Characterization of partially sulfonated polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene thin films...

The spectroelectrochemical sensor uses thin, solid polyelectrolyte films as an essential element in its operation. In this work we explored the potential of partially sulfonated polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SSEBS) thin polymer films for chemical sensing. Spectroscopic ellipsometry was used to measure optical and surface properties of the air-dried and hydrated material. SSEBS incorporates a relatively small amount of water (overall change of 25%) mainly determined by the complex dynamics of the film. The decrease in the refractive index after complete hydration of the film can be predicted based on the magnitude of swelling using effective medium approximation models. Adhesion of the material on various surfaces (glass, indium tin oxide, gold) was evaluated with the tape peel-off method. The ability of the SSEBS material to preconcentrate cations was evaluated by cyclic voltammetry, absorbance, and luminescence measurements using model analytes (Ru(bpy)(3)(2+), phenosafranine, and rhodamine 6G). The detection limits of the sensor for Ru(bpy)(3)(2+) under unoptimized conditions can be significantly improved if luminescence is used as the detection modality (DL = 5 x 10(-10) M) instead of absorbance (DL = 5 x 10(-7) M). Overall, the results demonstrate the effectiveness of the SSEBS material for spectroelectrochemical sensing.