Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 8: Poster: Nanoparticles and Composite Materials

CPP 8.25: Poster

Montag, 26. März 2012, 17:30–20:00, Poster A

Humidity-tunable electronic conductivity of polyelectrolyte multilayers doped with Au-nanoparticles — Annika Ziegemeier, Cornelia Cramer, and •Monika Schönhoff — Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstr. 28/30, 48149 Münster, Germany

The dc conductivity of polyelectrolyte multilayers doped with gold nanoparticles (Au-nP) was investigated as a function of relative humidity. For this purpose, multilayers composed of poly(ethyleneimine) (PEI) or poly(allylamine hydrochloride) (PAH) and Au-nP (diameter about 20 nm) were built up using the layer-by-layer self assembly technique. Different polyelectrolytes and varying salt concentrations lead to differences in the total layer thickness and the Au-nP coverage, i.e. different interparticle distances. The dc conductivity of the doped systems is six orders of magnitude higher than that of ions in undoped multilayers, thus an electronic conductivity can be concluded. Electrons are transported via connected pathways of Au-nP, as concluded from the conductivity scaling inversly with the expected particle distance in different systems. With increasing relative humidity (RH) the dc conductivity decreases and reversibly increases again when RH is decreased. It is concluded that the swelling of the polyelectrolyte chains between adjacent particles leads to a loss of connectivity of the electronic pathways between single particles, driving the system closer to the percolation threshold, and resulting in a decrease of conductivity. In conclusion, the conductivity of polyelectrolyte multilayers doped with Au-nP can be reversibly tuned by varying the relative humidity.