Chemical Engineering Seminar
Lilian Hsiao is an assistant professor of Chemical and Biomolecular Engineering at North Carolina State University. She received her B.S. in Chemical Engineering from the University of Wisconsin-Madison in 2008 and her Ph.D. in Chemical Engineering from the University of Michigan in 2014. She received the Rackham Predoctoral Fellowship for her work with Michael Solomon on the microstructure of colloidal suspensions in flowing systems. Her postdoctoral training at the Massachusetts Institute of Technology with Patrick Doyle was on colloidal nanoemulsions and 3D printing. She started her tenure-track position at NC State in 2016. Her group is recognized for advancing the fields of suspension rheology and soft haptic materials, recently through the Camille Dreyfus Teacher-Scholar Award, Sloan Research Fellowship, ACS Unilever Award for Outstanding Young Investigator in Soft Matter, NSF CAREER award, and AAAS Mason Award.
There is an increasing need to engineer interfacial friction in technologies as diverse as soft robotics, virtual reality, and consumer products. The animal kingdom provides many examples of soft surfaces that can effectively control friction, even in extreme environments where high shear rates and complex fluids are found at the interface. This talk focuses on the solid and fluid mechanics principles that can explain frictional tribology when different fluids and heterogeneous patterns influence the interfacial mechanics of sliding. The first part of the talk focuses on colloidal suspension rheology when particle roughness is present. Rough colloids have interesting linear viscoelasticity and shear thickening physics that arise from rotational constraints between particles. Direct visualization from confocal rheometry, combined with mode coupling and hydrodynamic models, provide a compelling explanation based on excluded volume length scales. The second part of the talk investigates various ways of modifying the friction between elastomer and hydrogel surfaces, including the use of slip additives such as erucamide, incorporation of pattern geometry that mimic the finger ridges of humans and robots, and using dense colloidal suspensions as the continuum lubricating fluid. The long-term vision is to create new frontiers in haptic science through the interfacial design of colloidal and polymeric materials.