Cellulose has received a tremendous amount of attention both in academia and industry owing to its unique structural features, impressive physical–chemical properties, and wide applications. This ...natural polymer is originally used for packaging, paper, lightweight composites, and so forth and is now being developed for various new areas, such as antibacterial treatment, catalysis, water purification and separation, and biological and environmental analysis. In the current article, we summarize the recent developments in the self-assembly of cellulose with various species including metal ions and metal and metal oxide nanoparticles. Then we highlight several key application areas of cellulose-based composites by reviewing the recent representative literature in each area. A significant part of this review demonstrates some exciting innovations for a wide range of practical applications of cellulose-based composites. Some challenges are also discussed with a view toward future developments.
We herein report a simple and effective method to fabricate excellent transparent superhydrophobic coatings. 3-Aminopropytriethoxysilane (APTS)-modified hollow silica nanoparticle sols were ...dip-coated on slide glasses, followed by thermal annealing and chemical vapor deposition with 1H,1H,2H,2H-perfluorooctyltrimethoxysilane (POTS). The largest water contact angle (WCA) of coating reached as high as 156° with a sliding angle (SA) of ≤2° and a maximum transmittance of 83.7%. The highest transmittance of coated slide glass reached as high as 92% with a WCA of 146° and an SA of ≤6°. A coating simultaneously showing both good transparency (90.2%) and superhydrophobicity (WCA: 150°, SA: 4°) was achieved through regulating the concentration of APTS and the withdrawing speed of dip-coating. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) were used to observe the morphology and structure of nanoparticles and coating surfaces. Optical properties were characterized by a UV–visible spectrophotometer. Surface wettability was studied by a contact angle/interface system. The effects of APTS concentration and the withdrawing speed of dip-coating were also discussed on the basis of experimental observations.
Silica–titania core–shell nanoparticles of 30, 40, 50, 55, 75, and 110 nm were prepared from tetraethyl orthosilicate (TEOS) and tetraisopropyl titanate (TIPT). After calcination, the amorphous ...titania shell transformed into anatase nanoparticles, and the silica–titania core–shell nanoparticles became raspberry-like nanoparticles. These nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and UV–vis spectroscopy. Hierarchically structured antireflective and self-cleaning particulate coatings were fabricated on glass substrates via layer-by-layer (LbL) assembly using silica–titania core–shell nanoparticles and silica nanoparticles as building blocks followed by calcination. The maximum transmittance of coated glass substrates reached as high as ca. 97%, while that of the glass substrates is only ca. 91%. The morphologies of the coatings were observed by SEM and atom force microscopy (AFM). Such hierarchically structured raspberry-like SiO2–TiO2 nanoparticle coatings had superhydrophilic and antifogging properties. The coatings also showed photocatalytic activity toward organic pollutants and thus a self-cleaning property.
Hierarchically porous graphene materials have great potential for applications in energy storage, electrocatalysis, water treatment, etc. Herein, a simple, superfast and effective approach was ...developed to hierarchically porous graphene with both micron-scale inter-layer pores and nanoscale in-plane holes, where a small amount of graphite acted as microwave absorbent to ignite a so-called reduction propagation process and the first reduced graphene oxide (rGO) acted as new igniter to reduce all the surrounding graphene oxide (GO). It was found that the porous structure and degree of reduction of hierarchically porous rGO could be tailored simply by controlling the microwave irradiation time and power. GO was completely reduced in 5 s of microwave irradiation. When the irradiation time was further extended, more crystalline graphitic domains formed on the rGO, and the number of in-plane holes, which were rare in more shortly irradiated specimens, increased significantly after more than 40 s microwave irradiation. The relationship between these physicochemical characteristics of the obtained hierarchically porous rGO and the microwave irradiation conditions is discussed in detail in this paper, which has great significance in designing hierarchically porous graphene materials required for supercapacitor electrodes, electrocatalysts, and water-treatment membranes.
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Inspired by the repair of DNA through efficient reformation of hydrogen bonds (H-bonds), herein we report a facile one-step approach to construction of self-healing antifogging thin films on the ...basis of partly cross-linked poly(vinyl alcohol)(PVA) and poly(acrylic acid)(PAA). By designing the molar ratio of hydroxyl groups to carboxyl groups, the cross-linked polymer thin films maintain abundant free hydroxyl groups to present excellent antifogging property, which is derived from the hydrophilicity and hygroscopicity of the thin films. The thin films showed smart intrinsic self-healing characteristics towards wounds caused by external forces, which is attributed to sufficient free hydroxyl groups at the scratched interfaces to reform H-bonds across the interfaces and a sufficient chain mobility that is indispensable for chain diffusion across the interfaces and hydroxyl groups association to form H-bonds. No synthetic surfaces reported so far possess all the unique characteristics of the polymer thin films: intrinsic self-healing, long-term antifogging, excellent mechanical property, high transmittance and large-scale feasibility.
Flower-like, boat-like, plate-like and ellipsoid-like CuO nanostructures were fabricated by simple modulation of reaction conditions. The as-prepared CuO nanostructures all show good catalytic ...activity by catalytic oxidation of MB.
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► Flower-like, boat-like, plate-like and ellipsoid-like CuO nanostructures were obtained by simple modulation of reactants and the time and temperature of hydrothermal treatment. ► The simple synthetic methods reported in this work allow large scale fabrication of CuO nanostructures with flexibility in morphological and dimensional control. ► The catalytic performance of as-prepared CuO products in the oxidation of MB was studied in presence of H
2O
2. All the obtained CuO nanostructures showed good catalytic activity in the degradation of aqueous MB.
In this work, flower-like, boat-like, plate-like and ellipsoid-like copper oxide (CuO) nanostructures were fabricated by simple modulation of reaction conditions. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, nitrogen adsorption–desorption measurements and UV–visible diffuse reflectance spectra were employed to characterize the obtained CuO nanostructures. Reactants, hydrothermal temperature and time were found to largely affect the morphology and structure of CuO nanostructures. Flower-like and boat-like CuO nanostructures were successively fabricated by increasing hydrothermal time. Plate-like and ellipsoid-like CuO nanostructures were produced by modulating the use of polyethylene glycol (PEG) and NH
3·H
2O. The formation mechanisms were proposed based on the experimental results, which show that both PEG and NH
3·H
2O play an important role in the formation of the morphology and structure of CuO. The catalytic activity of the as-prepared CuO nanostructures was demonstrated by catalytic oxidation of methylene blue (MB) in presence of hydrogen peroxide (H
2O
2). The as-prepared CuO nanostructures all show good catalytic activity.
Raspberry- and mulberry-like hierarchically structured silica particulate coatings were fabricated via facile in situ layer-by-layer assembly with monodisperse silica nanoparticles (NPs) of two ...different sizes followed by calcination. Raspberry-like and mulberry-like silica particulate coatings were achieved when the size ratio of two silica particles was 20/200 and 20/70 nm, respectively. The latter coating exhibited good antireflective property. Its maximum transmittance reached as high as 97%, whereas that of the glass substrate is only 91%. The morphologies of the coatings were observed by scanning electron microscopy and atom force microscopy. The surface properties of these coatings were investigated by measuring their water contact angles and the spreading time of water droplet. The results showed that such hierarchically structured coatings had superhydrophilic and antifogging properties.
In this study, we developed a simple and versatile strategy to fabricate hierarchically structured lotus-leaf-like superhydrophobic thin films. The thin films are broadband antireflective, and the ...average transmittance of coated glass substrates reached greater than 95% in the wavelength range of 530–1340 nm, in contrast to 92.0% for bare glass substrate. The thin film surface shows a static water contact angle of 162° and a sliding angle less than 4°. Moreover, the thin film is thermally stable up to 300 °C, and shows remarkable stability against strong acid, strong alkali, water drop impact, and sand impact abrasion, while retaining its superhydrophobicity. Further, the thin film can pass the 3H pencil hardness test. The current approach may open a new avenue to a variety of practical applications, including windshields, eyeglasses, windows of high rise buildings and solar cells, etc.
Silica nanospheres with varied morphologies and pore structures, including mesoporous nanospheres, nanospheres with hierarchical pores (from 2 to 100 nm), and hollow nanospheres of mesoporous shell, ...were fabricated at room temperature simply by regulating the ethanol/ethyl ether volume ratio in the starting solution. The silica nanostructures were characterized by small-angle X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption−desorption measurements. Based on experimental results, a plausible mechanism for the structural regulation of mesoporous silicas has been put forward. These novel nanostructures of hierarchical pores provide an ideal scaffold for biological, medical, and catalytic applications.
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