Materials Literature
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The association behavior of a triblock ethylene oxide (E) and butylene oxide (B) copolymer with a very long middle E block (B 12 E 260 B 12 ) in aqueous solution has been investigated by means of laser light scattering. The flower-like closed association behavior of BEB−type triblock copolymers in aqueous solution can…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTTemperature Dependence of Relaxation in Polypropylene and Poly(ethylene-co-propylene)P. G. Santangelo, K. L. Ngai, and C. M. RolandView Author Information Chemistry Division, Code 6120, Naval Research Laboratory, Washington, D.C. 20375-5342Cite this: Macromolecules 1996, 29, 10…
Four block copolymer melts two poly(isoprene- block -dimethylsiloxane) (PI−PDMS) and two poly(ethylene- alt -propylene- block -dimethylsiloxane) (PEP−PDMS) have been investigated through rheological measurements, SANS, and SAXS. In both systems, lamellar to disorder and Ia 3̄ d bicontinuous to disorder transitions hav…
The rate of charge separation in a series of cyclophane-bridged Zn−porphyrin−quinone systems has been investigated in nonpolar and polar solvents by means of fluorescence upconversion. In all systems with driving forces in the range 0.3−1.3 eV, ultrafast charge separation occurs with a rate constant of (2−5) × 10 12 s…
Condensation of a tetraalkyl-α, α-dipyrromethane dialdehyde in a MacDonald-type [2 + 2]-condensation with a trialkyl-α,β-dipyrromethane gives a heptaalkyl N-confused porphyrin.
The one-dimensional arrays {(DMF)10Yb2[Ni(CN)4]3}∞ (1) and {(DMF)10Yb2[Pt(CN)4]3}∞ (2) were prepared from the metathesis reactions of YbCl3 and K2Ni(CN)4 or K2Pt(CN)4 in DMF (DMF = N,N-dimethylformamide). Unlike other one-dimensional structures adopted by complexes of M(CN)42- anions, two unusual array structures were…
Molecular dynamics (MD) simulations for a NiZr model adapted to Hausleitner-Hafner interatomic potentials are analyzed within the mode coupling theory (MCT). Fitting numerical solutions of the (modified) schematic MCT equation with the self-intermediate scattering function of the MD system demonstrates unambiguously t…
Low-temperature MCD spectra were recorded for the bis 4-(dimethylamino)pyridine ( 1 ), bis(1-methylimidazole) ( 2 ), and bis(4-cyanopyridine) ( 3 ) complexes of ferric tetramesitylporphyrinate. The ground state electronic configuration is formally (d xy ) 2 (d xz,d yz ) 3 for both 1 and 2, but these two complexes give…
An evaluation of [3‘-(2-aminoethyl)-2-biphenyl]propionic acid ( 1 ) and 2-amino-3‘-biphenylcarboxylic acid ( 2 ) as β-sheet nucleators was accomplished by incorporating these residues into water soluble peptides. Residue 1 was designed to replace the backbone of the i + 1 and i + 2 residues of a β-turn and reverse the…
Self-assembly of the linear oligobipyridine ligands 3 or 4, of the bipyrimidine 5 and of cooper(I) ions generates the inorganic architectures of ladder type 1 or 2.
Reaction of [Fe(CN)6]3– with [Cu(tpa)(OH2)]2+ produces a bimetallic heptanuclear complex, [Fe{(CN)Cu(tpa)}6]-[ClO4]8·3H2O, which is characterised by single-crystal X-ray diffraction and shown to consist of an iron(II) centre connected by cyano bridges to six copper(II) centres forming spherical units of [Fe{(CN)Cu(tpa…
The pore size distribution of four commercial silica materials saturated with water have been derived from experimental 1 H NMR intensity vs temperature curves ( IT -curves) of the confined water. The observed melting points or transition temperatures of benzene and cyclohexane confined in the same materials are shown…
Carboxylate−alumoxanes, [Al(O) x (OH) y (O 2 CR) z ] n, have been uniformly doped with a transition metal or lanthanide. Thermolysis of the doped alumoxanes yields homogeneous mixed-metal oxides. The carboxylate−alumoxanes were synthesized by the reaction of boehmite, [Al(O)(OH)] n, with either hexanoic, octanoic, met…
A new equilibrium morphology consisting of randomly oriented wormlike micelles dispersed in a continuous matrix is observed in a neat, strongly segregated I 2 S simple graft block copolymer. The equilibrium nature of the worm phase is determined via a set of selective solvent casting and prolonged annealing experiment…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTLiCl Induced Morphological Changes in Polyaniline Base and Their Effect on the Electronic Properties of the Doped FormMarie Angelopoulos, Yun-Hsin Liao, Bruce Furman, and Teresita GrahamView Author Information IBM Research Division,…
A series of regiospecific, alkyl-substituted oligothiophenes were synthesized and their structure/property relationships were studied. The formylation of the oligothiophenes introduced an aldehyde functionality into one of the terminals which can be used to couple with living anionic polystyrene species to generate di…
DnaK, a member of the 70 kDa heat shock protein (hsp70) family, and its complexes with substrate proteins and nucleotides were characterized by small-angle X-ray scattering (SAXS) and size-exclusion chromatography (SEC) techniques. The SAXS data indicated that DnaK has a dumbbell-shaped structure with a maximum dimens…
A time-resolved FT-IR technique combined with an isotopic tracer method has been applied to study CO adsorbates on Cu(+) ions in copper ion-exchanged zeolites. Three kinds of monocarbonyl species were found to adsorb strongly on Cu-zeolite samples after admission and subsequent evacuation of gas phase CO at room tempe…
Supersaturated bicontinuous microemulsions have been used as organized reaction environments for the chemical synthesis of calcium phosphates with interconnected microskeletal architectures. Nucleation of apatite occurs within the nanometer-size water conduits of oil/water microemulsions stabilized with didodecyldimet…
Full optimizations of Pd n cluster geometries have been performed using density functional methods and allowing the occurrence of low-symmetry structures. To account for at least partially for relativistic effects, use was made of Hay and Wadt RECP. The following ground states were found respectively for n = 1, 2, 3,…