Abstract
AbstractUsing neutron spin echo spectroscopy, the dynamics of high molecular weight poly(dimethylsiloxane) in the melt (T=473 K) was investigated. In order to decide whether the lateral constraints are uniform or nonuniform with respect to the contour of a test chain, chains were labeled either completely or partially by a corresponding proton‐deuterium exchange. It was found that the central and the terminal chain sequences experience the same amount of lateral confinement, which–in the framework of the reptation or tube model–can be characterized by a tube diameter dt of about 70 Å. Nearly the same dt value is obtained from the plateau modulus of rheological measurements, too. Thus, these experiments show unambiguously that the lateral constraints, responsible for the reptational chain dynamics, are quite homogeneous, even in the case of extremely large tube dimensions.
Published Version
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