Tunable Porosities and Shapes of Fullerene‐Like Spheres

The formation of reversible switchable nanostructures monitored by solution and solid‐state methods is still a challenge in supramolecular chemistry. By a comprehensive solid state and solution study we demonstrate the potential of the fivefold symmetrical building block of pentaphosphaferrocene in combination with Cu^I halides to switch between spheres of different porosity and shape. With increasing amount of CuX, the structures of the formed supramolecules change from incomplete to complete spherically shaped fullerene‐like assemblies possessing an I_h‐C₈₀ topology at one side and to a tetrahedral‐structured aggregate at the other. In the solid state, the formed nano‐sized aggregates reach an outer diameter of 3.14 and 3.56 nm, respectively. This feature is used to reversibly encapsulate and release guest molecules in solution.     

Dielectric relaxation and ionic transport in poly(ethylene carbonate)‐based electrolytes

To study the ion‐conductive and dielectric properties of polymer electrolytes based on poly(ethylene carbonate) (PEC) with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), the complex permittivity and conductivity were measured using broadband dielectric spectroscopy. The temperature dependence of the relaxation frequency and ionic conductivity for PEC‐LiTFSI electrolytes (1 – 200 mol%) indicates that the segmental motion of PEC chains decreases with the addition of just 1 mol% of Li salt and increases with increasing concentration above 10 mol%. According to the Walden rule for PEC‐based electrolytes, the value of deviation from the reference line increased, and the fragility and decoupling exponents decreased with increasing salt concentration. These results indicate that there are large numbers of ion pairs and aggregated ions, which imply low ionicity and reduced fragility in highly concentrated PEC‐based electrolytes. Copyright © 2016 John Wiley & Sons, Ltd.     

Stereospecific polymerization of methacrylonitrile. I. Characterization of crystalline polymethacrylonitrile

Methacrylonitrile (MAN) was polymerized with diethylmagnesium. Acetone-insoluble portions of the polymers are found to be crystalline. Highly crystalline portions can be isolated by further extraction of the acetone-insoluble parts with dimethylformamide (DMF). A film of DMF-insoluble fraction can be oriented uniaxially by hot-press rolling. The crystalline PMAN is insoluble in the usual solvents for amorphous PMAN because of their crystallinity and is easily soluble in CF₃COOH or Cl₂CHCOOH. The viscosity–molecular weight relationship was determined in Cl₂CHCOOH at 30°C. as [η] = 3.24 × 10^?3M^0.520. We found several crystalline bands in the infrared spectra, for example, at 1192 and 885 cm.^?1. Formation of the carbonyl group in the polymer is discussed, and it is concluded that it may be formed by the hydrolysis of conjugated cyclic imine or hydrolysis of the nitrile group in the polymer to acid amide.     

Amorphous polyacrylonitrile: Synthesis and characterization

Amorphous polyacrylonitrile was successfully synthesized with bis(pentamethyleneimino)magnesium in heptane at 70°C. The amorphousness of the polymer increased with rising polymerization temperature and was favored by the nonpolar solvent. The polymer showed regular head-to-tail sequences which were confirmed by converting the polymer into polyacrylic acid and polymethylacrylate. The amorphous PAN produced a broad x-ray diagram with a maximum at 2θ = 16.1° and a less intense halo at 2θ = 27.5°. This pattern did not change after heat treatment. The synthesis of amorphous PAN strongly supports Imai's hypothesis that polyacrylonitrile consists of paracrystalline and amorphous phases. The amorphous PAN also tends to support Minami's assignment of the two absorptions in the temperature dependence of the dynamic loss tangent; the absorption at the lower temperature (110°C) is due to molecular motions in the paracrystalline phase and the absorption at the higher temperature (160°C) is attributed to the molecular motions in the amorphous region.     

Harzbasen bei der Harzbildung aus Phenol und Formaldehyd

Zusammenfassung Ausgehend von der Formulierung der Alkoholbildung aus Phenol und Formaldehyd als Ionenreaktion, der Ionenbildung der Alkohole in Anlehnung an K.Hultzsch und der Bildung von Harzbasen als wesentlicher Bestandteile des Natrium-Phenol-Resols werden im Gegensatz zu den aus Kettenmolekülen der Mehrkern-Phenole bestehenden Novolaken die Resole als Kationen einseitig zu „Igel-Molekülen“ zusammengefa\ter Alkohole des Phenols oder von Mehrkern-Phenolen dargestellt. Beim Natrium-Phenol-Resol bildet die endst?ndige Alkoholgruppe in o-Stellung zum Phenol-Hydroxyl wegen der Wasserstoff brücke komplexe Kationen um Natrium als Zentralatom, in denen 6 Phenolmoleküle oder Kettenmoleküle der Mehrkernphenole 6-strahlig zusammengefa\t sind. Beim Ammoniak-Phenol-Resol kann statt einer Fassung zum komplexen Kation die Bindung der Phenole, die endst?ndige Phenole in Kettenmolekülen sein k?nnen, über Methylenbrücken an je ein Stickstoffatom im N-CH₂-ring oder gemeinsam an ein dreifach funktionelles Stickstoffatom erwartet werden. Die Darstellung der Harzbildung ist nicht nur in übereinstimmung mit den bisher bekannten Ergebnissen der Forschung, sie vermag auch bisher nicht erkl?rliche Beobachtungen zu deuten. Sie begründet den kugeligen Bau der Moleküle in den Resolen, sie erkl?rt die Reaktion von vornehmlich p-Oxybenzylalkohol in saurem Medium, die Bildung von vornehmlich o-Oxybenzylalkohol mit steigendem Gehalt an Natriumhydroxyd, das Fehlen von o-o′-Dioxy-diphenylmethan in technischen Harzen, das überwiegen von p-p′-über o-p′-Dioxy-diphenyl-methan in sauer hergestellten Harzen und die optimale Harzbildung bei mittlerem Hydroxyd-Gehalt und begründet Beobachtungen bei der praktischen Anwendung von Resolen, wie aus dem Beispiel der Verleimung von Metall mit Natrium-Phenol-Resol hervorgeht.