Materials Literature
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X-band ESR powder studies have been done on the spin transition in Mn(2+)-doped [Fe(bpp)(2)][CF(3)SO(3)](2).H(2)O and [Fe(bpp)(2)][BF(4)](2) (bpp = 2,6-bis(pyrazol-3-yl) pyridine). The change in D value of Mn(2+) during the thermally induced high-spin (HS) <--> low-spin (LS) transition shows that the spin transition i…
A glass-forming, low molecular weight diaminobiphenyl compound with incorporated azo groups was synthesized. It exhibits a glass transition temperature well above room temperature (101 °C), which is explained in terms of molecular structure. Holographic birefringence gratings as well as surface gratings were produced…
Bulky substituents added to second-order nonlinear optical (NLO) chromophores inhibit intermolecular electrostatic interactions that attenuate electric poling induced macroscopic electrooptic activity. Such chromophore modification also improves chemical and photochemical stability and the processability of chromophor…
We study theoretically the adsorption of surfactant onto the interface of gas bubbles in creeping flow rising steadily in an infinite liquid phase containing surface-active agents. When a bubble rises in the fluid, surfactant adsorbs onto the surface at the leading edge, is convected by the surface flow to the trailin…
High molecular weight hyperbranched polyetherimides have been synthesized in a single-pot reaction in as little as 2.5 min from an easily synthesized and scalable AB 2 monomer using a rapid catalytic arylation method. NMR integration experiments and model compound studies revealed a degree of branching (DB) of 67% for…
We propose a genetic local search algorithm (GLSA) for the optimization design of diffractive optical elements (DOE's). This hybrid algorithm incorporates advantages of both genetic algorithm (GA) and local search techniques. It appears better able to locate the global minimum compared with a canonical GA. Sample case…
Single crystals of a novel titanium glycolate complex, Ti(OCH 2 CH 2 O) 2, have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, IR spectroscopy, thermal analysis (TG-DTA), and scanning electron microscopy (SEM). The titanium glycolate complex crystallizes in the monoclinic space…
The wetting behavior of P(S- b -I) and P(S- b -nBMA) thin films placed upon tunable P(S- r -MMA) brush surfaces is addressed. Homopolymer dewetting experiments show an increase in interfacial energy between PI and P(S- r -MMA) with increasing styrene fraction, while the interfacial energy dependence of PnBMA with brus…
The interaction of a nonrelativistic charged particle beam, travelling parallel to the surface of a sharp-edged dielectric wedge is analyzed. The general expressions for excitation probability are obtained for a beam moving along the direction of a symmetry axis, either outside or inside the dielectric wedge. The diel…
To date, most of the studies dealing with the magnetic properties of 4f-3d compounds have been limited to the case in which the 4f ion was Gd(III), with a pure spin ground state. For the lanthanide(III) ions with a first-order orbital momentum, the determination of the nature of the 4f-3d interaction is still a challe…
Crazing in thick polymer glass films and bulk glassy polymers is theoretically investigated. A simple microscopic model that treats an amorphous polymer at stresses above the yield stress as a viscous fluid with the scale-dependent surface tension is developed. Craze microstructural parameters including fibril diamete…
The vanadium silicalite (VS-2) catalyst was hydrothermally synthesized, and a molecular level characterization was carried out by means of in situ photoluminescence, XAFS, ESR, FT-IR, UV−vis, solid-state wide-line 51 V NMR, and XRD in the presence or absence of reactant molecules. These spectroscopic investigations of…
New hyperbranched poly(carbosilarylenes) are described that exhibit low glass transition temperatures and high thermal stabilities. The incorporation of Si−O−Si linkages into the branches leads to a polymer of increased flexibility but considerably lower thermal stability. The hyperbranched polymers are prepared via a…
The semicrystalline morphology of poly(3-hydroxy butyrate) (PHB)/poly(vinyl acetate) (PVAc) blends at four crystallization temperatures ( T c = 70, 90, 110, and 125 °C) was probed by small-angle X-ray scattering (SAXS). Morphological parameters including the crystal thickness ( l c ) and the amorphous layer thickness…
The synthesis of fourth-generation poly(amido−amine) (PAMAM) dendrimers having terminal groups partially or fully functionalized with thiol groups is described. These thiolated dendrimers form stable monolayers on planar Au substrates. X-ray photoelectron spectroscopy studies reveal that most of the thiol groups on de…
In this paper we show that hyperbranched polymers can be used as a host matrix for electrostatic entrapment of enzymes. Specifically, amine-functionalized glucose oxidase (GOx+) and horseradish peroxidase, as well as poly(amidoamine) dendrimer-modified horseradish peroxidase, reversibly sorb into polyanionic, hyperbra…
We propose that the low temperature discrepancy between simple d-wave models of the microwave conductivity and existing experiments on single crystals of YBCO can be resolved by including the scattering of quasiparticles from "holes" of the order parameter at impurity sites. Within a framework proposed previously, we…
To clarify the mechanism of cross-interfacial molecular transport and the role of subcritical cluster population in determining the kinetics of crystal nucleation, cluster dynamics calculations based on viscosity-governed rate coefficients are confronted with experiments on crystal nucleation in six stoichiometric oxi…
The synthesis of 2-phenylthieno[3,4-b]thiophene was carried out in two steps from 3,4-dibromothiophene and phenylacetylene. Electropolymerization of this monomer affords a novel low band gap (Egap) polymer that was characterized by cyclic voltammetry and electrochemistry. An Egap of ca. 0.85 eV was observed, which is…
Poly(vinyl alcohol) (PVA) was cyanoethylated by reaction with acrylonitrile in the presence of sodium hydroxide and quaternary ammonium halide. Quaternary ammonium halide, acting as a phase transfer catalyst, increases the degree of substitution (DS) of PVA. The DS also increased with increasing acrylonitrile concentr…