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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 17: Charged Soft Matter, Polyelectrolytes and Ionic Liquids I
CPP 17.5: Vortrag
Dienstag, 19. März 2024, 10:45–11:00, H 0107
Influence of salt concentration and PSS molecular weight on PSS diffusion constant in PSS/PDADMA multilayers — Annekatrin Sill, •Per-Ole Hilken, and Christiane A. Helm — Institute of Physics, University of Greifswald, 17489 Greifswald, Germany
We determine the diffusion constant DPSS of polystyrene sulfonate (PSS) during the growth of polyelectrolyte multilayer films from poly (diallyldimethylammonium) (PDADMA) and PSS. Quartz crystal microbalance dissipation (QCM-D), AFM, and ellipsometry are used. The molecular weight of PDADMA was kept constant (117 kDa), and the one of PSS (MPSS) was varied between 10 and 64 kDa. At the beginning of film build-up, the film thickness grows exponentially with the number of deposited PDADMA/PSS bilayers. Eventually, a transition to non-exponential growth occurs. From the film thickness at this transition and the adsorption time, the diffusion constant DPSS is determined. Varying the NaCl concentration c (between 0.1 M and 1 M), one finds DPSS=A· e(−β · c) with A as a constant. β decreases linearly on the increase of MPSS. We obtain a power law on varying MPSS: DPSS=B· MPSS−γ, with γ increasing linearly with c and B increasing exponentially. In conclusion, we found equations to predict DPSS for given preparation parameters. In our experiments, the diffusion constant DPSS varied by four orders of magnitude. The dependence of DPSS on adsorption time, PDADMA molecular weight, and post-preparation treatment are discussed.
Keywords: Polyelectrolyte Multilayer; Diffusion