CAREER: Medium-Range Order in Polymeric Phosphate Glasses: Effects of Atomic-Scale Structures on Macroscopic Properties

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9733350 Otaigbe This Faculty Early Career Development project will investigate one of the most fundamental and general questions regarding the properties of amorphous materials: namely, what is the relationship between the structural characteristics of disordered materials and the various physical processes used to produce the amorphous material. Specifically, the project will examine the changes in polymeric phosphate glass structure caused by variations in composition and evolved by melt processing. It will correlate these structural changes in novel durable polymeric phosphate glasses with the rheology, durability to water, and resistance to crystallization. The research objectives will be accomplished using an interdisciplinary approach that integrates aspects of materials science, rheology, solid-state chemistry and physics, and process engineering to explore the effects of controlled shear flow on both the short-range and the intermediate-range order structure of the glasses produced. The macroscopic glass structure will be studied by various spectroscopy, microscopy, high performance liquid chromatography, and calorimetry techniques; it will then be linked to its microscopic origin through X-ray diffraction experiments. This work will correlate melt-processing conditions (such as shear distortion, temperature, and shear rate) with the ultimate rheological behavior of the glass. The results will be compared to reported structural models for phosphate glasses. This project will evolve into a major education and research capability at Iowa State University that will be facilitated through collaborations with international leaders in phosphate glass research. In addition, students in the Materials Science and Engineering (MSE) Department will be provided with a relevant, and practice-oriented education that is attractive to industry. This objective will be accomplished by (a) providing research experiences for graduate and undergraduate students in MSE; (b) demonstrating to students the synergistic effect of interdisciplinary research in solving fundamental problems using innovative, computer-based instructional modules; (c) developing graduate student internship opportunities with industry by leveraging both the human and the equipment resources of the industrial collaborators; (d) developing simple practical materials science demonstration kits for high school science students and other distant education teaching aids; (e) developing cooperative student learning groups, and (f) incorporating research findings into the principal investigator's courses. %%% Understanding the dependencies of chemical durability and resistance to crystallization tendencies on both the composition and the melt-processing conditions of phosphate glasses will enhance the use of phosphate glasses in applications such as glass-to-metal seals for high expansion metal applications, flame retardants, biomaterials, storage materials for nuclear wastes, optics, phosphorescent/fluorescent materials, scintillators, and load-bearing organic/inorganic composites. In addition, students in the Materials Science and Engineering (MSE) Department at Iowa State University will be provided with a relevant, and practice-oriented education that is attractive to industry. ***