The effect of microscopic spatial restrictions on the segmental diffusion of dense polymer systems: Their observation and analysis by neutron spin echo spectroscopy
The high-resolution neutron spin echo (NSE) spectroscopy provides the unique chance to study the segmental diffusion of polymeric systems simultaneously in space and time. In particular, information on the internal relaxation of single molecules or parts of single molecules may be obtained from dense systems, if the method of labelling by hydrogen deuterium exchange is used.
Whereas in general, a single Rouse dynamics is observed at short times, deviations towards a time-independent behaviour occur on larger time scales, if spatial constraints become effective. Provided that these deviations exhibit a systematic dependence on the magnitude of the scattering vector Q, they allow to derive a well-defined spatial regime where unrestricted Rouse dynamics is dominant.
In this contribution the effect of three completely different kinds of spatial constraints on the segmental diffusion occurring in high molecular weight homopolymer melts, in the compatible regime of low molecular weight polymer blends and in polymer networks, respectively, will be made evident and analysed.
Key wordsSegmental diffusion neutron spin echo spectroscopy melts polymer mixtures networks
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