ENHANCED DIFFUSIOOSMOSIS AND THERMOOSMOSIS IN POLYELECTROLYTE-BRUSH-FUNCTIONALIZED NANOCHANNELS

Abstract

One of the holy grails of nanofluidic systems is to ensure significant flow rates without applying a large pressure gradient. This has motivated researchers to study different mechanisms of liquid transport in nanochannels involving physical effects that exploit the large surface-to-volume ratio of such nanochannels. This thesis will focus on two highly efficient non-pressure-driven flow mechanisms in nanochannels functionalized by grafting the inner walls of nanochannels with end-charged polyelectrolyte (PE) brushes. We study two mechanisms to achieve flow augmentation: (i) ionic diffusioosmosis (IDO), triggered by the application of an external concentration gradient, and (ii) ionic thermoosmosis (ITO), triggered by a temperature gradient. We find a non-intuitive scenario where the flow in nanochannels can be significantly augmented by grafting the nanochannels with PE brushes. Given the difficulty in attaining a desirable flow strength in nanochannels, we anticipate that this thesis will serve as an important milestone in the area of nanofluidics.