http://smartech.gatech.edu/handle/1853/25137 Seminar Program for Graduate Students in the School of Chemical and Biomolecular Engineering Search the Channel search http://smartech.gatech.edu/simple-search http://smartech.gatech.edu/handle/1853/30402 Title: Volume-Phase Transitions in Surface-Tethered Networks and Implications for Swelling Instabilities <br/> <br/>Authors: Toomey, Ryan <br/> <br/>Abstract: The overall thrust of our research program is to develop responsive structures without the need for complex circuitry or bulky instrumentation. Our approach is to use polymers that undergo volume-shape changes in response to an external stimulus. The stimulus alters the balance of hydration forces within the polymer network, resulting in changes to the macroscopic properties. In this talk, I will discuss the role of intermolecular forces and how they can be harnessed to control volume-phase transitions in polymer networks. I will also discuss techniques for fabricating surface-confined networks, including soft lithography and photo-lithography strategies, as well as the effect of surface-confinement on the response characteristics of the polymers. Finally, it will be shown how instabilities can be induced in hydrogel microstructures to facilitate reconfigurable topographies with sensing and actuation integrated at the material level. Such reconfigurable surfaces can have important implications for variable adhesion, self-cleaning materials, and separations. <br/> <br/>Description: Presented on September 16, 2009 from 4-5 pm in room G011 of the Molecular Science and Engineering Building. http://smartech.gatech.edu/handle/1853/30139 Title: Functionalized Nanostructured Tri-Block Copolymer Ionomers for Separations and Fuel Cell Applications <br/> <br/>Authors: Rosado, David Suleiman <br/> <br/>Abstract: Proton exchange membranes (PEMs), commonly used in direct methanol fuel cells (DMFC), are typically limited by either high methanol permeability (also known as the cross-over limitation) or low proton conductivity. A potential alternative to this problem is to use thermoplastic elastomers (TPE) with rubbery and glassy thermodynamically immiscible microphases. The glassy segment is often composed of polystyrene, which can be sulfonated to high ion exchange capacities (IEC), and thus creates ion containing polymers or ionomers. Linear poly-styreneisobutylene- styrene (SIBS) and both, linear and branched poly-styrene-isoprene-styrene (SIS), were sulfonated and functionalized with different cations (size and electronegativity). Controlling the degree of sulfonation and the functionalization allowed for selective membranes that could be used for applications such as fuel cells, gas sensors, and permselective separations. In addition, supercritical fluid processing allowed for additional morphological changes, especially with perfluorinated membranes. This presentation will review some of the critical materials characterization results including elemental analysis (EA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and Fourier transform infrared spectroscopy (FT-IR). The kinetic and transport properties will also be discussed for the development of separation processes and catalytic nanochannel reactor arrays for fuel cell applications. <br/> <br/>Description: Presented on September 9, 2009 from 4-5 pm in room G011 of the Molecular Science and Engineering Building. http://smartech.gatech.edu/handle/1853/27921 Title: Integration of Production Planning and Scheduling in the Chemical Industry <br/> <br/>Authors: Maravelias, Christos <br/> <br/>Abstract: To remain competitive in today’s environment, chemical companies must adopt an integrated view across all their operations and use advanced planning methods to achieve enterprise-wide optimality. At the production level, it is necessary to simultaneously consider medium-term (planning) and short-term (scheduling) decisions. Despite recent advances in computer hardware and optimization software, current methods are insufficient to address real-world instances of this integrated problem. Three approaches to this integrated problem are discussed. First, a novel formulation for the “generalized” lot-sizing problem is presented. This formulation accounts for process characteristics that are common in the chemical industry but are not addressed by existing approaches. Second, a number of theoretical results for discrete-time formulations are developed, enabling us to formulate problems that can be solved very effectively. Third, we present how detailed scheduling models can be used off-line to obtain an approximation of feasible production levels and an underestimation of production cost. Finally, we present how these methods can be used to address large-scale integrated planning-scheduling problems. <br/> <br/>Description: Presented on April 15, 2009 from 4-5 pm in room G011 of the Molecular Science and Engineering Building. http://smartech.gatech.edu/handle/1853/27918 Title: Control of Microfluidic Devices <br/> <br/>Authors: Burns, Mark A. <br/> <br/>Abstract: The field of microfluidics is uniquely poised to significantly impact the biomedical sciences through the miniaturization and massive parallelization of biochemical assays. For example, future advances in microfluidics could revolutionize disease diagnosis, drug discovery, and pathogen detection. In our work, we focus on components and integrated systems that can be used in health-related biochemical analysis. Construction of such systems is currently relatively easy; there are a large number of published “lab on a chip” systems constructed from a variety of substrates using different actuation, sensing, and control components. However, there are still relatively few microfluidic diagnostic systems commercially available. Although there are many reasons, one possible explanation for this scarcity is the complex interconnect requirements of many pneumatically actuated analysis chips. In an attempt to overcome this disadvantage, we have developed microfluidic components and systems that strive to reduce the required number of pneumatic interconnects. For instance, a single pressure input can be sent to multiple temperature-regulated venturis, each of which is capable of generating a unique pressure signal. In addition to electronically controlled components, pneumatically controlled components can be used such as pneumatic logic gates and decoders. These and other components will be discussed in terms of integrated biochemical analysis systems. <br/> <br/>Description: Presented on April 22, 2009 from 4-5 pm in room G011 of the Molecular Science and Engineering Building.