Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTMechanical α-Process in Polyethylene†Yongfeng Men, Jens Rieger, Hans-Friedlich Endeler, and Dieter LilgeView Author Information BASF Aktiengesellschaft, Polymer Physics, 67056 Ludwigshafen, Germany Basell Polyolefine GmbH, R&D, 6592…
The intercalation reaction of polyoxyethylene sulfate (PEGS) with Mg−Al−nitrate [Mg−Al−NO 3 ] layered double hydroxide (LDH) was investigated by using X-ray diffraction, infrared spectroscopy, and transmission electron microscopy (TEM). X-ray diffractograms showed that the basal spacing of the [Mg−Al−NO 3 ] LDH with P…
Memory effects in propylene/ethylene copolymer (cPP) systems containing different amounts of dibenzylidene sorbitol (DBS) have been studied using wide-angle X-ray scattering techniques. It has been observed that shear flow deformation applied to the melt state containing small amounts of DBS is templated into the crys…
Using in-situ small- and wide-angle X-ray scattering, we demonstrate that bundles with smectic ordering are produced by a step shear in a supercooled isotactic polypropylene melt. This occurs well before any formation of crystals. The period of the smectic mesophase is about 3.8 nm and depends neither on the shear rat…
Reactions of pyrrole (2) or 1-methylpyrrole (4) with readily available N-acylbenzotriazoles 1a-g (RCOBt, where R = 4-tolyl, 4-nitrophenyl, 4-diethylaminophenyl, 2-furyl, 2-pyridyl, 2-indolyl, or 2-pyrrolyl) in the presence of TiCl(4) produced 2-acylpyrroles 3a-g and 5a-g in good to excellent yields. 1-Triisopropylsily…
The microstructure of maleic anhydride (MA) grafted polyethylene (PE), MA- g -PE, has been successfully characterized by high-resolution NMR and FT-IR spectroscopy. The carbonyl asymmetric and symmetric stretchings of MA- g -PE exhibit lower shifts with an increase in the grafting degree of MA, suggesting stronger ind…
Reversible addition−fragmentation chain transfer (RAFT) is a versatile, controlled free radical polymerization technique that operates via a degenerative transfer mechanism in which a thiocarbonylthio compound acts as a chain transfer agent. The subsequent reduction of the dithioester end groups to thiols allows the p…
A simple expression for the composition dependence of the Flory-Huggins interaction parameter of polymer/solvent systems reported earlier is used to model the demixing of polymer solutions into two liquid phases. To this end the system specific parameters zeta and ny of that approach are calculated as a function of te…
Green nanocomposites based on renewable plant oils have been developed. Curing of epoxidized plant oils in the presence of organophilic montmorillonite produced triglyceride−clay nanocomposites showing flexible property. A nanocomposite with homogeneous structure was obtained, in which silicate layers of the clay were…
Dodecanethiol-stabilized gold nanoparticles with similar average size organize into different superlattice structures depending upon the method of preparation of the nanocrystals. Particles synthesized by the inverse micelle technique preferentially assemble into face-centered cubic (fcc) structures with long-range tr…
Prussian blue (PB) nanoparticles protected by poly(vinylpyrrolidone) (PVP) were prepared by mixing aqueous Fe2+, Fe(CN)63-, and PVP solutions together and were characterized by UV-vis, IR, XRPD, and TEM. Averaged dimensions of the nanoparticles were controlled between 12 and 27 nm depending on initial Fe ion concentra…
We have studied the optical properties of metallic nanoparticles with arbitrary shape. We performed theoretical calculations of the absorption, extinction, and scattering efficiencies, which can be directly compared with experiments, using the discrete dipole approximation (DDA). In this work, the main features in the…
The extinction coefficient per mole of nanocrystals at the first exitonic absorption peak, ε, for high-quality CdTe, CdSe, and CdS nanocrystals was found to be strongly dependent on the size of the nanocrystals, between a square and a cubic dependence. The measurements were carried out using either nanocrystals purifi…
We present a comprehensive study of minority carrier lifetime and recombination mechanisms in n-InP single crystals. The study is based on steady state and time-resolved photoluminescence measurements in a wide temperature range (15–300 K). Various recombination and trapping mechanisms are analyzed and compared in ord…
An efficient green chemistry approach to the synthesis of N-substituted piperidones and piperidines was developed and applied to the synthesis of 1-(2-pyridinylmethyl)-piperidin-4-one, 1, a key starting material for the synthesis of LY317615, an antiangiogenic agent currently under development at Eli Lilly and Company…
The evolution of the Lewis acidity of a MgAl hydrotalcite sample (Mg/Al ratio of 4) during thermal treatment in vacuo at different temperatures was followed by means of FTIR spectroscopy of CO adsorbed at 85 K. The materials were also characterized by XRD, TG-DTA, and BET measurements. It was found that samples activa…
It is known that chalcogenide glasses, in general, are p-type semiconductors. This is attributed to the following two reasons. (i) The number of electrons excited above the conduction band mobility edge is smaller than the number of holes excited below the valence band mobility edge. (ii) The lifetime of the free hole…
Analytical expressions are derived as a first-order approximation for the elastic displacement fields, including both phonon- and phason-type components, induced by spherical inclusions in icosahedral quasicrystals (IQCs). The phonon-type component obtained is the same as that for a spherical inclusion in conventional…
Upon aging, a collapsed long chain evolves from a crumpled state to a self-entangled globule which can be thought of as a large knot. Swelling of an equilibrium globule in good solvent is a two-step process: (i) fast swelling into an arrested stretched structure with conserved entanglement topology followed by (ii) sl…
Abstract The acid‐catalyzed controlled hydrolytic polycondensation of tetraethoxysilane (TEOS) provided polyethoxysiloxanes with weight‐average molecular weights of 2300–11,700, which depended on the reaction molar ratios of the water, catalyst, and solvent to TEOS. They were soluble in common organic solvents and sta…