Materials Literature
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The first unsymmetrical conjugated dendrimer was synthesized using a rather simple approach that involves only one synthon and two sets of reaction conditions. This dendrimer shows broad absorption in the UV and visible range and possesses an intrinsic energy gradient from the outside branches to the core, naturally s…
Simple thermodynamic arguments are evoked to show that the pressure dependence of the Flory interaction parameter of miscible polymer blends, as derived from small-angle neutron scattering experiments, is directly related to the volume changes on mixing for these systems. This approach is validated by comparison to av…
We report advances for both synthesizing cyclic oligoesters and tailoring their physical properties to make ring-opening polymerization more practical for polyester manufacturing. Solution and suspension methods provide cyclic oligoesters rapidly with high yield and purity. Both methods can be adapted to continuous pr…
FTIR, Raman spectroscopy, and thermogravimetric analysis (TGA) were used to compare the structure and thermal properties of polyoctadecylsiloxane (POS) and octadecyl trichlorosilane (OTS) monolayers. The octadecyl chains in POS had higher conformational and intermolecular order than the same chains of OTS adsorbed as…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTObservation of Local Order in Poly(di-n-alkyl itaconate)sV. Arrighi, A. Triolo, I. J. McEwen, P. Holmes, R. Triolo, and H. AmenitschView Author Information Department of Chemistry, Heriot-Watt University, Edinburgh EH14 4AS, UK; Dip…
Composite polyaniline−silica films produced on glass surfaces during the dispersion polymerization of aniline in the presence of colloidal silica were investigated. The film morphology and composition were characterized by FTIR, UV−vis, and X-ray photoelectron spectroscopies. Compared with pure polyaniline films produ…
Spectacular advances in organometallic chemistry over the past two decades have resulted in single-site catalysts that are revolutionizing production of polyethylene (PE) and isotactic polypropylene (iPP). This report describes an unanticipated benefit of metallocene-catalyzed semicrystalline polyolefins, namely welde…
Single-walled carbon nanotubes (SWNTs) with preferred 2D orientations were synthesized for the first time by chemical vapor deposition (CVD) of methane on silicon surfaces terminated with hydrogen, native oxide, and an ultrathin aluminum layer. The SWNTs grown on Si(100)-based surfaces take two perpendicular direction…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPatterned Hexagonal Arrays of Living Cells in Sol−Gel Silica FilmsShinye Chia, Jun Urano, Fuyuhiko Tamanoi, Bruce Dunn, and Jeffrey I. ZinkView Author Information Department of Chemistry and Biochemistry Department of Microbiology and Molecular Genetics Department of M…
We report the discovery of an orientational transition of bent-core molecules in a background anisotropic medium, in this case a smectic liquid crystal made of rod-like molecules. The resulting director is apolar in nature, and the medium can be described as an orthogonal biaxial smectic. The detailed phase diagram of…
A recently developed self-consistent effective medium approximation, for composites with a columnar microstructure, is applied to such a three-constituent mixture of isotropic normal conductor, perfect insulator, and perfect conductor, where a strong magnetic field {\bf B} is present in the plane perpendicular to the…
The polymer phases of AC60 form distinct crystal structures characterized by the mutual orientations of the (C60-)n chains. We show that the direct electric quadrupole interaction between chains always favors the orthorhombic structure Pmnn with alternating chain orientations. However the specific quadrupolar polariza…
Synthesis of high-flux composite membranes requires methods for deposition of ultrathin, defect-free films on highly permeable supports. Layer-by-layer deposition of polyelectrolytes on porous alumina (0.02 μm pore diameter) produces such membranes. Electron microscopy shows that five bilayers (<25 nm) of poly(allylam…
We describe the design and synthesis of a ferroelectric liquid crystal composed of racemic molecules. The ferroelectric polarization results from spontaneous polar symmetry breaking in a fluid smectic. The ferroelectric phase is also chiral, resulting in the formation of a mixture of macroscopic domains of either hand…
Understanding the dynamic properties of charge carriers at the liquid−semiconductor interface is critical to many applications including photocatalysis, solar energy conversion and photoelectrochemistry. Dynamic properties of charge carriers, including trapping, recombination, and transfer, in a number of semiconducto…
Blocked HI (BHI) was synthesized by the reaction of HI (2-hydroxyethyl methacrylate combined with isophorone diisocyanate) with ϵ-caprolactam (CPL). CPL was used as a blocking agent to improve storage stability of HI. From the Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (1H-NM…
A novel transparent conducting spinel solid solution Cd 1+ x In 2 - 2 x Sn x O 4 (0 ≤ x ≤ 0.75 at 1175 °C) between cubic CdIn 2 O 4 and orthorhombic Cd 2 SnO 4 has been discovered. The extent of this solid solution is noteworthy given that bulk phase relations determined in air over the temperature range 800−1175 °C d…
A detailed mathematical model is developed to describe the dynamics of continuous soluble Ziegler-Natta ethylene polymerizations in reactor trains composed of series of both stirred tank and tubular reactors. The model comprises a detailed description of the reaction mechanism and the mass, energy, and momentum balanc…
The stability of thin film nanocomposites on silicon substrates, formed from mixtures of a symmetric diblock copolymer blended with layered silicate nanocomposites, was investigated using a combination of optical microscopy, atomic force microscopy (AFM), and X-ray diffraction (XRD). Two cases examined are polystyrene…
We report herein a comprehensive study of (porphinato)iron [PFe]-catalyzed isobutane oxidation in which molecular oxygen is utilized as the sole oxidant; these catalytic reactions were carried out and monitored in both autoclave reactors and sapphire NMR tubes. In situ 19F and 13C NMR experiments, coupled with GC anal…