Hierarchical self-assembly of polyelectrolytes at interfaces

A diblock copolymer consisting of a fluid hydrophobic block and a PSS (poly(styrene sulfonate)) block self-organizes at the water surface as a monolayer. Two polyelectrolyte brush phases can be distinguished with x-ray reflectivity: at low salt the osmotically swollen brush characterized by stochiometric ion incorporation and constant thickness; at high salt (> 0.1 M) the salted brush, which shrinks both with molecular area and subphase salt, according to the predicted power laws. PSS adsorbed onto a cationic lipid monolayer is studied. Flat and coiled adsorption can be distinguished, depending on salt concentration, monolayer surface charge and degree of polymerisation. Multilayers formed by alternate adsorption of polycations and polyanions show a similar dependence on solution parameters. Investigations with the SFA indicate chain interpenetration in multilayers.