Considering the potential applications of diffusiophoresis conducted in nanodevices, a thorough theoretical analysis is performed for the first time on the diffusiophoresis of a polyelectrolyte (PE) in the presence of two representative types of boundaries: the direction of diffusiophoresis is either normal (type I) or parallel (type II) to a boundary, using two large parallel disks and a cylindrical pore as an example, respectively. It is interesting to observe that due to the effects of double-layer polarization, counterion condensation, polarization of condensed counterions, and diffusion of co-ions across a PE, its diffusiophoretic behavior can be influenced both quantitatively (magnitude of mobility) and qualitatively (direction of diffusiophoresis) by a boundary. In general, type I (II) boundary raises the diffusiophoretic mobility of a PE toward the high (low) salt concentration side. The results gathered provide necessary information for applications in, for example, designing catalytic swimmers and nanopore-based biosensor devices.
The Journal of Physical Chemistry C 117(18), pp.9469–9476