Berlin 2015 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 37: Interfaces and Thin Films III (joint session CPP, DS)
CPP 37.11: Talk
Wednesday, March 18, 2015, 12:15–12:30, C 243
Influence of Barrier Layers on Interdiffusion in Polyelectrolyte Multilayers — •Peter Nestler1, Malte Paßvogel1, Olaf Soltwedel2, Ralf Köhler3, and Chrisitane A. Helm1 — 1Physik, Uni Greifswald, 17487 Greifswald, Germany — 2MPI FKP 70569 Stuttgart, Germany — 3Helmholtz-Zentrum Berlin, 14109 Berlin, Germany
Polyelectrolyte multilayers are made from poly(diallyldimethylam-monium) (PDADMA), poly(styrenesulfonate) (PSS). Using selective PSS deuteration each film consists of a protonated and a deuterated compartment.
During annealing in 1 M NaCl solution the internal interface between these two compartments broadens due to interdiffusion. The PSS diffusion coefficient DPSS inside the multilayer film is quantified via neutron reflectivity. Eventually the annealing leads to a uniform distribution of protonated and deuterated PSS inside the film. If one polycation layer in the film centre is branched poly(ethyleneimine) (PEI), then PEI serves as a diffusion barrier. In this case the barrier is impenetrable for up to 70% of PSS molecules. The diffusion behaviour of the remaining 30% can be described using a position-dependent distribution of DPSS inside the multilayer film. The effective PSS diffusion coefficient is reduced by one to two orders of magnitude.