CN112759670A

CN112759670A - Mussel bionic functionalized hydrophilic polymer and hydrophilic polymer network modified super-hydrophilic net membrane as well as preparation method and application thereof

Info

Publication number: CN112759670A
Application number: CN202011497097.3A
Authority: CN
Inventors: 李琳; 戴彩丽; 徐忠正; 孙永鹏; 吴一宁; 赵光; 赵明伟
Original assignee: China University of Petroleum East China
Current assignee: China University of Petroleum East China
Priority date: 2020-12-17
Filing date: 2020-12-17
Publication date: 2021-05-07
Anticipated expiration: 2040-12-17
Also published as: CN112759670B

Abstract

The invention relates to the field of surface modification of high molecular functional materials and solid materials, and discloses a mussel bionic functionalized hydrophilic polymer, a hydrophilic polymer network modified super-hydrophilic net film, a preparation method and application thereof. The preparation method comprises the following steps: (1) in the presence of an initiator, 2- (bi) methacrylic acidContacting methylamino) ethyl ester, polyethanol methacrylate, acrylic acid pentafluorophenol ester, 4-cyano-4 (dodecyl sulfanyl thiocarbonyl) sulfanyl valeric acid and 1, 4-dioxane to obtain a product I; (2) contacting the product I, dichloromethane, dopamine hydrochloride and triethylamine, and then carrying out centrifugal separation to obtain a product II; (3) and contacting the product II, dichloromethane and methyl iodide to obtain the hydrophilic polymer. The separation flux of the hydrophilic polymer network modified super-hydrophilic net film of the invention is as high as 5641.1L/m^‑2·h^‑1The separation efficiency is as high as 99.98%.

Description

Mussel bionic functionalized hydrophilic polymer and hydrophilic polymer network modified super-hydrophilic net membrane as well as preparation method and application thereof

Technical Field

The invention relates to the field of surface modification of high molecular functional materials and solid materials, in particular to a mussel bionic functionalized hydrophilic polymer, a hydrophilic polymer network modified super-hydrophilic net film, a preparation method and application.

Background

In recent years, while paying attention to economic development, society increasingly focuses on environmental protection problems, frequent marine oil spill events and discharge of industrial oily sewage, and great threats are caused to ecological environment and human health. The development of an effective oil-water separation technology has important significance for protecting the ecological environment and saving limited water resources. The membrane separation technology based on the oil-water wettability difference becomes a research hotspot due to the characteristics of environmental protection, energy conservation, high separation efficiency, convenient operation and the like.

Super-hydrophilic/underwater super-oleophobic membranes (dewatering) are of great interest in the fields of wastewater treatment and oil-water separation due to their excellent anti-fouling properties. The current widely used commercial membrane material has better pore structure and mechanical strength, but most of the membrane material presents intrinsic hydrophobicity, so that a simple, mild, environment-friendly and universal method for modifying various hydrophobic membranes into super-hydrophilic/underwater super-oleophobic membranes is urgently needed. In previous researches, the construction of a super-hydrophilic membrane is mainly realized by combining a hydrophilic polymer and nanoparticles, and the main oil-water separation mechanism of the super-hydrophilic membrane is a super-hydrophilic surface consisting of the hydrophilic polymer, so that when the super-hydrophilic surface is contacted with water, a hydration layer is formed on each membrane to repel and block oil.

CN101518695A discloses an oil-water separation net film with super-hydrophobic and super-oleophilic functions and a preparation method thereof, wherein the oil-water separation net film is formed by covering a thin layer of polysiloxane-bisphenol A copolymer cured film on the surface of a 100-400-mesh fabric net, but the oil-water separation net film is suitable for oil-water mixture separation and does not have the separation capability of oil-water emulsion.

CN104548667B discloses a net membrane for oil-water emulsion separation and a preparation method thereof, which is a composite net membrane formed by loading a metal oxide layer with a micro-nano composite structure on the meshes and the net wires of a metal net, wherein the metal oxide layer with the micro-nano composite structure is formed by nano zinc oxide and nano cobalt oxide clusters. However, the metal mesh has a pore diameter of 1 to 100 μm, so that the metal mesh has a poor effect of separating oil and water emulsion droplets of a nanometer level, and the surface structure of the metal mesh is easily damaged in certain specific environments (strong acid and strong base). The net film modified by inorganic nano materials and inorganic non-metallic materials is used, and the fine structure of the nano rods is destroyed and falls off into liquid in the oil-water separation process, so that the material waste and the water quality pollution are caused.

CN107596735A discloses a preparation device and a method of a super-amphiphobic self-cleaning oil-water separation material, wherein titanium dioxide nano-rods grow on the surface of a porous metal substrate. The substrate is modified with a polymer.

CN107441961A discloses a preparation method and application of a super-hydrophilic PVDF oil-water emulsion separation membrane, wherein the separation membrane contains end-sulfhydryl hyperbranched polyacrylamide, dopamine is subjected to self-polymerization deposition on the surface of the PVDF membrane to form a polydopamine layer, secondary functionalization modification is performed by utilizing dopamine adhesion, and the end-sulfhydryl hyperbranched polyacrylamide is coated on membrane pores and the surface of the membrane, so that the PVDF membrane has super-hydrophilic/underwater super-oleophobic and pollution-resistant properties, and the PVDF membrane for oil-water emulsion separation is provided.

Therefore, a membrane separation technology which has good separation effect on oil-water mixed liquid/emulsion, long continuous service time and simple and convenient modification method is needed to be found.

Disclosure of Invention

The invention aims to overcome the defects of poor separation effect, short service time and complex modification method of oil-water mixed liquid/emulsion in the prior art, and provides a mussel bionic functionalized hydrophilic polymer and hydrophilic polymer network modified super-hydrophilic net membrane as well as a preparation method and application thereof, wherein the separation flux of the hydrophilic polymer network modified super-hydrophilic net membrane is as high as 5641.1L/m^-2·h^-1The separation efficiency is as high as 99.98%, and the method has excellent pollution resistance and reusability.

In order to achieve the above object, a first aspect of the present invention provides a preparation method of a mussel biomimetic functionalized hydrophilic polymer, wherein the preparation method comprises:

(1) under the condition of the existence of an initiator, 2- (dimethylamino) ethyl methacrylate, polyethanol methacrylate, pentafluorophenol acrylate, 4-cyano-4 (dodecyl sulfanyl thiocarbonyl) sulfanyl pentanoic acid and 1, 4-dioxane are contacted to be heated and concentrated to obtain a product I;

(2) under the condition of oil bath, the product I, dichloromethane, dopamine hydrochloride and triethylamine are contacted and then are subjected to centrifugal separation to obtain a product II;

(3) and under the protection of nitrogen, contacting the product II, dichloromethane and methyl iodide to obtain the hydrophilic polymer.

In a second aspect, the invention provides a mussel bionic functionalized hydrophilic polymer containing a quaternary amine group, a polyethylene glycol group and a mussel bionic catechol group, which is prepared by the preparation method.

The third aspect of the invention provides a preparation method of a hydrophilic polymer network modified super-hydrophilic net film, wherein the preparation method comprises the following steps:

firstly, carrying out first contact on the mussel bionic functionalized hydrophilic polymer and a buffer solution to obtain a polymer solution;

(II) dipping the basal omentum in a trihydroxymethyl aminomethane buffer solution, and carrying out second contact on the obtained mixture and dopamine hydrochloride to obtain a polydopamine modified omentum;

and (III) dipping the net membrane modified by the polydopamine into the polymer solution to obtain the hydrophilic polymer network modified super-hydrophilic net membrane.

The invention provides a hydrophilic polymer network modified super-hydrophilic net film prepared by the preparation method.

In a fifth aspect the invention provides the use of a hydrophilic polymer network modified superhydrophilic web as described above in an oil-in-water emulsion.

Through the technical scheme, the technical scheme of the invention has the following advantages:

(1) the hydrophilic polymer synthesized in the invention selects the raw materials of the reaction of the polyethanol methacrylate, the methacrylic acid-2- (dimethylamino) ethyl ester and the dopamine hydrochloride, and the catechol functional hydrophilic copolymer simultaneously containing hydrophilic quaternary amine groups, polyethylene glycol chains and mussel bionic catechol groups is synthesized after RAFT polymerization and methyl iodide methylation treatment.

(2) The hydrophilic polymer network modified super-hydrophilic net film prepared by the invention is formed into a multi-stage micro-nano rough structure and a hydrophilic polymer network on the surface of a substrate net film through the treatment of polydopamine and the subsequent secondary modification of a hydrophilic polymer coating.

(3) The hydrophilic polymer network modified super-hydrophilic net membrane prepared by the invention shows good performance in the aspect of separating immiscible oil-in-water emulsion, and the separation flux is as high as 5641.1 L.m^-2·h^-1Efficiency of separationUp to 99.98%, and has excellent contamination resistance and reusability.

(4) The method for modifying the super-hydrophilic net film by the hydrophilic polymer network is simple and universal, can be expanded to various base materials and materials for practical application, and has huge application potential in the aspects of oily wastewater treatment, water resource recycling and the like.

(5) When the hydrophilic polymer network modified super-hydrophilic net film prepared by the invention is applied to an oil-in-water emulsion, hydrophilic quaternary amine groups and polyethylene glycol chains contained in the hydrophilic polymer can attract water shells in oil-in-water emulsion droplets, so that demulsification is caused, and micro oil droplets are continuously coagulated and then blocked by a thin water film formed by the hydrophilic polymer network.

Drawings

FIG. 1 is a schematic diagram of the synthetic route for the hydrophilic polymer of the present invention;

FIG. 2 is a schematic structural view of a hydrophilic polymer network modified superhydrophilic mesh membrane of the present invention;

fig. 3 (a), (b), and (c) are atomic force microscope two-dimensional imaging pictures of the first base mesh film prepared in step (2), the second base mesh film prepared in step (3), and the third base mesh film prepared in step (4) of example 1, respectively; (e) (f) and (g) are atomic force microscope three-dimensional imaging pictures of the first base mesh film prepared in the step (2), the second base mesh film prepared in the step (3) and the third base mesh film prepared in the step (4) in example 1, respectively;

fig. 4 is a scanning electron microscope and a corresponding energy dispersive spectroscopy image of a third substrate mesh film prepared in step (4) of example 1 of the present invention, wherein C, N, O and F elements are selectively characterized on the surface of the substrate mesh film (polyvinylidene fluoride);

FIG. 5 is an infrared spectrum of the omentum at various stages of treatment according to example 1 of the present invention;

FIG. 6 is an X-ray photoelectron spectrum of a web at different stages of processing according to example 1 of the present invention, wherein 1, 2, and 3 in FIG. 6(a) are high-fraction C1s spectra of a first substrate web, a second substrate web, and a third substrate web, respectively;

FIG. 7 is a graph showing the change in contact angle with time of water drops in the air of the hydrophilic polymer network-modified superhydrophilic web prepared in step (4) of example 1 of the present invention;

FIG. 8 is the contact angle of the hydrophilic polymer network modified super-hydrophilic mesh membrane prepared in step (4) of example 1 of the present invention under water for different kinds of oil drops;

FIG. 9 shows the separation efficiency (FIG. 9a) and flux (FIG. 9b) of the modified superhydrophilic omentum prepared in example 1 of the present invention applied to separate different oil-water mixtures;

FIG. 10 is the separation efficiency (FIG. 10a) and throughput (FIG. 10b) of the modified superhydrophilic omentum made in example 1 of the present invention applied to separate different oil-in-water emulsions;

FIG. 11 is a schematic view of an oil-water emulsion separator according to the present invention; before oil-water emulsion separation (figure b)₁FIG. c₁FIG. d₁) And after separation (FIG. b)₂FIG. c₂FIG. d₂) High power optical microscope pictures of (a); wherein the diagram b₁FIG. b₂Corresponding to an n-hexane/water/SDS oil-in-water emulsion, panel c₁FIG. c₂Corresponding to chloroform/water/SDS oil-in-water emulsion, panel d₁FIG. d₂Corresponding to gasoline/water/SDS oil-in-water emulsion.

Description of the reference numerals

1-first base web (polyvinylidene fluoride) prepared in step (2) of example 1;

example 1 second basal omentum prepared in step (3) (after polydopamine modification);

3-third base cap membrane (after hydrophilic polymer/polydopamine modification) prepared in step (4) of example 1.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In order to achieve the purpose of the invention, the first aspect of the invention provides a preparation method of a mussel biomimetic functionalized hydrophilic polymer, wherein the preparation method comprises the following steps:

The inventors of the present invention have surprisingly found that: 4-cyano-4 (dodecyl sulfanyl thiocarbonyl) sulfanyl valeric acid is adopted as RAFT reagent to carry out active controllable polymerization, and the RAFT reagent can effectively control the polymerization reaction rate, so that reaction monomers are relatively and uniformly distributed on a polymer main chain, the conversion rate of the monomers can be further improved, the molecular weight distribution width of the polymer is reduced, and the functionalized hydrophilic polymer simultaneously containing hydrophilic groups (quaternary ammonium salt groups and polyethylene glycol groups) and mussel bionic catechol (adhesion) groups is prepared.

According to the invention, in the step (1), 2- (dimethylamino) ethyl methacrylate, polyethanol methacrylate, pentafluorophenol acrylate, 4-cyano-4 (dodecyl sulfanyl thiocarbonyl) sulfanyl pentanoic acid and 1, 4-dioxane are contacted to obtain a first reaction system; wherein the millimolar (unit, mmol) ratio of 2- (dimethylamino) ethyl methacrylate, polyethanol methacrylate, pentafluorophenol acrylate, 4-cyano-4 (dodecylsulfanylthiocarbonyl) sulfanylpentanoic acid, and the amount of the initiator is (5-20) relative to 10-30mL of 1, 4-dioxane: (8-16): (5-20): (0.5-2): (0.125-0.5); preferably (8-15): (10-16): (9-18): (0.75-1.7): (0.1875-0.425).

According to the invention, the initiator is azobisisobutyronitrile.

According to the invention, the first reaction system is transferred into an oil bath for heating treatment to obtain a second reaction system; wherein the heating conditions include: the temperature is 65-80 ℃, and the time is 2-5 h; preferably, the temperature is 70-75 ℃, and the time is 3-4 h; more preferably, the temperature is 72 ℃ and the time is 3-4 h.

According to the invention, after the second reaction system is concentrated, the second reaction system is slowly dripped into petroleum ether (or n-hexane), and the product I (light yellow oily liquid drops) is separated out.

According to the invention, in the step (2), dissolving the obtained product I in dichloromethane, adding dopamine hydrochloride and triethylamine, and stirring under the condition of oil bath to obtain a third reaction system; wherein the concentration conditions include: the temperature is 55-65 ℃, preferably 60-65 ℃; the oil bath conditions included: the temperature is 35-40 ℃ and the time is 12-24 h. In the present invention, the concentration may be rotary evaporation concentration.

According to the invention, the amount of dopamine hydrochloride and triethylamine is used in a millimolar (unit, mmol) ratio, relative to 10-30mL of 1, 4-dioxane, of (5-25): (10-50), preferably (10-20): (10-40).

According to the present invention, in step (2), the amount of methylene chloride to be used is (10-35) mL, preferably (15-30) mL, relative to 10-30mL of 1, 4-dioxane.

According to the invention, preferably, the mass ratio of the product I, dopamine hydrochloride, triethylamine and dichloromethane is (3.8-8.8): (1.9-3.8): (1-3.6): (20-40).

According to the invention, in the step (3), the third reaction system is poured into a centrifuge tube for centrifugal separation, the supernatant is taken and slowly dropped into ether, and the product II (white floccule) is separated out. Standing until floccule precipitates completely, pouring off supernatant, and drying floccule for later use (white fluffy state changes into yellow sticky state). Dissolving the dried product II in dichloromethane, introducing nitrogen, adding methyl iodide, and reacting at room temperature to obtain a fourth reaction system; and adding excessive dichloromethane into the fourth reaction system, centrifuging, taking the lower-layer precipitate, and drying in vacuum to obtain the final product, namely the hydrophilic polymer.

According to the invention, in step (3), the amount of dichloromethane is 10 to 35mL, preferably 15 to 30mL, and the amount of methyl iodide is 10 to 35mmol, preferably 15 to 30mmol, relative to 10 to 30mL of 1, 4-dioxane.

According to a preferred embodiment of the present invention, the method for preparing the hydrophilic polymer comprises:

(1') dissolving 2- (dimethylamino) ethyl methacrylate, polyethanol methacrylate, pentafluorophenol acrylate and 4-cyano-4 (dodecyl sulfanyl thiocarbonyl) sulfanyl pentanoic acid in 1, 4-dioxane in a round-bottom flask; introducing nitrogen and stirring for 20-40 min; adding an initiator azobisisobutyronitrile, introducing nitrogen, and stirring for 10-20min to obtain a first reaction system, wherein the millimole (unit, mmol) ratio of the dosages of 2- (dimethylamino) ethyl methacrylate, polyethanol methacrylate, pentafluorophenol acrylate, 4-cyano-4 (dodecylsulfanylthiocarbonyl) sulfanylpentanoic acid and azobisisobutyronitrile is (8-15) relative to 10-30mL of 1, 4-dioxane: (10-16): (9-18): (0.75-1.7): (0.1875-0.425);

(2') transferring the first reaction system to an oil bath for heating, and stirring for 3-4h at 72 ℃ to obtain a second reaction system;

(3') after the second reaction system is concentrated at 60 ℃, the second reaction system is slowly dripped into petroleum ether (or normal hexane), and a product I (light yellow oily liquid drops) is separated out. Dissolving the obtained product I in dichloromethane, adding dopamine hydrochloride and triethylamine, and stirring for 12-24h under the condition of 36 ℃ oil bath to obtain a third reaction system, wherein the millimole (unit, mmol) ratio of the amounts of the dopamine hydrochloride and the triethylamine is (10-20) relative to 10-30mL of 1, 4-dioxane: (10-40), wherein the dosage of the dichloromethane is (15-30) mL;

(4') pouring the third reaction system into a centrifuge tube, centrifuging for 5min at the rotation speed of 8000rpm, taking supernatant, and slowly dropping the supernatant into ether to separate out a product II (white floccule). Standing until floccule precipitates completely, pouring off supernatant, and drying floccule for later use (white fluffy state changes into yellow sticky state). Dissolving the dried product II in dichloromethane, introducing nitrogen for 15min, adding methyl iodide, reacting at room temperature for 4h to obtain a fourth reaction system, wherein the amount of dichloromethane is 15-30mL and the amount of methyl iodide is 15-30mmol relative to 10-30mL of 1, 4-dioxane;

(5') adding excessive dichloromethane into the fourth reaction system, centrifuging, taking the lower-layer precipitate, and drying in vacuum to obtain the final product, namely the hydrophilic polymer.

(II) dipping the basal omentum in a tris buffer solution, and carrying out second contact on the obtained mixture and dopamine hydrochloride to obtain a dopamine-modified omentum;

and (III) dipping the dopamine modified net membrane into the polymer solution to obtain the hydrophilic polymer network modified super-hydrophilic net membrane.

The inventors of the present invention have surprisingly found that: according to the invention, a poly-dopamine layer is constructed on the surface of the base membrane by adopting a dip coating method, a micro-nano rough structure is formed on the surface of the membrane, and meanwhile, abundant reaction sites are provided for further polymer grafting. The synthesized catechol-functionalized hydrophilic polymer can react with a polydopamine layer through various interactions to form a hydrophilic polymer network, and finally the hydrophilic polymer network modified super-hydrophilic net membrane can be obtained.

According to the invention, in step (one), the buffer solution is acetic acid/sodium acetate at a pH of 5-5.5, preferably at a pH of 5.

According to the present invention, in the step (one), the amount of the hydrophilic polymer is 5 to 20mg with respect to 1mL of the buffer solution.

According to the invention, in the step (two), the basement membrane is a polymer microfiltration membrane; preferably, the base web is selected from one or more of polytetrafluoroethylene, polypropylene and polyvinylidene fluoride.

According to the invention, the average pore diameter of the substrate mesh film is 0.2-0.5 μm, and the diameter of the substrate mesh film is 40-50 mm.

According to the present invention, in the step (two), it is preferable that the base web is coated with a coating solution having a volume ratio of 1: 1, ultrasonically cleaning for 30min by using a mixed solution of deionized water and ethanol, and drying by using nitrogen to obtain a first substrate net film.

According to the invention, in the step (two), preferably, the first substrate omentum is soaked in tris buffer solution, dopamine hydrochloride is added, the mixture is stirred and reacted, the omentum is taken out and washed by deionized water, and the nitrogen is used for drying, so that the dopamine-modified omentum, namely the second substrate omentum, is obtained.

The buffer solution of tris (hydroxymethyl) aminomethane has a mass concentration of 5-10mg/mL and a pH of 8.5-9, preferably a pH of 8.5.

According to the present invention, the amount of dopamine hydrochloride is 0.2 to 0.4g, preferably 0.2g, relative to 100mL of the tris buffer.

According to the invention, the conditions of the second contact comprise: the conditions of the third contacting include: under the condition of magnetic stirring, the temperature is 20-25 ℃, and the time is 24-48 h;

according to the invention, in the step (three), the second substrate net film is soaked in the polymer solution to obtain a third substrate net film, the third substrate net film is taken out and then is cleaned by deionized water, and the third substrate net film is dried by nitrogen gas, so that the hydrophilic polymer network modified super-hydrophilic net film is obtained.

According to the invention, the impregnation conditions include: stirring without magnetic force at 20-25 deg.C for 4-6 h.

According to the invention, the hydrophilic polymer network modified super-hydrophilic net membrane is a hydrophilic polymer network formed by interaction of a polydopamine coating and a hydrophilic polymer containing quaternary amine groups, polyethylene glycol groups and mussel bionic catechol groups on a substrate net membrane.

According to the invention, the average pore diameter of the hydrophilic polymer network modified super-hydrophilic net membrane is 0.2-0.5 μm, and the diameter of the hydrophilic polymer network modified super-hydrophilic net membrane is 40-50 mm.

In a fifth aspect the invention provides a use of a hydrophilic polymer network modified superhydrophilic web as described above in the separation of oil-in-water emulsions.

According to the invention, the oil-in-water emulsion contains an oil phase and a water phase; wherein the oil phase is selected from one or more of n-hexane, petroleum ether, toluene, dichloromethane, chloroform, gasoline and diesel oil, and the water phase is water; preferably, the volume ratio of the used amount of the oil phase to the used amount of the water phase is (1-3): (97-99); in addition, in the present invention, the oil phase is dispersed in the water phase, and the dispersion is carried out using a homogenizer at a dispersion rate of 10000-.

According to the invention, the oil-in-water emulsion also contains a surfactant; preferably, the surfactant is sodium lauryl sulfate and is used in an amount of 0.1-0.3mg per 1mL of the oil-in-water emulsion.

The present invention will be described in detail below by way of examples.

In the following examples and comparative examples:

the surface elemental composition of each modified stage film was measured by x-ray photoelectron spectroscopy (Thermo scientific Escalab 250Xi) and energy dispersive x-ray spectroscopy (FEI QUANTA FEG 250); the surface morphology of the membrane at each modification stage was measured by atomic force microscopy (Bruker MultiMode8) and field emission scanning electron microscopy (Hitachi S-4700); the macroscopic wettability of the modified film was measured by a contact angle measuring instrument (JC 2000D); optical microscopy was performed before and after emulsion separation and measured by a photomicrograph system (Leica DMi 8C); the oil content in the filtrate was calibrated by UV spectrophotometry and determined using a UV spectrophotometer (METTLER TOLEDO UV 5).

Poly (ethylene glycol) methyl methacrylate (PEGMA, available from Adamas-beta), 2- (dimethylamino) ethyl methacrylate (DMAEMA, available from Adamas-beta), pentafluorophenyl acrylate (PFPA, available from Adamas-beta) and 4-cyano-4 (dodecylsulfanylthiocarbonyl) sulfanylpentanoic acid (RAFT, available from knooke) were used as starting materials for polymer synthesis. 2, 2' -azobis (2-methylpropionitrile) (AIBN, from Allatin) was used as a catalyst for the reaction. Dopamine hydrochloride (DOPA, from Aladdin for short), iodomethane (from Aladdin) triethylamine (from Shanghai nationality medicine), dioxane (from Shanghai nationality medicine) and dichloromethane (from Shanghai nationality medicine) were not further purified during the copolymer synthesis.

Acetic acid (from shanghai drug) and sodium hydroxide (from shanghai drug) were used to prepare NaOAc/AcOH buffer solutions; tris (hydroxymethyl) aminomethane (from Adamas-beta) and hydrochloric acid (from Shanghai nationality) were used to prepare Tris buffered solutions.

Deionized water (16.3 M.OMEGA.cm at 298K) was prepared as an aqueous phase using a laboratory ultrapure water meter (Ulupure) with n-hexane (from Shanghai nationality), toluene (from Shanghai nationality), chloroform (from Shanghai nationality), and gasoline (from China petrochemical group) as oil phases.

Petroleum ether (60-90 ℃, Shanghai medicine) is subjected to dearomatization treatment (lambda is 225nm, and T is more than 80%) and then is calibrated by an ultraviolet spectrophotometer method.

Preparation example 1

This preparation example is intended to illustrate the hydrophilic polymer obtained by the preparation process of the present invention.

Following the synthetic route for hydrophilic polymers shown in FIG. 1:

in the first step, 2- (dimethylamino) ethyl methacrylate (10mmol,1.57g), polyethanol methacrylate (10mmol,4.75g), pentafluorophenol acrylate (10mmol,2.38g), 4-cyano-4 (dodecylsulfanylthiocarbonyl) sulfanylpentanoic acid (1mmol,0.403g) were dissolved in 17mL1, 4-dioxane in a 50mL round bottom flask; introducing nitrogen and stirring for 20 min; adding an initiator of azobisisobutyronitrile (0.25mmol,0.041g), introducing nitrogen and stirring for 10min to obtain a first reaction system; transferring the first reaction system to an oil bath for heating, and stirring for 4 hours at 72 ℃ to obtain a second reaction system; after the obtained second reaction system is subjected to rotary evaporation and concentration at 60 ℃, the second reaction system is slowly dripped into petroleum ether (or normal hexane), and a product I (light yellow oily liquid drop) is separated out.

Secondly, dissolving the obtained product I in 20mL of dichloromethane, adding dopamine hydrochloride (15mmol,2.845g) and triethylamine (30mmol,4.16mL), and stirring for 12h under the condition of 36 ℃ oil bath to obtain a third reaction system; and pouring the third reaction system into a centrifuge tube, centrifuging for 5min at the rotation speed of 8000rpm, taking supernate, and slowly dripping into diethyl ether to separate out a product II (white floccule). Standing until floccule precipitates completely, pouring off supernatant, and drying floccule for later use (white fluffy state changes into yellow sticky state).

And step three, dissolving the dried product II in 20mL of dichloromethane, introducing nitrogen for 15min, adding iodomethane (20mmol,2.84g), and reacting at room temperature for 4h to obtain a fourth reaction system. And adding excessive dichloromethane into the fourth reaction system, centrifuging, taking the lower-layer precipitate, and vacuum drying to obtain a final product, namely the catechol-functionalized hydrophilic polymer Z1 simultaneously containing hydrophilic quaternary amine groups, polyethylene glycol groups and mussel bionic catechol groups.

Preparation example 2

Following the synthetic route for hydrophilic polymers shown in FIG. 1:

in the first step, 2- (dimethylamino) ethyl methacrylate (8mmol,1.256g), polyethanol methacrylate (16mmol,3.8g), pentafluorophenol acrylate (9mmol,2.147g), 4-cyano-4 (dodecylsulfanylthiocarbonyl) sulfanylpentanoic acid (0.75mmol,0.3g) were dissolved in 16mL of 1, 4-dioxane in a 50mL round bottom flask; introducing nitrogen and stirring for 20 min; adding an initiator azobisisobutyronitrile (0.1875mmol,0.018g), introducing nitrogen, and stirring for 10min to obtain a first reaction system; and transferring the first reaction system to an oil bath for heating, and stirring for 4 hours at 72 ℃ to obtain a second reaction system. After the obtained second reaction system is subjected to rotary evaporation and concentration at 60 ℃, the second reaction system is slowly dripped into petroleum ether (or normal hexane), and a product I (light yellow oily liquid drop) is separated out.

Secondly, dissolving the obtained product I in 15mL of dichloromethane, adding dopamine hydrochloride (10mmol,1.9g) and triethylamine (10mmol,1.38mL), and stirring for 12h under the condition of 36 ℃ oil bath to obtain a third reaction system; and pouring the third reaction system into a centrifuge tube, centrifuging for 5min at the rotation speed of 8000rpm, taking supernate, and slowly dripping into diethyl ether to separate out a product II (white floccule). Standing until floccule precipitates completely, pouring off supernatant, and drying floccule for later use (white fluffy state changes into yellow sticky state).

And step three, dissolving the dried product II in 15mL of dichloromethane, introducing nitrogen for 15min, adding iodomethane (15mmol,2.13g), and reacting at room temperature for 4h to obtain a fourth reaction system. And adding excessive dichloromethane into the fourth reaction system, centrifuging, taking the lower-layer precipitate, and vacuum drying to obtain a final product, namely the catechol-functionalized hydrophilic polymer Z2 simultaneously containing hydrophilic quaternary amine groups, polyethylene glycol and mussel bionic catechol groups.

Preparation example 3

Following the synthetic route for hydrophilic polymers shown in FIG. 1:

in the first step, 2- (dimethylamino) ethyl methacrylate (15mmol,2.355g), polyethanol methacrylate (16mmol, 7.6g), pentafluorophenol acrylate (18mmol,4.284g), 4-cyano-4 (dodecylsulfanylthiocarbonyl) sulfanylpentanoic acid (1.7mmol,0.685g) were dissolved in 30mL of 1, 4-dioxane in a 50mL round bottom flask; introducing nitrogen and stirring for 20 min; adding an initiator azobisisobutyronitrile (0.425mmol,0.069g), introducing nitrogen and stirring for 10min to obtain a first reaction system; and transferring the first reaction system to an oil bath for heating, and stirring for 4 hours at 72 ℃ to obtain a second reaction system. After the obtained second reaction system is subjected to rotary evaporation and concentration at 60 ℃, the second reaction system is slowly dripped into petroleum ether (or normal hexane), and a product I (light yellow oily liquid drop) is separated out.

Secondly, dissolving the obtained product I in 30mL of dichloromethane, adding dopamine hydrochloride (20mmol,3.793g) and triethylamine (40mmol,4.85mL), and stirring for 12h under the condition of 36 ℃ oil bath to obtain a third reaction system; and pouring the third reaction system into a centrifuge tube, centrifuging for 5min at the rotation speed of 8000rpm, taking supernate, and slowly dripping into diethyl ether to separate out a product II (white floccule). Standing until floccule precipitates completely, pouring off supernatant, and drying floccule for later use (white fluffy state changes into yellow sticky state).

And step three, dissolving the dried product II in 30mL of dichloromethane, introducing nitrogen for 15min, adding iodomethane (30mmol,4.26g), and reacting at room temperature for 4h to obtain a fourth reaction system. And adding excessive dichloromethane into the fourth reaction system, centrifuging, taking the lower-layer precipitate, and vacuum drying to obtain a final product, namely the catechol-functionalized hydrophilic polymer Z3 simultaneously containing hydrophilic quaternary amine groups, polyethylene glycol and mussel bionic catechol groups.

Preparation example 4

Following the synthetic route for hydrophilic polymers shown in FIG. 1:

in the first step, 2- (dimethylamino) ethyl methacrylate (5mmol,0.785g), polyethanol methacrylate (8mmol,1.9g), pentafluorophenol acrylate (5mmol,1.19g), 4-cyano-4 (dodecylsulfanylthiocarbonyl) sulfanylpentanoic acid (0.5mmol,0.202g) were dissolved in 10mL1, 4-dioxane in a 50mL round bottom flask; introducing nitrogen and stirring for 20 min; adding an initiator azobisisobutyronitrile (0.125mmol,0.021g), introducing nitrogen and stirring for 10min to obtain a first reaction system; and transferring the first reaction system to an oil bath for heating, and stirring for 4 hours at 72 ℃ to obtain a second reaction system. After the obtained second reaction system is subjected to rotary evaporation and concentration at 60 ℃, the second reaction system is slowly dripped into petroleum ether (or normal hexane), and a product I (light yellow oily liquid drop) is separated out.

Secondly, dissolving the obtained product I in 10mL of dichloromethane, adding dopamine hydrochloride (5mmol,0.95g) and triethylamine (30mmol,4.16mL), and stirring for 12h under the condition of 36 ℃ oil bath to obtain a third reaction system; and pouring the third reaction system into a centrifuge tube, centrifuging for 5min at the rotation speed of 8000rpm, taking supernate, and slowly dripping into diethyl ether to separate out a product II (white floccule). Standing until floccule precipitates completely, pouring off supernatant, and drying floccule for later use (white fluffy state changes into yellow sticky state).

And step three, dissolving the dried product II in 10mL of dichloromethane, introducing nitrogen for 15min, adding iodomethane (10mmol,1.42g), and reacting at room temperature for 4h to obtain a fourth reaction system. And adding excessive dichloromethane into the fourth reaction system, centrifuging, taking the lower-layer precipitate, and vacuum drying to obtain a final product, namely the catechol-functionalized hydrophilic polymer Z4 simultaneously containing hydrophilic quaternary amine groups, polyethylene glycol and mussel bionic catechol groups.

Preparation example 5

Following the synthetic route for hydrophilic polymers shown in FIG. 1:

in the first step, 2- (dimethylamino) ethyl methacrylate (20mmol,3.14g), polyethanol methacrylate (10mmol,4.75g), pentafluorophenol acrylate (20mmol,4.76g), 4-cyano-4 (dodecylsulfanylthiocarbonyl) sulfanylpentanoic acid (2mmol,0.806g) were dissolved in 30mL1, 4-dioxane in a 50mL round bottom flask; introducing nitrogen and stirring for 20 min; initiator azobisisobutyronitrile (0.5mmol,0.082g) is added, nitrogen is introduced and stirring is carried out for 10min, thus obtaining the first reaction system. And transferring the first reaction system to an oil bath for heating, and stirring for 4 hours at 72 ℃ to obtain a second reaction system. After the obtained second reaction system is subjected to rotary evaporation and concentration at 60 ℃, the second reaction system is slowly dripped into petroleum ether (or normal hexane), and a product I (light yellow oily liquid drop) is separated out.

Secondly, dissolving the obtained product I in 35mL of dichloromethane, adding dopamine hydrochloride (25mmol,4.74g) and triethylamine (50mmol, 6.06mL), and stirring for 12h under the condition of 36 ℃ oil bath to obtain a third reaction system; and pouring the third reaction system into a centrifuge tube, centrifuging for 5min at the rotation speed of 8000rpm, taking supernate, and slowly dripping into diethyl ether to separate out a product II (white floccule). Standing until floccule precipitates completely, pouring off supernatant, and drying floccule for later use (white fluffy state changes into yellow sticky state).

And step three, dissolving the dried product II in 35mL of dichloromethane, introducing nitrogen for 15min, adding iodomethane (35mmol,4.97g), and reacting at room temperature for 4h to obtain a fourth reaction system. And adding excessive dichloromethane into the fourth reaction system, centrifuging, taking the lower-layer precipitate, and vacuum drying to obtain a final product, namely the catechol-functionalized hydrophilic polymer Z5 simultaneously containing hydrophilic quaternary amine groups, polyethylene glycol and mussel bionic catechol groups.

Preparation example 6

A hydrophilic polymer was prepared in the same manner as in preparation example 1, except that:

in the first step, the amount of 2- (dimethylamino) ethyl methacrylate, 5mmol of polyethanol methacrylate, 5mmol of pentafluorophenol acrylate and 2mmol of 4-cyano-4 (dodecylsulfanylthiocarbonyl) sulfanylpentanoic acid were used, based on 17mL of 1, 4-dioxane.

In the second step, the dosage of dichloromethane is 20mL, the dosage of dopamine hydrochloride is 7.5mmol, and the dosage of triethylamine is 15 mmol.

In the third step, the dried product II was dissolved in 20mL of methylene chloride, and after introducing nitrogen, 10mmol of methyl iodide was added.

As a result, a hydrophilic polymer Z6 was produced.

Preparation example 7

in the first step, the amount of 2- (dimethylamino) ethyl methacrylate was 20mmol, the amount of polyethanol methacrylate was 20mmol, the amount of pentafluorophenol acrylate was 20mmol, and the amount of 4-cyano-4 (dodecylsulfanylthiocarbonyl) sulfanylpentanoic acid was 2mmol, based on 17mL of 1, 4-dioxane.

In the second step, the dosage of dichloromethane is 20mL, the dosage of dopamine hydrochloride is 30mmol, and the dosage of triethylamine is 60 mmol.

In the third step, the dried product II was dissolved in 20mL of methylene chloride, and 40mmol of methyl iodide was added thereto under nitrogen.

As a result, a hydrophilic polymer Z7 was produced.

Example 1

This example illustrates a modified superhydrophilic web prepared using the method of the present invention.

(1) Dissolving the hydrophilic polymer prepared in preparation example 1 in an acetic acid/sodium acetate buffer solution with pH of 5 to obtain a first copolymer aqueous solution with a concentration of 10 mg/mL;

(2) polyvinylidene fluoride mesh film was cut into 5cm × 5cm pieces at a volume ratio of 1: 1, ultrasonically cleaning the mixed solution of deionized water and ethanol for 30min, and drying the cleaned mixed solution by using nitrogen to obtain a first substrate net film;

(3) soaking the first substrate omentum in 100mL of trihydroxymethyl aminomethane buffer solution with the mass concentration of 6mg/mL, adding 0.2g of dopamine, stirring and reacting for 24 hours, taking out, washing the omentum with deionized water, and drying the omentum with nitrogen to obtain a polydopamine-modified omentum, namely a second substrate omentum;

(4) and soaking the second substrate net film in the first copolymer aqueous solution for 4 hours to obtain a third substrate net film, taking out the third substrate net film, cleaning the third substrate net film with deionized water, and drying the third substrate net film with nitrogen to obtain the hydrophilic polymer network modified super-hydrophilic net film, wherein the mark is S1.

FIG. 2 is a schematic representation of the structure of a hydrophilic polymer network modified superhydrophilic mesh membrane of the present invention in which a hydrophilic polymer network is built on a base mesh membrane by a dopamine coating and hydrophilic crosslinks. Wherein the polymer (copolymer) containing the catechol group, the quaternary amine group and the polyethylene glycol chain can react with the polydopamine coating through various interactions including pi-pi stacking, Michael addition, cation-pi, hydrogen bond, Di-DOPA coupling and the like, and a hydrophilic polymer network is constructed on the surface of the substrate omentum. When wetted with water, the hydrophilic polymer network swells with water to form a thin and stable water film, thereby becoming a barrier to the penetration of various oils and rendering the film with underwater superoleophobic properties to complete the oil/water separation process.

Fig. 3 is an atomic force microscope two-dimensional, three-dimensional imaging picture: in fig. 3, (a), (b), and (c) are two-dimensional atomic force microscope images of the first substrate mesh film prepared in step (2), the second substrate mesh film prepared in step (3), and the third substrate mesh film prepared in step (4) in example 1, respectively; fig. 3 (e), (f), and (g) are atomic force microscope three-dimensional imaging pictures of the first base mesh film prepared in step (2), the second base mesh film prepared in step (3), and the third base mesh film prepared in step (4) in example 1, respectively. From fig. 3, it can be observed that the base web surface is very smooth, providing a rich backbone structure, while the modified membrane surface presents a large number of nanoparticles. The surface roughness can be generally calculated by root mean square Roughness (RMS), the root mean square roughness of the basement membrane is 69.1nm, the RMS of the polydopamine modified membrane surface and the root mean square roughness of the hydrophilic polymer network modified super-hydrophilic omentum surface reach 89.6nm and 99.8nm respectively, and the surface roughness is proved to be greatly improved by the two-step treatment.

FIG. 4 is a scanning electron microscope and corresponding Energy Dispersive Spectroscopy (EDS) image of a third base web prepared in step (4) of example 1 of the present invention: after the membrane is treated by the hydrophilic polymer and polydopamine, an obvious multi-level micro-nano structure is formed on the surface of the membrane, so that the surface roughness is greatly enhanced; the signals of uniform distribution of oxygen and nitrogen elements prove that the polydopamine and catechol functionalized hydrophilic polymer is successfully modified on the polyvinylidene fluoride membrane.

FIG. 5 is an infrared spectroscopy (FTIR) analysis of polyvinylidene fluoride omentum at various stages of processing according to example 1 of the present invention with C-F flexural vibration at 1355cm^-1There is an absorption peak, and the intensity is obviously reduced as the surface modification process is carried out, which is consistent with the subsequent XPS analysis result. 1549cm in the spectra of the PDA-coated film and the CFHP/PDA-coated film^-1The absorption peak is N-H bending vibration, 3000-3500cm^-1The wide absorption peak is the stretching vibration of O-H/N-H, and simultaneously, the hydrophilic polymer network modified super-hydrophilic net film is 1787cm^-1The construction of the hydrophilic polymer network on the surface of the polyvinylidene fluoride membrane was confirmed by the absorption peak appearing at (O ═ C-O bending vibration), which indicated that the modification of the surface of the polyvinylidene fluoride membrane with the polydopamine and hydrophilic copolymer was successful。

Fig. 6(a) is an X-ray photoelectron spectrum (XPS) of the polyvinylidene fluoride web film at different stages of the treatment in example 1 of the present invention, and in fig. 6, as shown in fig. 6(a), 1, 2, 3 are high-fraction C1s spectra of the first, second, and third base web films, respectively, and the major characteristic peaks appear as C1s, N1s, O1s, and F1s corresponding to 290.89eV, 400.89eV, 532.16eV, and 682.28eV, respectively, and after modification, the intensity of the F peak is significantly reduced to as low as 0.47% of the corresponding F element content, and the intensity of the O, N peak is significantly increased, which is in accordance with the analysis result of the basic element content in table 1, and the content of N element in the hydrophilic polymer network modified superhydrophilic web film is increased from 0.44% to 8.07% and the content of O is increased from 0.65% to 22.03% as compared with the original polyvinylidene fluoride film; for the original polyvinylidene fluoride film (FIG. 6b), its high fraction C1s spectrum can be decomposed into three peaks of 291.1eV, 285.7eV, and 284.6eV, corresponding to C-F, C-H and C-C, respectively. While for polydopamine modified membrane (fig. 6C) new peaks of C-O (286.5eV) and C ═ C (285.0eV) appear in the high fraction C1s spectrum, confirming successful modification of polydopamine, for hydrophilic polymer network modified superhydrophilic omentum (fig. 6d) new peaks of O ═ C-O (288.1eV) and C-O-C (286.0eV) in the high fraction C1s spectrum are bonds present during hydrophilic polymer modification and during polymer network formation, again, the analysis results show successful modification of polydopamine and hydrophilic copolymers on the surface of polyvinylidene fluoride membrane.

TABLE 1

Name (R)	Base film (%)	Polydopamine modification (%)	Polymer/polydopamine modification (%)
				C1s	46.8	68.65	69.43
O1s	0.65	19.69	22.03
				N1s	0.44	8.25	8.07
F1s	52.11	3.41	0.47

FIG. 7 is a graph showing the change of contact angle of a water drop in air of a third base web prepared in step (4) of example 1 of the present invention with time, the contact angle of the water drop in air of the original polyvinylidene fluoride film is-110 degrees, and the change of the contact angle with time is not large, which shows that the third base web has stable hydrophobic property; after the dopamine treatment, the instantaneous water drop contact angle of the poly-dopamine modified membrane is enhanced to be about 46 degrees by the hydrophilicity, and is slightly reduced to 40 degrees within 3 min; after the catechol functionalized hydrophilic polymer is coated, the instantaneous water drop contact angle of the hydrophilic polymer network modified super-hydrophilic net film is about 20 ℃, and the water drop is completely spread and soaked in 50s, which shows that the prepared hydrophilic polymer network modified super-hydrophilic net film has strong hydrophilicity.

Fig. 8 shows that the contact angles of the third substrate mesh membrane prepared in step (4) in example 1 of the present invention under water with different oil drops and the contact angles under water with various oils such as petroleum ether, hexane, dichloromethane, toluene, chloroform, gasoline, etc. are all above 160 ℃, which shows super-oleophobic properties under water, and the results shown in fig. 9 prove that the prepared polymer/polydopamine modified mesh membrane has super-hydrophilicity and super-oleophobic properties under water.

FIG. 9 shows the separation efficiency (FIG. 9a) and flux (FIG. 9b) of modified superhydrophilic omentum prepared in example 1 of the present invention applied to separate different oil-water mixtures. As can be seen from FIG. 9a, the hydrophilic polymer network modified super-hydrophilic net membrane shows excellent separation performance when processing various oil-water mixtures, the oil content of the filtrate is as low as 52.6mg/L, the separation efficiency is over 99.96%, and the average separation flux of different oil-water mixtures is about 5586.2L m^-2·h^-1(FIG. 9 b).

FIG. 10 shows the separation efficiency (FIG. 10a) and throughput (FIG. 10b) of the modified superhydrophilic omentum prepared in the first embodiment of the present invention applied to separate different oil-in-water emulsions. When the prepared hydrophilic polymer network modified super-hydrophilic net film is used for separating various oil-in-water emulsions stabilized by using the surfactant, such as gasoline/water/SDS, chloroform/water/SDS, hexane/water/SDS, petroleum ether/water/SDS, dichloromethane/water/SDS and toluene/water/SDS, the average oil content of filtrate is lower than 26.25mg/L and the separation efficiency reaches 99.95 percent (figure 10a), and as can be seen from figure 10b, the separation flux of various water-in-oil emulsions exceeds 1012.35 L.m^-2·h^-1. This is mainly due to the hydrophilic polymer network formed on the surface of the substrate film in the present invention, when wetted by water, the hydrophilic polymer network will form a thin and stable water film along with water swelling, thereby becoming a barrier for various oils to permeate, and making the film have super-oleophobic property under water to complete the oil/water separation process.

FIG. 11 is a view showing an embodiment of the oil-water separator of the present invention; before oil-water emulsion separation (figure b)₁FIG. c₁FIG. d₁) And after separation (FIG. b)₂FIG. c₂FIG. d₂) High power light microscopy pictures of (a). Wherein the diagram b₁FIG. b₂n-hexane/water/SDS, panel c₁FIG. c₂Is chloroform/water/SDS, Panel d₁FIG. d₂Is steamoil/water/SDS. As can be seen from FIG. 10, the three emulsions are opaque before separation, a large number of droplets are uniformly dispersed, and the filtrate after separation becomes transparent and has no obvious droplets, which confirms that the prepared hydrophilic polymer network modified super-hydrophilic net film has excellent separation performance. For the separation of surfactant-stabilized oil-in-water emulsions, the hydrophilic quaternary amine groups and polyethylene glycol chains contained in the catechol-functionalized hydrophilic polymers of the present invention attract the water shells in the oil-in-water emulsion droplets, thereby causing demulsification, after which the micro-oil droplets are continuously coagulated and then blocked by the thin water film formed by the hydrophilic polymer network.

Example 2

(1) The hydrophilic polymer prepared in preparation example 2 was dissolved in an acetic acid/sodium acetate buffer solution having a pH of 5 to obtain a first aqueous copolymer solution having a concentration of 5 mg/mL.

(3) soaking the first substrate omentum in 100mL of trihydroxymethyl aminomethane buffer solution with the mass concentration of 5mg/mL, adding 0.1g of dopamine, stirring and reacting for 24 hours, taking out, washing the omentum with deionized water, and drying the omentum with nitrogen to obtain a polydopamine-modified omentum, namely a second substrate omentum;

(4) and soaking the second substrate net film in the first copolymer aqueous solution for 4 hours to obtain a third substrate net film, taking out the third substrate net film, cleaning the third substrate net film with deionized water, and drying the third substrate net film with nitrogen to obtain the hydrophilic polymer network modified super-hydrophilic net film, wherein the mark is S2.

Example 3

(1) The hydrophilic polymer prepared in preparation example 3 was dissolved in an acetic acid/sodium acetate buffer solution at pH 5 to give a first aqueous copolymer solution having a concentration of 20 mg/mL.

(3) soaking the first substrate omentum in 100mL of trihydroxymethyl aminomethane buffer solution with the mass concentration of 10mg/mL, adding 0.4g of dopamine, stirring and reacting for 24 hours, taking out, washing the omentum with deionized water, and drying the omentum with nitrogen to obtain a polydopamine-modified omentum, namely a second substrate omentum;

(4) and soaking the second substrate net film in the first copolymer aqueous solution for 4 hours to obtain a third substrate net film, taking out the third substrate net film, cleaning the third substrate net film with deionized water, and drying the third substrate net film with nitrogen to obtain the hydrophilic polymer network modified super-hydrophilic net film, wherein the mark is S3.

Example 4

(1) The hydrophilic polymer prepared in preparation example 4 was dissolved in an acetic acid/sodium acetate buffer solution having a pH of 5 to obtain a first aqueous copolymer solution having a concentration of 4 mg/mL.

(3) soaking the first substrate omentum in 100mL of trihydroxymethyl aminomethane buffer solution with the mass concentration of 4mg/mL, adding 0.08g of dopamine, stirring and reacting for 24 hours, taking out, washing the omentum with deionized water, and drying the omentum with nitrogen to obtain a polydopamine-modified omentum, namely a second substrate omentum;

(4) and soaking the second substrate net film in the first copolymer aqueous solution for 4 hours to obtain a third substrate net film, taking out the third substrate net film, cleaning the third substrate net film with deionized water, and drying the third substrate net film with nitrogen to obtain the hydrophilic polymer network modified super-hydrophilic net film, wherein the mark is S4.

Example 5

(1) The hydrophilic polymer prepared in preparation example 5 was dissolved in an acetic acid/sodium acetate buffer solution having a pH of 5 to obtain a first aqueous copolymer solution having a concentration of 22 mg/mL.

(3) soaking the first substrate omentum in 100mL of tris (hydroxymethyl) aminomethane buffer solution with the mass concentration of 5mg/mL, adding 0.5g of dopamine, stirring and reacting for 24 hours, taking out, washing the omentum with deionized water, and drying by blowing with nitrogen to obtain a polydopamine-modified omentum, namely a second substrate omentum;

(4) and soaking the second substrate net film in the first copolymer aqueous solution for 4 hours to obtain a third substrate net film, taking out the third substrate net film, cleaning the third substrate net film with deionized water, and drying the third substrate net film with nitrogen to obtain the hydrophilic polymer network modified super-hydrophilic net film, wherein the mark is S5.

Comparative example 1

According to the disclosure of the document J.Water Process.Eng.34(2020):101121, a polyvinylidene fluoride/polydimethylsiloxane high-pore blend membrane with super hydrophobicity-super lipophilicity is successfully prepared by ethanol induced phase inversion and applied to oil-water separation of oil-in-water emulsion, and is marked as D1.

Comparative example 2

According to the publication J.appl.Polym.Sci. (2020):49546, a nanofiber membrane with multilevel roughness is prepared by an electrostatic spinning method by using a polyvinylidene fluoride and silicon dioxide blended solution as a raw material, and can be applied to separation of various oil-water mixed solutions, and is marked as D2.

Comparative example 3

Modification of graphitic carbo-nitride, graphene oxide and titanium dioxide as novel ternary complexes by hydrothermal method on polyvinylidene fluoride membranes for separation of emulsions in wastewater, as disclosed in Sep, Purif, Technol.241(2020):116709, for separation of emulsions in wastewater, labeled D3

Comparative example 4

According to the document Chemosphere 250 (2020): 126236 ink-jet printing of polyphenols (catechol or tannic acid) and sodium periodate on a polyvinylidene fluoride membrane to improve the oil-water separation performance of the membrane, is labeled as D4.

Comparative example 5

A modified superhydrophilic omentum was prepared in the same manner as in example 1, except that the "hydrophilic polymer prepared in preparative example 1" was replaced with a thiol-terminated hydrophilic polymer disclosed in CN110354536A, labeled D5.

Comparative example 6

A modified superhydrophilic omentum was prepared in the same manner as in example 1, except that the "hydrophilic polymer prepared in preparation 2" was replaced with a copolymer containing polyethylene glycol hydrophilic chains, dimethylaminoethyl hydrophobic chains, and mussel biomimetic catechol groups, as disclosed in CN108671774A, and labeled D6.

Comparative example 7

A modified superhydrophilic mesh film was prepared in the same manner as in example 1, except that the "hydrophilic polymer prepared in preparation example 3" was replaced with a polyfunctional hydrogel copolymer solution containing 3- (2-methacryloyloxyethyldimethylamino) propanesulfonate, acrylamide, a vinyl monomer having a carboxyl group disclosed in CN111467976A, and then cured on the surface of the film using a curing agent, which was labeled D7.

Comparative example 8

A modified superhydrophilic omentum was prepared in the same manner as in example 1, except that the "hydrophilic polymer prepared in preparative example 4" was replaced with the polyamino polymer described in CN109499393A, labeled D8.

Comparative example 9

A modified superhydrophilic omentum was prepared in the same manner as in example 1, except that the hydrophilic polymer prepared in preparation 5 was replaced with the active ester group-containing polyethylene glycol described in CN106422421A, labeled D9.

Comparative example 10

A modified superhydrophilic omentum was prepared in the same manner as in example 1, except that the "hydrophilic polymer prepared in preparative example 1" was replaced with the "hydrophilic polymer prepared in preparative example 6", labeled D10.

Comparative example 11

A modified superhydrophilic omentum was prepared in the same manner as in example 1, except that the "hydrophilic polymer prepared in preparative example 1" was replaced with the "hydrophilic polymer prepared in preparative example 7", labeled D11.

Test example

The separation throughput and separation efficiency of the modified superhydrophilic omentum prepared in examples and comparative examples were tested as technical indicators, and the results are shown in table 2.

TABLE 2

As can be seen from the results of examples 1-5, comparative examples 1-11, and Table 2, the hydrophilic polymer network modified ultra-hydrophilic omentum prepared by the present invention shows good performance in separating immiscible oil-water mixture and surfactant-stabilized oil-in-water emulsion, and has a separation flux of 5641.1 L.m.^-2·h^-1The separation efficiency is as high as 99.98%, and the method has excellent pollution resistance and reusability, and has great application potential in the aspects of oily wastewater treatment, water resource recycling and the like.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A preparation method of a mussel bionic functionalized hydrophilic polymer is characterized by comprising the following steps:

2. The production method according to claim 1, wherein in step (1), 2- (dimethylamino) ethyl methacrylate, polyethanol methacrylate, pentafluorophenol acrylate, 4-cyano-4 (dodecylsulfanylthiocarbonyl) sulfanylpentanoic acid, and the millimolar ratio of the initiator is (5 to 20): (8-16): (5-20): (0.5-2): (0.125-0.5);

preferably, the heating conditions include: the temperature is 65-80 ℃, and the time is 2-5 h; the concentration conditions include: the temperature is 55-65 ℃.

3. The preparation method according to claim 1, wherein the amount of dopamine hydrochloride and triethylamine is used in a millimolar ratio of (5-25) to 10-30mL of 1, 4-dioxane: (10-50);

preferably, in the step (2), the amount of the dichloromethane is 10-35mL relative to 10-30mL of the 1, 4-dioxane;

preferably, in the step (2), the mass ratio of the product I, dopamine hydrochloride, triethylamine and dichloromethane is (3.8-8.8): (1.9-3.8): (1-3.6): (20-40);

preferably, the conditions of the oil bath include: the temperature is 35-40 ℃ and the time is 12-24 h.

Preferably, in step (3), the amount of dichloromethane is 10 to 35mL and the amount of methyl iodide is 10 to 35mmol relative to 10 to 30mL of 1, 4-dioxane.

4. A mussel biomimetic functionalized hydrophilic polymer comprising a quaternary amine group, a polyethylene glycol group and a mussel biomimetic catechol group prepared by the method of any one of claims 1-3.

5. A preparation method of a hydrophilic polymer network modified super-hydrophilic net membrane is characterized by comprising the following steps:

first contacting the mussel biomimetic functionalized hydrophilic polymer of claim 4 with a buffer solution to obtain a polymer solution;

6. The preparation method according to claim 5, wherein, in the step (one), the buffer solution is acetic acid/sodium acetate with pH of 5-5.5;

preferably, the hydrophilic polymer is used in an amount of 5 to 20mg with respect to 1mL of the buffer solution.

7. The production method according to claim 5, wherein, in the step (two), the basement membrane is a polymeric microfiltration membrane;

preferably, the base web is selected from one or more of polytetrafluoroethylene, polypropylene and polyvinylidene fluoride;

preferably, the average pore diameter of the base mesh film is 0.2-0.5 μm;

preferably, the tris buffer solution has a mass concentration of 5-10mg/mL and a pH of 8.5-9;

preferably, the dosage of the dopamine hydrochloride is 0.2-0.4g relative to 100mL of the tris buffer;

preferably, the conditions of the second contacting include: under the condition of magnetic stirring, the temperature is 20-25 ℃, and the time is 24-48 h;

preferably, in step (iii), the impregnation conditions include: the temperature is 20-25 ℃ and the time is 4-6 h.

8. A hydrophilic polymer network modified superhydrophilic mesh membrane prepared by the method of preparation defined in any one of claims 5-7.

9. The hydrophilic polymer network-modified superhydrophilic mesh membrane of claim 8, wherein the hydrophilic polymer network-modified superhydrophilic mesh membrane is a hydrophilic polymer network formed by interaction of a polydopamine coating and a hydrophilic polymer containing quaternary amine groups, polyethylene glycol groups, and mussel biomimetic catechol groups on a substrate mesh membrane;

preferably, the hydrophilic polymer network modified superhydrophilic mesh membrane has an average pore size of 0.2-0.3 μm.

10. Use of a hydrophilic polymer network modified superhydrophilic web according to claim 8 or 9 in an oil-in-water emulsion.

11. Use according to claim 10, wherein the oil-in-water emulsion comprises an oil phase and a water phase; wherein the oil phase is selected from one or more of n-hexane, petroleum ether, toluene, dichloromethane, chloroform, gasoline and diesel oil, and the water phase is water;

preferably, the volume ratio of the used amount of the oil phase to the used amount of the water phase is (1-3): (97-99);

preferably, the oil-in-water emulsion further comprises a surfactant;

preferably, the surfactant is sodium lauryl sulfate and is used in an amount of 0.1-0.3mg per 1mL of the oil-in-water emulsion.