Measurements of polymer diffusion over small distances. A check of reptation argumentsReport as inadecuate




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Abstract : 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 wt between approximately 2 nm and 60 nm we found two successive time regimes with a crossover corresponding to the reptation time τd. Below τd we are able to approximate the interface profile quite well by two superposed error functions described by three parameters, σct and σtt, pt. The two contributions are interpreted according to the Rouse and reptation model. While the width σc of the error function correlated to Rouse type motion stays almost constant, the width σt of the second contribution increases with time. pt represents the percentage of the second contribution at the interface. It increases with time reaching 100 per cent at τd. An explanation is given in terms of the reptation model. The time behavior of σct, σtt, pt and wt is discussed. τd and wτd are determined independently using three different methods. All results are in qualitative agreement with reptation model.





Author: G. Reiter U. Steiner

Source: https://hal.archives-ouvertes.fr/



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