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The self-assembly properties and ER effects of the Polyaniline-Poly(ethylene glycol)-Polyaniline (PAn-PEG-PAn) triblock copolymers were studied in this paper. The results indicate that with the increase of solubility parameter of the solvent, PAn-PEG-PAn copolymers form into different morphologies of spheriods, vesicles and rods. PAn-PEG-PAn copolymers with vesicles morphology show the highest polarization strength, while those with rods have the most rapid polarization rate. Among the PAn-PEG-PAn copolymers of different morphologies, the PAn-PEG-PAn copolymer vesicles show the strongest ER effect. [ABSTRACT FROM AUTHOR]

Meso-scale metal phthalocyanine (MPc, M = Cu, Ni, Mn, or Co)-Fe[sub 3]O[sub 4] nanocomposites for EMR fluids have been prepared and well characterized. The results indicate that there exists chemical bonding between MPc and Fe[sub 3]O[sub 4] nanoparticles, and their strength of chemical bonding increases in the following order: NiPc < CuPc < CoPc ~ MnPc. Compared to Fe[sub 3]O[sub 4] nanoparticles, MPc-Fe[sub 3]O[sub 4] nanocomposites have superior ability to anti-oxidation and thermal stability; and show almost the same saturation magnetic strength, but much less coercive force. All MPc-Fe[sub 3]O[sub 4] nanocomposites have irregular spherical shape with D of 0.2∼0.4 µm. The EMR fluids containing MPc-Fe[sub 3]O[sub 4] nanocomposites in chlorinated paraffin Oil have excellent stability and redispersibilty. They show reversible significant field-induced shear stress, which increase linearly with the increment of electric field strength (E) or H and which are different for MPcFe[sub 3]O[sub 4] nanocomposites containing various metal elements, when E or H is applied respectively. Furthermore, field-induced shear stress shows obvious synergetic effect when E and H are applied simultaneously. [ABSTRACT FROM AUTHOR]

Ammonium metatungstate and cobalt nitrate were mixed at the molecular level in distilled water and then spray-decomposed to CoWO4/WO3 nanocomposite powder. The particle morphology, crystalline size, forming course, chemical composition and phase structure of the powder were studied by SEM, TEM, DTA-TG, IR and XRD, respectively. Results show that the powder is homogeneous, spherical and nano-aggregated. [ABSTRACT FROM AUTHOR]

Abstract: The flexural strength, pore size distribution, resistance to acid corrosion and thermal properties of sodium silicate/graphite composite bipolar plates for proton exchange membrane fuel cells (PEMFC) were investigated in this paper. The experiment results show that when the graphite content is greater than 40wt.%, the flexural strength of composite bipolar plate can attain 15MPa and this composite bipolar plate was not broken during machining the flow fields. The large amount of porosity in this composite bipolar plate is from the silica gel capillary pores because of the solidification of sodium silicate, which makes it possess a humidifying function during PEMFC operation. The corrosion current is about 10−4.5 Acm−2 from the polarization curves for this composite bipolar plate, which shows that this composite bipolar plate is acid-resistant. Na+ ions leached from this composite bipolar plate is only a small percentage of the total Na+ ion content in the composite bipolar plate after 1M H2SO4 solution corrosion at 30°C for 1h. Na+ ions in the acidic corrosion solution increased a little with temperature from 30 to 80°C. In addition, this composite bipolar plate was thermally stable from room temperature to 400°C. [Copyright &y& Elsevier]

Abstract: Positive-ion charged Pd nanoparticles were synthesized and anchored to –SO3 − clusters on Nafion™ membrane surface by means of selective force between –SO3 − clusters and charged particles, namely, electrostatic self-assembly of the membrane. The Pd loading of self-assembled membrane was about 1.73 μg/cm2. Methanol crossover of the Nafion™ membranes was suppressed after the assembled procedure. The methanol crossover current was reduced by as much as eight orders of magnitude compared to pure Nafion™ membrane while there was no reduction in the proton conductivity of the membrane. Methanol permeating across the resulting Nafion™ membranes was 1.3×10−15 mol cm−2 s−1, comparing with the value of pure Nafion™ membranes (self-assembled for 0 h) of 1.4×10−7 mol cm−2 s−1. The results demonstrate the promises of the application of such Pd-PDDA nanoparticle self-assembled Nafion™ membrane in DMFC. [Copyright &y& Elsevier]

The chemical state of oxygen on the surfaces of mixed electronic–ionic conducting La0.6Sr0.4Co1−yFeyO3 ceramics was characterized by X-ray photoelectron spectroscopy (XPS). It was ascertained that there are five different kinds of oxygen on the ceramic surfaces, including lattice oxygen (OL), chemisorbed oxygen (OC) in the forms of O2−, O−, and O2−, and oxygen in hydroxyl environment (OH). The concentration of OC+OH relative to total detected oxygen enhanced with the increase of Co/Fe ratio. In order to examine the relation between the chemical states of oxygen on the surfaces and the electrical nature of the ceramics, the mixed electronic–ionic conducting properties were investigated. At an identical measuring temperature, the electronic conductivity and ionic conductivity of La0.6Sr0.4Co1−yFeyO3 ceramics tended to rise with the increase of Co/Fe ratio. It was considered that the mixed electronic–ionic conducting properties are responsible for the complex chemical states of oxygen on the ceramic surfaces. [Copyright &y& Elsevier]

La0.6Sr0.4Co0.8Fe0.2O3 was synthesized by a citrate method, and the contributing factors to the formation of homogeneous fine powder with a pure perovskite-type structure were ascertained. The obtained La0.6Sr0.4Co0.8Fe0.2O3 exhibits superior sinterability and mixed electronic–ionic conduction properties than that synthesized by a traditional solid state reaction method. [Copyright &y& Elsevier]

A homogeneous, nanocomposite Ni/YSZ cermet powder was prepared by EDTA complexes–gel reduction process (CGRP). Zr–Y–Ni–O gel powder was formed from soluble complexes in aqueous solution. NiO/YSZ powder was obtained after the gel powder had been heat-treated in air for 2 h at 600 °C. Ni/YSZ powder was prepared by reducing the NiO/YSZ powder in hydrogen for 2 h at 850 °C. The X-ray diffraction (XRD) peak broadening result is consistent with the ZrO2 crystallite size of 38 nm in the Ni/YSZ cermet powder. The particle size of the Ni/YSZ cermet powder is 30–50 nm, according to the transmission electron microscopy (TEM) analysis. [Copyright &y& Elsevier]