(59g) Tunable Coacervation from Stoichiometrically Asymmetric Homologous Polyions

The stability of coacervation is sensitive to the monomeric details of the complexed polyions. Recent work has elucidated the effects of chain length, backbone stiffness, charge patterning, and local polarity on coacervation, though have mostly been restricted to stoichiometrically symmetric samples. Systems with imbalanced polycation and polyanion concentrations have been probed, but the picture is incomplete. Our attempts at the characterization and modeling of a homologous pairs of polyions are presented, and expanded upon by progressively tuning polyion composition asymmetry. Both experimental and theoretical coacervation phase diagrams are presented, revealing a surprising curve-in behavior at low ionic strength unseen in stoichiometrically symmetric samples. The underlying driving force is rationalized by considering the balance between the translational entropy of small ions and polyions and the demand for overall charge neutrality, and the partitioning of distinct chemical species is discussed.