Raspberry-shaped super-hydrophobic composite microsphere as well as preparation method and application thereof

Abstract

The invention discloses raspberry-shaped super-hydrophobic composite microspheres as well as a preparation method and application thereof. The raspberry-shaped super-hydrophobic composite microsphere comprises a core microsphere and nano-particles, the nano-particles are attached to the surface of the core microsphere through covalent bonds generated by a thiol-ene click chemical reaction, and a raspberry-shaped heterostructure is constructed; wherein the surface of at least one of the core microspheres and the nanoparticles is modified with C1-C18 alkyl and / or phenyl. According to the raspberry-shaped super-hydrophobic composite microspheres, the surfaces of chemical components are modified with alkyl and / or phenyl, and intrinsic hydrophobicity is provided; on the microstructure, the lotus leaf surface is simulated, and micron-nanometer combined multistage roughness is constructed; meanwhile, a C-S covalent bond formed based on a thiol-ene click reaction enables the composite microsphere to have relatively high strength and performance stability at the same time. The super-hydrophobic coating prepared by matching the raspberry-shaped super-hydrophobic composite microspheres with a binder is stable in structure and high in wear resistance and weather resistance.

Description

Technical Field

[0001] This invention relates to the field of polymer functional materials technology, and in particular to a raspberry-like superhydrophobic composite microsphere, its preparation method, and its application. Background Technology

[0002] The physical phenomenon of a droplet forming a contact angle greater than 150° and a roll-off angle less than 10° on a solid surface is called superhydrophobicity. This phenomenon is widely found in nature, such as on lotus leaves, water strider legs, and butterfly wings. Superhydrophobic properties have wide applications in self-cleaning, corrosion prevention, anti-icing, and pipeline transportation. The realization of superhydrophobic properties mainly benefits from the construction of micron- and nanon-level hierarchical structures and the modification with low surface area materials.

[0003] Raspberry-like composite particles are assembled from two or more micron- and nano-sized particles of different sizes, integrating multiple unique properties. Their properties can be altered by controlling the type and size of the particles, achieving regulation in magnetic, optical, mechanical, thermodynamic, and catalytic properties. Furthermore, the unique micro- and nano-multi-roughness structures constructed from raspberry-like composite particles can meet the surface roughness requirements of superhydrophobicity, and after modification with low-surface-weight materials, they hold promise for forming superhydrophobic surfaces. Existing techniques synthesize raspberry-like microspheres with polymethyl methacrylate (PMMA) as the core and silica as the shell using the sol-gel method, and then prepare superhydrophobic coatings from these microspheres. While this method constructs raspberry-like microspheres, the PMMA microspheres and SiO2 microspheres are only physically adsorbed, resulting in significant structural stability issues. Existing techniques also utilize the condensation of hydroxyl groups to form tertiary raspberry-like particles by copolymerizing SiO2 particles with P(St-co-KH570) microspheres. Although this method combines microspheres of different sizes through chemical bonds, it still requires complex hydrophobic modifiers for hydrophobic modification. The surface of the hydrophobic modified layer is easily damaged, and once damaged, the hydrophobic effect is completely lost.

[0004] Therefore, there is an urgent need to prepare a raspberry-like composite microsphere with strong bonding between microspheres of different sizes and self-hydrophobic structure, which can provide a possibility for the realization of superhydrophobic coatings. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a raspberry-shaped superhydrophobic composite microsphere, its preparation method and application, to solve the technical problems in the prior art where microspheres of different sizes are combined only by physical adsorption, resulting in poor structural stability, and the lack of self-hydrophobic properties of the raspberry-shaped composite microsphere, leading to complete failure of the hydrophobic effect after the surface of the hydrophobic modification layer is damaged.

[0006] In a first aspect, the present invention provides a raspberry-like superhydrophobic composite microsphere, comprising: a core microsphere and nanoparticles, wherein the nanoparticles are attached to the surface of the core microsphere by covalent bonds generated by a thiol-alkene click chemistry reaction, thereby constructing a raspberry-like heterostructure; wherein the surface of the core microsphere is modified with thiol functional groups and / or alkenyl functional groups, and the surface of the nanoparticles is correspondingly modified with alkenyl functional groups and / or thiol functional groups, and at least one of the core microspheres and nanoparticles is modified with C1-C2. 18 Alkyl and / or phenyl.

[0007] Secondly, the present invention provides a method for preparing raspberry-shaped superhydrophobic composite microspheres, comprising the following steps: Provide core microspheres and nanoparticles; Nanoparticles are attached to the surface of the core microspheres through covalent bonds generated by the thiol-ene click chemical reaction, constructing a raspberry-like heterostructure and obtaining raspberry-like superhydrophobic composite microspheres.

[0008] Thirdly, the present invention provides an application of raspberry-shaped superhydrophobic composite microspheres, which are used to prepare superhydrophobic coatings.

[0009] Compared with the prior art, the beneficial effects of the present invention include: The raspberry-like superhydrophobic composite microspheres of this invention, in terms of chemical composition, have surface modifications with alkyl and / or phenyl groups to provide intrinsic hydrophobicity; in terms of microstructure, they mimic the surface of a lotus leaf, constructing a multi-level roughness combining micron and nanometer dimensions; simultaneously, CS covalent bonds formed based on the mercapto-ene click reaction endow the composite microspheres with both high strength and performance stability. The superhydrophobic coating made using the above-mentioned raspberry-like superhydrophobic composite microspheres in conjunction with a binder exhibits stable structure and high wear resistance and weather resistance. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the synthesis reaction mechanism of the raspberry-like superhydrophobic composite microspheres prepared in Example 1 of this invention; Figure 2 This is a microscopic morphology diagram of the raspberry-shaped superhydrophobic composite microspheres prepared in Example 1 of the present invention; Figure 3 This is a diagram illustrating the superhydrophobic effect of the superhydrophobic coating on the surface of the cement board on water droplets in Embodiment 1 of the present invention. Figure 4 This is a test diagram of the wetting performance of the superhydrophobic coating prepared in Example 1 of the present invention; Figure 5 This is a diagram illustrating the superhydrophobic effect of the superhydrophobic coating on the filter paper surface on water droplets in Embodiment 2 of the present invention. Figure 6 This is a diagram illustrating the superhydrophobic effect of the superhydrophobic coating on the copper plate surface on water droplets in Embodiment 3 of the present invention. Figure 7 This is a diagram illustrating the superhydrophobic effect of the superhydrophobic coating on the surface of the wood board in Embodiment 4 of the present invention on water droplets. Figure 8 This is a microscopic morphology diagram of the composite microspheres prepared in Comparative Example 1 of the present invention. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0012] In a first aspect, the present invention provides a raspberry-like superhydrophobic composite microsphere, comprising: a core microsphere and nanoparticles, wherein the nanoparticles are attached to the surface of the core microsphere by covalent bonds generated by a thiol-alkene click chemistry reaction, thereby constructing a raspberry-like heterostructure; wherein the surface of the core microsphere is modified with thiol functional groups and / or alkenyl functional groups, and the surface of the nanoparticles is correspondingly modified with alkenyl functional groups and / or thiol functional groups, and at least one of the core microspheres and nanoparticles is modified with C1-C2. 18 Alkyl and / or phenyl.

[0013] The raspberry-like superhydrophobic composite microspheres of the present invention have the following chemical composition: the surface is modified with alkyl and / or phenyl groups to provide intrinsic hydrophobicity; the microstructure mimics the surface of a lotus leaf to construct a multi-level roughness combining micron and nanometer dimensions; at the same time, the CS covalent bonds formed based on the mercapto-ene click reaction enable the composite microspheres to have both high strength and performance stability.

[0014] In this embodiment, the core microsphere is a mercapto-conjugated polysilsesquioxane microsphere (SH-POSS), and some or all of the remaining functional groups on its framework silicon atoms are independently bounded by C1-C2. 18 Alkyl or phenyl groups are optionally substituted, and the nanoparticles are vinyl-conjugated polysilsesquioxane nanoparticles (Vinyl-POSS), wherein some or all of the remaining functional groups on the backbone silicon atoms are independently C1-C2. 18 Alkyl or phenyl groups may be optionally substituted. During the experiment, the inventors discovered that attaching mercapto-containing conjugated polysilsesquioxane as the core microsphere and vinyl-containing conjugated polysilsesquioxane as nanoparticles to the surface of the core microsphere is beneficial for further improving the hydrophobic properties of the raspberry-like superhydrophobic composite microspheres.

[0015] In this embodiment, the core microspheres are synthesized by catalytic hydrolysis and co-condensation polymerization of mercaptosilicone monomers and a first low surface energy silicon monomer.

[0016] Preferably, the mercaptosilicone monomer comprises C1-C 18 Mercaptoalkyltrialkoxysilanes, including but not limited to C1-C 18mercaptoalkyltrimethoxysilane, C1-C 18 Mercaptoalkyltriethoxysilanes, etc., and further including but not limited to γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, C 10 -C 18 Long-chain mercaptoalkyltrimethoxysilane, C 10 -C 18 One or more of the long-chain mercaptoalkyltriethoxysilanes.

[0017] Preferably, the first low surface energy silicon monomer comprises C1-C 18 Trialkoxysilanes optionally substituted with alkyl or phenyl groups, including but not limited to C1-C4 alkyl- or C2 ... 18 Alkyltrimethoxysilane, C1-C 18 Alkyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, etc., further including but not limited to one or more of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, octadecyltrimethoxysilane, and octadecyltriethoxysilane.

[0018] Preferably, the mass ratio of mercaptosilicone monomer to the first low surface energy silicon monomer is 1:(3-13). The mercapto-containing conjugated polysilsesquioxane microspheres, as the core microspheres, need to provide sufficient covalent bond sites. If the proportion of mercaptosilicone monomer is too low, it will result in fewer bond sites, weak bonding, and reduced coating wear resistance. If the proportion of the first low surface energy silicon monomer is too low, although it serves as the internal core microsphere and has fewer direct contact points with the droplets, it will still have a certain adverse effect on hydrophobicity.

[0019] Preferably, the preparation process of the core microspheres includes: mixing mercaptosilicone monomer, a first low surface energy silicon monomer and a first water evenly, so that the organosilicon monomer is dispersed in the reaction system in the form of oil droplets, then adding a first ammonia water, and after a first reaction, obtaining mercapto-containing conjugated polysilsesquioxane microspheres.

[0020] More preferably, the mass fraction of the first ammonia solution is 20%-30%.

[0021] More preferably, the mass ratio of the first water to the mercaptosilicon monomer + the first low surface energy silicon monomer and the first ammonia is 100:(15-25):(0.05-0.2), specifically 100:20:(0.05-0.2).

[0022] More preferably, the mercaptosilicon monomer, the first low surface energy silicon monomer, and the first water are mixed evenly by stirring.

[0023] The stirring temperature is room temperature, the stirring time is 10-20 min, and the stirring speed is 100-300 r / min.

[0024] More preferably, the temperature of the first reaction is 20-40°C, and the time of the first reaction is 2-4 hours.

[0025] More preferably, the first reaction is carried out under stirring conditions at a stirring rate of 100-300 r / min.

[0026] More preferably, after the first reaction is completed, the process further includes: solid-liquid separation, washing and drying to obtain mercapto-conjugated polysilsesquioxane microspheres.

[0027] Vacuum drying is used, with a drying temperature of 40-80℃ and a drying time of 8-24 hours.

[0028] In this embodiment, the nanoparticles are synthesized by catalytic hydrolysis and co-condensation polymerization of vinyl silicon monomer and a second low surface energy silicon monomer under emulsifier conditions.

[0029] Preferably, the vinylsilicon monomer includes a trialkoxysilane with an ethylene end group, including but not limited to trimethoxysilane with an ethylene end group, triethoxysilane with an ethylene end group, etc., and further including but not limited to one or more of vinyltrimethoxysilane and vinyltriethoxysilane.

[0030] Preferably, the second low surface energy silicon monomer comprises C1-C 18 Trialkoxysilanes optionally substituted with alkyl or phenyl groups, including but not limited to C1-C4 alkyl- or C2 ... 18 Alkyltrimethoxysilane, C1-C 18 Alkyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, etc., further including but not limited to one or more of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, octadecyltrimethoxysilane, and octadecyltriethoxysilane.

[0031] Preferably, the mass ratio of vinyl silicon monomer to the second low surface energy silicon monomer is 1:(3-6). Vinyl conjugated polysilsesquioxane nanoparticles, as the outermost layer of the raspberry-like composite microspheres, directly contact the droplet. Although vinyl has a lower specific surface energy, it still lags behind alkyl and phenyl monomers. If the proportion of the second low surface energy silicon monomer is too low, the surface energy of the composite microspheres will be too high, resulting in decreased hydrophobicity. If the proportion of vinyl silicon monomer is too low, there will be fewer covalent bond points, leading to weak microsphere bonding and reduced wear resistance and weather resistance.

[0032] Preferably, the emulsifier is one or more of sodium dodecylbenzenesulfonate, fatty alcohol polyoxyethylene ether, Triton X-100, and Tween 80.

[0033] Preferably, the preparation process of nanoparticles includes: mixing a second water, an emulsifier, and a second ammonia water evenly, then adding a vinyl silicon monomer and a second low surface energy silicon monomer, and after a second reaction, obtaining a vinyl-containing conjugated polysilsesquioxane emulsion.

[0034] More preferably, the mass fraction of the second ammonia solution is 20%-30%.

[0035] More preferably, the mass ratio of the second water, the emulsifier, and the second ammonia is 100:(0.1-0.5):(0.05-0.2).

[0036] More preferably, the second water, emulsifier, and second ammonia are mixed evenly by stirring.

[0037] The stirring temperature was room temperature, the stirring time was 0.5-1h, and the stirring rate was 100-300 r / min.

[0038] More preferably, the mass ratio of vinyl silicon monomer + second low surface energy silicon monomer to second water is (15-25):100, specifically (19-20):100.

[0039] More preferably, the temperature of the second reaction is 20-40°C, and the time of the second reaction is 8-12 hours.

[0040] More preferably, the second reaction is carried out under stirring conditions at a stirring rate of 100-300 r / min.

[0041] Preferably, the mass ratio of the vinyl-containing conjugated polysilsesquioxane emulsion to the mercapto-containing conjugated polysilsesquioxane microspheres is 100:(10-40), more preferably 100:(15-35). If the proportion of mercapto-containing conjugated polysilsesquioxane microspheres is too high, the small-sized vinyl particles will not be able to cover the surface of the microspheres, and a dense raspberry structure cannot be formed, affecting the roughness. If the proportion of mercapto-containing conjugated polysilsesquioxane microspheres is too low, the vinyl-containing conjugated polysilsesquioxane nanoparticles will have nowhere to be grafted, and it will only be a mixture of micro and nanoparticles, which will also affect the roughness.

[0042] In this embodiment, the particle size ratio of the core microspheres to the nanoparticles is 1:(0.06-0.4).

[0043] In this embodiment, the core microspheres have a particle size of 2-5 μm, and the nanoparticles have a particle size of 300-800 nm.

[0044] Secondly, the present invention provides a method for preparing raspberry-shaped superhydrophobic composite microspheres, comprising the following steps: S1 provides core microspheres and nanoparticles; S2. Nanoparticles attach to the surface of the core microsphere through covalent bonds generated by the thiol-ene click chemical reaction, constructing a raspberry-like heterostructure and obtaining a raspberry-like superhydrophobic composite microsphere.

[0045] In this embodiment, step S2 includes: mixing vinyl-containing conjugated polysilsesquioxane emulsion, mercapto-containing conjugated polysilsesquioxane microspheres and photoinitiator evenly, and then performing a mercapto-ene click reaction to obtain raspberry-like superhydrophobic composite microspheres.

[0046] Preferably, the photoinitiator is one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin dimethyl ether, and 2,2-dimethoxy-2-phenylacetophenone.

[0047] Preferably, the mass ratio of mercapto-conjugated polysilsesquioxane microspheres to photoinitiator is 100:(1-10).

[0048] Preferably, the emulsion containing vinyl conjugated polysilsesquioxane, the microspheres containing mercapto conjugated polysilsesquioxane, and the photoinitiator are mixed evenly by stirring.

[0049] The stirring temperature is room temperature, the stirring time is 10-20 min, and the stirring speed is 100-300 r / min.

[0050] In this embodiment, the temperature of the thiol-ene click chemical reaction is 50-70°C, and the time of the thiol-ene click chemical reaction is 10-30 min.

[0051] In this embodiment, the mercapto-ene click chemistry reaction is carried out under ultraviolet light.

[0052] Preferably, the wavelength of the ultraviolet light is 300-400nm, and more preferably 365nm.

[0053] Preferably, after the thiol-ene click reaction is completed, the process further includes: solid-liquid separation, washing, and drying to obtain raspberry-like superhydrophobic composite microspheres.

[0054] Vacuum drying is used, with a drying temperature of 40-80℃ and a drying time of 8-24 hours.

[0055] Thirdly, the present invention provides an application of raspberry-shaped superhydrophobic composite microspheres, which are used to prepare superhydrophobic coatings.

[0056] This invention does not limit the method of applying the raspberry-shaped superhydrophobic composite microspheres to prepare superhydrophobic coatings; those skilled in the art can choose according to the actual situation. For example, the raspberry-shaped superhydrophobic composite microspheres can be directly dispersed in a dispersion solvent, then coated onto the substrate surface and dried to form a superhydrophobic coating; alternatively, the raspberry-shaped superhydrophobic composite microspheres and a binder can be dispersed in a dispersion solvent, then coated onto the substrate surface and fully cured to form a superhydrophobic coating; furthermore, the raspberry-shaped superhydrophobic composite microspheres can be dispersed in a dispersion solvent, then coated onto the substrate surface that has been pre-coated with a binder and semi-cured, and fully cured to form a superhydrophobic coating. This invention preferably uses the third method, as the superhydrophobic coating prepared with the binder exhibits good wear resistance and weather resistance, retaining its superhydrophobic properties even after wear resistance testing and six months of outdoor placement.

[0057] This invention does not limit the types of substrates, binders, and dispersion solvents, and those skilled in the art can select them according to actual conditions. For example, substrates include cement, filter paper, copper plates, wood boards, etc.; binders include single-component acrylic resins, single-component epoxy resins, polyvinyl acetate, single-component polyurethanes, etc.; and since different binders correspond to different curing temperatures and durations, this invention does not limit the specific semi-curing and curing conditions, and those skilled in the art can also select them according to actual conditions. Semi-curing refers to the adhesive layer having adhesiveness, capable of adhering to and embedding the composite microspheres, and forming a permanent bond with the composite microspheres during the subsequent complete curing process; complete curing refers to the adhesive layer no longer having adhesiveness and the curing reaction essentially terminating.

[0058] The present invention does not limit the coating method, and those skilled in the art can choose according to the actual situation, such as spin coating, dip coating, spray coating, etc.

[0059] Preferably, the dispersion solvent includes one or more of ethanol, acetone, n-hexane, toluene, xylene, ethyl acetate, carbon tetrachloride, and methyl acetate.

[0060] Preferably, the mass ratio of raspberry-shaped superhydrophobic composite microspheres to the dispersing solvent is (2-8):100.

[0061] Example 1 (1) Mix 8g of γ-mercaptopropyltrimethoxysilane, 32g of methyltrimethoxysilane and 200g of deionized water, and then stir at room temperature for 15min at a rate of 200 r / min; then add 0.2g of 25wt% ammonia water, react at 30℃ for 3h and then stop stirring. After filtration, washing and vacuum drying at 60℃ for 12h, mercapto-conjugated polysilsesquioxane microspheres are obtained.

[0062] (2) Mix 100g of deionized water, 0.5g of sodium dodecylbenzenesulfonate and 0.1g of ammonia with a concentration of 25wt% and stir at room temperature for 0.5h; control the system temperature at 30℃, then add 4g of vinyltrimethoxysilane and 15g of methyltrimethoxysilane, keep warm for 10h to obtain a vinyl conjugated polysilsesquioxane emulsion.

[0063] (3) Add 30g of mercapto-containing conjugated polysilsesquioxane microspheres and 2g of benzoin dimethyl ether photoinitiator to all the vinyl-containing conjugated polysilsesquioxane emulsions prepared in step (2). Stir mechanically at room temperature for 20min to disperse them evenly. Then place them under a UV lamp with a wavelength of 365nm at 60℃ for 15min to complete the mercapto-ene click reaction. Finally, centrifuge, wash, and vacuum dry at 60℃ for 12h to obtain raspberry-like superhydrophobic composite microspheres.

[0064] (4) Add 10g of raspberry-shaped superhydrophobic composite microspheres to 200g of ethanol to obtain a dispersion. Apply a single-component polyurethane adhesive (Quzhou Dongkai Adhesive Co., Ltd., P-599 type) to the cleaned and dried cement board surface for semi-curing (30℃, 2h). Then spray the raspberry-shaped superhydrophobic composite microsphere dispersion onto the cement board surface and dry it at 60℃ for 6h to fully cure it and obtain a superhydrophobic coating.

[0065] Example 2 (1) Mix 6g of γ-mercaptopropyltriethoxysilane, 34g of phenyltrimethoxysilane and 200g of deionized water, and then stir at room temperature for 20min at a rate of 100 r / min; then add 0.3g of 25wt% ammonia water, react at 40℃ for 2h and then stop stirring. After filtration, washing and vacuum drying at 60℃ for 12h, mercapto-conjugated polysilsesquioxane microspheres are obtained.

[0066] (2) Mix 100g of deionized water, 0.3g of fatty alcohol polyoxyethylene ether and 0.1g of 25wt% ammonia water and stir at room temperature for 1h; control the system temperature at 30℃, then add 3g of vinyltriethoxysilane and 17g of methyltrimethoxysilane, keep warm for 12h to obtain a vinyl conjugated polysilsesquioxane emulsion.

[0067] (3) Add 25g of mercapto-containing conjugated polysilsesquioxane microspheres and 1g of 2-hydroxy-2-methyl-1-phenyl-1-propanone photoinitiator to all the vinyl-containing conjugated polysilsesquioxane emulsions prepared in step (2) in sequence. Stir mechanically at room temperature for 15min to disperse it evenly. Then place it under a UV lamp with a wavelength of 365nm at 70℃ for 15min to complete the mercapto-ene click reaction. Finally, centrifuge, wash and vacuum dry at 80℃ for 8h to obtain raspberry-like superhydrophobic composite microspheres.

[0068] (4) Add 13g of raspberry-shaped superhydrophobic composite microspheres to 200g of ethanol to obtain a dispersion. Coat the filter paper surface with polyvinyl acetate adhesive (Guangzhou Yijiang Chemical Co., Ltd., Type A) for semi-curing (25℃, 1h). Then spray the raspberry-shaped superhydrophobic composite microsphere dispersion onto the filter paper surface and dry at 80℃ for 6h to fully cure, thus obtaining a superhydrophobic coating.

[0069] Example 3 (1) Mix 3g of γ-mercaptopropyltriethoxysilane, 37g of octyltrimethoxysilane and 200g of deionized water, and then stir at room temperature for 10min at a rate of 300 r / min; then add 0.4g of 25wt% ammonia water, react at 20℃ for 4h and then stop stirring. After filtration, washing and vacuum drying at 40℃ for 24h, mercapto-conjugated polysilsesquioxane microspheres are obtained.

[0070] (2) Mix 100g of deionized water, 0.1g of Tween 80 and 0.2g of 25wt% ammonia water and stir at room temperature for 1h; control the system temperature at 40℃, then add 4g of vinyltriethoxysilane and 15g of phenyltriethoxysilane, keep the reaction at the temperature for 8h, and obtain a vinyl conjugated polysilsesquioxane emulsion.

[0071] (3) Add 35g of mercapto-containing conjugated polysilsesquioxane microspheres and 1g of 2,2-dimethoxy-2-phenylacetophenone photoinitiator to all the vinyl-containing conjugated polysilsesquioxane emulsions prepared in step (2) in sequence. Stir mechanically at room temperature for 15min to disperse it evenly. Then place it under a UV lamp with a wavelength of 365nm at 70℃ for 25min to complete the mercapto-ene click reaction. Finally, centrifuge, wash and vacuum dry at 40℃ for 24h to obtain raspberry-like superhydrophobic composite microspheres.

[0072] (4) Add 8g of raspberry-shaped superhydrophobic composite microspheres to 200g of n-hexane to obtain a dispersion. Apply a single-component acrylic resin adhesive (Shanghai Yuanbang Chemical Manufacturing Co., Ltd., type 2650A) to the cleaned and dried copper plate surface for semi-curing (60℃, 15min). Then spray the raspberry-shaped superhydrophobic composite microsphere dispersion onto the copper plate surface and dry it at 40℃ for 12h to fully cure it, thus obtaining a superhydrophobic coating.

[0073] Example 4 (1) Mix 10g of γ-mercaptopropyltrimethoxysilane, 30g of octadecyltrimethoxysilane and 200g of deionized water, and then stir at room temperature for 15min at a rate of 200 r / min; then add 0.1g of 25wt% ammonia water, react at 40℃ for 2h and then stop stirring. After filtration, washing and vacuum drying at 80℃ for 8h, mercapto-conjugated polysilsesquioxane microspheres are obtained.

[0074] (2) Mix 100g of deionized water, 0.1g of Trition X-100 and 0.1g of 25wt% ammonia water and stir at room temperature for 1h; control the system temperature at 40℃, then add 4g of vinyltriethoxysilane and 15g of methyltriethoxysilane, keep warm for 10h to obtain a vinyl conjugated polysilsesquioxane emulsion.

[0075] (3) Add 20g of mercapto-containing conjugated polysilsesquioxane microspheres and 2g of benzoin dimethyl ether photoinitiator to all the vinyl-containing conjugated polysilsesquioxane emulsions prepared in step (2). Stir mechanically at room temperature for 20min to disperse the microspheres evenly. Then, place the mixture under a 365nm UV lamp at 60℃ for 15min to complete the mercapto-ene click reaction. Finally, centrifuge, wash, and vacuum dry at 50℃ for 16h to obtain raspberry-like superhydrophobic composite microspheres.

[0076] (4) Add 15g of raspberry-shaped superhydrophobic composite microspheres to 200g of ethyl acetate to obtain a dispersion. Coat the surface of the cleaned and dried wood board with a single-component epoxy resin (Kinstar, K-3522 type) for semi-curing (80℃, 30min). Then spray the raspberry-shaped superhydrophobic composite microsphere dispersion onto the surface of the wood board and dry it at 80℃ for 4h to fully cure it, thus obtaining a superhydrophobic coating.

[0077] Comparative Example 1 Compared with Example 1, the only difference is that sodium dodecylbenzenesulfonate, an emulsifier, was not added in step (2), while the rest of the preparation process is the same as in Example 1.

[0078] Comparative Example 2 Compared with Example 1, the only difference is that in step (1), methyltrimethoxysilane is replaced by γ-mercaptopropyltrimethoxysilane in equal amounts; in step (2), methyltrimethoxysilane is replaced by vinyltrimethoxysilane in equal amounts, and the rest of the preparation process is the same as in Example 1.

[0079] Comparative Example 3 The microspheres prepared in Comparative Example 2 were immersed in an ethanol solution of 5 wt% methyltriethoxysilane, stirred at 40°C for 1 h for hydrophobic modification, and then vacuum dried at 80°C for 4 h for coating preparation. The coating preparation process was the same as in Example 1.

[0080] Comparative Example 4 Compared with Example 1, the only difference is that in step (3), no photoinitiator and ultraviolet light irradiation were used, and mechanical stirring was only performed for 20 minutes to make the two evenly dispersed. The rest of the preparation process is the same as in Example 1.

[0081] Performance testing Microstructure: The microstructure of the microspheres was observed using a Philips Nanosem 430 field emission scanning electron microscope from the Netherlands.

[0082] Coating wetting performance: The static water contact angle (WCA) and roll-off angle of the sample surface were tested at room temperature using a contact angle goniometer (DCA 35, Dataphysics, Germany). The water droplet size for the static water contact angle test was 2 μL, and the water droplet size for the roll-off angle test was 10 μL.

[0083] Abrasion resistance: Place 600-grit sandpaper with a 100-g weight on the coating surface, push it 10cm in one direction at a constant speed, and pull it back 10cm in the opposite direction at the same speed. Record this as one abrasion cycle. After 20 cycles, test the coating wetting performance.

[0084] Durability: The coating was placed in an outdoor environment for 6 months and subjected to natural climate conditions. The wetting properties of the coating were then tested.

[0085] Table 1 Performance test results of the coatings prepared in Examples 1-4 and Comparative Examples 1-4

[0086] Please see Figure 1 ,pass Figure 1 It can be seen that γ-mercaptopropyltrimethoxysilane and methyltrimethoxysilane are catalytically hydrolyzed and co-polymerized to form mercapto-containing conjugated polysilsesquioxane microspheres; in the presence of an emulsifier, vinyltrimethoxysilane and methyltrimethoxysilane are catalytically hydrolyzed and co-polymerized to form vinyl-containing conjugated polysilsesquioxane emulsions; under ultraviolet light initiation, the mercapto groups in the mercapto-containing conjugated polysilsesquioxane microspheres and the vinyl-containing conjugated polysilsesquioxane emulsion undergo mercapto-ene click reactions with vinyl groups to form covalent bonds, thus preparing raspberry-like superhydrophobic composite microspheres.

[0087] Please see Figure 2 ,pass Figure 2 As can be seen, the raspberry-like superhydrophobic composite microspheres prepared in Example 1 of this invention have a typical raspberry-like structure. These microspheres are regularly shaped with good sphericity. The core microspheres are concentrated around 3 μm in size, and their surfaces are densely and uniformly coated with a large number of uniformly sized nanospheres with a diameter of approximately 500 nm. These nanospheres are separated from each other without obvious aggregation or fusion, collectively forming a multi-level rough structure on the surface of the microspheres. Please refer to [link / reference]. Figure 3 ,pass Figure 3 As can be seen, the coating prepared in Example 1 of this invention has excellent hydrophobic properties, and the water droplets are quasi-spherical. Please refer to... Figure 4As shown in Table 1, the water contact angle of the coating is 163.5°, indicating a very high water contact angle and excellent superhydrophobic properties. This is mainly attributed to the construction of the raspberry-like high-roughness structure and the co-condensation of low surface energy alkoxysilanes. Furthermore, the test results in Table 1 show that after wear resistance testing and six months of outdoor placement, the coating prepared in Example 1 of this invention still exhibits superhydrophobic properties with a hydrophobic angle >150° and a roll-off angle <10°.

[0088] Please see Figure 5 ,pass Figure 5 It can be seen that the coating prepared in Example 2 of the present invention also has super repulsive force and low adhesion to water droplets; at the same time, as can be seen from the test results in Table 1, the coating prepared in Example 2 of the present invention has a hydrophobic angle of 165.9° and a roll-off angle of 2.3°, and still exhibits a superhydrophobic state after wear resistance test and outdoor placement for half a year.

[0089] Please see Figure 6 ,pass Figure 6 It can be seen that the coating prepared in Example 3 of the present invention also has excellent hydrophobicity to water droplets, and the water droplets exhibit a near-spherical state on the surface of the copper plate coating. At the same time, as can be seen from the test results in Table 1, the coating prepared in Example 3 of the present invention has a hydrophobic angle of 167.6° and a roll-off angle of 1.9°, and still exhibits a superhydrophobic state after wear resistance test and outdoor placement for half a year.

[0090] Please see Figure 7 ,pass Figure 7 It can be seen that the coating prepared in Example 4 of the present invention also has excellent hydrophobic properties; at the same time, as can be seen from the test results in Table 1, the hydrophobic angle of the coating prepared in Example 4 of the present invention is 161.2°, the roll-off angle is 3.8°, the hydrophobic angle is 153.2° and the roll-off angle is 6.2° after wear resistance test, and after being placed outdoors for half a year, the hydrophobic angle is 151.7° and the roll-off angle is 6.8°, all of which show a superhydrophobic state.

[0091] Please see Figure 8 ,pass Figure 8As can be seen, in Comparative Example 1, no emulsifier was used. The size of the vinyl-containing conjugated polysilsesquioxane microspheres prepared by direct hydrolysis-condensation of silicon monomers in aqueous solution was significantly increased. The size difference between them and the mercapto-containing conjugated polysilsesquioxane microspheres was not significant. It was impossible to construct a raspberry-like composite microsphere structure. The roughness of the microspheres decreased significantly, and the hydrophobic effect of the coating was also significantly reduced (Table 1). The reason is that, in the presence of emulsifiers, the silicone monomer oil phase is dispersed into the aqueous phase by shear forces such as mechanical stirring. Emulsifier molecules are rapidly adsorbed on the oil-water interface, forming a strong molecular film that effectively prevents the merger of droplets. These droplets, stabilized by the emulsifier and of uniform size, become tiny "reactors." Subsequently, polymerization or cross-linking reactions are initiated inside the droplets, "solidifying" the droplet shape to form solid microspheres. This greatly reduces the size and distribution range of vinyl-containing conjugated polysilsesquioxane microspheres, making the size difference between them and mercapto-containing conjugated polysilsesquioxane microspheres even greater, thus constructing a raspberry-like composite microsphere structure and obtaining a superhydrophobic coating.

[0092] Please refer to Table 1. In Comparative Example 2, instead of using low surface energy trimekoxysilane copolymerization, only γ-mercaptopropyltrimethoxysilane and vinyltrimethoxysilane were used. The hydrophobic effect of the prepared coating decreased sharply. The reason is that although a mercapto-ene click reaction occurred between the two microspheres and a raspberry-like micro-nano hierarchical rough structure was constructed, the surface energy of the vinyl group was higher than that of the methyl group, resulting in a poor hydrophobic effect of the coating.

[0093] Please refer to Table 1. The hydrophobic effect of the coating in Comparative Example 3 is similar to that in Example 1, exhibiting superhydrophobic properties. However, after wear resistance testing and six months of outdoor placement, the hydrophobic performance significantly decreased compared to Example 1. This is because the composite microspheres in Example 1 are prepared using low surface energy siloxane copolymerization, resulting in overall hydrophobic properties. Even with slight surface wear, the exposed material remains the same hydrophobic material, and its performance does not change abruptly, remaining very stable and uniform. In contrast, in Comparative Example 3, although it is also modified with a large amount of methyl groups, the hydrophobicity relies solely on a very thin monolayer on the surface. If this modified layer is scratched, worn, or subjected to high temperatures or prolonged ultraviolet radiation, the hydrophobicity is easily permanently lost.

[0094] Please refer to Table 1. In Comparative Example 4, the rough structure was constructed between the vinyl-containing conjugated polysilsesquioxane and the mercapto-containing conjugated polysilsesquioxane microspheres only through electrostatic attraction or van der Waals forces. The hydrophobic effect was somewhat inferior to that of Example 1. This may be because the physical bonding method used in Comparative Example 4 resulted in poor bonding between the mercapto-containing conjugated polysilsesquioxane microspheres and the vinyl-containing conjugated polysilsesquioxane, leading to a decrease in roughness. At the same time, since the two did not form a stable and strong covalent bond, the physically bonded raspberry-like microspheres had weak bonding force and poor mechanical stability. After the wear resistance test, the raspberry-like structure of the coating was severely damaged, resulting in insufficient roughness and a significant decrease in wear resistance.

[0095] Compared with the prior art, the beneficial effects of the present invention include: (1) By imitating the surface of lotus leaves, the present invention constructs a multi-level roughness combining micron and nanometer scales in the shape of raspberries. It has a high degree of structural hierarchy and complexity, which greatly improves the Cassie-Baxter state stability of the superhydrophobic surface and provides a key structural basis for realizing superhydrophobicity.

[0096] (2) The raspberry-like superhydrophobic microspheres of the present invention are mostly composed of low surface energy alkoxysilanes. The composite microspheres have intrinsic self-hydrophobicity and do not require any surface modification or alteration. Even if the surface is slightly worn, the exposed position still has hydrophobicity, and the performance is stable and uniform.

[0097] (3) In this invention, the mercapto-ene click reaction between the mercapto groups in the mercapto-containing conjugated polysilsesquioxane microspheres and the vinyl-containing conjugated polysilsesquioxane emulsions is initiated by ultraviolet light to form covalent bonds. Compared with physical adsorption such as hydrogen bonding, electrostatic attraction, and van der Waals forces, it has obvious advantages in strength and stability.

[0098] (4) The present invention can adjust the size and surface roughness of the raspberry-shaped composite microspheres by adjusting the amount of silicon monomer, emulsifier, reaction temperature, catalyst, etc., and can also adjust the hydrophobicity of the composite microspheres by adjusting the ratio between the copolymer silicon monomers to meet the product requirements of different places.

[0099] (5) The present invention can be used in conjunction with an adhesive. The composite microspheres can be simply sprayed onto the surface of a substrate that has been pre-coated with adhesive and semi-cured to prepare a superhydrophobic coating with strong wear resistance and durability.

[0100] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A raspberry-shaped superhydrophobic composite microsphere, characterized in that, include: The core microspheres and nanoparticles, wherein the nanoparticles are attached to the surface of the core microspheres via covalent bonds generated by a thiol-ene click chemistry reaction, constructing a raspberry-like heterostructure; wherein... The surface of the core microspheres is modified with thiol functional groups and / or alkenyl functional groups, and the surface of the nanoparticles is correspondingly modified with alkenyl functional groups and / or thiol functional groups. Furthermore, at least one of the surfaces of the core microspheres and the nanoparticles is modified with C1-C... 18 Alkyl and / or phenyl.

2. The raspberry-like superhydrophobic composite microspheres according to claim 1, characterized in that, The core microspheres are mercapto-conjugated polysilsesquioxane microspheres, and some or all of the remaining functional groups on the silicon atoms of their framework are independently bounded by C1-C2. 18 Alkyl or phenyl optional substitution; and / or, The nanoparticles are vinyl-conjugated polysilsesquioxane nanoparticles, and some or all of the remaining functional groups on their framework silicon atoms are independently bounded by C1-C2. 18 Alkyl or phenyl groups may be optionally substituted.

3. The raspberry-like superhydrophobic composite microspheres according to claim 1, characterized in that, The particle size ratio of the core microspheres to the nanoparticles is 1:(0.06-0.4); and / or, The core microspheres have a particle size of 2-5 μm, and the nanoparticles have a particle size of 300-800 nm.

4. The raspberry-like superhydrophobic composite microspheres according to claim 1, characterized in that, The core microspheres are synthesized by catalytic hydrolysis and co-condensation polymerization of mercaptosilicone monomers and a first low surface energy silicon monomer; wherein... The mercaptosilicone monomer includes C1-C 18 mercaptoalkyltrialkoxysilanes; and / or, The mercaptosilicone monomer includes C1-C 18 mercaptoalkyltrimethoxysilane, C1-C 18 One or more of mercaptoalkyltriethoxysilanes; and / or, The mercaptosilicone monomer includes γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, and C... 10 -C 18 Long-chain mercaptoalkyltrimethoxysilane, C 10 -C 18 One or more of long-chain mercaptoalkyltriethoxysilanes; and / or, The first low surface energy silicon monomer comprises C1-C 18 alkyl or phenyl-substituted trialkoxysilanes; and / or, The first low surface energy silicon monomer comprises C1-C 18 Alkyltrimethoxysilane, C1-C 18 One or more of alkyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane; and / or, The first low surface energy silicon monomer comprises one or more of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, octadecyltrimethoxysilane, and octadecyltriethoxysilane; and / or, The mass ratio of the mercaptosil monomer to the first low surface energy silicon monomer is 1:(3-13); and / or, The preparation process of the core microspheres includes: mixing the mercaptosilicone monomer, the first low surface energy silicon monomer, and the first water evenly, then adding the first ammonia water, and undergoing a first reaction to obtain mercapto-containing conjugated polysilsesquioxane microspheres; the mass fraction of the first ammonia water is 20%-30%; the mass ratio of the first water to the mercaptosilicone monomer + the first low surface energy silicon monomer and the first ammonia water is 100:(15-25):(0.05-0.2); the temperature of the first reaction is 20-40℃, and the time of the first reaction is 2-4h.

5. The raspberry-like superhydrophobic composite microspheres according to claim 1, characterized in that, The nanoparticles are synthesized by co-condensation polymerization of vinyl silicon monomer and a second low surface energy silicon monomer under emulsifying conditions via catalytic hydrolysis; wherein... The vinylsilicon monomer comprises a trialkoxysilane containing an ethylene-terminated group; and / or, The vinylsilicone monomer includes one or more of trimethoxysilanes containing ethylene-terminated groups and triethoxysilanes containing ethylene-terminated groups; and / or, The vinylsilane monomer includes one or more of vinyltrimethoxysilane and vinyltriethoxysilane; and / or, The second low surface energy silicon monomer includes C1-C 18 alkyl or phenyl-substituted trialkoxysilanes; and / or, The second low surface energy silicon monomer includes C1-C 18 Alkyltrimethoxysilane, C1-C 18 One or more of alkyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane; and / or, The second low surface energy silicon monomer includes one or more of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, octadecyltrimethoxysilane, and octadecyltriethoxysilane; and / or, The mass ratio of the vinyl silicon monomer to the second low surface energy silicon monomer is 1:(3-6); and / or, The emulsifier is one or more of sodium dodecylbenzenesulfonate, fatty alcohol polyoxyethylene ether, Triton X-100, and Tween 80; and / or, The preparation process of the nanoparticles includes: mixing the second water, the emulsifier, and the second ammonia water evenly, then adding the vinyl silicon monomer and the second low surface energy silicon monomer, and after a second reaction, obtaining a vinyl-containing conjugated polysilsesquioxane emulsion; the mass fraction of the second ammonia water is 20%-30%; the mass ratio of the second water, the emulsifier, and the second ammonia water is 100:(0.1-0.5):(0.05-0.2); the mass ratio of the vinyl silicon monomer + the second low surface energy silicon monomer to the second water is (15-25):100; the temperature of the second reaction is 20-40℃, and the time of the second reaction is 8-12h.

6. The raspberry-like superhydrophobic composite microspheres according to claim 5, characterized in that, The mass ratio of the vinyl-containing conjugated polysilsesquioxane emulsion to the mercapto-containing conjugated polysilsesquioxane microspheres is 100:(10-40).

7. A method for preparing raspberry-like superhydrophobic composite microspheres as described in any one of claims 1-6, characterized in that, Includes the following steps: Provide core microspheres and nanoparticles; The nanoparticles are attached to the surface of the core microspheres by covalent bonds generated by the thiol-ene click chemical reaction, forming a raspberry-like heterostructure and obtaining a raspberry-like superhydrophobic composite microsphere.

8. The method for preparing raspberry-like superhydrophobic composite microspheres according to claim 7, characterized in that, The nanoparticles are attached to the surface of the core microspheres via covalent bonds generated by a thiol-ene click chemical reaction, constructing a raspberry-like heterostructure. The steps to obtain raspberry-like superhydrophobic composite microspheres include: uniformly mixing a vinyl-containing conjugated polysilsesquioxane emulsion, thiol-containing conjugated polysilsesquioxane microspheres, and a photoinitiator, followed by a thiol-ene click reaction to obtain the raspberry-like superhydrophobic composite microspheres; wherein... The photoinitiator is one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, dimethyl benzoate, and 2,2-dimethoxy-2-phenylacetophenone; and / or, The mass ratio of the mercapto-containing conjugated polysilsesquioxane microspheres to the photoinitiator is 100:(1-10); and / or, The temperature of the thiol-ene click chemistry reaction is 50-70℃, and the time of the thiol-ene click chemistry reaction is 10-30 min; and / or, The mercapto-ene click chemistry reaction is carried out under ultraviolet light; and / or, The mercapto-ene click chemistry reaction is carried out under ultraviolet light, and the wavelength of the ultraviolet light is 300-400 nm.

9. An application of the raspberry-like superhydrophobic composite microspheres as described in any one of claims 1-6, characterized in that, The raspberry-shaped superhydrophobic composite microspheres are used to prepare superhydrophobic coatings.

10. The application of the raspberry-like superhydrophobic composite microspheres according to claim 9, characterized in that, The steps for applying the raspberry-shaped superhydrophobic composite microspheres to prepare a superhydrophobic coating include: The raspberry-shaped superhydrophobic composite microspheres are dispersed in a dispersion solvent, then coated onto a substrate surface and dried to form a superhydrophobic coating; and / or, The raspberry-shaped superhydrophobic composite microspheres and binder are dispersed in a dispersion solvent, then coated onto a substrate surface and completely cured to form a superhydrophobic coating; and / or, The raspberry-shaped superhydrophobic composite microspheres are dispersed in a dispersion solvent and then coated onto the surface of a substrate that has been pre-coated with an adhesive and semi-cured. After complete curing, a superhydrophobic coating is formed.

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