Electrophoresis of soft particles with hydrophobic inner core grafted with pH-regulated and highly charged polyelectrolyte layer

Electrophoresis of core-shell composite soft particles possessing hydrophobic inner core grafted with highly charged polyelectrolyte layer (PEL) has been studied analytically. The PEL bears pH-dependent charge properties due to the presence of zwitterionic functional groups. The dielectric permittivity of the PEL and bulk aqueous medium were taken to be different, which resulted in the ion-partitioning effect. Objective of this study was to provide a simple expression for the mobility of such core-shell soft particles under Donnan limit where the thickness of the PEL well exceeds the electric double layer thickness. Going beyond the widely used Debye-Huckel linearization, the nonlinear Poisson-Boltzmann equation coupled with Stokes-Darcy-Brinkman equations was solved to determine the electrophoretic mobility. The derived expression further recovers all the existing results for the electrophoretic mobility under various simplified cases. The graphical presentation of the results illustrated the impact of pertinent parameters on the electrophoretic mobility of such a soft particle.

Automated summary

The study analytically investigated the electrophoresis of core-shell composite soft particles with a hydrophobic inner core grafted with a highly charged polyelectrolyte layer, showing the impact of the pH-dependent charge properties of the polyelectrolyte layer on the electrophoretic mobility. By solving the nonlinear Poisson-Boltzmann equation coupled with Stokes-Darcy-Brinkman equations, a simple expression was derived for the mobility of the soft particles under the Donnan limit, exceeding the electric double layer thickness. The results recovered existing findings and illustrated the influence of key parameters on the electrophoretic mobility.