Roles of chain conformation and interpenetration in the growth of a polyelectrolyte multilayer

In the present study, we have investigated the growth of a multilayer formed by poly(sodium 4-styrene sulfonate) (PSSS) and poly(diallyldimethylammonium chloride) (PDDA) at different salt concentrations by use of quartz crystal microbalance with dissipation (QCM-D). The frequency change (Deltaf) demonstrates that the exponential growth mode gradually becomes dominant as NaCl concentration (C(NaCl)) increases. On the other hand, the dissipation change (DeltaD) reveals that the deposition is dominated by chain conformation at C(NaCl) < 1.0 M, where the change of the characteristic growth parameter agrees well with the results fit with Debye length. At C(NaCl) > or = 1.0 M, the growth is not determined by chain conformation but by chain interpenetration.