Materials Literature
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To explore the ability of the “effective concentration” model to quantitatively predict the individual local dynamics of each component in miscible polymer blends, three model systems [polystyrene/poly(vinyl methyl ether), polystyrene/poly( o -chlorostyrene), and poly(vinyl methyl ether)/poly( o -chlorostyrene)] are s…
Abstract The hot‐wire parallel technique standardized for determining the thermal conductivity of ceramic materials was employed in the determination of the thermal properties of polymers. For these materials, additional care must be taken considering the low melting point of polymers, when compared with that for cera…
Various 109Ag NMR techniques are used to study silver diffusion in silver iodide/silver phosphate glasses. In particular, for the first time, four-dimensional (4D) NMR is applied on solid ion conductors. All experiments consistently show that silver dynamics are governed by a very broad, continuous distribution of cor…
Abstract A suspension of non‐neutrally buoyant, large, nearly monodisperse spheres is studied both in batch sedimentation and in shear between concentric rotating cylinders. We apply a continuum constitutive equation based on the diffusive flux model augmented with buoyancy terms derived by Acrivos and coworkers and d…
The efficacy of a sonophotochemical reactor coupling ultrasonic irradiation with photocatalytic oxidation has been evaluated using formic acid degradation as the model reaction. The reactor used in the present work is a hexagonal flow cell irradiated with multiple-frequency transducers placed at the wall of the reacto…
We report the photophysical characterization of the two tautomers ( 1e and 1i ) of 5,10,15,20-tetraphenyl N-confused free-base porphyrin, potential building blocks in assemblies designed for artificial photosynthesis, using a combination of steady state and time-resolved techniques. Tautomer 1e was found to have a sig…
The 3,5-di-tert-butyl-catecholato and 9,10-phenanthrenecatecholato adducts of the cobalt-tetraazamacrocycle complex Co(Me(4)cyclam)(2+) (Me(4)cyclam = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) were synthesized and oxidized. The oxidation reaction products were isolated in the solid state as hexafluoropho…
The inferred crystallographic class of circumstellar silicon carbide based on astronomical infrared spectra is controversial. We have directly determined the polytype distribution of circumstellar SiC from transmission electron microscopy of presolar silicon carbide from the Murchison carbonaceous meteorite. Only two…
Microfibrous self-aggregation of chromophoric groups of porphyrin and/or pyrene substituted by didodecyl l -glutamic acid in organic media is confirmed by transmission electron microscopic (TEM) observation. Chromophoric probes of porphyrin and pyrene moieties enable evaluation of their assembling behavior photophysic…
Low-field and high-field transport properties of carbon nanotubes/polymer composites are investigated for different tube fractions. Above the percolation threshold ${f}_{c}\ensuremath{\sim}0.33%,$ transport is due to hopping of localized charge carriers with a localization length $\ensuremath{\xi}\ensuremath{\sim}10\e…
Several unexpected and intriguing magnetic phenomena have been observed in the ${\mathrm{Gd}}_{5}{\mathrm{Ge}}_{4}$ compound. First, below \ensuremath{\sim}130 K, ${\mathrm{Gd}}_{5}{\mathrm{Ge}}_{4}$ is antiferromagnetic in a zero magnetic field, but it can be transformed into the ferromagnetic state both irreversibly…
Two series of novel fully conjugated oligomers, oligothiophene-functionalized 9,9'-spirobifluorene derivatives, have been developed in this contribution. First, four 9,9'-spirobifluorene bromide derivatives (compounds 1a-d) are prepared through various synthetic routes. Oligothiophene derivatives with or without subst…
The structure of a bis-urea based reversible polymer is investigated using capillary viscosimetry, infrared spectroscopy, small-angle neutron scattering, and rheology. The highly viscoelastic solutions obtained in toluene are due to the formation of long and rigid fibrillar species. The cross section of these wires is…
The effect of sodium sulfonate functionalization of poly(butylene terephthalate) (PBT) on the properties of PBT/montmorillonite composites was studied. The results of the study clearly showed that organic modification of montmorillonite clay coupled with the modification of PBT with low levels (1.0−5.0 mol %) of −SO 3…
Abstract Poly(ethylene terephthalate) waste was depolymerized with ethylene glycol in the presence of different catalysts, two conventional metal catalysts (zinc acetate and lead acetate) and two alkalies (sodium carbonate and sodium bicarbonate). The resulting monomer bis(2‐hydroxy ethylene terephthalate) was charact…
Abstract Radiation can induce chemical reactions to modify polymers even when they are in the solid state or at a low temperature. Radiation crosslinking can be easily adjusted by controlling the radiation dose and is reproducible. The finished product contains no residuals of substances required to initiate the chemi…
This study of the one dimensional Su-Schrieffer-Heeger model in a weak coupling perturbative regime points out the effective mass behavior as a function of the adiabatic parameter $ω_π/J$, $ω_π$ is the zone boundary phonon energy and $J$ is the electron band hopping integral. Computation of low order diagrams shows th…
We present a study of the one dimensional Su-Schrieffer-Heeger model Hamiltonian by a diagrammatic perturbative method in the weak electron-phonon coupling regime. Exact computation of both the charge carrier effective mass and the electron spectral function shows that electrons are good quasiparticles in the adiabati…
Tight binding molecular dynamics simulations, with a non orthogonal basis set, are performed to study the fragmentation of carbon fullerenes doped with up to six silicon atoms. Both substitutional and adsorbed cases are considered. The fragmentation process is simulated starting from the equilibrium configuration in e…
Magnetization, susceptibility, and specific heat measurements were made on a single crystal of ${\mathrm{La}}_{0.75}{\mathrm{Sr}}_{0.25}{\mathrm{MnO}}_{3}.$ The ferromagnetic-to-paramagnetic phase transition was found at 346 K and four critical exponents were measured as: $\ensuremath{\alpha}=0.05\ifmmode\pm\else\text…