Materials Literature
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A new soluble, low band-gap polymer, poly(2,3-dihexylthieno[3,4-b]pyrazine)2b, which is dark blue–black in the neutral state and which becomes transparent light yellow when doped has been prepared; it has a doped film conductivity of 3.6 × 10–2 S cm–1 and a band-gap (film) of ca. 0.95 eV making it one of the lowest ba…
A series of chiral esters has been prepared that exhibits unusual liquid-crystalline properties. In this family of materials the general molecular structure is one where a rigid aromatic core has two peripheral aliphatic chains attached to it, one of which carries a chiral carbon atom adjacent to the core itself. The…
The ability of room temperature vulcanizing (RTV) silicone rubber insulator coatings to suppress leakage current, thereby preventing power outages due to contamination, was studied. The RTV coatings were applied to porcelain suspension and line post insulators for a comparative study of the performance of coated and u…
Abstract High density polyethylene (HDPE) is toughened by particles of rigid inorganic filler CaCO 3 , which is treated with phosphate. The stress‐strain curve of the HDPE/modified‐CaCO 3 (80/20) composite covers a greater area than that of HDPE, and the impact strength of HDPE is greatly improved by modified CaCO 3 f…
A rotaxane with two rigidly held porphyrins as stoppers is synthesized by a copper(I)-based template strategy.
The validation of the thermal step method, which makes it possible to determine the electric field and the space charge distributions in insulating materials, is described. Validation was done by testing the numerical treatment, and then by depositing real corona charges in a well-localized zone of the sample. Other v…
We present an atomistic simulation of the structure of transition-metal glasses based on inter-atomic forces derived from quantum theory. Using the inter-atomic potentials calculated within the hybridized nearly-free-electron tight-binding-bond theory introduced in the preceding paper, we construct models for Ni-Y, Ni…
Polystyrene substrates were modified by radio-frequency plasma deposition from mixtures of various organic vapors (acetone, methane, methanol, and formic acid) and oxygen. The resulting surfaces exhibited a wide range of surface oxygen concentrations, as measured by electron spectroscopy for chemical analysis (ESCA).…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInterfacial segregation in two-phase polymer blends with diblock copolymer additives: the effect of homopolymer molecular weightKevin H. Dai, Edward J. Kramer, and Kenneth R. ShullCite this: Macromolecules 1992, 25, 1, 220–225Publication Date (Print):January 1, 1992Publicati…
Siloxane–oxide hybrid coatings have been prepared via the hydrolysis–condensation of diethoxydimethylsilane and various metallic alkoxides, M(OR)n with M = Si, Ti, Zr and Al. The rheological behaviour of the precursor sols and their hydrophobic character due to the presence of methyl groups, allows the formation of fi…
The authors present the principles and application examples of a recently refined, computerised, surface photovoltage (SPV) method. This new method is capable of wafer-scale, non-contact mapping of metal contaminants in the bulk and on the surface with sensitivities as high at 10 10 atoms cm -3 . They demonstrate the…
Perovskite‐type (La 1‐ x Sr x )MnO 3 (0 x 0.3) was synthesized through the sol–gel process at low temperature (400° to 500°C). Poly(acrylic acid) (PAA) was used to make a gel from an aqueous solution of lanthanum, strontium, and manganese nitrates. The particle‐diameter distribution of the manganites had a maximum val…
Fluorescence and fluorescence excitation spectra have been measured for solid solutions of tetrathiophene in tetradecane at 12 and 4.2 K. At 4.2 K, the spectra exhibit full vibrational resolution {inhomogeneous origin [full width at half-maximum, (FWHM)] approximately 5 cm−1 }. Narrow band excitation and detection est…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular recognition via base pairing: photoinduced electron transfer in hydrogen-bonded zinc porphyrin-benzoquinone conjugatesAnthony Harriman, Yuji Kubo, and Jonathan L. SesslerCite this: J. Am. Chem. Soc. 1992, 114, 1, 388–390Publication Date (Print):January 1, 1992Publi…
The \ensuremath{\alpha}-relaxation dynamics in a hard-sphere system is studied solving microscopic-mode-coupling equations. The solutions for coherent and incoherent dynamical structure factors, the transversal correlation functions, and the moduli are presented for all wave vectors. The wave-vector dependence of fitt…
There are a number of calculations in the literature of the effect of statistical surface roughness on the specular and diffuse scattering of neutrons and x rays which impinge on surfaces at grazing incidence. These calculations do not agree with one another and in some cases lack internal consistency. In this paper I…
We present the method and results of two phase-separation experiments performed on the binary-polymer blend polyisoprene-poly(ethylene-propylene). Elastic light scattering and optical microscopy were used to follow the phase separation after quenches into the coexistence region of the phase diagram. For off-critical q…
From the specific-heat (${\mathit{C}}_{\mathit{p}}$) measurements on the isostructural ${\mathrm{NH}}_{4}$L(${\mathrm{SO}}_{4}$${)}_{2}$\ensuremath{\cdot}${4\mathrm{H}}_{2}$O (L=La, Ce, Pr, Nd, Sm, Eu, Gd, and Tb) Tb) crystals at 100 K T300 K, it is shown that these crystals undergo two structural phase transitions, $…
Abstract Large single crystals of orthorhombic K 2 ZnCl 4 with optical quality have been grown by the Czochralski method. The elastic constants and their temperature and pressure derivatives have been determined from ultrasonic resonance frequencies of thick plates of different orientation and the shift of these frequ…
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