Materials Literature
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The isothermal crystallization of three different types of poly[ε-caprolactone- co -ethylene glycol] (PCL−PEG) incompatible block copolymers [A−B, (A) 2 −B, and A−B−A] was investigated using DSC. The PEG weight fraction in the copolymers was slightly varied from 18 to 22 wt %. It was established that the kinetic param…
Solutions containing divalent metal [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+] chlorides and CrCl3 6H2O were titrated with NaOH to yield, for M(II) = Zn, Co, and Ni, hydrotalcite-like layered double hydroxides (LDHs), [[M(II)]1-z[Cr(III)]z(OH)2][Cl]z yH2O, in a single step, without intermediate formation of chromium hydro…
The combination of two metals in an oxide matrix can produce materials with novel physical and chemical properties. The reactivity of a series of cobalt and nickel molybdates (α-AMoO 4, β-AMoO 4, and AMoO 4 · n H 2 O; A = Co or Ni) toward H 2 and H 2 S was examined using temperature programmed reduction (TPR), synchro…
Extensive molecular dynamics simulations are carried out to study static and dynamic properties of symmetric diblock copolymer melts, both in the disordered and in the lamellar phases. The lamellar phase is constructed using the natural lamellar spacing, determined from constant pressure simulations. The non-Gaussian…
Poly(3,4-ethylenedioxythiophene)/poly(styrene-4-sulfonate) (PEDOT/PSS) composites have been prepared from aqueous and aqueous acetonitrile solutions of EDOT and NaPSS by oxidation using Fe(III) salts. Powders with PEDOT to PSS ratios ranging from 0.3 to 4.2 and electronic conductivities as high as 10 S cm - 1 have bee…
Inclusion complex formation between polyaniline with emeraldine base and β-cyclodextrin has been studied by the frequency-domain electric birefringence (FEB) spectroscopy in a solution of N -methyl-2-pyrrolidone (NMP) and by scanning tunneling microscopy (STM). The FEB results show that polyaniline in the solution wit…
Structural parameters for ordered mesoporous materials are shown to be strongly interrelated as a result of their well-defined structures. Equations for mesoporous materials with hexagonal arrays of uniform pores (e.g., MCM-41 and SBA-15) are presented, which can be used to calculate the pore size, pore wall thickness…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTThe Effect of Temperature Gradient on the Microdomain Orientation of Diblock Copolymers Undergoing an Order−Disorder TransitionTakeji Hashimoto, Jeffrey Bodycomb, Yoshinori Funaki, and Kohtaro KimishimaView Author Information Hashim…
The glass transition temperature of wheat gluten, plasticized with water, glycerol, or sorbitol, has been studied using dynamical mechanical thermal analysis. For the three plasticizers studied, the general behavior of the glass transition temperature broadly followed the Couchman-Karasz relation using a wheat gluten…
Huge built-in electric fields have been predicted to exist in wurtzite III-V nitrides thin films and multilayers. Such fields originate from heterointerface discontinuities of the macroscopic bulk polarization of the nitrides. Here we discuss the background theory, the role of spontaneous polarization in this context,…
Solutions containing di- and trivalent metal chlorides [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+; M(III) = Al3+, Fe3+] were titrated with NaOH to yield hydrotalcite-like layered double hydroxides (LDH), [[M(II)]1-x[M(III)]x(OH)2][Cl]x yH2O, by way of M(III) hydroxide/hydrous oxide intermediates. Analysis of the resultant…
We investigate the breakdown of disordered networks under the action of an increasing external---mechanical or electrical---force. We perform a mean-field analysis and estimate scaling exponents for the approach to the instability. By simulating two-dimensional models of electric breakdown and fracture we observe that…
The theoretical and experimental status of surfactant mediated semiconductor epitaxial growth is reviewed. We discuss homoepitaxy as well as heteroepitaxy, and emphasize in particular issues related to the mechanism by which surfactants suppress growth of three dimensional islands in heteroepitaxy. We argue that the d…
Nanoscale control of the polymerization of silicon and oxygen determines the structures and properties of a wide range of siloxane-based materials, including glasses, ceramics, mesoporous molecular sieves and catalysts, elastomers, resins, insulators, optical coatings, and photoluminescent polymers. In contrast to ant…
We report on the development of conductive polymer-based cladding layers for use in multilayered electro-optic (EO) device structures. The waveguide claddings used in these studies were based on blends formed from the conductive polymer poly (ethylene dioxythiophene) with poly (vinylalcohol). Thin films of the blended…
Porous silicon (PS) with strong and nondegrading photoluminescence (PL) is prepared by iron-passivating hydrothermal etching. The PL peak intensity of freshly as-prepared PS is as ∼2 times strong as that of conventionally anodized PS. This peak intensity reaches a saturation after the samples are annealed at 120 °C fo…
The longitudinal magnetoresistance (LMR) of thin films of the putative half-metallic ferromagnet CrO2 deposited by chemical vapor deposition onto TiO2/Si(111) substrates has been measured in the temperature range 0.55 K<T<4.2 K in magnetic fields up to 7 T. The dependence of the LMR on small changes in t…
Experimental studies on the morphology and thermal and electrooptical behavior of PDLC films consisting droplets of nematic LC (6CB) up to a 40% weight fraction in a polyester resin matrix crosslinked by diacrylane are presented. The PDLC samples were prepared by LC separation from a solution in a UV-polymerizing olig…
It was shown that the uniaxial compressive stress applied perpendicular to the electric field strongly changes the dielectric and electromechanical properties of relaxor ferroelectric 0.9PMN:0.1PT at temperatures around its dielectric constant maximum, Tm. This includes: (i) a shift of the temperature of the electric…
The vitrification line for the ternary system of polysulfone (PSf)/N-methyl-2-pyrrolidinone (NMP)/water was determined by differential scanning calorimeter (DSC) measurements with varying compositions. Pure PSf showed both α- and β-transition temperatures (Tg,α = 187.5°C, Tg,β = −21.4°C). The Tg,α of PSf decreased wit…