Materials Literature
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We report a study of the self-condensing group transfer copolymerization of the initiator−monomer (“inimer”) 2-(2-methyl-1-triethylsiloxy-1-propenyloxy)ethyl methacrylate (MTSHEMA) with methyl methacrylate (MMA). The highly branched polymethacrylates were characterized by multidetector SEC and NMR. Kinetic measurement…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTTemperature Dependence of Segmental and Terminal Relaxation in Atactic Polypropylene MeltsC. M. Roland, K. L. Ngai, P. G. Santangelo, XH. Qiu, M. D. Ediger, and D. J. PlazekView Author Information Naval Research Laboratory, Washingt…
Abstract The effect of blending crosslinked linear low‐density polyethylene (cLLDPE) on the rheological properties and foam processability of linear low‐density polyethylene was studied. A small addition of cLLDPE, which had a low density of crosslink points, enhanced strain‐hardening behavior in the elongational visc…
Quasi-monodisperse emulsions can be obtained by shearing a crude polydisperse one within a very narrow gap ( Langmuir 1997, 4600−4613). In this paper, we apply the emulsifying technique developed for simple emulsions to fabricate double emulsions of controlled size. We first prepare quasi-monodisperse and concentrated…
The structural and thermodynamic properties of mixtures of colloidal spheres and nonadsorbing polymer chains are studied within a general two-component macromolecular liquid state approach applicable for all size asymmetry ratios. The dilute limits, when one of the components is at infinite dilution but the other conc…
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Mesoporous silica can be formed with amphiphilic molecules acting as structure-directing templates in dilute systems. The templating properties of five related triblock copolymers, (EO) x −(PO) y −(EO) x (Pluronic L101, P103, P104, P105, and F108), have been investigated regarding the length of the EO blocks as well a…
Energy landscape theory is becoming increasingly important to explain the behavior of proteins, clusters, and glasses. In this Perspective, [ Brooks et al .][1] chart recent progress in these areas spanning biology, chemistry, and physics. [1]: http://www.sciencemag.org/cgi/content/full/293/5530/612
Utilizing Co/Al$_2$O$_3$/Co magnetic tunnel junctions (MTJs) with Co electrodes of different crystalline phases, a clear relationship between electrode structure and junction transport properties is presented. For junctions with one fcc(111) textured and one polycrystalline (poly-phase and poly-directional) Co electro…
A magnetic "spin filter" tunnel barrier, sandwiched between a non-magnetic metal and a magnetic metal, is used to create a new magnetoresistive tunnel device, somewhat analogous to an optical polarizer-analyzer configuration. The resistance of these trilayer structures depends on the relative magnetization orientation…
A new method is presented for mesoscopic simulations of particle dispersions in nematic liquid-crystal solvents. It allows efficient first-principles simulations of the dispersions involving many particles with many-body interactions mediated by the solvents. A simple demonstration is shown for the aggregation process…
Regime transitions of poly[(S)-lactide] (PLA) crystal growth from the melt were investigated by studying the morphological changes and carrying out kinetic analysis using microscopic techniques. PLA thin films with an average layer thickness of 100 nm were isothermally crystallized at a given crystallization temperatu…
Three novel mixed-ligand lithium aggregates, [(mu(3)-EDBP)Li(2)](2)[(mu(3)-(n)Bu)Li(0.5Et(2)O)](2) (1), [(mu(3)-EDBP)Li(2)](2)[(mu(3)-OBn)Li](2) (2), and [(mu(3)-EDBP)Li(2)](2)[(mu(3)-OCH(2)CH(2)OCH(2)CH(3))Li](2) (3), have been synthesized and structurally characterized. The reaction of 2,2'-ethylidene-bis(4,6-di-ter…
Poly(ethylene oxide) (PEO), soluble in both water and many organic solvents, is grafted onto single-walled carbon nanotubes (SWNTs), and aggregation behaviors of the resulting PEO- graft -SWNT in solutions and in Langmuir−Blodgett (LB) films are investigated. SWNTs, cleaved by acid, are dispersed relatively well in DM…
We investigated magnetic, magnetotransport and magnetostriction properties of the A-type antiferromagnet Pr$_{0.46}$Sr$_{0.54}$MnO$_3$ which undergoes a first order paramagnetic-antiferromagnetic transition below T$_N$ = 210 K while cooling and T$_N$ = 215 K while warming. The zero field ($μ_0$H = 0 T) resistivity sho…
We perform molecular dynamics simulations of an idealized polymer melt surrounding a nanoscopic filler particle. We show that the glass transition temperature T(g) of the melt can be shifted to either higher or lower temperatures by tuning the interactions between polymer and filler. A gradual change of the polymer dy…
A donor−chromophore−acceptor triad (D−C−A) in which the chromophore is a Pt diimine bis(acetylide) moiety (red), the donor is phenothiazine (blue), and the acceptor is nitrophenyl (green) has been synthesized and studied spectroscopically. Irradiation leads to a charge-separated state that has a 70 ns lifetime as meas…
Optical conductivity measurements on the perovskite-related oxide CaCu3Ti4O12 provide a hint of the physics underlying the observed giant dielectric effect in this material. A low-frequency vibration displays anomalous behavior, implying that there is a redistribution of charge within the unit cell at low temperature.…
We investigate the mechanism of the resonant x-ray scattering on the Ti K edge region of ${\mathrm{YTiO}}_{3}$ using the band structure calculation combined with the local density approximation. A large intensity is obtained for the orbital superlattice spots. The calculated spectra consist of several peaks as a funct…
We have determined the adsorptive capacity of Xe on the different groups of binding sites available to this atom on a sample of single-walled carbon nanotube (SWNT) bundles. The SWNT's used were not treated after production: hence, the caps at the ends of each of the tubes remain intact. By comparing these experimenta…