J. Phys. II France
Volume 1, Numéro 6, June 1991
|Page(s)||659 - 671|
J. Phys. II France 1 (1991) 659-671
Measurements of polymer diffusion over small distances. A check of reptation argumentsG. Reiter1 and U. Steiner2
1 Max Planck Institut für Polymerforschung, P.O.B. 3148, 6500 Mainz, F.R.G.
2 Department of Polymer Research, Weizmann Institute of Science, Rehovot 76100, Israel
(Received 13 December 1990, accepted 4 March 1991)
We performed neutron reflectrometry (NR) and nuclear reaction analysis (NRA) measurements on interdiffusion of protonated and deuterated polystyrene films. Covering several orders of magnitude in time t and resolving interfacial widths w(t) between approximately 2 nm and 60 nm we found two successive time regimes with a crossover corresponding to the reptation time . Below we are able to approximate the interface profile quite well by two superposed error functions described by three parameters, and , p(t). The two contributions are interpreted according to the Rouse and reptation model. While the width of the error function correlated to Rouse type motion stays almost constant, the width of the second contribution increases with time. p(t) represents the percentage of the second contribution at the interface. It increases with time reaching 100 per cent at . An explanation is given in terms of the reptation model. The time behavior of , , p(t) and w(t) is discussed. and are determined independently using three different methods. All results are in qualitative agreement with reptation model.
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