Dresden 2014 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 51: Charged Soft Matter II
CPP 51.3: Talk
Thursday, April 3, 2014, 15:30–15:45, ZEU 118
Influence of Polycation Molecular Weight on Interdiffusion in Polyelectrolyte Mulitlayers — •Peter Nestler1, Malte Paßvogel1, Olaf Soltwedel2, Ralf Köhler3, and Christiane A. Helm1 — 1Inst. f. Physik, Uni Greifswald, 17487 Greifswald, Germany — 2MPI für Festkörperforschung, 70569 Stuttgart, Germany — 3Inst. of Soft Matter and Functional Materials, HZB, Berlin, Germany
For the past twenty years, the Layer-by-Layer technique (LbL) has made it possible to modify surfaces by covering them with thin films. A wide variety of potential applications for polyelectrolyte multilayers (PEM) are demonstrated, for example chemical reactors, antireflective coatings or microcontainers. For all these applications, it is important to control thickness, structure and internal diffusion of the film under different external conditions.
PEMs are made from poly(diallyldimethylammonium) (PDADMA), poly(styrenesulfonate) (PSS), and deuterated PSS-d. Each film consists of a protonated and a deuterated compartment. The films are annealed in 1 M NaCl and investigated with neutron reflectivity. During annealing the internal interface between both departments broadens due to interdiffusion.
The PSS interdiffusion constant depends non-monotonically on the PDADMA molecular weight, a maximum is observed at 45 kDa, then it decreases by a factor of 3000. The results suggest that PSS and PDADMA move as a complex. Variation of the position of the internal interface as well as the nature of the top layer give insights into the charge distribution within the multilayer films.