Dresden 2011 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 14: Elastomers and Gels
CPP 14.1: Topical Talk
Dienstag, 15. März 2011, 10:30–11:00, ZEU 114
Network effects in nano-filled polymer systems — •Kay Saalwächter1, Cornelius Franz1, Kerstin Schäler1, Salim Ok2, Martin Steinhart2, Aurelie Papon3, Francois Lequeux3, and Helene Montes3 — 1Institut für Physik - NMR, Martin-Luther-Univ. Halle-Wittenberg, Halle, Germany — 2Institut für Chemie, Universität Osnabrück, Germany — 3Physico-chimie des Polymères et Milieux Dispersés, ESPCI ParisTech, Paris, France
The effect of nanoscopic filler particles on the dynamics of linear and cross-linked chains above Tg is controversial. While often, an increase of the cross-link density in the particle vicinity was claimed, previous work of our group based on the use of low-field multiple-quantum (MQ) NMR has indicated that the homogeneity of the matrix is hardly ever affected by different types of filler [1]. However, in model-filled samples consisting of a dispersion of grafted silica particles, we found a (i) fraction of polymer with slower dynamics and (ii) a fraction with locally increased cross-link density, that both correlate with the silica specific surface. We further discuss related results for linear melt dynamics in nanoscopic model confinement provided by anodic aluminum oxide (AAO) membranes with channels of 20–400 nm diameter [2]. We consistently observe a fraction of chains with less isotropic dynamics on long time scales, behaving network-like. Our results are consistent with a layer thickness of a few nanometers at the non-interacting interface, where the geometric confinement modifies the chain modes.
[1] J. L. Valentín et al., Macromolecules 43, 334 (2010).
[2] S. Ok et al., Macromolecules 43, 4429 (2010).