Materials Literature
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Thermoresponsive nanocomposite thin films composed of alternating layers of silica and polymerized N-isopropylacrylamide (NIPAM) or NIPAM plus dodecyl methacrylate (DM) hydrogels were prepared by surfactant-directed evaporation-induced self-assembly (EISA). During EISA, the organic monomers partition within the hydrop…
First-principles molecular dynamics and quantum Monte Carlo techniques are employed to gain insight into the effect of preparation conditions on the structural and optical properties of silicon nanoparticles. Our results demonstrate that (i) kinetically limited nanostructures form different core structures than bulk-d…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTInfluence of Cross-Link Density on the Thermal Properties of Thin Polymer Network FilmsJoseph L. Lenhart and Wen-li WuView Author Information Sandia National Laboratories, P.O. Box 5800, MS 1411, Albuquerque, New Mexico 87185, and Polymers Division, National Institute of Standa…
In order to investigate the relationship between the crystal structure and electronic properties, crystal structure analysis of the organic superconductor $\ensuremath{\alpha}\ensuremath{-}(\mathrm{BEDT}\ensuremath{-}\mathrm{TTF}{)}_{2}{\mathrm{NH}}_{4}\mathrm{Hg}(\mathrm{SCN}{)}_{4},$ where BEDT-TTF is the abbreviati…
Abstract Comprehensive modeling studies were used to describe the kinetics of the solid‐state polymerization (SSP) of poly(ethylene terephthalate). The validity of the model was confirmed by the successful fitting of the experimental results for molecular weight increases, at temperatures ranging from 180 to 230°C and…
Abstract The effect of filler loading on the cure time ( t 90 ) and swelling behaviour of SMR L/ENR 25 and SMR L/SBR blends has been studied. Carbon black (N330), silica (Vulcasil C) and calcium carbonate were used as fillers and the loading range was from 0 to 40 phr. Results show that for SMR L/ENR 25 blends the cur…
We present a method for calculating the inverse of the dielectric matrix in a solid using a band Lanczos algorithm. The method produces a multi-pole approximation for the inverse dielectric matrix with an arbitrary number of poles. We discuss how this approximation can be used to calculate the screened Coulomb interac…
SrF 2 and BaF 2 crystals, doped with the Yb 3+ ions, have been investigated by electron paramagnetic resonance and optical spectroscopy. As-grown crystals of SrF 2 and BaF 2 show the two paramagnetic centres for the cubic (T c ) and trigonal (T 4 ) symmetries of the Yb 3+ ions. Empirical diagrams of the energy levels…
We have used a new method to fabricate photochromic Langmuir–Blodgett (LB) films from a pure azobenzene derivative. The films are used to photoregulate nematic liquid crystals in the host–guest cell (LCD cell). We have demonstrated that the photoresponsiveness of the LCD cell is well determined by phototriggering the…
We present a model for interacting polar-polarizable molecules. Exotic collective effects are recognized as being due to supramolecular interactions: in attractive lattices, bistable behavior is found, and, for proper molecular orientation, multielectron transfer represents the primary photoexcitation event.
Abstract Surface treatment using alkaline solutions was attempted to enhance the surface hydrophilicity and enzymatic hydrolyzability of hydrophobic poly( L ‐lactide) [ie poly( L ‐lactic acid) (PLLA) and poly(ε‐caprolactone) (PCL). The alkaline treatment was performed by immersing the PLLA and PCL films in 0.01 and 4…
The graft of maleic anhydride (MAH) onto isotactic polypropylene (iPP) initiated by dicumyl peroxide (DCP) at 190 °C was studied by means of the Monte Carlo method. The ceiling temperature theory, i.e., no possibility for the homopolymerization of MAH to occur at higher temperatures, was used in this study. The simula…
Rings composed of double-walled carbon nanotubes coherently packed in a triangular arrangement are observed and characterized by transmission electron microscopy (TEM) and electron diffraction. Our conclusions are based on the interpretation of the real space images obtained by TEM and on the analysis of selected area…
Abstract Poly(ethylene terephthalate) (PET), precursors, and solid‐stated samples were evaluated in terms of changing vinyl ester (VE) concentrations. The results obtained through the application of reaction kinetics gave VE contents ranging from 0.7 to 5.5 mmol/kg of PET. As the initial intrinsic viscosity (IV) of th…
Abstract Suspension polymerization in an aqueous medium was applied to the syntheses of styrenic‐based polymerized toner particles. Poly(vinyl alcohol) and benzoyl peroxide were used as a dispersant and an initiator, respectively. The resulting polymerized toners were found to be smooth on their spherical surfaces, an…
Mn(hfac)(2) complexes of [2-(5-pyrimidinyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H- imidazoline-1-oxyl 3-oxide] (1) and its 2-(3-pyridyl) analogue (2) were prepared. Both complexes formed similar dimer structures. However, their packing patterns were considerably different. The pyrimidine dimers were aligned to form a lin…
Abstract Crosslinked amphoteric starches (CASs) with quaternary ammonium cationic and carboxymethyl anionic groups were prepared by a hemidry reaction. Their adsorption behavior for Cr(VI) was investigated, and was found to follow the Langmuir isotherm. The adsorption process was found to be dependent on initial pH, c…
Abstract The solid‐state polymerization (SSP) reaction kinetics of poly(ethylene terephthalate) were investigated in connection with the initial precursor intrinsic viscosity (IV; molecular weight). Evaluations were performed with otherwise equivalent precursors melt‐polymerized to IVs of 0.50, 0.56, and 0.64 dL/g. Th…
We propose a three-dimensional and high-resolution quantitative image analysis technique for the investigation of the internal microstructure of polymer foams. Microscopy, which is the conventional method of investigation of foams, images only the surface of samples, though, three-dimensional x-ray computed microtomog…
The opening of bud -type single-wall carbon nanohorns (SWNHs) by heat treatment in CO 2 was studied by TEM and nitrogen adsorption (77 K). The adsorption isotherms indicate that oxidation by CO 2 at 1273 K provides a sufficient nanohorn opening. The pore structure parameters of the open nanohorns can be controlled by…