Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Mesoporous, high-surface-area zirconium(IV) oxide may be prepared by incorporation of cationic quaternary ammonium surfactants in the hydrous oxide and subsequent calcination of the inorganic/organic intermediate. The surfactants are incorporated by cation exchange at a pH above the isoelectric point of the hydrous ox…
We have discovered a solid, apparently amorphous phase of triphenyl phosphite to which the supercooled liquid converts, a phase distinct from both the glass and the crystal. To date, this is the clearest and best identified case of a first-order transition from a liquid to another apparently amorphous condensed phase.…
Lipases from porcine pancreas and from Pseudomonas cepacia catalyze the ring-opening polymerization of lactones. Polymerization of the four-membered β-butyrolactone yielded poly(3-hydroxybutyrate) in up to 89% yield with a degree of polymerization of 3−12. Polymerization of the four-membered β-propiolactone, the five-…
In order to obtain information on transport processes in ultrathin films of polyelectrolytes, we studied the time dependence of the fluorescence of a dye (FITC) attached to a polymer and embedded in a defined, variable depth inside the film by total internal reflection fluorescence (TIRF) spectroscopy. Adding a rhodam…
Phthalocyanines are macrocyclic compounds which possess a variety of properties of potential importance in advanced technologies. The article considers the development of phthalocyanine derivatives for deposition as thin films by the Langmuir–Blodgett method, spin-coating and self-assembly. Important aspects in this a…
The chemical effect of the zeolite 4A added to the intumescent ammonium polyphosphate (APP)–pentaerythritol (PER) system in a fire retardant (FR) ethylene–butyl acrylate–maleic anhydride terpolymer (LRAM3.5)-based formulation has been studied. Thermogravimetric (TG) analysis defines the different steps of the degradat…
The structure of acid sites in cobalt-substituted aluminophosphates (AlPOs) catalysts has been investigated, with EXAFS spectroscopy. Data obtained, using in situ methods, for the Co K-edge spectra of cobalt-substituted AlPO-5, AlPO-18, AlPO-36, and APSO-44 in as-prepared, calcined, and reduced states yield the local…
The purpose of this brief review is to describe some recent, preliminary attempts to prepare nanocomposites in which polymer chains thread through the cavities or channels of several types of inorganic materials, specifically zeolites, a mesoporous hexagonal form of silica, and silica nanotubes. One goal is to determi…
Abstract
SUMMARY An unconstrained 3-D micromagnetic model for magnetite grains with resolutions up to 23 × 23 × 63 is presented. The model has been used to investigate the magnetic domain states of submicron parallelepipeds with various elongations. The method of fast Fourier transformation (FFT) has been implemented in three…
The adsorption of CO on Co(0001) has been investigated in situ by polarization modulation infrared reflection absorption spectroscopy (PM-RAIRS), which has been applied for the first time in a study of a model system for a heterogeneous catalyst. The CO/Co(0001) system was studied in the pressure range from 10 -10 to…
In this perspective some general phenomena of ligand-stabilized transition-metal clusters and colloids are introduced before some recent results on the special behaviour of such particles in catalysis are given.
Abstract Polymerizations of lactides via cationic, anionic, and insertion mechanisms are described. The usefulness of these three mechanisms for preparative purposes is evaluated. The polymerization mechanisms initiated by Al‐alkoxides or Sn(II)‐2‐ethylhexanoate are discussed in more detail. Furthermore, the usefulnes…
The depression of the glass transition temperature of a wheat gluten film by water was studied by dynamic mechanical thermal analysis and differential scanning calorimetry. Wheat gluten film behaved as a typical amorphous polymer, and the large plasticizing effect of water did not fit simply on the prediction of the C…
Spread monolayers of poly(styrene)−poly(ethylene oxide) diblock copolymers (PS m −PEO n, m = 38, n = 90, 148, 250, and 445) have been studied at the air−water interface by measuring the surface pressure−area (π− A ) isotherms at several temperatures. The π− A isotherms exhibit several regions which can be ascribed to…
Abstract High purity and a large amount of β‐modification can be produced in polypropylene (PP) by adding a bicomponent β‐nucleator consisting of equal amounts of pimelic acid and calcium stearate. Wide angle X‐ray diffraction (WAXD), scanning electron microscopy (SEM), static tensile tests, Izod impact tests, and ins…
Hydrotalcites, which are anionic clays, have been synthesized by the sol−gel technique from magnesium ethoxide, aluminum tri-sec-butoxide, and aluminum acetylacetonate. Initially a colloidal solution is obtained which gels and is thermally stabilized. The local and average structure are studied comparing the electron…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTSoluble Alkyl-Substituted Poly(ethylenedioxythiophenes) as Electrochromic MaterialsAnil Kumar and John R. ReynoldsView Author Information Department of Chemistry, Center for Macromolecular Science and Engineering, University of Flor…
A new class of porphyrins in which intervening ethynyl moieties connect aryl groups to the porphyrin 5- and 15-positions is described. The synthesis and optical spectroscopy of five new compounds are reported: [5,15-bis[(4‘-dimethylaminophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), [5,15-bis[(4‘-methoxyphenyl)eth…
Polymerization of l -lactide in dichloromethane at 25 °C using an initiating system comprising tris(2,6-di- tert -butylphenoxy)yttrium and 2-propanol was first order in monomer and initiator. A propagation rate constant of 1.92 × 10 3 L mol -1 min -1 was determined using in situ UV spectroscopy. In the first step the…