A self-healing polyurea coating, its preparation method and application

Abstract

The present invention discloses a self-healing polyurea coating, its preparation method and application. A self-healing 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: amino-terminated substance: isocyanate-terminated substance: organotin catalyst = 10-25: 10-30: 20-60: 0.1-1. The self-healing polyurea coating of the present invention has good mechanical properties. At a certain temperature, hydrogen bonds are broken, and dynamic disulfide bonds show a tendency of free movement and fusion to complete healing. After returning to room temperature, hydrogen bonds are reconfigured to lock the disulfide bonds again, enabling the oil-water separation membrane to have the ability to resist damage while having the self-healing function after being damaged, further improving the durability of the material.

Description

Technical Field

[0001] The present invention belongs to the field of new materials and surface technology, and particularly relates to a self-healing polyurea coating, a preparation method thereof, and an application thereof. Background Art

[0002] With the development of industry, oily wastewater is seriously threatening the survival of human beings and the surrounding environment. Therefore, people are paying more and more attention to the field of oil-water separation. Membrane separation technology is the most energy-saving, environmentally friendly and efficient among many existing separation methods, and a water film will be formed during the separation process, making it have good anti-fouling properties. In existing solutions, natural products and their derivatives are mostly used to construct special wettable surfaces. However, most natural product coatings have poor mechanical properties and are difficult to withstand long-term scratching during the oil-water separation process, resulting in poor durability.

[0003] Materials such as polyurea and polyurethane are widely used in other fields such as construction due to their excellent waterproof, wear-resistant, corrosion-resistant and other properties. When polyurea, polyurethane and other materials are used for oil-water separation, they are mostly used in the form of foams, sponges, etc. However, the separation effect is not good. Although the foam form is prepared by a simple foaming method, it is difficult to have good anti-fouling properties and mechanical properties in the field of oil-water separation. The sponge form mostly exists in the form of a substrate, and at the same time has disadvantages such as poor anti-fouling properties and high energy consumption. The prepared materials are mostly hydrophobic and oleophilic, further weakening the anti-fouling properties of the materials, thus affecting the durability of the materials.

[0004] Polyurea and polyurethane coatings have been well applied in many fields, but there are few reports in the field of oil-water separation, and there is also little research on the convenient preparation method by painting with coatings. This may be because polyurea will be slightly damaged during long-term use. If the self-healing ability of polyurea is poor, tiny damages cannot be repaired in time, and will gradually accumulate, resulting in a decline in the coating performance, damaging the oil-water separation effect of the coating, and reducing the separation efficiency. Most of the existing oil-water separation materials with self-healing ability also have a hydrophobic and oleophilic wettability. For example, a Chinese invention patent with a publication number of CN104984564A and a publication date of October 21, 2015 discloses a self-healing oil-water separation material and a preparation method thereof. On the basis of traditional polyurethane synthesis, a fluorine-containing monomer and an alkyl-containing monomer are respectively introduced to synthesize fluorine-containing N-substituted polyurethane and alkyl-containing N-substituted polyurethane, and the two are mixed in a certain proportion and subjected to co-blending spinning to obtain the oil-water separation material (oil-water separation membrane) of this invention. The oil-water separation material of this invention has strong oil-water separation ability and high separation efficiency; and the oil-water separation material of this invention has very excellent self-healing performance. However, the material prepared by this invention patent is hydrophobic and oleophilic, and has disadvantages such as poor anti-fouling properties, and the preparation of the material requires complex steps such as co-blending spinning.

[0005] The lipophilic separation material has fatal weaknesses such as poor anti-fouling property, while there are few reports on the self-healing oil-water separation material with superhydrophilicity. Preparing a self-healing oil-water separation coating material with superhydrophilicity is still a challenge. Summary of the Invention

[0006] The purpose of the present invention is to provide a self-healing polyurea coating and its preparation method and application.

[0007] In order to solve the problems existing in the prior art, the technical solution adopted by the present invention is:

[0008] In the first aspect, the present invention provides a self-healing polyurea coating, which is composed of the following raw materials in the following proportions: polyurea prepolymer: solvent: chain extender = 20 - 60: 15 - 40: 5 - 30;

[0009] The polyurea prepolymer is composed of the following raw materials in the following proportions:

[0010] Solvent: amino-terminated substance: isocyanate-terminated substance: organotin catalyst = 10 - 25: 10 - 30: 20 - 60: 0.1 - 1.

[0011] Preferably, the solvent is dimethylformamide.

[0012] Preferably, the chain extender is 4,4'-diaminodiphenyl disulfide and oxalyl dihydrazide, and the molar ratio of 4,4'-diaminodiphenyl disulfide to oxalyl dihydrazide is 3 - 9: 1 - 7.

[0013] Preferably, the amino-terminated substance is polyetheramine.

[0014] Preferably, the isocyanate-terminated substance is isophorone diisocyanate.

[0015] Preferably, the organotin catalyst is dibutyltin dilaurate.

[0016] In the second aspect, the present invention provides a preparation method of the polyurea coating described in the first aspect above, including the following steps:

[0017] ① Add the amino-terminated substance and the isocyanate-terminated substance to dimethylformamide in sequence, and finally add the organotin catalyst, and stir in a water bath at 30 - 60 °C for 0.5 - 3 h to obtain a polyurea prepolymer with a long-chain structure capped with isocyanate groups;

[0018] ② Add dimethylformamide to the polyurea prepolymer, and then add the chain extender, and stir in a water bath at 30 - 60 °C for 1 - 5 h to obtain the polyurea coating.

[0019] In the third aspect, the present invention provides a self-healing oil-water separation membrane, which is obtained by compounding the polyurea coating described in the first aspect above with a substrate.

[0020] Fourthly, the present invention provides a method for preparing the oil-water separation membrane described in the third aspect above, comprising the following steps:

[0021] ① Dilute the polyurea coating described in any one of claims 1-6 to 5-30 wt%, uniformly apply it on a substrate, and dry it;

[0022] ② Put it into an aqueous solution of phytic acid with a concentration of 1-5 wt% for ultrasonic assembly for 10-30 min,

[0023] ③ Add an aqueous solution of FeCl3 with a concentration of 1-5 wt% and a volume of 1 / 2-1 / 10 of the aqueous solution of phytic acid, continue ultrasonic assembly for 10-30 min, and then rinse off the unreacted chemical substances with deionized water;

[0024] ④ Put it into an aqueous solution of polyethyleneimine with a concentration of 1-5 wt% and stir for 1-5 h, rinse off the unreacted chemical substances with deionized water, and dry it.

[0025] Fifthly, the present invention provides an application of the self-healing oil-water separation membrane described in the fourth aspect above in the field of oil-water separation.

[0026] The advantages and beneficial effects of the present invention are as follows:

[0027] 1. The self-healing polyurea coating of the present invention uses 4,4'-diaminodiphenyl disulfide (AD) and oxalyl dihydrazide (ODH) with dynamic disulfide bonds as chain extenders to construct a unique six-fold hydrogen bond while constructing a double hydrogen bond. The dynamic disulfide bonds tend to move freely and fuse at a certain temperature to complete healing. Through the cooperation of the metal coordination bonds, hydrogen bonds, etc. of phytic acid (PA) and polyethyleneimine (PEI), the whole coating is given self-healing performance. And the unique six-fold hydrogen bond constructed can restrict the free movement of dynamic disulfide bonds at room temperature using hierarchical hydrogen bonds, making the coating have good mechanical properties. At a certain temperature, the hydrogen bonds are broken, and the dynamic disulfide bonds tend to move freely and fuse to complete healing. After returning to room temperature, the hydrogen bonds are reconstructed to lock the disulfide bonds again, enabling the oil-water separation membrane to have the ability to resist damage and the self-healing function after being damaged, further improving the durability of the material.

[0028] 2. Since the present invention uses polyurea and hydrophilic substances such as phytic acid and polyethyleneimine to construct a super-hydrophilic composite coating, and the self-healing polyurea component itself has high wear resistance and self-healing properties, and the prepared separation material is super-hydrophilic, the oil-water separation membrane is given high durability and high anti-fouling properties, and is suitable for various complex oil-water separation environments. Description of the Drawings

[0029] Figure 1Infrared spectra of the samples obtained in each step of Example 4; wherein:

[0030] SSM is the original stainless steel mesh;

[0031] SSM@SHPU is the stainless steel mesh coated with SHPU coating;

[0032] SSM@SHPU@PA is the SSM@SHPU after ultrasonic assembly treatment;

[0033] SSM@SHPU@PA@PEI is the SSM@SHPU@PA after PEI treatment;

[0034] Figure 2 The cyclic separation efficiency diagram of the self-healing oil-water separation membrane of the present invention for kerosene / water mixture;

[0035] Figure 3 The oil-water separation efficiency diagrams of different material samples for different oil-water mixtures;

[0036] Figure 4 The oil-water separation flux diagrams of different material samples for different oil-water mixtures;

[0037] Figure 5 The flow chart of the self-healing performance test. Specific Embodiments

[0038] Next, the technical solutions in the embodiments of the present application will be clearly described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0039] The experimental methods in the following embodiments are all conventional methods unless otherwise specified, and are carried out according to the techniques or conditions described in the literature in this field or according to the product instructions. The materials, reagents, etc. used in the following embodiments can be obtained from commercial channels unless otherwise specified.

[0040] Example 1

[0041] This example provides a preparation method of a self-healing polyurea coating (SHPU), including the following steps:

[0042] ① Preparation of polyurea prepolymer: Add 20 ml of dimethylformamide (DMF) into a three-necked flask as a solvent, and then sequentially add 10 mmol of the amino-terminated substance polyetheramine (D2000) and 20 mmol of the isocyanate-terminated substance isophorone diisocyanate (IPDI). Finally, add 0.13 g of dibutyltin dilaurate DBTDL as a catalyst. Stir for 1 h in a water bath at 30 °C to obtain a polyurea prepolymer with a long-chain structure capped with isocyanate groups.

[0043] ② Add 30 ml of DMF to 41.93 g of the polyurea prepolymer to reduce its viscosity, and then add 10 mmol of the chain extender. Stir for 3 h in a water bath at 50 °C to obtain a self-healing polyurea coating (SHPU). The chain extender is composed of oxalyl dihydrazide (ODH) and 4,4'-diaminodiphenyl disulfide (AD), and the molar ratio of oxalyl dihydrazide to 4,4'-diaminodiphenyl disulfide is 5:5.

[0044] Example 2

[0045] This example provides a method for preparing a self-healing (SHPU) polyurea coating. The difference between this example and Example 1 is only the molar ratio of oxalyl dihydrazide and 4,4'-diaminodiphenyl disulfide (AD). In this example, the molar ratio of oxalyl dihydrazide to 4,4'-diaminodiphenyl disulfide is 3:7, and the rest are the same as in Example 1.

[0046] Example 3

[0047] This example provides a method for preparing a self-healing (SHPU) polyurea coating. The difference between this example and Example 1 is only the molar ratio of oxalyl dihydrazide and 4,4'-diaminodiphenyl disulfide (AD). In this example, the molar ratio of oxalyl dihydrazide to 4,4'-diaminodiphenyl disulfide is 1:9, and the rest are the same as in Example 1.

[0048] Example 4

[0049] This example provides a method for preparing a self-healing (SHPU) polyurea coating. The difference between this example and Example 1 is only the molar ratio of oxalyl dihydrazide and 4,4'-diaminodiphenyl disulfide (AD). In this example, the molar ratio of oxalyl dihydrazide to 4,4'-diaminodiphenyl disulfide is 7:3, and the rest are the same as in Example 1.

[0050] Example 5

[0051] This example provides a method for preparing a self-healing (SHPU) polyurea coating. The difference between this example and Example 1 is only the molar ratio of oxalyl dihydrazide and 4,4'-diaminodiphenyl disulfide (AD). In this example, the molar ratio of oxalyl dihydrazide to 4,4'-diaminodiphenyl disulfide is 9:1, and the rest is the same as in Example 1.

[0052] Example 6

[0053] This example provides a method for preparing a self-healing (SHPU) polyurea coating, including the following steps:

[0054] ① Prepare the polyurea prepolymer: Add 10 ml of dimethylformamide (DMF) into a three-necked flask as a solvent, and then sequentially add 30 mmol of the terminal amino substance polyetheramine (D2000) and 60 mmol of the terminal isocyanate substance isophorone diisocyanate (IPDI). Finally, add 1 g of dibutyltin dilaurate DBTDL as a catalyst. Stir for 1 h in a 30 °C water bath to obtain a polyurea prepolymer with a long-chain structure capped with isocyanate groups.

[0055] ② Add 40 ml of DMF to 60 g of the polyurea prepolymer to reduce its viscosity, and then add 30 mmol of the chain extender. Stir for 3 h in a 50 °C water bath to obtain a self-healing polyurea coating (SHPU). The chain extender is composed of oxalyl dihydrazide (ODH) and 4,4'-diaminodiphenyl disulfide (AD), and the molar ratio of oxalyl dihydrazide to 4,4'-diaminodiphenyl disulfide is 5:5.

[0056] Example 7

[0057] This example provides a method for preparing a self-healing (SHPU) polyurea coating, including the following steps:

[0058] ① Prepare the polyurea prepolymer: Add 25 ml of dimethylformamide (DMF) into a three-necked flask as a solvent, and then sequentially add 20 mmol of the terminal amino substance polyetheramine (D2000) and 40 mmol of the terminal isocyanate substance isophorone diisocyanate (IPDI). Finally, add 0.1 g of dibutyltin dilaurate DBTDL as a catalyst. Stir for 1 h in a 30 °C water bath to obtain a polyurea prepolymer with a long-chain structure capped with isocyanate groups.

[0059] ② Add 15 ml of DMF to 20 g of the polyurea prepolymer to reduce its viscosity, and then add 20 mmol of the chain extender. Stir for 3 h in a 50 °C water bath to obtain a self-healing polyurea coating (SHPU). The chain extender is composed of oxalyl dihydrazide (ODH) and 4,4'-diaminodiphenyl disulfide (AD), and the molar ratio of oxalyl dihydrazide to 4,4'-diaminodiphenyl disulfide is 5:5.

[0060] Comparative Example 1

[0061] This comparative example provides a method for preparing a self-healing (SHPU) polyurea coating. The difference between this comparative example and Example 1 is only the chain extender used. The chain extender in this comparative example is only oxalyl dihydrazide, and the rest are the same as in Example 1.

[0062] Comparative Example 2

[0063] This comparative example provides a method for preparing a self-healing (SHPU) polyurea coating. The difference between this comparative example and Example 1 is only the dosage of the chain extender. The dosage of the chain extender in this comparative example is 40 mmol, and the rest are the same as in Example 1.

[0064] Comparative Example 3

[0065] The difference between this comparative example and Example 1 is only the chain extender used. The chain extender in this comparative example is only 4,4'-diaminodiphenyl disulfide, and the rest are the same as in Example 1.

[0066] Example 8

[0067] This example provides a self-healing oil-water separation membrane, which is prepared by the following method:

[0068] ① First, ultrasonically clean the stainless steel mesh with ethanol, acetone and deionized water in sequence for 10 min, and then put it into an oven to dry at 70 °C for later use.

[0069] ② Dilute the polyurea coating SHPU prepared in Example 1 with DMF to 10 wt%, and use a 1 cm wide brush to evenly coat it on the stainless steel mesh, and dry it in an oven at 70 °C to obtain a stainless steel mesh coated with a polyurea coating (SSM@SHPU).

[0070] ③ Put SSM@SHPU into a 4 wt% aqueous solution of phytic acid (PA) for ultrasonic assembly for 10 min, then add a 2 wt% aqueous solution of FeCl3 with a volume of 1 / 5 of the phytic acid aqueous solution, continue ultrasonic assembly for 10 min, and then use deionized water to wash away the unreacted chemicals to obtain a stainless steel mesh coated with a polyurea coating treated with phytic acid and FeCl3 (SSM@SHPU@PA).

[0071] ④ Put SSM@SHPU@PA into a 4 wt% aqueous solution of PEI and stir for 3 h, use deionized water to wash away the unreacted chemicals, and dry to obtain a self-healing oil-water separation membrane (SSM@SHPU@PA@PEI).

[0072] Figure 1Infrared spectra of the original stainless steel mesh SSM used in step ① of Example 4, SSM@SHPU prepared in step ②, SSM@SHPU@PA prepared in step ③, and SSM@SHPU@PA@PEI prepared in step ④.

[0073] According to Figure 1 it can be seen that the C=O peak and N-H peak appearing at 1631 cm -1 and 1589 cm -1 , as well as the C-N peaks appearing at 1380 cm -1 and 1346 cm -1 , are all attributed to the formation of urea bonds. The stretching vibration of C-H appearing at 2816 cm -1 and the stretching vibration of C-O appearing at 1120 cm -1 are attributed to the soft segment part composed of D2000 in SHPU. The newly emerged -OH broad peak and P-O peak at 3417 cm -1 and 1120 cm -1 in SSM@SHPU@PA are attributed to the phosphate groups in PA. In SSM@SHPU@PA@PEI, due to the presence of the NH3 + group, the -NH peak at 3417 cm -1 and the C-N peaks at 1380 cm -1 , 1346 cm -1 are enhanced.

[0074] Example 9

[0075] This example provides a self-healing oil-water separation membrane. The difference between this example and Example 8 is only that: the SHPU coating prepared in Example 2 is used, and the rest are the same as in Example 8.

[0076] Example 10

[0077] This example provides a self-healing oil-water separation membrane. The difference between this example and Example 8 is only that: the SHPU coating prepared in Example 3 is used, and the rest are the same as in Example 8.

[0078] Example 11

[0079] This example provides a self-healing oil-water separation membrane. The difference between this example and Example 8 is only that: the SHPU coating prepared in Example 4 is used, and the rest are the same as in Example 8.

[0080] Example 12

[0081] This example provides a self-healing oil-water separation membrane. The difference between this example and Example 8 is only that: the SHPU coating prepared in Example 5 is used, and the rest are the same as in Example 8.

[0082] Example 13

[0083] This example provides a self-healing oil-water separation membrane. The difference between this example and Example 8 is only that the SHPU coating prepared in Example 6 is used, and the rest are the same as in Example 8.

[0084] Example 14

[0085] This example provides a self-healing oil-water separation membrane. The difference between this example and Example 8 is only that the SHPU coating prepared in Example 7 is used, and the rest are the same as in Example 8.

[0086] Comparative Example 4

[0087] This comparative example provides an oil-water separation membrane. The difference between this comparative example and Example 8 is only that the SHPU coating prepared in Comparative Example 1 is used, and the rest are the same as in Example 8.

[0088] Comparative Example 5

[0089] This comparative example provides an oil-water separation membrane. The difference between this comparative example and Example 8 is only that the SHPU coating prepared in Comparative Example 2 is used, and the rest are the same as in Example 8.

[0090] Comparative Example 6

[0091] This comparative example provides an oil-water separation membrane. The difference between this comparative example and Example 8 is only that the SHPU coating prepared in Comparative Example 3 is used, and the rest are the same as in Example 8.

[0092] Experimental Example 1 SHPU Mechanical Property Test:

[0093] Test Grouping:

[0094] Group 1: SHPU coating prepared in Example 1;

[0095] Group 2: SHPU coating prepared in Example 2;

[0096] Group 3: SHPU coating prepared in Example 3;

[0097] Group 4: SHPU coating prepared in Example 4;

[0098] Group 5: SHPU coating prepared in Example 5;

[0099] Group 6: SHPU coating prepared in Example 6;

[0100] Group 7: SHPU coating prepared in Example 7;

[0101] Group 8: SHPU coating prepared in Comparative Example 1;

[0102] Group Nine: SHPU coating prepared in Comparative Example 2;

[0103] Group Ten: SHPU coating prepared in Comparative Example 3;

[0104] Test method:

[0105] Fill the SHPU coatings prepared in each group into a polytetrafluoroethylene mold and dry them in an oven at 70 °C for 24 h to prepare SHPU strips with dimensions of 50 mm × 6 mm × 1 mm. Use a universal material testing machine to stretch the SHPU strips with dimensions of 50 mm × 6 mm × 1 mm respectively to test the mechanical properties of each group of SHPU;

[0106] Table 1 Test results of mechanical properties

[0107]

[0108] The test results show that: The SHPU strips obtained after drying the SHPU coatings prepared in Examples 1-7 all have certain mechanical properties and self-healing ability. Among them, the SHPU coating prepared in Example 1 has the strongest mechanical properties and self-healing ability. This is because a reasonable chain extender ratio can construct a suitable hydrogen bond density, construct a phase separation structure with obvious soft segment regions and hard segment regions, and endow SHPU with strong mechanical properties. The level of the mechanical properties after self-healing is often based on the mechanical properties before repair. SHPU with good mechanical properties before repair and containing an appropriate number of dynamic disulfide bonds has good self-healing ability.

[0109] The mechanical properties and self-healing ability of the SHPU coating prepared in Comparative Example 1 are poor. This is because Comparative Example 1 lacks the chain extender 4,4'-diaminodiphenyl disulfide and lacks the synergistic effect, resulting in no self-healing performance; the mechanical properties and self-healing ability of the SHPU coating prepared in Comparative Example 2 are poor. This is because the amount of the chain extender is relatively large, and there are a large number of unreacted amino groups, resulting in poor mechanical properties; the mechanical properties and self-healing ability of the SHPU coating prepared in Comparative Example 3 are poor. This is because the chain extender oxalyl dihydrazide is lacking, resulting in the disappearance of the synergistic effect, a reduction in the number of hydrogen bonds in the material structure, and an increase in the free movement and fusion trend of disulfide bonds, thus resulting in poor mechanical properties of the material at room temperature.

[0110] Self-healing performance test of Experimental Example 2:

[0111] Self-healing ability is the ability of a material to restore its mechanical properties and morphology under specific conditions after being damaged. To test the repair performance of SHPU@PA@PEI, a self-healing experiment was carried out. The test method is as Figure 5As shown, the SHPU coating prepared in Example 1 was filled into a polytetrafluoroethylene mold and dried in an oven at 70 °C for 24 h to obtain an SHPU film. The SHPU film was placed in a 4 wt% aqueous solution of phytic acid (PA) and subjected to ultrasonic assembly for 10 min. Subsequently, a 2 wt% aqueous solution of FeCl3 with a volume of 1 / 5 of the phytic acid aqueous solution was added, and ultrasonic assembly was continued for 10 min. After that, unreacted chemicals were rinsed off with deionized water to obtain SHPU@PA. The SHPU@PA was placed in a 4 wt% aqueous solution of PEI and stirred for 3 h. Unreacted chemicals were rinsed off with deionized water, and after drying, an SHPU@PA@PEI film was obtained. The SHPU@PA@PEI film was cut into small strips, compacted with two glass slides, and self-healed under self-healing conditions at 80 °C. After the self-healing was completed, the glass slides were removed, and a complete SHPU@PA@PEI film could be obtained again, demonstrating that SHPU@PA@PEI has excellent self-healing performance and providing the possibility for the reuse of oil-water separation materials after damage.

[0112] Experimental Example 3 Self-healing Efficiency Test:

[0113] Test Method:

[0114] The SHPU coating prepared in Example 1 was filled into a polytetrafluoroethylene mold and dried in an oven at 70 °C for 24 h to obtain an SHPU film. The SHPU film was placed in a 4 wt% aqueous solution of phytic acid (PA) and subjected to ultrasonic assembly for 10 min. Subsequently, a 2 wt% aqueous solution of FeCl3 with a volume of 1 / 5 of the phytic acid aqueous solution was added, and ultrasonic assembly was continued for 10 min. After that, unreacted chemicals were rinsed off with deionized water to obtain an SHPU@PA film. The SHPU@PA film was placed in a 4 wt% aqueous solution of PEI and stirred for 3 h. Unreacted chemicals were rinsed off with deionized water, and after drying, an SHPU@PA@PEI film was obtained. The SHPU@PA@PEI film was made into an SHPU@PA@PEI spline with dimensions of 50 mm × 6 mm × 2 mm.

[0115] The SHPU@PA@PEI spline with dimensions of 50 mm × 6 mm × 2 mm was stretched, and its self-healing efficiency (SHE) was tested according to the self-healing efficiency formula. The clamping length between the clamps was 20 mm, and the stretching speed was 60 mm / min. For each sample, the test was repeated 3 times and the average value was taken. The self-healing efficiency was calculated according to the following formula:

[0116] SHE = F1 / F0 × 100%

[0117] F0 is the tensile stress of the conventional original SHPU@PA@PEI spline; F1 is the tensile stress after the spline is cut, the cut is aligned, and self-healing occurs at a certain temperature for a certain time.

[0118] The SHPU@PA@PEI was placed in an air atmosphere at 80 °C for different durations, and the self-healing efficiency was calculated according to the above formula. As shown in Table 2, it can be seen from Table 2 that the self-healing efficiency generally shows a trend of first increasing and then decreasing with the extension of the repair treatment time.

[0119] Table 2 Variation of self-healing efficiency with time

[0120]

[0121] The optimal self-healing time of SHPU@PA@PEI is 1 h, and the self-healing efficiency can reach 90.53%. Thus, the optimal self-healing condition is 1 h at 80 °C.

[0122] Experimental Example 4 Oil-water separation performance test:

[0123] Test grouping:

[0124] Group 1: SSM@SHPU prepared in Example 8.

[0125] Group 2: SSM@SHPU@PA prepared in Example 8.

[0126] Group 3: SSM@SHPU@PA@PEI prepared in Example 8.

[0127] Group 4: SSM@SHPU@PA@PEI prepared in Example 9;

[0128] Group 5: SSM@SHPU@PA@PEI prepared in Example 10;

[0129] Group 6: SSM@SHPU@PA@PEI prepared in Example 11;

[0130] Group 7: SSM@SHPU@PA@PEI prepared in Example 12;

[0131] Group 8: SSM@SHPU@PA@PEI prepared in Example 13;

[0132] Group 9: SSM@SHPU@PA@PEI prepared in Example 14;

[0133] Group 10: Oil-water separation membrane prepared in Comparative Example 4;

[0134] Group 11: Oil-water separation membrane prepared in Comparative Example 5;

[0135] Group 12: Oil-water separation membrane prepared in Comparative Example 6.

[0136] Test method:

[0137] For each group, a syringe barrel and a long-tail clip were used to self-assemble and build an oil-water separation device. Under room temperature conditions, the oil-water separation performance of six different oils, namely n-hexane, toluene, kerosene, diesel, gasoline, and petroleum ether, mixed with deionized water was tested by gravity-driven method. Before use, the oil-water separation membranes prepared by each test group were fully wetted with deionized water and then fixed between two plastic pipe barrels. All oil solvents were dyed with Oil Red O.

[0138] Six different oils, namely n-hexane, toluene, kerosene, diesel, gasoline, and petroleum ether, were respectively mixed with deionized water in a ratio of (20 mL, V_oil:V_water = 1:1) to obtain six oil-water mixtures, which were poured from the upper pipe orifice of the device. After all the water was separated, wait for 10 s. For each sample, the test was repeated 3 times and the average value was taken. The separation efficiency (SE) and separation flux (SF) were calculated according to equations (1) and (2) respectively.

[0139] SE = V1 / V0 × 100% (1)

[0140] SF = V2 / st (2)

[0141] V0 and V1 represent the oil volumes (mL) before and after separation respectively; V2 represents the water volume (mL) separated through the separation material; s and t represent the effective separation area (cm 2 ) and the time (s) taken for oil-water separation respectively.

[0142] The test results are shown in Table 3 and Figure 3 、 4 as follows.

[0143] Table 3 Separation Efficiency and Separation Flux

[0144]

[0145]

[0146] As can be seen from Table 3, the SSM@SHPU@PA@PEI prepared in Examples 8 - 14 has relatively high separation efficiency and separation flux; in Comparative Example 4, due to the use of a single chain extender, no synergistic effect can be produced, and the increase in hydrogen bonds changes the phase separation structure of the material, resulting in poor mechanical properties of the material and a decrease in the stability of the coating, leading to a decline in the separation effect; in Comparative Example 5, due to the excessive addition of the chain extender, a large amount of unreacted substances affect the phase separation structure of the material, resulting in poor mechanical properties of the material and a decrease in the stability of the coating, leading to a decline in the separation effect; in Comparative Example 6, due to the use of a single chain extender, no synergistic effect can be produced, and the decrease in hydrogen bonds changes the phase separation structure of the material, resulting in poor mechanical properties of the material and a decrease in the stability of the coating, leading to a decline in the separation effect.

[0147] AsFigure 3 Shown as follows: the average separation efficiencies of SSM@SHPU, SSM@SHPU@PA, and SSM@SHPU@PA@PEI for six kinds of oils are 5.23%, 86.57%, and 98.53% respectively, as Figure 4 Shown as follows: the average separation fluxes of SSM@SHPU, SSM@SHPU@PA, and SSM@SHPU@PA@PEI for six kinds of oils are 19627.21 L / m 2 / h, 11436.75 L / m 2 / h, 11748.67 L / m 2 / h. Through Figure 3 , 4 It can be seen that through the chelation between phytic acid and iron ions, and through coordination, hydrogen bonding and other interactions, it firmly adheres to the surface of SHPU, and a coating with certain hydrophilicity is constructed on the surface of SHPU.

[0148] In the present invention, since phytic acid is negatively charged and polyethyleneimine is positively charged, it adheres to the surface of phytic acid through electrostatic interaction, constructing a roughness at the micro-nano scale and further increasing the hydrophilicity of the coating.

[0149] Experimental Example 5: Test on cyclic separation performance:

[0150] In order to test whether SSM@SHPU@PA@PEI can exert its self-healing performance in oil-water separation, a cyclic separation test was carried out.

[0151] Test grouping:

[0152] Non-self-healing group: SSM@SHPU@PA@PEI prepared in Example 8 was used;

[0153] Self-healing group 1: SSM@SHPU@PA@PEI prepared in Example 8 was used.

[0154] Self-healing group 2: The oil-water separation membrane prepared in Comparative Example 4 was used.

[0155] Test method:

[0156] An oil-water mixture composed of 10 ml of water and 10 ml of kerosene was used to carry out a cyclic separation test on the three groups of materials. Among them, during the test of Self-healing group 1 and Self-healing group 2, after every 4 cycles of separation, self-healing was carried out at 80 °C. After the repair was completed, the cyclic separation continued until 32 times; the non-self-healing group continued the cyclic separation until 32 times without self-healing treatment in the middle.

[0157] Test results:

[0158] As Figure 2As shown in the figure, it is the cyclic separation efficiency diagram of the self-healing oil-water separation membrane prepared in Example 8 for the kerosene / water mixture. In the 32-cycle separation test, it can be seen that the separation efficiency decline rates of the non-self-healing group and Self-healing Group 2 are significantly higher than that of Self-healing Group 1. After 32 cycles of separation, the separation efficiency of the non-self-healing group decreased by 2.14%, the separation efficiency of Self-healing Group 2 decreased by 4.60%, and the separation efficiency of Self-healing Group 1 only decreased by 0.87%. After 32 cycles of separation, the separation efficiency of the non-self-healing group SSM@SHPU@PA@PEI was 96.3%, and that of Self-healing Group 1 was 97.6%, which was 1.3% higher.

[0159] From the above experiments, it can be seen that for the self-healing oil-water separation membrane prepared in Example 8, due to the presence of two chain extenders, ODH and AD, the combination of the two plays a synergistic effect, endowing the material with self-healing ability while ensuring the mechanical properties of the coating material. The oil-water separation cycle effect of Self-healing Group 1 is significantly better than that of the non-self-healing group; for the oil-water separation membrane prepared in Comparative Example 4, due to the lack of the AD chain extender, no synergistic effect can be produced, so there is no self-healing effect. And the use of a single ODH chain extender leads to a decline in the mechanical properties of the coating material, making it difficult to withstand the multiple scouring of the oil-water mixture, and the oil-water separation cycle effect is poor.

[0160] The embodiments of the present application have been described above in conjunction with the accompanying drawings. However, the present application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all belong to the protection scope of the present application.

Claims

1. A method for preparing an oil-water separation membrane, characterized in that: The following steps are involved: ① Dilute the polyurea coating to 5-30wt%, apply it evenly on the substrate, and dry it; ② Place in 1-5wt% phytic acid aqueous solution for ultrasonic assembly for 10-30 minutes; ③ Add 1-5wt% FeCl3 aqueous solution with a volume of 1 / 2-1 / 10 of the phytic acid aqueous solution, continue ultrasonic assembly for 10-30 minutes, and then use deionized water to rinse off the unreacted chemicals; ④ Place in a 1-5wt% polyethyleneimine aqueous solution and stir for 1-5h, rinse off unreacted chemicals with deionized water, and dry; The preparation method of the polyurea coating comprises the following steps: ① Preparation of polyurea prepolymer: Add 20 ml of dimethylformamide into a three-necked flask as a solvent, then add 10 mmol of polyetheramine and 20 mmol of isophorone diisocyanate in sequence, and finally add 0.13 g of dibutyltin dilaurate as a catalyst; stir in a water bath at 30°C for 1 hour to obtain a polyurea prepolymer with a long chain structure terminated with an isocyanate group; ② Add 30 ml of dimethylformamide to 41.93 g of polyurea prepolymer to reduce its viscosity, then add 10 mmol of chain extender, and stir in a water bath at 50° C. for 3 h to obtain a polyurea coating; The chain extender is 4,4'-diaminodiphenyl disulfide and oxalyl dihydrazide, and the molar ratio of the 4,4'-diaminodiphenyl disulfide to 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. Application of the oil-water separation membrane as claimed in claim 2 in the field of oil-water separation.

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