Super-hydrophobic material, preparation method and application thereof

Abstract

The application discloses a kind of super-hydrophobic material and its preparation method and application, belong to functional material field.The application first uses bis (3-amino propyl) end-capped poly (dimethylsiloxane), diisocyanate compound, dissolves in organic solvent, carries out prepolymerization, then slowly adds the polyamino compound of tertiary amino group, carries out addition polymerization reaction, obtains pH response type polymer solution;Afterwards, hydrophobic nanoparticles are added in pH response type polymer solution, and mixed solution is obtained;Finally, the mixed solution is used to treat cellulose fiber material, and a pH-responsive and self-repairing super-hydrophobic material is obtained.The application utilizes the protonation and deprotonation of pH-responsive polymer in different pH environments to provide super-hydrophobicity and underwater super-oleophobicity for the surface of super-hydrophobic material, and at the same time, the pH-responsive super-hydrophobic material has the properties of organic solvent resistance, abrasion resistance, ultraviolet resistance, heat resistance, etc.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of super-hydrophobic material and its preparation method and application, belong to functional material field. BACKGROUND

[0002] Super-hydrophobic refers to the wetting state of the contact angle of water on the surface greater than 150°, when the contact angle of water on the surface of material is more than 150°, it is called super-hydrophobic surface. There are many super-hydrophobic phenomena in nature, such as the surface of lotus leaf, the wings of butterfly and other insects, water droplets can freely roll on super-hydrophobic surface, and the pollutants attached to the super-hydrophobic surface are removed, which has self-cleaning effect. Super-hydrophobic surface benefits from its special surface performance, and is widely used in antifouling, self-cleaning, ice prevention, corrosion prevention, water-oil separation and other fields. Inspired by natural lotus leaf, researchers have realized that the coexistence of wax and microscale is the key to realizing super-hydrophobic surface, that is, materials with low surface energy and micro-nano structure can be used to create super-hydrophobic surface. Single wettability limits the ability of the material to handle complex practical scenarios, so it is necessary to design and prepare materials with fast adjustable wettability.

[0003] Cellulose fiber material has the characteristics of low price, soft hand feeling, good moisture absorption and air permeability, and is the most widely used natural fiber fabric. Because the cellulose surface contains a large number of hydroxyl groups, its hydrophilicity is strong, easy to dye, and also brings many problems, such as difficult to clean after being stained, easy to mildew, breeding bacteria, etc. These problems greatly limit the application of cellulose fiber material. Attaching a layer of super-hydrophobic coating to the surface of cellulose fiber material can give the cellulose fiber material cotton fabric self-cleaning effect, greatly improving the problems of easy pollution and easy mildew, but single wettability limits the ability of the material to handle complex practical scenarios.

[0004] At present, many literatures mention the preparation of pH-responsive super-hydrophobic materials;

[0005] For example: CN112981973A discloses a preparation method of pH-responsive super-hydrophobic material, which is to mix super-hydrophobic silicon dioxide and acrylate copolymer uniformly and then spray it onto the fabric substrate to obtain a pH-responsive super-hydrophobic coating. The super-hydrophobic material realizes super-hydrophobic to super-oleophilic conversion within a certain pH range, has good environmental responsiveness, good wear resistance, strong adhesion, good adaptability to substrate, overcomes the weaknesses of traditional water-oil separation methods such as complex operation and time-consuming, and simplifies the post-processing process of super-hydrophobic-super-oleophilic material from the perspective of separating water phase, and the preparation process is simple and easy to control.

[0006] CN113463402A discloses a preparation method of a pH-responsive super-hydrophobic-hydrophilic reversible material surface, which is first prepared into a microcapsule, then a fluorine-containing substance is added to form a pH-responsive microcapsule, and finally used to form a pH-responsive super-hydrophobic-hydrophilic reversible material surface on the material surface; the reversible conversion from super-hydrophobicity to hydrophilicity can be realized, and the conversion times can reach dozens of times, having strong durability and ability to resist damage from external environment; however, the droplet with pH = 1 is completely absorbed on the hydrophobic surface only after 120 s, and the response speed is slow.

[0007] Moreover, pyridine, carboxyl and tertiary amine group are typical pH-responsive functional groups. Carboxyl can be protonated at low pH value, showing relatively hydrophobic property, while at high pH value, it appears in the form of carboxylate anion, having relatively hydrophilic property, but compared with tertiary amine group, carboxyl is easy to participate in esterification, amidation and other chemical reactions, affecting its stability in application. The protonation and deprotonation process of pyridine is not as significant as that of tertiary amine group, resulting in weak responsiveness and slow response speed, and introducing pyridine functional group into the material usually needs multiple-step chemical reactions, increasing the complexity and cost of material synthesis.

[0008] It can be seen that the preparation process of conventional pH-responsive super-hydrophobic material is complex, the reaction period is long, the response speed is slow, the service life is short, and the material does not have self-repairing performance; therefore, it is necessary to prepare a super-hydrophobic material with fast response, adjustable wettability, self-repairing and good durability. SUMMARY

[0009] [TECHNICAL PROBLEM]

[0010] The preparation process of conventional pH-responsive super-hydrophobic material is complex, the reaction period is long, the response speed is slow, the service life is short, and the material does not have self-repairing performance.

[0011] [TECHNICAL SCHEME]

[0012] In order to solve the above problems, the present application first dissolves a diisocyanate compound and bis(3-aminopropyl) terminated poly(dimethylsiloxane) in an organic solvent to perform prepolymerization, then slowly adds a polyamino compound containing a tertiary amine group to perform addition polymerization reaction, to obtain a pH-responsive polymer solution; then, hydrophobic nanoparticles are added to the pH-responsive polymer solution to obtain a mixed solution; finally, the mixed solution is used to treat cellulose fiber material to obtain a pH-responsive and self-repairing super-hydrophobic material. The present application utilizes the protonation and deprotonation of pH-responsive polymer in different pH environments to provide super-hydrophobicity and underwater super-oleophobicity on the surface of the super-hydrophobic material, and at the same time, enables the pH-responsive super-hydrophobic material to have properties such as resistance to organic solvents, resistance to abrasion, resistance to ultraviolet rays, resistance to heat, etc.

[0013] The first object of the present application is to provide a method for preparing a pH-responsive polymer solution, comprising the following steps:

[0014] The bis(3-aminopropyl)-terminated poly(dimethylsiloxane), the diisocyanate compound and the tertiary amino-containing polyamino compound are dissolved in an organic solvent, pre-polymerization is carried out, and then the tertiary amino-containing polyamino compound is slowly added to carry out addition polymerization to obtain the pH-responsive polymer solution.

[0015] The tertiary amino-containing polyamino compound is one or both of tris(2-aminoethyl)amine and laurylamine dipropylene diamine.

[0016] The molar ratio of the bis(3-aminopropyl)-terminated poly(dimethylsiloxane), the diisocyanate compound and the tertiary amino-containing polyamino compound is 1-4:2-14:2-10.

[0017] In an embodiment of the present application, the CAS code of the bis(3-aminopropyl)-terminated poly(dimethylsiloxane) is 106214-84-0.

[0018] In an embodiment of the present application, the diisocyanate compound is one or more of isophorone diisocyanate, toluene diisocyanate and 1,6-hexane diisocyanate.

[0019] In an embodiment of the present application, the molar ratio of the bis(3-aminopropyl)-terminated poly(dimethylsiloxane), the diisocyanate compound and the tertiary amino-containing polyamino compound is 3:11:7.

[0020] In an embodiment of the present application, the pre-polymerization is carried out at 20-50°C and 300-500 rpm for 1-10 h, and nitrogen blowing is required for more than 20 min before pre-polymerization.

[0021] In an embodiment of the present application, the organic solvent is one or more of tetrahydrofuran, chloroform and acetone.

[0022] In an embodiment of the present application, the addition polymerization reaction can be carried out without adding a catalyst.

[0023] In an embodiment of the present application, the addition polymerization reaction is carried out at 20-50°C and 300-500 rpm for 1-10 h.

[0024] The second object of the present application is the pH-responsive polymer solution prepared by the method of the present application.

[0025] In an embodiment of the present application, the mass fraction of the pH-responsive polymer in the pH-responsive polymer solution is 5-25%.

[0026] In one embodiment of the present invention, the mass fraction of the pH responsive polymer in the pH responsive polymer solution is the percentage of the sum of the masses of the bis(3-aminopropyl)-terminated poly(dimethylsiloxane), the diisocyanate compound and the polyamino compound containing a tertiary amino group in the mass of the entire solution.

[0027] A third object of the present invention is to provide a method for preparing a pH-responsive and self-healing superhydrophobic material, comprising the following steps:

[0028] Hydrophobic nanoparticles are added to a pH-responsive polymer solution and mixed evenly to obtain a mixed solution; then, a cellulose fiber material is immersed in the mixed solution, taken out, and solidified to obtain a pH-responsive and self-repairing superhydrophobic material.

[0029] In one embodiment of the present invention, the hydrophobic nanoparticles are one or more of titanium dioxide, silicon dioxide, and carbon black nanoparticles; and the particle size is 1-200 nm.

[0030] In one embodiment of the present invention, the mass concentration of the hydrophobic nanoparticles in the pH-responsive polymer solution is 10-40%.

[0031] In one embodiment of the present invention, the uniform mixing is ultrasonic mixing; and the ultrasonic treatment is ultrasonic treatment at 200-400W for 5-20min.

[0032] In one embodiment of the present invention, the cellulose fiber material is one or more of cotton fabric, paper, viscose fabric, modal fabric or lyocell fabric; it can also be a blended fabric, such as a blended fabric of cotton, viscose, modal, lyocell, etc.

[0033] In one embodiment of the present invention, the cellulose fiber material needs to be pretreated before use, specifically:

[0034] The cellulose fiber material is ultrasonically treated with deionized water and ethanol in sequence, and washed in each solvent for 20 to 30 minutes. After washing, the cellulose fiber material is dried to obtain a pretreated cellulose fiber material.

[0035] In one embodiment of the present invention, the immersion is carried out at 20-30° C., and may be accompanied by ultrasound, wherein the ultrasound is carried out at 200-400 W for 5-20 min.

[0036] In one embodiment of the present invention, the curing is performed at 50-150° C. for 10-60 min.

[0037] The fourth object of the present invention is a pH-responsive and self-healing superhydrophobic material prepared by the method described in the present invention.

[0038] A fifth object of the present application is the application of the pH-responsive polymer solution, the pH-responsive and self-repairing super-hydrophobic material described in the present application in the field of anti-fouling, self-cleaning, anti-icing, anti-corrosion or water-oil separation.

[0039] A sixth object of the present application is to provide a method for water-oil separation, which employs the pH-responsive and self-repairing super-hydrophobic material described in the present application.

[0040] A seventh object of the present application is to provide a method for improving the pH-responsive, super-hydrophobic and self-repairing properties of cotton fabric, which employs the pH-responsive and self-repairing super-hydrophobic material described in the present application.

[0041] An eighth object of the present application is to provide a method for quickly realizing the reversible switching of the super-hydrophobic-hydrophilic-super-hydrophobic properties of the surface of cotton fabric, which employs the pH-responsive and self-repairing super-hydrophobic material described in the present application.

[0042] [Advantages]

[0043] (1) The present application introduces bis(3-aminopropyl)-terminated poly(dimethylsiloxane) and a tertiary amino-containing polyamino compound into the same molecule to obtain a pH-responsive super-hydrophobic polymer; thus, the polymer has both pH-responsive properties and low surface energy; wherein the tertiary amine group structure can change the surface wettability by inducing protonation and deprotonation through changing the pH.

[0044] (2) The present application combines the surface texture and structural characteristics of hydrophobic nanoparticles and cellulose fiber materials and their weaving methods to form a micro-nano multi-level structure, further enhancing the hydrophobic properties and response properties of the coating.

[0045] (3) The method for preparing the super-hydrophobic cellulose fiber material of the present application can prepare a super-hydrophobic cellulose fiber material with properties such as organic solvent resistance, abrasion resistance, ultraviolet resistance, and heat resistance without the need for complex equipment and complex processes.

[0046] (4) After the pH-responsive super-hydrophobic finishing of the cellulose fiber material, the hydrophobic nanoparticles provide roughness, and bis(3-aminopropyl)-terminated poly(dimethylsiloxane) reduces the surface energy of the cellulose fiber material; the introduction of a tertiary amino-containing polyamino compound provides pH-responsive properties through protonation and deprotonation, thereby realizing the rapid switching of wettability, and finally preparing a pH-responsive super-hydrophobic cellulose fiber material with properties such as organic solvent resistance, abrasion resistance, ultraviolet resistance, and heat resistance. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1Reaction mechanism and infrared spectrum of the prepolymer (PDMS-IPDI) before reaction and the product (pH-PU) in the pH-responsive polymer in Example 1.

[0048] Figure 2 SEM images of the original cotton fabric (a), the hydrophobic cotton fabric prepared in Comparative Example 3 (b), and the super-hydrophobic cotton fabric prepared in Example 4 (c: 10 μm; d: 1 μm).

[0049] Figure 3 FTIR spectra of the original cotton fabric, the pH-responsive polymer, the super-hydrophobic cotton fabric prepared in Example 4, XPS spectra and C1s fitting curves of the super-hydrophobic cotton fabric prepared in Example 4; wherein (a) is the FTIR spectra of the original cotton fabric, the pH-responsive polymer, and the super-hydrophobic cotton fabric prepared in Example 4; (b) is the XPS spectra of the original cotton fabric and the super-hydrophobic cotton fabric prepared in Example 4; (c) is the C1s fitting curve of the original cotton fabric; and (d) is the C1s fitting curve of the super-hydrophobic cotton fabric prepared in Example 4.

[0050] Figure 4 Schematic diagrams, WCA, and SEM images of the super-hydrophobic cotton fabric prepared in Example 4 after the Martindale abrasion test, the adhesive tape peeling test, and the ultrasonic test; wherein (1) is the schematic diagram, WCA, and SEM image (a) of the super-hydrophobic cotton fabric prepared in Example 4 after the Martindale abrasion test; (2) is the schematic diagram, WCA, and SEM image (b) of the super-hydrophobic cotton fabric prepared in Example 4 after the adhesive tape peeling test; and (3) is the schematic diagram, WCA, and SEM image (c) of the super-hydrophobic cotton fabric prepared in Example 4 after the ultrasonic test.

[0051] Figure 5 Chemical stability test of the super-hydrophobic cotton fabric prepared in Example 4; wherein (a) is the contact angle-time curve of the super-hydrophobic cotton fabric prepared in Example 4 in a 150℃ oven; (b) is the contact angle-time curve of the super-hydrophobic cotton fabric prepared in Example 4 after being placed in a weatherometer for treatment; (c) is the contact angle data graph of the super-hydrophobic cotton fabric prepared in Example 4 after being immersed in solutions with different pH values for 72 hours; and (d) is the contact angle data graph of the super-hydrophobic cotton fabric prepared in Example 4 after being immersed in organic solvents (tetrahydrofuran, ethanol, n-hexane, acetone, toluene) for 72 hours.

[0052] Figure 6 Self-repairing performance test of the super-hydrophobic cotton fabric prepared in Example 4; wherein (a) is the test result of 5 cycles of plasma treatment-thermal repair; and (b) is the self-healing mechanism of the super-hydrophobic cotton fabric.

[0053] Figure 7Application of the superhydrophobic cotton fabric prepared in Example 4 in the field of oil-water separation; wherein (a) is the oil removal model; (b) is the water removal model; (c) is the oil removal model after 5 cycles; (d) is the water removal model after 5 cycles. DETAILED DESCRIPTION

[0054] The following describes the preferred embodiments of the present application, and it should be understood that the embodiments are for better explaining the present application, and are not used to limit the present application.

[0055] Test method:

[0056] 1. Superhydrophobic performance test:

[0057] The static contact angle of the superhydrophobic cotton fabric was tested by measuring 5 μL of water droplets at three different positions of the fabric using a DSA-25 contact angle measuring instrument, and then the average value was obtained.

[0058] 2. Rubbing resistance test:

[0059] According to GB / T 21196.4-2007 "Textiles - Determination of the abrasion resistance of fabrics by the Martindale method - Part 4: Assessment of appearance change", a YG(B)401T Martindale abrasion tester was used to test the abrasion resistance of the modified cotton fabric.

[0060] 3. Tape peeling test:

[0061] For the tape peeling test, a 200g weight was placed on the tape (3M; Scotch Magic Tape 810) to apply pressure to the tape, so that the tape could be in close and uniform contact with the superhydrophobic cotton fabric. Then, the tape was carefully removed, and the contact angle of the superhydrophobic cotton fabric was measured after every 20 scratches.

[0062] 4. Ultrasonic test:

[0063] The superhydrophobic cotton fabric was immersed in ethanol at room temperature and treated with ultrasonic waves at a frequency of 28 kHz and a power of 300 W for 240 min. The contact angle was recorded every 60 min.

[0064] 5. High temperature resistance test:

[0065] The superhydrophobic cotton fabric was placed at 150°C for 120h, and the contact angle was measured every 20h.

[0066] 6. Sunlight weathering test:

[0067] According to the test method of GB / T 8427-2009 "Textiles - Colour fastness tests - Colour fastness to artificial light: Xenon arc", a xenon arc lamp was used as the light source, and the superhydrophobic cotton fabric was exposed to sunlight for 60h, and the contact angle change was recorded every 10 hours.

[0068] 7. Organic solvent resistance test:

[0069] The superhydrophobic cotton fabric was immersed in different organic solvents (acetone, ethanol, toluene, n-hexane) for 72 hours. After immersion, the fabric was washed with water several times and dried at 80 °C for 30 minutes, and then the contact angle change was tested.

[0070] 8. Self-healing performance test:

[0071] The superhydrophobic cotton fabric was treated with a plasma cleaning machine (SUNJUNE PLASMA VP-R3, China) under high vacuum conditions for 30 seconds to achieve a superhydrophilic state. Subsequently, the plasma-treated sample was healed under ambient conditions or in an oven at 120 °C to restore its superhydrophobicity, and the contact angle was measured.

[0072] Raw materials used in the examples:

[0073] Bis(3-aminopropyl) terminated poly(dimethylsiloxane): CAS code 106214-84-0;

[0074] Isophorone diisocyanate: CAS code 4098-71-9;

[0075] Laurylamine dipropylene diamine: CAS code 2372-82-9;

[0076] Silicon dioxide nanoparticles: particle size 16 nm, purchased from Shandong Yousuo Chemical Technology Co., Ltd;

[0077] Cotton fabric: twill, warp and weft yarn density both 18.4 tex, warp and weft density respectively 250 / 10 cm and 150 / 10 cm.

[0078] The cotton fabric used in the examples and comparative examples was pretreated, which was ultrasonically treated with deionized water and ethanol in sequence, and washed in each solvent for 20 minutes. After washing, it was taken out and dried in an oven at 80 °C.

[0079] Example 1

[0080] A method for preparing a pH-responsive polymer solution, comprising the following steps:

[0081] 1.5 g of bis(3-aminopropyl) terminated poly(dimethylsiloxane) (NH2-PDMS-NH2) and 0.489 g of isophorone diisocyanate (IPDI) were dissolved in 13.651 g of tetrahydrofuran, and after purging with nitrogen for 30 min, pre-polymerization was carried out at 25°C and 500 rpm for 2 h, then 0.42 g of laurylamine dipropylenediamine was slowly added dropwise, and addition polymerization was carried out at 25°C and 500 rpm for 4 h to obtain a pH-responsive polymer solution; wherein the mass fraction of the pH-responsive polymer in the pH-responsive polymer solution is 15%; the molar ratio of bis(3-aminopropyl) terminated poly(dimethylsiloxane), isophorone diisocyanate, and laurylamine dipropylenediamine is 3:11:7.

[0082] The reaction mechanism diagram and infrared spectrum are as follows Figure 1 .

[0083] From Figure 1 it can be seen that the appearance of the urea bond group absorption peak at 1700 cm -1 around confirms the successful synthesis of the PDMS-IPDI prepolymer; after reacting laurylamine dipropylenediamine with the PDMS-IPDI prepolymer, the characteristic peak of the isocyanate group at 2250 cm -1 around basically disappears, indicating that laurylamine dipropylenediamine has successfully reacted with the prepolymer, and these evidences prove that the pH-PU has been successfully synthesized. 800 cm -1 is the rocking vibration absorption peak of Si-CH3, 1000 cm -1 is the stretching peak of siloxane; 1260 cm -1 is the symmetric bending absorption peak of Si-CH3, and 3000 cm -1 around is the stretching vibration characteristic peak of methyl and methylene.

[0084] Example 2

[0085] A method for preparing a pH-responsive and self-repairing super-hydrophobic material, comprising the following steps:

[0086] 0.1 g of silica nanoparticles was added to 4 g of the pH-responsive polymer solution of Example 1, and ultrasonic treatment was carried out at a frequency of 28 kHz and a power of 300 W for 10 min to uniformly mix them, to obtain a mixed solution;

[0087] The cotton fabric was immersed in the mixed solution at 25°C, while being accompanied by ultrasonic treatment at a frequency of 28 kHz and a power of 300 W for 5 min, and then taken out and heat cured at 120°C for 30 min to obtain a pH-responsive and self-repairing super-hydrophobic material.

[0088] Example 3

[0089] Adjust the amount of silica nanoparticles in Example 2 to 0.2g, and keep the same as Example 2, to obtain the super-hydrophobic material.

[0090] Example 4

[0091] Adjust the amount of silica nanoparticles in Example 2 to 0.3g, and keep the same as Example 2, to obtain the super-hydrophobic material.

[0092] Example 5

[0093] Adjust the amount of silica nanoparticles in Example 2 to 0.4g, and keep the same as Example 2, to obtain the super-hydrophobic material.

[0094] Example 6

[0095] Adjust the preparation method of pH-responsive polymer solution in Example 2 as follows:

[0096] Dissolve 1.5g of bis(3-aminopropyl)-terminated poly(dimethylsiloxane) (NH2-PDMS-NH2) and 0.60g of isophorone diisocyanate (IPDI) in 13.06g of tetrahydrofuran, and after purging with nitrogen for 30min, pre-polymerize at 25℃, 500rpm for 2h, then slowly add 0.205g of tris(2-aminoethyl)amine, and addition polymerization reaction occurs at 25℃, 500rpm for 4h, to obtain the pH-responsive polymer solution; wherein the mass fraction of pH-responsive polymer in the pH-responsive polymer solution is 15%; the molar ratio of bis(3-aminopropyl)-terminated poly(dimethylsiloxane), isophorone diisocyanate, and tris(2-aminoethyl)amine is 3:13.5:7;

[0097] Keep the same as Example 2, to obtain the super-hydrophobic material.

[0098] Example 7

[0099] Adjust the amount of tetrahydrofuran in Example 1 to 21.681g, and keep the same as Example 1, to obtain the pH-responsive polymer solution with a mass fraction of pH-responsive polymer of 10%;

[0100] Adjust the mass fraction of pH-responsive polymer in the pH-responsive polymer solution in Example 2 to 10%, and keep the same as Example 2, to obtain the super-hydrophobic material.

[0101] Example 8

[0102] Adjust the amount of tetrahydrofuran in Example 1 to 9.636g, and keep the same as Example 1, to obtain the pH-responsive polymer solution with a mass fraction of pH-responsive polymer of 20%;

[0103] Adjust the mass fraction of the pH-responsive polymer in the pH-responsive polymer solution in Example 2 to 20%, and keep the rest the same as in Example 2 to obtain the super-hydrophobic material.

[0104] Comparative Example 1

[0105] Adjust the preparation method of the pH-responsive polymer solution in Example 2 as follows:

[0106] Dissolve 0.5 g of bis(3-aminopropyl)-terminated poly(dimethylsiloxane), 0.489 g of isophorone diisocyanate in 8.66 g of tetrahydrofuran, and then pre-polymerize at 25°C and 500 rpm for 2 h. Then slowly add 0.54 g of laurylamine dipropylene diamine to the mixture, and then carry out addition polymerization at 25°C and 500 rpm for 4 h to obtain a pH-responsive polymer solution. The mass fraction of the pH-responsive polymer in the pH-responsive polymer solution is 15%. The molar ratio of bis(3-aminopropyl)-terminated poly(dimethylsiloxane), isophorone diisocyanate, and laurylamine dipropylene diamine is 1:11:9.

[0107] Meanwhile, adjust the amount of the silica nanoparticles to 0 g, i.e., omit the addition of the silica nanoparticles, and keep the rest the same as in Example 2 to obtain the super-hydrophobic material.

[0108] Comparative Example 2

[0109] Adjust the preparation method of the pH-responsive polymer solution in Example 2 as follows:

[0110] Dissolve 1.0 g of bis(3-aminopropyl)-terminated poly(dimethylsiloxane), 0.489 g of isophorone diisocyanate in 11.16 g of tetrahydrofuran, and then pre-polymerize at 25°C and 500 rpm for 2 h. Then slowly add 0.48 g of laurylamine dipropylene diamine to the mixture, and then carry out addition polymerization at 25°C and 500 rpm for 4 h to obtain a pH-responsive polymer solution. The molar ratio of bis(3-aminopropyl)-terminated poly(dimethylsiloxane), isophorone diisocyanate, and laurylamine dipropylene diamine is 2:11:8.

[0111] Meanwhile, adjust the amount of the silica nanoparticles to 0 g, i.e., omit the addition of the silica nanoparticles, and keep the rest the same as in Example 2 to obtain the super-hydrophobic material.

[0112] Comparative Example 3

[0113] Adjust the preparation method of the pH-responsive polymer solution in Example 2 as follows:

[0114] 1.5 g of bis(3-aminopropyl) terminated poly(dimethylsiloxane), 0.489 g of isophorone diisocyanate were dissolved in 8.66 g of tetrahydrofuran, after purging with nitrogen for 30 min, pre-polymerization was carried out at 25℃, 500 rpm for 2 h, then 0.42 g of laurylamine dipropylenediamine was slowly added and dropwise, and addition polymerization reaction was carried out at 25℃, 500 rpm for 4 h to obtain a pH-responsive polymer solution; wherein the molar ratio of bis(3-aminopropyl) terminated poly(dimethylsiloxane), isophorone diisocyanate, laurylamine dipropylenediamine is 3:11:7;

[0115] Meanwhile, the amount of silicon dioxide nanoparticles was adjusted to 0 g, that is, the addition of silicon dioxide nanoparticles was omitted, and the other conditions were the same as in Example 2 to obtain a super-hydrophobic material.

[0116] Comparative Example 4

[0117] The preparation method of the pH-responsive polymer solution in Example 2 was adjusted as follows:

[0118] 2.0 g of bis(3-aminopropyl) terminated poly(dimethylsiloxane), 0.489 g of isophorone diisocyanate were dissolved in 8.66 g of tetrahydrofuran, after purging with nitrogen for 30 min, pre-polymerization was carried out at 25℃, 500 rpm for 2 h, then 0.36 g of laurylamine dipropylenediamine was slowly added and dropwise, and addition polymerization reaction was carried out at 25℃, 500 rpm for 4 h to obtain a pH-responsive polymer solution; wherein the molar ratio of bis(3-aminopropyl) terminated poly(dimethylsiloxane), isophorone diisocyanate, laurylamine dipropylenediamine is 4:11:6;

[0119] Meanwhile, the amount of silicon dioxide nanoparticles was adjusted to 0 g, that is, the addition of silicon dioxide nanoparticles was omitted, and the other conditions were the same as in Example 2 to obtain a super-hydrophobic material.

[0120] Comparative Example 5

[0121] The preparation method of the pH-responsive polymer solution in Example 2 was adjusted as follows:

[0122] 2.5 g of bis(3-aminopropyl) terminated poly(dimethylsiloxane), 0.489 g of isophorone diisocyanate were dissolved in 8.66 g of tetrahydrofuran, after purging with nitrogen for 30 min, pre-polymerization was carried out at 25℃, 500 rpm for 2 h, then 0.30 g of laurylamine dipropylenediamine was slowly added and dropwise, and addition polymerization reaction was carried out at 25℃, 500 rpm for 4 h to obtain a pH-responsive polymer solution; wherein the molar ratio of bis(3-aminopropyl) terminated poly(dimethylsiloxane), isophorone diisocyanate, laurylamine dipropylenediamine is 5:11:5

[0123] Meanwhile, the amount of the silica nanoparticles is adjusted to 0 g, i.e., the addition of the silica nanoparticles is omitted, and the other conditions are the same as those in Example 2, to obtain the super-hydrophobic material.

[0124] The obtained super-hydrophobic material is subjected to performance testing, and the testing results are as follows:

[0125] Table 1

[0126]

[0127] Note: The wetting switching time is recorded by using a contact angle tester to record a video, and the time for the water droplet to completely wet the fabric is observed from the video.

[0128] As can be seen from Table 1, the hydrophobic nanoparticles can improve the surface roughness, which is crucial for achieving super-hydrophobicity. When the content of the hydrophobic nanoparticles is low, most of the hydrophobic nanoparticles may be coated by the responsive polymer, so that the best effect cannot be achieved. When the content of the hydrophobic nanoparticles is high, too much silica destroys the best balance state of the polymer, so that although the initial contact angle is relatively high, the mechanical durability decreases. In Example 4, the content of the silica nanoparticles is the most appropriate, which can improve the surface roughness and has the best mechanical durability. Further stability research is conducted on Example 4.

[0129] Figure 3 Fourier transform infrared spectrograms of a raw cotton fabric, a pH-responsive polymer, a super-hydrophobic cotton fabric prepared in Example 4, an X-ray photoelectron spectrogram of the super-hydrophobic cotton fabric prepared in Example 4, and a C1s fitting curve diagram of the super-hydrophobic cotton fabric prepared in Example 4; wherein (a) is the Fourier transform infrared spectrograms of the raw cotton fabric, the pH-responsive polymer, and the super-hydrophobic cotton fabric prepared in Example 4; (b) is the X-ray photoelectron spectrogram of the raw cotton fabric and the super-hydrophobic cotton fabric prepared in Example 4; (c) is the C1s fitting curve diagram of the raw cotton fabric; and (d) is the C1s fitting curve diagram of the super-hydrophobic cotton fabric prepared in Example 4. As can be seen from (a), compared with the raw cotton, the super-hydrophobic cotton fabric has a new absorption peak at 800 cm Figure 3 -1 which is a rocking vibration absorption peak of Si-CH3, and an absorption peak of Si-CH3 at 1260 cm -1 , and an absorption peak of the urea bond group at about 1700 cm -1 , and the stretching vibration characteristic peaks of the methyl and methylene groups at about 3000 cm -1 , which are obviously larger, are caused by the combination of the pH-responsive polymer and the cotton fabric. As can be seen from (b), compared with the raw cotton fabric, the super-hydrophobic cotton fabric newly detects N and Si elements; and as can be seen from (c) and (d), compared with the raw cotton fabric, the super-hydrophobic cotton fabric has a new absorption peak at 102.7 eV, which is the binding energy of Si, and a new absorption peak at 399.8 eV, which is the binding energy of N. Figure 3 Figure 3 ​​As can be seen from (c) and (d), the C-H / C-C bond is at 284.8 eV, the C-O-C bond is at 286.42 eV, and the C=O bond is at 288.09 eV; the C1s spectrum of the original cotton fabric is fitted with three peaks, while the C1s spectrum of the super-hydrophobic cotton fabric is fitted with five peaks, and two new peaks of C-N bond at 286.0 eV and C-Si bond at 283.9 eV are detected, which belong to the pH-responsive polymer.

[0130] Figure 4 Schematic diagrams, water contact angles (WCAs) and SEM images of the super-hydrophobic cotton fabric prepared in Example 4 after Martindale abrasion test, tape peeling and ultrasonic test; wherein (1) is the schematic diagram, WCA and SEM image (a) of the super-hydrophobic cotton fabric prepared in Example 4 after Martindale abrasion test; (2) is the schematic diagram, WCA and SEM image (b) of the super-hydrophobic cotton fabric prepared in Example 4 after tape peeling; (3) is the schematic diagram, WCA and SEM image (c) of the super-hydrophobic cotton fabric prepared in Example 4 after ultrasonic test. As can be seen from (1), (2) and (3), the contact angle of the super-hydrophobic cotton fabric prepared in Example 4 gradually decreases with the experiment, but it does not lose super-hydrophobicity after 700 times of Martindale abrasion test, 100 times of tape peeling and 6 hours of ultrasonic test, respectively. Figure 4 As can be seen from (c) and (d), the C-H / C-C bond is at 284.8 eV, the C-O-C bond is at 286.42 eV, and the C=O bond is at 288.09 eV; the C1s spectrum of the original cotton fabric is fitted with three peaks, while the C1s spectrum of the super-hydrophobic cotton fabric is fitted with five peaks, and two new peaks of C-N bond at 286.0 eV and C-Si bond at 283.9 eV are detected, which belong to the pH-responsive polymer.

[0131] Figure 5 Chemical stability test of the super-hydrophobic cotton fabric prepared in Example 4; wherein (a) is the contact angle-time curve of the super-hydrophobic cotton fabric prepared in Example 4 in a 150℃ oven; (b) is the contact angle-time curve of the super-hydrophobic cotton fabric prepared in Example 4 after being placed in a weatherometer for treatment; (c) is the contact angle data graph of the super-hydrophobic cotton fabric prepared in Example 4 after being immersed in solutions with different pH values for 72 hours; (d) is the contact angle data graph of the super-hydrophobic cotton fabric prepared in Example 4 after being immersed in organic solvents (tetrahydrofuran, ethanol, n-hexane, acetone, toluene) for 72 hours. As can be seen from (a), (b), (c) and (d), the contact angle of the super-hydrophobic cotton fabric prepared in Example 4 is not affected by long-term high-temperature environment, and the contact angle almost does not change. Figure 5 As can be seen from (a), the contact angle of the super-hydrophobic cotton fabric is not affected by long-term high-temperature environment, and the contact angle almost does not change. Figure 5 As can be seen from (b), the contact angle of the super-hydrophobic cotton fabric is not affected by long-term weathering test, and the contact angle does not change significantly. Figure 5 As can be seen from (c), the contact angle of the super-hydrophobic cotton fabric does not change significantly after being immersed in acidic solution, but the contact angle of the cotton fabric immersed in strong alkaline solution decreases, but still maintains hydrophobicity. Figure 5 As can be seen from (d), the contact angle of the super-hydrophobic cotton fabric does not change significantly after being immersed in organic solvents.

[0132] Figure 6 Self-repairing performance test of the super-hydrophobic cotton fabric prepared in Example 4.Figure 6 It can be seen that after 30 s of plasma treatment, the superhydrophobic cotton fabric is converted from superhydrophobic to superhydrophilic, and the WCA is directly reduced to 0°. After the superhydrophobic coating is damaged, the coating can restore its superhydrophobicity after heating at 120 °C for 30 min, and the WCA can reach 157.0 ± 0.5°. Even after 5 cycles of plasma treatment-thermal repair, the superhydrophobic cotton fabric can still restore superhydrophobicity. During the plasma treatment, the hydrophobic PDMS chains on the surface of the coating are damaged, and at the same time, hydrophilic oxygen-containing groups are introduced onto the surface of the coating. After high-temperature treatment, the hydrophobic PDMS chains migrate to the damaged area and cover the hydrophilic groups, realizing the self-repairing process.

[0133] Example 9 Application of oil-water separation

[0134] To further demonstrate the application of superhydrophobic cotton fabric in oil-water separation, because of its wetting switching performance, various oils mixed with water can be separated using oil removal and water removal methods. In this case, gravity is the only driving force.

[0135] When separating water and heavy oil (oil removal model), dichloroethane is taken as an example.

[0136] A mixture of dichloroethane and water is slowly poured into a separation device with a superhydrophobic cotton fabric as a separation membrane. Figure 7 In a), due to the superhydrophobicity and superoleophilicity of the coated fabric, water remains on the fabric, and dichloroethane can permeate the fabric to achieve separation.

[0137] When separating a mixture of light oil represented by n-hexane and water (water removal model), the superhydrophobic cotton fabric can be treated in advance with an acidic aqueous solution (pH = 2). After treatment, a mixture of n-hexane and water is slowly poured into a separation device with a superhydrophobic cotton fabric as a separation membrane. Water can quickly pass through the superhydrophobic cotton fabric, while oil cannot pass through the superhydrophobic cotton fabric, achieving separation of the light oil / water mixture (b in Figure 7 ).

[0138] As shown in c, d in Figure 7 , even after five cycles, both the oil removal and water removal models maintain excellent separation efficiency, about 97.4 ± 0.2% and 97.8 ± 0.3%, respectively. Although the permeation flux has decreased slightly compared to the initial level, it is still very high, 13981.53 ± 1346.84 and 11572.90 ± 466.46 L·m -2 ·h -1 .

[0139] In summary, the hydrophobic property of the super-hydrophobic cotton fabric prepared by the application decreases with the increase of the friction times, the adhesive tape peeling times and the ultrasonic testing time, but the super-hydrophobic property is not lost after 700 times of Martin Dale friction test, 100 times of adhesive tape peeling and 6 hours of ultrasonic test; only the strong alkali solution has a certain influence on the super-hydrophobic property of the super-hydrophobic cotton fabric, the strong acid solution and the organic solvent have no influence on the super-hydrophobic property of the super-hydrophobic cotton fabric, and long time heat treatment has no influence on the super-hydrophobic effect of the super-hydrophobic cotton fabric.

[0140] Although the application has been disclosed with the preferred embodiments as above, it is not intended to limit the application, and any person skilled in the art can make various modifications and modifications without departing from the spirit and scope of the application, therefore the protection scope of the application should be defined by the claims.

Claims

1. A method for preparing a pH-responsive polymer solution, characterized by, The method comprises the following steps: The bis(3-aminopropyl)-terminated poly(dimethylsiloxane), a diisocyanate compound and a multi-amino compound containing a tertiary amino group are dissolved in an organic solvent to perform pre-polymerization, and then the multi-amino compound containing a tertiary amino group is slowly added to perform addition polymerization to obtain a pH-responsive polymer solution; The multi-amino compound containing a tertiary amino group is one or both of tris(2-aminoethyl)amine and laurylamine dipropylene diamine. The molar ratio of the bis(3-aminopropyl)-terminated poly(dimethylsiloxane), the diisocyanate compound and the multi-amino compound containing a tertiary amino group is 1-4:2-14:2-10.

2. The pH-responsive polymer solution prepared by the method of claim 1.

3. The pH-responsive polymer solution according to claim 2, characterized in that, The mass fraction of the pH-responsive polymer in the pH-responsive polymer solution is 5-25%.

4. A method of preparing a pH-responsive and self-healing superhydrophobic material, characterized in that, The method comprises the following steps: The hydrophobic nanoparticles are added to the pH-responsive polymer solution of claim 2, mixed uniformly to obtain a mixed solution, and then cellulose fiber material is immersed in the mixed solution, taken out, and solidified to obtain a pH-responsive and self-repairing super-hydrophobic material.

5. The method of claim 4, wherein, The hydrophobic nanoparticles are one or more of titanium dioxide, silicon dioxide and carbon black nanoparticles, and the particle size is 1-200 nm.

6. The pH-responsive and self-repairing super-hydrophobic material prepared by the method of claim 4 or 5.

7. The pH-responsive polymer solution of claim 2 or the pH-responsive and self-repairing super-hydrophobic material of claim 6 is applied in the fields of antifouling, self-cleaning, anti-icing, anti-corrosion or water-oil separation.

8. An oil-water separation method characterized by, The pH-responsive and self-repairing super-hydrophobic material of claim 6 is used.

9. A method of improving the pH response, superhydrophobic, self-healing properties of cotton fabric, characterized by, The pH-responsive and self-repairing super-hydrophobic material of claim 6 is used.

10. A method for rapidly realizing the superhydrophobic-hydrophilic-superhydrophobic reversible switching of the surface of cotton fabric, characterized in that, The pH-responsive and self-repairing super-hydrophobic material of claim 6 is used.

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