Hydrophilic and Apolar Hydration in Densely Grafted Cationic Brushes and Counterions with Large Mobilities.

We employ an all-atom molecular dynamics (MD) simulation framework to unravel water microstructure and ion properties for cationic [poly(2-(methacryloyloxy)ethyl) trimethylammonium chloride] (PMETAC) brushes with chloride ions as counterions. First, we identify locally separate water domains (or first hydration shells) each around {N(CH)} and the C═O functional groups of the PMETAC chain and one around the Cl ion. These first hydration shells around the respective moieties overlap, and the extent of the overlap depends on the nature of the species triggering it.