Diffusiophoresis of polyelectrolytes: Effects of temperature, pH, type of ionic species and bulk concentration

Extending previous analyses on rigid particles to non-rigid ones, we model the diffusiophoresis of a pH-regulated polyelectrolyte (PE) in a solution containing multiple ionic species. For the first time, the effects of temperature, pH, type of ionic species and bulk concentration are taken into account, and therefore, the conditions considered are more comprehensive and closer to reality than those of the available results in the literature. Numerical simulation is conducted to examine the diffusiophoretic behaviors of a PE under various conditions, and empirical relationships are developed for the dependence of its mobility on the factors mentioned above. We show that temperature and pH influence appreciably the charged conditions of a PE, the ionic diffusivities, and the fluid viscosity, yielding complicated and interesting behaviors that are informative to device design.