Modulation of electroosmotic flow by electric field-responsive polyelectrolyte brushes: a molecular dynamics study

Molecular dynamics simulations were done to study the electroosmotic flow (EOF) transport in a nanochannel grafted with polyelectrolytes under the control of an electric field normal to the channel wall. This study first addresses some problems on the interplay between complex EOF and non-equilibrium conformational behavior of polyelectrolyte brushes at a molecular level. We demonstrated that changing the normal electric field has a significant impact on the conformational transition of polyelectrolytes and ion distributions, further leading to some new flow phenomena. The coupling mechanisms of polyelectrolyte chain dynamics and electrohydrodynamics were discussed. A remarkable result obtained is that fluid flux depends nonmonotonically on the normal electric field. Our work provides fundamental understanding of the EOF modulation using polyelectrolyte brushes and guidance for the design of smart nanofluidic channels.