last update: March 28, 2001
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STC-ERSP Program Details Principal Investigator: S. L. Wallen Project Title: NMR Studies of Structure and Dynamics of CO2 Systems (Former Prog #4) Research Plan Connectivity Outreach Components Additional Comments Requested Budget Allocation - Year 1 Plans for Additional Funding Research Plan Overall objectives Wallen proposes to structurally and dynamically characterize species covalently bound and adsorbed to interfaces utilizing sum-frequency generation (SFG), NMR and Raman spectroscopy. The combination of these techniques allow surfaces to be interrogated by both locally surface specific and macroscopic averaging techniques that together offer a comprehensive understanding of the surface structure and its relation to dynamics including transport, partitioning and intermolecular relaxation. The primary objective is to utilize this two-prong approach to investigate the effects of changing pressure, temperature and CO2 solution composition on interfacial systems. Relation to overall objectives of the Center An important component of the Thrust Area A: Interfacial and Colloid Science in Compressible Media will be to elucidate the effects of compressible solution conditions on interfacial dynamic processes and structure. Research objectives described above will allow an understanding of the molecular level details necessary to make rational decisions and predictions regarding the design of molecular systems for areas that are dominated by interfacial chemistry. These systems include analytical separations and extraction, cleaning and coating processes. Approach and Year 1-Year 5 timelines Years 1-2: Set-up sum-frequency generation system. Develop a multi-channel, sum-frequency spectroscopic technique for use in compressible CO2 systems. Develop protocols for preparing samples with specific covalent attachments to fused silica surfaces. Begin to perform experiments on C18 and C8 alkanes attached to a silica surface to investigate conformational changes of the chains in air and exposed to CO2 under a variety of conditions of temperature and pressure. Expand these studies to surface attached molecules containing -CF2 and -CF3 groups. Perform analogous experiments utilizing surface-enhanced Raman spectroscopy. Develop protocols for preparing high-surface area sol-gel glasses with surfaces modified as in the SFG experiments. Measure reorientational correlation times of CO2 solutions in contact with these surfaces by Raman and NMR. Years 2-3: Expand the previous studies to new surface active molecules developed by center researchers. Develop methodologies to apply the SFG technique to the examination of kinetics of deposition and removal of species utilizing CO2. Design a system allowing SFG studies at the liquid-liquid interface in CO2-H2O binary systems. Develop methodologies to use the SFG system to investigate reorientational dynamics through Kerr Effect spectroscopy. Years 4-5: Develop methodologies to investigate additional types of surfaces including additional dielectrics as well as metal film surfaces. Thrust area of this proposal Thrust Area A: Interfacial and Colloid Science in Compressible Media Connectivity Collaborators, multi-institutional, multi-disciplinary components We anticipate the interaction with a numbers of groups in this thrust area. Particularly groups involved in the synthesis of novel polymers and surfactants for use in CO2 (DeSimone-UNC-CH) as well as groups with well-established engineering programs related to micellization and polymers dissolved in CO2 (Johnston-UT-Austin and Fulton-PNNL). Related work in other thrust areas As surfaces are ubiquitous in all heterogeneous processes we believe that there are opportunities for collaboration between this project and those involved in Thrust Area D (Chemistry and Catalysis), particularly, those interested in surface immobilization of metallic or enzymatic catalysts. In addtion, certain aspects of the work will provide useful information to Thrust Area B (Molecular Thermodynamics and Computer Simulations) through a detailed description of the thermodynamic dependence of molecular structure and dynamics. Sharing of resources (students, supplies, equipment, etc.) The post-doctoral associate and student assigned to this project will interact with researchers who are interested in utilizing the SFG system to investigate surface structure. We expect that there will be many novel molecular architectures resulting from Center synthesis activities that are surface active and are excited about utilizing these with the Raman and SFG equipment. Outreach Components Suggested K-12 Outreach Ideas Wallen and the funded student are available to discuss light and its use as an analytical tool. Previous demonstrations have been done for elementary school students but could include teacher programs. The Wallen group has recently hosted a high school teacher in the lab as part of the NSF sponsored PREP program and we hope to continue this in connection with Center research activites. Additional Comments Our NMR and vibrational spectroscopic techniques can be available to any researcher who is interested in collaborating on dynamic and structural characterization in CO2 systems. Requested Budget Allocation - Year 1 Personnel salaries
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