Materials Literature
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Extension of the π-system of 1,6,7,12-tetrakis(aryloxy)-3,4,9,10-perylenetetracarboxdiimide was achieved by the condensation of 1,6,7,12-tetrakis(aryloxy)-3,4,9,10-perylenetetracarboxylic bisanhydride with 1,2-diaminobenzene, 1,8-diaminonaphthalene, and 9,10-diaminophenanthrene. A full characterization of the resultin…
The true stress−strain characterization of the tensile yield as a function of temperature and cross-head speed is reported for three ethylene−butene copolymers having different crystal weight fractions in the range 0.66−0.35. Evidence is given of two plastic processes operating competitively depending on the experimen…
The demand for actuators featuring biomimetic properties, such as linearity, high power density and compliance, is growing in microrobotics and bioengineering. In the present paper a novel linear actuator is presented. It exploits the electromechanochemical phenomena of -electron conjugated conducting polymers, occuri…
Electron spin resonance (ESR) experiments in the paramagnetic phase of ${\mathrm{R}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{B}}_{\mathrm{x}}$${\mathrm{MnO}}_{3+\mathrm{\ensuremath{\delta}}}$n(R=La,Pr; B=Ca,Sr) show, for 1.1 ${\mathrm{T}}_{\mathrm{C}}$\ensuremath{\lesssim}T\ensuremath{\lesssim}${2\mathrm{T}}_{\…
The preparation and crystal structures of the n = 2 Ruddlesden−Popper phases Sr 2 - x Ln 1+ x Mn 2 O 7 (0 ≤ x ≤ 0.5, Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, and Er) are described. The crystal chemistry and stability of this structure is governed by the size of the lanthanide cation. Partial ordering of the Sr 2+ a…
Abstract Numerous examples in the literature illustrate how the coextrusion of film with three or more polymeric layers is economically used to achieve a desirable mix of end‐use characteristics. More recently, layer‐multiplying devices permit two polymers of widely dissimilar solid‐state properties to be combined int…
A new type of disc-shaped molecule (1 a-c) has been synthesised and characterised. The molecules were built up by linking three lipophilic, N-monoacylated 2,2'-bipyridine-3,3'-diamine wedges to a central 1,3,5-benzenetricarbonyl unit. They show liquid crystalline behaviour, as shown by DSC, polarisation microscopy and…
Other| February 01, 1997 Structural behavior, crystal chemistry, and phase transitions in substituted leucite: High-resolution neutron powder diffraction studies David C. Palmer; David C. Palmer University of Cambridge, Department of Earth Sciences, Cambridge, United Kingdom Search for other works by this author on: G…
Nearly monodisperse CdSe nanoclusters, surface-passivated with a layer of trioctylphosphine and trioctylphosphine oxide, have been sequestered within phosphine-containing domains in a diblock copolymer. A convergent approach to fabrication of these composites was adopted via independent synthesis of nanoclusters and p…
Abstract Rehydration is shown to be straightforward for the reconstruction of polyoxometallate-pillared layered double hydroxides. Zn-Al hydrotalcite-like minerals were prepared with Zn/Al ratios of 1 to 5 by coprecipitation at pH 7. Good crystallinity was obtained for samples with Zn/Al ratios above 2. Thermal decomp…
A straightforward and very efficient pathway has been reported for the synthesis of a functional derivative of ε-caprolactone, i.e. 5-ethylene ketal ε-caprolactone. This new monomer has been homopolymerized and copolymerized with ε-caprolactone in a well-controlled manner, strongly suggesting absence of any side react…
Two tetracarboxylic dianhydrides with a polyalicyclic structure, bicyclo[2.2.2]octane-2- endo,3- endo,5- exo,6- exo -tetracarboxylic 2,3:5,6-dianhydride ( 5a ) and bicyclo[2.2.2]octane-2- exo,3- exo,5- exo,6- exo -tetracarboxylic 2,3:5,6-dianhydride ( 5b ), were synthesized, and polycondensations of the dianhydrides w…
The photophysical properties and their temperature dependence are reported for the sterically encumbered nonplanar zinc and free base 2,3,5,7,8,10,12,13,15,17,18,20-dodecaphenylporphyrins (ZnDPP and H 2 DPP), and 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrins (ZnOETPP and H 2 OETPP), and the zinc compl…
A series of mixed-ligand transition-metal diimine dithiolate complexes have been prepared, and their nonlinear optical properties have been investigated. Molecular hyperpolarizabilities have been obtained from electric field induced second harmonic generation experiments at 1.9 μm and range in magnitude from 0 to −39…
An attractive way of making polymer-dispersed liquid-crystal (PDLC) films is through photopolymerization-induced phase separation. The electro-optic properties of these films are determined in large part by the size, shape, and packing of the embedded liquid-crystal drops. We explore the relationships between the cond…
The combination of turnover rate measurements and surface science techniques allows a firm quantification of rates in heterogeneous catalysis by metals. There are many examples of reactions where the turnover rates from different laboratories are the same. However, there are still problems, as in the isomerization and…
We report the design and performance of 300-mK composite bolometers that use micromesh absorbers and support structures patterned from thin films of low-stress silicon nitride. The small geometrical filling factor of the micromesh absorber provides 20x reduction in heat capacity and cosmic ray cross section relative t…
The relationship between surface sediment diatom (Division: Bacillariophyta) assemblages and measured water chemical and environmental variables in 30 lakes from northern Fennoscandia were examined...
Hybrid molecular electrodes , based on a conducting polymer matrix containing a dispersion of an electroactive inorganic component, are reported. The phosphomolydate anion, [PMo 12 O 40 ] 3⊖ , is dispersed in polypyrrole to investigate cooperative phenomena between the components. The interactions are shown to influen…
Modulation of light by light as stimulus has been explored by the use of liquid-crystalline (LC) materials with photosensitive moieties. Azobenzene derivatives with monomeric and polymeric forms were prepared, which show nematic (N) LC behavior in the trans form and no LC phase in the cis isomer. Photoirradiation of a…