Materials Literature
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In part I we adapted the recent analytical mean-field theory of polymer adsorption by Semenov et al. to match the numerical lattice theory of Scheutjens and Fleer (SF). Here we calculate explicitly the contributions of trains, loops, and tails to the adsorbance and their size distributions. We choose conditions in the…
Thermal and spectroscopic investigations have been carried out on a number of glasses with a wide range of compositions in the pseudoternary glass system, Li 2 SO 4 −Li 2 O−B 2 O 3, to understand the role of sulfate ions in modifying the borate glass structure. Both nuclear magnetic resonance (NMR) and infrared (IR) s…
The photophysics and photochemistry of all-trans -α,ω-di(2-thienyl)polyenes (with chain length n = 2, 3, 4) and α,ω-di(3-thienyl)polyenes (with n = 3, 4) have been extensively studied by stationary and pulsed spectrometry. Fluorometric and laser flash techniques were used to measure the quantum yields and lifetimes of…
Reactions of hydrogen peroxide with several lacunary polyoxometalates of the 1:11 series, XW 11 O 39 m - (X = Co 3+, Ga 3+, Fe 3+, Si 4+, and P 5+ ), are reported. Synthetic pathways to new polyoxotungstates incorporating dioxygen moieties (peroxo and/or superoxo) are developed. The key step involves treating lacunary…
Selective catalytic reduction (SCR) of NO x by ethylene was investigated on copper and/or cerium ion-exchanged Al−MCM-41 in the presence of excess oxygen. Ce−Al−MCM-41 showed little activity, but Cu−Al−MCM-41 and cerium-promoted Cu−Al−MCM-41 (i.e., Ce−Cu−Al−MCM-41) were found to be active in this reaction. Higher NO x…
We have studied the adsorption and reaction of oxygen and CO on a stepped Pt surface with varying amounts of Au, using temperature-programmed desorption and reaction (TPD and TPR), low-energy electron diffraction (LEED), high-resolution electron energy loss spectroscopy, and steady-state reaction measurements. When th…
Self-assembled octadecyltrichlorosilane (CH 3 (CH 2 ) 17 SiCl 3, OTS) films were deposited on an oxidized silicon wafer. They were carefully exposed to a low-pressure oxygen direct current (dc) plasma and/or Cr vapor. Subsequently, they were characterized by X-ray photoelectron spectroscopy, near-edge X-ray absorption…
We have measured the equilibrium diameter of cylindrical poly(N-isopropylacrylamide) (NIPA) gels with submillimeter diameters under a mechanical constraint along the uniaxial direction. The linear swelling curve, diameter vs temperature, was obtained in the vicinity of the volume phase transition temperature under iso…
An adjacent dibenzotetraazaporphyrin, in which two benzene units are fused to the adjacent pyrrole rings of tetraazaporphyrin skeleton, has been synthesized as a copper complex for the first time and characterized by electronic absorption and magnetic circular dichroism spectroscopy, by cyclic voltammetry and spectroe…
Crystallization kinetics in a homogeneous copolymer of ethene and 1-octene with appended long chain branches has been investigated in real time by means of time-resolved light scattering under H V (cross-polarized) and V V (parallel-polarized) optical alignments using a CCD camera system, simultaneous small angle-X-ra…
The dynamic mean-field density functional method is adapted to describe phase separation in the presence of geometrical constraints. We observe that inclusion of small filler particles (such as rods) already has a dramatic effect on the morphology of polymer melts. The effect is comparable to the effect of applied sim…
In a reaction proceeding within a nanoscopic volume, supramolecular clusters were transformed to polymer objects while retaining their shape and size. Spatial isolation of the cross-linkable blocks of oligobutadiene that were involved in this stitching reaction was achieved by self-assembly of the molecules that made…
Large and reverse hypsochromic and bathochromic shifts on either polaronic (1.29 eV) or bipolaronic (0.68 eV) bands have been determinated from electrochromic polypyrrole films by “in-situ” spectroelectrochemical measurements in the visible region during oxidation/reduction switching. Whatever the rate of the electroc…
We report on the results of extensive Brownian dynamics simulations of colloid phase separation due to depletion flocculation. We study in detail the effect of potential variation at fixed volume fraction of colloid and fixed range of interaction. We find a variety of nonequilibrium behaviors for quenches into the col…
Stickel, Fischer, and Richert [ J. Chem. Phys. 1996, 104, 2043] found the temperature dependence of the α - relaxation time, τ α ( T ), of many small-molecule glass-forming liquids undergoes a change at a characteristic temperature, T B . On the lowering of temperature, τ α ( T ) changes from one Vogel−Fulcher−Tammann…
The adsorption of lysozyme and bovine serum albumin (BSA) onto the surface of a hydrogel polymer has been characterized by neutron reflection and spectroscopic ellipsometry. The polymeric hydrogel was synthesized by copolymerizing methacrylate monomers bearing dodecyl chains and phosphorylcholine (PC) groups. The poly…
A transient metastable rotator phase occurring on crystallization of hexadecane into its triclinic phase from the supercooled melt was directly observed with time-resolved synchrotron x-ray scattering. In this system, the limit of supercooling (the crystallization temperature) is determined by the thermodynamic stabil…
Mesoporous aluminosilicate in the hexagonal phase (MCM-41) has been synthesized from fused fly ash solutions and cationic cetyltrimethylammonium bromide (CTAB) surfactants. We provide direct evidence that an MCM-41 aluminosilicate with a homogeneous chemical composition of Si/Al = 13.4 can be prepared with cationic su…
We examine the effective diffusion coefficient of composites containing randomly placed, impermeable, oriented disks of high aspect ratio. We extend previous work by providing a quantitative framework in which to examine disorder and polydispersity effects, as well as treating explicitly the crossover from the dilute…
A synthetic concept of preparing dense polymer brushes on planar surfaces is described, in which a self-assembled monolayer (SAM) of biphenyllithium moieties on gold substrates is used to initiate anionic polymerization of styrene. The thickness of the resulting dry polystyrene brush, as estimated by ellipsometry and…