Transition-Metal Coordination in Polymer Blends

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Several metal-containing polymer blends which form coordination complexes are the focus of this investigation. The model compounds are low-molecular-weight salts in which the divalent metal centers range from iron to copper in the first row of the d-block, and ruthenium to silver in the second row. The ligand is poly(4- vinylpyridine) or copolymers that contain 4-vinylpyridine repeat units. Thermal analysis via differential scanning calorimetry and polarized optical microscopy will be employed to generate thermodynamic phase diagrams of these binary mixtures. At the molecular level, high-resolution carbon-13 solid-state nuclear magnetic resonance and Fourier transform infrared spectroscopies will be used to probe microenvironmental factors that influence mixing. Natural abundance nitrogen-15 solid-state nuclear magnetic resonance experiments in oversized rotors will provide a direct probe of metal-ligand sigma-bonding that involves the lone pair on nitrogen. The proposed enhancement of miscibility via coordination-type interactions brought about by metal ions is important because most polymer mixtures are not miscible, which limits their usefulness. Any improvement would lead to new structural materials.