Molecular orientation and mechanical anisotropy of polypropylene sheet containing N,N′‐dicyclohexyl‐2,6‐naphthalenedicarboxamide

Effect of mixing and processing conditions at T‐die extrusion on the structure and mechanical properties is studied for isotactic polypropylene (PP) containing a small amount of β‐form nucleating agent, N,N′‐dicyclohexyl‐2,6‐naphthalenedicarboxamide. It is found that trigonal β crystals are predominantly formed in the extruded samples containing the nucleating agent irrespective of the mixing and processing conditions, leading to the marked mechanical toughness. On the contrary, the molecular orientation is significantly affected by the mixing and processing conditions. In particular, it should be noted that PP molecules in the extruded sheet which was mixed at high temperature (260 °C) and extruded at low temperature (200 °C) orient perpendicular to the applied flow direction. As a result, the sheet shows anomalous mechanical anisotropy. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 424–433, 2009     

Preparation and properties of covalently cross-linked sulfonated copolyimide membranes containing benzimidazole groups

A series of sulfonated copolyimides containing benzimidazole groups (SPIs) were synthesized by random copolymerization of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 2-(4-aminophenyl)-5-aminobenzimidazole (APABI), 4,4′-diaminodiphenyl ether-2,2′-disulfonic acid (ODADS) and 9,9-bis(4-aminophenyl)fluorene (BAPF) in m-cresol in the presence of benzoic acid and triethylamine at 180 °C for 20 h. Membranes with good mechanical properties were prepared by solution cast method. Proton exchange treatment resulted in ionic cross-linking and the membranes were further covalently cross-linked by treating them in polyphosphoric acid (PPA) at 180 °C for 6 h. The covalently cross-linked membranes displayed slightly lower ion exchange capacities (IECs) and proton conductivities than the corresponding covalently uncross-linked ones because small part of the sulfonic acid groups had been consumed during the cross-linking process. Fenton’s test (3% H₂O₂ + 3 ppm FeSO₄, 80 °C) revealed that benzimidazole groups played an important role in the radical oxidative stability of the membranes, while the cooperative effect of benzimidazole groups and covalent cross-linking led to much more significant enhancements in the radical oxidative stability of the membranes than each alone. The membrane 4 (ODADS/APABI/BAPF = 2/1/1, by mol), for example, after covalent cross-linking could maintain membrane form within 8 h measurement, which was much longer than that (3 h) before covalent cross-linking under the same conditions. The membrane 5 (ODADS/BAPF = 3/1, by mol) without benzimidazole groups, however, after covalent cross-linking started to break into pieces after 85 min measurement, which was only slightly longer than that (60 min) before cross-linking under the same conditions.     

Ion-pair chromatography of dianionic species by dionium reagents

Summary Dionium cations, polymethylenebis(tributylphosphonium)s (BuC_nBPs), were used as ion-pair reagents for ion-pair chromatography of dianionic species, such as maleate, fumarate, phthalates, and naphthalenedisulfonates. The longer the length of methylene chain connecting the two phosphonium cationic ceterns within BuC_nBP, the larger was the retention of these dianionic species. The dionium reagents had a higher retention ability compared to conventional monoonium reagents, and enabled a higher resolution among the dianionic species of structural isomers. The extraction behavior of the dianionic species in a loctanol/water system was also investigated. The retention behavior by the use of BuC_nBP was discussed in comparison with the extraction behavior.     

Reaction of 2-propargylphenylcarbamates with diphenyliodonium salts via Meyer-Schuster rearrangement

The syntheses of 2,3-dihydro-4-quinolones from 2-propargylphenylcarbamates by one-pot tandem process that involves Meyer-Schuster rearrangement or arylative Meyer-Schuster rearrangement/Michael addition of carbamate nitrogen to the resulting vinyl ketones have been developed. Phenylcarbamates tethering tertiary propargyl alcohols underwent arylative Meyer-Schuster rearrangement/Friedel-Crafts alkylation to produce 2,3-dihydroindenones.     

Dependency of ligand free energy landscapes on charge parameters and solvent models

We performed replica-exchange molecular dynamics (REMD) simulations of six ligands to examine the dependency of their free energy landscapes on charge parameters and solvent models. Six different charge parameter sets for each ligand were first generated by RESP and AM1-BCC methods using three different conformations independently. RESP charges showed some conformational dependency. On the other hand, AM1-BCC charges did not show conformational dependency and well reproduced the overall trend of RESP charges. The free energy landscapes obtained from the REMD simulations of ligands in vacuum, Generalized-Born (GB), and TIP3P solutions were then analyzed. We found that even small charge differences can produce qualitatively different landscapes in vacuum condition, but the differences tend to be much smaller under GB and TIP3P conditions. The simulations in the GB model well reproduced the landscapes in the TIP3P model using only a fraction of the computational cost. The protein-bound ligand conformations were rarely the global minimum states, but similar conformations were found to exist in aqueous solution without proteins in regions close to the global minimum, local minimum or intermediate states.     

Complex alloys containing double-Mackay clusters and (Sb(1-δ)Zn(δ))(24) snub cubes filled with highly disordered zinc aggregates: synthesis, structures, and physical properties of ruthenium zinc antimonides

A series of cluster-based ruthenium zinc antimonides with a large unit cell were obtained. Their structures were solved by the single crystal X-ray diffraction methods. They crystallize in the cubic space group of Fm3?c (No. 226) with cell dimensions of 25.098(3), 24.355(3), 24.307(3), and 24.376(3) ? for Ru(26)Sb(24)Zn(67) (CA), Ru(13)Sb(12)Zn(83.4) (CB), Ru(13)Sb(6.29)Zn(91.56) (CC), and Ru(13)Sb(17.1)Zn(74.8) (CD), respectively. By all indications, compounds CA and CB are two phases showing pronounced distinctions regarding compositions, lattice parameters, thermal and transport properties, but they are not members of an extended solid solution. Compounds CB, CC, and CD are three members of a same solid solution. Topologically, these four compounds contain face-centered cubic packing of double-Mackay type clusters and (Sb(1-δ)Zn(δ))(24) snub cubes filled with highly disordered zinc aggregates, with or without glue atoms between them. Both phases CA and CB are diamagnetic. There is a difference of ～170 K between their thermally stable temperatures. CA exhibits rather low thermal conductivity with the value of ～0.9 W m(-1) K(-1) at room temperature, which is about one-third that of CB. The electrical resistivity of CB is almost temperature independent. The Seebeck coefficient of CB is small and negative, while that of CA exhibits a complicated temperature dependence and undergoes a transition from p- to n-type conduction around room temperature.     

tert-Butoxide-mediated arylation of benzene with aryl halides in the presence of a catalytic 1,10-phenanthroline derivative

Sodium tert-butoxide mediates the coupling of aryl halides with benzene derivatives without the aid of transition metal catalysts but with a catalytic 1,10-phenanthroline derivative.     

Mesostructured organosilica with a 9-mesityl-10-methylacridinium bridging unit: photoinduced charge separation in the organosilica framework

Polycondensation of 9-mesityl-10-methylacridinium-bridged organosilane in the presence of a nonionic surfactant yielded a mesostructured organosilica solid with a functional framework that exhibited long-lived photoinduced charge separation.     

Optical interconnection between different spatial modes using double phase conjugate mirror with polarization alignment system

We propose a fundamental interconnection method using a polarization alignment system for waveguides having different spatial modes. In addition, as an example for the verification of the fundamental operation, we demonstrate an interconnection between a photonic crystal fiber and a laser that have obviously different spatial modes. The polarization alignment system operates synergistically with a self-written waveguide formed with a double phaseconjugate mirror. This technique enables us to interconnect a photonic crystal fiber with a laser source without complicated and time-consuming optical alignment. In this method, although it is not necessary to perform an external control for interconnection, the waveguide most suitable for connection is formed autonomously in a Sn₂P₂S₆:Sb crystal developed for this purpose. There was a marked reduction in the polarization dependence of coupling efficiency, compared with that observed using a stand-alone double phase-conjugate mirror.