Pickering emulsion containing janus particles and its preparation method and application

Abstract

The present application relates to the technical field of functional coating materials, and particularly relates to a Pickering emulsion containing Janus particles and a preparation method and application thereof, the preparation method comprising the following steps: hydrophilic particles are subjected to a silanization reaction to obtain hydrophobic modified particles; a film-forming polymer is mixed with a solvent as an oil phase; the hydrophobic modified particles, the oil phase and an ionized water solution of a bonding compound are mixed, and after ultrasonic emulsification, a Pickering emulsion is obtained. In the present application, the hydrophobic modified particles are used as Pickering stabilizers, the ionized water solution of the bonding compound with both reactivity and bonding function is used as an aqueous phase, and the solvent containing a low-surface-energy film-forming polymer is used as an oil phase. In the process of high-shear emulsification, the hydrophobic modified particles migrate to the oil-water interface, the strong alkaline environment provided by the ionized water solution of the bonding compound hydrolyzes the hydrophobic layer on the side of the hydrophobic modified particles in contact with the aqueous phase, and the surface of the particles is in situ changed from isotropic hydrophobicity to hydrophilic / hydrophobic amphiphilic Janus structure.

Description

Technical Field

[0001] This invention relates to the field of functional coating materials technology, and in particular to a Pickering emulsion containing Janus particles, its preparation method, and its application. Background Technology

[0002] As a key encapsulation material for photovoltaic modules, the surface optical properties and environmental durability of photovoltaic glass directly affect the photoelectric conversion efficiency and service life of the modules. Statistics show that ordinary photovoltaic glass can cause a 15% to 30% decrease in actual module output power due to surface reflection loss and atmospheric dust pollution. Constructing a multifunctional coating on the surface of photovoltaic glass that combines high light transmittance, self-cleaning properties, and long-term weather resistance has become an effective technical approach to improve the power generation efficiency of photovoltaic systems and reduce operation and maintenance costs.

[0003] Pickering emulsions, a novel type of emulsion that stabilizes the oil-water interface solely through particles, have been widely studied in academia and industry due to their high stability, biocompatibility, and environmental friendliness. In recent years, platform technologies for applying Pickering emulsions to construct functional coatings have also attracted considerable attention. However, traditional hydrophobic particle-stabilized Pickering emulsions suffer from insufficient stability. Studies have shown that inorganic particle-stabilized Pickering emulsions often exhibit low stability and are prone to particle desorption, droplet coalescence, and phase separation under long-term static conditions or extreme environments (such as freeze-thaw cycles). Furthermore, coatings prepared from hydrophobic particle-stabilized Pickering emulsions rely primarily on physical adsorption for interfacial bonding with the glass substrate, lacking effective chemical bonding. This results in weak coating adhesion, making it difficult to meet the long-term reliability requirements of outdoor photovoltaic modules.

[0004] Janus amphiphilic particles exhibit significant advantages in stabilizing Pickering emulsions due to their unique hydrophilic / hydrophobic structure. The desorption energy of Janus particles at the oil-water interface is 3-4 orders of magnitude higher, enabling them to form a near-solid-state rigid interfacial film that fundamentally inhibits droplet coalescence. However, existing methods for preparing Janus particles generally suffer from complex processes and difficulty in scaling up. For example, reported methods for preparing Janus particles include seed emulsion polymerization, bipolar electrochemical methods, and two-phase interfacial assembly methods. These methods typically involve multi-step reactions, template removal, or precise control of conditions, resulting in long preparation cycles and high costs, thus limiting the large-scale application of Janus particles in the coating field.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a Pickering emulsion containing Janus particles, its preparation method and application, in order to solve the problems of complex Janus particle preparation process and insufficient stability of Pickering emulsion.

[0007] The technical solution of the present invention is as follows: A method for preparing a Pickering emulsion containing Janus particles, comprising the following steps: The silane coupling agent was mixed with hydrophilic particles and subjected to a silanization reaction to obtain hydrophobically modified particles. The film-forming polymer is mixed with a solvent to obtain an oil phase; The hydrophobic modified particles, the oil phase, and the ionic aqueous solution of the binder compound were mixed and then ultrasonically emulsified to obtain a Pickering emulsion containing Janus particles.

[0008] The method for preparing the Pickering emulsion containing Janus particles, wherein the silane coupling agent is selected from one or more of hexadecyltrimethoxysilane, dodecyltrimethoxysilane, dodecyltrimethoxysilane, perfluorodecyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, n-octyltriethoxysilane, octadecyltrichlorosilane, dimethyldichlorosilane, and hexamethyldisilazane; The amount of the silane coupling agent used is 5%-20% of the mass of the hydrophilic particles.

[0009] The method for preparing the Pickering emulsion containing Janus particles, wherein the silanization reaction is carried out at a temperature of 25 ℃-30 ℃ and for a time of 10 h-18 h.

[0010] The method for preparing the Pickering emulsion containing Janus particles, wherein the hydrophilic particles include one or more of SiO2, TiO2, ZnO, Al2O3, ZrO2, SiO2@TiO2 core-shell structured particles, polystyrene microspheres, and polymethyl methacrylate microspheres; The hydrophilic particles are surface-modified.

[0011] The method for preparing the Pickering emulsion containing Janus particles, wherein the film-forming polymer includes one or more of polydimethylsiloxane, modified polydimethylsiloxane, fluorocarbon resin, acrylic resin, and organosilicon modified resin. The fluorocarbon resin includes one or more of polyvinylidene fluoride and fluoroolefin-vinyl ether copolymers; The acrylic resin includes one or more of polymethyl methacrylate and polybutyl acrylate; The organosilicon-modified resin includes one or more of organosilicon-modified polyester and organosilicon-modified acrylate.

[0012] The method for preparing the Pickering emulsion containing Janus particles, wherein the solvent is one or more selected from decamethylcyclopentasiloxane, limonene, mandarin oil, tetrahydrofuran, ethyl acetate, toluene, n-hexane, n-heptane, cyclopentane, dimethyl carbonate, and propylene glycol methyl ether acetate. In the oil phase, the mass fraction of the film-forming polymer is 10%-15%.

[0013] The method for preparing the Pickering emulsion containing Janus particles, wherein the binder compound ionic aqueous solution comprises one or more of the following: sodium silicate ionic aqueous solution, sodium aluminate ionic aqueous solution, silica sol, hydrolysate of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, and tetraethyl orthosilicate hydrolysate. The concentration of the ionic aqueous solution of the binding compound is 15 wt.%-50 wt.%. The modulus of the aqueous ionic solution of the binding compound is 1.5-4; The volume ratio of the oil phase to the aqueous ionic solution of the binder compound is (8:2)-(5:5), and the mass fraction of the hydrophobic modified particles in the oil phase is 5 wt.%-20 wt.%.

[0014] The method for preparing the Pickering emulsion containing Janus particles, wherein the ultrasonic emulsification power is 60%-85% and the ultrasonic emulsification time is 1 min-10 min.

[0015] A Pickering emulsion containing Janus particles is prepared using the method for preparing the Pickering emulsion containing Janus particles.

[0016] Application of a Pickering emulsion containing Janus particles in a multifunctional coating for photovoltaic glass.

[0017] Beneficial Effects: This invention provides a Pickering emulsion containing Janus particles, its preparation method, and its application. The preparation method of the Pickering emulsion containing Janus particles includes the following steps: mixing a silane coupling agent with hydrophilic particles, and then performing a silanization reaction to obtain hydrophobically modified particles; mixing a film-forming polymer with a solvent to obtain an oil phase; mixing the hydrophobically modified particles, the oil phase, and an aqueous solution of a binding compound, and then performing ultrasonic emulsification to obtain the Pickering emulsion containing Janus particles. This invention uses hydrophobically modified particles as Pickering stabilizers, an aqueous solution of a binding compound with both reactive and adhesive functions as the aqueous phase, and a solvent containing a low surface energy film-forming polymer as the oil phase. During high-shear emulsification, the hydrophobically modified particles migrate to the oil-water interface. The strongly alkaline environment provided by the aqueous solution of the binding compound hydrolyzes the hydrophobic layer on the side of the hydrophobically modified particles in contact with the aqueous phase, causing the particle surface to transform from an isotropic hydrophobic in situ to a hydrophilic / hydrophobic amphiphilic Janus structure. This process integrates Janus particle preparation and Pickering emulsion stabilization into a single emulsification step, achieving in-situ construction of Janus particles and simultaneous stabilization of the interface. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the process flow for preparing a Pickering emulsion containing Janus particles according to the present invention. Figure 2 This is a characterization diagram of the water contact angle of the silanized silica particles in Example 1; Figure 3 This is a characterization diagram of the water contact angle of the silanized silica particles in Example 2; Figure 4 This is a characterization diagram of the water contact angle of the silanized titanium dioxide particles in Example 3; Figure 5 This is a graph showing the stability evaluation results of the Pickering emulsion containing Janus particles prepared in Example 1 at both the macroscopic and microscopic levels. Figure 6 Figures showing the surface performance test results of samples with different coatings; Figure 7 The image shows the light transmittance of the NOSPE coating in Example 1. Figure 8 The figure shows the performance data results of the coating self-cleaning effect in improving the photoelectric conversion efficiency of photovoltaic modules. Detailed Implementation

[0019] This invention provides a Pickering emulsion containing Janus particles, its preparation method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0021] In the field of photovoltaic glass coatings, while existing technologies have made some progress in improving light transmittance—for example, the high-transmittance anti-reflective coating developed by Flat Glass Group can improve photoelectric conversion efficiency by 5-8%—breakthroughs are still needed in the multifunctional integration (such as self-cleaning and superhydrophobicity) and long-term environmental durability of the coatings. Therefore, how to simultaneously achieve strong interfacial bonding, excellent hydrophobicity, and long-term weather resistance of the coating without sacrificing light transmittance remains the core challenge facing current technology.

[0022] Based on this, such as Figure 1 As shown, this invention provides a method for preparing a Pickering emulsion containing Janus particles, comprising the following steps: Step S10: Mix the silane coupling agent with the hydrophilic particles, and then perform a silanization reaction to obtain hydrophobically modified particles; Step S20: Mix the film-forming polymer with a solvent to obtain an oil phase; Step S30: The hydrophobic modified particles, the oil phase, and the ionic aqueous solution of the binder compound are mixed and ultrasonically emulsified to obtain a Pickering emulsion containing Janus particles.

[0023] In this embodiment, hydrophobic modified particles are used as Pickering stabilizers, an aqueous solution of a binding compound with both reactive and adhesive functions is used as the aqueous phase, and a solvent containing a low surface energy film-forming polymer is used as the oil phase. During high-shear emulsification, the hydrophobic modified particles migrate to the oil-water interface. The strongly alkaline environment provided by the aqueous solution of the binding compound hydrolyzes the hydrophobic layer on the side of the hydrophobic modified particles in contact with the aqueous phase, causing the particle surface to change from an isotropic hydrophobic in situ to a hydrophilic / hydrophobic amphiphilic Janus structure. This process integrates Janus particle preparation and Pickering emulsion stabilization into a single emulsification step, achieving in-situ construction of Janus particles and simultaneous stabilization of the interface.

[0024] Specifically, this invention uses an aqueous solution of a binder compound as both a reaction medium and a functional component. During the ultrasonic emulsification of the Pickering emulsion, the strongly alkaline environment of the binder compound's aqueous solution is utilized to selectively etch the hydrophobic modified particles at the interface, achieving in-situ transformation of the particles from isotropic hydrophobic to amphiphilic / hydrophobic Janus structures in one step. Janus particles are synthesized in-situ during emulsion formation, enabling the preparation of a highly stable Pickering emulsion in a single step. Furthermore, the aqueous solution of the binder compound not only selectively etches the silanized hydrophobic layer of the hydrophobic modified particles during emulsification to achieve Janus particle synthesis, but also acts as a chemical binder when the Pickering emulsion containing Janus particles is coated onto a photovoltaic glass substrate using a spraying process. During curing, it forms a Si-O-Si covalent network with the glass substrate and the hydrophilic surface of the Janus particles, constructing a multi-level chemical bonding interface, thus maximizing resource and efficiency utilization. This Pickering emulsion containing Janus particles forms a multifunctional coating on a glass substrate without the need for crosslinking agents. Curing and bonding are completed simultaneously, thereby significantly improving the adhesion of the coating.

[0025] In some embodiments, the silane coupling agent is selected from one or more of hexadecyltrimethoxysilane (HDTMS, C16), dodecyltrimethoxysilane (DTMS, C12), docosyltrimethoxysilane (C22), perfluorodecyltrimethoxysilane (FAS-17), phenyltrimethoxysilane (PTMS), diphenyldimethoxysilane, n-octyltriethoxysilane, octadecyltrichlorosilane, dimethyldichlorosilane, and hexamethyldisilazane. The aforementioned silane coupling agent generates silanol groups through the hydrolysis of the methoxy groups of silane molecules. These silanol groups then undergo a condensation reaction with the hydroxyl groups on the surface of the hydrophilic particles, forming a dense organic hydrophobic monolayer on the surface of the hydrophilic particles. This transforms the surface of the hydrophilic particles from hydrophilic to hydrophobic or even superhydrophobic. Furthermore, the surface energy of the modified particles is significantly reduced, making them less prone to adsorbing moisture. This greatly improves their dispersibility and stability, effectively preventing particle aggregation in nonpolar solvents, organic systems, or dry environments. In addition, different alkyl chain lengths and the introduction of phenyl and fluoroalkyl groups can impart differentiated surface properties to the particles.

[0026] In some embodiments, the amount of the silane coupling agent is 5%-20% of the mass of the hydrophilic particles. Controlling the amount of silane coupling agent within this range allows it to form a uniform and moderately dense hydrophobic modified layer on the surface of the hydrophilic particles. This effectively covers the hydrophilic hydroxyl groups on the particle surface, achieving a stable hydrophobic modification effect, while avoiding problems such as intermolecular self-agglomeration, micelle formation, or excess free silane residue caused by excessive coupling agent. Furthermore, within the above dosage range, the hydrolysis-condensation reaction is easier to control. The silane coupling agent is mainly grafted onto the particle surface in monolayer form, avoiding insufficient surface coverage and poor hydrophobicity due to insufficient dosage, and avoiding excessive cross-linking and aggregation between particles and decreased dispersibility due to excessive dosage. Simultaneously, it balances modification efficiency and cost, achieving a balance between the hydrophobicity, dispersion stability, and compatibility with the organic matrix of the modified particles.

[0027] In some embodiments, the amount of the silane coupling agent is, but is not limited to, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20% of the mass of the hydrophilic particles, but is not limited to integers.

[0028] In some embodiments, the silanization reaction is carried out at a temperature of 25°C-30°C for 10-18 hours. Under these conditions, the silanization reaction can be performed by hydrolyzing the methoxy groups of silane molecules to generate silanol groups, which then undergo a condensation reaction with the hydroxyl groups on the surface of the hydrophilic particles, forming a dense organic hydrophobic monolayer on the surface of the hydrophilic particles. This transforms the surface of the hydrophilic particles from hydrophilic to hydrophobic or even superhydrophobic.

[0029] In some embodiments, the temperature of the silanization reaction is, but not limited to, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, etc., and is not limited to an integer. The time of the silanization reaction is, but not limited to, 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, etc., and is not limited to an integer.

[0030] In some embodiments, the hydrophilic particles include, but are not limited to, one or more of SiO2, TiO2, ZnO, Al2O3, ZrO2, SiO2@TiO2 core-shell structured particles, polystyrene (PS) microspheres, and polymethyl methacrylate (PMMA) microspheres. They can also be metal oxide particles and other microspheres that conform to the requirements of Pickering emulsion stabilizer particles. After silanization modification, the above-mentioned hydrophilic particles can be used as Pickering stabilizers, and after mixing with the aqueous and oil phases, they can act as Pickering stabilizers.

[0031] In some embodiments, the hydrophilic particles undergo surface modification. Surface modification of the hydrophilic particles before silanization can improve the grafting efficiency and uniformity of the subsequent silane coupling agent.

[0032] In some embodiments, the film-forming polymer includes one or more of polydimethylsiloxane (PDMS), modified polydimethylsiloxane, fluorocarbon resin, acrylic resin, and organosilicon modified resin.

[0033] In some embodiments, the fluorocarbon resin includes one or more of polyvinylidene fluoride (PVDF) and fluoroolefin-vinyl ether copolymer (FEVE).

[0034] In some embodiments, the acrylic resin includes one or more of polymethyl methacrylate (PMMA) and polybutyl acrylate (PBA).

[0035] In some embodiments, the silicone-modified resin includes one or more of silicone-modified polyester and silicone-modified acrylate.

[0036] Specifically, by using the above-mentioned film-forming polymer dissolved in a solvent as the oil phase, and with the addition of an aqueous solution of a binding compound that has both reactive and adhesive functions as the aqueous phase, the hydrophobic modified particles can migrate to the oil-water interface during high-shear emulsification. The strongly alkaline environment provided by the aqueous solution of the binding compound hydrolyzes the hydrophobic layer on the side of the hydrophobic modified particles that is in contact with the aqueous phase, causing the particle surface to change from an isotropic hydrophobic in situ to a hydrophilic / hydrophobic amphiphilic Janus structure.

[0037] In some embodiments, the solvent is one or more selected from, but not limited to, decamethylcyclopentasiloxane (D5), limonene, mandarin oil, tetrahydrofuran, ethyl acetate, toluene, n-hexane, n-heptane, cyclopentane, dimethyl carbonate, and propylene glycol methyl ether acetate. These solvents help dilute the film-forming polymer, improving the leveling properties of the coating formed in subsequent steps.

[0038] In some embodiments, the mass fraction of the film-forming polymer in the oil phase is 10%-15%. By controlling the mass fraction of the film-forming polymer within the above range, the resulting Pickering emulsion containing Janus particles, when used as a coating material, exhibits good leveling properties, and the mass fraction of the film-forming polymer can be adjusted according to the actual requirements for leveling effect.

[0039] In some embodiments, the mass fraction of the film-forming polymer in the oil phase is, but not limited to, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, etc., and is not limited to integers.

[0040] In some embodiments, the binder compound ionic aqueous solution includes one or more of the following: sodium silicate ionic aqueous solution, sodium aluminate ionic aqueous solution, silica sol, hydrolysate of γ-aminopropyltriethoxysilane (KH550) and γ-glycidoxypropyltrimethoxysilane (KH560), and tetraethyl orthosilicate (TEOS) hydrolysate. The alkaline effect of the above-mentioned binder compound ionic aqueous solution can etch the hydrophobic layer on the surface of the hydrophobic modified particles, restoring their original hydrophilic properties.

[0041] Specifically, the aforementioned binder compound ionic aqueous solution can simultaneously serve as a reaction medium and a functional component. During the ultrasonic emulsification process of the Pickering emulsion, the strongly alkaline environment of the binder compound ionic aqueous solution is used to selectively etch the hydrophobic modified particles at the interface, achieving in-situ transformation of the particles from isotropic hydrophobic to amphiphilic / hydrophobic Janus structures in one step. Janus particles are synthesized in-situ during the emulsion formation process, enabling the preparation of highly stable Pickering emulsions in a single step. Furthermore, the binder compound ionic aqueous solution not only selectively etches the silanized hydrophobic layer of the hydrophobic modified particles during emulsification to achieve Janus structure synthesis, but also acts as a chemical binder when the Pickering emulsion containing Janus particles is coated onto a photovoltaic glass substrate using a spraying process. During curing, it forms a Si-O-Si covalent bond network with the glass substrate and the hydrophilic surface of the Janus particles, constructing a multi-level chemical bonding interface, thus maximizing the utilization of resources and efficiency.

[0042] In some embodiments, the concentration of the ionic aqueous solution of the binding compound is 15 wt.%-50 wt.%.

[0043] In some embodiments, the modulus of the ionic aqueous solution of the binding compound is 1.5-4.

[0044] Specifically, by controlling the concentration and modulus of the binder compound ionic aqueous solution within the above-mentioned range, the alkalinity of the binder compound ionic aqueous solution can be used to etch the hydrophobic layer on the surface of the hydrophobic particles, thereby restoring their original hydrophilic properties.

[0045] In some embodiments, the concentration of the ionic aqueous solution of the binding compound is, but not limited to, 15 wt.%, 18 wt.%, 20 wt.%, 23 wt.%, 25 wt.%, 28 wt.%, 30 wt.%, 32 wt.%, 35 wt.%, 37 wt.%, 39 wt.%, 40 wt.%, 42 wt.%, 45 wt.%, 48 wt.%, 50 wt.%, but not limited to integers.

[0046] In some embodiments, the volume ratio of the oil phase to the aqueous ionic solution of the binder compound is (8:2)-(5:5), and the mass fraction of the hydrophobic modified particles in the oil phase is 5wt%-20wt%.

[0047] In some embodiments, the ultrasonic emulsification power is 60%-85%, and the ultrasonic emulsification time is 1 min-10 min. By controlling the ultrasonic emulsification power and time within the above range, the hydrophobic modified particles can be self-assembled at the oil-water interface through the action of sharp ultrasound.

[0048] In some embodiments, the power of the ultrasonic emulsification is, but not limited to, 60%, 61%, 62%, 65%, 66%, 68%, 70%, 72%, 75%, 78%, 80%, 82%, 83%, 84%, or 85%, but is not limited to integers. The time of the ultrasonic emulsification is, but not limited to, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, or 10 min, but is not limited to integers.

[0049] In some embodiments, the Pickering emulsion containing Janus particles may be, but is not limited to, an oil-in-water (O / W) type Pickering emulsion, a water-in-oil (W / O) type Pickering emulsion, a bicontinuous phase emulsion, a W / O / W or O / W / O type multiple Pickering emulsion, or a conventional emulsion formed with the assistance of surfactants.

[0050] In some embodiments, the aqueous solution of the binder compound can be compounded with sodium hydroxide to adjust the pH and adjust the alkalinity, thereby controlling the etching rate and the degree of Janus formation.

[0051] In some embodiments, the aqueous solution of the binder compound can be compounded with borax, and the introduction of boron can form a borosilicate network, thereby improving the thermal stability and chemical durability of the final coating.

[0052] In addition, the present invention also provides a Pickering emulsion containing Janus particles, which is prepared using the method for preparing the Pickering emulsion containing Janus particles.

[0053] In this embodiment, the Pickering emulsion containing Janus particles prepared by the above preparation method can be used to stabilize the two-phase interface of the Pickering emulsion and construct a nanostructure on the coating surface. In addition, during the ultrasonic emulsification process of the Pickering emulsion, the strongly alkaline binder compound ionic aqueous solution can provide an alkaline environment to hydrolyze the hydrophobic groups of the hydrophobic modified particles to achieve the Janus amphiphilic structure.

[0054] Finally, the present invention also provides the application of a Pickering emulsion containing Janus particles in a multifunctional coating for photovoltaic glass.

[0055] In this embodiment, the Pickering emulsion containing Janus particles is applied to a multifunctional coating for photovoltaic glass. The Pickering emulsion can be coated into a film using a coating process. The film-forming polymer is used to achieve the leveling and film-forming properties of the coating. The particles and the film-forming polymer work together to form a hydrophobic structure of a composite wetting model, which allows water droplets to remain spherical on the coating surface and roll off quickly, achieving a lotus leaf-like self-cleaning effect. Meanwhile, the strongly alkaline binder compound provides adhesion between the particles and the glass substrate during coating curing, achieving long-term mechanical and environmental stability of the coating.

[0056] Specifically, the Pickering emulsion containing Janus particles was sprayed onto a photovoltaic glass substrate to form a film, which was then dried and cured to form a multifunctional coating. Due to the hydrophobic side of the Janus particles and the low surface energy of the film-forming polymer, the contact angle of the resulting coating surface was significantly better than that of the original glass (121.25°), achieving excellent self-cleaning effect. During the curing process, the adhesive compound ionic aqueous solution, acting as a chemical binder, utilized its own dehydration condensation to form siloxane bonds (Si-O-Si) with the siloxane bonds on the glass substrate surface through a condensation reaction. These bonds then crosslinked with the siloxane bonds on the hydrophilic side of the Janus particles, constructing a multi-level chemical bonding network spanning from the nanoscale to the macroscale, endowing the coating with excellent mechanical strength and environmental durability. Furthermore, the intrinsic refractive index of the selected adhesive compound ionic aqueous solution was highly matched with that of the particles and the low surface energy film-forming polymer, fundamentally avoiding interfacial light scattering and achieving high light transmittance of the coating, resulting in near-zero light transmittance loss from the glass substrate.

[0057] In some embodiments, for example, when the adhesive compound aqueous solution is a sodium silicate aqueous solution, the dehydration condensation reaction that occurs during the curing process of sodium silicate simultaneously generates a Si-O-Si covalent network with the silanol groups on the glass substrate surface and the hydrophilic side of the Janus particles, achieving the construction of an integrated chemical bonding interface in a single curing step. Furthermore, this method requires no crosslinking agent, and curing and bonding are completed simultaneously, thereby significantly improving the adhesion of the coating.

[0058] In some embodiments, the method for preparing the multifunctional coating of photovoltaic glass includes the steps of: coating a Pickering emulsion containing Janus particles onto the surface of photovoltaic glass using a coating process; and then curing the emulsion to obtain the multifunctional coating of photovoltaic glass.

[0059] In some embodiments, the coating process includes, but is not limited to, one of spraying, spin coating, roll coating, and slot coating.

[0060] In some embodiments, the curing temperature is 60 ℃-150 ℃ and the curing time is 10 min-1200 min; applying the emulsion coating to the glass substrate surface to form a film and then curing it at high temperature helps to accelerate the curing process.

[0061] Specifically, the photovoltaic glass multifunctional coating prepared using the Pickering emulsion containing Janus particles has a light transmittance ≥90% and a water contact angle ≥120°. Furthermore, after undergoing 100 mechanical friction cycles, 100 tape peel tests, high and low temperature cycles from -35 ℃ to 100 ℃, and 60 days of 365 nm UVA irradiation, the decrease in both the water contact angle and light transmittance is less than 2%.

[0062] In some embodiments, the multifunctional coating on the photovoltaic glass exhibits excellent self-cleaning and transparency, making it suitable for photovoltaic modules, including but not limited to photovoltaic glass cover coatings and photovoltaic glass anti-reflective coatings. Furthermore, the present invention relates to coating application fields including but not limited to automotive glass, architectural glass, optical devices, flexible devices, and the like.

[0063] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0064] Example 1 This embodiment provides a Pickering emulsion containing Janus particles, and the emulsion is sprayed to form a glass coating, as detailed below: PDMS was dissolved in decamethylcyclopentasiloxane (D5) at a ratio of 10 wt.% as the oil phase. Octadecyltrichlorosilane-modified silica (SiO2@OTS) was added to the oil phase, followed by ultrasonication and dispersion until homogeneous. The mass fraction of SiO2@OTS in the oil phase was 5 wt.%. A sodium silicate aqueous solution with a concentration of 15 wt.% and a modulus of 2 was added at a volume ratio of oil phase to water phase of 8:2. The mixture was then thoroughly emulsified by intermittent ultrasonication with a probe at a power of 60% for 5 min. During this process, a Pickering emulsion containing Janus particles was synthesized in situ.

[0065] Pickering emulsion containing Janus particles was sprayed onto pure silica glass (photovoltaic glass) to form a film, and the coating was cured by blowing at 60°C for 3 hours to obtain a glass coating (NOSPE coating) with transparent and self-cleaning effects.

[0066] Example 2 This embodiment provides a Pickering emulsion containing Janus particles, and the emulsion is sprayed to form a glass coating, as detailed below: PDMS was dissolved in decamethylcyclopentasiloxane (D5) at a ratio of 10 wt.% as the oil phase. Dimethyldichlorosilane-modified silica (SiO2@DMDCS) was added to the oil phase, followed by ultrasonication and dispersion until homogeneous. The mass fraction of SiO2@DMDCS in the oil phase was 5 wt%. A sodium silicate aqueous solution with a concentration of 15 wt.% and a modulus of 2 was added at a volume ratio of oil phase to aqueous phase of 8:2. The mixture was then thoroughly emulsified by intermittent ultrasonication with a probe at a power of 60% for 5 min. During this process, a Pickering emulsion containing Janus particles was synthesized in situ.

[0067] Pickering emulsion containing Janus particles was sprayed onto pure silica glass (photovoltaic glass) to form a film, and the coating was cured by blowing at 60 °C for 3 h to obtain a glass coating with transparent and self-cleaning effects.

[0068] Example 3 This embodiment provides a Pickering emulsion containing Janus particles, and the emulsion is sprayed to form a glass coating, as detailed below: PDMS was dissolved in decamethylcyclopentasiloxane (D5) at a ratio of 10 wt.% as the oil phase. Titanium dioxide (TiO2@HDMS) in hexamethyldisilazane was added to the oil phase and then ultrasonically dispersed until homogeneous, with the TiO2@HDMS mass fraction in the oil phase being 5 wt%. A sodium aluminate aqueous solution with a concentration of 15 wt.% and a modulus of 2 was added at a volume ratio of oil phase to aqueous phase of 8:2. The mixture was then thoroughly emulsified by intermittent ultrasonication using a probe at a power of 60% for 5 minutes. During this process, a Pickering emulsion containing Janus particles was synthesized in situ.

[0069] Pickering emulsion containing Janus particles was sprayed onto pure silica glass (photovoltaic glass) to form a film, and the coating was cured by blowing at 60 °C for 3 h to obtain a glass coating with transparent and self-cleaning effects.

[0070] The water droplet wetting behavior of the surface of hydrophilic particle tablets modified with different silane coupling agents in Examples 1-3 was compared. The water contact angles of the surface of the hydrophilic particle tablets modified with different silane coupling agents in Examples 1-3 are as follows: Figure 2 , Figure 3 and Figure 4As shown, the wettability of the particle surface changed significantly after modification. Among them, OTS, with its long alkyl chain and highly active chlorosilane groups, formed a dense and ordered self-assembled monolayer on the SiO2 surface, exhibiting excellent superhydrophobic properties with a contact angle of 153.4°. Its hydrophobic effect is significantly better than that of the HDMS (94.3°) and DMDCS (135.4°) modified systems.

[0071] The stability of the Pickering emulsion containing Janus particles prepared in Example 1 was evaluated at both the macroscopic and microscopic levels, and the results are as follows: Figure 5 As shown, where Figure 5 In the table, (a) represents macroscopic static stability, (b) represents macroscopic freeze-thaw stability, (c) represents particle size distribution of the emulsion after ultrasonic emulsification, (d) represents particle size distribution of the emulsion after standing for 60 days, and (e) represents particle size distribution of the emulsion after freeze-thaw.

[0072] It can be seen that, as Figure 5 As shown in (a), the emulsion maintained a uniform macroscopic morphology after standing for 60 days, without obvious phase separation, precipitation, or aggregation, indicating good long-term storage stability. From a microscopic particle size perspective, compared to the initial emulsified state (… Figure 5 Compared to (c) in the middle, after standing for 60 days ( Figure 5 The key particle size parameters of the (d) emulsion showed very little change, with the mean increasing slightly from 870.3 nm to 892 nm. d 90 The nm diameter increased from 978 nm to 993 nm, an increase of only about 1.5%. This subtle change reflects that the Ostwald ripening and aggregation behavior between droplets was effectively suppressed during long-term standing. The fundamental reason is that the SiO2@OTS particles form a dense solid particle layer with steric hindrance at the oil-water interface. This physical barrier significantly hinders the mass transfer and fusion between droplets, giving the emulsion excellent long-term standing stability.

[0073] Freeze-thaw cycling is an important method for evaluating the resistance of emulsions to extreme physical stress. During this process, the formation and growth of ice crystals can cause strong mechanical impact on the interfacial film, which traditional emulsions often cannot withstand, leading to demulsification. To further verify the stability of the emulsion under harsh conditions, its performance after freeze-thaw cycling was tested. The results are as follows: Figure 5 As shown in (b) and (e), the emulsion can still be restored to a homogeneous state after circulation treatment, with no obvious demulsification or stratification, and the micro-particle size also does not change significantly.

[0074] The hydrophobic properties of the original glass, pure PDMS film, and glass coating (NOSPE coating) prepared in Example 1 were visually compared by water droplet contact angle. The surface performance test results of the different coating samples are as follows: Figure 6 As shown, where Figure 6 In the image, (a) is a blank glass substrate, (b) is a pure PDMS film, and (c) is a Pickering emulsion coating; it can be seen that, as Figure 6 As shown in (a), the contact angle of the original glass surface is only 4.56°, exhibiting hydrophilic properties. This is mainly attributed to its surface being rich in silanol groups (-Si-OH), and the high surface energy causes water droplets to spread rapidly. In contrast, as... Figure 6 As shown in (b), the pure PDMS film exhibits a contact angle of 98.88°, demonstrating typical hydrophobic behavior. This is because PDMS, as a low surface energy organosilicon polymer, has methyl (-CH3) functional groups on its surface that dominate its hydrophobic properties. Meanwhile, NOSPE coatings constructed based on the Pickering emulsion strategy, such as... Figure 6 As shown in (c), by synergistically constructing a coating structure with Janus particles and sodium silicate, superior hydrophobic properties are achieved, with the contact angle increased to 121.25°. This coating, using Pickering emulsion as a template, forms a micro-nano hierarchical rough structure composed of SiO2@OTS particles and a PDMS film after curing. This structure effectively traps air, allowing water droplets to primarily contact the air, thereby significantly reducing the solid-liquid contact area. Based on a low surface energy chemical composition, it approaches the state described by the Cassie-Baxter model, achieving a significant increase in the contact angle.

[0075] The light transmittance of the NOSPE coating in Example 1 was demonstrated through both intuitive comparison and quantitative testing. The results are as follows: Figure 7 As shown. By comparing digital photographs of untreated glass and NOSPE-coated glass under the same conditions, and combining this with transmittance data under different test conditions, the light transmission characteristics of the coating can be intuitively reflected. Figure 7 As shown in the comparison of the light transmittance photographs in (a), after applying the NOSPE coating, the glass sample still maintains a light transmittance appearance similar to the original glass. According to the application requirements of photovoltaic glass (3.2 mm ultra-clear patterned glass standard), the light transmittance must be greater than 90% to ensure efficient sunlight incidence. Figure 7 The transmittance test results in (b) show that, within the wavelength range of 200-1100 nm (corresponding to the 300-1100 nm high-response range of crystalline silicon cells in the solar spectrum), the NOSPE coating maintains a transmittance of more than 90% throughout the long wavelength range and is uniformly distributed, meeting the basic requirements of photovoltaic modules for light capture efficiency.

[0076] The Pickering emulsion containing Janus particles from Example 1 was coated onto the surface of a photovoltaic module. Its protective effect on photoelectric performance under actual operating conditions was evaluated. Performance data on the coating's self-cleaning effect in improving the photoelectric conversion efficiency of the photovoltaic module are as follows: Figure 8 As shown.

[0077] After simulated pollution, the photovoltaic output of both the original glass module and the module coated with NOSPE showed a significant decrease. The short-circuit current density (JSC) of the original glass module plummeted to 13.84 mA·cm⁻¹. -2 The photoelectric conversion efficiency (PCE) dropped significantly to 9.80%, a loss of 42.0%; while the JSC of the NOSPE-coated module decreased to 14.66 mA·cm⁻¹. -2 The PCE was 10.37%, further confirming the significant impact of dust and sand pollution on photovoltaic efficiency. After cleaning, the original glass module... J sc It recovered to 19.03 mA·cm -2 The PCE level rebounded to 13.60%, with a recovery rate of only 80.5%, indicating that ordinary hydrophilic glass surfaces are difficult to completely remove contaminants during water rinsing, and residual stains cause continuous optical obstruction. In contrast, NOSPE-coated components... J sc It recovered to 24.86 mA·cm -2 The PCE rebounded to 17.93%, with a recovery rate of 98.6%, demonstrating excellent easy-to-clean performance.

[0078] In summary, this invention provides a Pickering emulsion containing Janus particles, its preparation method, and its application. The preparation method of the Pickering emulsion containing Janus particles includes the following steps: mixing a silane coupling agent with hydrophilic particles, and then performing a silanization reaction to obtain hydrophobically modified particles; mixing a film-forming polymer with a solvent to obtain an oil phase; mixing the hydrophobically modified particles, the oil phase, and an aqueous solution of a binding compound, and then performing ultrasonic emulsification to obtain the Pickering emulsion containing Janus particles. This invention uses hydrophobically modified particles as Pickering stabilizers, an aqueous solution of a binding compound with both reactive and adhesive functions as the aqueous phase, and a solvent containing a low surface energy film-forming polymer as the oil phase. During high-shear emulsification, the hydrophobically modified particles migrate to the oil-water interface. The strongly alkaline environment provided by the aqueous solution of the binding compound hydrolyzes the hydrophobic layer on the side of the hydrophobically modified particles in contact with the aqueous phase, causing the particle surface to transform from an isotropic hydrophobic in situ to a hydrophilic / hydrophobic amphiphilic Janus structure. This process integrates Janus particle preparation and Pickering emulsion stabilization into a single emulsification step, achieving in-situ construction of Janus particles and simultaneous stabilization of the interface.

[0079] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a Pickering emulsion containing Janus particles, characterized in that, Including the following steps: The silane coupling agent was mixed with hydrophilic particles and subjected to a silanization reaction to obtain hydrophobically modified particles. The film-forming polymer is mixed with a solvent to obtain an oil phase; The hydrophobic modified particles, the oil phase, and the ionic aqueous solution of the binder compound were mixed and then ultrasonically emulsified to obtain a Pickering emulsion containing Janus particles.

2. The method for preparing Pickering emulsion containing Janus particles according to claim 1, characterized in that, The silane coupling agent is selected from one or more of the following: hexadecyltrimethoxysilane, dodecyltrimethoxysilane, dodecyltrimethoxysilane, perfluorodecyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, n-octyltriethoxysilane, octadecyltrichlorosilane, dimethyldichlorosilane, and hexamethyldisilazane. The amount of the silane coupling agent used is 5%-20% of the mass of the hydrophilic particles.

3. The method for preparing Pickering emulsion containing Janus particles according to claim 1, characterized in that, The silanization reaction is carried out at a temperature of 25 ℃-30 ℃ and for a time of 10 h-18 h.

4. The method for preparing Pickering emulsion containing Janus particles according to claim 1, characterized in that, The hydrophilic particles include one or more of SiO2, TiO2, ZnO, Al2O3, ZrO2, SiO2@TiO2 core-shell structured particles, polystyrene microspheres, and polymethyl methacrylate microspheres; The hydrophilic particles are surface-modified.

5. The method for preparing Pickering emulsion containing Janus particles according to claim 1, characterized in that, The film-forming polymer includes one or more of polydimethylsiloxane, modified polydimethylsiloxane, fluorocarbon resin, acrylic resin, and organosilicon modified resin. The fluorocarbon resin includes one or more of polyvinylidene fluoride and fluoroolefin-vinyl ether copolymers; The acrylic resin includes one or more of polymethyl methacrylate and polybutyl acrylate; The organosilicon-modified resin includes one or more of organosilicon-modified polyester and organosilicon-modified acrylate.

6. The method for preparing Pickering emulsion containing Janus particles according to claim 1, characterized in that, The solvent is one or more selected from decamethylcyclopentasiloxane, limonene, mandarin oil, tetrahydrofuran, ethyl acetate, toluene, n-hexane, n-heptane, cyclopentane, dimethyl carbonate, and propylene glycol methyl ether acetate. In the oil phase, the mass fraction of the film-forming polymer is 10%-15%.

7. The method for preparing Pickering emulsion containing Janus particles according to claim 1, characterized in that, The binding compound ionic aqueous solution includes one or more of the following: sodium silicate ionic aqueous solution, sodium aluminate ionic aqueous solution, silica sol, hydrolysate of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, and tetraethyl orthosilicate hydrolysate. The concentration of the ionic aqueous solution of the binding compound is 15 wt.%-50 wt.%. The modulus of the aqueous ionic solution of the binding compound is 1.5-4; The volume ratio of the oil phase to the ionic aqueous solution of the binder compound is (8:2)-(5:5), and the mass fraction of the hydrophobic modified particles in the oil phase is 5 wt.%-20 wt.%.

8. The method for preparing Pickering emulsion containing Janus particles according to claim 1, characterized in that, The power of the ultrasonic emulsification is 60%-85%, and the ultrasonic emulsification time is 1 min-10 min.

9. A Pickering emulsion containing Janus particles, characterized in that, It is prepared using the Pickering emulsion containing Janus particles as described in any one of claims 1-8.

10. The application of a Pickering emulsion containing Janus particles as described in claim 9 in a multifunctional coating for photovoltaic glass.

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