(363b) Modeling Charge Regulation and Surface Forces Due to Weak Polyelectrolytes

In contrast to strong polyelectrolytes, weak polyelectrolytes exhibit electrostatic charges dependent on the solution pH and local chemical environment. This pH-responsive behavior instills weak polyelectrolytes great versatility in their practical use as a smart system to achieve specific functions such as targeted drug delivery and controlled release but a quantitative description of such behavior remains a challenge. While there has been significant progress in recent decades to describe the titration of weak polyelectrolytes in the bulk and near an interface, these studies describe the degree of protonation in terms of the apparent equilibrium constant that neglects electrostatic correlation effects important for weak polyelectrolytes in a highly inhomogeneous environment. By coupling a molecular thermodynamic model for chemical reactions with the polymer density functional theory, we are able to incorporate correlation effects into the conventional models and describe the interfacial behavior of weak polyelectrolytes in good agreement with experimental data. The theoretical model has been used to study the surfaces forces mediated by a confined weak polyelectrolyte solution to generate insight into the design of bioadhesives such as those mimicking marine animals.