J. Phys. IV France 10 (2000) Pr7-233-Pr7-237
Is the chain dynamics in thin polymer films isotropic ?S. Rivillon1, P. Auroy2 and B. Deloche1
1 Laboratoire de Physique des Solides, UMR 8502 du CNRS, Université Paris-Sud, 91405 Orsay cedex, France
2 Institut Curie, Section de Recherches, UMR l68 du CNRS, 11 rue Pierre et Marie Curie, 75005 Paris, France
The dynamics of molten polymer chains (polydimethylsiloxane) confined between air and a solid, wettable and non-adsorbing surface, is investigated using NMR. The basic approach used here consists in studying how nuclear interactions are time-averaged by rapid molecular motions. Chain segments in such molten films undergo uniaxial reorientations around the normal to the surfaces. The influence of the film thickness ( 50 ≤ h ≤ 3500 Å ) proves this dynamic uniaxiality involves rapid segment diffusion between both surfaces which impose a high degree of planar orientation. Thus the segmental ordering is observed over a thickness range which depends on the degree of chain entanglements.
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