SPEAKER: Benjamin L. Doughty (Oak Ridge National Laboratory)
TITLE:
Self-Assembly and Solvation at Liquid/Liquid Interfaces: From Solvent Extraction to Soft-Matter Electronics
ABSTRACT: Liquid/liquid (L/L) interfaces host a range of phenomena essential to fields as diverse as chemical separations, materials synthesis, and even neuromorphic computing applications. Despite the importance and utility of L/L interfaces, there is a surprising lack of insight into how even model species assemble into functional units there. This limited understanding arises predominantly from challenges in selectively probing the few species at the molecular monolayer without being overwhelmed by signals from the neighboring bulk phases. Here, we discuss our efforts aimed at understanding the mechanisms underlying the assembly of molecular extractants and ionic oligomers at oil/aqueous interfaces using surface specific vibrational sum frequency generation spectroscopy. We show how the structure and packing of amphiphilic tails in the oil phase can be tracked in time and tuned via H-bonding and ion pairing interactions in the adjacent aqueous phase despite no direct interaction. Comparing results obtained from L/L interfaces to those measured at air/aqueous interfaces reveals dramatic differences in assembly behavior and the structures that are formed at equilibrium. These differences arise from key, but often overlooked, solvation interactions taking place on the non-polar side of the interface. These results hint at how self-assembly and function can be controlled through seemingly innocuous yet synergistic interactions taking place on both sides of the phase boundary, while highlighting how physical insight obtained from one interface cannot necessarily be transferred to another.
About the speaker: Ben received his Ph.D. in 2010 from the University of California, Berkeley where he worked under Stephen R. Leone studying ultrafast electronic dynamics in atoms and small molecules using femtosecond soft X-ray/VUV light sources. From there, he joined the group of Kenneth B. Eisenthal at Columbia University where, as a postdoc, he developed new approaches to probe reaction kinetics, equilibrium structure, and binding affinities of biological molecules at microparticle interfaces. In 2013 Ben joined ORNL as a Wigner fellow and has since become a full R&D staff member. In 2018 Ben was awarded the Department of Energy's Office of Science Early Career Research Program award in Separations Science. His current research focuses on understanding chemistry and self-assembly at interfaces for ion separations, soft matter electronics, rare-earth element beneficiation, direct air capture of CO2 and developing nonlinear optical imaging tools to understand living plant-microbe systems.
LINK: https://uchicago.zoom.us/j/94220080385?pwd=b0VpcUFUOFNDT0pITk5WeTg4YjAwZz09
Meeting ID: 942 2008 0385
Password: 013444