Materials Literature
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Two methods for the addition of pendent dialkyl phosphonate units onto aryloxyphosphazenes, at both the polymeric and cyclic trimer levels, are described. Sodium organophosphites or halogenated organophosphates were used as the phosphonating agents and were allowed to react with bromomethylene- or lithio-functionalize…
Microporous amorphous metallosilicates designated as Mg−Si−O and Al−Si−O, with a very narrow pore size distribution around 6 Å diameter, typical surface areas ranging from 350 to 650 m 2 /g, and loadings of well-dispersed metal oxide (up to about 10 wt % metal) result from the controlled calcination of magnesium and a…
We report the synthesis of poly( p -phenylene vinylene) (PPV), a polyconjugated polymer, in nanotube and nanorod shapes, and carbonized products derived therefrom. PPV tubes and rods could be prepared on the inner surface of or inside the nanopores (10−200 nm diameter) in alumina or polycarbonate membrane filters by t…
The complex bis-5,5‘-(1,3-propanediyldiimino)-2,2-dimethyl-4-hexen-3-onato samarium bis(trimethylsilyl)amido is a solvent- and halide-free anhydrous, monomeric lanthanide Schiff base complex. It was synthesized from triflate-derived homoleptic Sm[N(TMS)2]3 and isolated in excellent yields and analytical purity. For la…
A detailed analysis is made of the statistics and diffraction by a general, finite, two-dimensional ideal paracrystal. The statistics of the diagonal chain through the ideal paracrystal are derived, and the special cases of square and hexagonal ideal paracrystals are considered. Expressions for the diffraction are der…
Abstract Immiscible blends of recycled poly(ethylene terephthalate) (R‐PET), containing some amount of polymeric impurities, and high‐density polyethylene (R‐PE), containing admixture of other polyolefins, in weight compositions of 75 : 25 and 25 : 75 were compatibilized with selected compatibilizers: maleated styrene…
Raman scattering and ${}^{31}\mathrm{P}$ NMR results show that the backbone of binary ${\mathrm{P}}_{x}{\mathrm{Se}}_{1\ensuremath{-}x}$ glasses is composed of ${\mathrm{Se}}_{n}$-chain fragments, pyramidal ${\mathrm{P}(\mathrm{S}\mathrm{e}}_{1/2}{)}_{3}$ units, quasitetrahedral ${\mathrm{S}\mathrm{e}=\mathrm{P}(\math…
Abstract The graft copolymerization of three vinyl monomer species, acrylonitrile (AN), acrylamide (AAm), and acrylic acid (AA), onto starch was carried out with ceric salt (Ce salt) as an initiator. With 3 mmol/L Ce salt, the monomer activity onto starch decreased in the following order: AN > AAm > AA. Grafting…
We report on a magnet exhibiting an inverted magnetic hysteresis loop, i.e., the magnetization becomes negative in the decreasing part even when the applied field is still positive, while the magnetization becomes positive in the increasing part when the applied field is still negative. The key to obtaining this unusu…
The structure of a decagonal Al72Ni20Co8 quasicrystal with space group P10(5)/mmc has been determined on the basis of a single-crystal X-ray data set using the five-dimensional description. The best-fit model structure based on a cluster model having lower symmetry than the decagonal symmetry with 103 parameters gives…
Sol−gel polymerization of organotrialkoxysilanes RSi(OR‘) 3 and formation of silsesquioxane (SSQO) structures was followed using SEC, 29 Si NMR, and both small- and wide-angle X-ray scattering. Evolution of the SSQO structure is controlled by the competition between intermolecular polycondensation and cyclization. A s…
Abstract An elastomeric polyurethane/clay (PU/clay) nanocomposite based on poly(propylene glycol) (PPG), glycerol propoxylate, and toluene‐diisocyanate (TDI) was synthesized by intercalative polymerization technology. The results of wide angle X‐ray diffraction (WAXD) studies showed that the gallery distance of the cl…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTThermally and Photochemically Triggered Self-Assembly of Peptide HydrogelsJoel H. Collier, Bi−Huang Hu, Jeffrey W. Ruberti, Jerry Zhang, Pochi Shum, David H. Thompson, and Phillip B. MessersmithView Author Information Northwestern University Biomedical Engineering Depa…
We report the polarized optical absorption spectra of single-walled 4 A carbon nanotubes arrayed in the channels of an AlPO (4)-5 single crystal. When the light electric field (E) is polarized parallel to the tube direction (c), the spectra display a sharp peak at 1.37 eV, with two broadbands at 2.1 and 3.1 eV. In the…
Abstract Crosslinked sodium polyacrylate as a superabsorbent was prepared by inverse suspension polymerization with cyclohexane as the continuous phase and sorbite anhydride monostearic acid ester (span‐80) as the dispersant. The crosslinking degree was regulated by NaOH. The distilled water absorbency (WA) of the pol…
The magnetic susceptibilities $\ensuremath{\chi}$ versus temperature T of powders and single crystals of the ambient-pressure (AP) and high-pressure (HP) phases of $(\mathrm{VO}{)}_{2}{\mathrm{P}}_{2}{\mathrm{O}}_{7}$ are analyzed using an accurate theoretical prediction of $\ensuremath{\chi}{(T,J}_{1}{,J}_{2})$ for t…
Using Monte Carlo simulations and a mean-field theory, we study domain growth in a driven lattice gas. Mediated by a single vacancy, two species of particles (``charges'') unmix, so that a disordered initial configuration develops charge-segregated domains which grow logarithmically slowly. An order parameter is defin…
We have performed a first-principles study of the structural and vibrational properties of the three low-pressure (cubic, tetragonal, and especially monoclinic) phases of ZrO2, with special attention to the computation of the zone-center phonon modes and related dielectric properties. The calculations have been carrie…
A variety of fullerene molecules are found to be fully packed in the interior space of a single-wall carbon nanotube (SWNT) and form a novel one-dimensional crystal with a regular intermolecular distance. Using electron diffraction, we have successfully measured the ``lattice constants'' for these crystals of various…
We prepared polycrystalline samples of NaCo2-xMxO4 substituted for the Co site by other 3d or 4d elements (M=Mn,Cu, Zn, Ru, Rh, and Pd). While some of the elements (M=Mn,Ru and Rh) act as a strong scatterer to give rise to a rapid increase in resistivity, the others (M=Cu, Zn and Pd) do not deteriorate the electric co…