Materials Literature
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The film thickness dependence of surface structure for immiscible polystyrene/poly(methyl methacrylate) (PS/PMMA) films was investigated on the basis of atomic force microscopic observation and X-ray photoelectron spectroscopic measurement. In the case of the PS/PMMA film of 25 μm thickness, the air−polymer interfacia…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSemiconductor Surface Reconstruction: The Structural Chemistry of Two-Dimensional Surface CompoundsCharles B. DukeView Author Information Xerox Wilson Center for Research and Technology, 800 Phillips Road 0114-38D, Webster, New York 14580 Cite this: Chem. Rev. 1996, 96, 4, 1…
Ag-coated Au colloidal particles have been prepared by reduction of Ag + in the presence of preformed Au colloids. The composition of the Au 100- x Ag x particles was varied from x = 0 to 80. SERS spectra of pyridine, p -nitroso- N, N‘ -dimethylaniline ( p -NDMA), and trans -1,2-bis(4-pyridyl)ethylene (BPE) have been…
Here we will present a simplification of the form of one popular shape memory alloy (SMA) constitutive model. This simplification allows a more compact written form and hence easier calculations with the one-dimensional SMA constitutive law first developed by Tanaka, later modified by Liang and Rogers, and again by Br…
Using a sol-gel method we have prepared monodispersive particles of La0.67Ca0.33MnO3 in the range from 20 to 110 nm at temperatures from 540 to 1000 °C. A magnetoresistance above 10% was obtained in a field of 1 kOe for all the particles sizes. These results may be relevant for future applications.
We have discovered a superfamily of enzymes related by their ability to catalyze the abstraction of the alpha-proton of a carboxylic acid to form an enolic intermediate. Although each reaction catalyzed by these enzymes is initiated by this common step, their overall reactions (including racemization, beta-elimination…
The effect of finite size on the solidification of o- terphenyl and benzyl alcohol confined in model controlled pore glass (CPG) materials is described. These two organic liquids form either amorphous glasses or crystalline solids in the bulk upon cooling, depending on the rate of cooling and other factors. The solidi…
A monolayer of poly( l -lysine) (PL) is attached covalently via amide bonds to an alkanethiol self-assembled monolayer (SAM) on a gold surface. The amide bond is formed in two steps: the terminal carboxylic acid groups of an 11-mercaptoundecanoic acid (MUA) SAM are first activated to the N -hydroxysulfosuccinimide (NH…
The reduction of Ag + ions in ethanol when certain surfactants are also present in the solution is shown to take place, even in the total absence of light. The reduction process leads to dispersions of silver nanoparticles, which are stable for weeks, although they show a certain tendency to stick to glass walls. Seve…
We describe the preparation of a new set of amphiphilic block copolymers with well-defined molecular weights and block volume fractions. The synthesis of a variety of polyalkane−poly(ethylene oxide) block copolymers was accomplished by a new polymerization−hydrogenation sequence. Initially, anionic polymerization of e…
Low-melting point salts, the basis of industrially relevant ionic liquids, exhibit smectic A mesophases over extended temperature ranges.
The effect of using a realistic model for the electrostatic forces on the calculated structures of molecular crystals is explored by using atomic multipoles derived from an SCF 6-31G** wave function. This was tested on a wide ranging database of 40 rigid organic molecules containing C, H, N, and O atoms, including nuc…
The pyrolysis of four polyhedral oligomeric silsesquioxane (POSS) macromers, Cy 8 Si 8 O 11 (OH) 2, Cy 8 Si 8 O 11 (OSiMe 3 ) 2, Cy 6 Si 6 O 9, and Cy 8 Si 8 O 12 (where Cy = c -C 6 H 11 ) and two POSS−siloxane copolymers [Cy 8 Si 8 O 11 −(OSiMe 2 ) n O−] ( n = 1, oligomer average 5.4) has been studied in argon, nitro…
We examine the equilibrium properties of a starburst dendrimer. A simple Flory theory is developed for the dependence of the radius of gyration of the starburst on its generation. A self-consistent mean field model is solved numerically to verify the Flory theory predictions and elucidate the density profile within th…
The effects of molecular structure on the electronic structure and redox properties of a series of 22 systematically designed conjugated polyquinolines and polyanthrazolines are explored by cyclic voltammetry and spectroelectrochemistry on thin films. The measured electrochemical bandgap of the series of conjugated po…
-position have been prepared as modular components for building block applications. These dyes are stable, accessible, and have suitable spectroscopic features for use as porphyrin accessory pigments in light-harvesting arrays.
The modeling of processes involving multiple length scales is an area of pressing concern, especially in problems such as nanoidentation and crack tip dislocation activity. In these cases, there is more than one characteristic dimension with the nanometer scale arising due to the presence of extended defects such as d…
Conjugated conducting polymers constitute a subject of research lying at the interface between solid-state physics and molecular science. Electronic absorption and vibrational spectroscopies of doped conjugated polymers, whose ground states are nondegenerate, are reviewed from a viewpoint of molecular spectroscopy. Ra…
The experimentally observed asymptotic scaling φ ( L / D ) = constant, for the random packing volume fraction ( φ ) of rods with high aspect ratio ( L / D ), is shown to be the consequence of uncorrelated rod−rod contacts, the constant being equal to 〈 c 〉 = 5.4 ± 0.2 contacts per rod. The weak dependence of 〈 c 〉 on…
A series of bis(2-(3,4-ethylenedioxy)thiophene)-based monomers have been synthesized and fully characterized; specifically ( E )-1,2-bis(2-(3,4-ethylenedioxy)thienyl)vinylene (BEDOT-V), 1,4-bis(2-(3,4-ethylenedioxy)thienyl)benzene (BEDOT-B), 4,4‘-bis(2-(3,4-ethylenedioxy)thienyl)biphenyl (BEDOT-BP), 2,5-bis(2-(3,4-eth…