A series of hierarchically mesostructured silica nanoparticles (MSNs) less than 100 nm in size were fabricated by means of a one‐step synthesis using dodecanethiol (C12SH) and cetyltrimethylammonium ...bromide (CTAB) as the dual template, and trimethylbenzene (TMB) as the swelling agent. Silica nanoparticles with varied morphologies and structures, including mesoporous silica nanoparticles with tunable pore size, mesoporous silica nanoparticles with a thin solid shell, hollow mesoporous silica nanoparticles with tunable cavity size, and hollow mesoporous silica nanoparticles with a thin solid shell, were obtained by regulating the TMB/CTAB molar ratio and the stirring rate with the assistance of C12SH. Silica particulate coatings were successfully fabricated by using MSNs with varied morphologies and structures as building block through layer‐by‐layer dip‐coating on glass substrates. The thickness and roughness of the silica particulate coatings could be tailored by regulating the deposition cycles of nanoparticles. The silica particulate coatings composed of hollow mesoporous silica nanoparticles with a thin shell (S2) increased the maximum transmittance of slide glass from 90 to 96 %, whereas they reduced its minimum reflection from 8 to 2 % at the optimized wavelength region that could be adjusted from visible to near‐IR with a growing number of deposition cycles. The coatings also exhibited excellent superhydrophilic and antifogging properties. These mesostructured silica nanoparticles are also expected to serve as ideal scaffolds for biological, medical, and catalytic applications.
Tailor‐made nanospheres: A series of hierarchically mesostructured silica nanoparticles of less than 100 nm in size (see graphic) were facilely fabricated by means of a one‐step synthesis using dodecanethiol and cetyltrimethylammonium bromide as a dual template, and trimethylbenzene as the swelling agent.
Novel mesoporous silica nanoparticles of peculiar shapes were synthesized, from which hierarchically porous silica coatings were fabricated on glass substrates via layer-by-layer (LbL) assembly, ...followed by calcination. These porous silica coatings were highly transparent and superhydrophilic. The maximum transmittance reached as high as 94%, whereas that of the glass substrate is 91%. The time for a droplet to spread lower than 5° decreased to as short as 0.25 s. After the coating surface was treated with a low surface energy material, the surface became superhydrophobic (water contract angle >150°) with a very low sliding angle of <1°. Compared with MCM-41-type mesoporous silica nanoparticles, the coatings fabricated using the novel mesoporous silica nanoparticles possess much better self-cleaning property. We used scanning (SEM) and transmission (TEM) electron microscopy to observe the morphology and structure of nanoparticles and surfaces. Transmission spectra and their change with time were characterized by UV−vis spectrophotometer. We studied the surface wettability by a contact angle/interface system. The influence of mesopores on the transmittance and wetting properties of coatings was discussed on the basis of experimental observations.
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► Hydrophobic hollow silica nanoparticles (HSNs) were designed and synthesized. ► Hydrophobic HSNs were used to construct coatings by spray-coating. ► The coatings reached excellent ...superhydrophobicity after post-treatment at 150°C for 5h. ► The coatings were robust to both impact of water and acidic/basic droplets.
The present paper reports a novel, simple, and efficient approach to fabricate transparent superhydrophobic coatings on glass substrates by spray-coating stearic acid (STA) and 1H,1H,2H,2H-perflurooctyltriethoxysilane (POTS) co-modified hollow silica nanoparticles (SPHSNs), the surfaces of which were hydrophobic. The surface wettability of coatings was dependent on the conditions of post-treatment: the water contact angle of coating increased and then leveled off with increase in either the drying temperature or the drying time. When the coating was treated at 150°C for 5h, the water contact angle was as high as 160° and the sliding angle was lower than 1°, reaching excellent superhydrophobicity. They remained 159° and⩽1°, respectively, even after 3months storage under indoor conditions (20°C, 20%RH), demonstrating the long time stability of coating superhydrophobicity. The coating was robust both to the impact of water droplets (297cm/s) and to acidic (pH=1) and basic (pH=14) droplets. It showed good transparency in the visible-near infrared spectral range, and the maximum transmittance reached as high as 89%. Fourier transform infrared spectroscopy, transmission electron microscopy, differential scanning calorimetry, and thermogravimetric analysis were used to investigate the interactions among STA, POTS, and hollow silica nanoparticles (HSNs). Scanning electron microscopy and atomic force microscopy were used to observe and estimate the morphology and surface roughness of coatings. Optical properties were characterized by a UV–visible-near infrared spectrophotometer. Surface wettability was studied by a contact angle/interface system. The enhancement of hydrophobicity to superhydrophobicity by post-treatment was discussed based on the transition from the Wenzel state to the Cassie state.
This article describes a simple and convenient method to fabricate hierarchically structured coatings on glass substrates from soda lime glass by one-step hydrothermal method. The surfaces of the ...coatings are rough and are composed of flower-like particles assembled by nanoflakes or urchin-like particles constructed by nanowires. These rough surfaces exhibit superhydrophilicity, their water contact angles reaching 0° in less than 40 ms. After surface modification by 1H,1H,2H,2H-perfluorooctyltriethoxysilane, the wetting properties of these coatings switch from superhydrophilicity to superhydrophobicity, with water contact angles as high as 160° and slide angle as low as 1°. The formation mechanism of the hierarchically structured coatings is discussed in detail on the basis of experimental results.
Raspberry-like silica nanospheres were prepared by electrostatic self-assembly of polyelectrolytes and monodisperse silica nanoparticles of two different sizes, and their coatings were fabricated via ...layer-by-layer assembly with polyelectrolytes and following calcination. The morphology of the raspberry-like silica nanospheres and their coatings were observed by scanning and transmission electron microscopies. The surface properties of these coatings were investigated by measuring their water contact angles, and the results showed that such hierarchically structured coatings had unique superhydrophilic and antifogging properties. Finally, the formation mechanism and the property–structure relationship were discussed in details.
Raspberry-like silica nanospheres and their coatings were prepared via a facile layer-by-layer dip-coating approach, and the obtained hierarchically structured coatings demonstrated unique superhydrophilic and antifogging properties.
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•A facile dip-coating method was used to fabricate coatings.•The coatings showed excellent antireflection in the wavelength range of 400–2000nm.•The coatings were superhydrophobic ...after hydrophobic modification.
This paper reports a new design to fabricate broadband antireflective superhydrophobic coatings by versatile dip-coating of three silica-based sols: silica sol (below 10nm) prepared under acidic conditions (sol A), silica nanoparticle (ca. 25nm) suspension prepared by the Stöber method (sol B) and mesoporous silica nanoparticle (MSN) suspension, followed by chemical vapor deposition of 1H,1H,2H,2H-perfluorooctyltriethoxysilane. The maximum transmittance of coatings reached as high as 95.3% at the wavelength of 630nm, whereas the water contact angle was 153° with sliding angle ⩽5° by applying of the A2/B/MSN2 coating. The superhydrophobic A/B/MSN2 coating (water contact angle: 153°, sliding angle: ⩽5°) showed excellent antireflection in the wavelength range of 400–2000nm, especially in the wavelength range of 742–1573nm where the transmittance of glass substrate is significantly lower. Transmission electron microscopy was used to characterize the morphology of synthesized nanoparticles. Scanning electron microscopy and atomic force microscopy were used to observe the morphology and estimate the surface roughness of coatings. Optical properties were characterized by a UV–visible–near infrared spectrophotometer. Surface wettability was studied by a contact angle/interface system. The broadband antireflection of superhydrophobic A/B/MSN2 coating was discussed in detail.
A facile emulsifier-free emulsion polymerization approach was developed to fabricate highly monodisperse polystyrene (PS) spheres using potassium persulfate as the initiator and polyvinylpyrrolidone ...(PVP) as a stabilizer, respectively. It was found that the size of monodisperse PS spheres tends to decrease with increase of the PVP concentration, and the size of monodisperse PS spheres could be easily controlled in a wide range from 200 to 1500 nm simply by adjusting the concentration of PVP. The increase of monomer concentration led to the increase in size of monodisperse PS spheres. In contrast, the increase of initiator concentration resulted in the decrease in size of monodisperse PS spheres. These concentration changes, however, did not significantly affect the size distributions of PS spheres. It was also found that the size of monodisperse PS spheres obtained by adding the initiator at room temperature was larger than that by adding the initiator at 70°C, and the existence of inhibitor resulted in smaller PS spheres. The mechanisms in which the above factors influence the size and size distribution were discussed.
Mechanical, swelling, and optic properties of composite films prepared from soy protein isolate (SPI) and gelatin were investigated. With increasing gelatin ratio in composite films, tensile strength ...(TS), elongation to break (EB), elastic modulus (EM) and swelling property of the SPI/gelatin composite films increased. In addition, the films became more transparent, and easier to handle. When the ratio of SPI:gelatin was 4:6–2:8, the TS, EB, and other properties of composite film approached those of gelatin film and were better than those of SPI film. Particularly, the composite film was more economic than gelatin film, so it could be used as edible film instead of gelatin film for package. When the ratio of SPI:gelatin was 4:6, the influences of concentration of glycerin, pH value of SPI film-forming solution, thermal-treatment temperature of SPI film-forming solution and NaCl on mechanical and optic properties, and water content of composite films were also studied.
Hierarchically mesoporous silica nanoparticles (HMSNs) with uniform morphology and structure and with a diameter of ca. 100−220 nm were facilely fabricated using water, ethanol and ethyl ether as ...cosolvents. Template extraction and amino-functionalization were performed toward the HMSNs. These hierarchical mesopores are supposed to possess more advantages than conventional monomodal mesopores. Amino-functionalized HMSNs were homogeneously grafted with fluorescent molecules and loaded with Au nanoparticles (NPs), respectively. The extracted HMSNs were also successfully used to construct antireflection and superhydrophilc coatings. Drug release experiments showed that HMSNs exhibit much quicker rates of drug release compared with conventional mesoporous NPs due to their hierarchically mesoporous structures.
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