Materials Literature
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A transmission electron microscopy examination of hydrothermally produced carbon nanofibres/nanotubes with outer diameter 50–200 nm suggests that the tube walls are inclined with respect to the tube axis. The apex angles are in the range 8°–16°. The structure of these tubes and their growth mechanism can be described…
An alternating poly(ester amide) constituted by 6-amino-1-hexanol and glutaric units has been synthesized by different ways involving solution or thermal polycondensation. Results of the synthesis are compared, and the occurrence of a thermal degradation through imide ring formation is demonstrated. Hydrolytic and enz…
In this paper we present the results of the synthesis and characterization of nanocrystalline La 1 - x Na x MnO 3+ δ samples. Two synthetic routes were employed: polyacrylamide-based sol−gel and propellant synthesis. Pure, single-phase materials were obtained with grain size around 35 nm for the sol−gel samples and ar…
The diameter of high-pressure CO (HiPco) single-wall carbon nanotubes (SWNTs) has been enlarged by treating them with nitric acid and oxygen, and the diameter enlargement is related to the nitric acid refluxing time. Raman spectra (exciting wavelength 488 nm) and transmission electron microscopy showed that the 0.8−1.…
X-ray diffraction analyses of the clay-sized fraction of sediments from the Nankai Trough and Shikoku Basin (Sites 1173, 1174, and 1177 of the Ocean Drilling Program) reveal spatial and temporal trends in clay minerals and diagenesis. More detrital smectite was transported into the Shikoku Basin during the early–middl…
The segmental dynamics of miscible polymer blends have been the focus of much recent research since the two constituents typically appear to experience different average dynamic environments. It has been suggested that these results can be attributed to concentration fluctuations coupled to chain connectivity effects.…
Abstract The X‐ray structure of the sodium salt of [Gd(DOTP)] 5− shows two different chelates, [Gd (1) (DOTP)] 5− and [Gd (2) (DOTP)] 5− , bound at either surface of a sheet formed by a cluster of hydrated Na + ions. Each [Gd (1) (DOTP)] 5− anion binds directly to four Na + ions of this cluster through the free oxygen…
This study demonstrates that bridging (and possibly knotted looping) pentablock configurations in CEC/CECEC (triblock/pentablock) blends play significant roles in the shear-induced alignment and tensile mechanical properties of lamellae-forming block copolymers. Adding just 15 wt % pentablock to the triblock copolymer…
We report on the competitive role of hydrogen bonding and electrostatic interactions in growth and stability of polyelectrolyte multilayers (PEMs) in a wide range of pH. The system was a cationic copolymer of acrylamide and dimethyldiallylammonium chloride (PAAm-DMDAAC) containing 50% cationic units and poly(methacryl…
New results of dielectric spectroscopy in semicrystalline nylon-6 samples with different moisture contents are presented by using a wide frequency (10 -2 −3 × 10 6 Hz) and temperature range (133−433 K). The dielectric absorption spectra in frequency domain are decomposed in Cole−Cole distributions corresponding to the…
The study computes evolutionary tracks for 13-16 mass values (depending on the assumed chemical composition) in the range 0.15-1.25 solar mass for each of 10 metallicities between -2.26 and -0.47 (Fe/H). A total of 46 tracks are evolved to the helium flash point. The properties of selected models along the entire evol…
Using light scattering spectroscopy, we demonstrate that a transition from small molecular behavior to Rouse dynamics in poly(dimethylsiloxane) (PDMS) is a smooth function of molecular weight, M w . The asymptotic Rouse behavior is achieved when the chain begins to display Gaussian behavior. Surprisingly, the molecula…
Individual PbSe nanocrystals (NCs) were prepared by a chemical reaction between lead-cyclohexanebutirate and tri-butyl-phosphine/selenium precursors in a tri-octyl-phosphine oxide/tri-butyl-phosphine surfactant, at 118 °C. Increasing precursor concentration, accompanied by an additional heating, up to 150 °C, enabled…
Poly(lactic acid) (PLA) were grafted to both ends of Pluronic F127 (PEO−PPO−PEO) to produce novel amphiphilic PLA-F127−PLA block copolymers. The aggregation behaviors of three different modified polymers were examined by laser light scattering and transmission electron microscopic techniques. The structure of aggregat…
We observed novel nanoscale surface structures of segregated pinned micelles and craterlike micelles formed by grafted Y-shaped molecules and their reversible reorganization in selective solvents. The Y-shaped molecules have two incompatible polymer chains (polystyrene and poly(tert-butyl acrylate)) attached to a func…
Hyperbranched polymers have received significant attention due to their unique combination of low viscosity, excellent solubility, and facile synthesis. This paper describes an efficient approach to hyperbranched poly(aryl ester)s via the polycondensation of A 2 and B 3 monomers. A dilute bisphenol A (A 2 ) solution w…
The ground- and excited-state properties of a series of meso -tetraphenylporphyrin (H 2 TPP) diacids, [H 4 TPP](X) 2 (X = F, Cl, Br, I), ad hoc synthesized and characterized by 1 H NMR, RLS, and UV−vis spectroscopies, have been studied theoretically using density functional theory (DFT) and time-dependent density func…
Geometric disassembly of dendritic structures was realized by a cascade cleavage reaction triggered by an initially stimulated group at the dendrimer core. Release of an exponential number of dendrimer fragments was a result of the branching nature of the cleavage pathway. Evidence for the completion of the disassembl…
Ordered arrays of Au, Ni, and Si nanorings have been fabricated using Ar + sputter redeposition of material in a porous alumina mask. Typical ring dimensions are 50 nm inner diameter and 10−15 nm wall thickness with heights ranging from 50 to 200 nm. Ring composition was confirmed by electron microscopy. Ring diameter…
A novel synthetic approach to a series of bulky triarylamines substituted by various electron-withdrawing groups and forming amorphous materials is presented. Under vacuum evaporation, thin films with high optical quality are obtained and exhibit spontaneous second-order nonlinear optical activity. This unprecedented…