Preparation method of hydrophobic coating of polysiloxane-polycaprolactone block polymer

Abstract

The invention relates to a preparation method of a hydrophobic coating of a polysiloxane-polycaprolactone block polymer, and relates to the field of polymer material preparation and coating preparation, and the preparation method comprises the following steps: adding ethylene glycol into dimethyl sulfoxide, adding metal sodium, and reacting to obtain an initiator solution; the preparation method comprises the following steps: adding an initiator solution into octamethylcyclotetrasiloxane, reacting, adding water to terminate the reaction, washing, and drying to obtain hydroxyl-terminated ethylene glycol-polydimethylsiloxane; caprolactone and the hydroxyl-terminated ethylene glycol-polydimethylsiloxane are used as raw materials to react under the action of a catalyst and a solvent, and after aftertreatment, a polysiloxane-polycaprolactone block type polymer is obtained; the preparation method comprises the following steps: dissolving a polysiloxane-polycaprolactone block polymer in dichloromethane to obtain a coating solution, coating the surface of a base material with the coating solution, and forming a film through a respiration diagram to obtain the porous hydrophobic coating. The coating has good hydrophobic performance and base material adhesive force, and has good application prospects.

Description

Technical Field

[0001] The present application relates to the field of polymer material preparation and coating preparation, and in particular to a method for preparing a hydrophobic coating of a polysiloxane-polycaprolactone block polymer. Background Art

[0002] Siloxane materials, whose main structure consists of silicon-oxygen bonds and whose silicon atoms can be attached to organic groups on side chains, exhibit strong plasticity and excellent heat and cold resistance, making them widely used in numerous industries. Polycaprolactone, on the other hand, boasts excellent biocompatibility, compatibility with organic polymers, and biodegradability. It can also be used as a cell growth support material, is compatible with many conventional plastics, and is fully degradable in natural environments. Furthermore, polycaprolactone exhibits excellent shape memory and temperature control properties, making it widely used in the production and processing of drug carriers, plasticizers, biodegradable plastics, nanofiber spinning, and shaping materials. These properties have attracted widespread attention from both the industrial and scientific communities. With the continuous advancement of technology, the demand for further optimizing their performance and expanding their application range is growing. For example, in specialized fields with high material performance requirements, such as aerospace and biomedicine, there is a need to develop composite materials with enhanced performance to meet practical application needs. Furthermore, with growing environmental awareness, research on biodegradable, high-performance materials has become a hot topic.

[0003] There are many existing methods for preparing polysiloxane-related composite materials and hydrophobic coatings. For the synthesis of polysiloxane, common methods include different types of ring-opening polymerization reactions, using different initiators to promote the reaction. When preparing hydrophobic coatings, physical coating is used to apply the material with hydrophobic properties directly to the surface of the substrate; chemical grafting is to connect the hydrophobic groups to the substrate material through chemical reactions to achieve a hydrophobic effect; there are also surface modification methods to treat the surface of the material and change its surface properties to obtain hydrophobic properties. These methods have achieved certain results in past practices and have been applied in different application scenarios. However, due to the characteristics and limitations of different methods themselves, they may not be able to fully meet various complex needs in actual applications.

[0004] Existing methods for preparing and applying polysiloxane and polycaprolactone-related materials have certain defects. It is difficult to effectively prepare polysiloxane-polycaprolactone block polymers with a specific structure, and there are difficulties in forming a hydrophobic coating that combines the advantages of both. This limits the further application of polysiloxane in the fields of composite materials and hydrophobicity, so it needs to be improved. Summary of the Invention

[0005] In order to improve the hydrophobic properties of polysiloxane-polycaprolactone block polymers, the present application provides a method for preparing a hydrophobic coating of polysiloxane-polycaprolactone block polymers.

[0006] The present application provides a method for preparing a hydrophobic coating of a polysiloxane-polycaprolactone block polymer using the following technical solution: A method for preparing a hydrophobic coating of a polysiloxane-polycaprolactone block polymer comprises the following steps: S1. Preparation of initiator: adding ethylene glycol to dimethyl sulfoxide and adding metallic sodium, and reacting to obtain an initiator solution; S2. Preparation of hydroxyl-terminated ethylene glycol-polydimethylsiloxane: adding an initiator solution to octamethylcyclotetrasiloxane, reacting, adding water to terminate the reaction, washing, and drying to obtain hydroxyl-terminated ethylene glycol-polydimethylsiloxane; S3. Preparation of polysiloxane-polycaprolactone block polymer: Using caprolactone and the hydroxyl-terminated ethylene glycol-polydimethylsiloxane as raw materials, reacting in the presence of a catalyst and a solvent, and performing post-treatment to obtain a polysiloxane-polycaprolactone block polymer, the structural formula of which is as follows: S4. Preparation of a hydrophobic coating: dissolving a polysiloxane-polycaprolactone block polymer in dichloromethane to obtain a coating liquid, applying the coating liquid to the surface of a substrate, and forming a film through a breathalyzer to obtain a porous hydrophobic coating.

[0007] By synthesizing polysiloxane-polycaprolactone block polymers in steps and preparing a hydrophobic coating, the initiator generated by the reaction of ethylene glycol and metallic sodium is used to activate the polymerization of octamethylcyclotetrasiloxane to form hydroxyl-terminated polydimethylsiloxane, which is then constructed through a catalytic reaction with caprolactone to construct a block structure, so that the chain flexibility of the polysiloxane segment is combined with the low surface energy of polycaprolactone. The polysiloxane segment and the polycaprolactone segment with controllable crystallinity form a composite interface structure through microphase separation, and finally a hydrophobic coating with multi-level pores is formed on the surface of the substrate through breath pattern film formation. This method achieves a synergistic effect of reducing the surface energy of the coating and enhancing the roughness through molecular segment design and porous structure regulation. The prepared hydrophobic coating has excellent hydrophobic properties, substrate adhesion and structural stability, and is suitable for a variety of substrates such as glass, metal, and polymers, and has good application prospects.

[0008] Preferably, in step S1, the molar ratio of ethylene glycol hydroxyl group to metallic sodium is 1:1.

[0009] Preferably, the reaction temperature in step S1 is 25-35° C., and the reaction time is 1-3 h.

[0010] The initiator prepared according to the above conditions can effectively promote the reaction and obtain a hydroxyl-terminated polysiloxane prepolymer with uniform molecular weight distribution, thereby ensuring the interfacial compatibility and microphase separation order of the polysiloxane-polycaprolactone amphiphilic block structure in the hydrophobic coating, and improving the stability and hydrophobic properties of the porous coating.

[0011] Preferably, the molar ratio of the initiator to octamethylcyclotetrasiloxane in step S2 is 1:(1.4-2.2).

[0012] By limiting the feed ratio of initiator to octamethylcyclotetrasiloxane, the degree of polymerization and terminal hydroxyl density of the polysiloxane chain segments are precisely controlled, thereby adjusting the matching of the polysiloxane chain length and the caprolactone block, optimizing the continuity of the hydrophobic siloxane domains and the surface energy gradient distribution during microphase separation, and forming a stable multi-level pore structure and a low-adhesion interface during breath pattern film formation, synergistically improving the superhydrophobic properties of the coating and the adhesion to the substrate, while avoiding the mechanical strength attenuation caused by excessive flexible segments.

[0013] Preferably, the reaction temperature in step S2 is 50-70° C., and the reaction time is 5-7 h.

[0014] The hydroxyl-terminated ethylene glycol-polydimethylsiloxane prepared according to the above conditions has good reaction performance and can effectively improve the hydrophobicity of the coating.

[0015] Preferably, in step S3, the mass ratio of the hydroxyl-terminated ethylene glycol-polydimethylsiloxane to caprolactone is 1:(2-6), the catalyst includes stannous isooctanoate, and the solvent includes cyclohexane.

[0016] By optimizing the mass ratio of caprolactone to hydroxyl-terminated ethylene glycol-polydimethylsiloxane, the low surface energy of the polycaprolactone segment and the flexibility of the polysiloxane segment can be balanced. The efficient catalytic activity of stannous isooctanoate precisely regulates the ring-opening polymerization process, inhibits homopolymerization side reactions, and achieves chemical bonding integrity at the interface of the two blocks. The non-polar solvent environment of cyclohexane promotes uniform dispersion of monomers and orderly assembly of segments, ensuring the kinetic stability of the reaction system. The final block copolymer has both a microphase separation-induced multi-level rough structure and interfacial compatibility, thereby enhancing the synergistic effect of the coating's hydrophobicity and mechanical durability.

[0017] Preferably, the reaction temperature in step S3 is 110-130° C., the reaction time is 22-26 h, and the post-treatment is performed using dichloromethane and petroleum ether.

[0018] According to the above conditions, the polymerization reaction can be carried out efficiently, thereby improving the hydrophobic properties and substrate adhesion of the hydrophobic coating.

[0019] Preferably, in step S4, the substrate is ultrasonically washed and dried for later use; the polysiloxane-polycaprolactone block polymer is dissolved in dichloromethane to obtain a coating liquid with a concentration of 20-30 mg / mL; and the coating liquid is applied to the surface of the substrate in a constant temperature water bath at 25-35°C.

[0020] Ultrasonic cleaning combined with drying treatment effectively removes pollutants from the substrate surface and activates the interface, enhancing the wetting and spreading properties of the coating liquid; the solution system in a specific concentration range balances the solvent volatilization dynamics and the entanglement degree of the polymer chains, ensuring that the template effect of the water vapor condensation droplets in the breathalyzer film formation process is stable and controllable, forming a uniform and interconnected multi-level pore structure; the constant temperature coating conditions suppress the discretization of the pore size distribution caused by the sudden change in the solvent volatilization rate, allowing the low surface energy segments to be directionally enriched at the gas-liquid interface, synergistically improving the superhydrophobic stability of the coating and the interfacial mechanical interlocking strength.

[0021] Preferably, the coating solution in step S4 further includes niobium carbide MXene nanosheets.

[0022] The two-dimensional layered structure of niobium carbide MXene nanosheets is embedded in the polysiloxane-polycaprolactone polymer matrix through interfacial self-assembly, showing good compatibility and forming a micro-nano composite rough surface to reduce the solid-liquid contact area; the interlayer slip effect of MXene nanosheets can enhance the coating's resistance to shear deformation, and after being composited with the polymer to form a homogeneous film, it synergistically achieves a dual breakthrough in superhydrophobic durability and mechanical toughness.

[0023] Preferably, the niobium carbide MXene nanosheets are modified and prepared by the following steps: Niobium carbide MXene nanosheets are added to a dopamine hydrochloride solution and stirred. After washing, the solution is dispersed in a solvent to obtain a niobium carbide MXene nanosheet dispersion. Hexadecyltrimethoxysilane and ethyl orthosilicate are mixed in a solvent, the pH is adjusted to acidic, and the solution is heated and stirred to obtain a composite silica sol. The composite silica sol is added to the niobium carbide MXene nanosheet dispersion, and the solution is heated and stirred to react. After the reaction is completed, the solution is centrifuged, washed, dried, and ground to obtain modified niobium carbide MXene nanosheets.

[0024] Dopamine hydrochloride forms polydopamine, which forms a uniform coating on the MXene surface through π-π conjugation and hydrogen bonding. It not only inhibits the oxidation and stacking of nanosheets, but its abundant phenolic hydroxyl groups also provide active sites for the subsequent anchoring of silica sol. The long-chain hydrophobic groups of hexadecyltrimethoxysilane in the composite silica sol synergistically work with the silicon-oxygen network of ethyl orthosilicate to construct a gradient hydrophobic interface on the MXene surface, forming a three-dimensional coating structure through hydrolysis and condensation, thereby enhancing the chemical bonding between the nanosheets and the polymer matrix. Through the design of the organic-inorganic hybrid interface, MXene can not only exert the micro-nano roughness effect of the two-dimensional sheet structure in the coating, but also improve the dispersion stability through the mechanical interlocking of the silica sol and the adhesion of dopamine hydrochloride, ultimately achieving a double breakthrough in hydrophobic properties and coating durability.

[0025] In summary, this application includes at least one of the following beneficial technical effects: 1. A hydrophobic coating is prepared by synthesizing polysiloxane-polycaprolactone block polymers in steps. The initiator generated by the reaction of ethylene glycol and metallic sodium is used to activate the polymerization of octamethylcyclotetrasiloxane to form hydroxyl-terminated polydimethylsiloxane, which is then catalytically reacted with caprolactone to construct a block structure. The chain flexibility of the polysiloxane segment is combined with the low surface energy of the polycaprolactone. The polysiloxane segment and the polycaprolactone segment with controllable crystallinity form a composite interface structure through microphase separation, and finally a hydrophobic coating with multi-level pores is formed on the surface of the substrate through breath pattern film formation. This method achieves a synergistic effect of reducing the surface energy of the coating and enhancing the roughness through molecular segment design and porous structure regulation. The prepared hydrophobic coating has excellent hydrophobic properties, substrate adhesion and structural stability, and is suitable for a variety of substrates such as glass, metal, and polymers, with good application prospects.

[0026] 2. The two-dimensional layered structure of niobium carbide MXene nanosheets is embedded in the polysiloxane-polycaprolactone polymer matrix through interfacial self-assembly, showing good compatibility and forming a micro-nano composite rough surface to reduce the solid-liquid contact area. The interlayer slip effect of the MXene nanosheets can enhance the coating's resistance to shear deformation. After forming a homogeneous film with the polymer composite, they synergistically achieve a dual breakthrough in superhydrophobic durability and mechanical toughness.

[0027] 3. Dopamine hydrochloride forms a uniform coating on the MXene surface through π-π conjugation and hydrogen bonding, which not only inhibits the oxidation and stacking of nanosheets, but also provides active sites for the subsequent anchoring of silica sol due to its abundant phenolic hydroxyl groups. The long-chain hydrophobic groups of hexadecyltrimethoxysilane in the composite silica sol synergistically interact with the silicon-oxygen network of ethyl orthosilicate to construct a gradient hydrophobic interface on the MXene surface, forming a three-dimensional coating structure through hydrolysis and condensation, thereby enhancing the chemical bonding between the nanosheets and the polymer matrix. Through the design of the organic-inorganic hybrid interface, MXene can not only exert the micro-nano roughness effect of the two-dimensional lamellar structure in the coating, but also improve the dispersion stability through the mechanical interlocking of the silica sol and the adhesion of dopamine hydrochloride, ultimately achieving a double breakthrough in hydrophobicity and coating durability. DETAILED DESCRIPTION

[0028] The present application discloses a method for preparing a hydrophobic coating of a polysiloxane-polycaprolactone block polymer. The raw materials used in the present application can be obtained from commercially available raw materials unless otherwise specified. The present application is further described in detail below in conjunction with the examples: Raw materials description: ethylene glycol (CAS number: 107-21-1), dimethyl sulfoxide (CAS number: 67-68-5), octamethylcyclotetrasiloxane (CAS number: 556-67-2), caprolactone (CAS number: 502-44-3), stannous isooctanoate (CAS number: 301-10-0), cyclohexane (CAS number: 110-82-7), niobium carbide MXene nanosheets (product number 102716) were purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd., dopamine hydrochloride (CAS number: 62-31-7), hexadecyltrimethoxysilane (CAS number: 16415-12-6), and tetraethyl orthosilicate (CAS number: 78-10-4).

[0029] Example 1 S1. Preparation of initiator: In a nitrogen atmosphere, ethylene glycol was added to dimethyl sulfoxide, and metallic sodium was added, with the molar ratio of ethylene glycol hydroxyl group to metallic sodium being 1:1. After reacting at 25°C for 3 hours, an initiator solution with a concentration of 0.3 mol / L was prepared. S2. Preparation of hydroxyl-terminated ethylene glycol-polydimethylsiloxane: The initiator solution was added to octamethylcyclotetrasiloxane, with the molar ratio of initiator to octamethylcyclotetrasiloxane being 1:1.4. The reaction was carried out at 50°C for 7 hours. Deionized water was added to terminate the reaction, and the mixture was washed with anhydrous ethanol until neutral, and then vacuum-dried at 60°C to obtain hydroxyl-terminated ethylene glycol-polydimethylsiloxane. S3. Preparation of polysiloxane-polycaprolactone block polymer: 1 g of caprolactone and 3 g of hydroxyl-terminated ethylene glycol-polydimethylsiloxane were used as raw materials, 0.03 g of stannous isooctanoate was added as a catalyst, 20 mL of cyclohexane was used as a solvent, and the mixture was reacted at 110°C for 26 h under a nitrogen atmosphere. After cooling, dichloromethane and petroleum ether were used for post-treatment. Dichloromethane was added to dissolve the product, and the insoluble stannous isooctanoate catalyst and by-products were removed by vacuum filtration. The filtrate was added dropwise to 5 times the volume of petroleum ether to induce polymer precipitation, and the polymer was washed three times with a mixture of dichloromethane and petroleum ether with a volume ratio of 1:3 and pure petroleum ether, respectively. After vacuum drying at 60°C, a polysiloxane-polycaprolactone block polymer was obtained; S4. Preparation of hydrophobic coating: Place a glass substrate in an ultrasonic bath, wash it three times with anhydrous ethanol and deionized water respectively, and dry it in an oven at 60°C for use; dissolve polysiloxane-polycaprolactone block polymer in dichloromethane, and dissolve it by ultrasonic vibration to obtain a coating liquid with a concentration of 20 mg / mL; apply the coating liquid droplets to the surface of the glass substrate in a constant temperature water tank at 25°C, form a film by breathalyzing, and dry it at 25°C and 80% humidity to obtain a porous hydrophobic coating.

[0030] Example 2 S1. Preparation of initiator: In a nitrogen atmosphere, ethylene glycol was added to dimethyl sulfoxide, and metallic sodium was added, with the molar ratio of ethylene glycol hydroxyl group to metallic sodium being 1:1. After reacting at 35°C for 1 hour, an initiator solution with a concentration of 0.3 mol / L was prepared. S2. Preparation of hydroxyl-terminated ethylene glycol-polydimethylsiloxane: The initiator solution was added to octamethylcyclotetrasiloxane, with the molar ratio of initiator to octamethylcyclotetrasiloxane being 1:1.4. The reaction was carried out at 70°C for 5 hours. Deionized water was added to terminate the reaction, and the mixture was washed with anhydrous ethanol until neutral, and then vacuum-dried at 60°C to obtain hydroxyl-terminated ethylene glycol-polydimethylsiloxane. S3. Preparation of polysiloxane-polycaprolactone block polymer: 1 g of caprolactone and 3 g of hydroxyl-terminated ethylene glycol-polydimethylsiloxane were used as raw materials, 0.03 g of stannous isooctanoate was added as a catalyst, 20 mL of cyclohexane was used as a solvent, and the mixture was reacted at 130°C for 22 h under a nitrogen atmosphere. After cooling, dichloromethane and petroleum ether were used for post-treatment. Dichloromethane was added to dissolve the product, and the insoluble stannous isooctanoate catalyst and by-products were removed by vacuum filtration. The filtrate was added dropwise to 5 times the volume of petroleum ether to induce polymer precipitation, and the polymer was washed three times with a mixture of dichloromethane and petroleum ether in a volume ratio of 1:3 and pure petroleum ether, respectively. After vacuum drying at 60°C, a polysiloxane-polycaprolactone block polymer was obtained; S4. Preparation of hydrophobic coating: Place a glass substrate in an ultrasonic bath, wash it three times with anhydrous ethanol and deionized water respectively, and dry it in an oven at 60°C for use; dissolve the polysiloxane-polycaprolactone block polymer in dichloromethane, and dissolve it by ultrasonic vibration to obtain a coating liquid with a concentration of 20 mg / mL; apply the coating liquid droplets to the surface of the glass substrate in a constant temperature water tank at 35°C, form a film by breathalyzing, and dry it at 25°C and 80% humidity to obtain a porous hydrophobic coating.

[0031] Example 3 S1. Preparation of initiator: In a nitrogen atmosphere, ethylene glycol was added to dimethyl sulfoxide, and metallic sodium was added, with the mass ratio of ethylene glycol hydroxyl group to metallic sodium being 1:1. After reacting at 30°C for 2 hours, an initiator solution with a concentration of 0.3 mol / L was prepared. S2. Preparation of hydroxyl-terminated ethylene glycol-polydimethylsiloxane: The initiator solution was added to octamethylcyclotetrasiloxane, with the molar ratio of initiator to octamethylcyclotetrasiloxane being 1:1.4. The reaction was carried out at 60°C for 6 hours. Deionized water was added to terminate the reaction, and the mixture was washed with anhydrous ethanol until neutral, and then vacuum-dried at 60°C to obtain hydroxyl-terminated ethylene glycol-polydimethylsiloxane. S3. Preparation of polysiloxane-polycaprolactone block polymer: 1 g of caprolactone and 3 g of hydroxyl-terminated ethylene glycol-polydimethylsiloxane were used as raw materials, 0.03 g of stannous isooctanoate was added as a catalyst, 20 mL of cyclohexane was used as a solvent, and the mixture was reacted at 120°C for 24 h under a nitrogen atmosphere. After cooling, dichloromethane and petroleum ether were used for post-treatment. Dichloromethane was added to dissolve the product, and the insoluble stannous isooctanoate catalyst and by-products were removed by vacuum filtration. The filtrate was added dropwise to 5 times the volume of petroleum ether to induce polymer precipitation, and the polymer was washed three times with a mixture of dichloromethane and petroleum ether with a volume ratio of 1:3 and pure petroleum ether, respectively. After vacuum drying at 60°C, a polysiloxane-polycaprolactone block polymer was obtained; S4. Preparation of hydrophobic coating: Place a glass substrate in an ultrasonic bath, wash it three times with anhydrous ethanol and deionized water respectively, and dry it in an oven at 60°C for later use; dissolve the polysiloxane-polycaprolactone block polymer in dichloromethane, and dissolve it by ultrasonic vibration to obtain a coating liquid with a concentration of 20 mg / mL; apply the coating liquid droplets to the surface of the glass substrate in a constant temperature water tank at 30°C, form a film by breathalyzing, and dry it at 25°C and 80% humidity to obtain a porous hydrophobic coating.

[0032] Example 4 is based on Example 3. The only difference between Example 4 and Example 3 is that the molar ratio of the initiator to octamethylcyclotetrasiloxane in Example 4 is 1:2.2.

[0033] Example 5 Example 5 is based on Example 3. The only difference between Example 5 and Example 3 is that in Example 5, the mass ratio of hydroxyl-terminated ethylene glycol-polydimethylsiloxane to caprolactone is 1:2.

[0034] Example 6 Example 6 is based on Example 3. The only difference between Example 6 and Example 3 is that in Example 6, the molar ratio of the initiator to octamethylcyclotetrasiloxane is 1:2.2, and the mass ratio of caprolactone to hydroxyl-terminated ethylene glycol-polydimethylsiloxane in step (3) is 1:2.

[0035] Example 7 Example 7 is based on Example 3. The only difference between Example 7 and Example 3 is that in Example 7, the mass ratio of hydroxyl-terminated ethylene glycol-polydimethylsiloxane to caprolactone is 1:6.

[0036] Example 8 Example 8 is based on Example 3. The only difference between Example 8 and Example 3 is that in Example 8, the molar ratio of the initiator to octamethylcyclotetrasiloxane is 1:2.2, and the mass ratio of caprolactone to hydroxyl-terminated ethylene glycol-polydimethylsiloxane in step (3) is 1:6.

[0037] The water contact angle test was performed on the molar ratios of different initiators and octamethylcyclotetrasiloxane (D4) prepared in Examples 3-8, the mass ratios of different caprolactone and hydroxyl-terminated ethylene glycol-polydimethylsiloxane (EG-PDMS-PCL), and the hydrophobic coatings of different concentrations. The test results are shown in Table 1: When the molar ratio of initiator to octamethylcyclotetrasiloxane is 1:2.2, the mass ratio of caprolactone to hydroxyl-terminated ethylene glycol-polydimethylsiloxane is 1:6, and the concentration of the hydrophobic coating is 20 mg / mL, the water contact angle of the coating surface reaches 139°; when the molar ratio of initiator to octamethylcyclotetrasiloxane is fixed, the contact angle of the prepared porous hydrophobic coating gradually increases with the increase of caprolactone; in the process of gradually increasing the ratio of initiator to octamethylcyclotetrasiloxane, the maximum hydrophobic angle of the hydrophobic surface coating also increases, mainly because as the content of octamethylcyclotetrasiloxane in the initiator increases, the proportion of hydroxyl groups in it decreases, so the water contact angle of the hydrophobic surface increases, but the increase in the maximum contact angle is small. Therefore, the optimal ratio is that the molar ratio of initiator to octamethylcyclotetrasiloxane is 1:2.2, the mass ratio of hydroxyl-terminated ethylene glycol-polydimethylsiloxane to caprolactone is 1:6, and when the concentration of the hydrophobic coating is 20 mg / mL, the hydrophobicity of the coating surface is optimal.

[0038] Example 9 Example 9 is based on Example 8. The only difference between Example 9 and Example 8 is that the coating liquid in step S4 of Example 9 further includes niobium carbide MXene nanosheets.

[0039] S4. Preparation of a hydrophobic coating: Place a glass substrate in an ultrasonic bath, wash it three times with anhydrous ethanol and deionized water, respectively, and dry it in an oven at 60°C for later use; mix polysiloxane-polycaprolactone block polymer and niobium carbide MXene nanosheets in dichloromethane, and after ultrasonic vibration, obtain a coating solution with a polymer concentration of 20 mg / mL and a niobium carbide MXene nanosheet concentration of 0.4 mg / mL; apply the coating droplets to the surface of the glass substrate in a constant temperature water tank at 30°C, form a film by breathalyzing, and dry it at 25°C and 80% humidity to obtain a porous hydrophobic coating.

[0040] Example 10 Example 10 is based on Example 9. The only difference between Example 10 and Example 9 is that the niobium carbide MXene nanosheets in Example 10 are modified and prepared by the following steps: Niobium carbide MXene nanosheets were added to a 1% dopamine hydrochloride aqueous solution with a solid-liquid ratio of 1:20, and the pH was adjusted to 8.5 using 30% ammonia water. The mixture was stirred at 200 rpm at 30°C for 12 hours, washed with anhydrous ethanol until neutral, and ultrasonically dispersed in anhydrous ethanol to obtain a niobium carbide MXene nanosheet dispersion. Hexadecyltrimethoxysilane and ethyl orthosilicate were dissolved in ethanol at a mass ratio of 1:3, and a 0.1 mol / L hydrochloric acid aqueous solution was added to adjust the pH to 4.5. The mixture was stirred at 200 rpm at 40°C for 6 hours to obtain a composite silica sol. The composite silica sol was added to the activated niobium carbide MXene nanosheet dispersion, and the mixture was stirred at 200 rpm at 60°C for 12 hours. After the reaction, the mixture was centrifugally washed with deionized water and anhydrous ethanol, dried in a vacuum at 60°C, and ground to obtain modified niobium carbide MXene nanosheets.

[0041] Performance testing The water contact angle of the hydrophobic coating of the sample was tested, and the test results are recorded in Table 1 Table 1 Test results of water contact angle of hydrophobic coating As can be seen from Table 1, the water contact angle of Example 8 is 139°, which shows that the polysiloxane-polycaprolactone block polymer prepared in the present application has good hydrophobic properties.

[0042] As can be seen from Table 1, the only difference between Examples 8 and 9 and Example 3 is that in Example 8, niobium carbide MXene nanosheets are added to the coating liquid, and the hydrophobicity is improved through the synergistic effect of the filler and the polymer; in Example 9, the niobium carbide MXene nanosheets are further modified, and the performance is further improved.

[0043] This specific embodiment is merely an explanation of the present application and does not limit the present application. Based on the above description, relevant personnel can make various changes and modifications without departing from the technical scope of the present application. The technical scope of the present application is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A method for preparing a hydrophobic coating of a polysiloxane-polycaprolactone block polymer, characterized in that: The following steps are involved: S1. Preparation of initiator: adding ethylene glycol to dimethyl sulfoxide and adding metallic sodium, and reacting to obtain an initiator solution; S2. Preparation of hydroxyl-terminated ethylene glycol-polydimethylsiloxane: adding an initiator solution to octamethylcyclotetrasiloxane, reacting, adding water to terminate the reaction, washing, and drying to obtain hydroxyl-terminated ethylene glycol-polydimethylsiloxane; S3. Preparation of polysiloxane-polycaprolactone block polymer: Using caprolactone and the hydroxyl-terminated ethylene glycol-polydimethylsiloxane as raw materials, reacting in the presence of a catalyst and a solvent, and performing post-treatment to obtain a polysiloxane-polycaprolactone block polymer, the structural formula of which is as follows: S4. Preparation of a hydrophobic coating: dissolving a polysiloxane-polycaprolactone block polymer in dichloromethane to obtain a coating liquid, applying the coating liquid to the surface of a substrate, and forming a film through a breathalyzer to obtain a porous hydrophobic coating.

2. The method for preparing a hydrophobic coating of a polysiloxane-polycaprolactone block polymer according to claim 1, wherein: In step S1, the molar ratio of ethylene glycol hydroxyl group to metallic sodium is 1:

1.

3. The method for preparing a hydrophobic coating of a polysiloxane-polycaprolactone block polymer according to claim 2, wherein: In step S1, the reaction temperature is 25-35° C., and the reaction time is 1-3 h.

4. The method for preparing a hydrophobic coating of a polysiloxane-polycaprolactone block polymer according to claim 1, wherein: The molar ratio of the initiator to octamethylcyclotetrasiloxane in step S2 is 1:(1.4-2.2).

5. The method for preparing a hydrophobic coating of a polysiloxane-polycaprolactone block polymer according to claim 4, wherein: In step S2, the reaction temperature is 50-70° C., and the reaction time is 5-7 h.

6. The method for preparing a hydrophobic coating of a polysiloxane-polycaprolactone block polymer according to claim 1, wherein: In step S3, the mass ratio of the hydroxyl-terminated ethylene glycol-polydimethylsiloxane to caprolactone is 1:(2-6), the catalyst includes stannous isooctanoate, and the solvent includes cyclohexane.

7. The method for preparing a hydrophobic coating of a polysiloxane-polycaprolactone block polymer according to claim 6, characterized in that: In step S3, the reaction temperature is 110-130° C., the reaction time is 22-26 h, and the post-treatment is performed using dichloromethane and petroleum ether.

8. The method for preparing a hydrophobic coating of a polysiloxane-polycaprolactone block polymer according to claim 1, characterized in that: In step S4, the substrate is ultrasonically washed and dried for later use; the polysiloxane-polycaprolactone block polymer is dissolved in dichloromethane to obtain a coating liquid with a concentration of 20-30 mg / mL; and the coating liquid is applied to the surface of the substrate in a constant temperature water bath at 25-35°C.

9. The method for preparing a hydrophobic coating of a polysiloxane-polycaprolactone block polymer according to claim 8, characterized in that: The coating solution in step S4 also includes niobium carbide MXene nanosheets.

10. The method for preparing a hydrophobic coating of a polysiloxane-polycaprolactone block polymer according to claim 9, characterized in that: The niobium carbide MXene nanosheets are modified and prepared by the following steps: Niobium carbide MXene nanosheets are added to a dopamine hydrochloride solution and stirred. After washing, the solution is dispersed in a solvent to obtain a niobium carbide MXene nanosheet dispersion. Hexadecyltrimethoxysilane and ethyl orthosilicate are mixed in a solvent, the pH is adjusted to acidic, and the solution is heated and stirred to obtain a composite silica sol. The composite silica sol is added to the niobium carbide MXene nanosheet dispersion, and the solution is heated and stirred to react. After the reaction is completed, the solution is centrifuged, washed, dried, and ground to obtain modified niobium carbide MXene nanosheets.

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