Materials Literature
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The foams of poly(ethylene terephthalate) (PET) and polycarbonate (PC) are prepared by rapid depressurization of CO 2 -saturated molten resin. It is found that the foamable temperature and pressure for PET and PC are nearly identical, and the attainable expansion ratio of the produced foam is generally less than 10. T…
Monometal hydrotalcite-like compounds of Co II 0.74 Co III 0.26 (OH) 2.01 (NO 3 ) 0.21 (CO 3 ) 0.02 ·0.6H 2 O and Co II 0.74 Co III 0.26 (OH) 1.99 (CO 3 ) 0.13 (NO 3 ) 0.01 ·0.7H 2 O have been prepared via precipitation and anion-exchange methods. After being heated at 150−600 °C, the two precursor compounds were oxid…
Thin films produced by plasma-enhanced chemical vapor deposition (PECVD) have potential application as conformal coatings on implantable devices with complex topologies and small dimensions. Coatings on such devices need to be biocompatible, insulating, and flexible enough to minimize static forces on the surrounding…
We investigate, via three-dimensional atomistic computer simulations, phase separation in an alloy under external load. A regular two-dimensional array of cylindrical precipitates, forming a mesoscopic precipitate lattice, evolves in the case of applied tensile stress by the movement of mesoscopic lattice defects. A s…
We report extensive self-consistent calculations of jellium surface energies, by going beyond the local-density approximation. The density-response function of a bounded free-electron gas is evaluated within the random-phase approximation, with use of self-consistent electron density profiles. The exchange-correlation…
The effect of surfactants on the thermodynamics and kinetics of semiconductor heteroepitaxy is briefly discussed. It is argued that the way the surfactants suppress the thermodynamic driving force for 3D islanding depends on the mechanism of exchange of overlayer and surfactant atoms. If the overlayer atoms occupy bul…
The atomic structures of nanocrystalline powders of ceria, CeO 2, and ceria-zirconia solid solution, (Ce,Zr)O 2, were studied by the pulsed neutron diffraction technique. Ceria is used as an oxygen storage component in automotive exhaust emission control systems, but the degradation of its oxygen storage capacity (OSC…
Introduction to glassy polymers The glass transition When a polymer is cooled down from the liquid or rubbery state, it becomes much stiffer as it goes through a certain temperature range. This stiffening is the result of one of two possible events: crystallization or glass transition. For crystallization to occur, th…
Waste leather granules were incorporated into poly(vinyl chloride) plastisols containing di-octyl phthalate as plasticizer. The rheological behavior and gelling characteristics of plastisols were investigated and the filled samples were tested for their physicomechnical properties. It was found that density, wear resi…
We have developed a novel approach for forming dendrimer monolayers. A Lys-Lys-Glu tripeptide with a dioctadecylamino tail at the C-terminal and an acetyl head at the N-terminal was newly synthesized as a unit. Three generations of the dendrimers were successfully synthesized by stepwise deprotection and condensation.…
A new class of surface-modified dendrimers has been prepared by reactions of 8 equiv of the terpyridine-functionalized polyether monodendrons with a polyhedral oligomeric silsesquioxane (POSS) core. Subsequent reactions of these spherically shaped organic dendrimers with Ru(II)-based precursors afford photo- and redox…
Homogeneous DNA hybridization assay based on luminescence resonance energy transfer (LRET) from a tetradentate beta-diketonate europium chelate, 4,4'-bis(1' ',1' ',1' ',2' ',2' ',3' ',3' '-heptafluoro-4' ',6' '-hexanedion-6' '-yl)-chlorosulfo-o-terphenyl (BHHCT)-Eu(3+) (lambda(ex) = 340 nm and lambda(em) = 615 nm), to…
The electronic structures of a series of carbon nanotubes with different sizes, chiralities, ends, and bond lengths are studied systematically. Their absorption spectra are calculated with the localized density matrix method. The semiempirical model PM3 is employed in the calculation. The nature of optical excitations…
Reaction of M(NO3)2.xH2O (M = Mn, Co, Ni, Cu, Zn) with 3-diphenylamino-4-hydroxycyclobut-3-ene-1,2-dione (diphenylaminosquarate) produces the neutral polymeric species (M[mu-(C6H5)2NC4O3]2[H2O]2)n [M = Mn (1), Cu (2)]; (M[mu-(C6H5)2NC4O3][(C6H5)2NC4O3][H2O]3)n [M = Co (3), Zn (4)]; and in the case of Ni, the salt [Ni(…
The H-bond interaction between the tautomeric cytosine-modeling system, 2-hydroxypyridine (2HP)/2-oxopyridine (2OP), with water is investigated using matrix-isolation FT-IR spectroscopy and ab initio calculations performed with the RHF and MP2 methods and the DFT method with the B3-LYP hybrid functional. Equilibrium s…
Polypropylene (PP) was modified by solid-phase graft copolymerization with maleic anhydride (MAH) and styrene (St), using benzoyl peroxide as the initiator and xylene as the interfacial agent. Effects of various factors such as monomer concentration, monomer ratio, initiator concentration on grafting percentage, and a…
Chemical hydrogels based on poly(vinyl alcohol), PVA, were obtained by reacting telechelic PVA bearing aldehydic groups at both ends of the chain with the hydroxylic moiety of the polymer. These networks were studied by dynamic light scattering around the sol−gel transition threshold. The auto-correlation function, g…
The unprecedented use of polymerizable hydrocarbon tail systems containing 1,3-diene groups for the design of thermotropic and lyotropic liquid crystal (LC) monomers is described. Cross-linkable LC dienes are synthesized by attaching LC core units to modular ω-bromoalka-1,3-diene tails of variable length. These modula…
Au nanoparticles (particle diameter ∼2 nm) prepared by thiocyanate reduction method are too small to exhibit the characteristic surface plasmon band. Addition of Rhodamine 6G (Rh 6G) to the colloidal gold solution brings about significant changes in the absorption spectrum. Two distinct peaks appear at 507 and 537 nm.…
The first-order hyperpolarizabilities of a series of mono-, bi-, and trinuclear organometallic compounds were determined using Hyper-Rayleigh Scattering at 1.06 μm. The molecular nonlinear optical responses (NLO) were investigated for various combinations of iron(II) and iron(III), including mixed-valence iron(II)/iro…