Materials Literature
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Ionene polymers with N,N ′ -( p -phenylene)dibenzamide linkages were synthesized in high yields by the copolymerization of 1,4-bis[4-(chloromethyl)benzamide]benzene and α,ω-ditertiary amines in N,N -dimethylformamide. The ionene polymers provided physical hydrogels under ca. 1−5 wt % of the concentrations after heatin…
A pi-extended, redox-active bridging ligand 4',5'-bis(propylthio)tetrathiafulvenyl[i]dipyrido[2,3-a:3',2'-c]phenazine (L) was prepared via direct Schiff-base condensation of the corresponding diamine-tetrathiafulvalene (TTF) precursor with 4,7-phenanthroline-5,6-dione. Reactions of L with [Ru(bpy)(2)Cl(2)] afforded it…
We present observations of resonance behavior in a torsional nanoelectromechanical device built with an individual single-walled carbon nanotube. The effect of applied torsional strain on the transport properties of the nanotube provides an electrical signal transducer and hence a means of measuring oscillation amplit…
Linear viscoelastic and dielectric behavior was examined for blends of cis -polyisoprene (PI-20; M PI = 19. 9 × 10 3 ) and poly(4- tert -butylstyrene) (PtBS-16; M PtBS = 16. 4 × 10 3 ) with the PtBS concentration of w PtBS = 30 and 50 wt %. At temperatures examined, T ≤ 120 °C, the PI/PtBS blends were in a statically…
Nano-Au/Co3O4 catalyst with high gold loading was found to be a good catalytic material for the elimination of trace ethylene (ppb) at ambient conditions. The gold nanoparticles dispersed on the support nano-Co3O4 surface contribute to this high activity at room temperature. The relatively rapid deactivation trend was…
The combination of a highly reactive monomer, 2-(methacryloyloxy)ethyl succinate (MES), and active catalyst systems, e.g., Cu(I) complexed with 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA), allows rapid formation of poly(carboxylic acid) brushes by atom transfer radical polymerization (ATRP) from a surface. A…
Highly nanostructured hybrid materials were prepared by the intercalation into the interlayer spaces of kaolinite of ionic liquids based on imidazolium derivatives. Their structure, thermal behavior, and composition were characterized by a range of methods, including X-ray diffraction, solid-state NMR, thermal gravime…
The objective of this work was to investigate the effect of fatty acid (FA) type and content on mechanical properties, water vapor permeability and oxygen permeability of hydroxypropyl methycellulose (HPMC)-beeswax (BW) stand-alone edible films. The effect of these films formed as coatings on the postharvest quality o…
A new supramolecular system, consisting of an expanded porphyrin, cyclo[8]pyrrole (C8) and a pyrene carboxylate (Py) is capable not only of electron transfer upon photoexcitation, but results in "umpolung" or a reversal of the predicted charge-separation behavior in that the higher energy radical ion pair, C8.+-Py.- (…
The preparation and the properties of gold nanoparticles (Au NPs) protected by perfluorinated amphiphiles are described. The thiols were devised to form a perfluorinated region close to the gold surface and to have a hydrophilic portion in contact with the bulk solvent to impart solubility in water. The monolayer prot…
Novel biodegradable amphiphilic ABC 3-miktoarm star terpolymers composed of poly(ε-caprolactone) (PCL), monomethoxy poly(ethylene glycol) (MPEG), and polyphosphoester (PPE) were synthesized by a combination of ring-opening polymerization and “click” chemistry. MPEG was first end-capped by epoxide ring, which was opene…
A novel layer-by-layer approach has been developed to synthesize polycrystalline SnO(2) hollow spheres with tunable shell thickness and size using SiO(2) spheres as a template. The surface of the SiO(2) spheres has been first modified by the polyelectrolyte, and subsequently, the compact SnO(2) layer has deposited on…
We have studied the atomic-scale structure of the Mo6S6 nanowires using scanning tunneling microscopy and spectroscopy (STM and STS) and density functional theory (DFT). A novel synthesis route based on metallic Mo precursors is presented for the selective formation of elementary pure Mo6S6 nanowires. The Mo6S6 nanowi…
The crystal structure of the Sr 2 Fe 2 O 5 brownmillerite has been investigated using electron diffraction and high resolution electron microscopy. The Sr 2 Fe 2 O 5 structure demonstrates two-dimensional order: the tetrahedral chains with two mirror-related configurations (L and R) are arranged within the tetrahedral…
We present a contrast variation small-angle neutron scattering (SANS) study of a series of neutral PAMAM dendrimers in aqueous solutions using three different generations (G4−6) at a concentration of about 10 mg/mL. Varying the solvent hydrogen−deuterium ratio, the scattering contributions from the water molecules and…
We investigate a series of poly(amidoamine) starburst dendrimers (PAMAM) of different generations in acidic, aqueous solutions using small-angle neutron scattering (SANS). While the overall molecular size is found to be practically unaffected by a pD change, a strong generational dependence of counterion association i…
Following our recent theoretical studies [M. G. Silveirinha, C. A. Fernandes, Phys. Rev. B, 78, 033108, 2008], it is experimentally verified that an array of crossed metallic wires may behave as a nonresonant material with extremely large index of refraction at microwaves, and may enable the realization of ultra-subwa…
Polycrystalline samples of LaSr1-xBaxNiO4 show a crossover from a state with metallic transport properties for x = 0 to an insulating state as x -> 1. The end member LaBaNiO4 with a nominal nickel Ni 3d7 configuration might therefore be regarded as a candidate for an antiferromagnetic insulator. However, we do not obs…
We show that the ground state of zigzag bilayer graphene nanoribbons is non-magnetic. It also possesses a finite gap, which has a non-monotonic dependence with the width as a consequence of the competition between bulk and strongly attractive edge interactions. All results were obtained using {ab initio} total energy…
A series of lanthanide adducts with different amounts of 1,10-phenanthroline, chloride ions, and water molecules in the inner and outer coordination spheres are investigated with the aim of relating the chemical bonding patternin the crystals to the luminescence properties of the Eu ion: [LnCl1Phen2(H2O)3]Cl2(H2O) (Ln…