Dresden 2026 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 46: Poster II
CPP 46.29: Poster
Thursday, March 12, 2026, 09:30–11:30, P5
PDADMA/PSS Multilayer Buildup in NaBr Solution: Vertical PSS Diffusion and Unusual Growth — •Per-Ole Hilken, Issam Assi, and Christiane A. Helm — Institute of Physics, University of Greifswald, Germany
Polyelectrolyte multilayers form by sequential adsorption of oppositely charged polyelectrolytes. The interfaces between the adsorption layers are fuzzy; in the exponential growth regime of PDADMA/PSS (poly(diallyldimethylammonium)/polystyrene sulfonate) multilayers PSS diffuses vertically through the film. We determine its vertical diffusion coefficient DPSS using a quartz crystal microbalance with dissipation (QCM-D). The scaling laws for DPSS in dependence of the NaBr concentration are similar to those found with NaCl in the deposition solution (Sill et al., Macromolecules 2025), however, the diffusion coefficient is one to two orders of magnitude larger. The dependence on PSS molecular weight MPSS is qualitatively the same as with NaCl in the deposition solution: Polymer diffusion dominates multilayer build-up when MPSS<76 kDa.; at larger MPSS, site diffusion dominates; i.e. diffusion of charged repeat units with their counterions. For polyelectrolyte multilayers in the non-exponential growth regimes it is well known and also found with that an increase in the salt concentration leads to thicker multilayers. This is not the case if the NaBr concentration exceeds ≈0.6 M; additionally, film stability becomes an issue. To understand the unusual behavior, the dissipation during film build-up is quantified. The surface topography is investigated with AFM.
Keywords: Polyelectrolyte diffusion; NaBr concentration; Polyelectrolyte molecular weight; QCM-D; AFM