Electrostatic Manipulation of Weak Polyelectrolyte Brushes

End-tethered polyelectrolytes are widely used to modify substrate properties, particularly for lubrication or wetting. External stimuli, such as pH, salt concentration, or an electric field, can induce profound structural responses in weak polyelectrolyte brushes, which can be utilized to further tune substrate properties. While many aspects of weak polyelectrolyte brushes have been explored in the past two decades, their electroresponsiveness in combination with nonelectrostatic effects is not fully understood. Here, we study the charging/discharging of a surface grafted with weak polyelectrolyte brushes. Using a mean field theory, we investigate the combined role of pH, salt concentration, grafting density, and solvent quality (i.e. Flory-Huggins chi parameter) on the brush conformation and the capacitance of the brush.