Materials Literature
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Lower oxidation potentials than for the monomeric starting materials are displayed by the diporphyrins obtained by one-electron oxidation with tris(4-bromophenyl)ammonium hexachloroantimonate [see, for example, Eq. (1)]. This and the strong red shift observed for the Soret bands of the product are indicative of extens…
We obtain the many-body hydrodynamic friction and mobility matrices describing the motion in a fluid of N hard-spheres with stick boundary conditions in the presence of a planar hard wall or free surface using (1) a multipole expansion of the hydrodynamic force densities induced on the spheres and (2) an image represe…
A new preparation is reported which, for the first time, results in a thin, crystalline SiO 2 film on a Mo(112) single crystal. The procedure consists of repeated cycles of silicon deposition and subsequent oxidation, followed by a final annealing procedure. AES and XPS have been used to control film stoichiometry. LE…
A poly(1,5‐diaminoanthraquinone) [poly(DAAQ)], which is a conducting polymer condensed with 1,4‐benzoquinone, was studied electrochemically and was proposed as a new category of electrochemical capacitor material. In common nonaqueous media, the poly(DAAQ) showed two sets of reproducible redox couples for repeated cyc…
Polyoxotungstates with propyl methacrylate functionalities and ethyl methacrylate were copolymerized in acetonitrile leading to the formation of networks whose swelling properties have been studied in several organic solvents. The polyanions ensure the cross-linking of poly(ethyl methacrylate) chains and are therefore…
Micro-Raman scattering from single-crystal diamond was performed over the temperature range 77--873 K. These measurements show that the Raman phonon frequency and the linewidth are temperature dependent, the linewidth and the frequency extrapolated to 0 K are $1.103\ifmmode\pm\else\textpm\fi{}0.03{\mathrm{cm}}^{\mathr…
We develop a computer simulation for the dynamic behavior of a phase-separating binary mixture that contains mobile, solid particles. The system models “filled polymers”, which contain not only a blend of different macromolecules, but also solid fillers. We focus on the case where one of the components preferentially…
We present the technique of bideposition to realize thin-film helicoidal bianisotropic mediums (TFHBM's) that exhibit high optical activity. We show, by experiment as well as by simulation, that the optical rotation produced by these chiral sculptured thin films is roughly proportional to the square of the local linea…
The crystal structure of La1−xSrxCoO3−δ in the composition range 0≤x≤0.8 was investigated by means of powder XRD. A more detailed study was performed on the x=0.7 composition by neutron diffraction, HRTEM, SAED, image analysis and PEELS. The XRD results indicate a long-range cubic perovskite symmetry (spacegroup Pm3̄m…
Abstract High pressures and temperatures generated during the cavitation process are now considered responsible for the observed physical and chemical transformations using ultrasound irradiation. Effects of various operating parameters reported here include the frequency, the intensity of ultrasound, and the initial…
A complete mechanistic study of the solution dynamics of [Eu(DOTAM)(H 2 O)] 3+ is performed through 1 H and 17 O NMR variable pressure and temperature studies. An unambiguous understanding of the water exchange was possible thanks to the first 17 O NMR observation of the bound water signal on both the M- and m-isomers…
An important new class of materials for optical device applications—polymer-dispersed liquid crystals (PDLCs)—is reviewed. The author gives an overview of these materials along with a description of their fabrication, fundamentally important properties, and current as well as possible future applications. The Figure i…
Metal complexes of pyridine and bipyridine-type ligands represent an important class of nonlinear optical (NLO) materials: (i) They can incorporate a variety of functionalised ligands with a wide range of metals which can give rise to tuneable NLO properties; (ii) they are generally associated with intense low-lying c…
Nanotubes are rich in potential applications, but they are very difficult to purify, and yields are often less than 1 %. The solution presented here is to suspend nanotubes in a polymer matrix, which then acts as a filtration system. Incorporation is achieved by sonication, followed by a period of settling, during whi…
Two potential obstacles to the creation of implantable tissue engineered heart valves are inadequate mechanical properties (ability to withstand hemodynamic stresses) and adverse host-tissue reactions due to the presence of residual nondegraded polymer scaffold. In an attempt to address these problems, we developed an…
The rheological effects occuring when an emulsion is mixed with a suspension can be detected using a helical ribbon stirrer. The stirrer rotates in a rheometer cup and is connected to the torque sensor of the rheometer. During mixing, microstructural changes which are related to the interactions between the continuous…
Mixing is the most important operation in polymer processing. Uniformity of the molecular weight, degree of entanglement, temperature, and composition, is the prerequisite for good performance. Mixing of molten polymers is always within the laminar (as opposed to turbulent) flow regime. This paper presents an overview…
In this paper, we study gap effects and apparent slip phenomena in a torsional flow of a moderately concentrated hydrophobically modified associative polymer solution.Slip is investigated by varying the gap between concentric parallel disks, and the plate surface roughness.The onset of apparent slip is shown to occur…