Fast Water Transport in Polyelectrolyte Brush Functionalized Nanochannels*

The need for enhanced transport and enhanced separation in nanochannels is prevalent across disciplines of fluid mechanics, material science, bio-medicine, nanotechnology, etc. In this study, we show that the functionalization of nanochannel with pH-responsive polyelectrolyte (PE) brushes, which we model using newly formulated augmented Strong Stretching theory, can lead to fast electroosmotic (EOS) transport of water. We observe that the presence of PE brushes results in enhanced flux when compared to brush free nanochannel. This is because of the localization of the EDL charge density away from the flow retarding wall. The enhanced flux obtained in brush functionalized nanochannels tends to be comparable to graphene-based state-of-the-art nanostructures which indicate that such a system could be used for fast transport of water. Moreover, we also witness a large gradient in the flow profiles, for certain conditions of the solvent, which suggests that these brush functionalized nanochannels could also be useful in size-based separation of particles.