Development and application of novel metal carboxylate glass matrices
A range of new mixed metal carboxylate ((M(O2CR)n) glasses has been prepared. Typically, Mn+ = alkali metals, alkaline earth metals, Zn2+, Pb2+, Sn2+, Co2+ and Cu2+. R increases from CH3 to C7H15 and higher. The alkyl chain can also be branched or aromatic. The properties of these glasses are affected by both the metal cations and carboxylate anions. Densities range from 1.2 to 2.7 g cm-3 and refractive indices from 1.4 to 1.6. Transparency has been shown to extend from 250 to 1400 nm. The carboxylate mixtures could be maintained in the molten state, at temperatures ranging from 100-200°C for prolonged periods without decomposition. Glass transition temperatures have been determined; these generally extended from 30°C up to 60°C. The melts were excellent solvents for a wide range of organic compounds. These dissolved in the carboxylate melts with no appreciable decomposition. The melts could then be quenched to give monolithic glass matrices. By choosing specifically designed organic compounds, the glasses have potential application for photochromism, electrochromism and non-linear optics. Investigation of the solubility of the glasses in water indicated the dependence on cation combination and chain length of the carboxylate ion. These investigations were made to explore the use of the glasses as host media for the release of agrochemical and other compounds with biological activity. It has been shown that Culex quinquefasciatus gives a positive ovipositional response to pheromone that is released from doped glasses over an extended time period. An investigation of the glass structure and the environment it provides for guest materials was undertaken using selected analyses. The structures of zinc carboxylates were determined by X-ray crystallography to provide information pertinent to the nature of the coordination of zinc in these glasses. Organotin compounds were dissolved in carboxylate glasses and studied by 119Sn NMR and Mossbauer spectroscopy. Anion exchange reactions readily occurred in the melts; there was also evidence of Sn-C bond cleavage with certain species. The potential of using Mossbauer spectroscopy as a probe into the glass "structure" is discussed.