Cain Department of Chemical Engineering SEMINAR

“Structure and Rheology of Polyelectrolyte Complex Coacervates.”

Amanda Marciel
University of Chicago

Polyelectrolyte complexes are highly tunable materials that span from low-viscosity liquids (coacervates) to high-modulus solids with high water content, making them attractive as surface coating, membrane purification and bioadhesive materials.  However, most of their properties and their effects with salt, pH, polymer ratio and temperature have only been qualitatively described.  Here, we present a scattering investigation of the structure and chain conformations, and rheological properties of polyelectrolyte complex (PEC) coacervates comprising model polyelectrolytes.  Systematic studies using small-angle X-ray scattering (SAXS) of the structure and chain behavior in liquid PEC coacervates revealed a physical description of these materials as strongly screened semidilute solutions of polyelectrolyte solutions upon addition of salt, the solids were largely unaffected by it.  The dynamics of the chains in PEC coacervates, explored by rheology measurements, revealed a Maxwell liquid-like behavior, excellent superposition of the dynamic moduli data was achieved by a time-salt superposition, although with the shift factors varying more strongly than previously reported with increasing salt concentration.

Tuesday, January 16, 2018

1202 Patrick Taylor Hall

Coffee will be served at 10:30pm