Future Directions in Physiochemical Modeling of the Thermodynamics of
Polyelectrolyte Coacervates (PECs)
Abstract
We review theories of polyelectrolyte (PE) coacervation, which is the
spontaneous association of oppositely charged units of PEs and phase
separation into a polymer-dense phase in aqueous solution. The simplest
theories can be divided into “physics-based” and “chemistry-based”
approaches. In the former, polyelectrolytes are treated as charged,
long-chain, molecules, defined by charge level, chain length, and chain
flexibility, but otherwise lacking chemical identity, with electrostatic
interactions driving coacervation. The “chemistry-based” approaches
focus on the local interactions between the species for which chemical
identity is critical, and describe coacervation as the result of
competitive local binding interactions of monomers and salts. In this
article, we show how these approaches complement each other by
presenting recent approaches that take both physical and chemical
effects into account. Finally, we suggest future directions towards
producing theories that are made quantitatively predictive by accounting
for both long range electrostatic and local chemically specific
interactions.