Application of Polymer Kinetics and controlled Self-Assembly in multi-dimension Nanomaterial Synthesis
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The Symposium provides undergraduates from all academic disciplines with an opportunity to share their research with the university community and other guests through conference-style oral presentations. The Symposium represents part of a larger effort of Iowa State University to enhance, support, and celebrate undergraduate research activity.
Though coordinated by the University Honors Program, all undergraduate students are eligible and encouraged to participate in the Symposium. Undergraduates conducting research but not yet ready to present their work are encouraged to attend the Symposium to learn about the presentation process and students not currently involved in research are encouraged to attend the Symposium to learn about the broad range of undergraduate research activities that are taking place at ISU.
The first Symposium was held in April 2007. The 39 students who presented research and their mentors collectively represented all of ISU's Colleges: Agriculture and Life Sciences, Business, Design, Engineering, Human Sciences, Liberal Arts and Sciences, Veterinary Medicine, and the Graduate College. The event has grown to regularly include more than 100 students presenting on topics that span the broad range of disciplines studied at ISU.
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Interest in nanomaterials has risen in the recent past, primarily due to the unique properties of materials at the nanoscale. There are two main approaches to nanomaterial synthesis, viz; top-down (fragmentation) and bottom-up (self-assembly driven). Coupled approaches, however, have potential to give unprecedented control over material synthesis. We employed a top-down approach to increasing etch rate, and bottom-up approach to synthesize nano-sized beams, sheets, and cubes. Onedimensional coordination polymers were grown at steady-state conditions — achieved through solubility-limited etching of liquid metal alloys. Stoichiometric control of substitution around the central metal atom leads to asymmetry in substitution patterns, which in turn influences the self-assembly of these 1D polymers. Therefore, three separate growth rates exist; K1 (polymerization), K2 (x-y plane assembly), K3 (x-z plane assembly). These growth rates can be engineered to affect the self-assembly process to construct various nanomaterials including cubes (K1≈K2≈K3), sheets (K1≈K2>>>K3), and beams (K1>>>K2>K3). All materials were characterized by scanning/tunneling electron microscopy (SEM, TEM), x-ray photoelectron spectroscopy (XPS), and x-ray diffraction.