Materials Literature
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Abstract A novel synthetic procedure for the preparation of poly(oxadiazole)s was developed with nucleophilic substitution of α,ω‐alkanediols with oxadiazole‐activated bisfluoride. Seven poly(oxadiazole)s were successfully prepared by the solution polymerization of 2,5‐bis(4‐fluorophenyl)‐1,3,4‐oxadiazole and various…
Abstract A series of new thermotropic main‐chain liquid crystalline copolyesters were prepared by polycondensation of 2,6‐naphthalenedicarbonyl chloride, 4,4′‐thiodiphenol, and α,ω‐alkanediols ( n = 4–10) in diphenyl ether at 200°C. Thermal transition behaviors of these copolyesters were investigated by differential s…
The graft copolymerization of methyl methacrylate onto mercaptochitin and some properties of the resulting graft copolymers have been studied. Methyl methacrylate was efficiently graft copolymerized onto mercaptochitin in dimethyl sulfoxide, and the grafting percentage reached 1300% under appropriate conditions. Altho…
Methacrylate derivatives bearing β-D-glucopyranoside and β-D-galactopyranoside residues are synthesised by glycosylation of 2-hydroxyethyl methacrylate (HEMA) with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide and 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide, respectively. β-Selectivity in the glycosylation…
Reduction of an excess of arsenic with a solution of sodium in liquid ammonia yields the thermally unstable title compound [Na(NH3)5]2As(4).3NH3, which contains isolated square-planar As4(2-) ions with a mean As-As bond length of 2,345 A.
Coordination to a Zn(II) center of chelating π-delocalized nitrogen donor ligands such as 5-X-1,10-phenanthrolines (X = OMe, NMe 2, trans- CH CHC 6 H 4 - 4‘ - NMe 2, trans,trans -(CH CH) 2 C 6 H 4 - 4‘ - NMe 2 ) produces a significant enhancement of their quadratic hyperpolarizability measured either by the EFISH tech…
Abstract Interpenetrating networks (IPNs) of polybutadiene‐based polyurethane (PU) and poly(methyl methacrylate) (PMMA) were synthesized. The effect of the incorporation of 2% glycidyl methacrylate (GMA) and 2‐hydroxyethyl methacrylate (2‐HEMA) on the thermal, mechanical, and morphological properties of IPNs was inves…
Abstract Blends of polycarbonate (PC) and poly(acrylonitrile‐ co ‐butadiene‐ co ‐styrene) (ABS) with different compositions are characterized by means of dynamic mechanical measurements. The samples show phase separation. The shift in the temperatures of the main dynamic mechanical relaxation shown by the blend with r…
γ orthorhombic isotactic polypropylene transcrystallinity nucleated on aramid fibers under high pressure was investigated by synchrotron X-ray diffraction and by scanning electron microscopy. It was determined that the c axes of the lamellae (the growth axes) are distributed radially about the fiber and that the lamel…
We use molecular dynamics simulations to model realistic silica-based sol−gel solutions containing water, the simplest alcohols (MeOH and EtOH), the simplest silica alkoxides (Si(OMe) 4 and Si(OEt) 4 ), and small silica clusters (Si(OH) 4, Si 2 O(OH) 6, and Si 3 O 3 (OH) 6 ), at ambient conditions. This work builds on…
A simple and reproducible single phase preparation of 2.5 nm silver nanoclusters is described using silver benzoate along with triethylamine (TEA) and dodecanethiol (DDT); these spontaneously self-assemble to a two-dimensional array whereas in the absence of thiol only polydispersed nanoclusters are obtained.
The cluster compound Au55(PPh3)12Cl6 has been reanalyzed by photoelectron spectroscopy giving direct evidence for a nonmetallic behavior of the individual Au clusters as long as their ligand shell remains intact. The exposure to x-rays during the measurements is found to partly decompose the shell by removal of the ch…
The thermal recovery behavior of fluorinated single-walled carbon nanotubes has been systematically examined by UV−vis−near-IR absorption spectroscopy, IR absorption spectroscopy and electric resistance measurements under different annealing temperatures. The decrease in the IR intensity of C−F stretch bands centered…
A new approach to the preparation of large palladium nanoparticles with diameters between 25 and 100 nm is presented. In this approach PdCl42− ions are reduced on the surface of performed 12-nm-diameter gold “seeds” by the introduction of ascorbic acid. The resultant particles exhibit improved monodispersity relative…
Reaction of 5,10,15,20-tetraphenyl-2-aza-21-carbaporphyrinatonickel(II) with dihalomethanes in the presence of a proton scavenger gives a 2,21'-CH2-linked dimer of Ni(II) inverted porphyrins with the yield reaching 90% and its 2,2'-linked isomer as a minor product.
Three types of random copolymers with 94 mol % (R)-3-hydroxybutyric acid (3HB) and 6 mol % (R)-3-hydroxyalkanoic acids with different side-chain lengths, (R)-3-hydroxypentanoic acid (3HV), (R)-3-hydroxyhexanoic acid (3HHx), and medium-chain-length (R)-3-hydroxyalkanoic acids (mcl-3HA, C8-C12), were prepared by biologi…
Organic−inorganic polymer hybrids were prepared by an in-situ method. In the presence of ruthenium salt, the cross-linking reaction of bipyridyl-containing polymer was carried out together with the sol−gel reaction of tetramethoxysilane. This methodology includes the simultaneous formation of silica gel and organic ge…
In this study, polypyrrole (PPy) films were electrochemically deposited on gold substrates roughened by a triangular-wave oxidation−reduction cycle (ORC) in an aqueous solution containing 0.1 N KCl. The results indicate that the intensity of surface-enhanced Raman scattering (SERS) of PPy significantly depends on the…
Electron beam lithography on Langmuir−Blodgett films of alkanethiol-capped gold nanoparticles is shown to be a viable strategy to define nanometer scale structures of such particles. Sub-50 nm wide “nanowires”, the thickness of which is controlled at the single particle level, are created with e-beam doses in the mC/c…
Thin films of vanadium dioxide have been deposited on glass by low pressure metal-organic chemical vapour deposition using the β-diketonate complex, vanadyl acetylacetonate, as the precursor. It is found that nearly monophasic, monoclinic VO2(M) films are formed in the narrow temperature range 475–520 °C, films formed…