Regensburg 2007 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 12: Polymer Physics III: Interfaces
CPP 12.7: Talk
Tuesday, March 27, 2007, 11:45–12:00, H40
C60 modified PPO Polymer Membranes: Free Volume by Positron Annihilation Lifetime Spectroscopy — •Jan Kruse1, Klaus Rätzke1, Franz Faupel1, Dana Sterescu2, Dimitrios Stamatialis2, and Matthias Wessling2 — 1Universität Kiel, Lehrstuhl für Materialverbunde, Kaiserstr. 2, 24143 Kiel — 2University of Twente, Membrane Technology Group, P.O. Box 217, 7500 AE, Enschede
PPO (poly(2,6-dimethyl-1,4-phenylene oxide)) is a well known membrane material showing good gas separation properties. Addition of nanoparticles can greatly enhance the performance of composite membranes. We have modified PPO polymer with C60 buckyballs up to a content of 2wt%. Permeability experiments show a strong dependence on whether the C60 is dispersed in the polymer or chemically bonded to the polymer chains. Free volume studies performed by positron annihilation lifetime spectroscopy (PALS) were performed on samples with different C60 concentrations. Spectra of all samples containing C60 exhibit an additional large positronium lifetime, indicating large local free volume elements. The orthopositronium intensity decreases with increasing C60 content, stronger for chemically bonded than for dispersed C60. As the inhibition of positronium formation can be attributed to the C60 molecules, this will be discussed with respect to the homogeneity of distribution.