Materials Literature
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Diblock copolymers order into a variety of periodic morphologies when the constituent blocks are sufficiently incompatible. Previous studies have demonstrated that classical dispersion (spherical and cylindrical) and lamellar morphologies, as well as complex morphologies ( e.g., gyroid*, lamellar catenoid, and hexagon…
Titania coatings ranging from sub-monolayer to ≈7 nm thick have been deposited on silica by hydrolysis of titanium alkoxide precursors. Nonporous model silica particles of spherical shape were used as the support for titania. The ratio of titanium alkoxide to water and the dilution of the reactant mixture in ethanol c…
4-Nitrophenyl 4-[[2-[(2-methyl-1-oxo-2-propenyl)oxy]ethyl]oxy]benzoate (BEM) was synthesized and copolymerized with 4‘-[[[2-[(2-methyl-1-oxo-2-propenyl)oxy]ethyl]ethyl]amino]-4-nitroazobenzene (DR1M) in dioxane at 60 °C. BEM and DR1M copolymerize in a random fashion with reactivity ratios r DR1M = 0.82 and r BEM = 1.0…
We have observed what appears to be a first-order phase change from deeply supercooled liquid triphenyl phosphite at 1 atm to a rigid, “apparently” amorphous phase which we denote as the “glacial phase”. This is a new, crisper, and rather different addition to the examples of polyamorphism that have recently been stud…
Al-free Ti-β zeolite spontaneously nucleates and grows in a reaction mixture containing tetraethylammonium and fluoride ions at near neutral pH, and shows an enhanced crystallinity and thermal and hydrothermal stability as well as a significant hydrophobic character.
We use self-consistent mean field methods and analytical theory to determine the behavior of AB copolymers at the interface between two incompatible homopolymers, A and B. We calculate the reduction in interfacial tension, γ, resulting from the copolymers localizing at the A/B interface. We examine the effects of chai…
Gallium-doped zinc oxide powders have been prepared with electrical conductivities at 25 °C as high as 300 Ω - 1 cm - 1, more than 1000 higher than previously reported. All materials prepared can be represented as Zn 1 - x Ga x O, Zn 1 - y Ga y O 1+( y /2), or a combination of these two. For Zn 1 - x Ga x O, the room-…
End-functional aliphatic polyesters have been synthesized by ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) and lactides (LA). Polymerization initiated with any of the functional aluminum alkoxides of the general structure Et 3- p Al(OCH 2 X) p, where p = 1 and 3, obeys a living “coordination−insertion” me…
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.