Materials Literature
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Polycarboxylic acids are well-known to affect calcium carbonate crystallization. Agarwal et al. ( Ind. Eng. Chem. Res. 2003, in press) reported previously the synthesis of polymaleimide by a variety of techniques and initiators. In the present work, the effect of these polymers on calcium carbonate crystallization was…
The low flammability of poly(3,3‘-dihydroxybiphenylisophthalamide) (PHA) and its halogen, methoxy, phosphinate, or phosphate derivatives was characterized by multiple analytical techniques, emphasizing the thermal decomposition behavior is the basis for the polymer flammability. Pyrolysis gases from these polymers wer…
A generalized Landau-Ginzburg model is constructed and used to develop a methodology for analyzing graded ferroic materials. Material system inhomogeneities are assumed to arise from compositional, temperature, or stress gradients. These spatial nonuniformities are shown to give rise to local order parameters having c…
Abstract Biodegradable poly( l ‐lactide) (PLLA) and poly(ε‐caprolactone) (PCL) were electrospun into ultrafine fibers. The technological parameters influencing the spinning process and morphology of the fibers obtained were examined. These parameters included solvent composition, addition of certain organic salts, mol…
Hybrid compounds with two functional centers consisting of a metallosalen moiety (M[bond]salen; M = Mn, Co, Ni, and Pd) connected by an alkylene bridging group to a lacunary Keggin type polyoxometalate were synthesized and characterized. In these metallosalen-polyoxometalate compounds (M[bond]salen[bond]POM) it was sh…
This paper describes the synthesis and supramolecular organization of two novel hybrid diblock copolymers based on poly(ethylene glycol) (PEG) and peptide sequences inspired by the coiled coil protein folding motif. The self-organization of the diblock copolymers is driven by the tendency of the peptide segments to fo…
This article reviews the progress of atomic force microscopy (AFM) in ultra-high vacuum, starting with its invention and covering most of the recent developments. Today, dynamic force microscopy allows to image surfaces of conductors \emph{and} insulators in vacuum with atomic resolution. The mostly used technique for…
The structure of single atoms in real space is investigated by scanning tunneling microscopy. Very high resolution is possible by a dramatic reduction of the tip-sample distance. The instabilities which are normally encountered when using small tip-sample distances are avoided by oscillating the tip of the scanning tu…
The role that occupied $d$ bands play in the inelastic lifetime of bulk and surface states in Ag is investigated from the knowledge of the quasiparticle self-energy. In the case of bulk electrons, $sp$ bands are taken to be free-electron like. For surface states, the surface band structure of $sp$ states is described…
Five different ordered mesoporous silica samples displaying various pore sizes and structures (two small-pore MCM-41, two large-pore MCM-41, and one small-pore MCM-48) and one amorphous silica gel have been grafted with either aminopropyl or mercaptopropyl groups. The resulting aminopropyl-grafted silicas (APS) and me…
A new type of one-dimensional (1D) carbon structure, carbon nanowires (CNWs), was discovered in the cathode deposits prepared by hydrogen arc discharge evaporation of carbon rods. Observation of high-resolution transmission electron microscopy (HRTEM) indicates that a CNW consists of a multiwalled carbon nanotube (MWN…
Abstract A vinyl‐functionalized polyphosphate (PIOP) was synthesized by ring‐opening polymerization of 2‐isopropyl‐2‐oxo‐1,3,2‐dioxaphospholane and 2‐(2‐oxo‐1,3,2‐dioxaphosphoroyloxyethyl methacrylate) with triisobutylaluminum as an initiator. The number‐averaged molecular weight of the PIOP was 1.2 × 10 4 . The avera…
The bonding energetics in a variety of alkaline metal, alkoxides and phenoxides, MOR, was investigated based on the corresponding enthalpies of formation in the crystalline state determined by reaction-solution calorimetry. The results obtained at 298.15 K were as follows: Delta(f)H(m)(o)(MOR, cr)/kJ mol(-1) = 382.7+/…
Abstract A series of fluorinated poly(amide imide)s were prepared from 1,4‐bis(2′‐trifluoromethyl‐4′‐trimellitimidophenoxy)benzene and various aromatic diamines [3,3′,5,5′‐tetramethyl‐4,4′‐diaminediphenylmethane, α,α‐bis(4‐amino‐3,5‐dimethyl phenyl)‐3′‐trifluoromethylphenylmethane, 1,4‐bis(4′‐amino‐2′‐trifluoromethylp…
We demonstrate experimentally the technique of fabricating large diffractive optical elements (DOEs) in thick film on a concave lens surface (mirrors) with precise alignment by using the strategy of double exposure. We adopt the method of double exposure to overcome the difficulty of processing thick photoresist on a…
Abstract Thermally unstable polymers such as poly(methyl methacrylate) are degraded considerably during industrial processing. This degradation and its reduction to a minimum have been investigated in both lab and continuous pilot‐scale experiments. A three‐step degradation mechanism, starting at 180 °C, was proved by…
The reactions of neutral or cationic manganese carbonyl species towards the oxo-nitrosyl complex [Na(MeOH)[Mo(5)O(13)(OCH(3))(4)(NO)]](2-) have been investigated in various conditions. This system provides an unique opportunity for probing the basic reactions involved in the preparation of solid oxide-supported hetero…
In order to clarify the mechanism of the photoluminescence (PL) from amorphous silicon quantum dots $(a$-Si QDs), we calculate, in the tight-binding scheme, the emission spectra and the radiative recombination rate $\mathcal{P}$ of the direct band-to-band recombination process. For a-Si QDs smaller than 2.4 nm in diam…
The microstructure and dynamics of a colloidal system interacting via short-ranged interparticle potential is studied by ultra-small-angle x-ray scattering and x-ray photon correlation spectroscopy. A colloidal gas-liquid type transition is induced when the short-ranged attractive interactions attain sufficient magnit…
Abstract Nitrile rubber (NBR), poly(acrylonitrile‐ co ‐butadiene) or NBR packers, are used to seal oil‐well tubing, where they often come into contact with ZnBr 2 brines at high temperatures and pressures. Under these conditions, NBR exhibits accelerated chemical degradation, which results in embrittlement and crackin…