Materials Literature
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In contrast to other types of segmented multiblock thermoplastic elastomers, simple ABA block copolymers represent a class of well-defined nanostructured materials. Due to the inherent block lengths built in during the polymerization, the microdomain structure of block copolymers exhibits a size scale of typically 10−…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTA Low-Temperature Solution Phase Route for the Synthesis of Silicon NanoclustersRichard A. Bley and Susan M. KauzlarichView Author Information Department of Chemistry University of California Davis, California 95616 Cite this: J. Am. Chem. Soc. 1996, 118, 49, 12461–124…
The structure of the phases obtained upon dehydration and decomposition of hydrotalcite-like compounds is investigated by several experimental techniques. A reaction mechanism is proposed encompassing a change in coordination of the M(III) cations during the dehydration step. The formation of a 3-dimensional structure…
LaMnO3 films doped with Ca, Ba, or Sr have been fabricated using the metalorganic decomposition technique. These films exhibit paramagnetic-to-ferromagnetic phase transitions at 250, 300, and 350 K, respectively. By measuring the film magnetization as a function of field and temperature we have determined the entropy…
Raman spectra of neutral and electrochemically doped regioregular poly(3-decylthiophene) were studied using different excitation lines, namely, 457.9, 514.5, 676, and 1064 nm. Contrary to the case of nonregioregular poly(3-decylthiophene) obtained by polymerization with FeCl 3, in regioregular polymer the position of…
The steam invigoration of pitches (softening points 85 and 280 °C) homogenized with 1−3 wt % of organo rare-earth metal complexes such as Ln(C 5 H 5 ) 3 or Ln(acac) (Ln = Y, Yb) at 930 °C provided activated carbons with an extremely high mesopore ratio, >70%. The resulted activated carbon selectively adsorbs giant mol…
Polylactide (PLA) stereocopolymers with ( l ) repeat unit contents of 75%, 80%, 82%, 85%, 90%, 91%, 92%, 94%, and 95% were prepared from mixtures of ( l )-/( d )-lactide and ( l )-/ meso -lactide. Compression molding of these products gave amorphous films which, for ( l ) contents ≥90%, were also annealed above T g to…
Model heterogeneous surfaces consisting of alternating and parallel 2.55 μm hydrophobic and 2.45 μm hydrophilic strips were prepared on a gold film by patterning self-assembled monolayers of hexadecanethiol and mercaptohexadecanoic acid using an elastomer stamp. The advancing and receding contact angles were measured…
The LCuGd(NO3)3·Me2CO complex crystallizes in the monoclinic space group P21/c (No. 14) in a cell having the dimensions a = 9.799(1) Å, b = 18.926(3) Å, c = 16.012(1) Å, β = 96.530(8)°, Z = 4. The four units forming the unit cell do not display any obvious short contacts between them. The magnetic behavior is characte…
A model of the cubic mesoporous silicate MCM-48, based on the gyroid minimal surface, has been generated by computer simulation. Transmission electron micrographs and X-ray diffraction (XRD) patterns have been recorded for MCM-48 and compared with the images and XRD patterns obtained by modeling. The gyroid minimal su…
Two ceria samples with differing specific surface areas and porosities have been investigated by IR spectroscopy. A ν(OH) band at ca. 3510 cm–1 was found to be due to cerium oxyhydroxide impurities within the ceria pores. One-, two- and three-coordinated OH species were observed. Doubly bridging OH species in the vici…
A series of triblock PLA/PEO/PLA copolymers were synthesized by polymerization of l -lactide in the presence of PEG2000, a bifunctional OH-terminated poly(ethylene glycol) ( M̄ n = 1800) using Zn metal or CaH 2 as catalyst. The resulting copolymers were analyzed by various techniques including 1 H and 13 C nuclear mag…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTEntanglements at Polymer Surfaces and InterfacesHugh R. Brown and Thomas P. RussellView Author Information Almaden Research Center, IBM Research Division, 650 Harry Road, San Jose, California 95120Cite this: Macromolecules 1996, 29,…
The structure of hydroxylated alumina surface is analysed by IR spectroscopy. The variety of OH groups differing in number and coordination of surrounding metal atoms, for the completely hydrated surface, either formed by ideal low-index planes, or complicated by crystal edges and corners or cation vacancies, is restr…
Peptide-amphiphiles with collagen-model head groups and dialkyl chain tails have been synthesized and shown to self-assemble into highly ordered polyPro II like triple-helical structures when dissolved in aqueous subphases. Evidence for this self-assembly process has been obtained from (a) compression of stable peptid…
The local structure of dragline silk from the spider Nephila madagascariensis is investigated by solid-state nuclear magnetic resonance. Two-dimensional (2D) spin-diffusion experiments show that the alanine-rich domains of the protein form β-sheet structures in agreement with one-dimensional NMR results from a differe…
Aqueous acetone extracts of shoots of Eurasian watermilfoil (Myriophyllum spicatum) exhibit a strong inhibitory action against various coccoid and filamentous cyanobacteria and to a slightly less extent against chlorophytes and diatoms. Bioassay-directed fractionation led to the isolation of a hydrolysable polyphenol,…
The hydroxylation of proline residues in collagen enhances the stability of the collagen triple helix. Previous X-ray diffraction analyses had demonstrated that the presence of an electron-withdrawing substituent on the pyrrolidine ring of proline residues has significant structural consequences [Panasik, N., Jr.; Ebe…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorSilsesquioxanes as Synthetic Platforms. Thermally Curable and Photocurable Inorganic/Organic HybridsAlan Sellinger and Richard M. LaineView Author Information Department of Materials Science and Engineering, Department of Chemistry, and…
The iron(II) spin state of Fe(C5H5N)2Ni(CN)4 changes from paramagnetic to diamagnetic when the temperature is lowered, while that of Fe(NH3)2Ni(CN)4·2C6H6 does not.