last update: March 21, 2001
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STC-ERSP Program Details Principal Investigator: Keith Johnston Project Title: Interfacial Tension Measurements Between Liquids/Solids and CO2 (Former Prog #2) Research Plan Connectivity Outreach Components Additional Comments Requested Budget Allocation - Year 1 Plans for Additional Funding Research Plan Overall objectives Little is known about static or dynamic interfacial properties between a CO2 phase and a liquid or solid phase or how these properties are influenced by surfactants. A sound fundamental understanding of the relationship between interfacial properties and surfactant structure is of vital importance for the rational design and synthesis of surfactants, especially given the unusual solvent properties of CO2. The interfacial tension will be measured with pendant (liquid drop), sessile (liquid drop interacting with a solid surface) and captive (liquid drop emanating from a tube interacting with a solid surface) drops or bubbles. These techniques will be used to measure interfacial tensions at the liquid-CO2 interface and contact angles between an aqueous, organic or liquid CO2 phase with a solid inorganic or organic phase. Relation to overall objectives of the Center The ability to design surfactants for interfaces between CO2 and liquids or solids offers new opportunities in materials science, protein/polymer chemistry, separation science and environmental science. Little is known about the static or dynamic interfacial properties between liquid or supercritical CO2 and solid surfaces, water, or organic phases, with or without surfactants. A key objective will be to determine how to balance the "CO2-philic" and "CO2-phobic" (anchor) segments of a surfactant to achieve the desired degree of adsorption at a given interface. Approach and Year 1-Year 5 timelines Years 1-2: Investigate interfacial tensions at CO2water interface for various surfactant structures. Measure contact angles for water on various surfaces with added surfactant in the presence of CO2. Years 2-3: Utilize interfacial tension measurements to identify surfactants and conditions for studies of microemulsions in CO2. Modify apparatus for high temperatures to study CO2-water and CO2-polymer interfaces with and without surfactants. Study dynamic interfacial tension. Years 2-5: Study surfactants for lowering interfacial tension of polymer-CO2 interfaces. Study polymer-polymer interfaces. Relate results to theoretical models of interfacial properties and structure. Provide suggestions for synthesis of new surfactants. Thrust area of this proposal Thrust Area A: Interfacial and Colloid Science in Compressible Media Connectivity Collaborators, multi-institutional, multi-disciplinary components Measurements of surfactant adsorption from the interfacial tension will be complementary to those with spectroscopic techniques by Wallen (Area A). Interfacial properties will be useful to Carbonell in studying thin-films by free meniscus experiments (Carbonell, Thrust Area A). Measurements of interfacial tension at the polymer-CO2 interface are useful to Khan's study of foaming (Area C). Interfacial tensions and surfactant adsorption will be calculated theoretically by gradient and self-consistent field models and computer simulation in a collaboration between Hall, Sanchez, Rossky and Johnston.(Thrust Area B: Molecular Thermodynamics and Computer Simulations). Static and dynamic interfacial properties including surfactant adsorption will play a major role in many aspects of the center including formation and stabilization of micelles (DeSimone et al., Area A), microemulsions (Webber, Area A; Kelly and Carbonell, Area C), and latexes (DeSimone, Area D). These microemulsions and emulsions are of interest to Tumas, Area D, in catalytic processes. Additional examples include wetting and de-wetting (Wallen, Grant, Roberts, Carbonell: Area C) which influence cleaning of surfaces as well as thin film formation(DeSimone and Carbonell, Area C). Dynamic interfacial tension measurements complement studies of surfactant diffusion and interfacial kinetics. Related work in other thrust areas Listed in above section Sharing of resources (students, supplies, equipment, etc.) The interfacial tension apparatuses will be available for systems of interest to researchers throughout the center. The measurements of this project will be useful to DeSimone and Webber in surfactant synthesis; the converse is also very important. Outreach Components Suggested K-12 Outreach Ideas Johnston and the student will be available in teacher workshops to demonstrate experiments to illustrate interfacial properties and to explain how surfactants can be developed for CO2. Additional Comments Please contact me if you have systems you would like to study. Requested Budget Allocation - Year 1 Personnel salaries
Plans for Additional Funding Funding agencies/programs and planned dates of submission: DOE: Effect of Surfactant Conformation on Colloidal Interactions in Inorganic Dispersions and Micro Emulsions in Carbon Dioxide in Fall 1999. (with Korgel) Return to top. |
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