Tuesday, 01 October, 2013
"Directing the Surfactant Templating of Oxide Materials for Adsorption, Catalysis and Energy"
The sol-gel method is a room-temperature, chemical route to metal oxide materials. The low temperature of the method enables the incorporation of organic components through weak interactions (ionic and hydrogen bonding) or by covalent attachment, thus allowing self-assembly and interfacial engineering concepts to be utilized to control pore architecture and surface functionality.
In this talk, Rankin will describe ongoing research in which his group explores new ways to use interfacial concepts to control the synthesis of surfactant-templated metal oxide materials. The goal will be to highlight design principles that emerge from a fundamental understanding of the nanoscale processes at play.
He will begin by discussing the tuning of pore architecture in thin metal oxide films prepared by evaporation-driven self-assembly. Coarse-grained Monte Carlo simulations suggest that alignment of micelles normal to interfaces may be induced by weak interactions of both polar and nonpolar components with the interface. This concept will be demonstrated to work to induce orthogonal alignment of close-packed cylindrical arrays of micelles within dip-coated sol-gel films. These films have potential use as components of photovoltaic structures (with titania as n-type semiconductor and an organic p-type semiconductor) and as Lithium ion battery electrodes.
Another ongoing direction in Rankin's group is the use of specific interactions at the micelle surface to induce templating of catalytic and adsorption sites for energy applications. He will discuss two uses of mixed cationic and saccharide-based surfactants for this purpose. The first will be the synthesis of mesoporous materials in which the saccharide surfactant is used not only to template pores, but also to prepare isolated catalytic sites for epoxidation catalysis. The second application will be the imprinting of the surface of silica nanoparticles to prepare molecularly imprinted materials for saccharide separations such as to separate glucose and xylose in a biorefinery process.
Dr. Stephen E. Rankin is currently a professor at the University of Kentucky in the Department of Chemical & Materials Engineering. He earned his BS degree at Carnegie Mellon University and his PhD degree at University of Minnesota, all in chemical engineering. Prior to the University of Kentucky, he worked as a Postdoctoral Appointee at Sandia National Laboratories, a Department of Energy facility, on modeling coupled reaction and drying in ordered and disordered porous inorganic coatings and particles.
Rankin is the co-director of graduate studies in the Department of Chemical & Materials Engineering at the University of Kentucky. He has received numerous awards, including the Gill Professor at the University of Kentucky, NSF CAREER Award for research regarding organic-inorganic hybrid materials, and the US Department of Energy Defense Programs Early Career Scientist and Engineer Award.