Lynn Walker

Towards systematic design of complex soft materials through interfacial processing

Lynn M. Walker
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh PA

Abstract: Systems involving deformable interfaces between immiscible fluids offer a significant challenge for materials design and processing.   Static interfacial/surface tension is often the only parameter considered in the design of systems with fluid-fluid interfaces.   In foams, emulsions, blends, sprays, droplet-based microfluidic devices and many other applications, the dynamic nature of surface active species and deformation of interfaces requires a more detailed characterization of the interfacial transport, dynamic interfacial properties and interfacial structure.  Macroscopic properties and the ability to tune and control phenomena requires an improved understanding of the time-dependent properties of the interfacial tension and interfacial mechanics.  We have developed tools and approaches to quantify the impact of surface active species on interfacial behavior.  Surfactant-nanoparticle complexes, polymer-surfactant aggregates and proteins show the potential of interfacial processing in controlling interfacial properties.  The use of sequential adsorption, differences in transport timescales and variability in reversibility of different species allows interfaces to be engineered.  This talk will provide the motivation to use microscale interfaces for efficient analysis of complex interfacial phenomena and how that relates to the material properties of interface-dominated materials.

Bio: Lynn M. Walker is a Professor of Chemical Engineering and both Chemistry (by courtesy) and Materials Science & Engineering (by courtesy) at Carnegie Mellon University. She holds a B.S. degree from the University of New Hampshire and a Ph.D. from the University of Delaware, both in chemical engineering.  She was an NSF International Postdoctoral Fellow at the Katholieke Universiteit in Leuven, Belgium before joining CMU in 1997. She has held visiting faculty positions at the Polymer IRC in Leeds, UK, and in Chemical Engineering at UCSB, and held the Piercy Visiting Professorship at the University of Minnesota. Her research focuses on quantifying the coupling between flow behavior and flow-induced microstructure in complex fluids.  Current research focuses in two directions: quantifying the influence of flow on self-assembled nanostructures and controlling transport to complex fluid-fluid interfaces. She has twice been recognized for teaching by receiving the Kun Li Award for Excellence in Education from the Department of Chemical Engineering at CMU, is the 2016 recipient of the Lazarus Award for Mentoring from CMU and the 2015 WIC Mentorship Excellence Award from AIChE.  She recently took the role of Perspectives Editor for AIChE Journal, served as Editor-in-Chief of Rheologica Acta and serves on the editorial boards of the Journal of Rheology, and Journal of Non-Newtonian Fluid Mechanics.  She is a fellow of the American Institute of Chemical Engineers, the Society of Rheology, and the American Physical Society (DSOFT).