Surface-modified cesium tungsten bronze nanomaterials, methods of making and using the same

Abstract

The application belongs to the field of nanomaterials, and particularly relates to a surface-modified cesium tungsten bronze nanomaterial and a preparation method and application thereof. The preparation method is as follows: during nanometer grinding of a cesium tungsten bronze slurry, a hydrolysis-condensation reaction of a coupling agent is triggered synchronously, so that the coupling agent is loaded in situ on the surface of particles, thereby realizing coupling of 'particle size refinement / dispersion' and'surface passivation / hydrophobation' in one-step process. The transparent heat-insulating film prepared by compounding the cesium tungsten bronze nanomaterial prepared by the application with polyvinyl butyral (PVB) has a near-infrared shielding rate of 94.6% and an ultraviolet shielding rate of 99.2% under the condition that the visible light transmittance at 550 nm is greater than 70%. After 60 days of 'double 85' (temperature 85 DEG C, humidity 85%RH) accelerated aging, the near-infrared shielding performance of the cesium tungsten bronze film modified by the silane coupling agent attenuates by less than 2.0%, which is significantly better than that of the unmodified cesium tungsten bronze sample (12.8%), and the modified cesium tungsten bronze film exhibits excellent service stability.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials, and in particular relates to a cesium tungsten bronze nanomaterial. Background Technology

[0002] Cesium tungsten bronze (chemical formula Cs) x WO3 (0 < x ≤ 0.33) is a class of non-stoichiometric tungsten oxide materials with a hexagonal tungsten bronze structure. Its crystal structure consists of a three-dimensional framework formed by [WO6] octahedra connected by shared vertices. Cs + Ions are embedded in hexagonal channels along the c-axis. Due to Cs + The free electrons introduced by doping lead to partial W 6+ Restored to W 5+ / W 4+ Cs x WO3 nanomaterials exhibit strong localized surface plasmon resonance and small polaron absorption, giving them excellent light absorption performance in the 780-2500 nm near-infrared region, while maintaining high transmittance in the visible light region.

[0003] However, Cs 0.32 WO3 is prone to surface-related performance degradation in humid / heated / light-exposed environments: mechanical polishing may cause surface amorphization and defect enrichment; when compounded with organic resins, moisture / ultraviolet light may induce H x WO3 and other reaction pathways lead to performance degradation; the evolution of surface oxygen vacancies and valence states may be accompanied by Cs. + Migration / precipitation further reduces stability. Therefore, suppressing water vapor / oxygen penetration and surface reactions through mild and scalable surface passivation methods is key to improving its engineering applicability.

[0004] Existing research often employs coatings such as SiO2 and Al2O3 to construct core-shell structures to improve weather resistance. Patent CN107513293A (prior reference document) discloses a modification approach involving the addition of coupling agents, infrared absorbers, and ultraviolet absorbers to cesium tungsten bronze powder, aiming to address the issue of UV discoloration in optical heat-insulating transparent materials. However, the method employed involves a conventional multi-step process of "grinding—reaction coating—separation and washing—redispersion—composite," resulting in a long process chain and significant challenges in scale-up and consistency control. Furthermore, existing technologies utilize ball milling to process Cs... x When WO3 powder is dispersed to the nanoscale, it often faces problems such as particle agglomeration, uneven particle size distribution, and oxidative degradation caused by exposure of surface active groups. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a surface-modified cesium tungsten bronze nanomaterial, its preparation method, and its applications.

[0006] The technical solution of this invention is implemented as follows:

[0007] This invention provides a surface-modified cesium tungsten bronze nanomaterial, comprising cesium tungsten bronze nanoparticles and a hydrophobic layer loaded on the surface of the particles; the hydrophobic layer is formed by an in-situ hydrolysis-condensation reaction of a coupling agent having hydrophobic functional groups; the particle size of the cesium tungsten bronze nanomaterial is 5-50 nm, and its near-infrared blocking performance decreases by less than 5% after aging at 85 °C and 85%RH for 60 days.

[0008] The chemical formula of the cesium tungsten bronze nanoparticles is Cs. x WO3, wherein 0.2 ≤ x ≤ 0.33, preferably 0.32 ≤ x ≤ 0.33. Cesium tungsten bronze has a hexagonal tungsten bronze crystal structure with space group P63 / mcm.

[0009] Furthermore, the hydrophobic layer is formed by an in-situ hydrolysis-condensation reaction of a coupling agent with hydrophobic functional groups on the surface of cesium tungsten bronze particles. The coupling agent is selected from one or more of silane coupling agents, titanate coupling agents, and aluminate coupling agents. The silane coupling agents include, but are not limited to: dimethyldimethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, n-octyltriethoxysilane, dodecyltriethoxysilane, tridecafluorooctyltrimethoxysilane, KH550 (γ-aminopropyltriethoxysilane), or KH560 (γ-glycidoxypropyltrimethoxysilane), etc. The hydrophobic functional groups include alkyl chains (such as methyl, octyl, dodecyl), fluoroalkyl chains, etc. These hydrophobic groups can effectively block the contact between water molecules and the surface of cesium tungsten bronze, inhibiting W 5+ Oxidation and the expansion of surface defects.

[0010] Furthermore, the molar ratio of Si, Ti, or Al in the coupling agent to W in the cesium tungsten bronze is 0.02-0.50:1, preferably 0.05-0.30:1. This ratio range ensures the formation of a continuous, dense, and moderately thick hydrophobic layer on the particle surface: if the ratio is too low, the hydrophobic layer will be incomplete and unable to effectively block moisture; if the ratio is too high, the hydrophobic layer may be too thick, affecting the dispersibility and optical properties of the particles.

[0011] The cesium tungsten bronze nanomaterial has a particle size of 5-50 nm. This particle size range is beneficial for fully utilizing the LSPR effect and small polaron absorption, while maintaining good dispersion of nanoparticles in the matrix and avoiding light scattering and increased haze caused by excessively large particle size.

[0012] Furthermore, the present invention provides a method for preparing the above-mentioned surface-modified cesium tungsten bronze nanomaterials, comprising the following steps:

[0013] (1) Grinding and dispersion: Cesium tungsten bronze powder with an initial particle size of 20-1000 nm, zirconium oxide grinding media and solvent are added to a grinding device for grinding; the grinding media is zirconium oxide beads with a particle size of 0.05-0.5 mm, the mass ratio of grinding media to cesium tungsten bronze powder is (5-50):1; the grinding time is 10-60 min, the grinding frequency is 65-83 Hz, and the solid content of the grinding system is 10 wt%-50 wt%.

[0014] (2) In-situ surface modification: During the grinding process, a coupling agent with hydrophobic functional groups is added to the grinding system, so that the coupling agent undergoes in-situ hydrolysis-condensation reaction on the surface of cesium tungsten bronze particles to form a hydrophobic layer.

[0015] (3) Fine grinding and dispersion: Add dispersant and continue grinding to the target particle size to obtain surface-modified cesium tungsten bronze nanomaterials.

[0016] In step (1), the initial particle size of the cesium tungsten bronze powder is preferably 20-500 nm. The solvent is one of water and ethanol, isopropanol, ethyl acetate, toluene, or a mixture of water and solvent; the amount of water in the solvent is 1-10 times the amount of coupling agent. The presence of water is a necessary condition for the hydrolytic coupling agent to react, but the amount of water must be strictly controlled: too little water will result in incomplete hydrolysis, while too much water may lead to particle agglomeration or affect the performance of the cesium tungsten bronze.

[0017] The grinding equipment can be a planetary ball mill, a stirred mill, a sand mill, or other wet grinding equipment.

[0018] In step (2), the coupling agent is added during the grinding process. The mechanical force generated during grinding and the newly formed active sites on the particle surface promote the chemical bonding between the coupling agent and the particle surface. The coupling agent with hydrophobic functional groups can be a silane coupling agent, a titanate coupling agent, or an aluminate coupling agent, etc. The grinding time after adding the coupling agent is 5-20 min. During this time, the coupling agent completes hydrolysis and undergoes a condensation reaction with the hydroxyl groups on the particle surface, forming stable Si-OW (or Ti-OW, Al-OW) covalent bonds. The hydrophobic layer is firmly attached to the particle surface through chemical bonding, rather than simple physical adsorption, thus exhibiting excellent durability.

[0019] In step (3), the dispersant is selected from one or more of polyamide dispersants, acrylate dispersants, polyurethane dispersants, and polyethylene glycol-600, and the amount used is 5%-80% of the mass of cesium tungsten bronze powder. The addition of the dispersant can further improve the dispersion stability of nanoparticles in solvent and prevent particle agglomeration and sedimentation. The grinding time after adding the dispersant is 5-40 min, and the particles are further ground to achieve the target particle size (5-50 nm), while ensuring that the dispersant is loaded on the particle surface.

[0020] Furthermore, the present invention provides a transparent heat-insulating film comprising the above-mentioned surface-modified cesium tungsten bronze nanomaterial; the film has a visible light transmittance of ≥70% at 550 nm, a blocking rate of ≥95% in the near-infrared region of 780-2500 nm, and a near-infrared blocking performance degradation of less than 5% after aging at 85 ℃ / 85%RH for 60 days.

[0021] The transparent heat-insulating film can be prepared by dispersing surface-modified cesium tungsten bronze nanomaterials in an organic resin matrix (such as acrylic resin, polyurethane resin, polyvinyl butyral, etc.) and then performing processes such as coating, curing, and hot pressing. Due to the dual modification of the nanomaterial surface with a hydrophobic layer and a dispersant, it exhibits excellent compatibility and dispersion stability in the organic resin, resulting in a film with high transparency and long-lasting thermal barrier properties.

[0022] The present invention has the following beneficial effects:

[0023] 1. Excellent Service Stability: This invention constructs a hydrophobic layer on the surface of cesium tungsten bronze nanoparticles, effectively blocking the contact between water molecules and oxygen and the particle surface, thus improving the material's resistance to damp heat. After aging for 60 days under harsh conditions of 85 ℃ and 85%RH, the near-infrared blocking performance of the obtained material decreased by less than 5%, far superior to the unmodified cesium tungsten bronze material (decreased by 12.8%). Under irradiation by a 250 W high-pressure mercury lamp, with the UV lamp at a distance of 25 cm from the sample, after aging for 600 min, the thermal insulation performance of the cesium tungsten bronze nanoparticles decreased by less than 0.5%, superior to the near-infrared attenuation of the unmodified sample (1%).

[0024] 2. This invention proposes mechanochemical in-situ alkylation: silane hydrolysis and condensation are simultaneously completed during nano-grinding and dispersion formation, allowing a silicon-oxygen network to preferentially form and adhere to the particle surface, thus achieving "dispersion stabilization + interface passivation" in a one-step process. Simultaneously, by introducing silanes with different functional groups, a correlation is established between molecular structure, grafting / film formation, hydrophobicity, and service stability, achieving nano-sizing and surface modification in a one-step process: This invention combines wet grinding with in-situ hydrolysis-condensation reaction of coupling agents, simultaneously completing particle size refinement and surface hydrophobic layer construction in a single process, avoiding the problems of process complexity and low efficiency caused by the step-by-step nano-sizing and surface modification in traditional methods. This provides a basis for the design of products with subsequent industrial application value.

[0025] 3. Excellent transparent heat insulation performance: The obtained transparent heat insulation film has a visible light transmittance of ≥70% at 550 nm and a blocking rate of ≥95% in the near-infrared region of 780-2500 nm. It has both high transparency and strong heat blocking ability, meeting the application requirements of building energy-saving window film and automotive film.

[0026] 4. Simple process and scalable production: The preparation method of this invention is based on a mature wet grinding process, with low equipment investment, simple operation and high production efficiency, making it suitable for large-scale industrial production. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 The image shows the XRD pattern of the KH550-modified cesium tungsten bronze in Embodiment 1 of the present invention.

[0029] Figure 2 This is a SEM image of the KH550-modified cesium tungsten bronze in Embodiment 1 of the present invention.

[0030] Figure 3 The thermal analysis curves are those of the cesium tungsten bronze sample without surface modification in Example 1 of this invention.

[0031] Figure 4 The thermal analysis curve of the KH550-modified cesium tungsten bronze in Example 1 of this invention is shown.

[0032] Figure 5 The infrared spectrum of the KH550-modified cesium tungsten bronze in Example 1 of this invention is shown.

[0033] Figure 6The contact angle of the cesium tungsten bronze coating modified with KH550 silane coupling agent in Example 1 of this invention.

[0034] Figure 7 This is the transmittance spectrum of the composite film of KH550 modified cesium tungsten bronze and PVB in Example 1 of the present invention after 60 days of damp heat aging (85 ℃, 85%RH).

[0035] Figure 8 The image shows the XRD pattern of the unmodified cesium tungsten bronze in Comparative Example 1 of this invention.

[0036] Figure 9 This is a SEM image of the unmodified cesium tungsten bronze sample in Comparative Example 1 of this invention.

[0037] Figure 10 The transmittance spectrum of the unmodified cesium tungsten bronze and PVB composite film in Comparative Example 1 of this invention after 60 days of damp heat aging (85 °C, 85%RH).

[0038] Figure 11 The images are high-resolution electron microscope (HRTEM) images of the unmodified and KH550 in-situ modified cesium tungsten bronze samples in Comparative Example 1 and Example 1 of the present invention. (a) Unmodified cesium tungsten bronze, (b) KH550 modified cesium tungsten bronze.

[0039] Figure 12 The thermogravimetric curve of cesium tungsten bronze modified with dimethyldiethoxysilane coupling agent in Example 2 of this invention.

[0040] Figure 13 This is the energy dispersive X-ray spectral elemental distribution diagram of the cesium tungsten bronze modified with dimethyldiethoxysilane in Example 2 of the present invention.

[0041] Figure 14 This is the transmittance spectrum of the composite film of dimethyldiethoxysilane modified cesium tungsten bronze and PVB in Example 2 of the present invention after 60 days of damp heat aging (85 °C, 85%RH).

[0042] Figure 15 This invention relates to CsO modified with dimethyldiethoxysilane under different aging times (0-9 days, 85℃ / 85% RH) in Comparative Example 2 of the present invention. 32 Transmittance spectra of WO3 / PVB composite films. Among them, (a) is the film prepared by directly mixing CWO dispersion with silane coupling agent and then with PVB; (b) is the film prepared by one-step mechanical grinding of silane coupling agent modified cesium tungsten bronze and PVB.

[0043] Figure 16 This is the energy dispersive X-ray spectral distribution of the elemental surface of the titanate-modified cesium tungsten bronze in Example 3 of the present invention.

[0044] Figure 17 This is the transmittance spectrum of the titanate-modified cesium tungsten bronze film in Example 3 of the present invention after 31 days of aging in a "double 85" aging chamber.

[0045] Figure 18 The transmittance curve of the titanate-modified cesium tungsten bronze film in Example 3 of the present invention after irradiation with ultraviolet light for 600 min is shown.

[0046] Figure 19 This is the energy dispersive X-ray spectral distribution of the cesium tungsten bronze modified with aluminate in Example 4 of the present invention.

[0047] Figure 20 This is the transmittance spectrum of the aluminate-modified cesium tungsten bronze film in Example 4 of the present invention after 31 days of aging in a "double 85" aging chamber.

[0048] Figure 21 The transmittance curve of the aluminate-modified cesium tungsten bronze film in Example 4 of this invention after irradiation with ultraviolet light for 600 min is shown.

[0049] Figure 22 The transmittance curve of the composite film of cesium tungsten bronze and PVB prepared in Comparative Example 1 in Example 4 after being irradiated with ultraviolet light for 600 min.

[0050] Figure 23 This refers to the contact angle of the cesium tungsten bronze coating modified with n-octyltriethoxysilane in Example 5 of the present invention. Detailed Implementation

[0051] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0052] Unless otherwise specified, the experimental methods used in the following experimental examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0053] Example 1

[0054] This embodiment describes a surface-modified cesium tungsten bronze nanomaterial, its preparation method, and its application. The steps are as follows:

[0055] Weigh 40 g of ethyl acetate and Cs 0.32 4.0 g of WO3 powder was placed in a beaker, ultrasonically dispersed for 10 min, and then transferred to a nano-milling machine. The powder was then processed according to Cs... 0.325% by weight of WO3 powder was added with γ-aminopropyltriethoxysilane (KH550) coupling agent, and the molar ratio of water to coupling agent was 3:1. Zirconia beads (0.1 mm in diameter, 200 g) were used as the grinding medium, and the mixture was ground for 10 min at a set frequency of 80 Hz to obtain a silane coupling agent-modified cesium tungsten bronze nano-dispersion. The resulting slurry was washed with ethanol, dried, and the resulting powder was used for testing. As a control, an unmodified cesium tungsten bronze dispersion (CWO) without silane coupling agent was prepared under the same conditions.

[0056] Figure 1 The XRD pattern of KH550-modified cesium tungsten bronze shows that the crystal phase is pure cesium tungsten bronze (PDF#83-1334), indicating that the addition of silane coupling agent does not change the crystal structure of CWO. Figure 1 The XRD refinement results of KH550-modified cesium tungsten bronze have the corresponding lattice parameters a = b = 7.41314 Å, c = 7.58377 Å.

[0057] Figure 2 The image shows the microstructure of cesium tungsten bronze nanoparticles modified with silane coupling agent. It can be seen that the cesium tungsten bronze modified with KH550 coupling agent maintains a relatively uniform particle size distribution (50-200 nm).

[0058] Figure 3 The thermal analysis curves are for the unmodified cesium tungsten bronze sample.

[0059] Figure 4 The thermal analysis curves for KH550-modified cesium tungsten bronze are shown. To quantitatively assess the degree of modification on the cesium tungsten bronze surface, the amount of silane coupling agent grafted onto a unit mass of CWO support was calculated. The grafting rate was calculated using the following formula:

[0060] (1)

[0061] GY represents the grafting rate (mol / g), ΔW% represents the mass loss rate (%) of the modified sample relative to the unmodified CWO within the characteristic decomposition temperature range, and M represents the molar mass (g / mol) of the product after hydrolysis of the silane coupling agent. Since the modification amount is relatively small, m can be considered... 样品 With m CWO The same applies, so the grafting rate on the cesium tungsten bronze surface can be calculated from formula (1) as 0.027 mol / g.

[0062] In addition, it can be seen from the infrared spectrum that ( Figure 5 Unmodified CWO sample at 3423 cm -1 and 1625 cm -1The presence of distinct hydroxyl stretching and bending vibration peaks at 1096 cm⁻¹ confirms that the CWO surface is rich in hydroxyl functional groups. The sample modified with KH550 silane coupling agent retained the characteristic peaks of CWO while exhibiting distinct peaks at 1096 cm⁻¹. -1 886 cm -1 and 793 cm -1 The presence of characteristic absorption peaks for Si-O-Si bonds at 2969 cm⁻¹ indicates the successful formation of a silica network structure. The silane coupling agent-modified sample showed an absorption peak at 2969 cm⁻¹. -1 and 2926 cm -1 The absorption peaks appearing at 2851 cm⁻¹ correspond to the asymmetric stretching vibrations of -CH₃ and -CH₂, respectively. -1 The peak at 1385 cm⁻¹ belongs to the symmetric stretching vibration of -CH₂, while the peak at 1385 cm⁻¹ belongs to the symmetric stretching vibration of -CH₂. -1 The absorption peak at the point originates from the bending vibration peak of -CH3. The appearance of these characteristic peaks indicates the presence of hydrophobic alkyl segments in the sample, suggesting that the silane coupling agent has been successfully modified onto the CWO surface through chemical bonding.

[0063] Figure 6 Contact angle test results of cesium tungsten bronze coatings modified with KH550 silane coupling agent. The coatings were prepared by dipping a cesium tungsten bronze ethyl acetate dispersion onto a glass slide. Unmodified CWO exhibited hydrophilic properties with a contact angle of 26.8°. After modification with KH550 silane coupling agent, the contact angle significantly increased to 72.7°, indicating the successful introduction of hydrophobic functional groups into the CWO surface. This result is consistent with the characteristic absorption peaks of -CH3 and -CH2 observed in FTIR characterization. Figure 1 These results demonstrate that surface wettability of CWO materials can be effectively controlled by modification with KH550 silane coupling agent.

[0064] To construct a highly stable nano-dispersion system, 3.17 g of dispersant BYK2001 was added after grinding silane coupling agent and CWO for 10 min, and grinding continued for 8 min to finally obtain a stable cesium tungsten bronze nano-dispersion. 15.00 g of PVB ethanol solution (solid content 15 wt%) was weighed, and 0.68 g of triethylene glycol diisooctanoate and a certain amount of the above CWO nano-dispersion (diluted 5 times with ethyl acetate, and 0.7 g of the diluted solution) were added. After thorough mixing, the mixture was injected into a mold (2.5 cm × 2.5 cm × 0.38 mm) to form a film, which was then hot-pressed to obtain a transparent heat-insulating composite film. The film was placed in a constant temperature and humidity test chamber (HS-100, Nanjing Wuhe) and aged for 60 days at 85 ℃ and 85%RH according to GB / T 2423.50-1999. During the aging process, samples were periodically taken to test the UV-Vis-NIR transmittance spectrum. To quantify and facilitate comparison of changes in the optical properties of cesium-tungsten-bronze composite films, the visible light transmittance at the maximum absorption wavelength of 550 nm is used as the standard for evaluating the film's transparency. Alternatively, the visible light transmittance T can also be used. Vis The near-infrared light transmittance T is used to evaluate the transparency of the film (%) (wavelength range of 380-780 nm). NIR The thermal insulation performance of the film was evaluated by (%) (wavelength range of 780-2500 nm). The two parameters were calculated using formulas (2) and (3), while the change in near-infrared light transmittance (ΔT) after accelerated aging of the film was also evaluated. NIR Visible light transmittance and near-infrared light transmittance are used as parameters for evaluating film stability. These are calculated using the following formulas:

[0065] T Vis = 100% (2)

[0066] T NIR = 100% (3)

[0067] Where T(λ) represents the transmittance at wavelength λ. The corresponding near-infrared shielding efficiency is defined as:

[0068] S NIR =100%-T NIR (4)

[0069] Similarly, the average transmittance T in the ultraviolet region (250-380 nm) UV With shielding rate S UVDefined in the same way (integration interval replaced with 250-380 nm). The KH550-modified cesium tungsten bronze and PVB composite film sample has a visible light transmittance of 71.6% at 550 nm wavelength and a near-infrared transmittance of 6.1%, corresponding to a near-infrared shielding capability of 93.9%. After aging the film in a "double 85" test chamber for 60 days, the change in transmittance of the film sample in the near-infrared region (ΔT) is... NIR ) is 3.4% ( Figure 7 ).

[0070] Comparative Example 1

[0071] This comparative example provides a method for preparing cesium tungsten bronze powder, the steps of which are as follows:

[0072] Weigh 40 g of ethyl acetate and Cs 0.32 4.0 g of WO3 powder was placed in a beaker and ultrasonically dispersed for 10 min. The dispersion was then transferred to a nanomilling machine, where 200 g of zirconia beads (0.1 mm in diameter) were used as the grinding medium. The mixture was ground for 10 min at a set frequency of 80 Hz to obtain a silane coupling agent-modified cesium tungsten bronze nanodispersion. The resulting slurry was washed with ethanol, dried, and the resulting powder was used for testing.

[0073] Figure 8 The image shows the XRD pattern of unmodified cesium tungsten bronze, the sample being a pure cesium tungsten bronze phase (PDF#83-1334). XRD refinement of the cesium tungsten bronze sample was performed... Figure 1 and Figure 8 The XRD refinement results show that there are slight changes in the lattice parameters. The KH550 modified cesium tungsten bronze has a larger a and a smaller c (a = b = 7.41314 Å, c = 7.58377 Å) compared with the unmodified cesium tungsten bronze (a = b = 7.40815 Å, c = 7.59597 Å), indicating that there are fewer oxygen vacancies in KH550 (J AmCeram Soc, 2019(102): 5386-5400), which is beneficial to improving the stability of cesium tungsten bronze under humid and hot conditions (InorgChem, 2024(63): 2486-2494). Figure 9The SEM image of the unmodified cesium tungsten bronze sample shows that its particle size distribution is between 50-200 nm. To construct a highly stable nano-dispersion system, 3.17 g of dispersant BYK2001 was added to the slurry after grinding for 10 min, and grinding was continued for 8 min to finally obtain a stable cesium tungsten bronze nano-dispersion. 15.00 g of PVB ethanol solution (solid content 15 wt%) was weighed, and 0.68 g of triethylene glycol diisooctanoate and a certain amount of the above CWO nano-dispersion (0.7 g of the diluted solution after diluting the dispersion slurry 5 times) were added. The mixture was then hot-pressed into a heat-insulating composite film. The film was placed in a "double 85" aging chamber (85 ℃, 85%RH) for 60 days. The visible light transmittance of the CWO / PVB composite film sample at a wavelength of 550 nm was 70.0%, and its transmittance in the near-infrared region was 6.2%, corresponding to a near-infrared shielding capability of 93.8%. After aging the film in a "double 85" test chamber for 60 days, the change in light transmittance of the film sample in the near-infrared region (ΔT) is recorded. NIR ) is 12.8% ( Figure 10 As can be seen from Example 1 and Comparative Example 1, in-situ surface modification of cesium tungsten bronze with KH550 can effectively improve the hygrothermal stability of cesium tungsten bronze. To further reveal the state of the silane coupling agent on the surface of cesium tungsten bronze, high-resolution electron microscopy (HRTEM) was used to characterize the microstructure of the samples. Figure 11 The results showed that the cesium tungsten bronze samples with KH550 surface modification had an amorphous layer with a thickness of approximately 3-5 nm on the surface. Figure 11 b, marked with a green dashed line), while Cs is not modified. 0.32 This feature was not observed in WO3. Figure 11 a). Using Fourier transform analysis with Digital Micrograph software, the lattice spacing of the unmodified CWO was determined to be approximately 0.32 nm, corresponding to the (200) crystal plane of cesium tungsten bronze. The silane-modified sample showed a reduction in interplanar spacing to 0.31 nm, a result consistent with the trend of reduced cell volume and decreasing spacing of crystal plane parameters a and b obtained through XRD refinement.

[0074] Example 2

[0075] This embodiment describes a surface-modified cesium tungsten bronze nanomaterial, its preparation method, and its application. The steps are as follows:

[0076] Weigh 40 g of ethyl acetate and Cs 0.32 4.0 g of WO3 powder was placed in a beaker, ultrasonically dispersed for 10 min, and then transferred to a nano-milling machine. The powder was then processed according to Cs... 0.32Dimethyldiethoxysilane coupling agent was added at 5% by weight of WO3 powder, with a water-to-coupling agent molar ratio of 2:1. Zirconia beads (0.1 mm in diameter, 200 g) were used as the grinding medium, and the mixture was ground for 10 min at a set frequency of 73.2 Hz to obtain a silane coupling agent-modified cesium tungsten bronze nano-dispersion. Then, 2.0 g of dispersant BYK2001 was added, and grinding continued for 8 min to finally obtain a stable cesium tungsten bronze nano-dispersion.

[0077] Figure 12 Thermogravimetric analysis (TGA) curves of cesium tungsten bronze modified with dimethyldiethoxysilane coupling agent are shown. Calculations indicate that the grafting rate on the cesium tungsten bronze surface is 0.039 mol / g.

[0078] Figure 13 The energy dispersive X-ray spectroscopy elemental distribution diagram of CWO nanoparticles modified with dimethyldiethoxysilane shows that Si is uniformly distributed on the surface of CWO nanoparticles, confirming that the silane coupling agent achieves uniform modification of the CWO nanoparticle surface.

[0079] Weigh 15.00 g of PVB ethanol solution (solid content 15 wt%), add 0.68 g of triethylene glycol diisooctanoate and a certain amount of the above CWO nano-dispersion (dilute the dispersion slurry 5 times and take 0.7 g of the diluted solution), and heat press to form a heat-insulating composite film.

[0080] The film was placed in a "double 85" aging chamber (85 ℃, 85%RH) for 60 days of continuous aging. The CWO / PVB composite film sample had a visible light transmittance of 68.0% at a wavelength of 550 nm, and a near-infrared transmittance of 5.4%, corresponding to a near-infrared shielding capability of 94.6%. The change in near-infrared transmittance of the film sample in the near-infrared region (ΔT) after aging in the "double 85" chamber for 60 days was also measured. NIR ) is 2.0% ( Figure 14 ).

[0081] Comparative Example 2

[0082] This comparative example provides a method for preparing cesium tungsten bronze powder, the steps of which are as follows:

[0083] Weigh 40 g of ethyl acetate and Cs 0.32 4.0 g of WO3 powder was placed in a beaker and ultrasonically dispersed for 10 min. Then, it was transferred to a nanomilling machine, and 2.0 g of dispersant BYK2001 was added. Using zirconia beads (0.1 mm in diameter, 200 g) as the grinding medium, the mixture was ground for 18 min at a set frequency of 73.2 Hz to obtain a silane coupling agent-modified cesium tungsten bronze nanodispersion. Cs... 0.32WO3 dispersion was mixed with dimethyldiethoxysilane, and a certain amount of water was added (the molar ratio of water to silane coupling agent was 2:1). Then, it was blended with PVB to prepare a composite film. The film was subsequently aged for 9 days in an aging chamber (85 ℃, 85% relative humidity), and its aging performance was compared with that of a dimethyldiethoxysilane-modified CWO / PVB composite film prepared by in-situ mechanochemical-assisted milling. Figure 15 As shown. Experimental results indicate that, despite using the same silane coupling agent, its relationship with Cs... 0.32 The different binding modes of WO3 significantly affect Cs 0.32 The damp heat stability of WO3 / PVB composite films. After 9 days of aging, silane-modified Cs prepared by the direct mixing method... 0.32 The near-infrared light transmittance of the WO3 / PVB film changed by 6%. Figure 15 a), and silane-modified Cs prepared by mechanochemical-assisted grinding method 0.32 The near-infrared light transmittance of WO3 / PVB film changed by only 1.3% ( Figure 15 b). These results indicate that mechanochemical-assisted in-situ silanization can more effectively graft silane coupling agents onto Cs. 0.32 The WO3 surface gives it better moisture and heat resistance.

[0084] Example 3

[0085] This embodiment describes a surface-modified cesium tungsten bronze nanomaterial, its preparation method, and its application. The steps are as follows:

[0086] Weigh out 39.60 g of ethyl acetate and Cs 0.32 3.96 g of WO3 powder was ultrasonically dispersed for 10 min and then transferred to a nano-milling machine. (According to Cs...) 0.32 5% by weight of WO3 powder was added to isopropyl tristearate titanate (chemical formula: C 17 H 35 Cesium tungsten bronze (Ct)3Ti-O-CH(CH3)2 was obtained by grinding with zirconia beads (0.1 mm in diameter, 400.0 g) at a set frequency of 72.3 Hz for 10 min using a zirconium oxide beads as the grinding medium to obtain a cesium tungsten bronze dispersion modified with a titanate coupling agent. To obtain a more stable nano-dispersion system, 3.17 g of dispersant BYK2001 was added to the dispersion, and grinding was continued for 8 min to obtain a stable cesium tungsten bronze nano-dispersion. The dispersion was washed with ethanol, dried, and the resulting powder was analyzed using energy-dispersive X-ray spectroscopy (EDS), as shown in the figure. Figure 16 As shown, titanium atoms are uniformly distributed on the particle surface, confirming that the titanate coupling agent achieves uniform modification of CWO.

[0087] Weigh 15.00 g of PVB ethanol solution (solid content 15 wt%), add 0.68 g of triethylene glycol diisooctanoate and cesium tungsten bronze nano-dispersion modified with titanate coupling agent (after dilution 5 times, take 0.7 g of the diluted solution), mix thoroughly and then hot press to form a film to obtain a composite film of titanate modified cesium tungsten bronze and PVB.

[0088] The transmittance curve of the thin film shows that ( Figure 17 When cesium tungsten bronze is surface-modified with titanate, the composite film maintains approximately 60% visible light flux (380-780 nm) while exhibiting 5.5% near-infrared light flux (780-2500 nm), corresponding to a near-infrared light blocking rate of 94.5%. The transmittance spectrum of the titanate-modified cesium tungsten bronze film after 31 days of damp heat aging in a "double 85" aging chamber is shown below. Figure 17 With prolonged aging time, the transmittance in both the visible and near-infrared regions of the spectrum increased to varying degrees, with a 2.0% increase in near-infrared transmittance and a 6.0% change in visible transmittance. To investigate the UV resistance of the prepared cesium tungsten bronze film, a 250 W high-pressure mercury lamp was used. The distance between the sample and the lamp was 25 cm. After 600 min of UV irradiation, the change in transmittance of the film in the visible-near-infrared region was observed, and the results are as follows. Figure 18 As shown, the CWO / PVB composite films modified with titanate have similar UV resistance. After 600 min of UV irradiation, the transmittance in the visible light region changes by 0.1%, and the transmittance in the near-infrared region changes by 0.1%, demonstrating excellent UV resistance.

[0089] Example 4

[0090] This embodiment describes a surface-modified cesium tungsten bronze nanomaterial, its preparation method, and its application. The steps are as follows:

[0091] Weigh out 39.60 g of ethyl acetate and Cs 0.32 3.96 g of WO3 powder was ultrasonically dispersed for 10 min and then transferred to a nano-milling machine. (According to Cs...) 0.32 Add 5% by weight of WO3 powder isopropyl distearate aluminoacrylate (chemical formula (C... 17 H 35Cesium tungsten bronze (Ct)₂Al-O-CH(CH₃)₂ was ground with zirconia beads (0.1 mm in diameter, 400.0 g) as the grinding medium at a set frequency of 72.3 Hz for 10 min to obtain an aluminate coupling agent-modified cesium tungsten bronze dispersion. To obtain a more stable nano-dispersion system, 3.17 g of dispersant BYK2001 was added to the dispersion, and grinding was continued for 8 min to obtain a stable cesium tungsten bronze nano-dispersion. The dispersion was washed with ethanol, dried, and the resulting powder was plotted using energy-dispersive X-ray spectroscopy (EDS), as shown below. Figure 19 As shown, aluminum atoms are uniformly distributed on the particle surface, confirming that the aluminate coupling agent achieves uniform modification of CWO.

[0092] Weigh 15.00 g of PVB ethanol solution (solid content 15 wt%), add 0.68 g of triethylene glycol diisooctanoate and 0.7 g of aluminate-modified cesium tungsten bronze nano-dispersion (diluted 5 times, take the diluted solution), mix thoroughly and then heat press to obtain a composite film of aluminate-modified cesium tungsten bronze and PVB.

[0093] The transmittance curve of the thin film shows that ( Figure 20 When cesium tungsten bronze is modified with aluminate, the composite film maintains a visible light flux of about 60% (380-780 nm) and a near-infrared light flux of 9.5% (780-2500 nm), corresponding to a near-infrared light blocking rate of 90.5%.

[0094] The transmittance spectrum of aluminate-modified cesium tungsten bronze films after 31 days of damp heat aging in a "double 85" aging chamber is shown. Figure 20 With prolonged aging time, the transmittance in both the visible and near-infrared regions of the spectrum increased to varying degrees. The transmittance in the near-infrared region increased by 4.6%, while the transmittance in the visible region changed by 8.0%. To investigate the UV resistance of the prepared cesium tungsten bronze film, a 250 W high-pressure mercury lamp was used. The distance between the sample and the lamp was 25 cm. After 600 min of UV irradiation, the change in transmittance of the film in the visible-near-infrared region was observed. The results are as follows. Figure 21 As shown, the CWO / PVB composite films modified with aluminate exhibit similar UV resistance. After 600 min of UV irradiation, the transmittance in the visible light region changed by 0.1%, and the transmittance in the near-infrared region changed by 0.2%, demonstrating excellent UV resistance.

[0095] The CWO / PVB composite film prepared in Comparative Example 1 was subjected to UV light resistance testing. Using a 250 W high-pressure mercury lamp, with a distance of 25 cm between the sample and the lamp, the film was irradiated with UV light for 600 min. The change in transmittance of the CWO / PVB composite film in the visible-near-infrared region was then examined. The results are as follows: Figure 22 As shown, the transmittance of the unmodified CWO / PVB composite film in the visible light region increased to 2.0%, while the transmittance in the near-infrared region changed by 1.1%. It is evident that the composite film prepared from the cesium tungsten bronze nanomaterials of this application, compared to the composite film prepared in prior art document 1, exhibits a 95.0% reduction in transmittance change rate in the visible light region (from 2.0% to 0.1%) and an 81.8% reduction in transmittance change rate in the near-infrared region (from 1.1% to 0.2%), demonstrating better service stability.

[0096] Example 5

[0097] This embodiment describes a surface-modified cesium tungsten bronze nanomaterial, its preparation method, and its application. The steps are as follows:

[0098] Weigh 100 g of ethyl acetate and Cs 0.32 40.0 g of WO3 powder was placed in a beaker, ultrasonically dispersed for 10 min, and then transferred to a nano-milling machine. The powder was then processed according to Cs... 0.32 5% of the WO3 powder was added as an octyltriethoxysilane coupling agent, with a water-to-coupling agent molar ratio of 3:1. Zirconia beads (0.05 mm in diameter, 500 g) were used as the grinding medium, and the mixture was ground for 5 min at a set frequency of 65 Hz to obtain a silane coupling agent-modified cesium tungsten bronze nano-dispersion. Then, 2.0 g of dispersant BYK2001 was added, and grinding continued for 20 min to finally obtain a stable cesium tungsten bronze nano-dispersion.

[0099] Figure 23 The contact angle of the modified cesium tungsten bronze on the glass slide is shown. 15.00 g of PVB ethanol solution (solid content 15 wt%) was weighed, and 0.68 g of triethylene glycol diisooctanoate and a certain amount of the above CWO nano-dispersion (the dispersion slurry was diluted 20 times, and 1.2 g of the diluted solution was taken) were added. The mixture was then hot-pressed into a heat-insulating composite film. The film was placed in a "double 85" aging chamber (85 ℃, 85%RH) for 60 days. The visible light transmittance of the CWO / PVB composite film sample at 550 nm wavelength was 68.2%, and its transmittance in the near-infrared region was 10.1%, corresponding to a near-infrared shielding capability of 89.9%. After aging in the "double 85" chamber for 60 days, the change in transmittance of the film sample in the near-infrared region (ΔT) was measured. NIR The figure is 4.5%.

[0100] Example 6

[0101] This embodiment describes a surface-modified cesium tungsten bronze nanomaterial, its preparation method, and its application. The steps are as follows:

[0102] Weigh 100 g of ethyl acetate and Cs 0.32 10.0 g of WO3 powder was placed in a beaker, ultrasonically dispersed for 10 min, and then transferred to a nano-milling machine. The powder was then processed according to Cs... 0.32 Dodecyltriethoxysilane coupling agent was added at 2% by weight of WO3 powder, with a water-to-coupling agent molar ratio of 3:1. Zirconia beads (0.5 mm diameter, 500 g) were used as the grinding medium, and the mixture was ground for 20 min at a set frequency of 83 Hz to obtain a silane coupling agent-modified cesium tungsten bronze nano-dispersion. Then, 8.0 g of dispersant BYK2001 and 0.05 mm diameter zirconium beads were added, and grinding continued for 5 min to finally obtain a stable cesium tungsten bronze nano-dispersion. 15.00 g of PVB ethanol solution (15 wt% solids content) was weighed, and 0.68 g of triethylene glycol diisooctanoate and a certain amount of the above CWO nano-dispersion (the dispersion slurry was diluted 5 times, and 0.7 g of the diluted solution was taken) were added. The mixture was then hot-pressed into a thermal insulation composite film.

[0103] The CWO / PVB composite film sample has a visible light transmittance of 69.4% at a wavelength of 550 nm and a transmittance of 7.5% in the near-infrared region, corresponding to a near-infrared shielding capability of 92.5%.

[0104] Example 7

[0105] This embodiment describes a surface-modified cesium tungsten bronze nanomaterial, its preparation method, and its application. The steps are as follows:

[0106] Weigh 40 g of ethyl acetate and Cs 0.32 12.0 g of WO3 powder was placed in a beaker, ultrasonically dispersed for 10 min, and then transferred to a nano-milling machine. The powder was then processed according to Cs... 0.32Two percent (by weight) of WO3 powder was added as a tridecafluorooctyltrimethoxysilane coupling agent, with a water-to-coupling agent molar ratio of 3:1. Zirconia beads (0.2 mm in diameter, 60 g) were used as the grinding medium, and the mixture was ground for 10 min at a set frequency of 83 Hz to obtain a silane coupling agent-modified cesium tungsten bronze nano-dispersion. Then, 0.6 g of dispersant BYK2001 and 0.05 mm diameter zirconium beads were added, and the mixture was ground for another 40 min at a set frequency of 65 Hz to finally obtain a stable cesium tungsten bronze nano-dispersion. 15.00 g of PVB ethanol solution (15 wt% solids content) was weighed, and 0.68 g of triethylene glycol diisooctanoate and a certain amount of the above CWO nano-dispersion (the dispersion slurry was diluted 15 times, and approximately 0.8 g of the diluted solution was taken) were added. The mixture was then hot-pressed into a thermal insulation composite film.

[0107] The CWO / PVB composite film sample has a visible light transmittance of 69.4% at a wavelength of 550 nm and a transmittance of 7.5% in the near-infrared region, corresponding to a near-infrared shielding capability of 92.5%.

[0108] Example 8

[0109] This embodiment describes a surface-modified cesium tungsten bronze nanomaterial, its preparation method, and its application. The steps are as follows:

[0110] Weigh 100 g of ethyl acetate and Cs 0.32 30.0 g of WO3 powder was placed in a beaker, ultrasonically dispersed for 10 min, and then transferred to a nano-milling machine. The powder was then processed according to Cs... 0.32 50% of the WO3 powder was added as a methyltriethoxysilane coupling agent, with a water-to-coupling agent molar ratio of 3:1. Zirconia beads (0.2 mm diameter, 207 g) were used as the grinding medium, and the mixture was ground for 20 min at a set frequency of 83 Hz to obtain a silane coupling agent-modified cesium tungsten bronze nano-dispersion. Then, 12.0 g of dispersant BYK2001 and 0.1 mm diameter zirconium beads were added, and the mixture was ground for another 40 min at a set frequency of 65 Hz to finally obtain a stable cesium tungsten bronze nano-dispersion. 15.00 g of PVB ethanol solution (15 wt% solids content) was weighed, and 0.68 g of triethylene glycol diisooctanoate and a certain amount of the above CWO nano-dispersion (the dispersion slurry was diluted 15 times, and approximately 0.8 g of the diluted solution was taken) were added. The mixture was then hot-pressed into a thermal insulation composite film.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A surface-modified cesium tungsten bronze nanomaterial, characterized in that: It includes cesium tungsten bronze nanoparticles and a hydrophobic layer loaded on the surface of the cesium tungsten bronze nanoparticles. The particle size of the cesium tungsten bronze material is 5-50 nm.

2. The surface-modified cesium tungsten bronze nanomaterial according to claim 1, characterized in that: The hydrophobic layer is formed by an in-situ hydrolysis-condensation reaction of a coupling agent with hydrophobic functional groups.

3. The method for preparing the surface-modified cesium tungsten bronze nanomaterial according to claim 1 or 2, characterized in that, The steps are as follows: (1) Cesium tungsten bronze powder and solvent are ground in a grinding medium to obtain a grinding system; (2) Add a coupling agent to the grinding system to carry out hydrolysis-condensation reaction, then add a dispersant and continue grinding to the target particle size to obtain surface-modified cesium tungsten bronze nanomaterials.

4. The method for preparing surface-modified cesium tungsten bronze nanomaterials according to claim 3, characterized in that: In step (1), the mass ratio of cesium tungsten bronze powder to grinding media is 1:5-50; the grinding time is 10-60 min; the grinding frequency is 65-83 Hz; and the solid content in the grinding system is 10 wt%-40 wt%.

5. The method for preparing surface-modified cesium tungsten bronze nanomaterials according to claim 4, characterized in that: The grinding media are zirconium oxide beads with a particle size of 0.05-0.5 mm; the cesium tungsten bronze powder has a particle size of 20-1000 nm.

6. The method for preparing surface-modified cesium tungsten bronze nanomaterials according to claim 3, characterized in that: In step (2), the coupling agent is selected from one or more of dimethyldimethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, n-octyltriethoxysilane, dodecyltriethoxysilane, tridecafluorooctyltrimethoxysilane, KH550, KH560, titanate coupling agent and aluminate coupling agent.

7. The method for preparing surface-modified cesium tungsten bronze nanomaterials according to claim 6, characterized in that: The molar ratio of Si, Ti, or Al elements in the coupling agent to W elements in the cesium tungsten bronze is 0.02-0.50:1; the amount of dispersant used is 5%-80% of the mass of the cesium tungsten bronze powder.

8. The method for preparing surface-modified cesium tungsten bronze nanomaterials according to claim 6, characterized in that: The hydrolysis-condensation reaction is carried out at a temperature of 5-25 °C for 5-20 min; the grinding time is continued for 5-40 min.

9. The method for preparing surface-modified cesium tungsten bronze nanomaterials according to any one of claims 4-8, characterized in that: The target particle size is 5-50 nm.

10. The application of the cesium tungsten bronze nanomaterial according to claim 1 or 2 in the preparation of energy-saving window film or automotive film.

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