Materials Literature
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Abstract This investigation deals with the thermal or thermooxidative degradation behavior of three engineering polymers [e.g., poly(ethylene terephthalate) (PET), poly(ether sulfone) (PES), and poly(ether ether ketone) (PEEK)] by using thermogravimetry‐coupled mass spectrometry (TG‐MS) analysis. The experiments were…
The use of aqueous emulsions as the media when conducting cross-coupling reactions, instead of homogeneous solutions, produces covalently cross-linked conjugated polymer particles (see picture). The size of the spherical particles can easily be tuned over a wide range (mm to nm) by modification of the reaction conditi…
Abstract Grafted inorganic nanoparticles can greatly improve the mechanical performance of polymers. To examine the effects of the interfacial characteristics generated by the grafting polymer bonded to nanoparticle surfaces, we chemically grafted nano‐silica with different polymers and then melt‐mixed it with polypro…
The alignment of thin films of symmetric diblock copolymer of polystyrene and poly(methyl methacrylate), PS- b -PMMA, in an electric field was studied as a function of film thickness and interfacial energy using small-angle neutron scattering and transmission electron microscopy. There is a competition between the app…
The first theoretical evidence for tetracoordinate planar nonmetals hosted at the centers of square hydrometal complexes M4H4X (M=Cu, Ni; X=B, C, N, O; see picture) has been obtained by ab initio calculations. These predictions may open a new branch of chemistry of nonmetal-centered hydrometals with potential applicat…
Shell shock: Shell cross-linked (SCL) micelles (3) are prepared by polyelectrolyte complexation by using a micelle-forming cationic ABC triblock copolymer (1) in conjunction with an anionic diblock copolymer cross-linker (2). This ionic cross-linking approach involves polymeric reagents that form physical complexes ra…
The Ge/sub 2/Sb/sub 2/Te/sub 5/ (GST) thin film is well known to play a critical role in PRAM (Phase Change Random Access Memory). Through device simulation, we found that high-resistive GST is indispensable to minimize the writing current of PRAM. For the first time, we tried to increase the GST resistivity by doping…
We report the first observation of oscillations of the electromagnetic field in an optical superlattice based on porous silicon. These oscillations are an optical equivalent of well-known electronic Bloch oscillations in crystals. Elementary cells of our structure are composed by microcavities whose coupling gives ris…
Previous theoretical investigations of colossal magnetoresistance (CMR) materials explain this effect using a "clustered" state with preformed ferromagnetic islands that rapidly align their moments with increasing external magnetic fields. While qualitatively successful, explicit calculations indicate drastically diff…
Using a novel approach to calculate optical properties of strongly correlated systems, we address the old question of the physical origin of the alpha to gamma transition in Ce. We find that the Kondo collapse model describes the optical data better than the Mott transition picture. Our results compare well with exist…
Extensive electronic structure calculations are performed to obtain the stable geometries of metals like Al, Ga and In on the Si(001) surface at 0.5 ML and 1 ML coverages. Our results coupled with previous theoretical findings explain the recent experimental data in a comprehensive fashion. At low coverages, as shown…
We report a uniaxial pressure-dependence of magnetism in layered perovskite strontium ruthenate Sr3Ru2O7. By applying a relatively small uniaxial pressure, greater than 0.1 GPa normal to the RuO2 layer, ferromagnetic ordering manifests below 80 K from the enhanced-paramagnet. Magnetization at 1 kOe and 2 K becomes 100…
The volume of tantalum versus pressure has been accurately measured up to 101 GPa by single-crystal x-ray diffraction, with helium as pressure transmitting medium. Slight deviation from previous static determinations is observed. Discrepancy with reduced shock-wave and ultrasonic data supports recent doubts about the…
Using effective-field theory with correlations, we investigate the effects of interfacial pseudo-spin coupling fluctuations on the susceptibility and polarization of ferroelectric superlattices within the framework of transverse Ising model. It is found that the interfacial coupling fluctuations increase the susceptib…
Abstract The aim of this work was to study the variations in the oxygen diffusion, solubility, and permeability coefficients of polylactide (PLA) films at different temperatures (5, 23, and 40°C) and water activities (0–0.9). The results were compared with the oxygen diffusion, solubility, and permeability coefficient…
Carbon nanotubes are being contemplated as reinforcements for the next generation of composite materials. Stress and strain measures at an atomic scale are required to study the effect of inhomogeneities in nanotube based structures. In this work, we have adapted three different stress measures at atomic scales and in…
A comparison of the stability and catalytic activity of PAMAM−OH generation 4 dendrimer−Pd nanoparticles (1.3 ± 0.1 nm) with the previously studied PVP−Pd nanoparticles (2.1 ± 0.1 nm) in the Suzuki coupling reaction between phenylboronic acid and iodobenzene is conducted. After the first cycle, the average size of the…
Completing RGB color space: The electrochemical and optical properties of the first electrochemically prepared conducting polymer that is green in its neutral form are reported. The extreme stability of this polymer after 10 000 double potential steps makes it the best and only candidate for providing the missing thir…
We present classical molecular dynamics simulations demonstrating that single-wall carbon nanotube (SWNT) bundles collapse under hydrostatic pressure. The collapse pressures obtained as a function of nanotube diameter are in excellent quantitative agreement with new data presented here for small diameter (d approximat…
The wetting of porous templates with polymer melts and solutions or polymer-containing mixtures is a simple and versatile method for the preparation of tubular structures with diameters ranging from a few tens of nanometers to micrometers. The tube walls can be made of a multitude of materials, some of which have thus…