Materials Literature
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The secondary relaxation of poly(2-vinylpyridine) (PVPy) in a complex and blends with poly(4-vinylphenol) (PVPh) was studied by broadband dielectric spectroscopy. The polymer complex can be obtained by mixing PVPh and PVPy in methyl ethyl ketone as a result of the very strong hydrogen bonding between two polymers, and…
Morphology formation and deformation behaviour of asymmetric styrene/butadiene triblock copolymers (total polystyrene (PS) content ∼70%) consisting of PS outer blocks held apart by a styrene-co-butadiene random copolymer block (PS-co-PB) each were investigated. The techniques used were differential scanning calorimetr…
Abstract In this study, tetra isopropyl ortho titanate (TTIP) and polycaprolactone (PCL) were chosen as the ceramic precursor and the continuous phase, respectively, for the preparation of novel nanocomposites by using an in situ sol‐gel process. In addition, acrylic acid grafted polycaprolactone (PCL‐ g ‐AA) was inve…
Abnormal upfield shifts for the external azulene protons are seen in the 1H NMR spectra on oxidation of azuliporphyrins with copper(II) acetate to give highly distorted copper(II) complexes (see structure, brown Cu, blue N, red O, green H). These undergo demetalation with 10 % trifluoroacetic acid/chloroform to give u…
The molecular chain and lamellar crystal orientation in ultrathin films (thickness < 100 nm) of poly-(di-n-hexylsilane) (PDHS) on silicon wafer substrates have been investigated by using transmission electronic microscopy, wide-angle X-ray diffraction, atomic force microscopy, and UV absorption spectroscopy. PDHS show…
Abstract Lactide polymerization using zirconium(IV) acetylacetonate [Zr(acac) 4 ] as an initiator was investigated. In the reaction between Zr(acac) 4 and the monomer molecule, lactide deprotonation and the release of acetylacetone occurred. The structures of the obtained complexes were analyzed with high‐resolution N…
Abstract This investigation deals with the thermal or thermooxidative degradation behavior of three engineering polymers [e.g., poly(ethylene terephthalate) (PET), poly(ether sulfone) (PES), and poly(ether ether ketone) (PEEK)] by using thermogravimetry‐coupled mass spectrometry (TG‐MS) analysis. The experiments were…
The use of aqueous emulsions as the media when conducting cross-coupling reactions, instead of homogeneous solutions, produces covalently cross-linked conjugated polymer particles (see picture). The size of the spherical particles can easily be tuned over a wide range (mm to nm) by modification of the reaction conditi…
Abstract Grafted inorganic nanoparticles can greatly improve the mechanical performance of polymers. To examine the effects of the interfacial characteristics generated by the grafting polymer bonded to nanoparticle surfaces, we chemically grafted nano‐silica with different polymers and then melt‐mixed it with polypro…
The alignment of thin films of symmetric diblock copolymer of polystyrene and poly(methyl methacrylate), PS- b -PMMA, in an electric field was studied as a function of film thickness and interfacial energy using small-angle neutron scattering and transmission electron microscopy. There is a competition between the app…
The first theoretical evidence for tetracoordinate planar nonmetals hosted at the centers of square hydrometal complexes M4H4X (M=Cu, Ni; X=B, C, N, O; see picture) has been obtained by ab initio calculations. These predictions may open a new branch of chemistry of nonmetal-centered hydrometals with potential applicat…
Shell shock: Shell cross-linked (SCL) micelles (3) are prepared by polyelectrolyte complexation by using a micelle-forming cationic ABC triblock copolymer (1) in conjunction with an anionic diblock copolymer cross-linker (2). This ionic cross-linking approach involves polymeric reagents that form physical complexes ra…
The Ge/sub 2/Sb/sub 2/Te/sub 5/ (GST) thin film is well known to play a critical role in PRAM (Phase Change Random Access Memory). Through device simulation, we found that high-resistive GST is indispensable to minimize the writing current of PRAM. For the first time, we tried to increase the GST resistivity by doping…
We report the first observation of oscillations of the electromagnetic field in an optical superlattice based on porous silicon. These oscillations are an optical equivalent of well-known electronic Bloch oscillations in crystals. Elementary cells of our structure are composed by microcavities whose coupling gives ris…
Previous theoretical investigations of colossal magnetoresistance (CMR) materials explain this effect using a "clustered" state with preformed ferromagnetic islands that rapidly align their moments with increasing external magnetic fields. While qualitatively successful, explicit calculations indicate drastically diff…
Using a novel approach to calculate optical properties of strongly correlated systems, we address the old question of the physical origin of the alpha to gamma transition in Ce. We find that the Kondo collapse model describes the optical data better than the Mott transition picture. Our results compare well with exist…
Extensive electronic structure calculations are performed to obtain the stable geometries of metals like Al, Ga and In on the Si(001) surface at 0.5 ML and 1 ML coverages. Our results coupled with previous theoretical findings explain the recent experimental data in a comprehensive fashion. At low coverages, as shown…
We report a uniaxial pressure-dependence of magnetism in layered perovskite strontium ruthenate Sr3Ru2O7. By applying a relatively small uniaxial pressure, greater than 0.1 GPa normal to the RuO2 layer, ferromagnetic ordering manifests below 80 K from the enhanced-paramagnet. Magnetization at 1 kOe and 2 K becomes 100…
The volume of tantalum versus pressure has been accurately measured up to 101 GPa by single-crystal x-ray diffraction, with helium as pressure transmitting medium. Slight deviation from previous static determinations is observed. Discrepancy with reduced shock-wave and ultrasonic data supports recent doubts about the…
Using effective-field theory with correlations, we investigate the effects of interfacial pseudo-spin coupling fluctuations on the susceptibility and polarization of ferroelectric superlattices within the framework of transverse Ising model. It is found that the interfacial coupling fluctuations increase the susceptib…