Materials Literature
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Polyaniline is prepared by chemical polymerization of aniline in an acidic solution using H2O2 as an oxidant and ferrous chloride as a catalyst. A wide variety of synthesis parameters are studied, such as the amount of the catalyst, reaction temperature, reaction time, initial molar ratio of oxidant, monomer and catal…
The ordered [head-to-head (H−H) or tail-to-tail (T−T)] poly(amide−ester) was prepared by polycondensation of a symmetric monomer, isophthaloyl chloride (1), with 4-(2-aminoethyl)phenol (2) as a nonsymmetric monomer. The polymerization was conducted in NMP in the presence of triethylamine (TEA) at −20 °C by slow additi…
The magnetic properties of a series of Fe x Cd 1 - x PS 3 layered compounds ( x = 0.1−0.8) and of their methyl viologen intercalates have been studied. The results imply that the Fe 2+ ions are not randomly dispersed on the metallic sites, as they retain strong in-plane magnetic interactions even at high dilution. The…
Diblock copolymers in the melt exhibit order–disorder phase transitions (ODT), which are accompanied by strong concentration fluctuations. These transitions are generally described in terms of the random phase approximation (RPA) of Leibler and Fredrickson, which is able to explain small angle scattering results in th…
The phase behavior and linear viscoelasticity of a mixture of a matched diblock and triblock copolymer of styrene and ethylene−butene-1 are reported. The mixture undergoes reversible thermotropic transitions from a cylindrically ordered state at low temperatures to a spherically ordered state at intermediate temperatu…
We contrast the adsorption of human serum albumin (HSA) onto two solid substrates previously primed with the same polyelectrolyte of net opposite charge to form one of two alternative structures: randomly adsorbed polymer and the “brush” configuration. These structures were formed either by the adsorption of quaterniz…
The conformation of various polystyrene chains with first (G-1), second (G-2), and third generation (G-3) Fréchet-type dendrons at the repeat unit has been investigated with small-angle neutron scattering. The increased density of the attached dendrons leads to a systematically greater cross-sectional chain diameter D…
Characterizing the inherent flexibility of a protein provides an important link between structure and function. In this article, we examine some of the methods used to determine protein flexibility, and address several unanswered questions relating to them. We perform 4 ns simulations of bovine pancreatic trypsin inhi…
Deuterium nuclear magnetic resonance (NMR) powder spectra and spin-lattice relaxation times (T(1)) are used to measure the deuterium quadrupolar coupling constants (QCCs) chi(BD) and chi(ND) and to investigate the molecular reorientation of the BD(3) and ND(3) groups in solid deuterated borane monoammoniate, BD(3)NH(3…
The reactions of sodium sulfide or disulfide with sulfur, when heated, are examined through Raman spectroscopy. It is shown that whatever the composition of the mixtures, the solid sodium sulfide or disulfide transforms into the crystalline alpha-Na(2)S(4) phase in a first step, with alpha- or beta-Na(2)S(2) as an int…
We have identified a channel of bicontinuous microemulsion in three chemically distinct hompolymer/hompolymer/block copolymer (A/B/A−B) ternary bends. Experiments were conducted along the isopleth, defined by equal volumes of homopolymer and varying amounts of block copolymer, as a function of temperature. A symmetric…
The crystal structure and a phase transition of gadolinium orthoborate, GdBO 3, were studied by electron diffraction and X-ray powder diffraction. GdBO 3 crystallizes in the vaterite structure (LT), in a rhombohedral space group R 32 with the lattice constants of a = 6.6357(2) Å and c = 26.706(1) Å. The structure of t…
We describe the synthesis and characterization of alkyl-capped nanocrystalline Si (R̂- n −Si) prepared by the reaction of SiCl 4 with Mg 2 Si in ethylene glycol dimethyl ether (glyme) and surface-terminated with various alkyl groups, R̂- n −Si (R = methyl, ethyl, n -butyl, and n -octyl). This reaction produces crystal…
Hydrous ruthenium oxide (RuO 2 · x H 2 O or RuO x H y ) is a mixed electron−proton conductor with a specific capacitance as high as 720 F/g/proton, making it a candidate material for energy storage. The correlation between the structure and properties of RuO 2 · x H 2 O materials is not well understood due to their am…
A simple method to control the dosing of small adsorbate molecules onto solid surfaces from liquid solution is applied to quantitative surface-enhanced Raman scattering measurements on dielectric-overcoated silver-island films. The deposition method, based on substrate withdrawal from solution, is evaluated by measuri…
Nematic and left-handed chiral−nematic liquid crystals comprising methoxybiphenylbenzoate and ( S )−(−)-1-phenylethylamine pendants to a cyclohexane core were synthesized and characterized. Although pristine samples were found to be polycrystalline, thermal quenching following heating to and annealing at elevated temp…
Two layered tin(II) oxalate structures have been prepared by hydrothermal methods in the presence of structure-directing organic amines. The crystal data for these structures are as follows: oxalate I, [(CH 3 ) 2 NH(CH 2 ) 2 NH(CH 3 ) 2 ] 2+ [Sn 2 (C 2 O 4 ) 3 ] 2 - ·H 2 O, monoclinic, space group C 2/ c (no. 15), a =…
The tridentate trianion of N,N-bis(2-hydroxy-di-3,5-tert-butylphenyl)amine, H(3)L(3), forms 1:1 and 2:1 complexes with di-, tri-, or tetravalent transition metal ions where it can exist in four oxidation levels (C(28)H(40)NO(2))(3)(-)(,2)(-)(,1)(-)(,0), which are herein designated as L(3), L(2), L(1), and L(0), respec…
Optical reflectivity spectra were measured on cleaved surfaces of La1-xSrxMnO3 single crystals (x=0.175, T_C=283 K) over a temperature range 10-295 K. The optical conductivity $sigma(ω)$ shows, keeping single-component nature, incoherent-to-coherent crossover with increase of electrical conductivity. The $σ(ω)$ spectr…
Based on a symmetry argument, we study ground states of what we call MMX-chain compounds, which are the new class of halogen-bridged metal complexes. Commensurate density-wave solutions of a relevant multi-band Peierls-Hubbard model are systematically revealed within the Hartree-Fock approximation. We numerically draw…