Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorOne-Dimensionally Periodic Dielectric Reflectors from Self-Assembled Block Copolymer−Homopolymer BlendsAugustine Urbas, Yoel Fink, and Edwin L. ThomasView Author Information Department of Materials Science and Engineering, M.I.T., Cambr…
We report the synthesis of six new dendrimers built around a [Ru(bpy) 3 ] 2+ -type core (bpy = 2,2‘-bipyridine) and bearing up to 24 4‘- tert -butylphenyloxy or 48 benzyl units in the periphery. The metallodendrimers were obtained by complexation of ruthenium trichloride or Ru(bpy) 2 Cl 2 with bipyridine ligands carry…
We simulate the phase separation of binary mixtures under shear in the presence of solid, mobile particles. We combine cell dynamical equations for the binary mixture with Langevin dynamics for the particles and carry out the simulations in two dimensions. One of the components preferentially wets the surface of the p…
Partially ordered micrometer-sized carbon tubes several centimeters in length have been prepared via a new chemical approach by the pyrolysis of composite fibers consisting of a thermally more stable polypyrrole (PPy) skin layer and a poly(ethylene terephthalate) core. The wall thickness of resultant hollow carbon tub…
Three- and four-arm poly(ethylene oxide) (PEOs) fractions have been synthesized to investigate the molecular shape dependence on polymer crystallization, melting, and annealing behaviors. Each arm in these star PEOs has a molecular weight (MW) of 2220 ( M a = 2220) and has been coupled using 1,3,5-benzene tricarbonyl…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTScreening of Optically Active Nickel Initiators for Enantioasymmetric Polymerization of γ-Benzyl Glutamate-N-CarboxyanhydrideJianjun Cheng and Timothy J. DemingView Author Information Departments of Materials and Chemistry, Universi…
The ambient temperature adsorption of acetonitrile (in its d 3 deuterated form, to avoid Fermi resonance band splitting in the analytical ν CN spectral region) was studied on pure γ-alumina, γ-alumina doped with two different amounts of sulfates, γ-alumina doped with Ca, and a Ca-doped alumina that was thermally trans…
Magnetic domain structure on the surface of the layer-structured ferromagnet La1.4Sr1.6Mn2O7 was observed in the temperature range from 37 to 97 kelvin with a scanning Hall probe microscope. The sensitivity to temperature of the domain structure changes was large relative to that in conventional ferromagnets. The stab…
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A series of poly(ethylene) (PE) films with different degrees of crystallinity was treated with a radio-frequency tetrafluoromethane (CF 4 ) gas plasma (48−49 W, 0.06−0.07 mbar, and continuous vs pulsed treatment). The etching behavior and surface chemical and structural changes of the PE films were studied by weight m…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTApplication of Calcium Acetylacetonate to the Polymerization of Glycolide and Copolymerization of Glycolide with ε-Caprolactone and l-LactidePiotr Dobrzyński, Janusz Kasperczyk, and Maciej BeroView Author Information Centre of Polym…
We report the observation of depletion-induced phase separation in a mixture of colloidal silica spheres and colloidal silica rods with light microscopy and confocal scanning laser microscopy. We show that very low rod concentrations are sufficient to induce sphere crystallization. This qualitatively agrees with theor…
By nanoblends, it is meant that the scale of dispersion of one polymer phase in the other is below 100 nm. A novel method was developed to prepare nanostructured blends (nanoblends) of polypropylene (PP) and polyamide-6 (PA-6) directly in a screw extruder. It consisted of polymerizing a monomer of PA-6, ε-caprolactam…
We investigate anharmonically coupled high- and low-frequency excitations in a planar lattice of adsorbed molecules interacting with phonons of a crystal. Dephasing of high-frequency local vibrations by low-frequency resonance modes is described in terms of temperature Green's function. The equations obtained are solv…
We develop mean-field kinetic equations for a lattice gas model of a binary alloy with vacancies (ABv model) in which diffusion takes place by a vacancy mechanism. These equations are applied to the study of phase separation of finite portions of an unstable mixture immersed in a stable vapor. Due to a larger mobility…
The influence of physical diffusion of the electroactive species on the mechanism of charge transport in chemically modified electrodes is analyzed for ion exchange and covalently attached redox polymers with explicit consideration of vacant sites. The appropriate flux equation for charge transport is derived using ph…
The mechanism of the Mur synthetases of peptidoglycan biosynthesis is thought to involve in each case the successive formation of an acyl phosphate and a tetrahedral intermediate. The existence of the acyl phosphates for the MurC and MurD enzymes from Escherichia coli was firmly established by their in situ reduction…
Introduction Assembly is a basic device of nature where a broad range of entities, spanning many levels of scale, interact across time and space to produce oberserved pattern. Entities such as individuals, phenotypes, populations, guilds, and higher levels of organization like hierarchical structures are all subject t…
Modeling of the (GSGAGA) n consensus sequence of the crystalline region of Bombyx mori silk fibroin revealed two novel conformations. One was a series of four-residue β-turns, consistent with published circular dichroic spectra and nuclear magnetic resonance data for the water-soluble silk I that is found in the abdom…
We report on the synthesis of nearly monodisperse phase-separated polymer latexes with a well-defined core−shell morphology. Styrene/diisopropenylbenzene and tert -butyl acrylate/ethylene glylcol-diacrylate were used for either the core or shell of the composite microgel particles. A major concern of the paper is the…