Density functional theory for charge regulation of inhomogeneous weak polyelectrolytes

In contrast to strong polyelectrolytes, weak polyelectrolytes present electrostatic charges in accordance with the solution pH and the local chemical environment. The pH-responsive behavior is advantageous for use in smart systems to achieve specific functions such as targeted drug delivery and controlled release. Unfortunately, a quantitative description of such charge regulation behavior remains challenging. While there has been significant progress to describe weak polyelectrolytes in the bulk and near an interface, these studies typically neglect electrostatic correlations along the polymer backbone. Furthermore, existing methods cannot capture local electrostatic correlations for inhomogeneous weak polyelectrolytes. In this talk, we present a new theoretical framework for weak polyelectrolytes by coupling a molecular thermodynamic model for chemical reactions with the polymer DFT. By incorporating correlation effects into the conventional titration models, we can describe the behavior of weak polyelectrolytes in agreement with experimental data. This theoretical model is used to study the surface forces mediated by weak polyelectrolytes and generate insight into the design of bioadhesives.