Neutron reflectivity study of hydration state of charged polymer brushes

Polymer brush is a ubiquitous model for polymer interfaces. Charged polymer brushes exhibit unique interfacial characteristics in contrast to the non-charged counterpart due to electrostatic interactions while showing excellent dispersion stability, lubrication, and anti-fouling properties in aqueous environments. The hydrated-swollen state of charged polymer brushes is essential to address the molecular mechanism. Neutron reflectivity is a non-destructive quantitative method to figure out the hydrated-swollen state of polymer brushes as the vertical molecular chain density profile. In this review, we describe our neutron reflectivity studies on the hydrated-swollen state of polyelectrolyte brushes, zwitterionic polymer brushes, and polyelectrolyte brush/polyelectrolyte complex thin films, which is modulated by their molecular structure and interactions with electrolytes. (author)