Materials Literature
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Dendronized linear polymers are prepared from dendritic azides and poly(vinylacetylene) using "click chemistry." The Cu(I)-catalyzed Huisgen [2 + 3] cycloaddition is quantitative up to the third generation.
We demonstrate that graphite phonon dispersions have two Kohn anomalies at the $\ensuremath{\Gamma}\mathrm{\text{\ensuremath{-}}}{E}_{2g}$ and $\mathbf{K}\mathrm{\text{\ensuremath{-}}}{A}_{1}^{\ensuremath{'}}$ modes. The anomalies are revealed by two sharp kinks. By an exact analytic derivation, we show that the slope…
Thermal diffusivity has been investigated in ordered double perovskite Sr 2 FeMoO 6 by means of transient surface grating technique in the temperature range of 300–450 K. The thermal diffusivity shows an appreciable decrease from 39 mm 2 /s at 300 K to 37 mm 2 /s at 360 K in the ferromagnetic phase, and then steeply d…
Monte Carlo molecular simulations of the hydration of K-saturated Wyoming-type montmorillonite at constant stress in the NPzzT ensemble and at constant chemical potential in the grand canonical muVT ensemble, under basin-like conditions of 353 K and 625 bar, show a strong tendency of the K+ ions to adhere to the silox…
We present extensive simulations modeling the casting of multiblock polymer films by evaporation. The domain structure of the resulting film is strongly affected by varying the relative stiffness of the coblocks. The morphology changes from a bicontinuous lamellar phase when both blocks are flexible to a small-scale p…
We perform extensive simulations of a binary mixture Lennard-Jones system subjected to a temperature jump in order to study the time evolution of fluctuations during aging. Analyzing data from 1500 different aging realizations, we calculate distributions of inherent structure energies for different aging times and con…
Abstract The ring‐opening polymerization of L ‐lactide initiated by single‐component rare‐earth tris(4‐ tert ‐butylphenolate)s was conducted. The influences of the rare‐earth elements, solvents, temperature, monomer and initiator concentrations, and reaction time on the polymerization were investigated in detail. No r…
Abstract Polymerization rates were proportional to initial Sn(Oct) 2 concentration at low [Sn(Oct) 2 ] 0 /[PrOH] 0 values, but began to level off at higher values. When [Sn(Oct) 2 ] 0 /[PrOH] 0 was significantly greater than unity, the opposite behavior occurred. Tin(II) alkoxide concentration became limited by the in…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTStar-Shaped Polymer Synthesis by Anionic Polymerization of Propylene Sulfide Based on Trifunctional Initiator Derived from Trifunctional Five-Membered Cyclic DithiocarbonateAkane Suzuki, Daisuke Nagai, Bungo Ochiai, and Takeshi Endo…
Cobalt(II) salts react with H2O2 in the presence of 2 equiv of tetramethylethylenediamine (tmen) to produce a stable sideways bonded mononuclear peroxo complex [Co(tmen)2O2]ClO4 which has been characterized chemically and by a single crystal X-ray determination. This is the first such tetraaminecobalt(III) complex, in…
The synthesis, chemical characterization, and liquid crystalline behavior of two new series of poly(propyleneimine) (DAB) codendrimers are described. Both series were obtained by grafting onto the fourth-generation dendrimer (DAB−(NH 2 ) 32 ) various proportions of two types of promesogenic units: one of them laterall…
A method of determining the set of four order parameters S , D , P , and C for a ferroelectric liquid crystal, using complementary results for different sample geometries, is presented. IR measurements have been performed for homeotropic, planar heterogeneous and, planar homogenous sample geometries. Orientational ord…
Er 3+ -doped strontium–lead–bismuth glasses for developing potential upconversion lasers have been fabricated and characterized. Under 975 nm excitation, intense green and red emissions centred at 525, 546, and 657 nm, corresponding to the transitions 2 H 11/2 → 4 I 15/2 , 4 S 3/2 → 4 I 15/2 , and 4 F 9/2 → 4 I 15/2 ,…
We report the synthesis, characterization, and properties of a new class of hole−transport dyes, poly(dithienylisothianaphthene phenyldiamine)s (poly-DTITNPDs). These polymers are characterized by the presence of a low band gap isothianaphthene (ITN) and triarylamine units in the main chain. A modified Ullmann polycon…
A one-phase route has been developed for the synthesis, under strongly acidic conditions with cationic surfactants, of mesoporous silica nanofibers with controlled internal pore architectures. The diameters of the fibers range from 50 to 250 nm, and the lengths are up to millimeters. The nanofibers can have either a l…
The morphology and electronic structure of Pd clusters grown on oxidized yttrium surfaces are investigated by scanning tunneling microscopy and ultraviolet photoelectron spectroscopy. The hydrogen sorption mediated by the Pd clusters is determined from the optically monitored switching kinetics of the underlying yttri…
Abstract The chemical degradation of an uncrosslinked pure fluoroelastomer (FKM; Viton A) in an alkaline environment (10% NaOH and 80 °C) was investigated. Scanning electron microscopy images showed that on a microscopic level, significant degradation substantially increased the surface roughness after prolonged expos…
Silica encapsulation of nanoparticles has had important applications in areas as diverse as catalyst support in heterogeneous processes to controlled drug release. Current methods of production often require stringent conditions which can lead to degradation of the encapsulated material. Recently, we have developed a…
We implemented the heterodyne near-field scattering (HNFS) technique [Appl. Phys. Lett. 81, 4109 (2002)]], showing that it is a fairly valid alternative to traditional elastic low-angle light scattering and quite suitable for studying complex fluids such as colloidal systems. With respect to the original work, we adop…
Using selective laser extraction technique combined with sensitive ion-counting mass spectrometry, we have analyzed the isotopic structure of fission noble gases in U-free La-Ce-Sr-Ca aluminous hydroxy phosphate associated with the 2 billion yr old Oklo natural nuclear reactor. In addition to elevated abundances of fi…