last update: March 28, 2001
|
STC-ERSP Program Details Principal Investigator: M. L. Berkowitz Project Title: Molecular Dynamics Simulations of Multi-component Systems in CO2 (#6) Phone/Fax: (919)-962-1218 (919)-962-2388 E-mail: maxb@unc.edu Research Plan Connectivity Outreach Components Requested Budget Allocation - Year 1 Plans for Additional Funding Research Plan Overall objectives The aim of the project is to develop a comprehensive understanding of the phase equilibria, structure and interfacial properties of multi-component systems in CO2. We plan to use computer simulation methods to systematically explore properties of pure CO2 and properties of binary and ternary mixtures. The binary mixtures we plan to study include CO2 plus small molecules, including polar molecules (water, ethanol), non-polar molecules (e.g. methane, ethane, hexane and their fluorinated counterparts). We also plan to study binary mixtures of CO2 plus medium-to-large chain-like molecules whose segmental constituents are members of subclasses listed above. Finally, we plan to study ternary mixtures of CO2, water and multi-component organic molecules of interest. Relation to overall objectives of the Center The ability to design surfactants for interfaces between CO2 and liquids or solids offers new opportunities in material science, separation science, polymer science and environmental science. Little is known about the interfacial properties between liquid or supercritical CO2 and solid surfaces , water or organic phases with and without surfactants. The key objective of the project is to determine the balance between CO2-philic and CO2-phobic segments of a surfactant to achieve a desired degree of adsorption at the interface. Understanding of how the molecular structure, the intermolecular interactions and dynamics influence the thermodynamics and kinetics of mixtures in CO2 that can be gained from computer simulations is a prerequisite to the rational design and synthesis of surfactants. Approach and Year 1-Year 5 timelines Years 1-2: Perform simulations on pure CO2 at different densities and study the behavior of the dielectric constant as a function of density. Fine tune the potential (if needed). Perform simulations of binary mixtures of CO2 and hexane, CO2 and perfluorohexane using united atom and explicit atom potential models in order to understand the role of electrostatic interactions in specificity of fluoroalkane/CO2 interactions. Calculate free energies of transformation of fluoroalkanes into alkanes to understand entropic vs energetic contributions. Years 2-3: Extend the simulations from simple alkanes/CO2 mixtures to more complicated binary mixtures including mixtures of surfactants such as FOA and FPE in CO2. Years 2-5: Perform simulations on RM in CO2, study their structure and dynamics. Using the methodology developed to study rare events calculate rates for transfer of material at the interfaces. Thrust area of this proposalThrust area B: Thermodynamics and Simulations Connectivity Collaborators, multi-institutional, multi-disciplinary components These simulations will be performed in partnerships with numerous groups. With the group of K. Gubbins we plan to work on the refinement of the potential for pure CO2. The work on mixtures (binary and tertiary) is planned to be done in collaboration with the group of M. Rubinstein. Related work in other thrust areas The researchers in Thrust Area A (Interfacial and Colloidal Science in Compressible Media) will use information obtained from the simulation and theory to rationally design new surfactants. The researchers in Thrust Area C (Rate Processes) will be using these surfactants in the study of novel separations that use surfactants and will investigate the utility of surfactants in modifying foaming processes. The researchers in Thrust Area D (Chemistry and Catalysis) will be using these surfactants to stabilize polymeric colloids and to emulsify extremophilic enzymes in CO2. Sharing of resources (students, supplies, equipment, etc.) The students and post-doctoral fellows will share computer facilities. They will also work closely with the PIs identified above. Outreach Components Suggested K-12 Outreach Ideas Berkowitz and people from his group will be available in teacher workshops to present topics such as "How computers help us in the design of new materials". Requested Budget Allocation - Year 1 Personnel salaries
Plans for Additional Funding Funding agencies/programs and planned dates of submission: 1). NSF: Structure and dynamics of surfactants at liquid/liquid interfaces in Spring 2000. 2). NIH: Molecular Dynamics simulations of phospholipid membranes in Spring 2000. Return to top. |
|
