Materials Literature
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Abstract Polyester‐based polyurethanes with embedded nanosilica particles were prepared. The viscosity of polyester resins without and with nanosilica was determined by rheoviscometry. The morphology and mechanical and optical properties of the polyurethane coatings were studied intensively with a transmission electro…
The use of 1,3,5-triaminocyclohexane (tach) as a capping ligand in generating metal-cyanide cage clusters with accessible cavities is demonstrated. The precursor complexes [(tach)M(CN)(3)] (M = Cr, Fe, Co) are synthesized by methods similar to those employed in preparing the analogous 1,4,7-triazacyclononane (tacn) co…
A variety of three-constituent superlattice patterns were made in atomic layer-by-layer films, with patterns breaking inversion symmetry giving effective permanent bias fields ranging up to about 200 kV/cm. Dielectric constants at room temperature were nearly 10(3), with loss tangents under 0.01. Most of the response…
The reaction of AgX, where X = trifluoroacetate (CF(3)CO(2)(-), tfa), nitrate (NO(3)(-)), trifluoromethanesulfonate (triflate, CF(3)SO(3)(-), OTf), hexafluorophosphate (PF(6)(-)), or perchlorate (ClO(4)(-)), with 2,2',3' '-tripyridylamine (tpa) yields five novel silver(I) complexes, which have been structurally charac…
A series of new polypseudorotaxanes were synthesized in high yields when the middle poly(ethylene oxide) (PEO) block of poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) (PPO-PEO-PPO) triblock copolymers was selectively recognized and included by alpha-cyclodextrin (alpha-CD) to form crystalline inclusi…
A method based on the kinetics of adatoms on a growing surface under epitaxial growth at low temperature in (1+1) dimensions is proposed to obtain a closed form of local growth equation. It can be generalized to any growth problem as long as diffusion of adatoms govern the surface morphology. The method can be easily…
We analyze the structure of the energy landscape of a well-relaxed 1000-atom model of amorphous silicon using the activation-relaxation technique (ART nouveau). Generating more than 40,000 events starting from a single minimum, we find that activated mechanisms are local in nature, that they are distributed uniformly…
We comment on a recent paper [D. Schultz et al, Phys. REv. Lett. 90, 015501 (2003)]. We argue that a highly systematical investigation is needed to determine the most stable structures of both pristine and N-substituted fullerenes.
We present x-ray absorption and emission experiments and ab initio calculations showing that the size of carbon diamond must be reduced to at least 2 nm, in order to observe an increase of its optical gap, at variance with Si and Ge where quantum confinement effects persist up to 6-7 nm. In addition, our calculations…
In this work a completely novel photochromic mechanism exhibited by an indeno-fused naphthopyran (chromene) is presented. The studied molecule is the first case of a chromene-type compound exhibiting both photochromism and thermochromism. These phenomena were investigated in ethanol. Thermochromism was detected by mon…
Normal-emission photoelectron spectra of a clean Cr(001) were measured at room temperature with photon energies from 24 to 70 eV. The periodicity of the energy-band dispersion along [001] direction normal to the surface is compatible with that of an antiferromagnetic structure rather than a paramagnetic one. One of th…
23Na MQMAS and 1H↔23Na CP/MAS NMR techniques have been used to study the variation of the sodium coordination during the hydration processes of the layered sodium disilicates SKS-5 and SKS-6. Three new types of sodium ions, with different local coordination environments, were identified and correspond to sodium ions c…
The effective anisotropy field and the saturation magnetostriction constant are presented as a function of the annealing parameters for Fe 93− x − y Zr 7 B x Cu y ( x = 6, 8 and y = 0, 1, 2) samples. The results obtained for these magnetic properties are interpreted in terms of microstructure–magnetization interaction…
We study freely suspended films of smectic C* liquid crystalline gels by means of polarizing microscopy. The gel point of the system is determined from the suppression of flow in the films. The network of hydrogen bonds is mechanically fragile but stabilizes orientation patterns of the sample, in particular it stores…
We prepared bismuth sodium titanate (Bi 0.5 Na 0.5 TiO 3 ) ultrafine powders by the sol-gel method. The dielectric properties of the pressed pellets and fired ceramics with different grain sizes as a function of temperature at various frequencies were studied. With decreasing grain size, the dielectric anomaly around…
Abstract A kind of LLDPE (linear low density polyethylene)/LDPE (low density polyethylene) thin film for farm applications was subjected to accelerated and natural weathering. Carbonyl group, melting point, tensile elastic modulus, and high‐temperature shearing modulus of weathered films were investigated as function…
Monolayers of third-generation amphiphilic poly(amido amine) (PAMAM) dendrimer were prepared at the air/water interface and then were successfully transferred onto silicon wafers by a horizontal lifting method. A comprehensive characterization of the PAMAM monolayers was made, structurally and dynamically, by scanning…
Abstract Polypropylene (PP) and acrylonitrile–butadiene–styrene blends of different composition were prepared using a single‐screw extruder. The binary blend of PP/ABS was observed to be incompatible and shows poor mechanical properties. PP‐ g ‐2‐hydroxyethyl methacrylate (2‐HEMA) was used as a compatibilizer for the…
Poly( dl -lactic acid) (PLA) materials have been surface engineered via an entrapment method to present high densities of poly(ethylene glycol) (PEG) to control protein adsorption. The resultant change in physical properties was characterized on the surface and bulk of the entrapped PEG/PLA system through microthermal…
The synthesis of singly and doubly bridged bis-TTF containing a 2,6-bis(methylthio)pyridine group as a linker and potentially usable as a ligand for paramagnetic transition metal complexes is reported. Cyclisation leading to doubly bridged bis-TTF has been achieved without using the high dilution technique generally e…