CN119331494B

CN119331494B - A self-repairing polyurea coating and its preparation method and application

Info

Publication number: CN119331494B
Application number: CN202411680444.4A
Authority: CN
Inventors: 武金龙; 王鹏; 田煜坤; 梁珊; 李千芊
Original assignee: North Minzu University
Current assignee: North Minzu University
Priority date: 2024-11-22
Filing date: 2024-11-22
Publication date: 2025-06-20
Anticipated expiration: 2044-11-22
Also published as: CN119331494A

Abstract

The present invention discloses a self-repairing polyurea coating and a preparation method and application thereof. The self-repairing polyurea coating is composed of the following raw materials in the following proportions: polyurea prepolymer: solvent: chain extender = 20-60: 15-40: 5-30; the polyurea prepolymer is composed of the following raw materials in the following proportions: solvent: terminal amino substance: terminal isocyanate substance: organic tin catalyst = 10-25: 10-30: 20-60: 0.1-1. The self-repairing polyurea coating of the present invention has good mechanical properties. At a certain temperature, the hydrogen bonds are destroyed, and the dynamic disulfide bonds show a tendency to move and fuse freely to complete the healing. After returning to room temperature, the hydrogen bonds are reconstructed to lock the disulfide bonds again, so that the oil-water separation membrane has the ability to resist destruction and has the self-repairing function after being destroyed, further improving the durability of the material.

Description

Self-repairing polyurea coating and preparation method and application thereof

Technical Field

The invention belongs to the technical field of new materials and surfaces, and particularly relates to a self-repairing polyurea coating and a preparation method and application thereof.

Background

With the development of industry, oily wastewater is severely threatening the survival of humans and the surrounding environment. Therefore, the field of oil-water separation is increasingly focused. The membrane separation technology is the most energy-saving, environment-friendly and efficient in the existing numerous separation methods, and forms a water film in the separation process so that the membrane has good anti-fouling property, natural products and derivatives thereof are mostly used for constructing special infiltration surfaces in the existing scheme, but the natural product coating is mostly poor in mechanical property, and is difficult to bear long-time scraping and poor in durability in the oil-water separation process.

Materials such as polyurea and polyurethane are widely applied to other fields such as buildings due to excellent waterproof, wear-resistant and corrosion-resistant properties, and are used in the form of foam, sponge and the like for oil-water separation, but the separation effect is poor, the foam is prepared in a simple foaming form, but the foam is difficult to have good anti-fouling and mechanical properties in the oil-water separation field, the sponge is in a substrate mode, meanwhile, the defects of poor anti-fouling property, high energy consumption and the like exist, the prepared material is mostly hydrophobic and oleophilic, and the anti-fouling property of the material is further weakened, so that the durability of the material is influenced.

Polyurea and polyurethane coatings have been well applied in many fields, but have not been reported in the field of oil-water separation, and the convenient preparation method for coating brushing has been studied. This is probably because polyurea can receive slight damage in long-time use, if the self-repairing ability of polyurea is poor, slight damage can not in time repair, can accumulate gradually, leads to the coating performance to drop, damages the oil water separation effect of coating, reduces separation efficiency. The wettability of the existing oil-water separation material with self-repairing capability is also hydrophobic and oleophylic, for example, chinese patent publication No. CN104984564A and publication No. 2015 for 10 months and 21 days disclose an oil-water separation material capable of self-repairing and a preparation method thereof, which are characterized in that fluorine-containing monomers and alkyl-containing monomers are respectively introduced on the basis of traditional polyurethane synthesis to synthesize fluorine-containing N-substituted polyurethane and alkyl-containing N-substituted polyurethane, and the fluorine-containing N-substituted polyurethane and the alkyl-containing N-substituted polyurethane are mixed according to a certain proportion and are subjected to blending spinning to prepare the oil-water separation material (oil-water separation membrane). The oil-water separation material has strong oil-water separation capability and high separation efficiency, and has excellent self-repairing performance. However, the material prepared by the invention has the disadvantages of hydrophobic and oleophilic properties, poor dirt resistance and the like, and the preparation of the material requires complex steps such as blending spinning and the like.

While lipophilic separation materials have fatal weaknesses such as poor dirt resistance, self-repairing oil-water separation materials with super-hydrophilicity have not been reported, and preparation of self-repairing oil-water separation coating materials with super-hydrophilicity still remains a challenge.

Disclosure of Invention

The invention aims to provide a self-repairing polyurea coating and a preparation method and application thereof.

In order to solve the problems existing in the prior art, the invention adopts the following technical scheme:

in a first aspect, the invention provides a self-repairing polyurea coating, which comprises the following raw materials of polyurea prepolymer and solvent, wherein the solvent comprises a chain extender=20-60:15-40:5-30;

The polyurea prepolymer consists of the following raw materials in proportion:

Solvent, amino-terminated substance, isocyanate-terminated substance, organotin catalyst=10-25:10-30:20-60:0.1-1.

Preferably, the solvent is dimethylformamide.

Preferably, the chain extender is 4,4 '-diaminodiphenyl disulfide and oxalyl dihydrazide, and the mass ratio of the 4,4' -diaminodiphenyl disulfide to the oxalyl dihydrazide is 3-9:1-7.

Preferably, the amino-terminated species is a polyetheramine.

Preferably, the isocyanate-terminated material is isophorone diisocyanate.

Preferably, the organotin-based catalyst is dibutyltin dilaurate.

In a second aspect, the present invention provides a method for preparing the polyurea coating according to the first aspect, comprising the steps of:

① Sequentially adding an amino-terminated substance and an isocyanate-terminated substance into dimethylformamide, adding an organotin catalyst, and stirring for 0.5-3h in a water bath at 30-60 ℃ to obtain a polyurea prepolymer containing an isocyanate group-terminated long-chain structure;

② And adding dimethylformamide into the polyurea prepolymer, then adding a chain extender, and stirring for 1-5 hours in a water bath at the temperature of 30-60 ℃ to obtain the polyurea coating.

In a third aspect, the present invention provides a self-repairing oil-water separation membrane, which is obtained by compounding the polyurea coating of the first aspect with a substrate.

In a fourth aspect, the present invention provides a method for preparing the oil-water separation membrane according to the third aspect, comprising the following steps:

① Diluting the polyurea coating of any one of claims 1-6 to 5-30wt%, uniformly brushing on a substrate, and drying;

② Placing into 1-5wt% phytic acid aqueous solution for ultrasonic assembly for 10-30min,

③ Adding 1-5wt% FeCl ₃ water solution with the volume of 1/2-1/10 of that of the phytic acid water solution, continuing ultrasonic assembly for 10-30min, and then flushing unreacted chemical substances by using deionized water;

④ Placing into 1-5wt% of polyethyleneimine water solution, stirring for 1-5h, washing out unreacted chemical substances by using deionized water, and drying.

In a fifth aspect, the present invention provides an application of the self-repairing oil-water separation membrane in the oil-water separation field.

The invention has the advantages and beneficial effects that:

1. The self-repairing polyurea coating provided by the invention uses the 4,4' -diaminodiphenyl disulfide (AD) and Oxalyl Dihydrazide (ODH) with dynamic disulfide bonds as chain extenders, a unique six-fold hydrogen bond is constructed while a double hydrogen bond is constructed, the dynamic disulfide bonds show a tendency of free movement and fusion at a certain temperature so as to finish healing, and the self-healing performance of the whole coating is endowed through the cooperation of the actions of metal coordination bonds, hydrogen bonds and the like of Phytic Acid (PA) and Polyethylenimine (PEI). And the constructed unique hexahydro bond can limit the free movement of the dynamic disulfide bond by using a layered hydrogen bond at room temperature, so that the coating has better mechanical property. The hydrogen bond is destroyed at a certain temperature, the dynamic disulfide bond shows a trend of free movement and fusion so as to finish healing, and after the temperature is restored to the room temperature, the disulfide bond is locked again by the hydrogen bond reconstruction, so that the oil-water separation film has the self-repairing function after being destroyed while having the damage resistance, and the durability of the material is further improved.

2. According to the invention, the super-hydrophilic composite coating is constructed by using hydrophilic substances such as polyurea, phytic acid, polyethyleneimine and the like, and the self-repairing polyurea component has high wear resistance and self-repairing property, and the prepared separation material is super-hydrophilic, so that the oil-water separation membrane has high durability and high stain resistance, and is suitable for various complex oil-water separation environments.

Drawings

FIG. 1 is an infrared spectrum of a sample obtained in each step of example 4, wherein:

SSM is the original stainless steel mesh;

Ssm@shpu is a stainless steel mesh coated with SHPU coating;

ssm@shpu@pa is ssm@shpu subjected to ultrasonic assembly treatment;

ssm@shpu@pa@pei is ssm@shpu@pa treated by PEI;

FIG. 2 is a graph showing the cyclic separation efficiency of the self-repairing oil-water separation membrane of the invention on kerosene/water mixed liquor;

FIG. 3 is a graph showing oil-water separation efficiency of different material samples for different oil-water mixtures;

FIG. 4 is a graph of oil-water separation flux of different material samples for different oil-water mixtures;

FIG. 5 is a flow chart of a self-healing performance test.

Detailed Description

The technical solutions of the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which are obtained by a person skilled in the art based on the embodiments of the present application, fall within the scope of protection of the present application.

The experimental methods in the following examples, unless otherwise specified, are conventional methods, and are carried out according to techniques or conditions described in the literature in the field or according to the product specifications. Materials, reagents and the like used in the examples described below are commercially available unless otherwise specified.

Example 1

The embodiment provides a preparation method of a self-repairing polyurea coating (SHPU), which comprises the following steps:

① Polyurea prepolymers are prepared by adding 20ml of Dimethylformamide (DMF) as solvent to a three-necked flask, subsequently adding 10mmol of the amine-terminated polyetheramine (D2000) and 20mmol of the isocyanate-terminated isophorone diisocyanate (IPDI) in succession, and finally adding 0.13g of dibutyltin dilaurate DBTDL as catalyst. Stirring for 1h in a water bath at 30 ℃ to obtain the polyurea prepolymer with the long-chain structure blocked by the isocyanate groups.

② To 41.93g of polyurea prepolymer was added 30ml of DMF to reduce its viscosity, followed by 10mmol of chain extender and stirring for 3 hours in a water bath at 50℃to give a self-repairing polyurea coating (SHPU). The chain extender consists of Oxalyl Dihydrazide (ODH) and 4,4 '-diaminodiphenyl disulfide (AD), wherein the ratio of the amount of oxalyl dihydrazide to the amount of 4,4' -diaminodiphenyl disulfide material is 5:5.

Example 2

This example provides a method for preparing a self-healing (SHPU) polyurea coating, which differs from example 1 only in the amount of oxalyl dihydrazide to 4,4' -diaminodiphenyl disulfide (AD) material ratio, which is 3:7, and the remainder is the same as example 1.

Example 3

This example provides a method for preparing a self-healing (SHPU) polyurea coating, which differs from example 1 only in the amount of oxalyl dihydrazide to 4,4' -diaminodiphenyl disulfide (AD) material ratio, which is 1:9, and the remainder is the same as example 1.

Example 4

This example provides a method for preparing a self-healing (SHPU) polyurea coating, which differs from example 1 only in the amount of oxalyl dihydrazide and 4,4' -diaminodiphenyl disulfide (AD) in a ratio of 7:3, and the remainder are the same as example 1.

Example 5

This example provides a method for preparing a self-healing (SHPU) polyurea coating, which differs from example 1 only in the amount of oxalyl dihydrazide to 4,4' -diaminodiphenyl disulfide (AD) material ratio, which is 9:1, and the remainder is the same as example 1.

Example 6

The embodiment provides a preparation method of a self-repairing (SHPU) polyurea coating, which comprises the following steps:

① Preparation of polyurea prepolymers 10ml of Dimethylformamide (DMF) are introduced into a three-necked flask as solvent, subsequently further 30mmol of the amine-terminated polyetheramine (D2000) and 60mmol of the isocyanate-terminated isophorone diisocyanate (IPDI) are added in succession, and finally 1g of dibutyltin dilaurate DBTDL is added as catalyst. Stirring for 1h in a water bath at 30 ℃ to obtain the polyurea prepolymer with the long-chain structure blocked by the isocyanate groups.

② To 60g of polyurea prepolymer was added 40ml of DMF to reduce its viscosity, followed by 30mmol of chain extender and stirring for 3 hours in a water bath at 50℃to give a self-repairing polyurea coating (SHPU). The chain extender consists of Oxalyl Dihydrazide (ODH) and 4,4 '-diaminodiphenyl disulfide (AD), and the ratio of the oxalyl dihydrazide to the amount of 4,4' -diaminodiphenyl disulfide substances is 5:5.

Example 7

① Polyurea prepolymers are prepared by adding 25ml of Dimethylformamide (DMF) as solvent to a three-necked flask, subsequently adding in succession 20mmol of the amine-terminated polyetheramine (D2000) and 40mmol of the isocyanate-terminated isophorone diisocyanate (IPDI), and finally adding 0.1g of dibutyltin dilaurate DBTDL as catalyst. Stirring for 1h in a water bath at 30 ℃ to obtain the polyurea prepolymer with the long-chain structure blocked by the isocyanate groups.

② To 20g of polyurea prepolymer was added 15ml of DMF to reduce its viscosity, followed by 20mmol of chain extender and stirring for 3 hours in a water bath at 50℃to give a self-repairing polyurea coating (SHPU). The chain extender consists of Oxalyl Dihydrazide (ODH) and 4,4 '-diaminodiphenyl disulfide (AD), and the ratio of the oxalyl dihydrazide to the amount of 4,4' -diaminodiphenyl disulfide substances is 5:5.

Comparative example 1

This comparative example provides a method for preparing a self-healing (SHPU) polyurea coating, which differs from example 1 only in the chain extender used, which is oxalyl dihydrazide alone, and the remainder is the same as example 1.

Comparative example 2

This comparative example provides a method for preparing a self-healing (SHPU) polyurea coating, which differs from example 1 only in the amount of chain extender, 40mmol in this comparative example, and the remainder are the same as example 1.

Comparative example 3

The comparative example differs from example 1 only in that the chain extender used is 4,4' -diaminodiphenyl disulfide alone, and the remainder is the same as example 1.

Example 8

The embodiment provides a self-repairing oil-water separation film, which is prepared by the following method:

① Firstly, sequentially using ethanol, acetone and deionized water to ultrasonically clean a stainless steel mesh for 10min, and then putting the stainless steel mesh into an oven to be dried at 70 ℃ for standby.

② The polyurea coating SHPU prepared in example 1 was diluted to 10wt% using DMF, uniformly applied to a stainless steel mesh using a 1cm wide brush, and dried in an oven at 70 ℃ to give a polyurea coated stainless steel mesh (ssm@shpu).

③ Ultrasonic assembly is carried out by putting SSM@SHPU into 4wt% Phytic Acid (PA) aqueous solution for 10min, then adding 2wt% FeCl ₃ aqueous solution with the volume of 1/5 of that of the phytic acid aqueous solution, continuing ultrasonic assembly for 10min, and then washing out unreacted chemical substances by using deionized water to obtain the stainless steel mesh (SSM@SHPU@PA) which is treated by phytic acid and FeCl ₃ and is coated with polyurea coating.

④ And (3) putting the SSM@SHPU@PA into a 4wt% PEI aqueous solution, stirring for 3 hours, washing out unreacted chemical substances by using deionized water, and drying to obtain the self-repairing oil-water separation membrane (SSM@SHPU@PA@PEI).

FIG. 1 is an infrared spectrum of the original stainless steel mesh SSM used in step ①, SSM@SHPU prepared in step ②, SSM@SHPU@PA prepared in step ③, and SSM@SHPU@PA@PEI prepared in step ④ of example 4.

As can be seen from FIG. 1, the C=O and N-H peaks at 1631cm ^-1 and 1589cm ^-1, and the C-N peaks at 1380cm ^-1 and 1346cm ^-1 in the SSM@SHPU are both due to the formation of urea bonds, and the stretching vibration of C-H at 2816cm ^-1 and C-O at 1120cm ^-1 are due to the soft segment portion of D2000 in the SHPU. The broad-OH and P-O peaks newly appearing at 3417cm ^-1 and 1120cm ^-1 in SSM@SHPU@PA are attributed to the phosphate groups in the PA. the-NH peak at 3417cm ^-1 and the C-N peak at 1380cm ^-1、1346cm^-1 are enhanced in SSM@SHPU@PA@PEI due to the presence of the NH ₃ ⁺ group.

Example 9

The present example provides a self-repairing oil-water separation membrane, which is different from example 8 only in that the SHPU coating prepared in example 2 is used, and the rest is the same as example 8.

Example 10

The present example provides a self-repairing oil-water separation membrane, which differs from example 8 only in that the SHPU coating prepared in example 3 is used, and the rest is the same as example 8.

Example 11

The present example provides a self-repairing oil-water separation membrane, which differs from example 8 only in that the SHPU coating prepared in example 4 is used, and the rest is the same as example 8.

Example 12

The present example provides a self-repairing oil-water separation membrane, which differs from example 8 only in that the SHPU coating prepared in example 5 is used, and the rest is the same as example 8.

Example 13

The present example provides a self-repairing oil-water separation membrane, which is different from example 8 only in that the SHPU coating prepared in example 6 is used, and the rest is the same as example 8.

Example 14

The present example provides a self-repairing oil-water separation membrane, which differs from example 8 only in that the SHPU coating prepared in example 7 is used, and the rest is the same as example 8.

Comparative example 4

This comparative example provides an oil-water separation membrane, and the comparative example differs from example 8 only in that the SHPU coating prepared in comparative example 1 was used, and the remainder were the same as in example 8.

Comparative example 5

This comparative example provides an oil-water separation membrane, and the comparative example differs from example 8 only in that the SHPU coating prepared in comparative example 2 was used, and the rest was the same as in example 8.

Comparative example 6

This comparative example provides an oil-water separation membrane, and the comparative example differs from example 8 only in that the SHPU coating prepared in comparative example 3 was used, and the rest was the same as in example 8.

Experimental example 1SHPU mechanical property test:

Test grouping:

group one SHPU paint prepared in example 1;

group II SHPU paint prepared in example 2;

group III SHPU paint prepared in example 3;

group IV SHPU paint prepared in example 4;

group five SHPU coatings prepared in example 5;

group six SHPU coatings prepared in example 6;

group seven SHPU coating prepared in example 7;

group eight SHPU coating prepared in comparative example 1;

Group nine SHPU coatings prepared in comparative example 2;

Group ten SHPU coating prepared in comparative example 3;

The test method comprises the following steps:

Filling the prepared SHPU coatings of each group into a polytetrafluoroethylene mould, drying for 24 hours in a 70 ℃ oven to prepare SHPU splines with the dimensions of 50mm multiplied by 6mm multiplied by 1mm, respectively stretching the SHPU splines with the dimensions of 50mm multiplied by 6mm multiplied by 1mm by using a universal material testing machine, and testing the mechanical properties of each group of SHPU;

TABLE 1 mechanical test results

Test results show that SHPU sample bars obtained after the SHPU coatings prepared in the examples 1-7 are dried have certain mechanical properties and self-repairing capability. The SHPU coating prepared in example 1 has the strongest mechanical property and self-repairing capability, because proper hydrogen bond density can be constructed by reasonable chain extender proportion, and a phase separation structure with obvious soft segment area and hard segment area is constructed, so that the SHPU coating has stronger mechanical property. The mechanical property after self-repairing is often based on the mechanical property before repairing, and the SHPU containing a proper number of dynamic disulfide bonds has better self-repairing capability.

The SHPU coating prepared in comparative example 1 has poor mechanical properties and self-repairing ability due to the lack of the 4,4' -diaminodiphenyl disulfide chain extender and the lack of a synergistic effect, resulting in no self-repairing ability, the SHPU coating prepared in comparative example 2 has poor mechanical properties due to the large amount of unreacted amino groups, resulting in poor mechanical properties due to the large amount of the chain extender, and the SHPU coating prepared in comparative example 3 has poor mechanical properties and self-repairing ability due to the lack of the oxalyl dihydrazide chain extender, resulting in the disappearance of the synergistic effect, the reduction of the number of hydrogen bonds on the material structure, and the aggravation of free movement and fusion trend of disulfide bonds, resulting in poor mechanical properties of the material at room temperature.

Experimental example 2 self-healing performance test:

The self-repairing capability is the capability of recovering mechanical property and morphology under specific conditions after the material is damaged, a self-repairing experiment is carried out for testing the repairing property of SHPU@PA@PEI, the test method is shown in figure 5, the SHPU paint prepared in the embodiment 1 is filled into a polytetrafluoroethylene die, the SHPU film is obtained after drying for 24 hours in a 70 ℃ oven, the SHPU film is placed into a 4wt% Phytic Acid (PA) aqueous solution for ultrasonic assembly for 10min, then a 2wt% FeCl ₃ aqueous solution with the volume of 1/5 of the phytic acid aqueous solution is added, unreacted chemical substances are washed out by deionized water after the ultrasonic assembly is continued for 10min, SHPU@PA is obtained, the SHPU@PA is placed into the 4wt% PEI aqueous solution for stirring for 3h, the unreacted chemical substances are washed out by deionized water, the SHPU@PA@PEI film is obtained after drying, the SHPU@PA PEI film is cut into small strips, the SHPU@PEI film is subjected to self-repairing under 80 ℃ repairing condition after two glass slides are compacted, and the self-repairing property of the SHPU film is obtained after the self-repairing condition is completed, and the self-repairing capability of the SHPU@PA film is proved to be excellent after the self-repairing performance of the material is obtained.

Experimental example 3 self-healing efficiency test:

The testing method comprises the following steps:

Filling the SHPU coating prepared in the example 1 into a polytetrafluoroethylene mould, drying the polytetrafluoroethylene mould in a 70 ℃ oven for 24 hours to obtain an SHPU film, putting the SHPU film into a 4wt% Phytic Acid (PA) aqueous solution for ultrasonic assembly for 10 minutes, then adding a 2wt% FeCl ₃ aqueous solution with the volume of 1/5 of the phytic acid aqueous solution, continuing ultrasonic assembly for 10 minutes, washing out unreacted chemical substances by using deionized water to obtain an SHPU@PA film, putting the SHPU@PA film into a 4wt% PEI aqueous solution, stirring the SHPU@PA@PEI film for 3 hours, washing out the unreacted chemical substances by using deionized water, drying to obtain an SHPU@PA@PEI film, and manufacturing the SHPU@PA@PEI film into SHPU@PEI bars with the size of 50mm multiplied by 6mm multiplied by 2 mm.

The shpu@pa@pei spline with dimensions of 50mm×6mm×2mm was stretched and tested for self-healing efficiency (SHE) according to the self-healing efficiency formula. The clamping length between the clamps was 20mm and the stretching speed was 60mm/min, and the test was repeated 3 times for each sample to average. The self-healing efficiency is calculated as follows:

SHE=F₁/F₀×100%

F ₀ is the tensile stress of a conventional original SHPU@PA@PEI spline, F ₁ is the tensile stress after shearing the spline, aligning the notches and self-healing for a certain time at a certain temperature.

The self-repairing efficiency is calculated according to the above formula by placing the SHPU@PA@PEI in an air atmosphere at 80 ℃ for different time periods, and as shown in table 2, the self-repairing efficiency overall shows a tendency of rising and falling along with the prolongation of the repairing treatment time as seen in table 2.

TABLE 2 self-healing efficiency over time

The best self-repairing time of the SHPU@PA@PEI is 1h, and the self-repairing efficiency can reach 90.53%, so that the best self-repairing condition can be obtained to be 1h at 80 ℃.

Experimental example 4 oil-water separation performance test:

Test grouping:

group I SSM@SHPU prepared in example 8.

Group II SSM@SHPU@PA prepared in example 8.

Group III SSM@SHPU@PA@PEI prepared in example 8.

Group IV SSM@SHPU@PA@PEI prepared in example 9;

group five ssm@shpu@pa@pei prepared in example 10;

group six ssm@shpu@pa@pei prepared in example 11;

Group seven ssm@shpu@pa@pei prepared in example 12;

Group eight ssm@shpu@pa@pei prepared in example 13;

Group nine ssm@shpu@pa@pei prepared in example 14;

ten groups of the oil-water separation films prepared in comparative example 4;

eleven groups of the oil-water separation membranes prepared in comparative example 5;

twelve groups of the oil-water separation films prepared in comparative example 6.

The test method comprises the following steps:

each group uses a syringe tube and a long tail clamp to automatically assemble and construct an oil-water separation device, and the oil-water separation performance of mixed liquid of 6 different oils such as normal hexane, toluene, kerosene, diesel oil, gasoline, petroleum ether and the like and deionized water is respectively tested in a gravity driving mode under the room temperature condition. The oil-water separation membranes prepared in each test group were thoroughly wetted with deionized water before use and then fixed between two plastic tubes. All oil solvents were stained using oil red O.

6 Different oils such as normal hexane, toluene, kerosene, diesel oil, gasoline, petroleum ether and the like are respectively mixed with deionized water according to the proportion (20 mL, V oil: V water=1:1) to obtain six oil-water mixed liquids, the six oil-water mixed liquids are poured into the device from the upper pipe opening of the device, after all the water is separated, the water is waited for 10 seconds, and for each sample, the test is repeated for3 times, and the average value is obtained. The Separation Efficiency (SE) and the Separation Flux (SF) were calculated according to the formula (1) and the formula (2), respectively.

SE=V₁/V₀×100%(1)

SF=V₂/st(2)

V ₀ and V ₁ represent the volume of oil (mL) before and after separation, V ₂ represents the volume of water (mL) separated through the separation material, and s and t represent the effective separation area (cm ²) of the separation material and the time(s) taken for oil-water separation, respectively.

The test results are shown in Table 3 and FIGS. 3 and 4.

TABLE 3 separation efficiency and separation flux

As is clear from Table 3, SSM@SHPU@PA@PEI prepared in examples 8-14 has higher separation efficiency and separation flux, comparative example 4 cannot generate a synergistic effect due to the use of a single chain extender, the increase of hydrogen bonds changes the phase separation structure of the material, the mechanical property of the material is poor, the stability of the coating is reduced, the separation effect is reduced due to the fact that the excessive addition of the chain extender influences the phase separation structure of the material, the mechanical property of the material is poor, the stability of the coating is reduced, the separation effect is reduced due to the fact that a large amount of unreacted substances influence the phase separation structure of the material, and comparative example 6 cannot generate a synergistic effect due to the use of a single chain extender, the reduction of hydrogen bonds changes the phase separation structure of the material, the mechanical property of the material is poor, and the stability of the coating is reduced, so that the separation effect is reduced.

As shown in FIG. 3, the average separation efficiency of SSM@SHPU, SSM@SHPU@PA, SSM@SHPU@PA@PEI for six oils is 5.23%, 86.57% and 98.53%, and as shown in FIG. 4, the average separation flux of SSM@SHPU, SSM@SHPU@PA, SSM@SHPU@PA@PEI for six oils is 19627.21L/m ²/h、11436.75L/m²/h、11748.67L/m²/h. As can be seen from FIGS. 3 and 4, the present invention forms a coating layer with a certain hydrophilicity on the surface of SHPU by chelating between phytic acid and iron ions, and by coordinating, hydrogen bonding, etc.

According to the invention, the phytic acid is negatively charged, the polyethyleneimine is positively charged, and the polyethyleneimine is attached to the surface of the phytic acid through electrostatic interaction, so that micro-nano-scale roughness is constructed, and the hydrophilicity of the coating is further increased.

Experimental example 5 cycle separation performance test:

In order to test whether SSM@SHPU@PA@PEI can exert self-repairing performance in oil-water separation, a cyclic separation test is carried out.

Test grouping:

Self-repairing group SSM@SHPU@PA@PEI prepared in example 8;

self-healing group 1 SSM@SHPU@PA@PEI prepared in example 8.

Self-repairing group 2 oil-water separation film prepared by adopting comparative example 4.

The test method comprises the following steps:

And (3) performing a cyclic separation test on three groups of materials by using an oil-water mixture formed by 10ml of water and 10ml of kerosene, wherein in the test process, the self-repairing group 1 and the self-repairing group 2 are subjected to self-repairing at 80 ℃ after each 4 times of cyclic separation, the cyclic separation is continued until the cyclic separation is completed, the cyclic separation is performed until the cyclic separation is completed for 32 times, and the self-repairing group is not subjected to cyclic separation until the cyclic separation is completed for 32 times, and no self-repairing treatment is performed in the middle.

Test results:

As shown in fig. 2, in the cycle separation efficiency graph of the self-repairing oil-water separation membrane prepared in example 8 on the kerosene/water mixture, in the cycle separation test of 32 times, it can be seen that the separation efficiency of the self-repairing-free group and the self-repairing-free group 2 is obviously higher than that of the self-repairing-free group 1, and when the separation is performed for 32 times, the separation efficiency of the self-repairing-free group is reduced by 2.14%, the separation efficiency of the self-repairing-free group 2 is reduced by 4.60%, and the separation efficiency of the self-repairing-free group 1 is reduced by only 0.87%. After 32 cycles of separation, the separation efficiency of the no self-repairing group SSM@SHPU@PA@PEI is 96.3%, and the separation efficiency of the self-repairing group 1 is 97.6% and is higher than 1.3%.

As can be seen from the above experiments, the self-repairing oil-water separation film prepared in example 8 has a synergistic effect by combining ODH and AD chain extenders, the mechanical properties of the coating material are ensured, the self-repairing capability of the material is provided, the oil-water separation circulation effect of the self-repairing group 1 is obviously better than that of the oil-water separation film without the self-repairing group, and the oil-water separation film prepared in comparative example 4 cannot generate a synergistic effect due to the lack of the AD chain extender, so that the self-repairing effect is not generated. And the use of a single ODH chain extender leads to the reduction of the mechanical property of the coating material, so that the coating material is difficult to bear multiple scour of an oil-water mixture, and the oil-water separation and circulation effect is poor.

The embodiments of the present application have been described above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present application and the scope of the claims, which are to be protected by the present application.

Claims

1. The preparation method of the oil-water separation membrane is characterized by comprising the following steps of:

① Diluting the polyurea coating to 5-30wt% and uniformly brushing the polyurea coating on a substrate, and drying;

② Placing into 1-5wt% phytic acid water solution for ultrasonic assembly for 10-30min;

③ Adding 1-5wt% FeCl ₃ water solution with the volume of 1/2-1/10 of that of the phytic acid water solution, continuing ultrasonic assembly for 10-30min, and then washing out unreacted chemical substances by using deionized water;

④ Placing the mixture into a 1-5wt% polyethyleneimine water solution, stirring for 1-5h, washing out unreacted chemical substances by using deionized water, and drying;

the preparation method of the polyurea coating comprises the following steps:

① Preparing polyurea prepolymer, namely adding 20ml of dimethylformamide into a three-mouth bottle to serve as a solvent, sequentially adding 10mmol of polyetheramine and 20mmol of isophorone diisocyanate, finally adding 0.13g of dibutyltin dilaurate to serve as a catalyst, and stirring for 1h in a water bath at the temperature of 30 ℃ to obtain the polyurea prepolymer with an isocyanate group-terminated long-chain structure;

② 30ml of dimethylformamide was added to 41.93g of polyurea prepolymer to reduce its viscosity, followed by addition of 10mmol of chain extender, and stirring in a water bath at 50℃for 3 hours to obtain a polyurea coating;

The chain extender is 4,4 '-diaminodiphenyl disulfide and oxalyl dihydrazide, and the mass ratio of the 4,4' -diaminodiphenyl disulfide to the oxalyl dihydrazide is 3-9:1-7.

2. An oil-water separation membrane prepared by the method for preparing an oil-water separation membrane according to claim 1.

3. The use of the oil-water separation membrane according to claim 2 in the field of oil-water separation.