ChBE Seminar - Phase Change and Partitioning in Nanoliter Droplets

Armour College of Engineering's Chemical and Biological Engineering Department will host a seminar featuring Professor of Chemical Engineering at Carnegie Mellon University, Shelley L. Anna. She will present her lecture, Phase Change and Partitioning in Nanoliter Droplets.

Abstract

Synthesis of new materials often relies on processes such as phase change, contacting of multiple fluid and solid phases, and transport of colloidal particles from one phase to another. Determining the relevant kinetic and transport parameters needed to design and optimize such processes can be challenging, especially when there are multiple interacting components. Using nanoliter volume droplets, we show two different approaches to accessing critical process parameters by systematically varying composition and observing transport and phase change in complex fluids as functions of time. An important application is the purification of single wall carbon nanotubes, which can be sensitively separated by species metallicity, chirality, and size in aqueous two phase polymer mixtures combined with specific surfactants. Despite the promise of this passive and low energy separation method, the lack of data relating the partition coefficient of a carbon nanotube species to polymer-surfactant mixture composition presents a major roadblock to its application at large scale. Using monodisperse, nanoliter droplet slugs containing polymer-surfactant-nanotube mixtures, the partition coefficient of the nanotubes is mapped as a function of nanotube species and matrix composition. Separately, nanoliter droplets are also used to quantify the conditions for phase separation of the polymer-surfactant mixtures, as well as the ultra-low interfacial tension between the immiscible polymer phases, which is critical to preventing the adsorption and degradation of partitioning particles. In these examples, we see that small volume droplets can be used to interrogate complex fluid processes with high composition and time resolution.

Speaker Bio

Shelley L. Anna is Professor of Chemical Engineering at Carnegie Mellon University. She holds affiliated appointments in Mechanical Engineering and Physics. Prior to joining Carnegie Mellon in 2003, Dr. Anna received her B.S. in Physics from Carnegie Mellon, and an M.S. and Ph.D. in Engineering Science from Harvard University in 2000. She worked as Senior Research Engineer at Solutia Inc., and then completed a postdoctoral fellowship at Harvard University. Dr. Anna’s research interests include multiphase microfluidics, interfacial rheology, and microscale transport phenomena. Dr. Anna is the recipient of a 2005 NSF CAREER award, the 2006 George Tallman Ladd Research Award from the College of Engineering at Carnegie Mellon, a 2012 Honorable Mention for the Carnegie Science Award for Emerging Female Scientist, and the Russel V. Trader Career Faculty Fellowship in Mechanical Engineering in 2011. Dr. Anna is a Fellow of the American Physical Society.