Fabrication of Novel Superhydrophobic Surfaces and Water Droplet Bouncing Behavior - Part 1: Stable ZnO-PDMS Superhydrophobic Surface with Low Hysteresis Constructed Using ZnO Nanoparticles

A superhydrophobic surface has many advantages in micro/nanomechanical applications, such as low adhesion, low friction and high restitution coefficient, etc. In this paper, we introduce a novel and simple route to fabricate superhydrophobic surfaces using ZnO nanocrystals. First, tetrapod-like ZnO nanocrystals were prepared via a one-step, direct chemical vapor deposition (CVD) approach. The nanostructured ZnO material was characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD) and the surface functionalized by aminopropyltriethoxysilane (APS) was found to be hydrophobic. Then the superhydrophobic surface was constructed by depositing uniformly ZnO hydrophobic nanoparticles (HNPs) on the Poly(dimethylsiloxane) (PDMS) film substrate. Water wettability study revealed a contact angle of 155.4 +/- 2 degrees for the superhydrophobic surface while about 110 degrees for pure smooth PDMS films. The hysteresis was quite low, only 3.1 +/- 0.3 degrees. Microscopic observations showed that the surface was covered by micro- and nano-scale ZnO particles. Compared to other approaches, this method is rather convenient and can be used to obtain a large area superhydrophobic surface. The high contact angle and low hysteresis could be attributed to the micro/nano structures of ZnO material; besides, the superhydrophobic property of the as-constructed ZnO-PDMS surface could be maintained for at least 6 months. (C) Koninklijke Brill NV, Leiden, 2010

乳化剂和分散相含量对乳化液黏度的影响

采用旋转黏度计分别测量了当乳化剂和分散相的质量分数变化时,柴油-甲醇-水三相乳化液以及柴油-水二相乳化液的黏度.实验发现,乳化剂和分散相的质量分数均对乳化液黏度有影响:当乳化剂的质量分数小于4.8%时,柴油-甲醇-水三相乳化液的黏度均大于柴油-水二相乳化液的黏度;当乳化剂的质量分数大于4.8%时,若分散相质量分数小于20%,三相乳化液的黏度小于二相乳化液的黏度,若分散相质量分数大于20%,则三相乳化液的黏度大于二相乳化液的黏度,且随着分散相含量的增加,两者的黏度差也增大;就柴油-甲醇-水三相乳化液而言,即使分散相的质量分数相同,若甲醇和水的比例不同,其黏度也有差异;乳化剂含量对乳化液黏度的影响要小于分散相含量的影响

Preparation and characterization of microencapsulated hexadecane used for thermal energy storage

Polyurea microcapsules about 2.5 mum in diameter containing phase change material for thermal energy storage application were synthesized and characterized by interfacial polycondensation method with toluene-2,4-diisocyanate and ethylenediamine as monomers in an emulsion system. Hexadecane was used as a phase change material and OP, which is nonionic surfactant, and used as an emulsifier. The chemical structure and thermal behavior of the microcapsules were investigated by FTIR and thermal analysis respectively. The results show encapsulated hexadecane has a good potential as a solar energy storage material.

Microencapsulation of n-eicosane as energy storage material

For heat energy storage application, polyurea. microcapsules containing phase change material, n-eicosane, were synthesized by using interfacial polymerization method with toluene- 2,4-diisocyanate (TDI) and diethylenetriamine (DETA) as monomers in an emulsion system. Poly(ethylene glycol)octyl-phenyl ether (OP), a nonionic surfactant, was the emulsifier for the system. The experimental result indicates that TDI was reacted with DETA in a mass ratio of 3 to 1. FT-IR spectra confirm the formation of wall material, polyurea, from the two monomers, TDI and DETA. Encapsulation efficiency of n-eicosane is about 75%. Microcapsule of n-eicosane melts at a temperature close to that of n-eicosane, while its stored heat energy varies with core material n-eicosane when wall material fixed. Thermo-gravimetric analysis shows that core material n-eicosane, micro-n-eicosane and wall material polyurea can withstand temperatures up to 130, 170 and 250 degreesC, respectively.

Stability and demulsification of emulsions stabilized by asphaltenes or resins

Experimental data are presented to show the influence of asphaltenes and resins on the stability and demulsification of emulsions. It was found that emulsion stability was related to the concentrations of the asphaltene and resin in the crude oil, and the state of dispersion of the asphaltenes and resins (molecular vs colloidal) was critical to the strength or rigidity of interfacial films and hence to the stability of the emulsions. Based on this research, a possible emulsion minimization approach in refineries, which can be implemented utilizing microwave radiation, is also suggested. Comparing with conventional heating, microwave radiation can enhance the demulsification rate by an order of magnitude. The demulsification efficiency reaches 100% in a very short time under microwave radiation. (C) 2003 Elsevier Inc. All rights reserved.

A study of shear viscosity of interfacial films containing alkyl metal phosphates

Experimental data are presented to show the influence of alkyl metal phosphates, Shengli resin fraction, and NaCl, on the shear viscosity of interfacial films and the stability of emulsions. It was found that the alkyl metal phosphates and the Shengli resin fraction could enhance the shear viscosity of interfacial films and the stability of emulsions. NaCl (0.01-0.03 mol L-1) could change the shear viscosity of interfacial films containing alkyl metal phosphates and the Shengli resin fraction. The shear viscosity of interfacial films containing ethyl iron phosphate and the Shengli resin fraction decreased with the increase of the concentration of NaCl. On the other hand, NaCl could decrease the stability of the emulsions. (C) 2004 Elsevier B.V. All rights reserved.

Salt-assisted microwave demulsification

Experimental data are presented to show the influence of a very small amount of inorganic salt on the demulsification of water-in-oil emulsions. It was found that some inorganic salts could effectively enhance the demulsification efficiency and increase the light transmittance of the water separated from the emulsions. The demulsification efficiency may reach 100% in a very short time under microwave radiation.

Demulsification of emulsions exploited by enhanced oil recovery system

Experimental data are presented to show the influence of the enhanced oil recovery system's components, alkali, surfactant, and polymer, on the demulsification and light transmittance of the water separated from the emulsions. Among which, the effects of surfactants, polyoxyethylene (10) alkylphenol ether (OP-10) and sodium petroleum sulfonate (CY-1) on emulsion stability, are the strongest of any component, the effects of polymer, hydrolytic polyacrylamide (HPAM) 3530S, on emulsion stability are the weakest. This research also suggests a possible emulsion minimization approach, which could be implemented in refineries utilizing microwave radiation. Compared with conventional heating, microwave radiation can effectively enhance the demulsification rate by an order of magnitude and increase the light transmittance of the water separated from the emulsions. The demulsification efficiency may reach 100% in a very short. time under microwave radiation.

Activated carbon supported bimetallic CoMo carbides synthesized by carbothermal hydrogen reduction

A carbothermal hydrogen reduction method was employed for the preparation of activated carbon supported bimetallic carbide. The resultant samples were characterized by BET surface area measurement, X-ray diffraction, and temperature-programmed reduction-mass spectroscopy. The results showed that nanostructured beta-Mo2C can be formed on the activated carbon by carbothermal hydrogen reduction above 700 degreesC. The particle sizes of beta-Mo2C increase with increasing reaction temperatures and Mo loading. The bimetallic CoMo carbide can be synthesized by the carbothermal hydrogen reduction even around 600 degreesC. The bimetallic CoMo carbide is from carbothermal hydrogen reduction of CoMoO4 precursor and is easily formed when the Co/Mo molar ratio is 1.0. Separation of the bimetallic CoMo carbide phase into Mo carbide and Co metal occurs when the temperature of the reduction is above 700 degreesC. The addition of a second metal such as Co and Ni, decreases the formation temperature of carbide because the second metal promotes formation of CHx species from reactive carbon atoms or groups on carbon material and hydrogen, which further carburizes oxide precursors. (C) 2003 Elsevier Science Ltd. All rights reserved.

Layer-by-layer assembly of carbon nanotubes and Prussian blue nanoparticles: A potential tool for biosensing devices

A promising method for assembling carbon nanotubes (CNTs) and poly(diallyldimethylammonium chloride) protected Prussian blue nanoparticles (P-PB) to form three-dimensional (3D) nanostructured films is proposed. The electrostatic interaction, combined with layer-by-layer self-assembly (LBL), between negatively charged CNTs and positively charged P-PB is strong enough to drive the formation of the 3D nanostructured films. Thus, prepared multilayer films were characterized by ultraviolet-visible-near-infrared spectroscopy (UV-vis-NIR), scanning electron microscopy (SEM) and cyclic voltammetry (CV).

Fabrication, thermal stability and mechanical properties of novel (W0.5Al0.5)C-0.8-Co composite prepared by mechanical alloying and hot-pressing sintering

A novel cemented carbides (W0.5Al0.5)C-0.8-Co with different cobalt contents were prepared by mechanical alloying and hot-pressing technique. Hot-pressing technique as a common technique was performed to fabricate the bulk bodies of the hard alloys. The novel cemented carbides have superior mechanical properties compared to WC-Co. The density, operating cost of the novel material were much lower than WC-Co. There is almost no eta-phase in the (W0.5Al0.5)C-0.8-Co cemented carbides system although the carbon deficient get the value of 20%, and successfully got the nanostructured rounded (W0.5Al0.5)C-0.8 particles.

Hybrid permeable metal-base transistor with large common-emitter current gain and low operational voltage

We demonstrate the suitability of N,N'-diphenyl-N,N'-bis(1-naphthylphenyl)-1,1'-biphenyl-4,4'-diamine (NPB), an organic semiconductor widely used in organic light-emitting diodes (OLEDs), for high-gain, low operational voltage nanostructured vertical-architecture transistors, which operate as permeable-base transistors. By introducing vanadium oxide (V2O5) between the injecting metal and NPB layer at the transistor emitter, we reduced the emitter operational voltage.

Morphology control of nanoscale PbS particles in a polyol process

Nanostructured PbS with different morphologies and particle sizes have been prepared through a polyol process. Narrow size distribution for star-shaped, octahedral, tetradecanehedral, and cubic products were achieved by slowly introducing the source materials using a peristaltic pump in the presence of poly(vinylpyrrolidone) (PVP) as additive. Systematic variation of the kinetic factors, including the additive, the reaction temperature, the duration time, the ratio of source materials, the Sulfur sources, and the Pb(Ac)(2)center dot 3H(2)O concentration, reveals that the morphology depends mainly on the supersaturation degree of the free sulfur ions released from thiourea under elevated temperature.

Ethylene polymerization by (alpha-diimine)nickel(II) complexes bearing different substituents on para-position of imines activated with MMAO

A series of (alpha-diimine)nickel(II) complexes [ArN = C(Nap)C = NAr]NiBr2 (Nap = 1,8-naphthdiyl, Ar = 2,6-Me2C6H3, 3a; Ar = 2,4,6-Me3C6H2 3b; Ar = 2,6-Me-2-4-tBuC(6)H(2), 3c; Ar 2,6-Me-2-4-BrC6H2, 3d; Ar = 2,6-Me-2-4-ClC6H2, 3e; Ar 2,6-iPr(2)C(6)H(3), 3f; Ar = 2,4,6-iPr(3)C(6)H(2), 3g; Ar = 2,6-iPr-4-BrC6H2, 3h) have been synthesized, characterized, and investigated as precatalysts for ethylene polymerization in the presence of modified methylaluminoxane (MMAO).