Rosa Espinosa
University of Illinois

Interfaces, Confinement, Assembly, and Soft Matter

Location: EB1 Room 1011

Friday, February 3rd 2017 - 11:00 am

It is a challenging but fruitful task to bring materials and surface science together to tailor the properties of solid-liquid interfaces and solvated soft films at the molecular and nanoscale in order to control the resulting macroscopic behavior. As examples for this approach, I will present recent efforts in two separate areas of my research involving (1) ionic liquids and (2) hydrogels/lipid bilayers.

The energy stored in a supercapacitor relies on the formation of an electrical double layer in the electrode nanopores to counterbalance the surface charge. To achieve high energy densities, electrolytes with a wide electrochemical window and a small electrical double layer thickness are required; ionic liquids have been proposed as potential electrolytes for energy storage due to their electrochemical stability and high charge density. In this context, I will share our recent work on the electrified graphene-ionic liquid interface. A fundamental study of the surface interactions reveals the characteristics of an "extended" Stern layer and a relatively thick diffuse layer and how the stored charge changes with applied potential. Design strategies to improve performance in terms of patterning graphene and modifying the molecular composition of the ionic liquid are proposed.

The complexity of living cell membranes has inspired the design of a biointerface, a hydrogel-supported lipid bilayer. Swollen hydrogels represent a class of biologically significant materials because their soft, hydrated, fluid permeable polymeric network structures resemble many biological tissues and organisms. A combination of techniques is used to fundamentally understand the behavior of the lipid bilayer supported by this soft cushion, which demonstrates that the bilayer interface can mimic the biomechanical behavior of cell membranes, inter alia. The soft cushion beneath the bilayer increases bendability and stability of the bilayer, while the lipids still retain their characteristic diffusivity.

The outlook for these research topics is exciting. We are aware of the global challenges in energy and health and we possess tools and creativity. A short-term extension of the presented research is also discussed.

Rosa Espinosa-Marzal holds a MEng. Degree in Mechanical Engineering (Universidad Politecnica de Valencia, Spain), and a Ph.D. in engineering/materials (Hamburg University of Technology, Germany, 2004). Dr. Espinosa-Marzal joined the faculty of the Department of Civil and Environmental Engineering at the University of Illinois at Urbana-Champaign as Associate Professor in September 2013, where she is involved in research and teaching in several areas of surface science and technology. Prior to joining Illinois, Dr. Espinosa-Marzal was a Senior Scientist in the Materials Science Department at ETH Zurich (Switzerland), and a research fellow at Princeton University. Dr. Espinosa-Marzal is the recipient of a research grant to promote highly qualified young researchers awarded by the German Research Foundation (DFG), and of a DAAD fellowship (German Academic Exchange Service) for her graduate studies. In 2016, Dr. Espinosa-Marzal was appointed CAS Associate (Center for Advanced Study) at the University of Illinois.

North Carolina State University