By use of in situ atomic force microscopy, polyelectrolyte multilayers were shown to swell on exposure
to solutions containing salt. The quasilinear swelling response, used to estimate swelling coefficients and
equilibria, exhibits orders of magnitude of difference, depending on the pair of polyelectrolytes constituting
the multilayer. The surface roughness of as-made multilayers was observed to decrease significantly upon
annealing in salt solutions.