Materials Literature
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Molecular dynamics simulations were performed for a polymer melt. In quiescent states, the inter-chain interaction energy supported by each particle takes relatively large values persistently for long times if the particle is close to an entanglement. Thus, if the interaction is averaged over appropriate time interval…
Uniaxial elongation and swelling of well-defined fully conjugated poly(3-octylthiophene) gels of various functionalities and cross-link concentrations are studied above the melting temperature. The gels exhibit rubber elasticity (elastic modulus E in the range 0.2 < E < 0.7 MPa) and swell in chloroform. A linear relat…
This report describes the synthesis and characterization of a series of octaethylporphyrin derivatives in which the porphyrin pi-network is connected to phenyl, 3-fluoranthenyl, or 1-pyrenyl aromatic systems through a meso amino or amido nitrogen. Metal-free bases and zinc(II) and iron(III) complexes have been obtaine…
For the first time, mixed-addenda vanadium-substituted polyfluorooxometalates, PFOMs, have been synthesized. Depending on the workup procedure used, two types of compounds were prepared. The first PFOM was a quasi Wells--Dawson type compound, [H2F6NaVVW17O56]8-, and the second a mixture of vanadium-substituted polyflu…
The conversion of 2-chloropropane (2-CP) in the presence of oxygen has been investigated over a number of catalysts including alumina and alumina-supported copper chloride, manganese tungstate, mixed manganese−aluminum oxide, silica−alumina, and ZSM5 zeolite. Dehydrochlorination to propene + HCl is predominant, but ot…
Sequence distribution and chemical structure of mass-selected macromolecules of poly(3-hydroxybutyrate- co -3-hydroxyvalerate), PHBV, biopolyester macroinitiator obtained by partial alkaline depolymerization of natural PHBV containing 5 mol % of HV units was determined by electrospray ionization multistage mass spectr…
The chloroiron corrolates of 2,3,7,8,12,13,17,18-octamethyl- and 7,13-dimethyl-2,3,8,12,17,18-hexaethylcorrole ([(Me8C)FeCl] and [(7,13-Me2Et6C)FeCl], respectively) and their bisimidazole complexes have been investigated by NMR spectroscopy as a function of temperature, and by EPR spectroscopy at 4.2 K. Magnetic susce…
We investigate the formation and coalescence of surface relief structures in symmetric diblock copolymers films of poly(styrene- b -2-vinylpyridine) (PS−PVP) on chemically patterned surfaces. The substrates have patterns of self-assembled monolayers (SAMs) produced by microcontact printing HO-terminated (HO−) SAM stri…
Coronal structures of the micelles spontaneously formed in water by poly(ethylene oxide)- b -polybutadiene (PEO−PB) were investigated using small-angle neutron scattering (SANS). Selective deuterium labeling of the hydrophobic PB block was employed to enhance the neutron scattering contrast between the PEO and PB segm…
Block copolymers with semifluorinated monodendron side groups were synthesized by attachment of a first generation 2- or 3-armed monodendron acid chloride to a hydroxylated poly(styrene- b -1,2/3,4-isoprene). A convergent growth strategy was developed to synthesize the monodendron groups in good yield using an approac…
Solid-solid thermal boundary resistance Rb plays an important role in determining heat flow, both in cryogenic and room-temperature applications, such as very large scale integrated circuitry, superlattices, and superconductors. The acoustic mismatch model (AMM) and the related diffuse mismatch model (DMM) describe th…
A theoretical model has been developed to describe the bulk-degradation behavior of model PEG- b -PLA hydrogels. Utilizing a statistical approach to predict the cleavage of cross-links within these networks, the model accounts for both structural and kinetic issues during the degradation and, from direct comparison, c…
Several versions of free-volume theory have been proposed to correlate or predict the solvent diffusion coefficient of a polymer/solvent system. The quantity of free volume is usually determined by the Williams–Landel–Ferry (WLF) equation from viscosity data of the pure component in these theories. Free volume has bee…
ADVERTISEMENT RETURN TO ISSUEPREVNoteDynamic Properties of an Amorphous Polyethylene NanofiberVisit Vao-soongnern and Wayne L. MatticeView Author Information Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909 Cite this: Langmuir 2000, 16, 16, 6757–6758Publication Date (Web):July 11, 2000Pub…
An average structure of incommensurately modulated monoclinic InTi 0.75 Fe 0.25 O 3.375 was determined using single-crystal X-ray diffraction. Unit cell parameters are a = 5.9207(8), b = 3.4249(5), c = 6.3836(9), and β = 107.96(1) with Z = 2, and the space group is C 2/ m . The structure with pseudorhombohedral symmet…
The electrooxidation behavior of thiophene and 3-methylthiophene on a Pt surface in an acetonitrile + tetrabutylammonium tetrafluoroborate solution were investigated. The electropolymerization of these monomers was studied in neutral, acidic, and basic media. The effects of thiophene concentration and the added acid w…
Using the full-potential linearized augmented-plane-wave (FLAPW) method, the mechanism of the rutile-CaCl 2 phase transition of RuO 2 and the phase stability of β-PtO 2 are investigated. The local density functional calculations predict quantities such as lattice constants, bulk moduli, and phonon frequencies in good…
An optical microscopy study and a micro-Raman spectroscopy study were carried out on polyethylene samples subjected to an environmental stress crack resistance (ESCR) test. The aim was to elucidate the molecular deformation mechanisms associated with the failure process. It has been shown that in the early stages of t…
The epoxidation of trans-cyclooctene (trans-1) with the MTO/H(2)O(2), MTO/UHP, and NaY/MTO/H(2)O(2) oxidants leads to a mixture of trans/cis-olefins 1, trans/cis-epoxides 2, and the cis-diol 3. While the oxygen transfer proceeds stereoselectively, the monoperoxo rhenium complex A, which is generated in situ during the…
Specimens treated with solutions of an epoxy analogue molecule, diethanolamine (DEA), have been studied by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF−SIMS). The initial substrates were of two different types: grit-blasted aluminum and aluminum coated with an organosi…