BME Seminar: Formation, Phase Behavior, and Structure of Single and Multiphase Polyelectrolyte Complex Coacerv


3:00 pm-4:00 pm
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Angelika Neitzel, Ph.D., Rhines Rising Star Robert DeHoff Assistant Professor of Materials Science & Engineering, Department of Materials Science & Engineering, University of Florida

Charged polymers are abundant in nature and their electrostatic interactions provide rich physics that pose many open questions. For example, solutions of oppositely charged polymers spontaneously form soft condensed phases known as polyelectrolyte complexes (PECs). These intriguing structures are found in natural systems such as membraneless compartments inside cells and advanced functional and responsive materials (e.g., underwater adhesives used by mussels and sandcastle worms). The ion pairs between polymer chains in PECs act as physical crosslinks, and one of the most powerful methods to alter PEC properties is by tuning their ionic crosslinking density. First, I will discuss our work employing a well-defined, modular polyether platform for the synthesis of homologous polyanions and polycations to quantify single phase polyelectrolyte complexes’ properties and phase behavior across a broad range of polyelectrolyte linear charge densities. This platform is then further utilized to, for the first time, experimentally corroborate decades-old theory describing the internal structure of these complexes using small angle neutron scattering. Finally, we provide insights into the mechanism of multiphase coacervate formation via combination of multiple (>2) charge asymmetric polyelectrolytes containing dye-labeled species for structural visualization using fluorescent microscopy. Our experimental results are compared to available scaling theory and molecular dynamics simulations to rationalize salient features of phase diagrams and structure.


Angelika received a Ph.D. in Materials Science and Engineering at the University of Minnesota under the guidance of Professor Marc Hillmyer. At Minnesota she worked on the ring-opening polymerization of cyclic hemiacetal esters, which yields hydrolytically and thermally degradable polymers. She provided a detailed understanding of the mechanism, kinetics, and thermodynamics of the polymerization of these novel monomers and demonstrated their use as building blocks for the synthesis of polyhemiacetal esters, polyesters, and copolymers. Following her studies at Minnesota, she moved to the University of Chicago to join the research group of Professor Matthew Tirrell. In the Tirrell group, Angelika took on the synthesis and characterization of charged polymers and developed a passion for their physics. Her postdoctoral work spans from the synthesis, structure, and phase behavior of polyelectrolyte complexes to the chain statistics of synthetic polyzwitterions.


Hosted by

Dr. Edward Phelps