CBE Seminar - Nicole Zacharia

Nicole Zacharia

Assistant Professor

Department of Polymer Engineering

The University of Akron

Modulating Supramolecular Interactions in Polyelectrolyte Multilayers

Abstract

Polyelectrolyte multilayers have long been examined as responsive materials based on modulation of the secondary interactions that hold them together. One type of secondary interaction that has been less examined within these assemblies is the metal-ligand coordination bond. The first part of the talk will investigate how incorporating varying metal ions can change the physical properties such as modulus or adhesion. Using different multi-valent ions as well as alkali versus transition metal ions can control these changes in properties. We show the variation of interaction between polyelectrolytes and metal ions using various types of spectroscopy; FTIR, UV-vis, and XPS. In addition to using different types of bonds to make up the polyelectrolyte assemblies, the dynamic nature of the secondary interactions that do hold them together makes it possible for these materials to be responsive to external stimuli. These external stimuli work by changing the strength of these secondary interactions. It is well known that changes in pH or ionic strength in the surrounding environment can create changes in polyelectrolyte multilayer properties, generally by weakening the secondary interactions. Our group, however, has recently been examining the use of organic solvent to change the properties of polyelectrolyte multilayers. Organic solvents dehydrate the multilayers, contracting and densifying the film, as well as stiffening the film. This stimulus then can be used as the basis of creating actuating materials from polyelectrolyte multilayers.  

Bio

Dr. Nicole S. Zacharia received B.S. degrees in mathematics and materials science and engineering from the Massachusetts Institute of Technology in 2001, followed by a Ph.D. in materials science and engineering in 2007 also from MIT. During her PhD she worked under the supervisions of Prof. Paula Hammond and graduated with a focus on polymeric and biomaterials. After time as a postdoc at the University of Toronto working under Prof. Geoffrey Ozin, she became an assistant professor in the materials division of mechanical engineering at Texas A&M in 2009. She is currently an assistant professor of polymer engineering at the University of Akron. She is an NSF CAREER awardee. Her research group focuses on the assembly of polyelectrolytes both in solution and at interfaces