Materials Literature
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Fluorinated aliphatic polyurethanes based on hexamethylene diisocyanate (HDI) and polytetramethyl oxide (PTMO) were synthesized by using 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol (OF) or 2,2,3,3-tetrafluoro-1,4- butanediol (TF) as a chain extender. The polyurethanes chainextended with 1,4-butanediol (BD) were also pre…
The crystal structure of the third polymorph of the Cu(7)PSe(6) argyrodite compound, alpha-Cu(7)PSe(6), heptacopper phosphorus hexaselenide, is determined by means of single-crystal diffraction from twinned crystals and X-ray powder diffraction, with the help of extensive NMR measurements. In the low-temperature form,…
Thirty eight compounds composed of achiral banana-shaped molecules belonging to three new homologous series have been synthesized and their mesomorphic properties investigated. The mesophases have been characterized using a combination of polarized light microscopy, differential scanning calorimetry, miscibility metho…
The structural changes of rectorite Rar-1 during dehydroxylation have been studied using Infrared Emission Spectroscopy and have been compared to the changes observed for synthetic beidellite and paragonite. The hydroxyl-stretching region is characterised in all cases by a band around 3,640-3,650cm assigned to H-bonde…
The use of biodegradable nanoparticles loaded with 5-fluorouracil was investigated as a potential means to sustain the release of this drug. Nanoparticles prepared from four biodegradable polymers were loaded with 5-fluorouracil using three loading concentrations of drug and three different concentrations of added pol…
Abstract Infrared spectroscopy in the mid-IR region was used to follow the structural changes occurring in five Li-saturated dioctahedral smectites upon heating. The smectites included three montmorillonites, an Fe-beidellite and a ferruginous smectite. Fixation of Li + ions in the structure even upon heating at 120°C…
The crystallization and dielectric properties of SrO–BaO–Nb 2 O 5 –SiO 2 glass‐ceramics have been investigated. Glass‐ceramics that contain strontium barium niobate (SBN) as a primary crystalline phase, which has a tungsten bronze structure, are produced. The formation of crystalline secondary phases also has been stu…
The self-nucleation of branched polyethylene chains of different degrees of chain mobility was studied. The polyethylene block (PE block) within poly(styrene-b-ethylene-b-caprolactone) triblock copolymers (SEC) of varying compositions was studied. Differential scanning calorimetry was used to determine the self-nuclea…
The phase behavior of rod−plate mixtures was investigated using model systems of unambiguously rod- and plate-shaped colloids. Neither at equilibrium nor in the early stages of the phase separation process do we observe the theoretically disputed biaxial nematic phase. Instead, the mixtures show demixing into an isotr…
ZnO thin films have been grown on various substrates by femtosecond pulsed-laser deposition. According to optical microscopy and atomic force microscopy analyses, the production of droplets is not significant using femtosecond pulses. Smooth, dense, stoichiometric, crystalline, and textured hexagonal ZnO films are epi…
We present a model to more accurately describe the optical properties of a twisted nematic liquid crystal display (LCD). In particular, we study the optical properties of molecules near either edge of the LCD that are unable to twist and tilt under the application of an external elec- tric field. The properties of the…
Composite materials such as clay sheets intermixed with polymershave important potential applications; however, some fundamental properties remain to be understood. The equilibrium phase behavior of polymer–clay nanocomposites is examined here. The authors build on their recently proposed model that combines self-cons…
Phosphino carboxylic acid ester terminated G(0) compounds Si(CH(2))(3)SiMe(2)(C(6)H(4)CH(2)OC(O)(CH(2))(n)()CH(2)PPh(2)(4) (9a and 9b; n = 1, 2) and the carbosilane dendrimers Si(CH(2))(3)Si((CH(2))(3)SiMe(2)(C(6)H(4)CH(2)OC(O)(CH(2))(n)()CH(2) PPh(2))(3)(4) (10a and 10b; n = 1, 2) have been prepared as hemilabile nan…
Highly organized and textured CTAB templated silica films are made by the spin-coating technique. The HRTEM structural characterization of these films clearly shows the formation of a 3D hexagonal structure ( P 6 3 / mmc space group) due to the stabilization of a new phase which does not belong to the phase diagram of…
Hybrid organic−inorganic proton conducting gels (PWA/ICS−PPG or SiWA/ICS−PPG) were made from 3-isocyanatopropyltriethoxysilane and poly(propylene glycol)bis(2-aminopropyl ether), resulting in a hybrid silicon precursor (ICS−PPG) in which was dispersed phosphotungstic acid (PWA) or silicotungstic acid (SiWA) in ethanol…
The coexistence of ferromagnetic and paramagnetic phases in the $4f$-electron systems ${\mathrm{Gd}}_{5}{(\mathrm{S}\mathrm{i}}_{1.5}{\mathrm{Ge}}_{2.5})$ and ${\mathrm{Gd}}_{5}{(\mathrm{S}\mathrm{i}}_{2}{\mathrm{Ge}}_{2})$ during the magnetic-martensitic phase transition have been observed. A dc magnetic field revers…
A comparative study of the temperature-dependent Raman scattering of nanocrystalline and bulk silicon is presented. The nanocrystalline silicon samples were made by a cw laser annealing process, and the characteristic dimensions were determined with a phenomenological phonon confinement model. Experimental results ind…
The stability of charge-orbital ordering in a colossal magnetoresistance (CMR) manganite can be varied to a large extent by doping of Cr impurities on the Mn site. Most of the generic features seen in the CMR manganites, such as the submicrometric phase separation into metallic and insulating states, a resistivity-enh…
Nanocrystal shape can have a strong influence on the 2D and 3D structure of nanocrystal (NC) arrays, and it is important to understand its role if functional magnetic nanodevices are to be realized. Here is presented a detailed TEM analysis of 11 nm Co NCs and their effect on the superlattice assembly. Twins and stack…
The past decade has seen an explosive growth in atomic-level structures determined by X-ray crystallography. Synchrotron radiation and a number of technical advances related quite directly to its development have fueled this growth. With the most recent advances coming to be used collectively and new resources being b…