Icephobic performance on the aluminum foil-based micro-/nanostructured surface

The research of superhydrophobic materials has attracted many researchers' attention due to its application value and prospects.In order to expand the serviceable range,people have investigated various superhydrophobic materials.The simple and easy preparation method has become the focus for superhydrophobic materials.In this paper,we present a program for preparing a rough surface on an aluminum foil,which possesses excellent hydrophobic properties after the treatment with low surface energy materials at high vacuum.The resulting contact angle is larger than 160° and the droplet cannot freeze on the surface above-10 ℃.Meanwhile,the modified aluminum foil with the thickness of less than 100 μm can be used as an ideal flexible applied material for superhydrophobicity/anti-icing.     

The fabrication of superhydrophobic copper films by a low-pressure-oxidation method

The lotus-leaf-like superhydrophobic copper was fabricated by a facile two-step method without the chemical modification, on which the water contact angle can reach 158° and the water-sliding angle is less than 10°. Reversible superhydrophobicity to superhydrophilicity transition was observed and controlled by alternation of UV irradiation and dark storage. More interestingly, the superhydrophobic surface exhibits superoleophilicity and all those properties can be well used in reversible switch, separating the water and oil and so on.     

Superhydrophobic poly(vinylidene fluoride) film fabricated by alkali treatment enhancing chemical bath deposition

Based on the lotus effect principle, the superhydrophobic poly(vinylidene fluoride) (PVDF) film was successfully prepared by the method of alkali treatment enhancing chemical bath deposition. The surface of PVDF film prepared in this work was constructed by many smooth and regular microreliefs. Oxygen-containing functional groups were introduced in PVDF film by treatment with aqueous NaOH solution. The nano-scale peaks on the top of the microreliefs were implemented by the reaction between dimethyldichlorosilane/methyltrichlorosilane solution and the oxygen-containing functional groups of PVDF film. The micro- and nano-scale structures, similar to the lotus leaf, was clearly observed on PVDF film surface by scanning electronic microscopy (SEM) and atomic force microscope (AFM). The water contact angle and sliding angle on the fabricated lotus-leaf-like PVDF film surface were 157° and 1°, respectively, exhibiting superhydrophobic property and self-cleaning property.     

Fabrication and surface characterization of biomimic superhydrophobic copper surface by solution-immersion and self-assembly

Biomimic superhydrophobic surfaces with contact angle greater than 150° and low sliding angle on copper substrate were fabricated by means of a facile solution immersion and surface self-assembly method. The scanning electron microscopy showed a nanoneedle structure copper surface with sporadic flower-like aggregates after treatment with sodium hydroxide and potassium persulfate solution. X-ray photoelectron spectroscopy and X-ray diffraction results confirmed that the formed nanoneedles were crystallized Cu(OH)₂. And the hydrophilic Cu(OH)₂ surface can be further modified into superhydrophobic through surface self-assembly with dodecanoic acid.     

Investigation of the catalysis and SERS properties of flower-like and hierarchical silver microcrystals

Noble metal nano/microstructures have attracted considerable attention because of their unique properties and their various applications. Controlling the shape of noble metal nano/microstructures is a promising strategy to tailor their physical and chemical properties for various applications in fields such as biological labeling and imaging, catalysis, and sensing. Among various specific structures, flower-like and hierarchical silver nano/microstructures have attracted increasing interest because exploration of these novel nano/microstructures with unusual optical properties can provide new perspectives into the rational design of novel materials. It is significantly more challenging to develop facile and effective solution approaches for systematic manipulation of the shape of Ag nano/microstructures. In this article, we revisited the ascorbic acid reduction method to prepare flower-like silver microcrystal with plate petals and hierarchical Ag microcrystal on a large scale and in high purity. Ascorbic acid plays two roles of a reducing agent and a crystal growth regulator. Therefore, the molar ratio of ascorbic acid and silver nitrate is critical to the formation of Ag microcrystal. The controlling of the two different Ag microstructures can be achieved by adjusting the molar ratio of the reactants in aqueous medium at room temperature. The as-prepared Ag microcrystals were characterized by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction. The flower-like Ag microcrystal with plate petals and hierarchical Ag microcrystal with nanoscale sharp tips and gaps could exhibit high catalytic activity and strong surface-enhanced Raman spectroscopy (SERS) activity due to the high surface area and the local electromagnetic field intensity enhancement, respectively. The potential application of the as-prepared Ag microcrystals in catalysis and SERS was investigated, which revealed that these two kinds of Ag microcrystals exhibit high catalytic activities to the NaBH₄-catalyzed reduction of 4-nitrophenol and significant SERS effect to 4-aminothiophenol molecular due to their nanoscale sharp tips and gaps. Therefore, the flower-like Ag microcrystal and hierarchical Ag microcrystal investigated here could be promising candidates for single particle catalyst and SERS.     

Wettability,optical property of a superhydrophobic YAG film

A flame-like superhydrophobic yttrium aluminum garnet surface was obtained by a simple approach under ambient conditions. The influences of the concentration of curing agent and paraffin wax in course of the experiment were investigated. The as-prepared film shows superhydrophobicity which has a water contact angle of 158 ± 1.0°, and sliding angle of 4 ± 1.0°. Moreover, the water contact angle of the rough surface remained higher than 150°, after exposure for 10 days. Transmission electronic microscope, scanning electronic microscope, fluorescence spectrometer and atomic force microscope were also used to characterize the samples.     

Superhydrophobic PEEK/PTFE composite coating

A simple and inexpensive method for forming a PEEK/PTFE superhydrophobic surfaces by controlling the topographical microstructures by adjusting the curing temperature has been proposed. The resulting porous surface, with ribbon-like randomly distributed double-scale structure and the lowest surface energy hydrophobic groups (-CF₃) has a water contact angle of 161°. PACS 06.60.Ei; 81.05.Rm; 81.20.Ev; 82.80.Pv     

Facile method to prepare lotus-leaf-like super-hydrophobic poly(vinyl chloride) film

A simple new approach was developed to obtain a super-hydrophobic PVC film from a natural lotus leaf using the nanocasting method. SEM shows that compared with a common smooth PVC film, a lotus-leaf-like surface structure was clearly observed on the super-hydrophobic PVC film. The water contact angle and rolling-off angle on the as-prepared lotus-leaf-like PVC film were 157 ± 1.8° and 3 ± 0.6°, respectively. The samples were kept at temperatures between 5 and 40 °C in the ambient atmosphere for 2 months, and no decrease in water contact angle was observed, nor was contamination observed.     

Experimental and simulation investigations of the peculiarities of relativistic electron beam scattering at a small angle of incidence on a thin flat target

The refraction angles θ _d of electron beams passing through aluminum and thin flat copper foils and reflection angles θ _r are measured. A microtron with 7.4 MeV particles is used as a source of electrons. The angle between the particle trajectory and the target surface α is varied in the range 5°–30°. The dependences of the refraction and reflection angles on the α angle and foil thickness δ are measured. A dosimetric film is used to make pictures of cross sections of the electron beam scattered by a thin 50 μm copper foil. Image processing allows the spatial distributions of refracted and reflected particles to be obtained. The processes of relativistic electron scattering at a small angle of incidence on a flat target are simulated by the Monte Carlo method. The results of simulation are compared with experimental data. Particle scattering at a bimetallic target consisting of 200-μm aluminum and 70-μm lead layers are simulated. A dependence of the spatial-energy distributions on the order of metal layers placed along electron trajectories is found.     

Fabrication of superhydrophobic film by microcellular plastic foaming method

To solve the complicated manufacturing operation and the usage of toxic solvent problems, a simple and novel method to fabricate superhydrophobic film by surface foaming method was introduced in this paper. The superhydrophobic property of the foamed material was obtained at a contact angle >150° and a rolling angle about 8°. The foamed material can instantly generate its superhydrophobicity via peeling process. The effects of blowing agent content, foaming time and peeling rate on the foam structure and superhydrophobicity were studied.     

The super hydrophobicity of ZnO nanorods fabricated by electrochemical deposition method

Electrochemical deposition method was employed to fabricate ZnO nanorods on zinc foil substrate in this paper. The structural observations of ZnO nanorods with different aspect ratios were carried out by field-emission scanning electron microscopy. The microstructures of ZnO nanorods were also characterized by X-ray diffraction and the changes in surface hydroxyls with electrochemical deposition time were analyzed by X-ray photoelectron spectroscopy. The study results show the aspect ratios of ZnO nanorods and the density of their surface hydroxyls are responsible for their superhydrophobicity. The fluorinated polymer coated ZnO nanorods showed an excellent superhydrophobic behavior with 167° contact angle of water droplet, which is larger than that of fluorinated polymer flat surface. The more the surface hydroxyls are, the more hydrophilic the surfaces are. Meanwhile, the larger the aspect ratio of ZnO nanorod arrays is, the larger its drophobicity is. The results of this study might pave a simple and feasibility pathway to the fabrication of superhydrophobic cleaning materials used in engineering fields.     

Superhydrophobic elastomer surfaces with nanostructured micronails

New approaches to the fabrication of microstructures of special shape were developed for polymers. Unusual superhydrophobic surface structures were achieved with the use of flexible polymers and hierarchical molds.Flexible polyurethane?acrylate coatings were patterned with microstructures with use of microstructured aluminum mold in a controlled UV-curing process. Electron microscope images of the UV-cured coatings on polymethylmethacrylate (PMMA) substrates revealed micropillars that were significantly higher than the corresponding depressions of the mold (even 47 vs. 35 μm). The elongation was achieved by detaching the mold from the flexible, partially cured acrylate surface and then further curing the separated microstructure. The modified acrylate surface is superhydrophobic with a water contact angle of 156° and sliding angle of < 10°.Acrylic thermoplastic elastomers (TPE) were patterned with micro?nanostructured aluminum oxide molds through injection molding. The hierarchical surface of the elastomer showed elongated micropillars (57 μm) with nail-head tops covered with nanograss. Comparison with a reference microstructure of the same material (35 μm) indicated that the nanopores of the micro?nanomold assisted the formation of the nail-shaped micropillars. The elasticity of the TPE materials evidently plays a role in the elongation because similar elongation has not been found in hierarchically structured thermoplastic surfaces. The hierarchical micronail structure supports a high water contact angle (164°), representing an increase of 88° relative to the smooth TPE surface. The sliding angle was close to zero degrees, indicating the Cassie–Baxter state.     

自清洁功能的超疏水微/纳米结构铜网用于高效的分离油水

本文介绍了一种简便的方法制备n-十二烷基三甲氧基硅烷@三氧化钨包覆的超亲油超疏水的铜网.所制备的铜网显示了较为突出的超亲油和超疏水性能,该铜网的水接触角大约有154.39°,而油接触角接近于0°.实验利用了各种有机溶剂和水的混合物对所制备网膜进行分离性能测试,结果表明所得涂覆铜网的油水分离效率高达99.3V,并且水的通量大约为9962.3 L·h~(-1)·m~(-2).所制备的铜网具有良好的稳定性,经过10次分离循环后分离效率仍然保持在90%以上.由于三氧化钨优异的光催化降解性能,所制备铜网具有自清洁能力.因此,被润滑油污染的网膜可以恢复超疏水性,而这种自清洁性使所制网膜可以反复用于油水分离.     

A novel and expeditious method to fabricate superhydrophobic metal carboxylate surface

This article has presented a novel method to fabricate superhydrophobic metal carboxylate surface on substrates like copper, ferrum, etc. This method markedly shortened the fabrication time to less than one second. The superhydrophobic effect is even better that the contact angle (CA) is 170±1° and the sliding angle (SA) <2°. Scanning electron microscopy (SEM) images showed micro-nano flower-like structures. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed that the flower-like structures are composed of Cu[CH₃(CH₂)₁₂COO]₂. The ethanol solution containing fatty acid and metal salt plays a key role in this method. This method has tremendous potentials in industrial production of superhydrophobic materials.     

Thickness measurement of cobalt foils using ultramicrotome cuts and electron microscopy

A method of thickness measurement of cobalt foils using transverse ultramicrotome cuts of foils embedded in Araldite is described. A new two-stage gelatine-carbon replica technique was developed. For a foil with inhornogeneous thickness, the method enables an exact determination of the position on the foil of the spot where thickness is measured. Although glass knives only were available for cutting, the accuracy of thickness measurement was better than ±1000 Å.     

Superhydrophobicity of polyvinylidene fluoride membrane fabricated by chemical vapor deposition from solution

Due to the chemical stability and flexibility, polyvinylidene fluoride (PVDF) membranes are widely used as the topcoat of architectural membrane structures, roof materials of vehicle, tent fabrics, and so on. Further modified PVDF membrane with superhydrophobic property may be even superior as the coating layer surface. The lotus flower is always considered to be a sacred plant, which can protect itself against water, dirt, and dust. The superhydrophobic surface of lotus leaf is rough, showing the micro- and nanometer scale morphology. In this work, the microreliefs of lotus leaf were mimicked using PVDF membrane and the nanometer scale peaks on the top of the microreliefs were obtained by the method of chemical vapor deposition from solution. The surface morphology of PVDF membrane was investigated by scanning electronic microscopy (SEM) and atomic force microscope (AFM). Elemental composition analysis by X-ray photoelectron spectroscopy (XPS) revealed that the material of the nanostructure of PVDF membrane was polymethylsiloxane. On the lotus-leaf-like PVDF membrane, the water contact angle and sliding angle were 155° and 4°, respectively, exhibiting superhydrophobic property.     

Excimer laser-assisted chemical process for formation of hydrophobic surface of Si (001)

Silicon (Si) wettability is one of the important parameters in the development of Si-based biosensing and lab-on-chip devices. We report on UV laser induced hydrophobicity of Si (001) wafers immersed in methanol during the irradiation with an ArF excimer laser. The irradiation with 800 pulses of the laser operating at 65 mJ/cm² allowed to significantly increase the hydrophobicity of investigated samples as characterized by the static contact angle change from 77° to 103°. Owing to the irradiation with relatively low laser fluence, no measurable change in surface morphology of the irradiated samples has been observed with atomic force microscopy measurements. The nature of the hydrophobic surface of investigated samples is consistent with X-ray photoelectron spectroscopy analysis that indicates formation of Si–O–CH₃ bonds on the surface of the laser-irradiated material.     

Behavior of charges locally injected into nanothin high-k SmScO3 dielectric

The behavior of charges locally injected from the probe of an atomic force microscope into nanothin films of high-k SmScO₃ dielectric deposited on a silicon substrate is studied by the method of Kelvin probe force microscopy. Prior to examination, the films were annealed at different temperatures. At temperatures above 900°C, the amorphous as-prepared films exhibit polycrystalline inclusions. In the films annealed at 900°C, the injected charge persists for a long time that several tens of times exceeds the charge retention time observed when conventional dielectrics, such as SiO₂ and Si₃N₄, are used. In addition, the diffusion of carriers in the plane of the dielectric layers sharply slows down.     

Facile fabrication of superhydrophobic polytetrafluoroethylene surface by cold pressing and sintering

A series of superhydrophobic polytetrafluoroethylene (PTFE) surfaces were prepared by a facile cold pressing and sintering method, and their microstructures and wetting behaviors could be artificially tailored by altering sintering temperature and using different masks. Specifically, the microstructures mainly depended on the sintering temperature, whereas the wetting behaviors, water contact angle (WCA) and sliding angle (SA), greatly hinged on both the sintering temperature and mask. Then a preferable superhydrophobic surface with WCA of 162 ± 2° and SA of 7° could be obtained when the sintering temperature was 360 °C and the 1000 grit abrasive paper was used as a mask. In addition, it was worth noting that the as-prepared surfaces exhibited excellent stability under UV illumination, which was the most key factor for them toward practical applications.     

Untersuchung der direkten Paarbildung durch Elektronen

The direct production of electron-positron-pairs by 31·5 MeV-electrons has been investigated using a counting device. The external electron beam of a betatron, collimated and by deflection cleaned of photons, passed through a thin copper foil, and was collected in a Faraday cup. The fast positrons emerging from the foil were analysed in a magnetic field and detected by a plastic scintillator. By varying the thickness of the foil the differential cross section for (real) trident production was obtained. It was found to amount to about one third of the cross section predicted byBhabha's theory (with k=k′=1).