The results obtained after assembly of RNA oligonucleotides within PDMAEMA and PMETAI polymer brushes suggest that infiltration takes place within the brush and is not restricted to the surface of the brush, which would be expected to lead to increased density and potentially collapse in the upper layers of the brush rather than deeper within its core. Hence, adsorption of poly(2vinyl benzyl pyridinium) within poly(styrene sulfonate) brushes led to complexation and collapse at the surface of the brush . This behaviour was in sharp contrast to the weak change in brush morphologies observed at moderate small electrolyte (NaCl) concentrations, and the more homogenous collapse of the entire brush nanostructure at higher electrolyte concentrations.