embodiment relates to the preparation of an underwater superoleophobic-under-oil superhydrophilic porous material, and the only difference from Example 1 is that in step (2), the molar ratio of the hydrophilic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide to the cross-linking agent polyethylene glycol diacrylate is 30:1, and the other conditions are the same, and the corresponding modified cotton fabric is prepared.

[0053] The contact angle of the modified cotton fabric prepared in this embodiment to water under oil and the contact angle to oil under water were tested, and the results showed that in n-hexane, the complete spreading time of water was 35 s; the contact angle to n-hexane under water was greater than 150°, showing super oleophobicity under water and super hydrophilicity under oil. Example 7

[0054] This embodiment relates to the preparation of an underwater superoleophobic-under-oil superhydrophilic porous material, and the only difference from Embodiment 1 is that the crosslinking agent in step (2) is N,N-methylenebisacrylamide, and the other conditions are the same, and the corresponding modified cotton fabric is prepared.

[0055] The contact angle of the modified cotton fabric prepared in this embodiment to water under oil and the contact angle to oil under water were tested, and the results showed that in n-hexane, the complete spreading time of water was 4 s; the contact angle to n-hexane under water was greater than 150°, showing super oleophobicity under water and super hydrophilicity under oil. Example 8

[0056] The present embodiment relates to the preparation of an underwater superoleophobic-under-oil superhydrophilic porous material, and the only difference from the embodiment 1 is that in step (2), the crosslinking agent is an acrylate-based cage-type polysilsesquioxane, the solvent is acetone, and the molar ratio of the hydrophilic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide to the crosslinking agent acrylate-based cage-type polysilsesquioxane is 50:1, and the other conditions are the same, and the corresponding modified cotton fabric is prepared.

[0057] The contact angle of the modified cotton fabric prepared in this embodiment to water under oil and the contact angle to oil under water were tested, and the results showed that in n-hexane, the complete spreading time of water was 9 s; the contact angle to n-hexane under water was greater than 150°, showing super oleophobicity under water and super hydrophilicity under oil. Example 9

[0058] This embodiment relates to the preparation of an underwater super-oleophobic-under-oil super-hydrophilic porous material, and the only difference from the embodiment 4 is that a thermal initiator is used in step (2) to initiate the crosslinking reaction, as follows: (1) The cotton fabric was immersed in an ethanol solution containing 20 wt% of 3-mercaptopropyltriethoxysilane for 2 h, and then rinsed with ethanol three times to remove the free 3-mercaptopropyltriethoxysilane on the surface. The cotton fabric was then dried in an oven at 80 °C to obtain the 3-mercaptopropyltriethoxysilane treated cotton fabric.

[0059] (2) Add hydrophilic monomer dimethylaminoethyl methacrylate, crosslinking agent polyethylene glycol diacrylate and thermal initiator azobisisobutyronitrile into the aqueous solution and stir at room temperature for 20 min to obtain an oil-soluble superphilic aqueous solution with a solid content of 8%. The molar ratio of hydrophilic monomer dimethylaminoethyl methacrylate to crosslinking agent polyethylene glycol diacrylate is 5:1. The fabric modified with 3-mercaptopropyltriethoxysilane is immersed in the above solution and heated to 80 °C and stirred for 1 h to obtain a modified cotton fabric.

[0060] The contact angle of the modified cotton fabric prepared in this embodiment to water under oil and the contact angle to oil under water were tested, and the results showed that in n-hexane, the complete spreading time of water was 10 s; the contact angle to n-hexane under water was greater than 150°, showing super oleophobicity under water and super hydrophilicity under oil. Comparative Example 1

[0061] This comparative example relates to the preparation of an underwater superoleophobic-under-oil superhydrophilic porous material, which is different from Example 4 only in that the fabric is not modified with siloxane, and the other conditions are the same, and the corresponding modified cotton fabric is prepared.

[0062] The contact angles of the modified cotton fabric prepared in this comparative example to water under oil and to oil under water were tested, and the results showed that in n-hexane, the complete spreading time of water was 13 s; the contact angle to n-hexane under water was greater than 150°, showing super oleophobicity under water and super hydrophilicity under oil. Comparative Example 2

[0063] This comparative example relates to the preparation of an underwater superoleophobic-under-oil superhydrophilic porous material, which differs from Example 4 only in that the hydrophilic monomer in step (2) is acrylamide, and the other conditions are the same, and the corresponding modified cotton fabric is prepared.

[0064] The contact angles of the modified cotton fabric prepared in this comparative example to water under oil and to oil under water were tested, and the results showed that in n-hexane, the contact angle of water was 152°; the contact angle to n-hexane under water was greater than 150°, showing super oleophobicity under water and super hydrophilicity under oil. Comparative Example 3

[0065] This comparative example relates to the preparation of an underwater superoleophobic-under-oil superhydrophilic porous material, which differs from Example 4 only in that the hydrophilic monomer in step (2) is methacrylic acid, and the other conditions are the same, and the corresponding modified cotton fabric is prepared.

[0066] The contact angles of the modified cotton fabric prepared in this comparative example to water under oil and to oil under water were tested, and the results showed that in n-hexane, the contact angle of water was 155°; the contact angle to n-hexane under water was greater than 150°, showing super oleophobicity under water and super hydrophilicity under oil. Comparative Example 4

[0067] This comparative example relates to the preparation of an underwater superoleophobic-under-oil superhydrophilic porous material, which differs from Example 1 only in that no crosslinking agent is included in step (2), and the other conditions are the same, thereby preparing a corresponding modified cotton fabric.

[0068] The contact angles of the modified cotton fabric prepared in this comparative example to water under oil and to oil under water were tested, and the results showed that in n-hexane, the contact angle of water was 140°; the contact angle to n-hexane under water was greater than 150°, showing super oleophobicity under water and super hydrophilicity under oil.

[0069] The contact angle test results of the modified cotton fabrics prepared in the above examples and comparative examples to water (under oil) and oil (under water) are shown in Table 1 below: Table 1

[0070] Application Example 1 The modified cotton fabrics prepared in Example 1 and Comparative Example 1 were named modified cotton fabrics 1 and 2, respectively. The modified cotton fabrics 1 and 2 were used to test the separation efficiency, separation flux and durability of the oil-water mixture. 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, and then the modified cotton fiber felts 1 and 2 were used to test the separation efficiency, separation flux and durability of the water-in-oil emulsion and the oil-in-water emulsion, respectively. The test process is as follows: Preparation of oil-water mixture: 50 g of water and 50 g of n-hexane were mixed to prepare an oil-water mixture.

[0071] 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, C 1 is the mass of the oil after separation, C 0 is the mass of oil before separation.

[0072] Preparation of water-in-oil emulsion: 0.2 g Span 80, 2 g water and 100 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.

[0073] Test method for separation efficiency of water-in-oil emulsion: The test instrument is a trace moisture tester (Zibo Zifen Instrument Co., Ltd.); 1 mL of the filtrate before filtration and the filtrate after filtration are taken, and the initial concentration of water in the emulsion before treatment and the residual concentration of water in the oil phase after filtration are measured. The water content is C 0 With C 1 (unit is ppm), and finally according to the formula , the separation efficiency is calculated.

[0074] 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.

[0075] Test method for separation efficiency of water-in-oil emulsion: The test instrument is an infrared oil meter (Qingdao Juchuang Environmental Protection Group Co., Ltd.); take 100 mL of the filtrate before filtration and the filtrate after filtration, inject the treated extract into a quartz cuvette, put it into the instrument sample pool, test the absorbance at 2930 cm⁻¹, and measure the initial concentration of oil in the emulsion before treatment and the residual concentration of oil in the water phase after filtration. The water content is C 0 With C 1 (unit: ppm), and finally according to , the separation efficiency is calculated.

[0076] The test method of separation flux is: the volume of permeate passing through a 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 membrane effective area in m 2 ; t is the running time, in h.

[0077] Durability test method: 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 corresponding separation efficiency after 10 cycles.

[0078] The above test results are shown in Table 2 below: Table 2

[0079] It can be seen from Table 2 that the first separation efficiency of the modified cotton fabric 1 prepared in Example 1 for the oil-water mixture is equivalent to that of the modified cotton fabric 2, but its separation flux for the oil-water mixture is greatly improved, and after 10 cycles, the separation efficiency of the modified cotton fabric 1 for the oil-water mixture can still reach 98.1%, while the surface coating of the modified cotton fabric 2 falls off after the cyclic separation operation, and during the 10th separation, both oil and water will pass through, thereby failing to achieve oil-water separation.

[0080] In addition, the cotton fiber felt was modified by the method in Example 1 and Comparative Example 1 to obtain the corresponding modified cotton fiber felts 1 and 2, and the first separation efficiency for oil-in-water emulsions was comparable, among which the modified cotton fiber felt 1 had a better first separation efficiency for water-in-oil emulsions. More importantly, compared with the modified cotton fiber felt 2, the modified cotton fiber felt 1 had a significantly higher separation flux for oil-in-water emulsions and water-in-oil emulsions, and could still maintain a high separation efficiency after 10 cycles, showing excellent durability. Application Example 2

[0081] Taking the modified cotton fabric prepared in Example 9 as an example, it is used for fabric dyeing and color fixation, and the specific operation is as follows: After heating and stirring the reaction in step (2) of Example 9, the solution was cooled to 30°C and the pH value of the solution was adjusted to 5-6. Then, the reactive dye RB19 was added, stirred evenly, and kept warm for 30 min. The temperature was then raised to 60°C at 2°C / min, and 10 g / L anhydrous Na 2 CO 3 , heat preservation and fixation for 60 min. After dyeing, the front and back sides of the fabric were repeatedly rinsed with distilled water, and the fabric sample was put into the soaping liquid for washing and drying to prepare the dyed modified cotton fabric. Among them, the dye RB19 was used in an amount of 2% (owf), the bath ratio was 20:1, and the soaping conditions were: bath ratio 20:1, concentration 2 g / L, temperature 95 ℃, and full soaping for 10 min.

[0082] For comparison, unmodified cotton fabrics were dyed without salt and conventionally.

[0083] Salt-free dyeing of unmodified cotton fabrics: adjust the pH value of the pre-prepared dye solution to 5-6, heat it to a predetermined temperature, dye the fabric, keep it warm for a predetermined time, then heat it to 60 °C at 2 °C / min, add 10 g / L anhydrous Na 2 CO 3 , heat preservation and color fixation for 60 minutes. After dyeing, the front and back of the fabric were repeatedly rinsed with distilled water, and then the fabric sample was put into the soaping liquid for washing and drying to prepare the dyed modified cotton fabric. Among them, the dye RB19 was used in an amount of 2% (owf), the bath ratio was 20:1 for dyeing, and the soaping conditions were: bath ratio 20:1, concentration 2 g / L, temperature 95 ℃, and full soaping for 10 minutes.

[0084] Traditional salt dyeing: Heat the prepared dye solution to 30 °C, dye the fabric, keep it warm for 15 min, add 60g NaCl, continue dyeing for 15 min, heat it to 60 °C at 2 °C / min, add 10 g / L anhydrous Na 2 CO 3 , heat fixation for 60 min. After dyeing, rinse the front and back of the fabric repeatedly with distilled water and put the fabric sample into the soaping solution. Among them, the dye RB19 dosage is 2% (owf), the bath ratio is 20:1, and the soaping conditions are: bath ratio 20:1, concentration 2 g, temperature 95 ℃, and full soaping for 10 min.

[0085] The test results of fabric dyeing treatment using different processes are as follows: the modified cotton fabric prepared in Example 9 is used for salt-free dyeing, and the dyeing rate of RB19 can reach 84.3%, the color fixation rate is 75.9%, the soap fastness is 4-5, the color fastness to dry friction is 4-5, and the color fastness to wet friction is 4. While the unmodified fabric is subjected to salt-free dyeing, the dyeing rate of RB19 is only 38.7%, the color fixation rate is 23.5%, the soap fastness is 3-4, the color fastness to dry friction is 4, and the color fastness to wet friction is 3. The dyeing rate of the unmodified cotton fabric subjected to traditional salt dyeing is 74.6%, the color fixation rate is 63.5%, the soap fastness is 4-5, the color fastness to dry friction is 4-5, and the color fastness to wet friction is 3-4. It can be seen that the dye uptake rate and fixation rate of salt-free dyeing of cotton fabrics modified by the present invention are significantly better than the dye uptake rate and fixation rate of salt-free / salt dyeing of unmodified fabrics, and the soap fastness, dry friction color fastness and wet friction color fastness are higher.

[0086] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for preparing an underwater superoleophobic-under-oil superhydrophilic porous material, characterized in that: The following steps are involved: S1, immersing the hydroxyl-containing porous substrate in a modifier solution to perform surface modification treatment to obtain a modified porous substrate; The modifier at least comprises a group A that can react with a hydroxyl group and a group B that can react with a carbon-carbon double bond; S2, immersing the modified porous substrate in a mixed solution comprising a hydrophilic monomer, a crosslinking agent and an initiator, and performing a crosslinking reaction to obtain the underwater superoleophobic-under-oil superhydrophilic porous material; when the initiator is a thermal initiator, the crosslinking reaction is performed under heating conditions; when the initiator is a photoinitiator, the crosslinking reaction is performed under ultraviolet light irradiation conditions; The hydrophilic monomer is a zwitterionic and / or strongly ionic hydrophilic monomer and contains at least one carbon-carbon double bond; the crosslinking agent contains at least two carbon-carbon double bonds.

2. The preparation method according to claim 1, characterized in that: In step S1, the porous substrate comprises cellulose fabric, non-manufactured cloth 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 siloxane containing mercapto group or carbon-carbon double bond.

4. The preparation method according to claim 1, characterized in that: In step S1, at least one of the following features is included: (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 surface modification treatment time is 0.2-24 h.

5. The preparation method according to claim 1, characterized in that: In step S2, the hydrophilic monomer is selected from one or more of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonatepropyl)ammonium hydroxide, carboxy betaine methacrylate, methacryloyloxyethyl phosphorylcholine, 2-acrylamido-2-methylpropanesulfonic acid, sulfopropyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, methacryloyloxyethyltrimethylammonium chloride, dimethyldiallylammonium chloride, acryloyloxyethyltrimethylammonium 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, polydipentaerythritol pentaacrylate, vinyl cage polysilsesquioxane and acrylate cage polysilsesquioxane; The thermal initiator is selected from one or more of dibenzoyl peroxide, dilauroyl 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-trimethylbenzoyldiphenylphosphine oxide, a,a,-dimethylbenzil ketal, benzophenone, 1-hydroxycyclohexylbenzophenone and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

6. The preparation method according to claim 1, characterized in that: In step S2, at least one of the following features is included: (1) The mixed solution is obtained by dissolving a hydrophilic monomer, a crosslinking agent and an 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 cross-linking agent is (1-300):1; (4) The ratio of the total mass of the hydrophilic monomer and the cross-linking agent to the mass of the initiator is (5-200): 1; (5) The heating conditions are as follows: the heating temperature is 40-120°C and the heating time is 10 min-240 min; (6) The ultraviolet light irradiation conditions are: the wavelength of the ultraviolet light is 200-500 nm, and the irradiation intensity is 20-150 W / cm 2 The irradiation time is 5 min-120 min.

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

8. Use of the underwater superoleophobic-under-oil superhydrophilic porous material according to claim 7 in oil-water separation materials.

9. Use of the underwater superoleophobic-under-oil superhydrophilic porous material according to claim 7 in materials for easy degreasing.

10. Use of the underwater superoleophobic-under-oil superhydrophilic porous material according to claim 7 in promoting dyeing and fixing of fabrics.

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