Dresden 2017 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 68: Hydrogels and Microgels II
CPP 68.8: Vortrag
Freitag, 24. März 2017, 12:15–12:30, ZEU 260
Composition of polyanion mixtures influence exponential growth of polyelectrolyte multilayers — •Annkatrin Sill1, Malte Paßvogel1, Antonia Weltmeyer1, Olaf Soltwedel2, Amir Azinfar1, Peter Nestler1, and Chrstiane A. Helm1 — 1Inst. of Physics, Greifswald University, Germany — 2Physics Department, TU Munich, Germany
The exponential growth regime of polyelectrolyte multilayer films made from binary polyanion mixtures is investigated. Films were assembled by the layer-by-layer (LbL) technique using poly(stryrene sulfonate) PSS as polyanion and poly (diallyldimethylammonium) (PDADMA) as polycation and investigated with in-situ ellipsometry and neutron reflectivity. The films grow exponentially if molecular weight Mw(PSS) is below 25 kDa; no exponential film growth occurs if Mw(PSS) is above this threshold. Exponential growth is characterized by diffusion of PSS within the film; in non-exponential growth regimes PSS is immobile. The influence of PSS molecular weight distribution on exponential film growth is investigated using a PSS mixture with molecular weight below and above the threshold value. Multilayer films grow exponentially if the mole fraction of non-diffusing PSS is less than 1 %. Neutron reflectivity shows that the mole fraction of non-diffusing PSS in the film is much larger than in the preparation solution. The effect gets more pronounced with increase of the adsorption time. This finding is attributed to the irreversible adsorption of immobile PSS which replaces mobile PSS which adsorbed first.