Preparation and characterization of some organic derivatives of [alpha]-zirconium phosphate /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1990.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | α-Zirconium phosphate possesses a two-dimensional, layered structure similar to clays and clay materials. In this structure, the hydroxyl groups of the phosphates point away from the layers and into the interlayer region (sometimes called the "gallery"). Analogues can be prepared in which the phosphate groups are replaced with either phosphonic acids or phosphoric acid esters. In this way, the hydroxyl groups are replaced with organic pendant groups. The layers are then held apart by these organic groups that are attached to them. Changes in the size and nature of the organic groups alter the physical and chemical properties of the compounds. A compound with a mixture of large and small groups can be prepared from a mixture of acids. The products formed can be a mixture of phases, a solid solution, or a single phase with short range ordering. In the last type of product, adjacent interlayer regions contain only one type of group and, as a result, the single phases possesses the properties of both of the individual phases. These types of compounds could be used to exchange or intercalate different species between the two distinct types of interlayer regions. For example, a "staged" compound was prepared that had both hydrophobic (phenyl groups) and hydrophilic groups (hydroxyl groups). Organic species could be intercalated in the former, while simple cation exchange could be carried out in the latter. In addition, rigid diphosphonic acids can be used to cross-link adjacent layers, holding them a fixed distance apart. The resulting compounds have been called "pillared" compounds and do not swell or disperse in solvents. By replacing some of these pillars with non-cross-linking groups, void spaces on the order of molecular dimensions can be created in the space between the layers. The non-pillaring groups can have functional groups of their own, or functional groups can be added after the mixed compound has been prepared. The mixed compounds generally formed larger particles than the fully-pillared "parent" compound. In spite of their larger particle size, however, the mixed compounds have surface areas that are comparable to the parent compound. These high surface areas reflect the number of accessible, internal spaces in which the adsorbate can condense. The sizes of the pores were distributed over a fairly narrow range, making them useful in applications where a degree of size selectivity is desirable. These materials have potential uses in catalysis, ion exchange, and selective sorption of small molecules. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Chemistry." |
| Physical Description: | xvi, 162 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |