Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 41: Charged Soft Matter, Polyelectrolytes and Ionic Liquids I
CPP 41.4: Vortrag
Freitag, 21. März 2025, 10:30–10:45, H38
Vertical Polyelectrolyte and Site Diffusion of PSS in PSS/PDADMA Multilayers — Annekatrin Sill, •Per-Ole Hilken, and Christiane A. Helm — Institute of Physics, University of Greifswald, Germany
The spontaneous formation of polyelectrolyte multilayers or polyelectrolyte complexes depends on the (inter)diffusion of polyelectrolytes. We investigate the transport of extrinsic sites - charged polyelectrolyte repeat units balanced by counterions - and their relationship to polymer diffusion. We determine the vertical diffusion coefficient DPSS of polystyrene sulfonate (PSS) repeat units in polyelectrolyte multilayer films from poly (diallyldimethylammonium) (PDADMA) and PSS using a quartz crystal microbalance with dissipation (QCM-D) and analyze the observed film growth. Varying the NaCl concentration cNaCl results in DPSS=3.2·10−20 m2/s· eα· cNaCl. As known from the free volume model, the prefactor is constant for each system. For site diffusion, the exponent is also constant (α≈4.9 M−1). For polymer diffusion, however, α increases linearly with MPSS, the molecular weight of PSS. The results for site diffusion quantitatively agree with those of Fares and Schlenoff (JACS (2017) 139; 14656). Polymer diffusion occurs when MPSS < 65 kDa (for MPDADMA=117 kDa). For these low PSS molecular weights, the diffusion coefficient is DPSS=B· MPSS−γ. The dependence of B on cNaCl is a power law, while γ increases linearly with cNaCl.
Keywords: Polyelectrolyte diffusion; NaCl concentration; Polyelectrolyte molecular weight; Free Volume Model