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CPP: Chemische Physik und Polymerphysik

CPP 17: Thin Films and Surfaces II

CPP 17.4: Vortrag

Mittwoch, 29. März 2006, 16:30–16:45, ZEU Lich

Electrical Detection and Characterization of Self-Assembled Polyelectrolyte Multilayers by a Silicon-on-Insulator based Thin Film Resistor — •Petra A. Neff¹, Ali Naji², Regine von Klitzing³, and Andreas R. Bausch¹ — ¹Lehrstuhl für Biophysik - E22, Technische Universität München, Germany — ²Physik Department - T37, Technische Universität München, Germany — ³Institut für Physikalische Chemie, Christian-Albrechts-Universität Kiel, Germany

The build up of polyelectrolyte multilayers (PEMs) was observed by a silicon-on-insulator (SOI) based thin film resistor. Although the structural properties of polyelectrolyte multilayers have been extensively studied, a detailed understanding is still lacking. The layer-by-layer deposition of the polycation poly(allylamine hydrochloride) (PAH) and the polyanion poly(styrene sulfonate) (PSS) results in defined potential shifts, which decrease with the number of layers deposited. We model the response of the device assuming electrostatic screening of polyelectrolyte charges by mobile ions within the PEMs. The screening length κ ⁻¹ inside the PEMs was found to be increased compared to the value corresponding to the bulk solution. Furthermore the partitioning of mobile ions between the bulk phase and the polyelectrolyte film was employed to calculate the dielectric constant of the PEMs and the concentration of mobile charges.