Synthesis and characterization of oxide materials: Polymer-layered oxide nanocomposites and crystal growth of lanthanide containing platinates.

摘要

Part I. Polymer-layered oxide nanocomposites Polymer nanocomposites, consisting of nano-sized additives uniformly dispersed in a polymer host matrix, have exhibited substantial enhancements in physical properties relative to the pristine polymers. Research in nanocomposites has shifted towards layered oxides as the preferred additive. The layered structure allows for exfoliation, or separation of layers, which increases the aspect ratio, and subsequently property enhancements.; Polyethylene terephthalate (PET) is a polymer mainly used in packaging materials for food and beverages. PET alone has minimal gas barrier properties. This becomes problematic for beer, wine, and tomato-based products that are sensitive to oxygen or loss of carbon dioxide. Layered oxides, specifically layered silicates, can act as a barrier by providing a more tortuous path for gases to diffuse.; This research project involved the synthesis and exfoliation of layered silicates, hectorite and magadiite, and incorporation into polymer matrices, such as PET and rubber. In addition, covalent organic modifications of the silicates were explored to improve silicate-polymer interactions. Property enhancements of the resulting nanocomposite materials, including gas barrier, were measured. Synthesis and characterization of the nanocomposite materials with an emphasis on gas barrier properties will be discussed in chapters 1-5.; Part II. Crystal growth of lanthanide containing platinates Crystal growth of oxide materials using high temperature solutions has been well established. The zur Loye research group has found molten hydroxides and carbonates to be an effective medium for crystal growth of new oxide crystals containing lanthanide and platinum group metals. La3NaPtO 7 and La4PtO7 crystals were grown from carbonate fluxes, and a K4Ln6Pt2O15 (Ln = La, Pr, Nd, Sm-Gd) series of crystals were grown from hydroxide fluxes. This series resulted in a unique channeled structure type. The crystal growth and structural characterization of these new compounds will be discussed in chapters 6-8.