Dresden 2009 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 39: POSTERS Colloids and Liquids
CPP 39.15: Poster
Donnerstag, 26. März 2009, 17:00–19:30, P3
Soft X-ray induced modifications & quantitative Analysis of PVA-based Microballoons (MBs) — •Birgit Graf-Zeiler1, George Tzvetkov1, Paulo Fernandes2, Andreas Fery3, and Rainer Fink1 — 1Universität Erlangen, Physikal. Chemie II, Erlangen — 2MPI for Colloids & Interfaces, Potsdam — 3Universität Bayreuth, Physikal. Chemie II, Bayreuth
We describe the characterization of poly(vinyl alcohol) (PVA)based gas-filled MBs in water using scanning transmission X-ray microspectroscopy (STXM)[1]. The PolLux-STXM (SLS) combines NEXAFS with high-resolution microscopy, thus providing high chemical sensitivity and spatial resolutions <40 nm. The different absorption contrast below and above the O K-edge can provide unique information on the interior of the MBs. Soft x-ray illumination leads to the shrinking of the MBs. Nearly no change in the shell thickness can be verified, but the degradation of the PVA network and formation of carbonyl- and carboxyl-containing species could be detected. Based on existing theoretical models the radial transmittance profiles were evaluated[2]. These models are based on an ideal system of perfectly spherical MBs where the density gradient of the stabilizing shell and the finite beam width of the focused X-ray beam are taken into account. We have recently extended the existing models in order to explore the chemical composition of the stabilizing shell in greater detail with particular emphasis to quantify the gradient of water within the shell. Funded by the BMBF, project 05KS7WE1. [1]Tzvetkov et al., Soft Matter, 2008, 4, 510. [2]Fernandes et al., Langmuir, 2008, 24, 13677.