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September 26, 2013

Speaker: Paul A. Charpentier, Western University

Title: Supercritical Fluids- A Unique Methodology for Advanced Materials

Abstract: This talk will give an overview of our research groups recent advances in nanoscience for emerging areas in alternative energy and device fabrication. In particular, the talk will explore the work in our lab using supercritical carbon dioxide (scCO2) as an enabling vehicle for the synthesis of a new generation of nanomaterials and nanodevices due to its low viscosity, high diffusivity, and “zero” surface tension. Our synthesis methodology utilizes sol-gel and polymer chemistry, while being able to combine these into a unique one-pot procedure. This methodology has allowed the formation of well defined nanostructures of metal oxides including TiO2 and modified titania with ZrO2, Fe, N and other dopants by this template-free scalable method, along with their polymer nancomposites. In addition, scCO2 has been an invaluable solvent for producing advanced materials from carbonaceous substances such as graphenes, carbon aerogels and a variety of nanocrystals such as quantum dots (QDs). The formation of these nano structures has been monitored by in situ FTIR in which the titania alkoxides were found to form hexamer crystal structures that react and self-assemble by sol-gel and supramolecular chemistry through the acetate ligands. The directed self-assembly and interactions between graphene and TiO2 were comprehensively studied using Vienna ab-initio Simulation Package (VASP) based Density Functional Theory (DFT). This talk will examine the structure-function relationship of these materials for several applications in dye sensitized solar cells (DSSCs), light-selective nanofilms for greenhouse films, self-cleaning polymer coatings, and biomedical devices, where being able to control the nanostructure was found to provide unique functional materials with superior properties.