(413d) Tuning Complex Coacervation Using Sequence-Defined Polyelectrolytes: A Molecular Understanding

Oppositely-charged polyelectrolytes can undergo an associative phase separation to form a polymer-dense 'complex coacervate' phase. This electrostatically-driven phase separation is used in a broad array of applications, ranging from food science to self-assembled materials. A fundamental understanding of these materials is necessary for materials design, however a comprehensive physical picture of complex coacervation is still emerging. Our work has demonstrated that the phase behavior of complex coacervate-forming systems is very sensitive to molecular detail, such as short-range interactions and charge spacing. We use computer simulation to demonstrate that this connection between monomer-level structure and coacervation extends to charge sequence. This is reinforced by experimental data, which links the 'blockiness' of a coacervate sequence to phase behavior in qualitative and near-quantitative agreement with simulations. We demonstrate that the physical origin of this sequence-dependent behavior is due to non-uniform counterion condensation effects that can be captured in simple theoretical models. This provides a route to realizing materials that utilize sequence-defined polymers to dictate bulk material properties.