(537f) [Invited Talk] Thermodynamics and Molecular Engineering of Complex Coacervates

Liquid-liquid phase separation is recognized as a key mechanism for organizing biochemical reactions within distinct intracellular compartments, and potentially hierarchical compartmentalization, where multiple immiscible condensates are present. Complex coacervation is a liquid-liquid phase separation phenomenon with many parallels to biomolecular condensates that results from the complexation of oppositely charged macro-ions. The driving force for coacervation comes from the electrostatic attraction between oppositely charged polyelectrolytes, coupled with entropic gains associated with the release of bound counterions and the restructuring of water. We have explored a range of different polymer systems to develop a molecular-level understanding of polyelectrolyte complexation, including well-controlled model systems such as sequence-controlled polypeptides to understand how molecular level features, as well as the identity of both small molecule salt ions and the chemistry of our polyelectrolytes affects the driving force and subsequent phase behavior of coacervate forming systems. We further leverage our thermodynamic characterization of these systems to correlate differences in the energetics of binding between different polyelectrolyte species with the propensity to form multi-phase, hierarchical coacervates. Ultimately, our goal is to establish a thermodynamically-informed, molecular-level set of design rules to facilitate the tailored creation of materials based on complex coacervation that can both illuminate self-assembly phenomena found in nature, and find utility across a wide range of real-world applications.