Regensburg 2007 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 10: INTERNAL SYMPOSIUM Scattering Experiments I
CPP 10.4: Talk
Tuesday, March 27, 2007, 10:30–10:45, H37
Neutron Spectroscopy on nono-confined polymers in comparison with dielectric and thermal results — •Andreas Schoenhals1, Bernhard Frick2, Maria Mayorova3, and Reiner Zorn3 — 1Federal Institute of Materials Research and Testing, Unter den Eichen 87, D-12205 Berlin — 2Institut Laue-Langevin, B.P. 156, F-38042 Grenoble — 3Research Center Jülich, Institute for Solid State Research, D-52425 Jülich
The effect of a nanometre confinement on matter is an interesting problem of soft-matter physics. Neutron scattering (NS) is valuable tool to investigate such systems because of the high penetration depth of neutrons. Incoherent NS was carried out on poly(dimethyl siloxane) and poly(methyl phenyl siloxane) confined to Sol/Gel-glasses (7.5, 5.0, 2.5 nm). To cover a broad dynamical range of the scattering function S(Q,E) time-of-flight and backscattering are combined. For the Boson peak the vibrations at lowest frequencies are depressed by the confinement. The mean square displacement msd was calculated from elastic scanes. Above Tg the characteristic increase of the msd found for the bulk is strongly influenced by the confinement but for both materials in a different manner. The main influence of the confinement on S(Q,t)=FT(S(Q,E)) is an broadening of S(Q,t) with increasing confinement. These results are discussed together with dielectric measurements. This comparison gives strong evidence that (1) the thermodynamic state in a nanometer confinement is different from that of the bulk and that (2) an inherent length scale might exist for the glass transition.