“Interfacial Friction of Soft Materials”
The need to engineer interfacial friction is increasingly important in technologies as diverse as soft robotics and consumer products. The first part of the talk focuses on the role of particle roughness in the rheology, structure, and dynamics of dense colloidal suspensions. Rough colloids at maximum packing, unlike hard sphere systems, retain strong rheological memory and shear thickening properties that could be leveraged to create impact resistant soft materials. We analyze these unusual rheological phenomena using direct visualization from confocal rheometry, glass transition and hydrodynamic models, and the reduced mobility of interlocked particles. The second part of the talk focuses on our group’s recent work on bioinspired soft materials. We investigate the effect of material chemistry as well as pattern geometry on the sliding friction of elastomer and hydrogel surfaces separated by very thin fluid layers. Using a semi-analytical lubrication and elasticity model that accounts for the compression and bending of patterns, it is possible to accurately predict the interfacial friction experienced by humans and robot fingers sliding across wet textured materials. Our long-term vision is to create new frontiers in haptic science through the physico-chemical design of colloidal and polymeric materials.
Lilian Hsiao is an assistant professor of Chemical and Biomolecular Engineering at North Carolina State University. She received her Bachelor of Science in Chemical Engineering from the University of Wisconsin-Madison in 2008 and her PhD 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, most 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.