Berlin 2012 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 33: Polymer Dynamics

CPP 33.8: Talk

Thursday, March 29, 2012, 12:00–12:15, C 264

Time-Humidity-Superposition Principle in Conductivity Spectra of Ion-Conducting Polymers — Cornelia Cramer¹, Souvik De^1,2, and •Monika Schönhoff¹ — ¹Institute of Physical Chemistry, University of Muenster, Corrensstraße 28/30, 48149 Münster, Germany — ²Graduate School of Chemistry, University of Muenster, Corrensstraße 28/30, 48149 Münster, Germany

We analyze the scaling properties of the ac conductivity spectra of ion-conducting polyelectrolyte complexes (PEC) of different compositions. PEC are composed of cationic poly(diallyldimethyl ammonium chloride)(PDADMAC) and anionic poly(sodium 4-styrene sulfonate) (NaPSS) and pressed into dry, solid pellets. Frequency-dependent spectra were taken at ambient temperature but at different relative humidities.

Enhanced humidity increases the long range transport (dc conductivity) as well as the local motions, characterised by the onset of conductivity dispersion. Even more, the complete spectral shape of spectra taken at different humidity can be superimposed to a mastercurve. Thus, for the first time, we report on a scaling principle for conductivity spectra termed 'time-humidity-superposition principle' in analogy with the well-known time-temperature-superposition principle. This model-free scaling holds for different materials over several decades in frequency. It implies that the hydration is activating ion motion over short and long distances in a similar, general way, a concept so far only established for thermal energy.

(1) Cramer, De, Schönhoff Phys. Rev. Lett. 107, 028301 (2011)