Chemical Engineering Seminar

Abstract: Understanding and harnessing interactions between materials under confinement provides design strategies for coatings, recycling, batteries, and biomaterials. This presentation will cover two research topics from our group. First, we will discuss our efforts to connect intermolecular forces to macroscopic mechanical response to better understand how soft materials make contact and adhere under dynamic conditions. We will show how the lifetime of cooperative hydrogen bonds can be extracted from macroscopic crack propagation. Then we will discuss the role of the interplay between the electrical double layer and lubrication in confined geometries. Specifically, we will discuss our work to characterize the structure of the electrical double layer in highly concentrated aqueous electrolytes. We highlight how hydrodynamics alters the apparent structure of the electrical double layer (or vice versa) and combine our findings with wide-angle X-ray scattering to characterize the bulk structure of the electrolytes. We see that the adsorbed ion lead to apparent slip and also how confinement alters the fluid viscosity. This work contributes to understanding the structure and charge-neutralization mechanism under static and dynamic conditions in this class of electrolytes and the interfacial behavior of mixed-electrolyte systems encountered in electrochemistry and biology.

Bio: Joelle Frechette received her PhD from Princeton University in Chemical Engineering and Materials Science studying surface forces and adhesion in electrochemical environment. She joined Johns Hopkins University in 2006 and moved to UC Berkeley in 2021. She was awarded the NSF CAREER award, the 3M untenured faculty award, the ONR Young Investigator award, and was elected as a Fellow of the American Chemical Society in 2017. Her research interests include: adhesion in fluid environments, particles at fluid interfaces, and surface force measurements.