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Elastic aerogels have become a research hot spot in both academia and industry recently. The reported elastic aerogels are all made of hard materials by controlling their shapes. Herein we report an elastic aerogel made of a polymer elastomer with entropy elasticity. In the aerogel, cross-linked carboxyl nitrile rubber nanoparticles with hydrophilicity are dispersed in hydrophobic derivative of styrene-maleic anhydride alternating copolymer, forming a very special micro-nano surface structure with hydrophilic protrusions and hydrophobic depressions on the aerogel wall; therefore, the aerogel is not only superelastic but also superamphiphilic. A leak-free phase-change composite was prepared using the aerogel and paraffin, which can maintain at phase change temperature of paraffin for a longer time than the traditional one. The aerogel is also extremely suitable for desalination evaporators in solar-driven interfacial evaporation technology due to its superamphiphilicity, superelasticity, and ability to absorb sunlight. Exceptional evaporation rate of 2.78 kg·m-2·h-1 and evaporation efficiency of 170% could be reached even without using expensive light-absorbing materials. The evaporation rate exceeds that of most evaporators with expensive light-absorbing materials, and the evaporation efficiency exceeds the theoretical limit of conventional 2D solar evaporators. Both the phase-change composite and the evaporator can be easily recovered because the novel superelastic aerogel reported in this work is also recyclable.
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To overcome the two main obstacles of large-scale application of superspreading material, self assembly is used to prepare superspreading polymer membrane (SPPM) in this work. An amphiphilic SPPM is prepared by capillary force-driven self assembly using PP melt-blown nonwovens and polyvinyl alcohol (PVA). The prepared SPPM has low preparation cost and stable performance since self assembly needs low energy consumption, and the production is thermodynamically stable. By using cryo-electron microscopy, transmission electron microscopy, X-ray photoelectron spectrum and scanning electron microscope with energy dispersive X-ray spectroscopy. It is proved that PVA is successfully assembled on the fiber surface of PP melt-blown nonwovens. The prepared SPPM has excellent spreading performance, the "spreading times" of both water and oil are less than 0.5 s. They showed much superior performance compared to traditional materials when applied in oil-water separation, seawater desalination, and ion separation. This work will definitely promote the development of self assembly, superspreading materials, and related sciences.
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Fog harvesting is considered a promising freshwater collection strategy for overcoming water scarcity, because of its environmental friendliness and strong sustainability. Typically, fogging occurs briefly at night and in the early morning in most arid and semiarid regions. However, studies on water collection from short-term fog are scarce. Herein, we developed a patterned surface with highly hydrophilic interconnected microchannels on a superhydrophobic surface to improve droplet convergence driven by the Young-Laplace pressure difference. With a rationally designed surface structure, the optimized water collection rate from mild fog could reach up to 67.31 g m-2 h-1 (6.731 mg cm-2 h-1) in 6 h; this value was over 130% higher than that observed on the pristine surface. The patterned surface with interconnected microchannels significantly shortened the startup time, which was counted from the fog contact to the first droplet falling from the fog-harvesting surface. The patterned surface was also facilely prepared via a controllable strategy combining laser ablation and chemical vapor deposition. The results obtained in outdoor environments indicate that the rationally designed surface has the potential for short-term fog harvesting. This work can be considered as a meaningful attempt to address the practical issues encountered in fog-harvesting research.
Asunto(s)
Agua Dulce , Agua , Gases , Presión , Tiempo (Meteorología) , Interacciones Hidrofóbicas e HidrofílicasRESUMEN
The integral catalytic impeller can simultaneously improve reaction efficiency and avoid the problem of catalyst separation, which has great potential in applying heterogeneous catalysis. This paper introduced a strategy of combining electroless copper plating with 3D printing technology to construct a pluggable copper-based integral catalytic agitating impeller (Cu-ICAI) and applied it to the catalytic reduction of 4-nitrophenol (4-NP). The obtained Cu-ICAI exhibits very excellent catalytic activity. The 4-NP conversion rate reaches almost 100% within 90 s. Furthermore, the Cu-ICAI can be easily pulled out from the reactor to be repeatedly used more than 15 times with high performance. Energy-dispersive spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy characterizations show that the catalyst obtained by electroless copper plating is a ternary Cu-Cu2O-CuO composite catalyst, which is conducive to the electron transfer process. This low-cost, facile, and versatile strategy, combining electroless plating and 3D printing, may provide a new idea for the preparation of the integral impeller with other metal catalytic activities.
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The unmodified clay has been fully exfoliated in epoxy resin with the aid of a novel ultrafine full-vulcanized powdered rubber. Epoxy/rubber/clay nanocomposites with exfoliated morphology have been successfully prepared. The microstructures of the nanocomposites were characterized by means of X-ray diffraction and transmission electron microscopy. It was found that the unmodified clay was fully exfoliated and uniformly dispersed in the resulting nanocomposite. Characterizations of mechanical properties revealed that the impact strength of this special epoxy/rubber/clay nanocomposite increased up 107% over the neat epoxy resin. Thermal analyses showed that thermal stability of the nanocomposite was much better than that of epoxy nanocomposite based on organically modified clay.