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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 1493-1503 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystals of the trans-octahedral complex Co(4-Vpy)4(NCS)2 on being heated below the melting point decompose with liberation of 4-vinylpyridine (Vpy) and concurrent polymerization of the free monomer. The two reactions have been followed by differential scanning calorimetry, thermogravimetry, and optical microscopy. Polymerization is inhibited by inclusion of hydroquinone during recrystallization of the complex. This has allowed the kinetic analysis of the decomposition and polymerization to be simplified. Isothermal mass-loss determinations under reduced pressure (10-2 torr), at various temperatures in the range 120-160°C, on hydroquinone-inhibited crystals corresponded to the loss of up to three molecules of vinylpyridine per molecule of starting complex. With uninhibited crystals over the same temperature range the total number of ligands lost was approximately two with a marked decrease near 175°C owing to rapid polymerization. Isothermal decomposition curves for inhibited and uninhibited crystals approximated to the Avrami-Erofeev equation. Values of n varied with temperature. Activation energies for decomposition and polymerization for both types of crystal were estimated from Arrhenius plots.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 14 (1976), S. 2819-2830 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structures of the precipitates of free-radical poly(4-vinylpyridine) (Vpy), free-radical poly(2-Vpy) and isotactic poly(2-Vpy) with M(II)Cl2 (M = Co, Ni, Cu, Zn) obtained from solution have been investigated. The polymer compounds are similar to the known crystalline monomeric Vpy complexes and, with one exception, are crosslinked by the metal dichloride. Co(II) and Zn(II) are tetrahedrally coordinated by the polymer, while the Ni(II) and Cu(II) complexes are probably tetrahedral and square-planar, respectively. Because of the constraints of the polymeric ligands the stoichiometries of the complexes are not exactly the same as those of the monomeric Vpy complexes and from one to two Vpy units per metal halide are on average not coordinated. Atactic and isotactic poly(2-Vpy) showed marked differences with regard to coordination of Ni(II). The questions of stereochemistry of the coordinated metal ion, stoichiometry of the complexes, intermolecular versus intramolecular complexation of the polymer chain, and the influence of polymer tacticity on the crystallizability of polymer complexes are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 2561-2574 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A survey of the solid-state polymerizability of 2- and 4-vinylpyridine (Vpy) complexes of divalent cobalt, nickel, copper, and zinc chlorides has been carried out. The influence of metal ion, ligand, coordination stereochemistry, and crystal structure is discussed. The tetrahedral modification of the complex Co(4-Vpy)2Cl2 has been found to undergo a particularly facile thermal polymerization below its melting point to yield high molecular weight poly-4-vinylpyridine. The polymer is shown to be conventional atactic head-to-tail poly-4-vinylpyridine. Thermogravimetric methods and optical microscopy have been used to study the thermal polymerization of single crystals of the complex. Results indicate a diffusion-controlled mechanism in which defective regions in the crystal act as nuclei for the polymerization.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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