Materials Literature
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Films of several polyimides having various chain rigidities were prepared on silicon substrates from the poly(amic acid) precursors by a conventional spin-coat/dry/thermal imidization process: poly(p-phenylene pyromellitimide) (PMDA-PDA), poly(4,4′-oxydiphenylene pyromellitimide) (PMDA-ODA), poly(p-phenylene biphenylt…
To improve the hemocompatibility on hydrophobic biomedical materials by a simple coating technique, graft copolymers composed of a hydrophilic side chain with phospholipid polar groups and a hydrophobic backbone were synthesized. The hydrophilic chain had phospholipid polar groups, poly[2-methacryloyloxyethyl phosphor…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInvestigation of a Synthesis of meso-Porphyrins Employing High Concentration Conditions and an Electron Transport Chain for Aerobic OxidationJonathan S. Lindsey, Kristy A. MacCrum, John S. Tyhonas, and Yao Yuan ChuangCite this: J. Org. Chem. 1994, 59, 3, 579–587Publication D…
In this paper we study an organic system of geometrical spin frustration. m-N-methylpyridinium \ensuremath{\alpha}-nitronyl nitroxide (m-${\mathrm{MPYNN}}^{+}$) is a spin-1/2 organic radical. The simple salt, m-${\mathrm{MPYNN}}^{+}$\ensuremath{\cdot}${\mathrm{ClO}}_{4}^{\mathrm{\ensuremath{-}}}$\ensuremath{\cdot}1/3…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFerromagnetic nickel(II) polynuclear complexes with end-on azido as bridging ligand. The first nickel(II)-azido one-dimensional ferromagnetic systemsJoan Ribas, Montserrat Monfort, Carmen Diaz, Carles Bastos, and Xavier SolansCite this: Inorg. Chem. 1994, 33, 3, 484–489Publi…
A method is presented for the deposition of CdS thin films of 0.05–0.7 μm thickness from solutions at 50–70 °C containing citratocadmium(II) complex ions and thiourea. The films show an optical band gap Eg≳2.6 eV. Optical transmittance is about 80% for photon energy <Eg. The dark conductivity of the films is of…
The interactions between the phthalocyanine macrocycle Pc2- and the metal ions Co2+, Ni2+ and Cu2+ are analyzed\nin detail. It is concluded that u bonding is by far dominant, mostly due to strong charge donation from the pyrrolic\nnitrogen lone pairs into the empty or singly occupied (in Cu) 3d,, with additional effec…
Color tuning of luminescence via molecular engineering of the active polymer is important for the commercial application of π‐conjugated polymers in photonic devices. The synthesis of a series of regiospecific alkylated polythiophenes is described, in which the effective conjugation length could be varied by altering…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMatrix isolation FT-IR studies and ab initio calculations of hydrogen-bonded complexes of molecules modeling cytosine or isocytosine tautomers. 1. Pyridine and pyrimidine complexes with water in argon matrixesAlain Destexhe, Johan Smets, Ludwik Adamowicz, and Guido MaesCite…
The electronic structure, the linear optical properties, and the structural properties of α‐Al 2 O 3 in the corundum structure are studied by means of first‐principles local density calculations. An indirect band gap of 6.29 eV is obtained, which is almost the same as the direct band gap of 6.31 eV at Γ. The calculate…
Microwave discharges (2.45 GHz) have been generated in C60-containing Ar. The gas mixtures were produced by flowing Ar over fullerene-containing soot at a variety of temperatures. Optical spectroscopy shows that the spectrum is dominated by the d 3Πg–a 3Πu Swan bands of C2 and particularly the Δv=−2, −1, 0, +1, and +2…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew Series of Multifunctionalized Nickel(II)-Cyclam (Cyclam = 1,4,8,11-Tetraazacyclotetradecane) Complexes. Application to the Photoreduction of Carbon DioxideEiichi Kimura, Senji Wada, Mitsuhiko Shionoya, and Yohko OkazakiCite this: Inorg. Chem. 1994, 33, 4, 770–778Publicat…
ADVERTISEMENT RETURN TO ISSUEArticleNEXTPoly[(amino acid ester)phosphazenes]: Synthesis, Crystallinity, and Hydrolytic Sensitivity in Solution and the Solid StateHarry R. Allcock, Shawn R. Pucher, and Angelo G. ScopelianosCite this: Macromolecules 1994, 27, 5, 1071–1075Publication Date (Print):February 1, 1994Publicat…
We review our current understanding of the mechanical, electronic and structural properties of the element uranium, with the focus on the low-temperature regime in which the α-phase is stable. We start with a historical perspective, as the need for understanding the metallurgy of uranium so that its use as a nuclear f…
A model, based on a simple axisymmettical fiber/interphase/ matrix assembly, is derived to depict the oxidation behavior of ID‐SiC/C/SiC composites within the temperature range 900–1300°C and for 10 < P O2 < 100 kPa. It takes into account (i) the changes versus time of the geometry of the annular pore resulting…
The dependence of K Ic on the notch‐root radius has been examined for a notch radius as small as a few micrometers in a dense, fine‐grained, polycrystalline alumina ceramic. The notch radius can be systematically varied by using a semimanual procedure in a special jig which polishes out rather than cuts the specimen.…
Abstract Single‐crystal materials, along with other forms of condensed matter (ceramics, polymers, liquid crystals, etc.) are fundamental to modern technology. The basic research and production of new materials with “tailored” solid‐state physical properties therefore necessitate not only chemical synthesis but also t…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDiblock, ABC triblock, and random methacrylic polyampholytes: synthesis by group transfer polymerization and solution behaviorC. S. Patrickios, W. R. Hertler, N. L. Abbott, and T. A. HattonCite this: Macromolecules 1994, 27, 4, 930–937Publication Date (Print):February 1, 199…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis, spectroscopy, electrochemistry, spectroelectrochemistry, Langmuir-Blodgett film formation, and molecular orbital calculations of planar binuclear phthalocyaninesNagao Kobayashi, Herman Lam, W. Andrew Nevin, Pavel Janda, Clifford C. Leznoff, Toshiki Koyama, Atsushi…
First‐principles calculations based on density–functional theory and pseudopotentials are used to calculate the energies and relaxed structures of five low‐index surfaces of α‐alumina. Evidence for the reliability of the theoretical methods is provided by calculations of the lattice parameters and internal coordinates…