Materials Literature
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Low thresholds (∼500 W/cm2) for amplified spontaneous emission (ASE) are reported in films of soluble poly(paraphenylene vinylene)-based conjugated polymer blends. Efficient Förster energy transfer from the absorbing host polymer to the emitting guest polymer is observed. Emission in the blends originates predominantl…
A single bubble in water is excited by a standing ultrasound wave. At high intensity the bubble starts to emit light. Together with the emitted light pulse, a shock wave is generated in the liquid at collapse time. The time-dependent velocity of the outward-traveling shock is measured with an imaging technique. The pr…
In the literature, the Schottky emission equation is widely used to describe the conduction mechanism in perovskite-type titanate thin films. Though the equation provides a good fit to the leakage current data, the extracted values of the Richardson and dielectric constants are inconsistent with their experimental val…
Well-aligned bundles of single-wall carbon nanotubes under tensile stresses were observed to fracture in real-time by transmission electron microscopy. The expansion of elliptical holes in the polymer matrix results in a tensile force in bridging nanotubes. The polymer matrix at both ends of the bundles deforms extens…
Although the elastic properties of a carbon nanotube are nearly independent of wrapping indices, we show that the onset of plastic deformation depends very strongly on the wrapping index. An $(n,0)$ nanotube has an elastic limit nearly twice that of an $(n,n)$ tube with the same radius. Such great variation has import…
We present simulations of the dynamic and temperature dependent behavior of Micro-Electro-Mechanical Systems (MEMS) by utilizing recently developed parallel codes which enable a coupling of length scales. The novel techniques used in this simulation accurately model the behavior of the mechanical components of MEMS do…
We show that the lattice Boltzmann formalism can be used to describe wave propagation in a heterogeneous media, as well as solid-body-like systems and fracture propagation. Several fundamental properties of real fractures (such as propagation speed and transition between rough and smooth crack surfaces) are well captu…
Successive passes through an extruder can modify the melt morphology of low-density polyethylene (LDPE) by applying a shearing process. The major effects of shear modification are to decrease the elastic properties, as evidenced by the decrease in extrudate swell at the exit of a capillary and in melt viscosity at a l…
In this paper, we present, for the first time, the magnetic properties of Cd 1 - y Mn y S nanocrystals of average size (4 nm) at various compositions, y . We demonstrate that the Mn−Mn interactions are markedly enhanced compared to the bulk material. As in the bulk phase, the photoluminescence and the EPR hyperfine st…
Using low-angle laser light-scattering (LALLS) and multiangle laser light-scattering (MALLS) techniques, absolute molar mass averages were determined for a wide variety of polymers in the Methocel™ product line produced by The Dow Chemical Company. These data were correlated to GPC molar mass averages obtained from co…
Size distribution information was used to monitor time-dependent agglomeration in aqueous solutions of a high molecular mass polyacrylamide. Although the individual polymer molecules had diameters in the order of 0.4 μm, a high number of agglomerates were seen that may contain four to six polymer chains. As the soluti…
Two sets of organotin compounds, that is, one having dibutyl and the other dioctyl groups each with a varying length of a carboxyl group attached to a tin atom, were studied as catalysts for the polycondensation of room temperature vulcanization of hydroxyfunctional polydimethylsiloxane (HOPDMS). The experiments were…
The crystal structure and the morphology of poly(ethylene oxide) (PEO)−2-methyl resorcinol (MRES) supramolecular complexes are investigated by differential scanning calorimetry and wide-angle and small-angle X-ray scattering. Depending on the MRES content, two molecular complexes with different stoichiometries are obs…
Polypyrrole (PPY) films with a thickness of 3–4 μm were obtained by chemical oxidation of pyrrole (PY) at the interface of chloroform and water with an oxidant (NH4)2S2O8. The films were compact and could be removed with a solid plate. The quality and compositions of these films varied with the molar ratios of the mon…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOptoelectronic Properties and Memories Based on Organic Single-Crystal Thin FilmsChong-yang Liu and Allen J. BardView Author Information Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712 Cite this: Acc. Chem. Res. 1999, 32, 3, 2…
Agrowastes and woodflour are a potential and attractive alternative of cheap reinforcement for brittle polymeric materials because they can reduce costs and, at the same time, improve certain properties. On the other hand, their high moisture sorption and low microbial resistance are disadvantages that need to be cons…
Phase-separated blend films were prepared with the solution casting method from poly(L-lactide) (PLLA) and poly(ε-caprolactone) (PCL) with different PLLA contents [XPLLA (w/w) = PLLA/(PCL + PLLA)] and their biodegradation was investigated in soil up to 20 months by gravimetry, gel permeation chromatography, tensile te…
The kinetics of oxygen chemisorption on resin chars were investigated in this study. The Elovich equation was employed to facilitate the interpretation of the chemisorption process. It was found that the activation energy for chemisorption is not constant and varies with surface coverage. This observation can be expla…
Chromophores with optimized second-order optical nonlinearity to optical loss ratios are synthesized, poled with an electrical field, and coupled into hardened polymer matrixes. Acentric order, which is necessary for electro-optic activity, is optimized by the consideration of chromophore−chromophore electrostatic int…
This article reviews recent developments in multiresolution analysis which make it a powerful tool for the systematic treatment of the multiple length-scales inherent in the electronic structure of matter. Although the article focuses on electronic structure, the advances described are useful for non-linear problems i…