Hierarchical Meso-/macroporous Metal/Oxide Organophosphonate Hybrid Materials: Synthesis, Characterization And Properties

Chemically designed inorganic-organic hybrid materials have attracted much attention because of the combination of properties due to the inorganic and the organic components. The hybrid materials would display full functions by making a large quantity of fine pores inside the materials. This dissertation shall focus on the synthesis of metal phosphonate and metal oxide/phosphonate hybrid materials with hierarchical meso-/macroporous structures for multifunctional applications in photocatalysis and adsorption.Organic-inorganic hybrid materials of mesoporous titania-tetraphosphonate and titania-pentaphosphonate that formed by the assembly of nanoparticles in a crystalline anatase phase were synthesized by using claw molecules of ethylene diamine tetra(methylene phosphonic acid) and diethylene triamine penta(methylene phosphonic acid) as organophosphorus coupling molecules, respectively, and a nanostructured material of titania-diphosphonate (Ti-HEDP) that possesses a hierarchical macroporous structure composed of mesostructured Ti-HEDP nanorods was prepared with the use of precursor tetrabutyl titanate and 1-hydroxy ethylidene-1,1-diphosphonic acid (HEDP). The organically bridged phosphonate groups were homogeneously incorporated in the network of these nanostructured/porous solid, which exhibited high photocatalytic activity in photodecomposition of dye molecules, and large capacity of selective adsorption of heavy metal ions, making them promising adsorbents and photocatalysts for practical applications including wastewater cleanup.Hierarchically meso-/macroporous titanium tetraphosphonate materials with intraframework ethylenediamine groups were thus synthesized by a simple surfactant-free process with the use of sodium salt of ethylene diamine tetra(methylene phosphonic acid) and titanium tetrabutoxide precursors under a very wide pH range from pH = 3 to 13. Besides the macroporous structure of 100 - 300 nm in size, a wormhole-like mesostructure was in the macropore surface layers of the framework and a mesocellular foam structure in the core part of the macroporous walls, rendering an unusual hierarchical structure of titanium phosphonates, with the integrity of the organophosphonate groups in the macro-/mesoporous solid, which exhibited not only high photocatalytic activity under UV-light irradiation, but also large capacity for heavy metal ion adsorption with a preference sequence of Cd²⁺ < Cu²⁺ < Pb²⁺ and effective regeneration ability.Furthermore, a three-dimensionally ordered macroporous titanium phosphonate material was synthesized by an inverse opals method using 1-hydroxy ethylidene-1,1-diphosphonic acid, and theβ-cyclodextrin-added derivative with hydroxy ethylidene groups inside the frameworks was also performed, having morphology modification and catalytic and adsorptive ability improvement for potential applications as photocatalysts and adsorbents for wastewater cleanup.Alternatively hierarchical meso-/macroporous structure of hybrid aluminum phosphonate (AlPPh) materials were synthesized by using amino tri(methylene phosphonic acid) and bis(hexamethylenetriamine)-penta(methylenephosphonic acid), in the presence and absence of triblock copolymer F127. All the samples possess a uniform macroporous (500 - 2000 nm) structure of mesoporous (4-5 nm) framework. The prepared AlPPh materials were used as multifunctional adsorbents for the efficient removal of heavy metal ions (e.g. Cu²⁺) and the adsorption of proteins (e.g. lysozyme). The differences between the metal ion and lysozyme adsorption were mainly caused by the natures of inorganic ions and proteins and the interactions between the adsorbents and adsorbates.Additionally, a novel nanomanufacturing method was developed for the mass-production of aligned metallic microwires and nanowires by drawing glass tubes that contain appropriate filling materials in powder or rod form. This method combines fiber drawing method with advanced filling materials, thus providing not only desired functionality, but also excellent controls over the aspect ratio, diameter, length and interwire spacing of micro/nanowires. This method could be applied to almost any solid materials for large-scale manufacturing as long as a matching glass could be found, and provides new hierarchically ordered materials at low-cost for a range of applications.