Materials Literature
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Phase behavior and dynamics of liquid−liquid phase separation in binary blends of crystalline polymers, viz., poly(vinylidene fluoride) (PVF 2 ) and poly(butylene adipate) (PBA), have been studied by means of time-resolved light scattering. According to our previous calorimetric study, a single glass transition and tw…
Abstract Dissolution and crystal growth on the (010) cleavage surface of mineral gypsum have been studied by scanning force microscopy, which allows observation of surfaces while they are in contact with aqueous solutions. Etch pits formed on the (010) surface in contact with solutions undersaturated with respect to g…
Using picosecond transient absorption spectroscopy we have examined the dynamics of Cp*Ir(CO) 2 (Cp* = C 5 Me 5 ) in cyclohexane and Cp*Rh(CO) 2 in n -pentane solution at room temperature following 295-nm UV excitation. A transient absorption with an instrument limited risetime was observed for Ir from 440 to 740 nm a…
We model the static and dynamic wetting properties of nonsoluble liquids on surfaces protected by end-grafted molten polymers. We show that in many situations the spreading dynamics should be controlled by viscoelastic phenomena in the polymer films. Temperature changes can cause the spreading velocities to be varied…
The new heteropolyperoxometalate compounds [NMe4][(Me2AsO2){MoO(O2)2}2]1, [NMe4][(Ph2PO2){MoO(O2)2}2]2, [NBun4][(Ph2PO2){WO(O2)2}2]3 and [NH4][(Ph2PO2){MoO(O2)2(H2O)}]4 have been isolated and their crystal structures determined. Compounds 1–3 are dinuclear, whilst compound 4 is mononuclear; in all four structures the…
We report here a comparison of the ability of the monodentate Lewis base n -propylamine and the bidentate molecule ethylenediamine to quench the photoluminescence of light-emitting silicon in three different structural environments. These include porous silicon fabricated from p-type substrates; porous silicon from n-…
New discotic liquid crystals with one, two, or three reactive acrylate end groups were synthesized. They exhibit a wide discotic nematic phase and show spontaneous homeotropic alignment between substrates. The photoinitiated polymerization of these materials was studied. “In-situ photopolymerization” of these disklike…
Cu II - and Zn II -based donor−acceptor porphyrins have been examined for second-order nonlinear optics using the hyper-Rayleigh scattering technique at 1064 nm. Introduction of the metal ions enhances the first hyperpolarizability (β) of the free-base donor−acceptor porphyrins significantly. The open shell Cu II (d 9…
The properties of diluted symmetric A−B diblock copolymers at the interface between A and B homopolymer phases are studied by means of Monte Carlo (MC) simulations of the bond fluctuation model. We calculate segment density profiles as well as orientational properties of segments, of A and B blocks, and of the whole c…
The time dependence of the diffusion process at the interface between two thin films of protonated and deuterated poly(methyl methacrylate) (PMMA) is studied. By neutron reflection, we investigate both the form and the width of the interface between the two polymer layers with subnanometer resolution. At small diffusi…
One-electron reduction of [Pt(bpy) 2 ] 2+ (bpy = 2,2‘-bipyridyl) in aqueous solution results in the formation of black-green lustrous needles on solid electrodes. The crystalline needles grow perpendicularly from the substrate surface and reach lengths of 1−2 cm. Elemental analysis, X-ray photoelectron spectroscopy, a…
We present an experimental study of the effects of hydrophilic, nonadsorbing polymers on the stability of monodisperse oil-in-water emulsions. Above some threshold polymer concentration, the chains induce droplet segregation into fluid and solid phases due to the depletion effect. At higher polymer concentrations, pol…
The factors which affect the adherence of a bacteria cell to the surface of a biomaterial include the surface chemistry of the cell and material, as well as the composition of the adsorbed protein layer when the biomaterial is exposed to circulating blood. In an effort to better understand the mechanisms by which bact…
The motion of a melt-blown fiber was experimentally measured. After exiting the spinning die, a melt-blown fiber was found to vibrate with frequencies and amplitudes that were functions of the operating conditions (polymer flow rate, polymer temperature, air flow rate, and air temperature). Fiber amplitude was measure…
A photochromic saccharide receptor with a diarylethene photoswitch changes the binding event with glucose by photoirradiation.
Racemic poly(3-hydroxybutyric acid) (P(3HB)) was prepared by the ring-opening polymerization of racemic β-butyrolactone (β-BL) in the presence of methylaluminoxane and fractionated into five components with various isotactic diad fractions ([ i ]) varying from 0.88 to 0.54. The degree of X-ray crystallinity of isotact…
Phosphonates are water treatment chemicals that are effectively utilized in many industrial processes as dispersants, bleaching agents, or scale and corrosion inhibitors. In many of these applications, the phosphonates are able to react with divalent cations such as calcium to form stable divalent cation−phosphonate p…
We report the synthesis of continuous and crystallographically aligned single crystals of molybdenum oxide based nanowires up to micrometres in length inside carbon nonotubes: opened tubes are filled using molten MoO3 followed by controlled reduction under dilute hydrogen to MoO2 material.
Two routes for the synthesis of star block copolymers having exactly two arms of polyisoprene (PI) and two of polybutadiene (PB) are described. The first route starts by condensing one molecule of silicon tetrachloride with two of poly(isoprenyl)lithium which has been end-capped by a few units of styrene. The second r…
Cation-exchanged 12-molybdophosphates deposited on a graphite surface were imaged by scanning tunneling microscopy (STM), and their current−voltage behavior in tunneling spectroscopy (TS) measurements was examined. The periodicity of the polyanion arrays in the STM images was ca. 11−14 Å, and the spacing was dependent…