Materials Literature
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[reaction: see text] A dendrimer wherein the branching points are mechanical in nature has been synthesized. It contains two identical covalently linked bis-dendrons and a core unit fused to two rings that encircle the two bis-dendrons. A "threading-followed-by-stoppering" approach is used in the template-directed syn…
Total neutron diffraction has yielded accurate bond lengths, Ag-C = Ag-N = 2.06 A and C-N = 1.16 A, for the disordered crystalline solid AgCN. This information cannot be obtained from analysis of Bragg scattering studies, because the (-Ag-CN-)(n) chains are randomly displaced along the chain axis relative to each othe…
Octahedral coordination of molybdenum(III) is achieved by limiting the amount of cyanide available upon complex formation. Reaction of Mo(CF(3)SO(3))(3) with LiCN in DMF affords Li(3)[Mo(CN)(6)] x 6DMF (1), featuring the previously unknown octahedral complex [Mo(CN)(6)](3-). The complex exhibits a room-temperature mom…
A triblock copolymer (PCL−PPG−PCL, M n = 1.38 × 10 4 ) of poly(ε-caprolactone) (PCL) and poly(propylene glycol) (PPG) was synthesized by ring-opening polymerization of ε-caprolactone. Cyclodextrin (CD)-type-dependent formation of inclusion complexes (ICs) between cyclodextrins and this triblock copolymer was studied.…
The relative stability between the ${P6}_{3}/m$ and ${P6}_{3}$ structures of \ensuremath{\beta}-silicon nitride $(\ensuremath{\beta}\ensuremath{-}{\mathrm{Si}}_{3}{\mathrm{N}}_{4})$ crystal has been examined using the ab initio pseudopotential method. We have performed the relaxation of atomic positions in the unit ce…
Through its several orders of magnitude signal enhancement over normal Raman, surface-enhanced Raman spectroscopy (SERS) provides an opportunity to extend the benefits of vibrational spectroscopy to trace level detection. SERS in particular holds great potential for biological sensing due to the weak Raman bands of wa…
We investigate the influence of chain architecture on the microscopic deformation and fracture mechanisms of poly(vinylcyclohexane)−poly(ethylene) (PCHE−PE) block copolymer thin films. To investigate the correlation between the mechanical and fracture properties of the polymer and its chain architecture, a “metal grid…
The interactions between polyamidoamine starburst dendrimers (SBDs) and vesicles consisting of dimyristoylphosphatidylcholine (DMPC) and its phosphatidylcholate salt (DMPA-Na) in various relative ratios (from 0% to 40% of DMPA-Na) were studied by electron paramagnetic resonance (EPR) and by transmission electron micro…
We determine the equilibria of a rigid loop in the plane, subject to the constraints of fixed length and fixed enclosed area. Rigidity is characterized by an energy functional quadratic in the curvature of the loop. We find that the area constraint gives rise to equilibria with remarkable geometrical properties; not o…
Gels and semicrystalline clathrate samples formed by syndiotactic polystyrene (sPS) with 1,2-dichloroethane (DCE) and 1-chloropropane (CP) have been investigated, for the entire composition range from pure solvent to pure polymer, by wide-angle X-ray diffraction (WAXD) and Fourier transform infrared spectroscopy (FTIR…
During a cold plasma treatment, a polymer surface is involved in many reactions, such as degradation and functionalization. CO 2 plasma treatment leads to carboxylic acid function fixation onto high-density polyethylene surface. Attempts are done to optimize the concentration of these last functions by using CO 2 /H 2…
The electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ is studied by angle-resolved photoelectron spectroscopy (ARPES). The experimental spectra reveal significant discrepancies to band theory. We demonstrate that the measured dispersions can be consistently mapped onto the one-dimensional Hu…
Magnetotransport behavior is investigated in detail across a first-order magnetic phase transition from a ferromagnetic state to an antiferromagnetic state in a polycrystalline $\mathrm{Ce}({\mathrm{Fe}}_{0.96}{\mathrm{Al}}_{0.04}{)}_{2}$ sample. The study clearly brings out various generic features associated with a…
We calculate the imaginary part of the frequency-dependent dielectric function of bulk silicon by applying time-dependent density-functional theory based on the exact-exchange (EXX) Kohn-Sham (KS) band structure and the adiabatic local-density approximation (ALDA) kernel. The position of the E2 absorption peak calcula…
We present a continuum phase-field model of crack propagation. It includes a phase-field that is proportional to the mass density and a displacement field that is governed by linear elastic theory. Generic macroscopic crack growth laws emerge naturally from this model. In contrast to classical continuum fracture mecha…
Hall, resistivity, magnetization, and thermoelectric power measurements were performed on single crystals of the highly anisotropic layered metal LaSb2. A 100-fold linear magnetoresistance (MR) was observed in fields up to 45 T, with no indication of saturation. We show that the MR is associated with a magnetic-field-…
Following a previous work (Tissot, I.; Lefebvre, F.; Bourgeat-Lami, E. Macromolecules 2001, submitted for publication), polystyrene latex particles containing silanol groups have been synthesized in emulsion polymerization using 3-(trimethoxysilyl)propyl methacrylate (MPS) as a functional comonomer. The surface proper…
Abstract The properties of polyurethane (PU) nanocomposites with three different organoclays were compared in terms of their thermal stabilities, mechanical properties, morphologies, and gas permeabilities. Hexadecylamine–montmorillonite, dodecyltrimethyl ammonium–montmorillonite, and Cloisite 25A were used as organoc…
A novel nanocomposite containing polyethylene and polyhedral oligomeric silsesquioxane (POSS) nanoparticles has been characterized using wide-angle X-ray scattering (WAXS). In copolymers formed between ethylene and POSS containing macromonomers, the POSS units, attached as pendant groups off the polyethylene backbones…
We employ density functional and quantum Monte Carlo calculations to show that significant changes occur in the gap of fully hydrogenated nanoclusters when the surface contains passivants other than hydrogen, in particular atomic oxygen. In the case of oxygen, the gap reduction computed as a function of the nanocluste…