Materials Literature
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Abstract The improvement of oxygen‐barrier properties of glassy polyesters by orientation was examined. Poly(ethylene terephthalate) (PET), poly(ethylene naphthalate), and a copolymer based on PET in which 55 mol % of the terephthalate was replaced with bibenzoate (PET‐BB55) were oriented by constrained uniaxial stret…
Abstract The synthesis and characterization of novel polymerized high internal‐phase emulsions (polyHIPE) materials are described. Homogeneous, highly porous, low‐density, open‐cell crosslinked copolymers were prepared by polymerizing the continuous phase of HIPE containing styrene and varying amounts of 2‐ethylhexyl…
We propose a simple model of charge transport that predicts the conducting properties of disordered materials. The transport of charge is assumed to occur by trapping and detrapping of electrons in localized states and diffusion via a conduction-band level. The input is an arbitrary density of localized states (DOLS)…
Abstract The crystallinity of isotactic polypropylene (iPP), when deformed with plastic plane‐strain compression, was studied with wide‐angle X‐ray scattering (WAXS) and differential scanning calorimetry (DSC) techniques. A comparison of the obtained crystallinity data with annealed iPP samples was performed. The mate…
Apolar organic suspensions of rodlike cellulose whiskers modified by a surfactant are investigated by small angle neutron scattering. Guinier and Porod analyses are performed to characterize the increase of cross-sectional radius of gyration observed between organic and aqueous suspensions of whiskers. In addition, a…
We initiate the development of a theory of the elasticity of nanoscale objects based upon new physical concepts which remain properly defined on the nanoscale. This theory provides a powerful way of understanding nanoscale elasticity in terms of local group contributions and gives insight into the breakdown of standar…
The electronic structure of the $(2\sqrt{2}\times\sqrt{2})R45^{\circ}$ O/Cu(001) system has been calculated using locally self-consistent, real space multiple scattering technique based on first principles. Oxygen atoms are found to perturb differentially the long-range Madelung potentials, and hence the local electro…
The optical properties of point defects in as-grown natural silica are reviewed. Two emissions peaked at 4.2 eV ($α_E$ band) and at 3.1 eV ($β$ band), related to an absorption band at 5.1 eV ($B_{2β}$), have been experimentally investigated on the basis of their temperature dependence and their kinetic decay. Our resu…
Nanocomposites were prepared from waxy maize starch plasticized with sorbitol as the matrix and a stable aqueous suspension of tunicin whiskers-an animal cellulose-as the reinforcing phase. The composites were conditioned at different relative humidity levels. The conditioned films were characterized using scanning el…
We studied various gas molecules (NO 2 , O 2 , NH 3 , N 2 , CO 2 , CH 4 , H 2 O, H 2 , Ar) on single-walled carbon nanotubes (SWNTs) and bundles using first principles methods. The equilibrium position, adsorption energy, charge transfer, and electronic band structures are obtained for different kinds of SWNTs. Most m…
Abstract The effects of ultrasonic irradiation on crystallization behavior of polypropylene (PP)‐loaded fillers with nucleating activities, such as sodium benzoate, talc (P), talc (A), and mica, are examined. DSC and WAXD analyses demonstrate that the crystalline structure of PP is changed through ultrasonic vibration…
The isolation and identification of the first examples of anhydrous lanthanide chloride tetraphenylporphyrin complexes have been described. The purple complexes were generated by the reaction of dilithiotetraphenylporphyrin bis(dimethoxyethane) with lanthanide trichloride tris(tetrahydrofuran) salts to yield the produ…
High-throughput methods are utilized in the discovery and optimization of heterogeneous catalyst formulations that promote single-walled carbon nanotube (SWNT) synthesis. Catalyst compositions, substrates, and reaction conditions are varied to efficiently investigate SWNT growth by chemical vapor deposition (CVD). A r…
Raman scattering studies as functions of temperature, magnetic field, and Gd substitution are used to investigate the evolution of magnetic polarons and spin-carrier interactions through the metal-insulator transition in Eu(1-x)Gd(x)O. These studies reveal a spin-fluctuation-dominated paramagnetic (PM) regime for T>T*…
The pi-radical cation and anion of the dizinc complex of a bis(triarylporphyrinyl)butadiyne, 1+ and 1-, respectively, display remarkably similar near-IR signatures, with intense bands near 1000 and 2500 nm, as predicted by the appropriate frontier-orbital model for inter-porphyrin coupling across the conjugated bridge.
The equilibrium structure of ${\mathrm{ErO}}_{n}$ $(n<~6)$ complexes in crystalline silicon has been investigated by density-functional computations. Two different geometries have been considered, corresponding to the substitutional and tetrahedral interstitial site for erbium. All atomic coordinates have been opti…
Five-coordinate iron(III) 2,7,12,17-tetrapropylporphycene (TPrPc)Fe(III)X (X = C(6)H(5)O(-), Cl(-), Br(-), I(-), ClO(4)(-)) complexes have been investigated. The (1)H NMR spectra demonstrate downfield shifts for pyrrole resonances [(TPrPc)Fe(III)(C(6)H(5)O), 65.3 ppm; (TPrPc)Fe(III)Cl, 28.5 ppm] but large upfield ones…
The structural evolution taking place during CTAB/TEOS based solvent evaporation-induced thin film formation has been followed by in-situ time-resolved SAXS; this shows that the final Pm3n cubic structure is formed via the formation of lamellar and hexagonal intermediate structures within the water rich evaporation re…
Abstract The ring‐opening polymerization of a monomer containing a free carboxylic acid group is reported for the first time. The monomer, 5‐methyl‐5‐carboxyl‐1,3‐dioxan‐2‐one (MCC), was copolymerized with trimethylene carbonate (TMC) in an enzymatic ring‐opening polymerization conducted in bulk at 80 °C. The low‐melt…
The structure and electronic properties of a series of Mn IV spinel oxides, with the general formula, AM 0.5 Mn 1.5 O 4 (A = Li, Cu; M = Ni, Mg), are investigated. These materials form an interesting analogy to pyrochlore structures that show colossal magnetoresistance properties. Studies of all the compounds show spo…