Modeling Solute Diffusion in Polymeric Membranes for Gas Separations

Columbia University, New York NY

Investigators

Abstract

Nontechnical Summary This award supports a computational driven approach to develop the design principles of polymeric membranes which present an efficient solution for emergent technologies, such as CO2 capture and natural gas purification. While there have been many advances made in this field, most of them have been performed empirically - consequently, it is reasonable to state that there is little quantitative understanding of the molecular principles that control the separation ability of these membrane materials. Driven by these facts, here we propose to critically delineate the underpinnings of these separation technologies using a suite of molecular simulation methods on a variety of models, going from those directly relevant to experiment to ones that focus in extracting universal principles. The successful completion of the proposed research could result in the development of computational tools and fundamental understanding that could facilitate robust design methodologies for polymeric membranes specific to current and emerging clean energy technologies. Highly permeable, but selective, polymeric materials will enable efficient, low-cost, CO2 separations. These research efforts will be coupled to a suite of education and outreach activities. Driven by the group's recent success in recruiting high school and undergraduate students for summer research, the proposal is to continue to recruit students from historically minority schools, as well as undergraduate and high school students from the greater New York City area. The PI's group has previously worked with several women and minority high school students who have subsequently decided to study science and engineering in college. The proposal is to continue this pipeline approach to recruit and retain underrepresented minorities in science and engineering fields. Technical Summary This award supports a computationally-driven approach to develop the design principles of polymeric materials for membrane applications - materials which present an efficient solution for emergent technologies, such as CO2 capture and natural gas purification. These polymeric materials have to be capable of selective and efficient transport of gases. The main objective of the proposed research is to critically delineate factors controlling separation processes in polymeric membranes by using a suite of molecular simulation methods, going from those directly relevant to experiment to ones that focus in extracting universal principles. The PI's approach is focused on the local, vibrational dynamics of a dense glassy polymer, as characterized by the long-time plateau value of the mean-squared displacement of the frozen matrix. This is postulated to define the appropriate dynamic "free-volume" metric. The PI's group will establish: if this dynamic "free-volume" metric is universal, if it has experimental backing, and how it is affected by chain stiffness, chain packing, solute-solvent interactions, the solute size and shape, the glassiness of the matrix, and the presence of heterogeneities such as nanoparticles. This will be achieved through a fundamental, simulation-based understanding of this relationship. The successful completion of the proposed research could result in the development of computational tools and fundamental understanding that could facilitate design methodologies for polymeric and polymer-hybrid membranes specific to current and emerging clean energy technologies. Highly permeable, but selective, polymeric materials will enable efficient, low-cost, CO2 separations. These research efforts will be coupled to a suite of education and outreach activities. Driven by the PI's group recent success in recruiting high school and undergraduate students for summer research, the proposal is to continue recruitment of students from historically minority schools, as well as undergraduate and high school students from the greater New York City area. The PI's group has previously worked with several women and minority high school students who have subsequently decided to study science and engineering in college. The proposal is to continue this pipeline approach to recruit and retain underrepresented minorities in science and engineering fields.