The structure of polyelectrolyte multilayers built up by alternate adsorption of polyanions and polycations was investigated by neutron reflectivity at the solid/liquid interface.
The experiment provides detailed information on the density gradient of polyelectrolyte chains across the films and shows the influence of the water content of the film on the internal structure. The polyelectrolyte density is determined by the adsorption conditions (e.g. amount of NaCl) and cannot be changed by addition of salt after adsorption. After drying, the film thickness is reduced by 30%.
(Courtesy of R. v. Klitzing)