文档介绍：
Neutron Spin Echo Investigations on the
Segmental Dynamics of Polymers in Melts,
Networks and Solutions
B. Ewen, D. Richter
MPI fu¨ r Polymerforschung, Postfach 3148, 55021 Mainz, Germany
Institut fu¨ r Festko¨ rperforschung, Forschungszentrum Ju¨ lich,
Postfach 1913, 52425 Ju¨ lich, Germany
Neutron spin echo (NSE) spectroscopy, an advanced high-resolution quasi-elastic neutron scatter-
ing technique, provides the unique opportunity to investigate long-range relaxation processes of
macromolecules simultaneously in space and time on nano-scales. In particular, information on the
single-chain behavior is not restricted to dilute solutions, but may also be obtained from concen-
trated solutions and melts, if labelling by proton deuterium exchange is used. Thus, this method
facilitates a direct microscopic study of molecular models developed to explain the macroscopic
dynamic properties of polymers, . transport and viscoelastic phenomena.
This article gives a short outline of the method and reviews the relevant experimental results
obtained from polymer melts works and from dilute and semi-dilute solutions of chain
molecules with different architectures since the first essful NSE work on polymers was published
in 1978. The experimental observations pared with the predictions of the related microscopic
models and other theoretical approaches, which are briefly introduced and adapted accordingly.
1 Introduction .................................. 3
2 Quasi-Elastic Neutron Scattering ...................... 4
Principles of the Method . . . . . . . . . . . . . . . . . . . . . . . . 4
Neutron Spin Echo Technique . . . . . . . . . . . . . . . . . . . . . 6
Neutron Spin Manipulations with ic Fields . . . . . 7
The Spin Echo Spectrometer . . . . . . . . . . . . . . . . . . 8
3 Polymer Motion in Dense Environments ................. 11
Rouse Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
.