Materials Literature
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Abstract The impact of preconditioning constituent materials on the morphology development of organically modified montmorillonite–epoxy nanocomposites is examined to determine the sensitivity of exfoliation to material conditions. In situ synchrotron small‐angle X‐ray scattering studies were performed to relate the i…
A continuum model for frictional slip of the yarns of a plain-weave fabric is presented. The model is based on the assumption that the weave is composed of two families of continuously distributed yarns constrained at all times to occupy a common evolving surface in three-dimensional space. The two families may slide…
Abstract We employ atomistic computer modeling to investigate the structure and morphology of poly(ethylene oxide) (PEO) chains confined in 1‐nm slit pores defined by montmorillonite silicate layers. Molecular dynamics computer simulations reveal the Li + cations to be located in the immediate vicinity of the silicate…
Optical absorption and electron paramagnetic resonance (EPR) techniques have been used to characterize the production and thermal decay of point defects in undoped single crystals of KD2PO4 grown at Lawrence Livermore National Laboratory. A crystal was irradiated at 77 K with x rays, and then warmed to room temperatur…
${\mathrm{ZnNMn}}_{3}$ has an unusual cubic-to-cubic structural phase transition near 160 K, which coincides with the onset of the antiferromagnetic (AFM) ordering. The phase transformation involves the formation of microcracks induced by the magnetic moment-dependent lattice expansion, which is also accompanied by an…
The first-principles calculation within density-functional theory is used to search for new candidates of half-metallic ferromagnets in semi-Heusler alloys NiCrM (M = P, As, Sb, S, Se and Te). Our calculations predict that NiCrP, NiCrSe and NiCrTe are half-metallic ferromagnets (HMFs) with magnetic moments of nearly 3…
Controlling the spatial organization of cells is a critical step toward engineering tissues with distributed networks of blood vessels or nerve cells. Here we report a new soft-lithography-based approach for micropatterning proteins and cells on the surface of biodegradable chitosan substrates that are more applicable…
A nanoscale gold thin film and its influence on Ti/SnO 2 -Sb 2 O 5 coating have been investigated by scanning electron microscopy (SEM) and electrochemical methods such as cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and the chronopotentiometric technique in both acidic and caustic solutions. The…
Structures and acid−base properties of La/Al 2 O 3 with different La loadings and calcination temperatures were examined by surface-area measurements, catalyses, IR, XRD, and La K-edge XAFS spectroscopic techniques. Novel concepts for sintering mechanism of γ-Al 2 O 3 and the role of La addition to enhance the thermal…
Abstract Monoalkyl‐ and dialkyl‐imidazolium surfactants were used to prepare organically modified montmorillonites with markedly improved thermal stability in comparison with their alkyl‐ammonium equivalents (the decomposition temperatures increased by ca. 100 °C). Such an increase in the thermal stability affords the…
We calculate the parallel (VV) and (VH) perpendicular polarized Raman spectra of amorphous silica. Model ${\mathrm{SiO}}_{2}$ glasses, uncompressed and compressed, were generated by a combination of classical and ab initio molecular-dynamics simulations and their dynamical matrices were computed within the framework o…
Abstract Poly(ethylene terephthalate) (PET)/montmorillonite (MMT) nanocomposites were prepared by solution intercalation method. The clay was organo‐modified with the intercalation agent cetylpyridinium chloride (CPC). Wide‐angle X‐ray diffraction (XRD) showed that the layers of MMT were intercalated by CPC. Four nano…
We measured the high-temperature thermoelectric properties of single-crystal Ca3Co2O6, which consists of parallel one-dimensional Co2O66− chains separated by Ca2+ ions. The resistivity (ρ) along the c-axis decreases rapidly upon increasing temperature from 2×104 to 8 mΩ cm in a temperature region of 300 to 1073 K. The…
Abstract Poly(ethylene oxide) (PEO)–clay (montmorillonite, hectorite, and laponite) nanocomposites were prepared by a melting intercalation procedure induced by microwave irradiation. The influence of parameters such as the time of irradiation, power, amount and relative ratio of the reagents, and relative humidity wa…
Nanoparticles of nickel have been obtained in solution through reaction of an organometallic precursor, Ni(COD)2 (COD=cycloocta-1,5-diene), with dihydrogen, in the presence of various stabilizing agents. X-ray diffraction studies evidence a face-centered-cubic structure for all samples. Spherical isolated superparamag…
Abstract Coarse‐grained molecular dynamics simulations of stacks of two‐dimensional platelets immersed in a polymer melt were performed to investigate aspects of the polymer matrix that promote the formation of intercalated or exfoliated nanocomposite structures. Such factors include temperature, copolymer architectur…
Bicomponent nanophase-separated poly(2-hydroxyethyl methacrylate)- linked -polyisobutylene (PHEMA- l -PIB) amphiphilic conetworks were synthesized by radical copolymerization of methacrylate−telechelic polyisobutylene (MA−PIB−MA) and different amounts of 2-(trimethylsilyloxy)ethyl methacrylate (SEMA) followed by quant…
We use the 3ω method to study the thermal conductivity of composites of nanoscale alumina particles in polymethylmethacrylate (PMMA) matrices. Effective medium theory and data for the changes in conductivity produced by low volume fractions of particle fillers are used to estimate the thermal conductance G of PMMA/alu…
Abstract Four polyhedral oligomeric silsesquioxane (POSS) cages with vinyl groups were linked to a central siloxane core by hydrosilylation. The goal was to obtain filler particles of sizes between those of the POSS cages themselves and the much larger silica particles typically used to reinforce elastomers. The hydro…
Abstract Polyhedral oligosilsesquioxane (POSS)‐reinforced thermosets based on octaglycidyl epoxy polyhedral oligosilsesquioxane cured with 4,4′‐diaminodiphenyl sulfone (DDS) were prepared and studied for their cure, thermomechanical, and microstructural characteristics. Particular attention was paid to nanometer‐scale…