Regensburg 2013 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 9: Poster: Interfaces and Thin Films (joint session with DECHEMA and VDI)

CPP 9.9: Poster

Montag, 11. März 2013, 17:30–19:30, Poster C

Unusual water uptake in ultrathin polyvinyl acetate films — •Heiko Huth and Christoph Schick — Universität Rostock, Institut für Physik, Wismarsche Str. 43-45, 18051 Rostock, Germany

The water sorption of polyvinyl acetate (PVAc) at different relative humidity for bulk like and ultra-thin films was studied by AC chip calorimetry. For a micrometer sized sample of about 200 ng the plasticizing effect of water vapor is the same as in conventional differential scanning calorimetry (DSC) employing mg samples with closed volume and well defined water content of the mg scale samples is found. With decreasing film thickness the water sorption behavior becomes more complex and an increasing amount of adsorpt excess water is observed. The effect can be discussed as a water layer on top and below the polymeric film dependent on the surface properties of the underlaying sensor surface. For the experiments a new setup to measure heat capacity of thin film samples under controlled humidity was developed. The AC chip calorimeter uses a self-made humidity generator applying mass flow controllers. A quartz crystal microbalance (QCM) allows checking the mass change during water uptake. The technical details of the device and the extensions for humidity control are discussed too.