Materials Literature
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Abstract The properties of ionic elastomers formed in the crosslinking with zinc peroxide are studied in compounds with varying proportions of carboxylic groups in the elastomeric matrix. At the temperature used, 150°C, preferentially ionic bonds were formed. The crosslinking densities and, correspondingly, the physic…
La2CoMnO6 perovskite manganite was synthesized by solid-state reaction. Rietveld refinement of powder x-ray diffraction data indicated that this compound crystallized with an orthorhombic structure containing distorted (Co/Mn)O6 octahedra (Pnma; a = 5.5 A; b = 7.2 A; c = 5.4 A. The dc magnetization and real part (x')…
Abstract Anionic ring‐opening polymerization of propylene oxide in the presence of potassium alcoholate initiator was accelerated by addition of the bulky phosphonium salt tetrakis[cyclohexyl(methyl)amino]phosphonium‐tetrafluoroborate. Dipropylene glycol (DPG) was partially deprotonated (5%) and used as an initiator f…
The electronic structure of the molecular solid $\mathrm{Ni}(\mathrm{tmdt}{)}_{2},$ the only well characterized neutral molecular metal to date, has been studied by means of first-principles density functional calculations. It is shown that these calculations correctly describe the metallic vs semiconducting behavior…
The influence of a bulky, strongly coupled substituent (benzoyl−phenyl−ethenyl, BPE) on the dynamics of the photoinduced ring-closure and ring-opening reactions of 1,2-bis[[2−methyl−thien−3−yl]]perfluorocyclopentene (BMTFP) in solution was investigated. UV/vis absorption spectroscopy in combination with chemical actin…
Abstract Rosin‐based polyester polyols were synthesized from a rosin–maleic anhydride adduct, diethylene glycol, and ethylene glycol with and without adding adipic acid and phthelic anhydride, in the presence of catalyst. Rigid polyurethane (PU) foams were prepared with these rosin‐based polyols and compared with foam…
A highly efficient functional mimic of a photosynthetic antenna−reaction center complex has been designed, synthesized, and studied spectroscopically. The antenna, consisting of four covalently linked zinc tetraarylporphyrins, (P ZP ) 3 −P ZC, has been coupled to a free-base porphyrin−fullerene artificial photosynthet…
The photophysical properties of the triple-stranded dimetallic helicates [Ln 2 (L C −2H) 3 ]·H 2 O (Ln = Nd, Sm, Dy, Yb) are determined in water and D 2 O solutions, and energy transfer processes are modeled for Sm III . The luminescence of Nd III, Sm III, and Yb III is sensitized by (L C −2H) 2-, but the energy trans…
Abstract A new metal‐free synthetic approach to the controlled ring‐opening polymerization (ROP) of lactide with nucleophilic phosphines as transesterification catalysts is described. P(Bu) 3 , PhPMe 2 , Ph 2 PMe, PPh 3 , and related phosphines are commercially available, inexpensive catalysts that generate narrowly d…
Abstract A new kind of polyol based on rape seed oil for use in rigid polyurethane foam was synthesized and characterized. The synthesis of such a polyol was divided into two steps. The first step was the hydroxylation of the double bonds existing in the long chains of the unsaturated aliphatic hydrocarbon of rape see…
The question how to introduce thermal fluctuations in the equation of motion of a magnetic system is addressed. Using the approach of the fluctuation-dissipation theorem we calculate the properties of the noise for both, the fluctuating field and fluctuating torque (force) representation. In contrast to earlier calcul…
Four plasma proteins have been shown to be able to mediate platelet adhesion to synthetic materials when they are adsorbed as purified proteins: fibrinogen (Fg), fibronectin (Fn), vitronectin (Vn), and von Willebrand factor (vWF). Among them, Fg is thought to play a leading role in mediating platelet adhesion to plasm…
We prepared the brownmillerite oxide Ca_{2-y}La_yCo_{2-x}Al_xO_5, and found that it was an n-type conductor. The thermopower and the resistivity of the single crystal are -90 microV/K and 68 mOhm cm along the ab direction at 440 K, which suggest relatively good thermoelectrical properties, compared with other transiti…
The photoluminescence (PL) quantum yield (QY) of CdSe nanocrystals during their growth under a given set of initial conditions increases monotonically to a certain maximum value and then decreases gradually. Such a maximum is denoted as a PL "bright point", which does not always overlap with the minimum point of the P…
Abstract Nucleophilic substitution of chlorine on plasticized poly(vinyl chloride) (PVC) was carried out using potassium iodide (KI) in the presence of a phase transfer catalyst (PTC) in aqueous media. Iodination was confirmed using energy dispersive X‐ray analysis (EDAX). The extent of iodination was studied with res…
The equilibrium speciation in the system pH+ + qMoO42− + rH2O2 + sSO42− ⇌ (H+)p(MoO42−)q(H2O2)r(SO42−)s in 0.300 M Na2(SO4) medium at 25 °C has been determined from potentiometric titration data in the ranges 2.0 ≤ pH ≤ 5.5, 5.00 ≤ [Mo]tot/mM ≤ 80.00, 0 ≤ [H2O2]tot/mM ≤ 245 and 273.07 ≤ [SO42−]tot/mM ≤ 320.20. Species…
Abstract This paper is the second part of a review of some of the controversial kinetic aspects of conventional thermal analysis (TA). In this part the physico‐geometric kinetics for the solid‐state reactions were examined. The main problems discussed are (1) problems in fitting kinetics data: the identification of th…
Abstract A series of modified natural rubber latexes (NRLs) grafted with poly(methyl methacrylate) (PMMA) were prepared by seeded emulsion polymerization with NRL as the seed polymer. Two different redox systems, cumene hydroperoxide (CHP)/tetraethylene pentamine (TEPA) and tert ‐butyl hydroperoxide ( t ‐BHP)/TEPA, we…
Abstract The phosphoric acid–pentaerythritol–melamine copolymer was selected as an intumescent flame retardant (IFR). The influence of dicromate acid–etching polypropylene (EPP) on the properties and compatibility of IFR/PP composites was studied. The results obtained from mechanical tests and SEM showed that EPP was…
Miscible block copolymer/homopolymer blends are typically prepared from homogeneous solutions in a nonselective solvent. During solvent removal and subsequent annealing, the molecular species comprising such blends organize in such fashion as to lower the system free energy and ideally attain thermodynamic equilibrium…