Electrokinetics in pH-responsive polyelectrolyte-brush-grafted nanochannels: Effect of the appropriate Strong Stretching Theory representation of the polyelectrolytes*

Functionalization nanochannels with polyelectrolyte (PE) brushes, contrary to the classical notion, has recently been established to augment electroosmotic (EOS) transport in nanochannels under special conditions where charges of the brushes are localized at the non-grafted ends of the PEs. Here we shall re-visit these calculations as well consider the more readily encountered situations where the entire PE molecule is charged in presence of the most rigorous framework where the PE brushes are modeled using the Strong Stretching Theory (SST) that accounts for the excluded volume (EV) effects and the effect of considering a generalized mass action law. These considerations would significantly affect the monomer distribution (which in turn would affect the drag force imparted by PE brushes) and the resulting EDL (electric double layer) electrostatics (which in turn would affect the EOS body force). This model would be the first rigorous theory for the electrohydrodynamics in the PE-brush-functionalized nanochannels accounting for the appropriate coupled thermodynamic representation of the PE brush configurations and the EDL electrostatics.